PROCESSES SUITABLE FOR PRODUCING MACROMOLECULAR ANTIOXIDANT COMPOSITIONS

FIELD OF THE INVENTION

[0001] This invention relates to processes for the production of reaction mixtures having oxidation inhibition characteristics.

BACKGROUND OF THE INVENTION

[0002] It is well known that a wide variety of organic materials are susceptible to oxidative degradation in the presence of air or oxygen, especially when at elevated temperatures. Such organic materials include, for example, gasolines, diesel fuels, burner fuels, gas turbine and jet fuels, automatic transmission fluids, gear oils, engine lubricating oils, thermoplastic polymers, natural and synthetic rubber, and the like. Over the years, considerable efforts have been devoted to discovery and development of compounds capable of minimizing the degradation of one or more of such materials. As conditions of use and exposure of such materials to various oxygen containing environments change over the years, the desire for new effective macromolecular oxidation inhibitors (a.k.a. antioxidants) continues. Also, the art benefits greatly if new and highly effective process technology is provided for producing known effective macromolecular oxidation inhibitors.

[0003] U.S. Pat. No. 3,673,091 discloses forming oxidation inhibitors by the reaction between

3,5-di-tert-butyl-4-hydroxybenzyl alcohol and aryl amines, carbazole, phenazines, or acridines.

Unfortunately, the resultant reaction product is a complex mixture of products in which the desired product is formed in low yields and work-up procedures are complex and relatively ineffective.

SUMMARY OF THE INVENTION

[0004] This invention provides new process technology for producing a wide variety of macromolecular oxidation inhibitors, including novel groups of macromolecular oxidation inhibitors having superior properties. In at least some cases, this new process technology has been found to readily produce desired products in essentially quantitative yields, thus simplifying, if not eliminating, the need for use of purification procedures which can be time consuming and costly. This invention also provides novel compositions in which macromolecular oxidation inhibitors producible by process technology of this invention can be effectively utilized to provide effective inhibition of oxidative degradation of materials normally susceptible to oxidative degradation, including exposure to high temperatures during use.

[0005] Accordingly, pursuant to one of the aspects of this invention, there is provided process

technology for producing a wide variety of macromolecular oxidation inhibitors which possess superior properties enhancing their use as oxidation inhibitors for use in various materials. More particularly, one embodiment of such process technology is a process for preparing macromolecular antioxidant products, which process comprises bringing together to form a reaction mixture, components comprising:

(A) a sterically hindered 4-hydroxymethyl-2,6-dihydrocarbylphenol, preferably a sterically hindered 4-hydroxymethyl-2,6-dialkylphenol, and more preferably a 4-hydroxymethyl-2,6-di-tert- butylphenol and;

(B) (1 ) at least one aromatic amine having in the range of 1 to about 4 aromatic rings in the molecule which rings are in the form of fused rings or singly bonded rings, or both, and having at least one primary amino group (-NH ₂ ), secondary amino group (-NHR where R is a hydrocarbyl group containing up to about 18 carbon atoms), or tertiary amino group (NR ₂ where each R is independently a hydrocarbyl group containing up to about 18 carbon atoms), and preferably at least one such primary or secondary amino group, or

(2) at least one heterocyclic compound which is a monocyclic or polycyclic compound wherein:

(a) if the heterocyclic compound is monocyclic, the monocyclic group of the monocyclic compound is fully conjugated and has as the sole heteroatom(s) in the fully conjugated ring thereof (i) one nitrogen atom, one sulfur atom, or one oxygen atom, (ii) one sulfur and one nitrogen atom, one sulfur and one oxygen atom, or one nitrogen and one oxygen atom, or (iii) two nitrogen atoms, two sulfur atoms, or two oxygen atoms, and

(b) if the heterocyclic compound is polycyclic, at least one of the cyclic groups of the polycyclic compound is fully conjugated and has as the sole heteroatom(s) in the fully conjugated ring thereof (i) one nitrogen atom, one sulfur atom, or one oxygen atom, (ii) one sulfur and one nitrogen atom, one sulfur and one oxygen atom, or one nitrogen and one oxygen atom, or (iii) two nitrogen atoms, or two sulfur atoms, or two oxygen atoms;

(C) an alkylation catalyst, and

(D) optionally, an organic solvent,

such that said at least one aromatic amine or heterocyclic compound is alkylated to form a reaction product mixture between at least one component of (A) and at least one component of (B), with co-formation of water.

[0006] Various relative proportions of (A) and (B) can he used, whereby there is a molar excess of (A) relative to (B). In preferred embodiments, (A) and (B) are used in a molar ratio of (A) to (B) in the range of about 3:1 to about 10:1, more preferably 3:1 to about 7:1. [0007] In some embodiments, (B) is (B)(I), and (B)(I) is one or more alkylated diphenylamines or diphenyl amine.

