INTRODUCTION TO THE INVENTION

The present invention describes compositions and fuel additives which are useful in both gasoline and diesel fuel. The compositions are particularly useful in cleaning valves in gasoline engines and in diesel fuels for preventing color formation.

U.S. Patent 4,670,021, issued June 2, 1987 to Nelson et al describes Michael and Knoevenagel condensation products which are stated to be useful for preventing corrosion in a motor fuel. U.S. Patent 4,490,155, issued December 25, 1984 to Kaufman describes the Mannich reac¬ tion of dia inopropanes with formaldehyde and salicylic acid as carburetor detergents and corrosion inhibitors particularly in gasoline.

Garth in U.S. Patent 4,038,043, issued July 26, 1977 describes the combination of monoa ine and polyamine Mannich condensation products as being useful in gasoline as a carburetor detergent. Similar disclosures to the preceding Garth patent are found in. Garth, U.S. Patent 4,038,044, issued July 26, 1977.

Dorer in U.S. Patent 4,071,327, issued January 31,

1978 discloses salts of amines prepared by the Mannich reaction between a hydroxy-substituted aromatic compound

such as an alkylphenol containing at least 6 carbon atoms, formaldehyde (or a polymer thereof) and a hydroxyalkylsubstituted a ine such as die hanola ine. U.S. Patent 4,456,454, issued June 26, 1984 to Jenkins describes the Mannich reaction product obtained by reacting malonic acid, formaldehyde and an amine or a polyamine. The compositions of Jenkins are stated to be useful in motor vehicle fuel compositions to prevent corrosion and fouling. The present invention as previously noted deals with maintaining clean valves, and in preventing color forma¬ tion in diesel fuels. The dual benefits obtained herein and the flexibility of allowing one additive to function in both gasoline and diesel fuels is desirable. Throughout the specification and claims, percentages and ratios are by weight, temperatures are degrees Celsius and pressures are in KPa gauge unless otherwise indicated. The ranges given herein are exemplary and may be combined. To the extent that the references cited herein are appli- cable to the present invention they are herein incorporat¬ ed in their entirety by reference.

SUMMARY OF THE INVENTION The present invention describes a composition of the formula:

(R) _z N(H) _χ [CH ₂ C(R ¹ ) (R ² )N0 ₂ ] _χ or

0 ₂ N(R ¹ ) (R ² )CCH ₂ N(R)CH ₂ N(R)CH ₂ C(R ¹ ) (R ² )N0 ₂ II

wherein R is at least one hydrocarbyl radical; R 1 and R2 are independently hydrogen or an aliphatic group; x is 0 or 1; y is 1 or 2; and z is 1 or 2; provided further that when R 1 and R2 are both alkyl that R contains more than 5 carbon atoms; and that the sum of x, y and z is 3.

A further aspect of the present invention is a composition of the formula:

RNH[CH ₂ C(CH ₃ ) ₂ N0 ₂ ] III or

RN[CH ₂ C(CH ₃ ) ₂ N0 ₂ ] ₂ IV

wherein the above formulas III and IV, R is a mono-unsatu- rated group of about 2 to about 20 carbon atoms. Com¬ pounds III and IV are species of I and II. A further aspect of the present invention is a diesel fuel composition containing (A) a major amount of a diesel fuel and, (B) a minor amount of

(R) _z N(H) _χ [CH ₂ C(R ¹ ) (R ² )N0 ₂ ] _y I or 0 ₂ N(R ¹ ) (R ² )CCH ₂ N(R)CH ₂ N(R)CH ₂ C(R ¹ ) (R ² )N0 ₂ II

wherein R is a hydrocarbyl radical; R 1 and R2 are indepen¬ dently H or an aliphatic group; x is 0 or 1; y is 1 or 2; z is 1 or 2; and the sum of x, y and z is 3.

A still further feature of the present invention is a gasoline composition comprising a major amount of (C) gasoline and (B) a minor amount of a composition of the formula:

(R) _z N(H) _χ [CH ₂ C(R ¹ ) (R ² )N0 ₂ ] _y I or 0 ₂ N(R ¹ ) (R ² )CCH ₂ N(R)CH ₂ N(R)CH ₂ C(R ¹ ) (R ² )N0 ₂ II

wherein R is a hydrocarbyl radical; R 1 and R2 are inde- pendently hydrogen or an aliphatic group; x is 0 or 1; y is 1 or 2; z is 1 or 2; and the sum of x, y and z is 3. The compositions of the present invention may also be utilized in a method of reducing valve deposits in en¬ gines, injector deposits in engines, or for reducing the color formation in a fuel composition comprising including in the composition an effective amount of:

(R) _z N(H) _χ [CH ₂ C(R ¹ ) (R ² )N0 ₂ ] _y I or

O^fR ¹ ) (R ² )CCH ₂ N(R)CH ₂ N(R)CH ₂ C(R ¹ ) (R ² )N0 ₂ II

wherein R is a hydrocarbyl radical; R 1 and R2 are inde¬ pendently hydrogen or. an aliphatic group; x is 0 or 1; y is 1 or 2; z is 1 or 2; and the sum of x, y and z is 3.

