LUBRICANT ADDITIVES AND METHODS OF USE THEREOF

RELATED APPLICATION

This application claims the benefit of priority of LT.S. Provisional Application Serial No. 62/609,079 filed on December 21, 2017, which application is incorporated by reference herein.

BACKGROUND OF THE INVENTION

Lubricants undergo decomposition via oxidation under conditions of high temperature and shear. The addition of antioxidants to lubricant formulations can mitigate oxidative degradation, significantly enhancing the performance and overall lifetime of the lubricant. While numerous oil-soluble antioxidants, particularly hindered phenolic compounds and

diphenylamine derivatives, have been employed to protect lubricant formulations against oxidative degradation, these additives are often toxic. Due to their limited oil-solubility, other hydrophilic phenolic compounds have remained largely unexplored as lubricant antioxidants (e.g., kojic acid, ferulic acid, salicylic acid, curcuminoids and catechols).

Currently, there is a need for new oil-soluble lubricant additives that are capable of reducing oxidative degradation and that have reduced toxicity.

SUMMARY OF THE INVENTION

Accordingly, described herein are oil-soluble lubricant additives, which are based on biodegradable chemicals.

Certain embodiments of the invention provide a compound of formula (I):

wherein,

Ri and R ₂ are each independently (C ₅ -C ₃ o)alkyl or (C5-C ₃ o)alkenyl; and

L is a linking group that comprises one or more antioxidant groups.

Certain embodiments of the invention also provide a lubricating oil composition comprising a lubricating oil base stock and a compound of formula (I) as described herein.

Certain embodiments of the invention provide a lubricating oil composition prepared by combining a lubricating oil base stock and a compound of formula (I) as described herein. Certain embodiments of the invention also provide a method for reducing the oxidative degradation of a lubricating oil composition, comprising adding to the lubricating oil

composition a compound of formula (I) as described herein.

Certain embodiments of the invention provide a method for extending the lifetime of a lubricating oil composition in a system, comprising adding to the lubricating oil composition a compound of formula (I) as described herein.

The invention also provides processes and intermediates disclosed herein that are useful for preparing compounds of formula (I), or salts thereof. For example, intermediates include compounds of formula (I), wherein Ri and R ₂ are each independently H or a protecting group, such as a (Ci-C ₄ )alkyl.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1. Method for coupling oleophilic chains to antioxidant-containing diacids to yield oil-soluble antioxidants. The variable“R” may be“Ri” or“R ₂ ” as defined herein; and the variable“Y” represents certain embodiments of“L” as defined herein (see, e.g., formula (la)).

Figure 2. Thermogravimetric analysis curves of FA + adipoyl diacid (3), FA + ox diacid (6) and SA + adipoyl (9) in air. The heating speed was 10 °C min ¹ .

Figure 3. Thermogravimetric analysis curves of C8C10 (4) and C10C12 (5) in air and Ar atmosphere. The heating speed was 10 °C min ¹ .

Figure 4. Photo of material in different solvents. Solubility of the diacids and corresponding diesters in hexane (up) and in PAO (down). From left: ferulic adipic diacid (3); ferulic oxalic diacid (6); salicylic adipic diacid (9); C8C10 ferulic adipic diester (4); C8C10 ferulic oxalic diester (14); and C8C10 salicylic adipic diester (19). The concentration is 1 mg/mL.

DETAILED DESCRIPTION

Described herein is the development of alternative compounds that may be used as lubricant additives to enhance the performance of lubricating oils and that have reduced toxicity. Specifically, as described in the Examples, a series of diacid intermediates shown to withstand high temperatures (e.g., over 230 °C) were developed using bifunctional water-soluble antioxidants. The oil-solubility of these compounds was then enhanced through the conjugation of long-chain alcohols (or fatty acids) via standard carbodiimide coupling. Because these materials are based on biodegradable chemicals, they are less toxic as compared to conventional additives, such as hindered phenolic compounds and diphenylamine derivatives.

CERTAIN EMBODIMENTS OF COMPOUNDS OF FORMULA (I)

Accordingly, certain embodiments of the invention provide a compound of formula (I):

wherein,

Ri and R ₂ are each independently (C5-C ₃ o)alkyl or (C5-C ₃ o)alkenyl; and

L is a linking group that comprises one or more antioxidant groups.

Certain other embodiments of the invention provide a compound of formula (I):

wherein,

Ri and R ₂ are each independently (Cio-C ₂₅ )alkyl or (Cio-C ₂ s)alkenyl; and L is a linking group that comprises one or more antioxidant groups.

As used herein, the term“antioxidant group” refers to functional groups which inhibit, delay or prevent oxidation. Thus, in certain embodiments, the antioxidant group is an antioxidant phenol group, an antioxidant phenol ether group or a pyranone (e.g., 4-H-pyran-4- one). In certain embodiments, the antioxidant group is derivable from catechol, kojic acid, salicylic acid, ferulic acid or curcuminoid. In certain embodiments, the antioxidant group is derivable from salicylic acid. In certain embodiments, the antioxidant group is derivable from ferulic acid. In certain embodiments, the antioxidant group is derivable from kojic acid.

In certain embodiments, the compound of formula (I) is a compound of formula (la):

wherein, Ri and R ₂ are each independently (C5-C ₃ o)alkyl or (C5-C ₃ o)alkenyl; and L is a linking group that comprises one or more antioxidant groups.

In certain embodiments, the compound of formula (I) is a compound of formula (la’):

wherein,

Ri and R ₂ are each independently (Cio-C ₂₅ )alkyl or (Cio-C ₂ s)alkenyl; and L is a linking group that comprises one or more antioxidant groups.

In certain embodiment the compound of formula (I) is a compound of formula (lb):

wherein,

Ri and R ₂ are each independently (C ₅ -C3o)alkyl or (C ₅ -C3o)alkenyl; and x is 1, 2, 3, 4, 5, 6, 7, 6, 9, or 10.

In certain embodiment the compound of formula (I) is a compound of formula (lb’):

wherein,

Ri and R ₂ are each independently (Cio-C ₂₅ )alkyl or (Cio-C ₂ s)alkenyl; and x is 1, 2, 3, 4, 5, 6, 7, 6, 9, or 10.

In certain embodiments, the compound of formula (I) is a compound of formula (Ic):

wherein,

Ri and R ₂ are each independently (C5-C ₃ o)alkyl or (C5-C ₃ o)alkenyl;

Rio and Rn are each independently H or (Ci-C ₆ )alkoxy; and

x is 1, 2, 3, 4, 5, 6, 7, 6, 9, or 10.

In certain embodiments, L is an oligomeric linking group that comprises one or more antioxidant groups. In certain embodiments, L is an oligomeric linking group that comprises one or more antioxidant groups in the oligomer backbone.

In certain embodiments, L is a polymeric linking group that comprises one or more antioxidant groups. In certain embodiments, L is a polymeric linking group that comprises one or more antioxidant groups in the polymer backbone.

In certain embodiments, the linking group has a molecular weight of from about 20 daltons to about 8,000 daltons. In certain embodiments, the linking group has a molecular weight of from about 200 daltons to about 8,000 daltons. In certain embodiments, the linking group has a molecular weight of from about 20 daltons to about 5,000 daltons. In certain embodiments, the linking group has a molecular weight of from about 20 daltons to about 1,000 daltons. In certain embodiments, the linking group has a molecular weight of from about 200 daltons to about 5000 daltons. In certain embodiments, the linking group has a molecular weight of from about 200 daltons to about 1000 daltons. In certain embodiments, the linking group has a molecular weight of from about 500 daltons to about 2000 daltons.

In certain embodiments, the linking group is a divalent, branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 5 to 300 carbon atoms, wherein one or more (e.g. 1, 2, 3, or 4) of the carbon atoms is optionally independently replaced by a divalent phenyl or (-0-), and wherein the chain is optionally substituted on carbon with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci-C ₆ )alkoxy, (C3-C ₆ )cycloalkyl, (Ci-C ₆ )alkanoyl, (Ci- C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, (Ci-C ₆ )alkylthio, azido, cyano, nitro, halo, hydroxy, oxo (=0), carboxy, aryl, aryloxy, heteroaryl, and heteroaryl oxy, and wherein the divalent phenyl is optionally substituted with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci- C ₆ )alkoxy, (Ci-C ₆ )alkanoyl, (Ci-C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, halo, hydroxy, and carboxy.

In certain embodiments, the linking group is a divalent, branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 5 to 200 carbon atoms, wherein one or more (e.g. 1, 2, 3, or 4) of the carbon atoms is optionally independently replaced by a divalent phenyl or (-0-), and wherein the chain is optionally substituted on carbon with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci-C ₆ )alkoxy, (C3-C ₆ )cycloalkyl, (Ci-C ₆ )alkanoyl, (Ci- C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, (Ci-C ₆ )alkylthio, azido, cyano, nitro, halo, hydroxy, oxo (=0), carboxy, aryl, aryloxy, heteroaryl, and heteroaryl oxy, and wherein the divalent phenyl is optionally substituted with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci- C ₆ )alkoxy, (Ci-C ₆ )alkanoyl, (Ci-C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, halo, hydroxy, and carboxy.

In certain embodiments, the linking group is a divalent, branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 5 to 100 carbon atoms, wherein one or more (e.g. 1, 2, 3, or 4) of the carbon atoms is optionally independently replaced by a divalent phenyl or (-0-), and wherein the chain is optionally substituted on carbon with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci-C ₆ )alkoxy, (C3-C ₆ )cycloalkyl, (Ci-C ₆ )alkanoyl, (Ci- C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, (Ci-C ₆ )alkylthio, azido, cyano, nitro, halo, hydroxy, oxo (=0), carboxy, aryl, aryloxy, heteroaryl, and heteroaryl oxy, and wherein the divalent phenyl is optionally substituted with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci- C ₆ )alkoxy, (Ci-C ₆ )alkanoyl, (Ci-C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, halo, hydroxy, and carboxy.

In certain embodiments, the linking group is a divalent, branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 5 to 30 carbon atoms, wherein one or more (e.g. 1, 2, 3, or 4) of the carbon atoms is optionally independently replaced by a divalent phenyl or (-0-), and wherein the chain is optionally substituted on carbon with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci-C ₆ )alkoxy, (C3-C ₆ )cycloalkyl, (Ci-C ₆ )alkanoyl, (Ci- C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, (Ci-C ₆ )alkylthio, azido, cyano, nitro, halo, hydroxy, oxo (=0), carboxy, aryl, aryloxy, heteroaryl, and heteroaryloxy, and wherein the divalent phenyl is optionally substituted with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci- C ₆ )alkoxy, (Ci-C ₆ )alkanoyl, (Ci-C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, halo, hydroxy, and carboxy.

In certain embodiments, the linking group is a divalent, branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 10 to 30 carbon atoms, wherein one or more (e.g. 1, 2, 3, or 4) of the carbon atoms is optionally independently replaced by a divalent phenyl or (-0-), and wherein the chain is optionally substituted on carbon with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci-C ₆ )alkoxy, (C3-C ₆ )cycloalkyl, (Ci-C ₆ )alkanoyl, (Ci- C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, (Ci-C ₆ )alkylthio, azido, cyano, nitro, halo, hydroxy, oxo (=0), carboxy, aryl, aryloxy, heteroaryl, and heteroaryloxy, and wherein the divalent phenyl is optionally substituted with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci- C ₆ )alkoxy, (Ci-C ₆ )alkanoyl, (Ci-C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, halo, hydroxy, and carboxy.