[0008] In some embodiments, a molar excess of (B) can be used. It should be noted that in these embodiments, the molar excess of (B) can suitably act as a solvent. Thus, in preferred embodiments, when a molar excess of (B) is used as a solvent in the processes of the present invention, the optional organic solvent is not employed. Further, in these embodiments, it is preferred that (B) be selected from (B)(2). DETAILED DESCRIPTION OF THE INVENTION Processes of the Invention

[0009] It has now been discovered that various aromatic amines or heterocyclic compounds and 4-hydroxymethyl-2,6-dihydrocarbylphenol can react under appropriate reaction conditions whereby at least one replaceable hydrogen atom on a ring of the aromatic amine or heterocyclic compound is alkylated such that the hydrogen atom is replaced by a 2,6-dihydrocarbyl-4- hydroxybenzyl group, and water is formed as a co-product. The appropriate reaction conditions include having a liquid phase and an alkylation catalyst, preferably an acidic alkylation catalyst, in the reaction mixture. In most cases, reaction initiates on bringing the components together even at room temperature. Initially, the reaction is exothermic.

[0010] In the practice of the present invention, (A) a sterically hindered 4-hydroxymethyl-2,6- dihydrocarbylphenol, is combined with (B) at least one aromatic amine or at least one heterocyclic compound; (C) an alkylation catalyst, optionally (D) an organic solvent, thus forming a reaction product that is suitable as, among other things, an antioxidant. Component (A)

[0011] The sterically hindered 4-hydroxym ethyl -2,6-dihydrocarbylphenol, used as a reactant in the processes of this invention can be any of a relatively large group of compounds. The

hydrocarbyl groups in the ortho positions relative to the carbon atom carrying the hydroxyl group can be any univalent hydrocarbon group with the proviso that the resultant substitution in the 2- and 6- positions provides steric hindrance to the hydroxyl group. Typically, a total of at least 4 or 5 carbon atoms in the ortho positions is required to achieve steric hindrance. Among suitable hydrocarbyl groups that can be in the ortho positions are alkyl, cycloalkyl, alkenyl, cycloalkenyl, cycloalkylalkyl, aryl, and aralkyl in which the cyclic moieties, whether saturated or unsaturated, can in turn be alkyl substituted. The alkyl and alkenyl groups can be linear or branched. The individual hydrocarbyl groups in the ortho positions can each contain in the range of 1 to about 12 carbon atoms with the total number of carbon atoms in the ortho positions being in the range of about 4 to about 18 carbon atoms and preferably in the range of 8 to about 16 carbon atoms. 4-hydroxymethylphenols in which at least one of the ortho positions is substituted by a tertiary alkyl group are preferred. Component (B)(I)

[0012] In the practice of the present invention, a broad range of aromatic amines are contemplated for use in the present invention. The aryl groups can have one, two or more rings, e.g. , they can be phenyl, naphthyl, etc. , and can be substituted or unsubstituted. Each aryl group can have in the range of 6 to 36 or more carbon atoms depending upon the nature and degree of substitution although generally they will have from 6 to about 18 carbon atoms. Substituted diphenylamines wherein at least one of the rings is substituted by a branched chain alkyl group having in the range of 3 to about 24 and preferably in the range of 4 to about 12 carbon atoms illustrate substitution of this type.

[0013] Non-limiting examples of suitable aromatic amines include diphenylamine, one or a mixture of nonylated diphenylamines prepared from, for example, propylene trimer and diphenylamine, one or a mixture of octylated diphenylamines prepared from diisobutylene and diphenylamine, one or a mixture of butylated diphenylamines prepared from isobutylene and diphenylamine, one or a mixture of styrenated diphenylamines prepared from styrene and diphenylamine, phenyl-α-naphthylamine, one or a mixture of nonylated phenyl-α-naphthylamines prepared from propylene trimer and phenyl-α-naphthylamine, one or a mixture of octylated phenyl-α-naphthylamines prepared from diisobutylene and phenyl-α-naphthylamine, one or a mixture of butylated phenyl-α-naphthylamines prepared from isobutylene and phenyl-α-

naphthylamine, one or a mixture of styrenated phenyl-α-naphthylamines prepared from styrene and phenyl-α-naphthylamine, ortho-phenylenediamine, para-phenylenediamine, N,N-di-sec- butyl-p-phenylenediamine, aniline, N-methylaniline, N,N-dimethylaniline, toluidine, N-methyl-o- toluidine, N-methyl-p-toluidine, N,N-dimethyl-o-toluidine, N,N-dimethyl-p-toluidine, 2,6- diethylaniline, 2-ethyl-6-methylaniline, 2,6-diisopropylaniline, o-tert-butylaniline, triphenylamine, 2-4'-diaminobiphenyl, 4,4'-diaminobiphenyl, 1 -naphthylamine, 2-naphthylamine, N-m ethyl- 1 -naphthylamine, N,N-dimethyl-l -naphthylamine, 2-aminobiphenyl, 3-aminobiphenyl, 4-amino-4'-methylbiphenyl and similar alkyl substituted or unsubstituted monoamines or polyamines, and mixtures of any two or more of the foregoing. In some embodiments, (B) is (B)(I), and (B)(I) is diphenylamine, and in other embodiments, (B)(I) is one or more alkylated diphenylamines. Component (B)(2)

