US3542680A

US3542680A - Oil-soluble carboxylic acid phenol esters and lubricants and fuels containing the same

Info

Publication number: US3542680A
Application number: US866081A
Authority: US
Inventors: William M Le Suer
Original assignee: Lubrizol Corp
Current assignee: Lubrizol Corp
Priority date: 1963-04-23
Filing date: 1969-10-03
Publication date: 1970-11-24
Anticipated expiration: 1987-11-24
Also published as: DE1271877B; US3632510A; US3522179A; GB1055337A; US3579450A

Abstract

Additives for lubricating oils, hydrocarbon oils and power transmitting fluids are oil-soluble esters of hydrocarbon substituted succinic acid, the hydrocarbon being saturated and being a polymer containing at least 50 aliphatic carbon atoms. Examples of the ester are the dimethyl ester of polyisobutene succinic anhydride, the polyisobutene succinic anhydride which has been esterified with polyethylene glycol and further reacted with barium oxide to produce a mixed ester-metal salt and the polyisobutene succinic anhydride which has been esterified with a styrene-allyl alcohol copolymer and then reacted with propylene oxide. Examples are given of the addition of these esters to SAE mineral lubricating oils which may also include the usual additives especially the metal phosphor dithioates and their epoxide adducts.ALSO:The invention comprises an oil-soluble ester of a hydrocarbon-substituted succinic acid, the hydrocarbon being saturated and being a polymer containing at least 50 aliphatic carbon atoms. The ester may be prepared by reacting an alcohol or phenol with a hydrocarbon-substituted succinic anhydride or acid, preferably at 150 DEG to 300 DEG C. and in the presence of an esterification catalyst, by reacting an epoxide or a mixture of an epoxide and water with a hydrocarbon substituted succinic anhydride or acid or acid halide, by reacting maleic acid or anhydride with an alcohol and reacting the obtained mono- or di-ester of maleic acid with the polyolefin, and, finally by esterifying itaconic anhydride or acid and then reacting with the polyolefin. The preferred method is by reacting a polyhydric alcohol having 2-10 OH radicals with 0.5-10 moles of hydrocarbon-substituted succinic anhydride, the hydrocarbon being a polymer of a C2- 6 mono-olefin having a M.Wt. of 700-5000. The examples relate to the treatment of polyisobutene succinic anhydride and of the succinic anhydride of the copolymer of 90 isobutene and 10 piperylene. The esters may be used as lubricant addititives.

Description

United States Patent 3,542,680 OIL-SOLUBLE CARBOXYLIC ACID PHENOL ESTERS AND LUBRICANTS AND FUELS CONTAINING THE SAME William M. Le Suer, Cleveland, Ohio, assignor to The Lubrizol Corporation, Wickliffe, Ohio, a corporation of Ohio No Drawing. Continuation of application Ser. No.

722,152, Apr. 18, 1968, which is a'continuation-inpart of application Ser. No. 567,320, July 22, 1966, which in turn is a continuation of application Ser. N 0. 274,905, Apr. 23, 1963. This application Oct. 3, 1969, Ser. No. 866,081 The portion of the term of the patent subsequent to July 22, 1983, has been disclaimed Int. Cl. Cm 1/26 U.S. Cl. 25257 12 Claims ABSTRACT OF THE DISCLOSURE Esters of high molecular Weight carboxylic acids with hydroxy aromatic compounds such as phenols and naphthols. An exemplary group of esters are the mono esters, diesters, and mixtures thereof prepared from polyisobutenyl-substituted succinic acid or anhydride and monohydroxy or polyhydroxy phenols. The esters are especially useful as additives in fuels and lubricants.

This is a continuation of Ser. No. 722,152 filed Apr. 18, 1968 which is a continuation-in-part application of copending application Ser. No. 567,320 filed July 22, 1966, now U.S. Pat. 3,381,022, which, in turn, is a continuation of abandoned application Ser. No. 274,905, filed Apr. 23, 1963. g

This invention relates to novel compositions of matter and processes for preparing the same. In a more particular sense this invention relates to compositions useful as plasticizers, detergents, anti-rust agents, emulsifiers, and additives in lubricating compositions, fuels, hydrocarbon oils, and power transmitting fluids.

Deterioration of lubricating oils, especially mineral oils, has been a great concern in the formulation of lubricating compositions for use in internal combustion engines, transmissions, gears, etc. Deterioration of the oil results in the formation of products which are corrosive to the metal surfaces with which the oil comes into contact. It also results in the formation of products which agglomerate to form sludgeand varnish-like deposits. The deposits cause sticking of the moving metal parts and obstruct their free movement. They are a principal cause of malfunctioning and premature breakdown of the equipment which the oil lubricates.