In certain embodiments, the linking group is a divalent, branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 5 to 20 carbon atoms, wherein one or more (e.g. 1, 2, 3, or 4) of the carbon atoms is optionally independently replaced by a divalent phenyl or (-0-), and wherein the chain is optionally substituted on carbon with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci-C ₆ )alkoxy, (C3-C ₆ )cycloalkyl, (Ci-C ₆ )alkanoyl, (Ci- C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, (Ci-C ₆ )alkylthio, azido, cyano, nitro, halo, hydroxy, oxo (=0), carboxy, aryl, aryloxy, heteroaryl, and heteroaryloxy, and wherein the divalent phenyl is optionally substituted with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci- C ₆ )alkoxy, (Ci-C ₆ )alkanoyl, (Ci-C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, halo, hydroxy, and carboxy.

In certain embodiments, the linking group is a divalent, branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 10 to 20 carbon atoms, wherein one or more (e.g. 1, 2, 3, or 4) of the carbon atoms is optionally independently replaced by a divalent phenyl or (-0-), and wherein the chain is optionally substituted on carbon with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci-C ₆ )alkoxy, (C3-C ₆ )cycloalkyl, (Ci-C ₆ )alkanoyl, (Ci- C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, (Ci-C ₆ )alkylthio, azido, cyano, nitro, halo, hydroxy, oxo (=0), carboxy, aryl, aryloxy, heteroaryl, and heteroaryloxy, and wherein the divalent phenyl is optionally substituted with one or more (e.g. 1, 2, 3, or 4) substituents selected from (Ci- C ₆ )alkoxy, (Ci-C ₆ )alkanoyl, (Ci-C ₆ )alkanoyloxy, (Ci-C ₆ )alkoxycarbonyl, halo, hydroxy, and carboxy.

In certain embodiments, L comprises one or more antioxidant phenol groups or antioxidant phenol ether groups.

In certain embodiments, L comprises one or more groups derivable from catechol, salicylic acid, ferulic acid or curcuminoid.

In certain embodiments, L comprises one or more groups derivable from ferulic acid.

In certain embodiments, L comprises one or more groups derivable from salicylic acid.

In certain embodiments, L comprises one or more groups derivable from kojic acid. In certain embodiments, L comprises one or more pyranone groups (e.g., 4-H-pyran-4- one).

In certain embodiments, L is:

In certain embodiments, Ri is (C ₅ -C ₃ o)alkyl. In certain embodiments, Ri is (C ₈ -

C ₂₅ )alkyl. In certain embodiments, Ri is (Cio-C ₂₅ )alkyl. In certain embodiments, Ri is (C ₁₅ - C ₂₅ )alkyl. In certain embodiments, Ri is (Ci ₅ -C ₂ o)alkyl. In certain embodiments, Ri is (C ₅ - Ci ₅ )alkyl.

In certain embodiments, Ri is (C ₅ -C ₃ o)alkenyl. In certain embodiments, Ri is (C ₈ - C ₂₅ )alkenyl. In certain embodiments, Ri is (Cio-C ₂₅ )alkenyl. In certain embodiments, Ri is (Ci ₅ -C ₂₅ )alkenyl. In certain embodiments, Ri is (Ci ₅ -C ₂ o)alkenyl. In certain embodiments, Ri is (C ₅ -Ci ₅ )alkenyl.

In certain embodiments, Ri is (C ₅ -C ₃₀ ) mono-, di-, or tri-enyl. In certain embodiments, Ri is (C ₈ -C ₂₅ ) mono-, di-, or tri-enyl. In certain embodiments, Ri is (C ₁₀ -C ₂₅ ) mono-, di-, or tri- enyl. In certain embodiments, Ri is (C ₁₅ -C ₂₅ ) mono-, di-, or tri-enyl. In certain embodiments, Ri is (C ₁₅ -C ₂₀ ) mono-, di-, or tri-enyl. In certain embodiments, Ri is (C ₅ -C ₁₅ ) mono-, di-, or tri- enyl.

In certain embodiments, Ri is:

In certain embodiments, Ri is:

In certain embodiments, R ₂ is (C ₅ -C ₃ o)alkyl. In certain embodiments, R ₂ is (C ₈ - C ₂₅ )alkyl. In certain embodiments, R ₂ is (Cio-C ₂₅ )alkyl. In certain embodiments, R ₂ is (C ₁₅ - C ₂₅ )alkyl. In certain embodiments, R ₂ is (Ci ₅ -C ₂ o)alkyl. In certain embodiments, R ₂ is (C ₅ - Ci ₅ )alkyl.

In certain embodiments, R ₂ is (C ₅ -C ₃ o)alkenyl. In certain embodiments, R ₂ is (Cx- C ₂₅ )alkenyl. In certain embodiments, R ₂ is (Cio-C ₂₅ )alkenyl. In certain embodiments, R ₂ is (Ci ₅ -C ₂₅ )alkenyl. In certain embodiments, R ₂ is (Ci ₅ -C ₂ o)alkenyl. In certain embodiments, R ₂ is (C ₅ -Ci ₅ )alkenyl.

In certain embodiments, R ₂ is (C ₅ -C ₃ o) mono-, di-, or tri-enyl. In certain embodiments,

R ₂ is (C ₈ -C ₂₅ ) mono-, di-, or tri-enyl. In certain embodiments, R ₂ is (Cio-C ₂₅ ) mono-, di-, or tri- enyl. In certain embodiments, R ₂ is (Cis-C ₂₅ ) mono-, di-, or tri-enyl. In certain embodiments, R ₂ is (Ci ₅ -C ₂ o) mono-, di-, or tri-enyl. In certain embodiments, R ₂ is (C ₅ -C ₁₅ ) mono-, di-, or tri- enyl.

In certain embodiments, R ₂ is:

In certain embodiments, R ₂ is:

5

In certain embodiments, a compound of formula (I) is selected from the group consisting

In certain embodiments, a compound of formula (I) is selected from the group consisting of:

In certain embodiments, a compound of formula (I) is selected from the group consisting of:

In certain embodiments, a compound of formula (I) is:

In certain embodiments, a compound of formula (I) is:

COMPOSITIONS OF THE INVENTION

Certain embodiments of the invention also provide a lubricating oil composition comprising a lubricating oil base stock and a compound of formula (I) as described herein. Lubricating oil base stocks are known in the art. For example, lubricating oil base stocks are described herein and in, e.g., US Patent Application Publication Number 2015-0344805, which is incorporated by reference in its entirety.

In certain embodiments, the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil.

As certain compounds of formula (I) may have different thermal decomposition temperatures, it may be advantageous to include a mixture of compounds of formula (I) in a lubricating oil composition described herein. Accordingly, in certain embodiments of the invention, a lubricating oil composition as described herein, comprises a mixture of compounds of formula (I) (e.g., two or more compounds of formula (I)). In certain embodiments of the invention, a lubricating oil composition as described herein, comprises a mixture of compounds of formula (I), wherein the compounds of formula (I) have different thermal decomposition temperatures.

In certain embodiments, the compound of formula (I) is present in an amount of from about 0.01 weight percent to about 5 weight percent, based on the total weight of the lubricating oil composition. In certain embodiments, the compound of formula (I) is present in an amount of from about 0.1 weight percent to about 5 weight percent, based on the total weight of the lubricating oil composition. In certain embodiments, the compound of formula (I) is present in an amount of from about 0.1 weight percent to about 2.5 weight percent, based on the total weight of the lubricating oil composition. In certain embodiments, the compound of formula (I) is present in an amount of from about 0.1 weight percent to about 1.5 weight percent, based on the total weight of the lubricating oil composition. In certain embodiments, the compound of formula (I) is present in an amount of from about 0.1 weight percent to about 1 weight percent, based on the total weight of the lubricating oil composition.

In certain embodiments, the lubricating oil base stock is present in an amount of from about 70 weight percent to about 95 weight percent, based on the total weight of the lubricating oil composition.

In certain embodiments, the lubricating oil composition further comprises one or more additional lubricating oil performance additives. Lubricating oil performance additives are known in the art. For example, lubricating oil performance additives are described herein and in, e.g., US Patent Application Publication Number 2015-0344805, which is incorporated by reference in its entirety. For example, in certain embodiments, the additional lubricating oil performance additive is selected from the group consisting of an anti-wear additive, viscosity modifier, other antioxidant, detergent, dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, friction modifier and anti-rust additive/inhibitor.

Certain embodiments of the invention provide a lubricating oil composition prepared by combining a lubricating oil base stock and a compound of formula (I) as described herein. Lubricating Oil Base Stocks

Lubricating oil compositions and formulations of the present disclosure include, but are not limited to, greases, gear oils, hydraulic oils, brake fluids, manual and automatic transmission fluids, other energy transferring fluids, tractor fluids, diesel compression ignition engine oils, gasoline spark ignition engine oils, turbine oils and the like. The lubricating base oil may be selected from the group consisting of natural oils, petroleum-derived mineral oils, synthetic oils and mixtures thereof. The lubricant to include in the disclosed compositions and formulations may be referred to as a“base fluid”,“base oil”,“lubricating oil” or“lubricant”.

A wide range of lubricating base oils is known in the art. Lubricating base oils that may be useful in the present disclosure are both natural oils, and synthetic oils, and unconventional oils (or mixtures thereof) can be used unrefined, refined, or rerefmed (the latter is also known as reclaimed or reprocessed oil). Unrefined oils are those obtained directly from a natural or synthetic source and used without added purification. These include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from an esterification process. Refined oils are similar to the oils discussed for unrefined oils except refined oils are subjected to one or more purification steps to improve at least one lubricating oil property. One skilled in the art is familiar with many purification processes. These processes include solvent extraction, secondary distillation, acid extraction, base extraction, filtration, and percolation. Rerefmed oils are obtained by processes analogous to refined oils but using an oil that has been previously used as a feed stock.

Groups I, II, III, IV and V are broad base oil stock categories developed and defined by the American Petroleum Institute (API Publication 1509; www.API.org to create guidelines for lubricant base oils. Group I base stocks have a viscosity index of from 80 to 120 and contain greater than 0.03% sulfur and/or less than 90% saturates. Group II base stocks have a viscosity index of from 80 to 120, and contain less than or equal to 0.03% sulfur and greater than or equal to 90% saturates. Group III stocks have a viscosity index greater than 120 and contain less than or equal to 0.03% sulfur and greater than 90% saturates. Group IV includes polyalphaolefms (PAO). Group V base stock includes base stocks not included in Groups I-IV. The table below summarizes properties of each of these five groups.

Natural oils include animal oils, vegetable oils (castor oil and lard oil, for example), and mineral oils. Animal and vegetable oils possessing favorable thermal oxidative stability can be used. Of the natural oils, mineral oils are a specific embodiment. Mineral oils vary widely as to their crude source, for example, as to whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful. Natural oils vary also as to the method used for their production and purification, for example, their distillation range and whether they are straight run or cracked, hydrorefmed, or solvent extracted.

Group II and/or Group III hydroprocessed or hydrocracked base stocks, including synthetic oils such as polyalphaolefms, alkyl aromatics and synthetic esters are also well known base stock oils.

Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oils such as polymerized and interpolymerized olefins (polybutylenes, polypropylenes, propylene isobutylene copolymers, ethylene-olefin copolymers, and ethyl ene-alphaolefm copolymers, for example). Polyalphaolefm (PAO) oil base stocks are commonly used synthetic hydrocarbon oil. By way of example, PAOs derived from C ₆ , C ₈ , Cio, C12, Ci ₄ olefins or mixtures thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064; and 4,827,073.