[0014] In some embodiments, (B) is (B2), and (B)(2) can be any of a number of compounds such as those described above. In the practice of the present invention, (B)(2) is typically selected from heterocyclic compounds which are monocyclic or polycyclic compounds wherein the monocyclic group or at least one of the cyclic groups of the polycyclic compound is fully conjugated and has as the sole heteroatom(s), (i) one nitrogen atom, or one sulfur atom, or one oxygen atom, (ii) one sulfur and one nitrogen atom, one sulfur and one oxygen atom, one nitrogen and one oxygen atom, or (iii) two nitrogen atoms, or two sulfur atoms, or two oxygen atoms in the fully conjugated ring. Non-limiting examples of such compounds include pyrrole, imidazole, pyrazole, pyridine, pyrimidine, pyrazine, phenazine, thiophene, 2-benzothiophene, dibenzothiophene, dithiine, benzodithiine, indole, quinoline, acridine, carbazole, oxazole, isoxazole, thiazole, and isothiazole, furan, 2-benzofuran, 1,4-dioxin, benzodioxin, dibenzodioxin, and dibenzofuran. The rings of such compounds can be substituted by one or more electron releasing groups such as hydroxy, mercapto, alkoxy, amino, monoalkylamino, dialkylamino, and/or hydrocarbyl groups provided that at least one replaceable activated hydrogen atom remains on the ring. Non-limiting examples of such substituted compounds include 2- methylpyrrole, 2-ethylpyrrole, 2-methylpyridine, 2,4-dimethylpyridine, 2,3-dimethylpyrazine, 2- ethylpyridine, 2-methylimidazole, 2-methylfuran, 2-ethylfuran, 2,3-dimethylfuran and similar alkylated (e.g., C _1-I2 ) heterocyclic compounds of the types referred to above.

Component (C)

[0015] In the practice of the present invention, an alkylation catalyst is used to promote the reaction between (A) and (B), thus the reaction between (A) and (B) is sometimes referred to as an akylation reaction herein. The alkylation reaction catalyst used herein can be selected from any alkylation catalyst known to promote the reaction of (A) and (B). In some embodiments, (C) is preferably an acidic catalyst such as sulfuric acid, an aryl sulfonic acid, an alkyl sulfonic acid, or an aryl alkyl sulfonic acid. Non-limiting examples of other suitable alkylation catalysts include, for example, hydrochloric acid, hydrobromic acid, aluminum chloride, diethyl aluminum chloride, triethylaluminum/hydrogen chloride, ferric chloride, zinc chloride, antimony trichloride, stannic chloride, boron trifluoride, acidic zeolites, acidic clays, and polymeric sulfonic acids such as those sold under the name Amberlyst®. Component (D)

[0016] The processes are carried out in a liquid reaction medium that can result from one of the reactants being a liquid under the conditions of the alkylation reaction, or which can result from use of an inert organic solvent. Non-limiting examples of organic solvents which can be used include, for example, acetic acid, propionic acid, one or more hexane isomers, one or more heptane isomers, one or more octane isomers, one or more decanes, mixtures of one or more of the alkane solvents such as the foregoing, cyclohexane, methylcyclohexane, methylene dichloride, methylene dibromide, bromochlorom ethane, 1,2-dichloroethane, 1,2-dibromoethane, chloroform, chlorobenzene, mixtures of one or more chlorinated and/or brominated solvents such as the foregoing, and one or a mixture of alkanols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, 2- ethylhexyl alcohol, octyl alcohol, and other liquid or low melting homologous alkanols, and one or more ethers like dialkyl ethers, tetrahydrofuran, dioxane or mixtures thereof. In some embodiments, the solvent is a hydrocarbon solvent. In preferred embodiments, (D) is used in the practice of the present invention. Processes of the Present Invention

[0017] The processes of the present invention are conducted at one or more temperatures in the range of from about 2O ⁰ C to about 160 ⁰ C or higher. In some embodiments, the processes of the present invention are conducted at one or more temperatures above 40 ⁰ C, preferably in the range

of from 7O ⁰ C to about 16O ⁰ C, or higher. The inventors hereof have discovered that reaction temperatures within these ranges are more suitable for producing the reaction products of the present invention. Further, the inventors hereof have discovered that at higher temperatures, i.e. greater than 4O ⁰ C, the processes of the present invention proceed more rapidly and thus completion can be reached in shorter periods of time than previously contemplated. [0018] With lower boiling reactants and/or solvents the reaction may be conducted under pressure, or the reaction may be conducted in the presence of a cooling condenser. In most cases, the reaction results in alkylation on an activated, electron rich ring. In some cases, alkylation may occur on a nitrogen atom.