It is known that water is a common contaminant in the crankcase lubricant of an engine. It may result from the decomposition of the lubricating oil or come from the combustion chamber as a blow-by product of the burning of the fuel. The presence of water in the lubricant seems to promote the deposition of a mayonnaise-like sludge. This type of sludge is more objectionable because it clings tenaciously to metal surfaces and is not removed by oil filters. If the engine is operated under conditions such that the crankcase lubricant temperature is continuously high the water will be eliminated about as fast as it accumulates and only a very small amount of the mayonnaise-like sludge will be formed. On the other hand, if the crankcase lubricant temperature is intermittently high and low or consistently low the Water will accumulate and a substantial quantity of "ice the mayonnaisedike sludge will be deposited in the engine.

High operating temperatures are characteristic of an engine that is run consistently at a relatively high speed. However, where an automobile is used primarily for trips of short distance such as is characteristic of urban, hometo-Work use, a significant portion of the operation occurs before the engine has reached its optimum high temperature. An ideal environment thus obtains for the accumulation of Water in the lubricant. In this type of operation the problem of mayonnaise-like sludge has been especially troublesome. Its solution has been approached by the use in the lubricant of detergents such as metal phenates and sulfonates which have been known to be effective in reducing deposits in engines operated primarily at high temperatures. Unfortunately, such known detergents have not been particularly effective in solving the problems associated with low temperature operation particularly those problems which are associated with crankcase lubricants in engines operated at low or intermittently high and low temperatures.

It is accordingly a principal object of this invention to provide novel compositions of matter.

It is also an object of this invention to provide compositions which are suitable for use as additives in hydrocarbon oils.

It is also an object of this invention to provide compositions which are effective as additives in lubricating compositions.

It is another object of this invention to provide compositions effective as detergents in lubricating compositions intended for use in engines operated at low or intermittently high and low temperatures.

It is another object of this invention to provide a process of preparing additives useful as additives in hydrocarbon oils and lubricating compositions.

It is another object of this invention to provide lubricating compositions.

It is further an object of this invention to provide fuel compositions.

These and other objects of this invention can be achieved by providing oil-soluble esters of substantially saturated monoor polycarboxylic acids and a hydroxy aromatic compound, said ester being characterized by the presence Within its structure of (A) a carboxylic acid moiety which is an acyl radical of a monoor polycarboxylic acid having at least about fifty aliphatic carbon atoms and (B) an oxy aromatic radical which is an oxy radical of a hydroxy aromatic compound. The lubricant and fuel compositions of the invention are achieved by incorporating at least one of these esters into a lubricant or fuel as explained more fully hereafter.

As will be appreciated by those skilled in the art,

'esters of carboxylic acids and hydroxy aromatic compounds can be represented generically by the formula where R is the residue of the acid group and R is the residue of the hydroxy aromatic compound. As used herein, acyl radical refers to the group 0 ll Bil-C- and oxy aromatic radical refers to O-R Of course, the exact nature of R and R depends on the particular acylating agent and hydroxy aromatic compound employed in making the ester. For example, where an alkenyl-substituted succinic acid acylating agent is employed, the acyl radical can be O alkenyl-OH-QI- alkcnyl-CH-lIi-OH CHz-fi-OH C1124"?- O Similarly, where the oxy aromatic radical is derived from a polyhydric phenol of the formula the oxy radical can be --0 (oH)1 z 0 2% 0H The acyl radical of the esters of this invention is derived from a monoor polycarboxylic acid. One particularly important characteristic of the acyl radical is its size. The radical should contain at least about fifty aliphatic carbon atoms. This limitation is based upon both oil-solubility considerations and the effectiveness of the compositions as additives in lubricants and fuels. Another important aspect of the acyl radical is that it preferably should be substantially saturated, i.e., at least about 95% of the total number of the carbon-to-carbon covalent linkages therein preferably should be saturated linkages. In an especially preferred aspect of the invention, at least about 98% of these covalent linkages are saturated. Obviously, all of the covalent linkages may be saturated. A greater degree of unsaturation renders the esters more susceptible to oxidation, degradation, and polymerization and this lessens the effectiveness of the final products as lubricant and fuel additives.

In addition, the acyl radical of the esters should be substantially free from oil-solubilizing pendant groups, that is, groups having more than about six aliphatic carbon atoms. Although, some such oil-solubilizing pendant groups may be present, they preferably will not exceed one such group for every twenty-five aliphatic carbon atoms in the principal hydrocarbon chain of the acyl radical.

The acyl radical may contain polar substitutents provided that the polar substitutents are not present in proporitons sufficiently large to alter significantly the hydrocarbon character of the radical. Typical suitable polar substituents are halo, such as chloro and bromo, oxo, oxy, formyl, sulfonyl, sulfinyl, thio, nitro, etc. such polar substituents, if present, preferably Will not exceed by weight of the total weight of the hydrocarbon portion of the carboxylic acid radical exclusive of the carboxyl group.