The number average molecular weights of the PAOs, which are known materials and generally available on a major commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical Company, BP, and others, typically vary from 250 to 3,000, although PAO's may be made in viscosities up to 100 cSt (l00°C). The PAOs are typically comprised of relatively low molecular weight hydrogenated polymers or oligomers of alphaolefms which include, but are not limited to, C ₂ to C32 alphaolefms with the C ₈ to Ci ₆ alphaolefms, such as 1 -hexene, l-octene, l-decene, l-dodecene and the like, being specific embodiments. Specific polyalphaolefms are poly- 1 -hexene, poly-l-octene, poly-l-decene and poly-l-dodecene and mixtures thereof and mixed olefin-derived polyolefins. However, the dimers of higher olefins in the range of Ci ₄ to Ci ₈ may be used to provide low viscosity base stocks of acceptably low volatility. Depending on the viscosity grade and the starting polymer (e.g., oligomer), the PAOs may be predominantly turners and tetramers of the starting olefins, with minor amounts of the higher polymers, having a viscosity range of 1.5 to 12 cSt. PAO fluids of particular use may include 3.0 cSt, 3.4 cSt, and/or 3.6 cSt and combinations thereof. Bi- modal mixtures of PAO fluids having a viscosity range of 1.5 to about 100 cSt or to about 300 cSt may be used if desired.

The PAO fluids may be conveniently made by the polymerization of an alphaolefin in the presence of a polymerization catalyst such as the Friedel-Crafts catalysts including, for example, aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. For example the methods disclosed by U.S. Pat. No. 4,149,178 or 3,382,291 may be conveniently used herein. Other descriptions of PAO synthesis are found in the following U.S. Pat. Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the Ci ₄ to C ₁₈ olefins are described in U.S. Pat. No. 4,218,330.

Other useful lubricant oil base stocks include wax isomerate base stocks and base oils, comprising hydroisomerized waxy stocks (e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker bottoms, etc.), hydroisomerized Fischer-Tropsch waxes, Gas-to-Liquids (GTL) base stocks and base oils, and other wax isomerate hydroisomerized base stocks and base oils, or mixtures thereof Fischer-Tropsch waxes, the high boiling point residues of Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with very low sulfur content. The hydroprocessing used for the production of such base stocks may use an amorphous

hydrocracking/hydroisomerization catalyst, such as one of the specialized lube hydrocracking (LHDC) catalysts or a crystalline hydrocracking/hydroisomerization catalyst, specifically a zeolitic catalyst. For example, one useful catalyst is ZSM-48 as described in U.S. Pat. No.

5,075,269, the disclosure of which is incorporated herein by reference in its entirety. Processes for making hydrocracked/hydroisomerized distillates and hydrocracked/hydroisomerized waxes are described, for example, in U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and 1,390,359. Each of the aforementioned patents is incorporated herein in their entirety. Particular processes are described in European Patent Application Nos. 464546 and 464547, which are also incorporated herein by reference. Processes using Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172 and 4,943,672, the disclosures of which are incorporated herein by reference in their entirety.

Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and other wax- derived hydroisomerized (wax isomerate) base oils may be advantageously used in the instant disclosure, and may have useful kinematic viscosities at l00°C of 3 cSt to 50 cSt, specifically 3 cSt to 30 cSt, more specifically 3.5 cSt to 25 cSt, as exemplified by GTL 4 with kinematic viscosity of 4.0 cSt at l00°C and a viscosity index of 141. These Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and other wax-derived hydroisomerized base oils may have useful pour points of -20° C or lower, and under some conditions may have advantageous pour points of -25° C or lower, with useful pour points of -30° C to -40° C or lower. Useful compositions of Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and wax-derived hydroisomerized base oils are recited in U.S. Pat. Nos. 6,080,301; 6,090,989, and 6,165,949 for example, and are incorporated herein in their entirety by reference.

The hydrocarbyl aromatics can be used as base oil or base oil component and can be any hydrocarbyl molecule that contains at least 5% of its weight derived from an aromatic moiety such as a benzenoid moiety or naphthenoid moiety, or their derivatives. These hydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, alkylated thiodiphenol, and the like. The aromatic can be mono-alkylated, dialkylated, polyalkylated, and the like. The aromatic can be mono- or poly-functionalized. The hydrocarbyl groups can also be comprised of mixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl groups and other related hydrocarbyl groups. The hydrocarbyl groups can range from C ₆ up to C ₆ o with a range of Cx to C20 as a specific embodiment. A mixture of hydrocarbyl groups may be used in a specific embodiment, and up to three such substituents may be present.

The hydrocarbyl group can optionally contain sulfur, oxygen, and/or nitrogen containing substituents. The aromatic group can also be derived from natural (petroleum) sources, provided at least 5% of the molecule is comprised of an above-type aromatic moiety. Viscosities at l00°C of about 3 cSt to about 50 cSt are specific embodiments, with viscosities of about 3.4 cSt to about 20 cSt often being more specific embodiments for the hydrocarbyl aromatic component.

In one embodiment, an alkyl naphthalene where the alkyl group is primarily comprised of 1- hexadecene is used. Other alkylates of aromatics can be advantageously used. Naphthalene or methyl naphthalene, for example, can be alkylated with olefins such as octene, decene, dodecene, tetradecene or higher, mixtures of similar olefins, and the like. Useful concentrations of hydrocarbyl aromatic in a lubricant oil composition can be 2% to 25%, specifically 4% to 20%, and more specifically 4% to 15%, depending on the application.

Alkylated aromatics such as the hydrocarbyl aromatics of the present disclosure may be produced by well-known Friedel-Crafts alkylation of aromatic compounds. See Friedel-Crafts and Related Reactions, Olah, G. A. (ed.), Inter-science Publishers, New York, 1963. For example, an aromatic compound, such as benzene or naphthalene, is alkylated by an olefin, alkyl halide or alcohol in the presence of a Friedel-Crafts catalyst. See Friedel-Crafts and Related Reactions, Vol. 2, part 1, chapters 14, 17, and 18, See Olah, G. A. (ed.), Inter-science Publishers, New York, 1964. Many homogeneous or heterogeneous, solid catalysts are known to one skilled in the art. The choice of catalyst depends on the reactivity of the starting materials and product quality requirements. For example, strong acids such as AlCh, BF3, or HF may be used. In some cases, milder catalysts such as FeCh or SnCl ₄ may be used in certain embodiments. Newer alkylation technology uses zeolites or solid super acids.

Esters comprise a useful base stock. Additive solvency and seal compatibility

characteristics may be secured by the use of esters such as the esters of dibasic acids with monoalkanols and the polyol esters of monocarboxylic acids. Esters of the former type include, for example, the esters of dicarboxylic acids such as phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc., with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types of esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

Particularly useful synthetic esters may be those which are obtained by reacting one or more polyhydric alcohols, for example, the hindered polyols (such as the neopentyl polyols, e.g., neopentyl glycol, trimethylol ethane, 2-methyl-2-propyl-l, 3 -propanediol, trimethylol propane, pentaerythritol and dipentaerythritol) with alkanoic acids containing at least 4 carbon atoms, specifically C ₅ to C ₃ o acids such as saturated straight chain fatty acids including caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid, or the corresponding branched chain fatty acids or unsaturated fatty acids such as oleic acid, or mixtures of any of these materials.

Suitable synthetic ester components include the esters of trimethylol propane, trimethylol butane, trimethylol ethane, pentaerythritol and/or dipentaerythritol with one or more

monocarboxylic acids containing from 5 to 10 carbon atoms. These esters are widely available commercially, for example, the Mobil P-41 and P-51 esters of ExxonMobil Chemical Company.

Also useful are esters derived from renewable material such as coconut, palm, rapeseed, soy, sunflower and the like. These esters may be monoesters, di-esters, polyol esters, complex esters, or mixtures thereof. These esters are widely available commercially, for example, the Mobil P-51 ester of ExxonMobil Chemical Company.

Engine oil formulations containing renewable esters are included in this disclosure. For such formulations, the renewable content of the ester is typically greater than 70 weight percent, more than 80 weight percent, or more than 90 weight percent. Renewable esters can be used in combination with a friction modifier mixture.

Other useful fluids of lubricating viscosity include non-conventional or unconventional base stocks that have been processed, such as catalytically, or synthesized to provide high performance lubrication characteristics.

Non-conventional or unconventional base stocks/base oils include one or more of a mixture of base stock(s) derived from one or more Gas-to-Li quids (GTL) materials, as well as isomerate/isodewaxate base stock(s) derived from natural wax or waxy feeds, mineral and or non-mineral oil waxy feed stocks such as slack waxes, natural waxes, and waxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal crackates, or other mineral, mineral oil, or even non-petroleum oil derived waxy materials such as waxy materials received from coal liquefaction or shale oil, and mixtures of such base stocks.

GTL materials are materials that are derived via one or more synthesis, combination, transformation, rearrangement, and/or degradation/deconstructive processes from gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks such as hydrogen, carbon dioxide, carbon monoxide, water, methane, ethane, ethylene, acetylene, propane, propylene, propyne, butane, butylenes, and butynes. GTL base stocks and/or base oils are GTL materials of lubricating viscosity that are generally derived from

hydrocarbons; for example, waxy synthesized hydrocarbons, that are themselves derived from simpler gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks. GTL base stock(s) and/or base oil(s) include oils boiling in the lube oil boiling range (1) separated/fractionated from synthesized GTL materials such as, for example, by distillation and subsequently subjected to a final wax processing step which involves either or both of a catalytic dewaxing process, or a solvent dewaxing process, to produce lube oils of reduced/low pour point; (2) synthesized wax isomerates, comprising, for example,

hydrodewaxed or hydroisomerized cat and/or solvent dewaxed synthesized wax or waxy hydrocarbons; (3) hydrodewaxed or hydroisomerized cat and/or solvent dewaxed Fischer- Tropsch (F-T) material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possible analogous oxygenates); specifically hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxing dewaxed F-T waxy hydrocarbons, or hydrodewaxed or hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T waxes, or mixtures thereof.

GTL base stock(s) and/or base oil(s) derived from GTL materials, especially,

hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxed wax or waxy feed, specifically F-T material derived base stock(s) and/or base oil(s), are characterized typically as having kinematic viscosities at 100° C of from 2 mm ² /s to 50 mm ² /s (ASTM D445). They are further characterized typically as having pour points of -5° C to -40° C or lower (ASTM D97). They are also characterized typically as having viscosity indices of 80 to 140 or greater (ASTM D2270).

In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monocycloparaffms and multicycloparaffms in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e., cycloparaffm) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than 10 ppm, and more typically less than 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, is essentially nil. In addition, the absence of phosphorous and aromatics make this materially especially suitable for the formulation of low SAP products.

The term GTL base stock and/or base oil and/or wax isomerate base stock and/or base oil is to be understood as embracing individual fractions of such materials of wide viscosity range as recovered in the production process, mixtures of two or more of such fractions, as well as mixtures of one or two or more low viscosity fractions with one, two or more higher viscosity fractions to produce a blend wherein the blend exhibits a target kinematic viscosity. The GTL material, from which the GTL base stock(s) and/or base oil(s) is/are derived is, e.g., an F-T material (i.e., hydrocarbons, waxy hydrocarbons, wax).

In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monocycloparaffms and multicycloparaffms in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e., cycloparaffm) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) and hydrodewaxed, or hydroisomerized/cat (and/or solvent) dewaxed base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than 10 ppm, and more typically less than 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, is essentially nil. In addition, the absence of phosphorous and aromatics make this material especially suitable for the formulation of low sulfur, sulfated ash, and phosphorus (low SAP) products.

Base oils for use in the formulated lubricating oils useful in the present disclosure are any of the variety of oils corresponding to API Group I, Group II, Group III, Group IV, and Group V oils and mixtures thereof, specifically API Group II, Group III, Group IV, and Group V oils and mixtures thereof, more specifically the Group III to Group V base oils due to their exceptional volatility, stability, viscometric and cleanliness features. Minor quantities of Group I stock, such as the amount used to dilute additives for blending into formulated lube oil products, can be tolerated but should be kept to a minimum, i.e. amounts only associated with their use as diluent/carrier oil for additives used on an“as-received” basis. In certain embodiments, the Group II stock may be in the higher quality range associated with that stock, i.e. a Group II stock having a viscosity index in the range 100 < VI < 120.