[0019] In the practice of the present invention, the inventors hereof have discovered that by varying the relative molar ratio of (A) to (B), one can produce various macromolecular reaction products, as described below, that find use as antioxidants. In some embodiments, (A) and (B) are used in a molar ratio of (B) to (A) in the range of from about 1 : 1 to about 1 :10, preferably in the range of from about 1 : 1 to about 1 :7; in some embodiments, in the range of from about 1 :3 to about 1: 10, preferably in the range of from about 1 :3 to about 1 :7. In preferred embodiments, the molar ratio of (B) to (A) can be any of about 1:1, about 1:2, about 1:2.5, about 1 :3, about 1:3.5, about 1:4, about 1 :4.5, about 1 :5, about 1:5.5, about 1:6, about 1 :6.5, or about 1:7. [0020] It will be appreciated by one having ordinary skill in the art that when (B) is (B)(I), the products of the present invention have one or more, preferably two or more, more preferably all of the following properties:

1. substantially free of unreacted aromatic amine starting material

2. substantially free of the phenolic starting material

3. substantially free of mono-alkylated aromatic amines

4. have very low levels of di-alkylated aromatic amines, by very low it is meant within the ranges described below

5. are rich in poly-substituted aromatic amines, by rich it is meant within the ranges described below

6. contain alkylated methyl ene-bridged amine phenolic macromolecules.

[0021] In preferred embodiments, if the reaction products of the present invention are described as having one of 1-6, it is 6.

[0022] The macromolecular antioxidant compositions of the present invention can also be described as liquid or low melting amorphous solids with high solubility in engine oils, as described below. Also of significance is the discovery that a 2,6-dihydrocarbyl-4- hydroxmethylphenol such as 2,6-di-tert-butyl-4-hyroxymethylphenol can be reacted with branched chain alkyl -substituted aromatic amines and branched chain substituted carbazole, phenazine, acridine, thiophene, pyrrole, and furan to provide antioxidants having higher solubility in common organic solvents than products referred to in the patent. Products of the Invention

[0023] As noted above, the macromolecular reaction products produced by the processes of the present invention are useful as antioxidants; thus, these macromolecular reaction products are sometimes referred to herein as alkylated aromatic amines or alkylated heterocyclic compounds, antioxidant products, macromolecular antioxidant compositions, or macromolecular oxidation inhibitors for simplicity. As stated above, preferred antioxidant products of the present invention are compounds that are liquid at room temperatures (about 23°C) or solids that melt at less than about 100 ⁰ C, preferably about 6O ⁰ C, and that are capable of being dissolved in common organic solvents and especially in liquid hydrocarbon solvents. In addition, in many cases these products have higher solubility in lubricants such as, for example, a base oil consisting of 50% by volume of high viscosity index 100 Neutral and 50% by volume of high viscosity index 250 Neutral such as referred to in U.S. Pat. No. 3,673,091.

[0024] When (B) is (B)(I), the antioxidant products produced by the processes of the present invention typically comprise one or more alkylated aromatic amines, and one or more alkylated aromatic amines having a methylene bridged. The alkylated aromatic amines typically comprise one or more i) aromatic amines substituted with one 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, sometimes referred to herein as mono-alkylated aromatic amines; ii) aromatic amines substituted with two 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, sometimes referred to herein as di-alkylated aromatic amines; iii) aromatic amines substituted with three 3,5-di-hydrocarbyl-4- hydroxylbenzyl groups, sometimes referred to herein as tri-alkylated aromatic amines; iv) aromatic amines substituted with four 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, sometimes referred to herein as tetra-alkylated aromatic amines; v) aromatic amines substituted with five 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, sometimes referred to herein as penta-alkylated