(Zarboxylic acid acylating agents suitable for preparing the esters are Well-known in the art and have been described in detail, for example, in U.S. Pats. 3,087,936; 3,163,603; 3,172,892; 3,189,544; 3,219,666; 3,272,746; 3,288,714; 3,306,907; 3,331,776; 3,340,281; 3,341,542; and 3,346,354. In the interest of brevity, these patents are incorporated herein for their disclosure of suitable monoand polycarboxylic acid acylating agents which 4 can be used for the preparation of the esters used as starting materials in the present invention.

As disclosed in the foregoing patents, there are several processes for preparing the acids. Generally, the process involves the reaction of (1) an ethylenically unsaturated carboxylic acid, acid halide, or anhydride with (2) an ethylenically unsaturated hydrocarbon containing at least about fifty aliphatic carbon atoms or a chlorinated hydrocarbon containing at least about fifty aliphatic carbon atoms at a temperature within the range of about l00300 C. The chlorinated hydrocarbon or ethylenically unsaturated hydrocarbon reactant can, of course, contain polar substitutents, oil-solubilizing pendant groups, and be unsaturated within the general limitations explained hereinabove. It is these hydrocarbon reactants which provides most of the aliphatic carbon atoms present in the acyl moiety of the final products.

When preparing the carboxylic acid acylating agent according to one of these two processes, the carboxylic acid reactant usually corresponds to the formula R (COOH) where R is characterized by the presence of at least one ethylenically unsaturated carbon-tocarbon covalent bond and n is an integer from one to six and preferably one or two. The acidic reactant can also be the corresponding carboxylic acid halide, anhydride, ester, or other equivalent acylating agent and mixtures of one or more of these. Ordinarily, the total number of carbon atoms in the acidic reactant will not exceed ten and generally will not exceed six. Preferably the acidic reactant will have at least one ethylenic linkage in an a,;8-position with respect to at least one carboxyl function. Exemplary acidic reactants are acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhyride, mesaconic acid, glutaconic acid, chloromaleic acid, aconitic acid, crotonic acid, methylcrotonic acid, sorbic acid, 3-hexenoic acid, lO-decenonic acid, and the like. Due to considerations of economy and availability, these acid reactants usually employed are acrylic acid, methacrylic acid, maleic acid, and maleic anhydride.

As is apparent from the foregoing discussion, the carboxylic acid acylating agents may contain cyclic and/or aromatic groups. However, the acids are essentially aliphatic in nature and in most instances, the preferred acid acylating agents are aliphatic monoand polycarboxylic acids, anhydrides, and halides.

The substantially saturated aliphatic hydrocarbonsubstituted succinic acid and anhydrides are especially preferred as acylating agents in the preparation of the esters used as starting materials in the present invention. These succinic acid acylating agents are readily prepared by reacting maleic anhydride with a high molecular weight olefin or a chlorinated hydrocarbon such as a chlorinated polyolefin. The reaction involves merely heating the two reactants at a temperature of about 300 C., preferably, 100200 C. The product from such a reaction is a substituted succinic anhydride where the substituent is derived from the olefin or chlorinated hydrocarbon as described in the above cited patents. The product may be hydrogenated to remove all or a portion of any ethylenically unsaturated covalent linkages by standard hydrogenation procedures, if desired. The substituted succinic anhydrides may be hydrolyzed by treatment with water or steam to the corresponding acid and either the anhydride or the acid may be converted to the corresponding acid halide or ester by reacting with phosphorus halide, phenols, or alcohols.

The ethylenically unsaturated hydrocarbon reactant and the chlorinated hydrocarbon reactant used in the preparation of the acylating agents are principally the high molecular weight, substantially saturated petroleum fractions and substantially saturated olefin polymers and the corresponding chlorinated products. The polymers and chlorinated polymers derived from mono-olefins having from two to about thirty carbon atoms are preferred.

The especially useful polymers are the polymers of 1- mono-olcfins such as ethylene, propene, l-butene, isobutene, l-hexene, l-octene, Z-methyl-l-heptene, 3-cyclohexyl 1 butene, and Z-methyl-S-propyhl-hexene. Polymers of medial olefins, i.e., olefins in which the olefinic linkage is not at the terminal position, likewise are useful. These are exemplified by 2-butene, 3-pentene, and 4- octcne.

The interpolymers of l-mono-olefins such as illustrated above with each other and with other interpolymerizable olefinic substances such as aromatic olefins, cyclic olefins, and polyolefins, are also useful sources of the ethylenically unsaturated reactant. Such interpolymers include for example, those prepared by polymerizing isobutene with styrene, isobutene with butadiene, propane with isoprene, propene with isobutene, ethylene with piperylene, isobutene with chloroprene, isobutene with p-methyl-styrene, l-hexene with 1,3-hexadiene, l-octene with l-hexene, lheptene with l-pentene, 3-methyl-1-butene with l-octene, 3,3-dimethyl-l-pentene with l-hexene, isobutene with styrene and piperylene, etc.