The lubricating base oil or base stock constitutes the major component of the lubricating oil composition of the present disclosure. One specific lubricating oil base stock for the inventive lubricating oil compositions and the inventive methods described herein is a Group I base stock that is included in the formulated oil at from 75 to 95 wt %, or from 80 to 90 wt %, or from 82 to 88 wt %. Another particular lubricating oil base stock for the inventive lubricating oil compositions and the inventive methods described herein is a combination of a Group III, Group IV and Group V base stock wherein the combination is included in the formulated oil at from 75 to 95 wt %, or from 80 to 90 wt %, or from 82 to 88 wt %. In this form, the Group III base stock is included at from 30 to 35 wt % or from 32 to 33 wt %, the Group IV base stock at from 45 to 55 wt % or from 48 to 52 wt %, and the Group V base stock at from 0 to 5 wt %, or from 2 to 4 wt %.

Examples of Group III base stocks are GTL and Yubase Plus (hydroprocessed base stock). Examples of Group V base stocks include alkylated naphthalene, synthetic esters and combinations thereof.

In some embodiments, the base oils or base stocks described above have a kinematic viscosity, according to ASTM standards, of about 2.5 cSt to about 12 cSt (or mm ² /s) at l00°C, of about 2.5 cSt to about 9 cSt (or mm ² /s) at l00°C, of about 4 cSt to about 8 cSt (or mm ² /s) at l00°C, or of about 4 cSt to about 6 cSt (or mm ² /s) at l00°C. In other embodiments, base stocks may have a kinematic viscosity of up to about 100 cSt, about 150 cSt, about 200 cSt, about 250 cSt or about 300 cSt at l00°C.

Lubricating oils and base stocks are disclosed for example in ETS. Pub. Nos.

20170211007, 20150344805 and 2015322367.

The lubricating oils of the disclosure may contain one or more further additives. Further additives may be present, in each case, from about 0.01 wt%, about 0.1, about 0.5 or about 1 wt% to about 2 wt%, about 5, about 7, about 8, about 10, about 14, about 17, about 20, about 22 or about 25 wt%, based on the total weight of the lubricating oil formulation.

The formulated lubricating oil useful in the present disclosure may additionally contain one or more of the other commonly used lubricating oil performance additives including but not limited to antiwear agents, dispersants, other detergents, corrosion inhibitors, rust inhibitors, metal deactivators, extreme pressure additives, anti-seizure agents, wax modifiers, viscosity index improvers, viscosity modifiers, fluid-loss additives, seal compatibility agents, organic metallic friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others. For a review of many commonly used additives, see Klamann in Lubricants and Related Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0.

Reference is also made to“Lubricant Additives” by M. W. Ranney, published by Noyes Data Corporation of Parkridge, N J (1973); see also U.S. Pat. No. 7,704,930, the disclosure of which is incorporated herein in its entirety. These additives are commonly delivered with varying amounts of diluent oil that may range from 5 weight percent to 50 weight percent. The types and quantities of performance additives used in combination with the instant disclosure in lubricant compositions are not limited by the examples shown herein as

illustrations.

Antiwear Additives

A metal alkylthiophosphate and more particularly a metal dialkyl dithio phosphate in which the metal constituent is zinc, or zinc dialkyl dithio phosphate (ZDDP) is a useful component of the lubricating oils of this disclosure. ZDDP can be derived from primary alcohols, secondary alcohols or mixtures thereof. ZDDP compounds generally are of the formula Zn[SP(S)(OR ¹ )(OR ² )] ₂ where R ¹ and R ² are Ci-Cis alkyl groups, e.g., C2-C12 alkyl groups. These alkyl groups may be straight chain or branched. Alcohols used in the ZDDP can be 2-propanol, butanol, secondary butanol, pentanols, hexanols such as 4-methyl-2-pentanol, n-hexanol, n- octanol, 2-ethyl hexanol, alkylated phenols, and the like. Mixtures of secondary alcohols or of primary and secondary alcohol may be used. Alkyl aryl groups may also be used.

Zinc dithiophosphates which are commercially available include secondary zinc dithiophosphates such as those available from for example, The Lubrizol Corporation under the trade designations“LZ 677A”,“LZ 1095” and“LZ 1371”, from for example Chevron Oronite under the trade designation“OLOA 262” and from for example Afton Chemical under the trade designation“HiTEC 7169”.

The ZDDP is typically used in amounts of from 0.4 weight percent to 1.2 weight percent, e.g., from 0.5 weight percent to 1.0 weight percent, or from 0.6 weight percent to 0.8 weight percent, based on the total weight of the lubricating oil, although more or less can often be used advantageously. In certain embodiments, the ZDDP is a secondary ZDDP and present in an amount of from 0.6 to 1.0 weight percent of the total weight of the lubricating oil.

Low phosphorus engine oil formulations are included in this disclosure. For such formulations, the phosphorus content is typically less than 0.12 weight percent, e.g., less than 0.10 weight percent or less than 0.085 weight percent. In certain embodiments, low phosphorus can be used in combination with the friction modifier mixture.

Viscosity Index Improvers

Viscosity index improvers (also known as VI improvers, viscosity modifiers, and viscosity improvers) can be included in the lubricant compositions of this disclosure. Viscosity index improvers provide lubricants with high and low temperature operability. These additives impart shear stability at elevated temperatures and acceptable viscosity at low temperatures.

Suitable viscosity index improvers include high molecular weight hydrocarbons, polyesters and viscosity index improver dispersants that function as both a viscosity index improver and a dispersant. Typical molecular weights of these polymers are between 10,000 to 1,500,000, more typically 20,000 to 1,200,000, and even more typically between 50,000 and 1,000,000.

Examples of suitable viscosity index improvers are linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes. Polyisobutylene is a commonly used viscosity index improver. Another suitable viscosity index improver is polymethacrylate (copolymers of various chain length alkyl methacrylates, for example), some formulations of which also serve as pour point depressants. Other suitable viscosity index improvers include copolymers of ethylene and propylene, hydrogenated block copolymers of styrene and isoprene, and polyacrylates (copolymers of various chain length acrylates, for example). Specific examples include styrene-isoprene or styrene-butadiene based polymers of 50,000 to 200,000 molecular weight.

Olefin copolymers, are commercially available from Chevron Oronite Company LLC under the trade designation“PARATONE®” (such as“PARATONE® 8921” and

“PARATONE® 8941”); from Afton Chemical Corporation under the trade designation “HiTEC®” (such as“HiTEC® 5850B”; and from The Lubrizol Corporation under the trade designation“Lubrizol® 7067C”. Polyisoprene polymers are commercially available from Infmeum International Limited, e.g. under the trade designation“SV200”; diene-styrene copolymers are commercially available from Infmeum International Limited, e.g. under the trade designation“SV 260”.

In an embodiment of this disclosure, the viscosity index improvers may be used in an amount of less than, e.g., 2.0 weight percent, less than 1.0 weight percent, or less than 0.5 weight percent, based on the total weight of the formulated oil or lubricating oil. Viscosity improvers are typically added as concentrates, in large amounts of diluent oil.

In another embodiment of this disclosure, the viscosity index improvers may be used in an amount of from, e.g., 0.25 to 2.0 weight percent, 0.15 to 1.0 weight percent, or 0.05 to 0.5 weight percent, based on the total weight of the formulated oil or lubricating oil. Detergents

Illustrative detergents useful in this disclosure include, for example, alkali metal detergents, alkaline earth metal detergents, or mixtures of one or more alkali metal detergents and one or more alkaline earth metal detergents. A typical detergent is an anionic material that contains a long chain hydrophobic portion of the molecule and a smaller anionic or oleophobic hydrophilic portion of the molecule. The anionic portion of the detergent is typically derived from an organic acid such as a sulfur acid, carboxylic acid, phosphorous acid, phenol, or mixtures thereof. The counterion is typically an alkaline earth or alkali metal.

Salts that contain a substantially stochiometric amount of the metal are described as neutral salts and have a total base number (TBN, as measured by ASTM D2896) of from 0 to 80. Many compositions are overbased, containing large amounts of a metal base that is achieved by reacting an excess of a metal compound (a metal hydroxide or oxide, for example) with an acidic gas (such as carbon dioxide). Useful detergents can be neutral, mildly overbased, or highly overbased. These detergents can be used in mixtures of neutral, overbased, highly overbased calcium salicylate, sulfonates, phenates and/or magnesium salicylate, sulfonates, phenates. The TBN ranges can vary from low, medium to high TBN products, including as low as 0 to as high as 600. Mixtures of low, medium, high TBN can be used, along with mixtures of calcium and magnesium metal based detergents, and including sulfonates, phenates, salicylates, and carboxylates. A detergent mixture with a metal ratio of 1, in conjunction of a detergent with a metal ratio of 2, and as high as a detergent with a metal ratio of 5, can be used. Borated detergents can also be used.

Alkaline earth phenates are another useful class of detergent. These detergents can be made by reacting alkaline earth metal hydroxide or oxide (CaO, Ca(OH) ₂ , BaO, Ba(OH) ₂ , MgO, Mg(OH) ₂ , for example) with an alkyl phenol or sulfurized alkylphenol. Useful alkyl groups include straight chain or branched C1-C30 alkyl groups, e.g., C ₄ -C ₂ o or mixtures thereof.

Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It should be noted that starting alkylphenols may contain more than one alkyl substituent that are each independently straight chain or branched and can be used from 0.5 to 6 weight percent. When a non-sulfurized alkylphenol is used, the sulfurized product may be obtained by methods well known in the art. These methods include heating a mixture of alkylphenol and sulfurizing agent (including elemental sulfur, sulfur halides such as sulfur dichloride, and the like) and then reacting the sulfurized phenol with an alkaline earth metal base.

Metal salts of carboxylic acids are also useful as detergents. These carboxylic acid detergents may be prepared by reacting a basic metal compound with at least one carboxylic acid and removing free water from the reaction product. These compounds may be overbased to produce the desired TBN level. Detergents made from salicylic acid are one class of detergents derived from carboxylic acids. Useful salicylates include long chain alkyl salicylates. One useful family of compositions is of the formula

wherein R _z is an alkyl group having 1 to 30 carbon atoms, q is an integer from 1 to 4, and M is an alkaline earth metal. Examples of R _z groups are alkyl chains of at least Cn, or Ci ₃ or greater. R _z may be optionally substituted with substituents that do not interfere with the detergent's function. In certain embodiments, M may be, calcium, magnesium, or barium. In certain embodiments, M is calcium.

Hydrocarbyl -substituted salicylic acids may be prepared from phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The metal salts of the hydrocarbyl-substituted salicylic acids may be prepared by double decomposition of a metal salt in a polar solvent such as water or alcohol.

Alkaline earth metal phosphates are also used as detergents and are known in the art.

Detergents may be simple detergents or what is known as hybrid or complex detergents. The latter detergents can provide the properties of two detergents without the need to blend separate materials. See U.S. Pat. No. 6,034,039.

Examples of detergents include calcium phenates, calcium sulfonates, calcium salicylates, magnesium phenates, magnesium sulfonates, magnesium salicylates and other related components (including borated detergents), and mixtures thereof. Examples of mixtures of detergents include magnesium sulfonate and calcium salicylate, magnesium sulfonate and calcium sulfonate, magnesium sulfonate and calcium phenate, calcium phenate and calcium salicylate, calcium phenate and calcium sulfonate, calcium phenate and magnesium salicylate, calcium phenate and magnesium phenate.

The detergent concentration in the lubricating oils of this disclosure can range from, e.g., 1.0 to 6.0 weight percent, 2.0 to 5.0 weight percent, or 2.0 weight percent to 4.0 weight percent, based on the total weight of the lubricating oil.