DETAILED DESCRIPTION OF THE INVENTION

This invention as previously stated is useful in both diesel and gasoline fuel compositions. In diesel fuel compositions the invention prevents undesired color formation and assists in cleaning valves. In gasoline composition the present invention is useful in cleaning valves. It is desirable that a single component be useful in both fuels to allow the refiner to store a single additive which may be added as needed to a diesel or gasoline fuel.

In the case of diesel fuels color formation indicates degradation of the fuel leading to a loss of cetane rating. Moreover, if the color formation in the diesel fuel becomes pronounced it is possible to mask the color of the fuel and thus the possibility of cross contamina¬ tion of fuels is possible. That is, various fuels are dyed to prevent the use of the incorrect fuel in the wrong application. For instance, the consequences are quite severe if a diesel fuel is accidentally introduced into a piston-driven aircraft engine.

The compositions of the present invention are useful in gasoline fueled engines to clean the carburetor and intake valves. Fuel injector tips become fouled in diesel or gasoline engines due to hot soak conditions. That is, residual fuel left on or near the injector tip reacts and begins to plug the orifice. If the carburetor, an in¬ jector tip or an intake valve becomes too dirty, the end result is that the engine will not run smoothly.

As previously described the compositions of the present invention have the structure as shown in the Summary where R is at least one hydrocarbyl group.

The R groups are usually purely hydrocarbyl groups, preferably groups such as alkyl or alkenyl radicals. However, the R groups can contain a small number of substituents such as phenyl, cycloalkyl (e.g. , cyclohexyl, cyclopentyl, etc.) and nonhydrocarbon groups such as nitro, amino, halo (e.g., chloro, bromo, etc.) lower

alkoxy, lower alkyl mercapto, oxo substituents (i.e., =0), thio groups (i.e., =S) , interrupting groups such as -NH-, -0-, -S-, and the like provided the essentially hydro¬ carbon character of the R group is retained. The hydro- carbon character is retained for purposes of this inven¬ tion so long as any non-carbon atoms present in the R group do not account for more than about 10% of the total weight of the R groups.

Examples of R groups include ethyl, propyl, butyl, isobutyl, pentyl, octyl, nonyl, dodecyl, docosyl, tetra- contyl, 5-chlorohexyl, 4-ethoxypentyl, 2-hexenyl, cyclo- hexyloctyl, 4-(p-chlσrophenyl)-octyl, 2,3,5-trimethyl- heptyl, 2-ethyl-5-methyloctyl, and substituents derived from polymerized olefins such as polychloroprenes,. poly- ethylenes, polypropylenes, polyisobutylenes, ethylene- propylene copolymers, chlorinated olefin polymers, oxi¬ dized ethylene-propylene copolymers, and the like. Aro¬ matic groups (Ar) may also contain non-hydrocarbon substi¬ tuents, for example, such diverse substituents as lower alkoxy, lower alkyl mercapto, nitro, halo, alkyl or alke¬ nyl groups of less than four carbon atoms, hydroxy, mer¬ capto and the like.

Typically, the hydrocarbyl group R is a material containing more than 5 carbon atoms when R ₁ and R_, as later described, are both alkyl groups.

The value of z is variable in the molecule and may be 1 or 2 such that the amine nitrogen atom in the molecule will be mono- or di-substituted with R. More specifical¬ ly, R will typically contain from 2 to 100 carbon atoms. Often, R is an alkyl or alkenyl group of 2 to about 20 carbon atoms. The group R may also be an alkenyl group of about 4 to about 20 carbon atoms. It is further desired that the group R be a mono-hydrocarbyl substituted.

Oleyl amine is typically a raw material source utilized in obtaining the compositions of the present invention. In such a case, oleyl amine would be repre¬ sented by the formula RNH« such that z is 1 as shown in

formula I in the Summary.