For reasons of oil-solubility and stability, the interpolymers contemplated for use in preparing the acylating agents of this invention should be substantially aliphatic and substantially saturated, that is, they should contain at least about 80% and preferably about 95 on a weight basis, of units derived from aliphatic mono-olefins. Preferably, they will contain no more than about 5% olefinic linkages based on the total number of the carbon-to-carbon covalent linkages present.

The chlorinated hydrocarbons and ethylenically unsaturated hydrocarbons used in the preparation of the acylating agents can have molecular weights of from about 700 up to about 100,000 or even higher. The preferred reactants are the above described polyolefins and chlorinated polyolefins having an average molecular weight of about 700 to about 5,000. When the acylating agent has a molecular weight in excess of about 10,000, the esters also possess viscosity index improving qualities.

In lieu of the high molecular weight hydrocarbons and chlorinated hydrocarbons discussed above, hydrocarbons containing activating polar substituents which are capable of activating the hydrocarbon molecule in respect to reaction with an ethylenically unsaturated acid reactant may be used in the above-illustrated reactions for preparing the acylating agents. Such polar substituents include sulfide and disulfide linkages, and nitro, mercapto, carbonyl, and formyl radicals. Examples of these polar-substituted hydrocarbons include polypropene sulfide, di-polyisobutene disulfide, nitrated mineral oil, di-polyethylene sulfide, brominated polyethylene, etc.

The acylating agents may also be prepared by halogenating a high molecular weight hydrocarbon such as the above described olefin polymers to produce a polyhalogenated product, converting the poly-halogenated product to a poly-nitrile, and then hydrolyzing the polynitrile. They may be prepared by oxidation of a high molecular weight polyhydric alcohol with potassium permanganate, nitric acid, or a similar oxidizing agent. Another method for preparing such poly-carboxylic acids involves the reaction of an olefin or a polar-substituted hydrocarbon such as a chloropolyisobutene with an unsaturated poly-carboxylic acid such as 2-pentene-1,3,5- tricarboxylic acid prepared by dehydration of citric acid. Mono-carboxylic acid acylating agents may be obtained by oxidizing a mono-alcohol with potassium permanganate or by reacting a halogenated high molecular weight olefin polymer with a ketene. Another convenient method for preparing mono-carboxylic acid involves the reaction of metallic sodium with an acetoacetic ester or a malonic ester of an alkanol to form a sodium derivative of the ester and the subsequent reatcion of the sodium derivative with a halogenated high molecular weight hydrocarbon such as brominated wax or brominated polyisobutene.

Mono-carboxylic and poly-carboxylic acid acylating agents can also be obtained by reacting chlorinated monoand poly-carboxylic acids, anhydrides, acyl halides, and the like with ethylenically unsaturated hydrocarbons or ethylenically unsaturated substituted hydrocarbons such as the polyolefins and substituted polyolefins described hereinbefore in the manner described in 3,340,281.

The mono-carboxylic and poly-carboxylic acid anhydrides are obtained by dehydrating the corresponding acids. Dehydration is readily accomplished by heating the acid to a temperature above about C., preferably in the presence of a dehydration agent, e.g. acetic anhydride. Cyclic anhydrides are usually obtained from polycarboxylic acids having acid radicals separated by no more than three carbon atoms such as substituted succinic or glutaric acid, whereas linear anhydrides are obtained from poly-carboxylic acids having the acid radicals separated by four or more carbon atoms.

The acid halides of the mono-carboxylic and polycarboxylic acids can be prepared by the reaction of the acids or their anhydrides with a halogenating agent such as phosphorus tribromide, phosphorus pentachloride, or thionyl chloride.

The esters of this invention are those prepared from acylating agents of the type described above with monohydroxy and polyhydroxy aromatic compounds. The aromatic nucleus of the aromatic compound should be a benzene ring or an aromatic condensed hydrocarbon ring such as naphthalene. Monohydroxy and polyhydroxy phenols and naphthols are preferred hydroxy aromatic compounds. These hydroxy-substituted aromatic compounds may contain other substituents in addition to the hydroxy substitutents such as halo, alkyl, alkenyl, alkoxy, nitro, and the like. Usually, the hydroxy aromatic compound will contain one to four hydroxy groups. The aromatic hydroxy compounds from which the esters of this invention may be derived are illustrated by the following specific examples: phenol, p-chlorophenol, pnitrophenol, beta-naphthol, alpha-naphthol, cresols, resorcinol, catechol, carvacrol, thymol, eugenol, p,p'-dihydroxybiphenyl, hydroquinone, pyrogallol, phloroglucinol, hexylresorcinol, orcin, guaiacol, 2-chlorophenol, 2,4-dibutylphenol, propene tetramer-substituted phenol, didodecylphenol, 4,4 methylene bis phenol, alpha decylbeta naphthol, polyisobutene (molecular weight of 1000)-substituted phenol, the condensation product of heptylphenol with 0.5 mole of formaldehyde, the condensation product of octylphenol with acetone, di(hydroxyphenyl)0xide, di(hydroxyphenyl)sulfide, di(hydroxyphenyl)disulfide, and 4-cyclohexylphenol. Phenol and aliphatic hydrocarbon substituted phenols, e.g., alkylated phenols, having up to three aliphatic hydrocarbon substituents are especially preferred. Each of the aliphatic hydrocarbon substituents may contain or more carbon atoms but usually will have from one to twenty carbon atoms. Alkyl and alkenyl groups are the preferred aliphatic hydrocarbon substituents.