In one embodiment, a detergent mixture for the inventive lubricating oil compositions and the inventive methods described herein is a combination of an overbased calcium salicylate detergent and a magnesium sulfonate or a calcium sulfonate detergent. The overbased calcium salicylate detergent may be included in the formulated oil at from 0.5 to 2.5 wt %, or 1.0 to 2.0 wt %, or 1.2 to 1.8 wt %. The magnesium sulfonate or a calcium sulfonate detergent may also be included in the formulated oil at from 0.5 to 2.5 wt %, or 1.0 to 2.0 wt %, or 1.2 to 1.8 wt %.

As used herein, the detergent concentrations are given on an“as delivered” basis.

Typically, the active detergent is delivered with a process oil. The“as delivered” detergent typically contains from 20 weight percent to 80 weight percent, or from 40 weight percent to 60 weight percent, of active detergent in the“as delivered” detergent product.

Dispersants

During engine operation, oil-insoluble oxidation byproducts are produced. Dispersants help keep these byproducts in solution, thus diminishing their deposition on metal surfaces. Dispersants used in the formulation of the lubricating oil may be ashless or ash-forming in nature. In certain embodiments, the dispersant is ashless. So-called ashless dispersants are organic materials that form substantially no ash upon combustion. For example, non-metal- containing or borated metal-free dispersants are considered ashless. In contrast, metal-containing detergents discussed above form ash upon combustion.

Suitable dispersants typically contain a polar group attached to a relatively high molecular weight hydrocarbon chain. The polar group typically contains at least one element of nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

A particularly useful class of dispersants are the alkenylsuccinic derivatives, typically produced by the reaction of a long chain hydrocarbyl substituted succinic compound, usually a hydrocarbyl substituted succinic anhydride, with a polyhydroxy or polyamino compound. The long chain hydrocarbyl group constituting the oleophilic portion of the molecule which confers solubility in the oil, is normally a polyisobutylene group. Many examples of this type of dispersant are well known commercially and in the literature. Exemplary U.S. patents describing such dispersants are U.S. Pat. Nos. 3,172,892; 3,215,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersant are described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554;

3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882;

4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082;

5,705,458. A further description of dispersants may be found, for example, in European Patent Application No. 471 071, to which reference is made for this purpose.

Hydrocarbyl -substituted succinic acid and hydrocarbyl -substituted succinic anhydride derivatives are useful dispersants. In particular, succinimide, succinate esters, or succinate ester amides prepared by the reaction of a hydrocarbon-substituted succinic acid compound, e.g., having at least 50 carbon atoms in the hydrocarbon substituent, with at least one equivalent of an alkylene amine are particularly useful, although on occasion, having a hydrocarbon substituent between 20-50 carbon atoms can be useful.

Succinimides are formed by the condensation reaction between hydrocarbyl substituted succinic anhydrides and amines. Molar ratios can vary depending on the polyamine. For example, the molar ratio of hydrocarbyl substituted succinic anhydride to TEPA can vary from 1 : 1 to 5: 1. Representative examples are shown in U.S. Pat. Nos. 3,087,936; 3,172,892;

3,219,666; 3,272,746; 3,322,670; and U.S. Pat. Nos. 3,652,616, 3,948,800; and Canada Patent

No. 1,094,044.

Succinate esters are formed by the condensation reaction between hydrocarbyl substituted succinic anhydrides and alcohols or polyols. Molar ratios can vary depending on the alcohol or polyol used. For example, the condensation product of a hydrocarbyl substituted succinic anhydride and pentaerythritol is a useful dispersant.

Succinate ester amides are formed by condensation reaction between hydrocarbyl substituted succinic anhydrides and alkanol amines. For example, suitable alkanol amines include ethoxylated polyalkylpolyamines, propoxylated polyalkylpolyamines and

polyalkenylpolyamines such as polyethylene polyamines. One example is propoxylated hexamethylenediamine. Representative examples are shown in U.S. Pat. No. 4,426,305.

The molecular weight of the hydrocarbyl substituted succinic anhydrides used in the preceding paragraphs will typically range between 800 and 2,500 or more. The above products can be post-reacted with various reagents such as sulfur, oxygen, formaldehyde, carboxylic acids such as oleic acid. The above products can also be post reacted with boron compounds such as boric acid, borate esters or highly borated dispersants, to form borated dispersants generally having from 0.1 to 5 moles of boron per mole of dispersant reaction product.

Mannich base dispersants are made from the reaction of alkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which is incorporated herein by reference. Process aids and catalysts, such as oleic acid and sulfonic acids, can also be part of the reaction mixture.

Molecular weights of the alkylphenols range from 800 to 2,500. Representative examples are shown in U.S. Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

Typical high molecular weight aliphatic acid modified Mannich condensation products useful in this disclosure can be prepared from high molecular weight alkyl-substituted hydroxyaromatics or HNR ₂ group-containing reactants.

Hydrocarbyl substituted amine ashless dispersant additives are well known to one skilled in the art; see, for example, U.S. Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433,

3,822,209, and 5,084,197.

Examples of dispersants include borated and non-borated succinimides, including those derivatives from mono-succinimides, bis-succinimides, and/or mixtures of mono- and bis- succinimides, wherein the hydrocarbyl succinimide is derived from a hydrocarbylene group such as polyisobutylene having a Mn of from 500 to 5000, or from 1000 to 3000, or 1000 to 2000, or a mixture of such hydrocarbylene groups, often with high terminal vinylic groups. Other dispersants include succinic acid-esters and amides, alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives, and other related components. Such additives may be used in an amount of, e.g., 0.1 to 20 weight percent, 0.5 to 8 weight percent, or 0.5 to 4 weight percent. On an active ingredient basis, such additives may be used in an amount of 0.06 to 14 weight percent, such as 0.3 to 6 weight percent. The hydrocarbon portion of the dispersant atoms can range from C ₆ oto C ₄ oo, or from C ₇ oto C300, or from C ₇ oto C200. These dispersants may contain both neutral and basic nitrogen, and mixtures of both. Dispersants can be end-capped by borates and/or cyclic carbonates.

In one embodiment, the dispersant for the inventive lubricating oil compositions and the inventive methods described herein is a non-borated polyisobutenyl bis-succinimide (PIBSA) dispersant. The non-borated PIBSA dispersant may be included in the formulated oil at from 2.0 to 6.0 wt%, or 3.0 to 5.0 wt%, or 3.5 to 4.5 wt%.

As used herein, the dispersant concentrations are given on an“as delivered” basis. Typically, the active dispersant is delivered with a process oil. The“as delivered” dispersant typically contains from 20 weight percent to 80 weight percent, or from 40 weight percent to 60 weight percent, of active dispersant in the“as delivered” dispersant product.

Further Antioxidants

Antioxidants retard the oxidative degradation of base oils and additives during service. Such degradation may result in deposits on metal surfaces, the presence of sludge, or a viscosity increase in the lubricant. One skilled in the art knows a wide variety of oxidation inhibitors that are useful in lubricating oil compositions. See, Klamann in Lubricants and Related Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197, for example.

Useful antioxidants may include hindered phenols. These phenolic antioxidants may be ashless (metal-free) phenolic compounds or neutral or basic metal salts of certain phenolic compounds. Typical phenolic antioxidant compounds are the hindered phenolics which are the ones which contain a sterically hindered hydroxyl group, and these include those derivatives of dihydroxy aryl compounds in which the hydroxyl groups are in the o- or p-position to each other. Typical phenolic antioxidants may include the hindered phenols substituted with C ₆ + alkyl groups and the alkyl ene coupled derivatives of these hindered phenols. Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4- dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t- butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful hindered mono- phenolic antioxidants may include for example hindered 2,6-di-alkyl-phenolic propionic ester derivatives. Bis-phenolic antioxidants may also be advantageously used in combination with the instant disclosure. Examples of ortho-coupled phenols include: 2,2'-bis(4-heptyl-6-t-butyl- phenol); 2,2'-bis(4-octyl-6-t-butyl-phenol); and 2,2'-bis(4-dodecyl-6-t-butyl-phenol). Para- coupled bisphenols include for example 4,4'-bis(2,6-di-t-butyl phenol) and 4,4'-methylene- bis(2,6-di-t-butyl phenol).

Effective amounts of one or more catalytic antioxidants may also be used. The catalytic antioxidants comprise an effective amount of a) one or more oil soluble polymetal organic compounds; and, effective amounts of b) one or more substituted N,N'-diaryl-o- phenylenediamine compounds or c) one or more hindered phenol compounds; or a combination of both b) and c). Catalytic antioxidants are more fully described in U.S. Pat. No. 8,048,833, herein incorporated by reference in its entirety.

Non-phenolic oxidation inhibitors which may be used include aromatic amine antioxidants and these may be used either as such or in combination with phenolics. Typical examples of non-phenolic antioxidants may include: alkylated and non-alkylated aromatic amines such as aromatic monoamines of the formula R ⁸ R ⁹ R ¹⁰ N where R ⁸ is an aliphatic, aromatic or substituted aromatic group, R ⁹ is an aromatic or a substituted aromatic group, and R ¹⁰ is H, alkyl, aryl or R ^u S(0)xR ¹² where R ¹¹ is an alkylene, alkenylene, or aralkylene group, R ¹² is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1 or 2. The aliphatic group R ⁸ may contain from 1 to 20 carbon atoms, such as from 6 to 12 carbon atoms. The aliphatic group is a saturated aliphatic group. In certain embodiments, both R ⁸ and R ⁹ are aromatic or substituted aromatic groups, and the aromatic group may be a fused ring aromatic group such as naphthyl. Aromatic groups R ⁸ and R ⁹ may be joined together with other groups such as S.

Typical aromatic amines antioxidants have alkyl substituent groups of at least 6 carbon atoms. Examples of aliphatic groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups will not contain more than 14 carbon atoms. The general types of amine antioxidants useful in the present compositions include diphenyl amines, phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of two or more aromatic amines are also useful. Polymeric amine antioxidants can also be used. Particular examples of aromatic amine antioxidants useful in the present disclosure include: r,r'- dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and p- octylphenyl -alpha-naphthyl amine .

Sulfurized alkyl phenols and alkali or alkaline earth metal salts thereof also are useful antioxidants.

In certain embodiments, antioxidants may include hindered phenols, arylamines. These antioxidants may be used individually by type or in combination with one another. Such additives may be used in an amount of 0.01 to 5 weight percent, specifically 0.01 to 1.5 weight percent, more specifically zero to less than 1.5 weight percent, more specifically zero to less than 1 weight percent. Pour Point Depressants (PPDs)

Conventional pour point depressants (also known as lube oil flow improvers) may be added to the compositions of the present disclosure if desired. These pour point depressant may be added to lubricating compositions of the present disclosure to lower the minimum

temperature at which the fluid will flow or can be poured. Examples of suitable pour point depressants include polymethacrylates, polyacrylates, polyarylamides, condensation products of haloparaffm waxes and aromatic compounds, vinyl carboxylate polymers, and terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479; 2,666,746; 2,721,877; 2,721,878; and 3,250,715 describe useful pour point depressants and/or the preparation thereof. Such additives may be used in an amount of 0.01 to 5 weight percent, such as 0.01 to 1.5 weight percent.

Seal Compatibility Agents

Seal compatibility agents help to swell elastomeric seals by causing a chemical reaction in the fluid or physical change in the elastomer. Suitable seal compatibility agents for lubricating oils include organic phosphates, alkoxysulfonlanes (Cio alcohol, for example), aromatic esters, aromatic hydrocarbons, esters (butylbenzyl phthalate, for example), and polybutenyl succinic anhydride. Such additives may be used in an amount of 0.01 to 3 weight percent, such as 0.01 to 2 weight percent.

Antifoam Agents

Antifoam agents may advantageously be added to lubricant compositions. These agents retard the formation of stable foams. Silicones and organic polymers are typical antifoam agents. For example, polysiloxanes, such as silicon oil or polydimethyl siloxane, provide antifoam properties. Antifoam agents are commercially available and may be used in conventional minor amounts along with other additives such as demulsifiers; usually the amount of these additives combined is less than 1 weight percent and often less than 0.1 weight percent.