A preferred variable for R are compounds where (R) N- is:

R ³ NHCH ₂ CH ₂ (N-)CH ₂ CH ₂ OH V or

R ³ (N-)CH ₂ CH ₂ NHCH ₂ CH ₂ OH VI or R ³ (N-)CH ₂ CH ₂ CH ₂ NM. VII

₃ In this instance, R is a further hydrocarbyl group which will typically be within the foregoing description of such hydrocarbyl groups. NM is a morpholine residue wherein the two non-oxygen bonded methylene groups are bonded to the nitrogen shown in VII above. The foregoing materials may be obtained as the reaction products of a hydrocarbyl halide, such as the chloride and the amine, e.g.

R ³ C1 + H ₂ NCH ₂ CH ₂ CH ₂ NM.

A further preferred variable for the hydrocarbyl group R is a hydrocarbyl-phenyl group. Typically such materials are alkyl-phenyl. Such groups for example cor¬ respond to nonyl phenyl or dodecyl phenyl. Yet a further

3 variable of R is a group of the formula R OCH ₂ CH ₂ CH ₂ wherein R is a hydrocarbyl group as previously defined.

The source of such materials as previously described

3 include the reaction products of alkyl alcohols (R OH) and a nitrile, such as acrylonitrile, with the resulting product being subsequently reduced to the amine.

As noted above the number of amine hydrogens in the molecule (I) shown in the Summary will be 0 or 1 depending on whether a secondary or tertiary, amine structure is de¬ sired. Thus x has the value of 0 or 1. Correspondingly, the value of y in the formula shown in the Summary will be 1 or 2 depending upon the number of amine hydrogens which

are displaced in the formation of the compounds. Of. course, the sum of x plus y plus z is 3. Moreover, if y is 2 then z must be 1. Further, if z is 2 then y must 1. In one preferred embodiment of the present invention x and y are each 1 and therefore z is 1. In a further embodi¬ ment of the present invention y is 2 and z is 1. The groups R 1 and R2 are independently hydrogen or aliphatic group. Typically, the groups R 1 and R2 will both be aliphatic, preferably alkyl. It is further preferred where R 1 and R2 are both alkyl that ^' R contains at least 5, and preferably 6 carbon" atoms. It is further preferred that R 1 and R2 both be lower alkyl groups.

Lower alkyl groups are typically those containing 6 or less carbon atoms. In particular, it is preferred that R 2 and R be selected from methyl, ethyl, n-propyl, isopro- pyl, n-butyl and 2-methyl propyl. A particularly pre¬ ferred composition is one where R is a mono-unsaturated group of about 2 to about 20 carbon atoms and R 1 and R2 are both methyl groups. This particular molecule may contain a single hydrogen atom or may be di-substituted with the nitro containing moiety.

The compositions shown in the Summary of the Inven¬ tion may also be utilized as mixtures, such as a compound containing a single amine hydrogen in mixture with a composition containing no amine hydrogens. In particular, it is preferred that the aforedescribed mixtures may be obtained by varying the reactants to obtain such mixtures. Of course, if a di-hydrocarbyl substituted amine is used to prepare the compositions it is only possible to obtain the mono-nitro substituted product. However, in this instance if it is desired, a di-hydrocarbyl substituted amine may be utilized in a mixture with a mono-hydrocarbyl substituted amine (e.g., a primary amine) thereby obtain¬ ing a mixture of the composition described in the Summary. The compositions as described in the Summary are typically obtained from an amine corresponding to the formula (R) N(H) wherein z is 1 or 2, and x is 1 or

2 , and the sum of z and x is 3. The amine component is reacted with formaldehyde via the Mannich reaction in the presence of a nitro compound. The preferred nitro compound for use herein is 2-nitroρropane. Other mate- rials which may be used herein as the nitro group include nitromethane, nitroethane, 1-nitropropane, and other nitro parafins that contain at least one hydrogen on the carbon to which the nitro group is attached.

As a suggested method of preparing the compositions shown in the Summary it is possible to use the amine in combination with the nitro compound and formaldehyde typically in an equivalent ratio to obtain the desired product. It is of course also possible to utilize an excess of any of the components. A further possibilty when reacting a primary amine with excess formaldehyde and the nitro compound is to cross-link the nitrogen atoms of the starting primary amine with 1 mole of formaldehyde. Excess formaldehyde is then available for the Mannich product to adduct the nitro groups onto one or both of the remaining hydrogens. The foregoing reaction requires an excess of formaldehyde to allow for the cross-linking of the primary amine groups. Thus when the foregoing product is desired the reaction will utilize 2 moles of a primary amine such as oleyl amine, at least 3 moles of formaldehyde (typically as paraformaldehyde) , and a slight excess e.g., at least 2 moles of the nitro compound typically 2-nitropropane. Thus it can be seen when a primary amine is employed the Mannich reaction competes with the adduction of the nitro groups into the molecule. For instance, where a primary amine is employed and an excess of the nitro compound is utilized the reaction product will typically correspond to one in which y is equal to 2. Of course the foregoing is premised upon the fact that there is suffi- cient formaldehyde to allow complete adduction of the nitro groups through the Mannich reaction such that both primary amine hydrogens are displaced.