As the esters of the invention can be prepared from monoor polycarboxylic acid acylating agents, the esters may be monoesters, polyesters, or acidic esters. For example, when the ester is prepared from a substituted succinic acid acylating agent, an acidic or monoester can be produced or both carboxyl groups may each react with a hydroxy group to produce a diester. Similarly, when a polyhydric aromatic compound is used in the preparation of the ester, it may be completely esterified or only partially esterified; i.e., it may retain nonesterified free hydroxyl radicals. Mixtures of these various esters are contemplated as being within the scope of this invention.

The esters may be prepared by any of several conventional methods. See, for example, R. D. Olfenhauer, The Direct Esterification of Phenols, Journal of Chemical Education, vol. 41, No. 1, p. 39 (1964), and the references cited therein. A convenient method involves the reaction of a hydroxy aromatic compound with a carboxylic acid or anhydride. The esterification is usually carried out at a temperature above about 100 C., preferably between 150 C. and 300 C.

The water formed as a by-product is removed by distillation as the esterification proceeds. A substantially inert liquid diluent may be used in the esterification to facilitate mixing, temperature control, the removal of water, etc. Any substantially inert organic liquid can be used as a diluent. Suitable diluents include the aliphatic, cycloaliphatic, and aromatic hydrocarbons and their chlorinated analogs exemplified by pentane, hexane, heptane, cyclohexane, benzene, toluene, xylene, chlorobenzene, diphenyl ether, chlorohexane, and the like. Mineral oils, naphthas, ligroin, and the like may also be used as a diluent.

The following illustrates the reaction of a dicarboxylic acid acylating agent (substituted succinic anhydride) and a polyhydric aromatic compound.

It will be readily appreciated that the above equations are only illustrative. Other products not represented by Formulas I, II, and III may be formed. Polymeric esters formed by the condensation of two or more molecules of each of the succinic acid reactant and the polyhydric alcohol reactant likewise may be formed. In most cases involving either a polycarboxylic acid acylating agent or a polyhydric aromatic compound, the product is a mixture of esters, the precise chemical composition and the relative proportions of which are difiicult to determine. Consequently, the products of these reactions are conveniently described in terms of the process by which they are formed.

A modification of the above illustrative process involves the replacement of the substituted succinic anhydride with the corresponding succinic acid. However, succinic acids readily undergo dehydration at temperatures above about 100 C. and are thus converted to their anhydrides which are then esterified by the reaction with the hydroxy aromatic reactant. In this regard, succinic acids appear to be the substantial equivalent of their anhydrides in the process.

Still other methods of preparing the esters of this invention are available. For instance, the esters may be obtained by the reaction of a lower molecular weight acrylating agent, e.g. acrylic acid, methacrylic acid, maleic acid or anhydride, fumaric acid, itaconic acid or anhydride, etc., with a hydroxy aromatic compound to form the corresponding esters and then reacting these esters with an olefin or a chlorinated hydrocarbon as illustrated above. The conditions, catalyst, etc., discussed above can be used in conducting the esterification reaction and in reacting the esters with the olefins and chlorinated olefins.

The relative proportions of the acylating agent and the hydroxy aromatic compound depend in part, upon the type of the product desired and the number of carboxylic acid groups in the acylating agent and hydroxyl groups present in the hydroxy aromatic compound. For instance, the formation of a half ester of a succinic acid, i.e., one in which only one of the two acid radicals is esterified, involves the use of one mole'of phenol for each mole of the substituted succinic acid reactant, whereas the formation of a diester of a succinic acid involves the use of two moles of phenol for each mole of the acid. On the other hand, one mole of a hydroquinone may combine with two moles of a succinic acid to form an ester in which both hydroxyl radicals of hydroquinone are esterified with one of the two acid radicals of the succinic acid. Thus, the maximum amount of acylating agent to be used with a polyhydric aromatic compound is determined by the number of hydroxyl groups present in the molecule of the hydroxy reactant. For the purposes of this invention, it has been found that esters obtained by the reaction of about equi-molar amounts of the acylating agent and hydroxy aromatic compound have superior properties and are therefore preferred. Those esters prepared from the reaction of at least stoichiometrically equivalent amounts of acylating agent and hydroxy aromatic compound, i.e., about one hydroxy group for each carboxylic acylating group present in the reaction mixture, are especially preferred. It is sometimes desirable to employ an excess of the hydroxy aromatic compound in preparing the esters, e.g., about a 5%l00% by weight stoichiometric excess based on the stoichiometric amount required to produce a given desired ester.