Inhibitors and Antirust Additives

Antirust additives (or corrosion inhibitors) are additives that protect lubricated metal surfaces against chemical attack by water or other contaminants. A wide variety of these are commercially available. One type of antirust additive is a polar compound that wets the metal surface, e.g., protecting it with a film of oil. Another type of antirust additive absorbs water by incorporating it in a water-in-oil emulsion so that only the oil touches the metal surface. Yet another type of antirust additive chemically adheres to the metal to produce a non-reactive surface. Examples of suitable additives include zinc dithiophosphates, metal phenolates, basic metal sulfonates, fatty acids and amines. Such additives may be used in an amount of 0.01 to 5 weight percent, such as 0.01 to 1.5 weight percent.

Friction Modifiers

A friction modifier is any material or materials that can alter the coefficient of friction of a surface lubricated by any lubricant or fluid containing such material(s). Friction modifiers, also known as friction reducers, or lubricity agents or oiliness agents, and other such agents that change the ability of base oils, formulated lubricant compositions, or functional fluids, to modify the coefficient of friction of a lubricated surface may be effectively used in combination with the base oils or lubricant compositions of the present disclosure if desired. Friction modifiers that lower the coefficient of friction are particularly advantageous in combination with the base oils and lube compositions of this disclosure.

Illustrative friction modifiers may include, for example, organometallic compounds or materials, or mixtures thereof. Illustrative organometallic friction modifiers useful in the lubricating oil formulations of this disclosure include, for example, molybdenum amine, molybdenum diamine, an organotungstenate, a molybdenum dithiocarbamate, molybdenum dithiophosphates, molybdenum amine complexes, molybdenum carboxylates, and the like, and mixtures thereof. Similar tungsten based compounds may be used. Other illustrative friction modifiers useful in the lubricating oil formulations of this disclosure include, for example, alkoxylated fatty acid esters, alkanolamides, polyol fatty acid esters, borated glycerol fatty acid esters, fatty alcohol ethers, and mixtures thereof.

Illustrative alkoxylated fatty acid esters include, for example, polyoxyethylene stearate, fatty acid polyglycol ester, and the like. These can include polyoxypropylene stearate, polyoxybutylene stearate, polyoxyethylene isosterate, polyoxypropylene isostearate,

polyoxyethylene palmitate, and the like.

Illustrative alkanolamides include, for example, lauric acid diethylalkanolamide, palmic acid diethylalkanolamide, and the like. These can include oleic acid diethyalkanolamide, stearic acid diethylalkanolamide, oleic acid diethylalkanolamide, polyethoxylated hydrocarbylamides, polypropoxylated hydrocarbylamides, and the like.

Illustrative polyol fatty acid esters include, for example, glycerol mono-oleate, saturated mono-, di-, and tri-glyceride esters, glycerol mono- stearate, and the like. These can include polyol esters, hydroxyl -containing polyol esters, and the like.

Illustrative borated glycerol fatty acid esters include, for example, borated glycerol mono-oleate, borated saturated mono-, di-, and tri-glyceride esters, borated glycerol mono- sterate, and the like. In addition to glycerol polyols, these can include trimethylolpropane, pentaerythritol, sorbitan, and the like. These esters can be polyol monocarboxylate esters, polyol dicarboxylate esters, and on occasion polyoltricarboxylate esters. In certain embodiments, they can be the glycerol mono-oleates, glycerol dioleates, glycerol trioleates, glycerol monostearates, glycerol distearates, and glycerol tristearates and the corresponding glycerol monopalmitates, glycerol dipalmitates, and glycerol tripalmitates, and the respective isostearates, linoleates, and the like. On occasion the glycerol esters can be used, as well as mixtures containing any of these. Ethoxylated, propoxylated, butoxylated fatty acid esters of polyols, especially using glycerol as underlying polyol can be used.

Illustrative fatty alcohol ethers include, for example, stearyl ether, myristyl ether, and the like. Alcohols, including those that have carbon numbers from C ₃ to C50, can be ethoxylated, propoxylated, or butoxylated to form the corresponding fatty alkyl ethers. The underlying alcohol portion can be stearyl, myristyl, C11 - C13 hydrocarbon, oleyl, isosteryl, and the like.

Useful concentrations of friction modifiers may range from 0.01 weight percent to 5 weight percent, or about 0.1 weight percent to about 2.5 weight percent, or about 0.1 weight percent to about 1.5 weight percent, or about 0.1 weight percent to about 1 weight percent.

Concentrations of molybdenum- containing materials are often described in terms of Mo metal concentration. Advantageous concentrations of Mo may range from 25 ppm to 700 ppm or more, and often with a range of 50-200 ppm. Friction modifiers of all types may be used alone or in mixtures with the materials of this disclosure. Often mixtures of two or more friction modifiers, or mixtures of friction modifier(s) with alternate surface active material(s), are also desirable.

When lubricating oil compositions contain one or more of the additives discussed above, the additive(s) are blended into the composition in an amount sufficient for it to perform its intended function. Typical amounts of such additives useful in the present disclosure are shown in the table below.

It is noted that many of the additives are shipped from the additive manufacturer as a concentrate, containing one or more additives together, with a certain amount of base oil diluents. Accordingly, the weight amounts in the table below, as well as other amounts mentioned herein, are directed to the amount of active ingredient (that is the non-diluent portion of the ingredient). The weight percent (wt%) indicated below is based on the total weight of the lubricating oil composition.

The foregoing additives are all commercially available materials. These additives may be added independently but are usually precombined in packages which can be obtained from suppliers of lubricant oil additives. Additive packages with a variety of ingredients, proportions and characteristics are available and selection of the appropriate package will take the requisite use of the ultimate composition into account.

The present antioxidant compositions can be introduced into the lubricating oil in manners known per se. The compounds are readily soluble in oils. They may be added directly to the lubricating oil or they can be diluted with a substantially inert, normally liquid organic diluent such as naphtha, benzene, toluene, xylene or a normally liquid oil or fuel to form an additive concentrate or masterbatch. Antioxidant concentrates may include base stocks, such as ester base stocks, as a diluent. In certain embodiments, antioxidant concentrates include solvents such as glymes, such as monomethyl tetraglyme. These concentrates generally contain from about 10% to about 90% by weight additive and may contain one or more other additional additives. The present antioxidant compositions may be introduced as part of an additive package in liquid or solid form.

METHODS OF USE

Typically, antioxidants retard the oxidative degradation of base oils during service. Such degradation may result in deposits on metal surfaces, the presence of sludge, or a viscosity increase in the lubricant. Accordingly, the addition of antioxidants to lubricant formulations can mitigate oxidative degradation, significantly enhancing the performance and overall lifetime of the lubricant.

Accordingly, certain embodiments of the invention provide a method for reducing the oxidative degradation of a lubricating oil composition, comprising adding to the lubricating oil composition a compound of formula (I) as described herein. In certain embodiments, the oxidative degradation is reduced (e.g., by at least about 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or more) as compared to a lubricating oil composition that does not comprise a compound of formula (I).

Certain embodiments of the invention also provide a method of preparing a lubricating oil composition having reduced oxidative degradation comprising combining a lubricating oil base stock and a compound of formula (I) as described herein, to provide a lubricating oil composition having reduced oxidative degradation. In certain embodiments, the oxidative degradation of the lubricating oil composition in a system is reduced (e.g., by at least about 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%,

85%, 90%, 95%, or more) as compared to a lubricating oil composition in a system that does not comprise a compound of formula (I).

Certain embodiments of the invention provide a method for extending the lifetime of a lubricating oil composition in a system (e.g., an engine or other mechanical component), comprising adding to the lubricating oil composition a compound of formula (I) as described herein. In certain embodiments, the lifetime of a lubricating oil composition in a system is longer as compared to the lifetime of a lubricating oil composition in a system that does not comprise a compound of formula (I). In certain embodiments, the lifetime of the lubricating oil composition is extended by at least about, e.g., 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or more, as compared to a corresponding lubricating oil

composition that does not comprise a compound of formula (I).

In certain embodiments, the lubricating oil composition comprises a lubricating oil base stock and the compound of formula (I) reduces the oxidative degradation of the lubricating oil base stock.

In certain embodiments, the lubricating oil composition further comprises one or more additional lubricating oil performance additives. In certain embodiments, the additional lubricating oil performance additive(s) is selected from the group consisting of an anti-wear additive, viscosity modifier, other antioxidant, detergent, dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, friction modifier and anti-rust additive/inhibitor.

CERTAIN DEFINITIONS

The following definitions are used, unless otherwise described: halo is fluoro, chloro, bromo, or iodo. Alkyl, alkanoyl, alkenyl, alkenoyl, etc. denote both straight and branched groups; but reference to an individual radical such as propyl embraces only the straight chain radical, a branched chain isomer such as isopropyl being specifically referred to.

It will be appreciated by those skilled in the art that compounds of the invention having a chiral center may exist in and be isolated in optically active and racemic forms. Some compounds may exhibit polymorphism. It is to be understood that the present invention encompasses any racemic, optically-active, polymorphic, or stereoisomeric form, or mixtures thereof, of a compound of the invention, which possess the useful properties described herein, it being well known in the art how to prepare optically active forms (for example, by resolution of the racemic form by recrystallization techniques, by synthesis from optically-active starting materials, by chiral synthesis, or by chromatographic separation using a chiral stationary phase.

When a bond in a compound formula herein is drawn in a non-stereochemical manner (e.g. flat), the atom to which the bond is attached includes all stereochemical possibilities.

When a bond in a compound formula herein is drawn in a defined stereochemical manner (e.g. bold, bold-wedge, dashed or dashed-wedge), it is to be understood that the atom to which the stereochemical bond is attached is enriched in the absolute stereoisomer depicted unless otherwise noted. In one embodiment, the compound may be at least 51% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 60% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 80% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 90% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 95 the absolute stereoisomer depicted. In another embodiment, the compound may be at least 99% the absolute stereoisomer depicted.

In one embodiment, the compound is not enriched in a single stereoisomer ( e.g ., a diastereomer or enantiomer) more than about 60%. In one embodiment, the compound is not enriched in a single stereoisomer (e.g., a diastereomer or enantiomer) more than about 51%.

Specific values listed below for radicals, substituents, and ranges, are for illustration only; they do not exclude other defined values or other values within defined ranges for the radicals and substituents.

For example, (Cio-C ₂ 5)alkyl can be, (Ci)alkyl, (C ₂ )alkyl, (C ₃ )alkyl, (C ₄ )alkyl, (Cs)alkyl, (C ₆ )alkyl, (C ₇ )alkyl, (Cs)alkyl, (Ci>)alkyl, (Cio)alkyl, (Cn)alkyl, (Ci ₂ )alkyl, (Ci ₃ )alkyl,

(Ci ₄ )alkyl, (Cis)alkyl, (Ci ₆ )alkyl, (Cn)alkyl, (C ix)alkyl, (Ci9)alkyl, (C ₂₀ )alkyl, (C _2i )alkyl, (C ₂₂ )alkyl, (C ₂₃ )alkyl, (C ₂₄ )alkyl, (C ₂₅ )alkyl, (C ₂₆ )alkyl, (C ₂₇ )alkyl, (C ₂₈ )alkyl, (C ₂ 9)alkyl or (C ₃₀ )alkyl. In certain embodiments, (Cio-C ₂₅ )alkyl can be, e.g., decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadeyl, octadeyl, nonadecyl, eicosyl, heneicosyl, docosyJ, tricosyi, tetraeosyl or pentaeosyl.

As described herein, (Ci-C ₂ o)alkanoyl is ((Ci-Ci ₉ )alkyl)-C(=0)-. For example, (Ci- C ₆ )alkanoyl can be acetyl, propanoyl or butanoyl.