However, where an excess of formaldehyde is employed the primary amine will typically be cross-linked and then a further Mannich reaction results in adduction of two of the nitro groups through the remaining hydrogen. Of course, where the two primary amine groups are cross- linked via second Mannich reaction a single methylene group will be present in the molecule.

The typical reaction conditions for combining an amine, an aldehyde and the nitro compound are to conduct the reaction between 50 and 150°C with stirring. Typical¬ ly, the reaction may proceed at any point from the lowest temperature which the reaction takes place up to but not including the decomposition temperature of the component which decomposes first. As water is evolved in the reac- tion, it is desirable that the reaction conditions facili¬ tate the removal of water to promote the reaction. Typi¬ cally, the reaction may be conducted at such a temperature that the water is effectively removed by evaporation. However, at lower temperatures or where the water is desired to be removed rapidly, it is possible to apply a vacuum to facilitate water removal.

The reaction time to obtain the desired products is typically from 1 to 12 hours, preferably from 2 to 5 hours. The following are examples of preparing the composi¬ tions of the present invention.

EXAMPLE A The following components are mixed in a reaction vessel of suitable size. The reactants are oleyl amine (2 moles) ; 2 moles of 2-nitropropane; and 3 moles of paraformaldehyde) .

The reactants are mixed with nitrogen gas bubbled through the reaction mixture as it is heated to reflux. The reaction proceeds exothermically over a period of 4 hours with water being collected in a trap. Evolved 2-ni¬ tropropane is returned to the reaction vessel. The reac¬ tion proceeds as measured by the water volume collected divided by theory to 93% completion. The product is then

filtered and recovered as a methylene linked amine con¬ taining 2 moles of the nitro group adducted through the Mannich reaction to the remaining amine hydrogens.

EXAMPLE B A primary amine containing an oxygen functionality in the hydrocarbyl backbone is obtained as Surfam PA-17B. The Surfam PA-17B has the structural formula n-C ₁₃ H ₂ _OCH ₂ CH ₂ CH ₂ H ₂ . The Surfam product is reacted with the 2-nitropropane and paraformaldehyde in a respective molar ratio of 1:2:1.

The reactants are mixed in a suitable reaction vessel with stirring. The reactants are heated to 100°C and azeotrope of water and 2-nitropropane is evolved. The reaction is continued until the theory water is evolved. The excess nitropropane is stripped off using a slight vacuum and is recovered. The product obtained is yellow in color and fluid. The product is filtered. An infrared analysis of the product shows very little hydroxyl content and a nitro peak at 1530 cm ^"" . The product obtained in this example has the struc- tural formula n-C ₁₃ OCH ₂ CH Ϊ ₂₂ CCHH ₂₂ NNHHCCHH ₂₂ (C(CH..) ₂ N0 ₂ . EXAMPLE C

One mole of Surfam PA-17B, 3 moles of 2-nitropropane, and 2 moles of paraformaldehyde are reacted with stirring and heating at 100°C. A water and nitropropane azeotrope is evolved. The theory water is collected and the reaction is discontinued after approximately 3 hours.

The structure of the compound obtained is ^n"C 13 ^H 27 ^OCH 2 ^CH 2 ^CH 2 ^N[CH 2 ^C(CH 3 ⁾ 2 ^N0 2 ^] 2 ^* EXAMPLE D

A compound of the structure RNHCH ₂ CH ₂ CH ₂ N[CH ₂ CH ₂ ] 0 is reacted with 2-nitropropane and formaldehyde. In the foregoing structure the symbol N[CH ₂ CH_] ₂ 0 indicates a morpholine residue. The previously described morpholine derivative is reacted with the nitropropane and the formaldehyde in a

1:2:1 molar ratio. The reactants are combined in a

suitable reaction vessel and heated to 120°C (reflux) . During this reaction very little water is evolved. After 6 hours the 2-nitropropane reflux ceased. The product is allowed to sit overnight and is then stripped for 30 minutes at 70-100°C using a slight vacuum. Infrared analysis shows a moderate but sharp peak at 1530 cm ^"" indicating the presence of a nitro group. The product is filtered and recovered.