aromatic amines; vi) aromatic amines substituted with six 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, sometimes referred to herein as hexa-alkylated aromatic amines; and vii) one or more methylene-bridged aromatic amines substituted with one or more 3,5-di-hydrocarbyl-4- hydroxylbenzyl groups. It is preferred that the processes of the present invention be operated in such a manner that the reaction products produced therefrom contain less than about 5wt.% of aromatic amines substituted with one 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, based on the total weight of the reaction product; 10wt.% or less of aromatic amines substituted with two 3,5- di-hydrocarbyl-4-hydroxylbenzyl groups; or 5wt.% or less of aromatic amines substituted with one 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups and aromatic amines substituted with two 3,5- di-hydrocarbyl-4-hydroxylbenzyl groups, on the same basis. In some embodiments, the antioxidant products produced by the present invention comprise greater than 40wt.% aromatic amines substituted with four 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, aromatic amines substituted with five 3,5-di-hydrocarbyl-4-hydroxylbenzyI groups, or aromatic amines substituted with six 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, all based on the total weight of the antioxidant product. In the above embodiments, the antioxidant products produced by the present invention contain in the range of from about 1 to about 20wt.%, of one or more methylene- bridged aromatic amines substituted with one or more 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, all based on the total weight of the antioxidant product.

[0025] In some embodiments, the antioxidant products of the present invention can be described as comprising i) less than about 5wt.%; preferably less than about lwt.%, more preferably less than about 0.5wt.%, aromatic amines substituted with one 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, all based on the total weight of the antioxidant product; ii) less than about 10wt.%; preferably less than about 5wt.%, more preferably less than about lwt.%, aromatic amines substituted with two 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, all based on the total weight of the antioxidant product; iii) in the range of from about 1 wt.% to about 35 wt.%, preferably in the range of from about 5wt.% to about 25 wt.%, more preferably in the range of from about 5wt% to about 20wt.% aromatic amines substituted with three 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, on the same basis; iv) in the range of from about 10wt% to about 65 wt.%, preferably in the range of from about 15wt% to about 60wt.%, more preferably in the range of from about 20wt% to about 55wt.% aromatic amines substituted with four 3,5-di-hydrocarbyl-4-

hydroxylbenzyl groups, on the same basis; v) in the range of from about 5wt% to about 60wt.%, preferably in the range of from about 8wt% to about 50wt.%, more preferably in the range of from about 10wt% to about 40wt.% aromatic amines substituted with five 3,5-di-hydrocarbyl-4- hydroxylbenzyl groups, on the same basis; vi) in the range of from about lwt% to about 50 wt.%, preferably in the range of from about 5wt% to about 35wt.%, more preferably in the range of from about 5wt% to about 20wt.% aromatic amines substituted with six 3,5-di-hydrocarbyl-4- hydroxylbenzyl groups, on the same basis; and vii) in the range of from about 1 to about 20 wt.%, preferably in the range of from about 1 to about 15wt.%, more preferably in the range of from about 1 wt% to about 10wt.% of one or more methylene-bridged aromatic amines substituted with one or more 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups.

[0026] The antioxidant products produced by the present invention also contain in the range of from about 1 to about 10 wt.% of one or more phenolics represented by the following general formula:

wherein each R and R' are independently H or a hydrocarbyl. In preferred embodiments, R and R' are H or a straight or branched chain, preferably branched chain, alkyl group. In a particularly preferred embodiment R and R' are tert-butyl and the compound is 4,4'- methylenebis(2,6-di-tert-butylphenol):

[0027] In some embodiments, the reaction products produced by the present invention comprise one or more compounds that can be represented by the following general formula, Formula I:

wherein Ri is H or hydrocarbyl, R ₂ is H or hydrocarbyl, R ₃ & R ₄ are 3,5-dihydrocarbyl-4- hydroxybenzyl, R ₅ and R ₆ are H or hydrocarbyl, n is a whole number in the range of from about 0 to about 1, p and q are whole numbers and p+q is in the range of from about 1 to about 10, and m is 1 when n=0 and m is a whole number in the range of from about 2 to about 10 when n=l . It should be noted that in some embodiments, the macromolecular antioxidant compositions of the present invention contain more than one molecule represented by the above-described general formula. In these embodiments, each of the one or more compounds can have the same or different constituents for Ri, R ₂ , R3, R _4, R ₅ , and R ₆ and each of the one or more compounds can have the same or different values for p, q, m, and n.

[0028] In some embodiments, the macromolecular antioxidant compositions produced by the present invention contain one or more, preferably two or more, compounds represented by the following general formulas:

Formula II:

wherein Ri, R ₂ , R ₅ , and R^ of Formula II are independently H or hydrocarbyl, R & R' are independently hydrogen or a branched or straight chain alkyl containing in the range of from about 1 to about 8 carbons, preferably in the range of from about 1 to about 4 carbon atoms, and p and q are independently whole numbers in the range of from about 1 to about 10, wherein p+q is about 10. It should be noted that if the macromolecular antioxidant compositions of the present invention contain more than one compound of Formula II, each of the compounds can have the

same or different constituents for Ri, R ₂ R5, and Re, R and R', and each of the one or more compounds can have the same or different values for p and q; and Formula III:

wherein Ri ₁ R ₂ , R ₅ , Re, R _? R', are the same as described above, and p and q are whole numbers and p+q is in the range of from about 1 to about 12. It should be noted that if the macromolecular antioxidant compositions of the present invention contain more than one compound of Formula III, each of the compounds can have the same or different constituents for Ri, R ₂ , R ₅ , and R ₆ , R and R', and each of the one or more compounds can have the same or different values for p and q.