As described herein, (C5-C ₃ o)alkenyl is a C ₅ to C ₃ o branched or unbranched carbon chain that has 1 or more (e.g., 1, 2, 3 or 4) double bonds. For example, (Cio-C ₂₅ )alkenyl can be, (Ci)alkenyl, (C ₂ )alkenyl, (C ₃ )alkenyl, (C ₄ )alkenyl, (Cs)alkenyl, (C ₆ )alkenyl, (C ₇ )alkenyl, (C ₈ )alkenyl, (C9)alkenyl, (Cio)alkenyl, (Cn)alkenyl, (Ci ₂ )alkenyl, (Ci ₃ )alkenyl, (Ci ₄ )alkenyl, (Ci ₅ )alkenyl, (Ci ₆ )alkenyl, (Ci ₇ )alkenyl, (Cix)alkenyl, (Ci9)alkenyl, (C ₂₀ )alkenyl, (C _2i )alkenyl, (C ₂₂ )alkenyl, (C ₂₃ )alkenyl, (C ₂₄ )alkenyl, (C ₂₅ )alkenyl, (C ₂₆ )alkenyl, (C ₂₇ )alkenyl, (C ₂ x)alkenyl, (C ₂ 9)alkenyl or (C ₃₀ )alkenyl. In certain embodiments, (Cio-C ₂₅ )alkenyl is 3-decen-l-yl, 4- undecen-l-yl, 3-dodecen-l-yl, 5-tridecen-l-yl, 4-tetradecen-l-yl, 6-pentadecen-l-yl, 7- hexadecen-l-yl, 3-heptadecen-l-yl, 6-octadecen-l-yl, 4-nonadecen-l-yl, 5-eicosen-l-yl, 7- henei cosen- 1-yl, 8-docosen-l -yl, 4-tricosen-l-yl, 3-tetracosen-l-yl or 4-pentacosen-l-yl. (Cio- C ₂ 5)alkenyl can also be, e.g., 3,6-octadecen-l-yl or 3,7,l l-trimethyl-2,6,l0-dodecatriene-l-yl.

As described herein, (C3-C ₂ o)alkenoyl is (C ₂ -Ci ₉ )alkenyl)-C(=0)-, wherein the (C ₂ - Ci9)alkenyl is a C ₂ to C19 branched or unbranched carbon chain that has 1 or more (e.g., 1, 2, 3 or 4) double bonds.

As described herein, (Ci-C ₆ )alkoxy includes methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, /c/V-butoxy, pentoxy, isopentoxy, and hexyloxy.

As used herein the term "salt" includes base addition, acid addition and quaternary salts. Compounds of the invention which are acidic can form salts, with bases such as alkali metal hydroxides, e.g. sodium and potassium hydroxides; alkaline earth metal hydroxides e.g. calcium, barium and magnesium hydroxides; with organic bases e.g. N-methyl-D-glucamine, choline tris(hydroxymethyl)amino-methane, L-arginine, L-lysine, N-ethyl piperidine, dibenzylamine and the like.

In cases where compounds are sufficiently acidic, a salt of a compound of formula I can be useful as an intermediate for isolating or purifying a compound of formula I.

All numerical values within the detailed description and the claims herein are modified by“about” or“approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

As used herein the phrase "other mechanical component" includes an electric vehicle component, a hybrid vehicle component, a power train, a driveline, a transmission, a gear, a gear train, a gear set, a compressor, a pump, a hydraulic system, a bearing, a bushing, a turbine, a piston, a piston ring, a cylinder liner, a cylinder, a cam, a tappet, a lifter, a gear, a valve, or a bearing including a journal, a roller, a tapered, a needle, and a ball bearing.

CERTAIN METHODS FOR PREPARING COMPOUNDS OF FORMULA (I)

Generally, compounds of formula (I), as well as synthetic intermediates that can be used for preparing compounds of formula (I), can be prepared as illustrated in the following Schemes and Examples.

Scheme 1.

HO - As shown in Scheme 1, intermediate (101) can be converted to a compound of formula (I), wherein R may be Ri or R ₂ , and wherein Ri, R ₂ andL are defined as described herein.

Scheme 2.

^R, >-' H + " ^o ° ^H - -

(102)

As shown in Scheme 2, 102 can be converted to a compound of formula (I), wherein Ri, R ₂ and L are defined as described herein.

Scheme 3.

( ¹⁰³ ) (!)

As shown in Scheme 3, 103 can be converted to a compound of formula (I), wherein Ri, R ₂ and L are defined as described herein.

Scheme 4.

As shown in Scheme 4, the diacid (104) can be converted to a compound of formula (la), wherein R may be Ri or R ₂ , and wherein Ri, R ₂ and L are defined as described herein.

The invention will now be illustrated by the following non-limiting Examples. EXAMPLES

Described herein is the development of lubricant additives using bifunctional water- soluble antioxidants. Certain bioactives, linkers and intermediates, which may be used to generate compounds of the invention, are shown in Table 1 below. For example, moieties that can potentially withstand higher temperatures may be used to generate diacid intermediates. Oil- solubility may then be subsequently enhanced by conjugating the diacids to long-chain alcohols (or fatty acids) (see, e.g., Table 1 and Figure 1). Oligomeric/polymeric systems that incorporate the antioxidant within a polymer backbone may also be further generated. Such oligomers/polymers would allow for enhanced controlled release of active antioxidants over a period of time.

The molecular structure/composition of compounds of the invention may be determined via nuclear magnetic resonance (NMR) and infrared (IR) spectroscopies. Molecular weight may be determined via mass spectrometry, or in the case of polymeric materials, gel permeation chromatography (GPC). Thermal properties, including glass transition temperature (T _g ) and melting temperature (T _m ), may be determined via differential scanning calorimetry (DSC) (e.g, pressurized), whereas decomposition temperatures (T _d ) may be determined via

thermogravimetric analysis (TGA) (e.g, pressurized). T _d measurements may be conducted in the presence of air or Ar atmosphere using a 10 °C/min temperature ramp, in addition to isothermal testing at 100 °C for 24 h. Solubility of a compound of the invention may be assessed in oil formulations (e.g., PAO) at 0.5 to 2 % w/w. Additionally, antioxidant activity may be assessed using free radical scavenging activity as evaluated by a 2,2-diphenyl- l-picrylhydrazyl (DPPH) antioxidant assay, wherein the compound is incubated in media in a DPPH solution and monitored by UV-spectroscopy (see, R. Scherer, H. T. Godoy, Food Chem. 2009, 112, 654).

Table 1. Certain bioactives (e.g. antioxidants), linkers and intermediates, which may be used to generate compounds of the invention, and their T _m /T _d data, which are ranked according to thermal transition temperatures.

² Faig, et al., Macromolecular Chemistry and Physics 2016, 217 (1), 108-114. ⁴ Prudencio, et al.,

Macromolecules 2005, 38 (16), 6895-6901. ⁵ Schmeltzer, et al., Polymer Bulletin 2006, 57 (3),

281-291. ⁷ Pubchem database CID 289. ⁸ Pubchem database CID 3840. ⁹ Johnson, M. L.;

Uhrich, K. E., ./. Biomed. Mater. Res. Part A 2009, 91A (3), 671-678. ¹⁰ Pubchem database CID

445858. ^u Fiddler, et al., J. Agric. Food Chem., 1967, 15 (5), 757-761. ¹² Chen, et al., Food

Chem. 2014, 755, 81-86. ¹³ Wichitnithad, et al., Molecules 201 1, 16 , 1888-1900. ¹⁴ Pubchem database CID 743. ¹⁵ OECD database CAS: 124-04-9. ¹⁶ Sigma-aldrich Product information CAS: 110-15-6. ¹⁷ Pubchem database CID 971.

The synthesis of intermediates FA+adipoly diacid (3), FA+ox diacid (6) and SA+adipoyl diacid (9) is shown below, along with the synthesis of certain diesters of formula (I) (see, Examples 1-16). As described in Example 17, the thermal stability and solubility of these compounds was investigated, as well as the preparation and characterization of certain formulations comprising these compounds.

Chemical reagents were purchased from Aldrich, TCI, or Oakwood and used as received. All air and water sensitive reactions were performed under argon atmosphere. ¾ and ¹³ C NMR spectra were recorded on a Bruker Avance 300 (300 MHz). All chemical shifts were reported in parts per million (ppm). 'H NMR chemical shifts were referenced to TMS (0 ppm) or CHCh (7.26 ppm). Thermal gravity analyses (TGA) were carried out on a TA Instrument Q500 analyzer. TGA curves were collected under air or argon at a heating speed of 10 °C min ¹ .

EXAMPLE 1

Synthesis of Compound (3) (i.e., FA - adipoyl diacid). Compound (3) was produced as described in Ouimet et ak, Biomacromolecules, 14(3): 854-861 (2013). T _d = 239 °C. EXAMPLE 2

Synthesis of Compound (4) ( i.e CsCio). In a 100 mL round-bottom-flask, 450 mg FA+adipoly diacid (3), 540 mg 2-octyl- l-dodecanol and 584 mg 4-(dimethylamino)pyridinium 4-toluenesulfonate (DPTS) were dissolved in 20 mL anhydrous methylene dichloride. 2 mL DCC solution (1M, in methylene dichloride) were added dropwisely. After being stirred at room temperature for 24 hours, the reaction was kept in a freezer for 3 hours for byproduct precipitation. After filtration, the solvent of filtrate was removed in vacuo. Crude product was purified on silica gel via flash chromatography using 4: 1 hexane/ethyl acetate as eluent. The product was obtained as a colorless oil.

C ₈ Cio ¹ HNMR (300 MHz, CDCh): d 7.65 (d, 2H, J= 16 Hz, R-CH = CH-R), 7.11-7.03 (m, 6H, Ar-H), 6.41 (d, 2H, J= 16 Hz, R-CH = CH-R), 4.12 (d, 4H, J= 5.7 Hz), 3.86 (s, 6H, OMe), 2.67 (t, 4H, J= 5.4 Hz), 1.33-1.26 (m, 66H), 0.88 (t, 6H, J= 6.3 Hz, CH ₃ ). T _d = 322 °C.

EXAMPLE 3

Synthesis of Compound (5) ( i.e C10C12). A procedure similar to that used for compound (4) was used to synthesize C10C12 (5), which resulted in the production of a white solid.

¹ HNMR (300 MHz, CDCb): d 7.65 (d, 2H, J= 16 Hz, R-CH = CH-R), 7.11-7.03 (m, 6H, Ar-H), 6.41 (d, 2H, J= 16 Hz, R-CH = CH-R), 4.12 (d, 4H, J= 5.7 Hz), 3.86 (s, 6H, OMe), 2.67 (t, 4H, J= 5.4 Hz), 1.33-1.26 (m, 84H), 0.88 (t, 12H, J= 6.3 Hz, CH ₃ ). T _d = 227 °C.

EXAMPLE 4

Synthesis of Compound (10). A procedure similar to that used for compound (4) was used to synthesize (10), which resulted in the production of a white solid.

¹ HNMR (300 MHz, CDCh): d 7.65 (d, 2H, J= 16 Hz, R-CH = CH-R), 7.11-7.03 (m, 6H, Ar-H), 6.41 (d, 2H, J= 16 Hz, R-CH = CH-R), 4.20 (t, 4H, J= 6 Hz), 3.86 (s, 6H, OMe), 2.67 (t, 4H, J= 5.4 Hz), 1.33-1.25 (m, 24H), 0.88 (t, 12H, J= 6.3 Hz, CH ₃ ).

EXAMPLE 5

Synthesis of Compound (11). A procedure similar to that used for compound (4) was used to synthesize (11), which resulted in the production of a white solid.