The product obtained has the structural formula given above in this example with the exception that the amine hydrogen is displaced by the group -CH«C(CH,) ₂ 0 ₂ .

The nitro-containing compositions obtained herein are useful in either gasoline or diesel fuel compositions. The fuel compositions for the present invention typi¬ cally comprise a major amount of a liquid hydrocarbon fuel and (B) a minor amount of the nitro containing compounds of the present invention. The present invention is par¬ ticularly relevant to fuel compositions based on gasoline. Gasoline is a mixture of low boiling hydrocarbons typical¬ ly containing from 5 to 10 carbon atoms and which are substantially saturated. Gasoline is more particularly described in the American Society for Testing and Materi¬ als specification ASTM D 439 (Revised 1986) .

The gasolines which may be treated to effect valve and carburetor cleanliness may be leaded, low-lead or unleaded fuels. The term unleaded is used to indicate that no lead compounds such as tetraethyl lead or tetramethyl lead have been intentionally added to the fuel. The term low-lead indicates the fuel contains less than about 0.5 gram of lead per gallon of fuel. The present invention is particularly useful for low-lead fuel compositions containing as little as 0.1 gram of lead per gallon (0.0 to 0.026g/liter) of fuel.

The method of adding the nitro compounds of the present invention to gasoline (or the later described diesel fuel) are by neat addition or through the use of a fluidizer oil. Typically, the fluidizer oil may be any hydrocarbon based fluid and in particular a heavy mineral oil. Thus concentrates of the nitro compound may be obtained typically using one part of the nitro compound per 25-75 parts, preferably 30-70 parts of the fluidizer oil. The end gasoline compositions of the present inven¬ tion will conveniently contain the nitro compounds (B) described in the Summary at 3000 ppm to 1 pp .

DIESEL FUEL A diesel fuel is defined by the American Standards for Testing and Materials in ASTM Specification D 975 (Revised 1981) . Typically, a diesel fuel contains

hydrocarbons having from 10 to 15 carbon atoms. The diesel fuel materials are typically saturated. The amount of the nitro compound utilized in the diesel fuel for color control is typically at a level of 3000 ppm to 1 ppm. More preferably, the use of the nitro compound (B) is in a diesel fuel at 1500 ppm to 100 ppm. Diesel fuels may contain as added ingredients cetane improvers, anti- oxidants and the like.

METHOD OF USE The compounds of the present invention as previously described are conveniently mixed with a fluidizer oil for gasoline engines, and in the case of a diesel fuel, the fluidizer may be omitted in whole or in part and the diesel fuel may be utilized as a concentrate for the nitro compound (B) .

In any event, injection nozzle and valve deposits are diminished and color reduction is effected by adding the nitro compound (B) to the fuel. The manner of addition is typically performed at a refinery, however the nitro compound may be added by a jobber, the fuel pumping station or directly by the ultimate consumer. It is not necessary that the treatment be used on a continual basis as an intermittent usage of the product at the described levels will aid in valve cleanliness. However, when pre- venting color formation in a diesel fuel it is desirable that the entire volume of the fuel be treated to prevent the undesired color formation. When intermittent use is desired for valve cleanliness or injection cleanliness it is suggested that at least every other fill-up of the vehicle tank contain the recommended dosage of the nitro compound (B) .

The following are suggested are exemplifications of the use of the nitro compounds of the present invention.

EXAMPLE I A gasoline composition according to ASTM D-439 is prepared utilizing 200 ppm of the composition of Example A in the gasoline. The product is tested by measuring the cleaning effect of the composition of this Example against an untreated fuel in a similar vehicle. The test is per¬ formed according to the procedure described in SAE Paper 872117 (1987) . The gasoline formulated according to the invention results in greater intake valve and injector tip cleanliness when compared to ^' untreated fuel.

Substantially similar results are obtained through the use of the nitro compounds obtained in Examples B, C and D. EXAMPLE II

A diesel fuel is obtained as defined in ASTM D-975 (1981) . The diesel fuel has added thereto 300 ppm of the additive of Example B. The product is tested for retard¬ ing color formation by placing a 50ml sample of the filtered fuel in a 3 x 20cm pyrex test tube. The color of the fuel is then initially determined by ASTM D-1500. The samples including a blank are then heated to 149°C (300°F) in an oil bath for 90 minutes. The color is determined for each sample tested. _o The composition containing the additive of Example B is superior to the sample containing no additive in retarding color formation.

Substantially similar results are obtained through the use of the compounds obtained in Examples A, C and D in place of the nitro compound of Example B as shown above.