[0029] It is also obvious to the skilled in the art that the substitution pattern shown in Formulas I, II, and III is for visual representation only and the alkyl and phenolic substitutions may take place on all the available active sites on the amine molecule.

[0030] Some non-limiting examples of specific compounds represented by the above-described formulas are:

[0031] The antioxidant products produced by this invention, such as those described above, preferably have boiling points at atmospheric pressure of at least about 175 ⁰ C. The number or average number of 2,6-dihydrocarbyl-4-hydroxybenzyl groups in the products of this invention can vary depending upon the number of replaceable hydrogen atoms on the electron rich aromatic

ring. For example, in the case of diphenylamine substituted only on one ring by a single branched chain alkyl group containing in the range of 3 to about 24 carbon atoms, the number of unsubstituted positions is nine while the number of activated positions in most cases is actually five, and thus the number of 2,6-dihydrocarbyl-4-hydroxybenzyl groups on the diphenylamine rings of a product of this invention will typically be no greater than five. [0032] In some embodiments, the macromolecular antioxidant products produced by the present invention can be, and preferably are, characterized as having one or more, preferably two or more, more preferably all of the following properties:

1. substantially free of unreacted aromatic amine starting material

2. substantially free of the phenolic starting material

3. substantially free of aromatic amines substituted with one 3,5-di-hydrocarbyl-4- hydroxylbenzyl groups

4. have very low levels of aromatic amines substituted with two 3,5-di-hydrocarbyl-4- hydroxylbenzyl groups, by very low it is meant within the ranges described above

5. are rich in poly-substituted aromatic amines, by rich it is meant within the ranges described above

6. contain alkylated methylene -bridged amine phenolic macromolecules.

[0033] When (B) is (B)(2), the antioxidant products of the present invention typically comprise one or more alkylated heterocyclic compounds, and one or more alkylated heterocyclic compound having a methylene bridge. In these embodiments, the antioxidant products produced by the present invention typically comprise one or more heterocyclic compounds substituted with one or more 3,5-di-hydrocarbyl-4-hydroxylbenzyl group(s), and one or more heterocyclic compounds substituted with one or more 3,5-di-hydrocarbyl-4-hydroxylbenzyl group(s) and having a methylene bridge. The alkylated heterocyclic compound typically comprise one or more i) heterocyclic compounds substituted with one 3,5-di-hydrocarbyl-4-hydroxylbenzyl group; ii) heterocyclic compounds substituted with two 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups; iii) heterocyclic compounds substituted with three 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups; iv) heterocyclic compounds substituted with four 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups; v) heterocyclic compounds substituted with five 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups; and vi) one or more methylene-bridged heterocyclic compounds substituted with one or more, in

some embodiments in the range of from about 1 to about 12, 3,5-di-hydrocarbyl-4- hydroxylbenzyl groups. In these embodiments, it is preferred that the macromolecular reaction products produced by the present invention contain less than about 10 wt.% of heterocyclic compounds substituted with one 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, based on the total weight of the reaction product; 25 wt.% or less of heterocyclic compounds substituted with two 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, on the same basis; or 25 wt.% or less of heterocyclic compounds substituted with one 3,5-di-hydrocarbyl-4-hydroxylbenzyl group and heterocyclic compounds substituted with two 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, on the same basis, In some embodiments, the antioxidant products produced by the present invention comprise greater than 15 wt.%, heterocyclic compounds substituted with three 3,5-di- hydrocarbyl-4-hydroxylbenzyl groups, in other embodiments, greater than about 40 wt.%, of heterocyclic compounds substituted with four 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups and heterocyclic compounds substituted with five 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, all based on the total weight of the antioxidant product. In the above embodiments, the antioxidant products of the present invention contain in the range of from about 1 to about 20wt.% of one or more methylene-bridged heterocyclic compounds substituted with one or more 3,5-di- hydrocarbyl-4-hydroxylbenzyl groups, all based on the total weight of the antioxidant product. [0034] In some embodiments, the antioxidant products produced by the present invention can be described as comprising i) less than about 10 wt.%; preferably less than about 5 wt.%, more preferably less than about 1 wt.%, heterocyclic compounds substituted with one 3,5-di- hydrocarbyl-4-hydroxylbenzyl groups, all based on the total weight of the antioxidant product; ii) less than about 20 wt.%; preferably less than about 15 wt.%, more preferably less than about 10 wt.%, heterocyclic compounds substituted with two 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, all based on the total weight of the antioxidant product; iii) in the range of from about 15 wt.% to about 40 wt.%, preferably in the range of from about 15 wt.% to about 30 wt.%, more preferably in the range of from about 10 wt% to about 20wt.% heterocyclic compounds substituted with three 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, on the same basis; iv) in the range of from about 10wt% to about 70 wt.%, preferably in the range of from about 15wt% to about 65 wt.%, more preferably in the range of from about 20wt% to about 60 wt.% heterocyclic compounds substituted with four 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, on the same basis; v) in the