¹ HNMR (300 MHz, CDCh): d 7.65 (d, 2H, J= 16 Hz, R-CH = CH-R), 7.11-7.03 (m, 6H, Ar-H), 6.41 (d, 2H, J= 16 Hz, R-CH = CH-R), 4.20 (t, 4H, J= 6 Hz), 3.86 (s, 6H, OMe), 2.67 (t, 4H, J= 5.4 Hz), 1.33-1.25 (m, 32H), 0.88 (t, 6H, J= 6.3 Hz, CH ₃ ).

EXAMPLE 6

Synthesis of Compound (12). A procedure similar to that used for compound (4) was used to synthesize (12), which resulted in the production of a white solid.

¹ HNMR (300 MHz, CDCh): d 7.65 (d, 2H, J= 16 Hz, R-CH = CH-R), 7.11-7.03 (m, 6H, Ar-H), 6.41 (d, 2H, J= 16 Hz, R-CH = CH-R), 4.20 (t, 4H, J= 6 Hz), 3.86 (s, 6H, OMe), 2.67 (t, 4H, J= 5.4 Hz), 1.33-1.25 (m, 40H), 0.88 (t, 6H, J= 6.3 Hz, CH ₃ ).

Synthesis of Compound (13). A procedure similar to that used for compound (4) was used to synthesize (13), which resulted in the production of a white solid.

¹ HNMR (300 MHz, CDCh): d 7.65 (d, 2H, J= 16 Hz, R-CH = CH-R), 7.11-7.03 (m, 6H, Ar-H), 6.41 (d, 2H, J= 16 Hz, R-CH = CH-R), 4.20 (t, 4H, J= 6 Hz), 3.86 (s, 6H, OMe), 2.67 (t, 4H, J= 5.4 Hz), 1.33-1.25 (m, 56H), 0.88 (t, 6H, J= 6.3 Hz, CH ₃ ).

Synthesis of Compound (6) ( i.e FA + Ox diacid). Compound (6) was produced as described in Faig et al., Macromol. Chem. Phys., 217(1): 108-114 (2016). T _d = 185 °C

Synthesis of Compound (14) ( i.e CsCio). In a 100 mL round-bottom-flask, 450 mg FA+ox diacid (6), 610 mg 2-octyl -l-dodecanol and 584 mg 4-(dimethylamino)pyridinium 4- toluenesulfonate (DPTS) were dissolved in 20 mL anhydrous methylene dichloride. 2 mL DCC solution (1M, in methylene dichloride) was added dropwisely. After being stirred at room temperature for 24 hours, the reaction was kept in a freezer for 3 hours for byproduct

precipitation. After filtration, the solvent of filtrate was removed in vacuo. Crude product was purified on silica gel via flash chromatography using 4: 1 hexane/ethyl acetate as eluent. The product was obtained as a colorless oil.

C ₈ Cio ¹ HNMR (300 MHz, CDCb): d 7.62 (d, 2H, J= 16 Hz, R-CH = CH-R), 1 09-6.90 (m, 6H, Ar-H), 6.32 (d, 2H, J= 16 Hz, R-CH = CH-R), 4.11 (d, 4H, J= 5.7 Hz), 3.93 (s, 6H,

OMe), 1.33-1.20 (m, 66H), 0.88 (t, 12H, J= 6.3 Hz, CH ₃ ).

Synthesis of Compound (15) ( i.e C10C12). A procedure similar to that used for compound (14) was used to synthesize C10C12 (15), which resulted in the production of a white solid.

¹ HNMR (300 MHz, CDCb): d 7.65 (d, 2H, J= 16 Hz, R-CH = CH-R), 7.11-7.03 (m, 6H, Ar-H), 6.41 (d, 2H, J= 16 Hz, R-CH = CH-R), 4.12 (d, 4H, J= 5.7 Hz), 3.86 (s, 6H, OMe), 2.67 (t, 4H, J= 5.4 Hz), 1.33-1.26 (m, 84H), 0.88 (t, 12H, J= 6.3 Hz, CH ₃ ). EXAMPLE 11

Synthesis of Compound (9) ( i.e SA + adipoyl diacid). Compound (9) was produced as described in Prudencio et al., Macromolecules , 38(l6):6895-690l (2005). T _d = 169 °C.

EXAMPLE 12

Synthesis of Compound (16) ( i.e C2C4). In a 100 mL round-bottom-flask, 350 mg SA+adipoyl diacid (9), 240 mg 2-ethylhexan-l-ol and 584 mg 4-(dimethylamino)pyridinium 4- toluenesulfonate (DPTS) were dissolved in 20 mL anhydrous methylene dichloride. 2 mL DCC solution (1M, in methylene dichloride) was added dropwisely. After being stirred at room temperature for 24 hours, the reaction was kept in a freezer for 3 hours for byproduct precipitation. After filtration, the solvent of filtrate was removed in vacuo. Crude product was purified on silica gel via flash chromatography using 4: 1 hexane/ethyl acetate as eluent. The product was obtained as a colorless oil.

¹ HNMR (300 MHz, CDCb): d 7.85 (d, 2H, J= 7.9 Hz), 7.46 (t, 2H, J= 8.1 Hz), 7.00 (d, 2H, J= 8.1 Hz), 6.89 (t, 2H, J= 8.1 Hz), 4.27 (d, 4H, J= 5.7 Hz), 1.79 (m, 4H), 1.45-1.25 (m, 22H), 0.88 (t, 12H, j= 6.3 Hz, CH ₃ ).

EXAMPLE 13

Synthesis of Compound (17) ( i.e GiCe). A procedure similar to that used for compound (16) was used to synthesize GiCe (17), which resulted in the production of a colorless oil.

¹ HNMR (300 MHz, CDCh): d 7.85 (d, 2H, J= 7.9 Hz), 7.46 (t, 2H, J= 8.1 Hz), 7.00 (d, 2H, J= 8.1 Hz), 6.89 (t, 2H, J= 8.1 Hz), 4.27 (d, 4H, J= 5.7 Hz), 1.79 (m, 4H), 1.45-1.25 (m,

38H), 0.88 (t, 12H, J= 6.3 Hz, CH ₃ ).

EXAMPLE 14

Synthesis of Compound (18) ( i.e CeCs). A procedure similar to that used for compound (16) was used to synthesize CeCs (18), which resulted in the production of a colorless oil.

1HNMR (300 MHz, CDCh): d 7.85 (d, 2H, J= 7.9 Hz), 7.46 (t, 2H, J= 8.1 Hz), 7.00 (d,

2H, J= 8.1 Hz), 6.89 (t, 2H, J= 8.1 Hz), 4.27 (d, 4H, J= 5.7 Hz), 1.79 (m, 4H), 1.45-1.25 (m, 54H), 0.88 (t, 12H, J= 6.3 Hz, CH ₃ ).

EXAMPLE 15

Synthesis of Compound (19) ( i.e CsCio). A procedure similar to that used for compound (16) was used to synthesize CsCio (19), which resulted in the production of a colorless oil.

¹ HNMR (300 MHz, CDCh): d 7.85 (d, 2H, J= 7.9 Hz), 7.46 (t, 2H, J= 8.1 Hz), 7.00 (d, 2H, J= 8.1 Hz), 6.89 (t, 2H, J= 8.1 Hz), 4.27 (d, 4H, J= 5.7 Hz), 1.79 (m, 4H), 1.45-1.25 (m,

7 OH), 0.88 (t, 12H, J= 6.3 Hz, CH ₃ ).

EXAMPLE 16

Synthesis of Compound (20) ( i.e C10C12). A procedure similar to that used for compound (16) was used to synthesize C10C12 (20), which resulted in the production of a colorless oil.

¹ HNMR (300 MHz, CDCb): d 7.85 (d, 2H, J= 7.9 Hz), 7.46 (t, 2H, J= 8.1 Hz), 7.00 (d, 2H, J= 8.1 Hz), 6.89 (t, 2H, J= 8.1 Hz), 4.27 (d, 4H, J= 5.7 Hz), 1.79 (m, 4H), 1.45-1.25 (m, 86H), 0.88 (t, 12H, J= 6.3 Hz, CH ₃ ).

The thermal and solubility properties of a compound described herein may be evaluated using techniques which are well known in the art, e.g., using techniques described in Example 17.

EXAMPLE 17

As described below, the solubility and thermal stability for representative compounds of the invention were evaluated.

The thermal stability of the three diacid intermediates was investigated by

thermogravimetric analysis (TGA) (compounds (3), (6) and (9)). As shown in Figure 2, the FA+adipoly diacid (3) exhibited the highest thermal decomposition temperature (T _d ) of 239 °C in air. Tinder the same conditions, the T _d of FA+ox diacid (6) and SA+adipoyl (9) was 185 °C and 169 °C, respectively. To enhance the oil solubility of the diacids, branched or unbranched alkyl chains of varying length were conjugated via Steglich esterification, thereby generating diesters of formula (I). After incorporating the branched or unbranched alkyl chains, most of the formed esters were a colorless oil, which was in contrast with the powder solid diacids. This change indicated the intermolecular interactions in the diesters were reduced from the strong hydrogen bonding present in the diacid molecules; these reduced interactions facilicate dissolution of the antioxidants in non-polar enviroments. However, the C10C12 esters formed white wax, owing to the stronger interaction between hydrocarbon chains. Solubility

The solubility of certain diesters was investigated and most were shown to be soluble in common solvents, such as hexane, THF, DCM and acetone (Table 2). Solubility in PA04 was also tested by mixing 0.75 wt.% in PAO in the presence of 0.75 wt.% of an alkylated diphenylamine commercial antioxidant using magnetic stirring and up to l20°C heating temperature (Table 2).

Table 2. Solubility of materials in hexane, DCM and PAO 4

Thermal properties

The thermal properties of certain diesters was explored. C8C10 (4) exhibited excellent thermal stability with a T _d above 300 °C (318 °C in air and 322 °C under argon) (Figure 3). Compared with FA+adipoly diacid (3), the conjugation of the alkyl chain did not enhance the thermal stability of C10C12 (5). The T _d of C10C12 (5) was 236 °C in air and 227 °C under Argon.

Formulation Testing

Lubricant compositions, comprising diesters of formula I, were tested as indicated below. The test lubricant compositions were subjected to a stream of air, which is bubbled through the composition at a rate of 5 liters per hour at 325°F for 40 hours or 120 hours. Present in the composition are metals commonly used as materials of engine construction, namely: a) 15.6 sq. in. of sand-blasted iron wire; b) 0.78 sq. in. of polished copper wire; c) 0.87 sq. in. of polished aluminum wire; and d) 0.167 sq. in. of polished lead surface (US Patent 3,682,980). Sample oxidation protection performance is rated on the basis of prevention of oil deterioration, as measured by the increase in the kinematic viscosity (KV) occasioned by the oxidation.

All samples were tested at 0.75 wt.% in PA04 and in presence of an alkylated diphenylamine antioxidant, also at 0.75 wt.% treat rate. A commercial phenolic antioxidant, 6- methylheptyl 3-(3,5-ditertbutyl-4-hydroxyphenyl) propanoate (commercially available from BAST as Irganox L135), was also used as reference at 0.75wt.%. One sample, C8C10 ferulic adipic diester (4) was tested under the 2 oxidation test conditions and compared to the reference.

The samples were tested using more severe conditions: 325°F and 120 hours.

Table 3. Comparison of various formulations

All publications cited herein are incorporated herein by reference. While in this application certain embodiments of invention have been described, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that certain of the details described herein may be varied without departing from the basic principles of the invention.

The use of the terms“a” and“an” and“the” and similar terms in the context of describing embodiments of invention are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms

“comprising,”“having,”“including,” and“containing” are to be construed as open-ended terms (z.e., meaning“including, but not limited to”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. In addition to the order detailed herein, the methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language ( e.g .,“such as”) provided herein, is intended merely to better illuminate embodiments of invention and does not pose a limitation on the scope of the invention unless otherwise specifically recited in the claims. No language in the specification should be construed as indicating that any non-claimed element as essential to the practice of the invention.