In most instances it is advantageous to carry out the esterification in the presence of a catalyst such as sulfuric acid, pyridine hydrochloride, hydrochloric acid, polyphosphoric acid, benzene sulfonic acid, p-toluene sulfonic acid, phosphoric acid, or any other known esterification catalyst. The amount of the catalyst in the reaction may be as little as 0.01% (by weight of the reaction mixture), more often from about 0.1% to about 5%.

Upon completion of the reaction, unreacted hydroxy aromatic compound can be removed, if desired, by conventional techniques. Usually removal is accomplished by distillation at reduced pressure. However, if the hydroxy aromatic compound is oil-soluble, it can be left in the reaction mixture without interfering with the dispersant capabilities of the esters. Moreover, if it is desired that the reaction mixture be substantially free from unreacted carboxyl groups for a particular application, this can be readily accomplished by post-treating the reaction mixture with an epoxide according to applicants copending application Ser. No. 712,606, filed Mar. 13, 1968, now abandoned for continuation Ser. No. 866,081 filed Oct. 3, 1969. This epoxide post-treatment may also result in the reaction of unreacted hydroxy groups with epoxides to form hydroxyalkoxy substituents on the aromatic nucleus. If sufficient epoxide is employed, the aromatic nucleus having the unesterified hydroxy group will react with more than one epoxide. For example, three moles of propylene oxide, ethylene oxide, or a mixture thereof can react to produce a substituent of the formula where R is H or ---CH;.;. The epoxide post-treatment improves the performance of the esters as sludge dispersants.

The following examples illustrate the preparation of esters of the type contemplated by the present invention. Unless otherwise indicated, the terms parts and percent refer to parts by weight and percent by weight, respectively, when used in these examples and elsewhere in the specification and claims.

EXAMPLE 1 The following acylating agents are prepared according to conventional processes as illustrated.

(A) A polyisobutenyl-substituted succinic anhydride is prepared by the reaction of a chlorinated polyisobutylene with maleic anhydride at 200 C. The polyisobutenyl radical has an average molecular weight of about 850 and the resulting alkenyl succinic anhydride is found to have an acid number of 113 (corresponding to an equivalent weight of about 500).

(B) A polyisobutenyl-substituted succinic anhydride having an acid number of 105 and an equivalent weight of 540 is prepared by the reaction of a chlorinated polyisobutylene (having an average molecular weight of 1050 and a chlorine content of 4.3%) and maleic anhydride.

EXAMPLE 2 A mixture comprising 1028 parts of a polyisobutenylsubstituted succinic anhydride (average molecular Weightl028; prepared as in 1(A), 282 parts of phenol, 19 parts of toluene-sulfonic acid mono hydrate, and 514 parts of xylene is heated to reflux (153 C.) and maintained at this temperature for five hours. Thereafter, the mixture is cooled and 19 additional parts of toluenesulfonic acid esterification catalyst is added. Heating at reflux (153 154 C.) is continued for twenty-eight hours. The reaction mixture is then cooled to C. and 7.5 parts of sodium hydroxide dissolved in 24 parts of water is added. The resulting reaction mixture is then stripped at 68 C. at 21 mm. (Hg) and then at 223 C. at 21 mm. (Hg). The stripped product is then dissolved in 756 parts of mineral oil to produce an oil solution of the desired ester product. If desired, this oil solution can be filtered.

Following the general procedure of Example 2, the following acylating agents and hydroxy aromatic compounds are reacted in the equivalent ratios indicated to produce additional ester products of the present invention.

TABLE Example Equivalent N0. Acylatmg agent (A) Hydroxy aromatic compound (B) ratio (AzB) Anhydn'de of 1(B) Alpha-naphthol 1. 1:1 Anhydride of 1(0) 4,4 -methylenc-bis-phenol 2:1

.. Anhydride of 1(D) di(hyd1oxyphenyl)oxide 1. 5:1

Anhydride of 1(E) Propene tetramer-substituted phen 1:1

7 Anhydride oi 1(F) Resorcinol 1:2 8 Acid of 1(G) 4-butylphen0l 1 1. 1 9 Anhydride of 1(H) Alpha-decyl-beta-naphthol 1:1 10 Acid oi 1(1) Resorcinol 1;2

(C) A polypropenyl-substituted succinic anhydride is prepared by the reaction of a chlorinated polypropylene (having a molecular weight of about 900 and a chlorine content of about 4%) and maleic anhydride at 200 C. The product has an acid number of 75.