range of from about 5wt% to about 45 wt.%, preferably in the range of from about 8wt% to about 40 wt.%, more preferably in the range of from about 10wt% to about 35wt.% heterocyclic compounds substituted with five 3,5-di-hydrocarbyl-4-hydroxylbenzyl groups, on the same basis; and vi) in the range of from about 1 wt% to about 15wt.%, preferably in the range of from about 1 to about 10wt.% of one or more methylene-bridged heterocyclic compounds substituted with one or more, in some embodiments in the range of from about 1 to about 12, 3,5-di-hydrocarbyl-4- hydroxylbenzyl groups., all based on the total weight of the antioxidant product. [0035] In some embodiments, the reaction products comprise one or more compounds represented generally by Formula IV:

wherein X is sulfur, oxygen, or nitrogen, R ₂ is H or hydrocarbyl, R ₃ is 3,5-dihydrocarbyl- 4-hydroxybenzyl, Ri is H or hydrocarbyl, n is a whole number in the range of from about 0 to about 1, p is a whole number in the range of from about 1 to about 10, and m is 1 when n=0 and m is a whole number in the range of from about 2 to about 10 when n= 1. In some embodiments, Rl is H, n=0, m=l , and p=l and the reaction products of the present invention can be represented by Formula V:

[0036] In some embodiments, X is sulfur, in some embodiments, X is oxygen, and in other embodiments, X is nitrogen.

[0037] As can be readily understood when discussing the degree of alkylation of the heterocyclic compounds in the reaction products of the present invention, the inventors hereof are referring to

the "p" value. For example, if the reaction product is represented by the Formula I, a mono- alkylated heterocyclic compound would have a "p" value of 1 and be represented generally by Formula VI,

[0038] In Formula III, R and R' are independently H or hydrocarbyl, and Rl and X are as described above.

[0039] In some embodiments, the macromolecular antioxidant compositions of the present invention contain one or more, preferably two or more, compounds represented by the following general Formula VII:

wherein R, R', Rl, R2 and R4 are independently hydrogen or hydrocarbyl, q and s are whole numbers and q+s=p, and X is as described above. For example, a tetra-alkylated methylene- bridged compound represented by Formula VII may be represented by Formula VII:

[0040] It is also obvious to the skilled in the art that the substitution pattern shown in Formulas

V, VI, VIl, and VIII is for visual representation only and the alkyl and phenolic substitutions may take place on all the available active sites on the heterocyclic molecule.

[0041] The reaction products produced by this invention, find use as antioxidants in a variety of materials that are susceptible to oxidative degradation in the presence of air or oxygen.

[0042] The above description is directed to several embodiments of the present invention. Those skilled in the art will recognize that other means, which are equally effective, could be devised for carrying out the spirit of this invention. It should also be noted that preferred embodiments of the present invention contemplate that all ranges discussed herein include ranges from any lower amount to any higher amount.

[0043] The following examples will illustrate the present invention, but are not meant to be limiting in any manner.

EXAMPLES _.

COMPARATIVE EXAMPLE 1

[0044] The process described in US Pat. No.3,673,091 was repeated. The product was analyzed by LC -Mass and contained 35% unreacted diphenylamine, 43% mono-substituted, 16% disubstituted, and 2% tri-substituted product with less than 1 % of higher substituted isomers. The components of the antioxidant product thus produced, and their amounts, are illustrated in the Table, below. COMPARATIVE EXAMPLE 2

[0045] The process described in LJS Pat. No. 3,673,091 was repeated with a diphenylamine and 2,6-di-tert-butyl-4-hydroxybenzylalcohol mole ratio of 1 :4. The isolated product contained 20% mono-substituted, 36% di-substituted, 21% tri-substituted, 3% tetra-substituted, less than 0.5% penta-substituted, less than 0.1% hexa-substituted isomers and no methylene-bridged oligomers. The components of the antioxidant product thus produced, and their amounts, are illustrated in the Table, below.