(D) A substituted succinic anhydride is prepared by treating maleic anhydride with a chlorinated copolymer of isobutylene and styrene. The copolymer consists of 94 parts of isobutylene units and 6 parts of styrene units and has an average molecular Weight of 1200 and a chlorine content of 2.8% by weight. The resulting succinic anhydride has an acid number of 40.

(E) A polypropylene-sirbstituated succinic anhydride having an acid number of 84 is prepared by the reaction of a chlorinated polypropylene having a chlorine content of 3% and a molecular weight of 1200 Wih maleic anhydride.

(F) A substituted succinic anhydride having an acid number of about 54 is prepared by reacting maleic anhydride with a chlorinated (1.95% by weight chlorine) copolymer of isobutylene and isoprene. The copolymer consists of 99 parts by weight of isobutylene units and one part of isoprene units and has an average molecular weight of about 28,000.

(G) A high molecular weight polyisobutenyl-substituted carboxylic acid is prepared by heating an equimolar mixture of a chlorinated polyisobutene having a molecular Weight of 1 000 and a chlorine content of 4.7% and methacrylic acid at 150 C.

(H) A polyisobutene having a molecular weight of 1000 and maleic anhydride heated at 150220 C. to

As mentioned above, it is sometimes desirable to posttreat the esters of this invention with epoxides. The posttreatment enhances the sludge-dispersing capabilities of the products in many environments, e.g., crankcase lubricants, etc.

The organic epoxides used in the post-treatment of the esters can have up to about forty carbon atoms and may be represented by the formula n RD lH-CH 0 where each R is independently hydrogen or an aliphatic, cycloaliphatic, or aromatic radical. Normally R will be hydrogen or an alkyl, haloalkyl, cycloalkyl, halocycloalkyl, aryl, or haloaryl radical having no more than one halogen radical for every three carbon atoms. The lower alkylene and haloalkylene epoxides, including the cycloalkylene epoxides, containing from two to eight carbon atoms are especially preferred for post-treating the esters. The arylene and haloarylene epoxides contemplated are those containing from one to two resonant ring structures such as phenyl, naphthyl, or substituted phenyl and naphthyl such as alkyl phenyl or halophenyl (e.g., tolyl, cresyl, cylyl, methyl naphthyl, chlorophenyl, etc.). Phenyl and halophenyl radicals are the preferred R groups among the aryl epoxides. The epoxides in which at least one of the carbon atoms attached to the oxygen in the oxirane ring is also attached to two hydrogen atoms are especially preferred. Those epoxides are designated as terminal epoxides.

11 Specific examples of the organic epoxides useful in the process of this invention are ethylene oxide, propylene oxide, 1,2-epoxybutane, 1,2-epoxy-3butane, 1,2-epoxypentane, 1,2-epoxyheptane, 1,2-epoxydodecane, 2,3-epoxybutane, 1,2-epoxy-5-hexane,

methyl ester of 9,10-epoxy-stearic acid, and epoxidized fatty acid esters in which the fatty acid radical has up 1 to about thirty aliphatic carbon atoms and the alcohol radical is derived from an aliphatic alcohol having u to about eight carbon atoms. Ethylene oxide, propylene oxide and epichlorohydrin are particularly preferred for posttreating the esters.

The post-treatment process involves contacting the ester or mixture of esters with an epoxide or mixture of epoxides, usually in the presence of an inert diluent, while maintaining a temperature of about 25 C. up to the decomposition temperature of the ester or epoxide involved and usually at a temperature within a range of about 50250 C. Good results are achieved when the posttreatment is conducted at a temperature of about 70- 200 C. The esters and epoxides are easily brought into contact simply by mixing them in any convenient manner. It is usually desirable to employ some type of mechanical agitation to facilitate thorough contact of the esters and epoxides.

Any substantially inert organic liquid can be used as a diluent. Suitable diluents include the aliphatic, cycloaliphatic, and aromatic hydrocarbons and their chlorinated analogs exemplified by pentane, hexane, heptane, cyclohexane, benzene, toluene, xylene, chlorobenzene, chlorohexanes, and the like. Mineral oils, naphthas, ligroin, and the like may also be used as a diluent. In many instances, the esters are prepared as oil-solutions and these oilsolutions can be used in the post-treating process, the oil functioning as a diluent.

The precise means by which this process improves the dispersancy characteristics of the esters is not known. The epoxides are believed to react with nonesterified hydroxyl groups although they may also react with any free carboxyl groups present. In a preferred aspect of the invention, the esters to be post-treated will be substantially free from unreacted carboxyl groups, for example, the diesters of the succinic acids as opposed to the acidic esters. This usually can be achieved by using esterification catalyst and a stoichiometric excess of hydroxy aromatic compound in preparing the esters. An ester is considered substantially free from free carboxyl groups for purposes of this invention when not more than about of the number of carboxyl functions present are free carboxyl groups, i.e., COOH. Ordinarily the number of free carboxyl groups will be less than about 5% of the total number in the ester composition being treated in this preferred aspect of the invention. When free carboxyl groups are present on esters to be post-treated, the amount of epoxide employed may be increased to provide up to about one equivalent of epoxide for each equivalent of free carboxyl group in addition to that used for posttreating the ester.