EXAMPLE 3: Diphenylamine and 2,6-di-tert-butyl-4-hydroxyben∑yl alcohol mole ratio of 1:4 [0046] A three-necked round-bottomed flask was equipped with an addition funnel, magnetic stirrer, temperature probe, and a condenser. Diphenylamine (0.025 mol, 4.2g) was dissolved in dichloromenthane (40 niL) and sulfuric acid (3.6 mL of 80%) was added at room temperature. A solution of 2,6-di-tert-butyl-4-hydroxybenzyl alcohol (0.1 mol, 23.6 g) in dichloromethane (100

niL) was added at 4O ⁰ C and in small increments. An exothermic reaction ensued during the addition of the first equivalent of 2,6-di-tert-butyl-4-hyroxymethylphenol, but it subsided when the addition continued. The addition of the 2,6-di-tert-butyl-4-hyroxymethylphenol was completed in 1 hr. The reaction mixture was stirred at 40 ⁰ C overnight. The acid phase was separated and the organic phase was washed with water(2x 50 mL), dilute sodium hydroxide to a pH of 7-8, and water(lx 30 mL) and dried over magnesium sulfate. Evaporation of solvent under water aspirator pressure afforded bright yellow/orange solid. Analysis by NMR and LC -Mass showed mono-substituted isomer (<0.5%), di-substituted isomer (4%), tri-substituted isomer (21%), tetra-substituted isomer (53%), penta-substituted isomer (18%), hexa-substituted isomer (<0.5%). In addition 2% of methylene-bridged and oligomeric compounds were identified in the sample.

EXAMPLE 4: Diphenylamine and2,6-di-tert-butyl-4-hydroxybenzyl alcohol mole ratio of 1:5 [0047] A three-necked round-bottomed flask was equipped with an addition funnel, magnetic stirrer, temperature probe, and a condenser. Diphenylamine (0.0125 mol, 2.1 g) was dissolved in dichloromenthane (40 mL) and sulfuric acid (2.5 mL of 80%) was added at room temperature. A solution of 2,6-di-tert-butyl-4-hydroxybenzyl alcohol (0.063 mol, 14.9 g) in dichloromethane (100 mL) was added at 40 ⁰ C and in small increments. An exothermic reaction ensued during the addition of the first equivalent of 2,6-di-tert-butyl-4-hyroxymethylphenol, but it subsided when the addition continued. The addition of the 2,6-di-tert-butyl-4-hyroxymethylphenol was completed in 1.5 hrs. The reaction mixture was stirred at 40 ⁰ C for four hours. The acid phase was separated and the organic phase was washed with water(2x 50 mL), dilute sodium hydroxide to a pH of 7-8, and water(lx 30 mL) and dried over magnesium sulfate. Evaporation of solvent under water aspirator pressure afforded bright yellow/orange solid. Analysis by NMR and LC- Mass showed mono-substituted isomer (<0.5%), di-substituted isomer (<0.5%), tri-substituted isomer (2%), tetra-substituted isomer (20%), penta-substituted isomer (47%), hexa-substituted isomer (20%). In addition 8% of methylene-bridged and oligomeric compounds were identified in the sample.

EXAMPLE 5: Diphenylamine and 2,6-di-tert-butyl-4-hydroxybenzyl alcohol mole ratio of 1:7 [0048] A three-necked round-bottomed flask was equipped with an addition funnel, magnetic

stirrer, temperature probe, and a condenser. Diphenylamine (0.0125 mol, 2.1 g) was dissolved in dichloromenthane (40 mL) and sulfuric acid (2.5 niL of 80%) was added at room temperature. A solution of 2,6-di-tert-butyl-4-hydroxybenzyl alcohol (0.875 mol, 21 g) in dichloromethane (120 mL) was added at 40 ⁰ C and in small increments. An exothermic reaction ensued during the addition of the first equivalent of 2,6-di-tert-butyl-4-hyroxymethylphenol, but it subsided when the addition continued. The addition of the 2,6-di-tert-butyl-4-hyroxymethylphenol was completed in about 2 hrs. The reaction mixture was stirred at 40 ⁰ C for 6 hrs. The acid phase was separated and the organic phase was washed with water(2x 50 mL), dilute sodium hydroxide to a pH of 7-8, and water(lx 30 mL) and dried over magnesium sulfate. Evaporation of solvent under water aspirator pressure afforded bright yellow/orange solid. Analysis by NMR and LC- Mass showed mono-substituted isomer (0.5%), di-substituted isomer (<0.5%), tri-substituted isomer (<0.5%), tetra-substituted isomer (3%), penta-substituted isomer (5%), hexa-substituted isomer (49%). In addition 14% of methylene-bridged and 14% oligomeric compounds were identified in the sample. The experimental results of the above examples are summarized in the following Table.

All products identified in the Table contained between 0.1-7.0 wt% of 4,4'-methylenebis(2,6-di- tert-butylphenol).