The esters and epoxides should be contacted in an amount such that the ratio of equivalents of hydroxy aromatic compound present in the ester to the equivalents of epoxide will be about 11005 to about 1:5 and preferably 1:0.l to about 1:2. For purposes of using this ratio, the equivalent weight of a hydroxy aromatic compound is deemed to be its molecular weight divided by the number of hydroxyl groups present whether or not they are esterified. Similarly, the equivalent weight of an epoxide is deemed to be the molecular weight of the epoxide divided by the number of oxirane rings present in the epoxy molecule. By way of example, if the ester to be treated contains one mole of resorcinol in the oxy moiety, the ester is deemed to contain two equivalents of hydroxy aromatic compound. According to the present process, such an ester would be contacted with 0.1 to 10, preferably 0.2 to 4 equivalents of epoxide. This equivalent ratio is offered merely as a guideline to define the elfective ratios of ester and epoxide and is in no way intended to imply that all the epoxide used will react with the ester. However, within this ratio, it is possible to determine the optimum ratio of ester and epoxide for any given ester or combination of esters and any given epoxide or combination of epoxides through routine evaluation.

The following examples illustrate the epoxide posttreatment of the esters of this invention.

EXAMPLE 11 An oil solution of an ester prepared according to Example 2 is contacted with propylene oxide in an amount such that the equivalent ratio of hydroxy aromatic compound in the ester reaction product to epoxide (as explained above) is about 1:1. The mixture is heated for seventeen hours at -90 C. and then stripped at reduced pressure to remove any unreacted propylene oxide. The resulting mixture is then filtered producing an oil solution of the desired post-treated ester.

EXAMPLE 12 The ester product of Example 10 is post-treated with an equimolar mixture of ethylene oxide and propylene oxide in an amount such that the equivalent ratio of hydroxy aromatic compound to alkylene oxide is 1:3. The temperature of the reaction mass is maintained at C. for four hours, stripped at reduced pressure, and filtered. The filtrate is an oil-solution of the desired posttreated ester.

By following the general procedures of Examples 11 and 12 and utilizing different esters, different epoxides, or different esters and epoxides, other post-treated esters of the type contemplated by the present invention are readily prepared.

The esters and post-treated esters of this invention are useful for a wide variety of purposesas pesticides, plasticizers, rust-inhibiting agents, corrosion-inhibiting agents, extreme pressure agents, detergents, hydrocarbon fuel additives, etc.

A principal utility of the esters is as additives in lubricants, especially lubricating oils. The lubricating oils in which the esters of this invention are useful as additives may be of synthetic, animal, vegetable, or mineral origin. Ordinarily, mineral lubricating oils are preferred by reason of their availability, general excellence, and low cost. For certain applications, oils belonging to one of the other three groups may be preferred. For instance, synthetic polyester oils such as didodecyl adipate and di-2-ethylhexyl sebacate are often preferred as jet engine lubricants. Normally, the lubricating oils preferred will be fluid oils ranging in viscosity from about 40 Saybolt Universal seconds at 100 F. to about 200 Saybolt Universal seconds at 210 F.

The concentration of the esters as additives in lubricants usually ranges from about 0.01% to about 10% by weight. The optimum concentration for a particular application depends to a large extent upon the type of service to which the lubricants are to be subjected. Thus, for example, lubricants for use in gasoline engines may contain from about 0.5 to about 5% of the additive whereas lubricating compositions for use in gears and diesel engines may contain as much as or even more of the additive.

This invention contemplates also the presence of other additives in the lubricating compositions. Such additives include, for example, supplemental detergents of the ashcontaining type, viscosity index improving agents, pour point depressing agents, anti-foam agents, extreme pressure agents, rust-inhibiting agents, and supplemental oxidation and corrosion-inhibiting agents.

The ash-containing detergents are exemplified by oilsoluble neutral and basic salts of alkali or alkaline earth metals with sulfonic acids, carboxylic acids, or organic phosphorus acids characterized by at least one direct carbon-to-phosphorus linkage such as those prepared by the treatment of an olefin polymer (e.g., polyisobutene having a molecular weight of 1000) with a phosphorizing agent such as phosphorus trichloride, phosphorus heptasulfide, phosphorus pentasulfide, phosphorus trichloride and sulfur, white phosphorus and a sulfur halide, or phosphorothioic chloride. The most commonly used salts of such acids are those of sodium, potassium, lithium, calcium, magnesium, strontium, and barium.

The term basic salt is used to designate the metal salts wherein the metal is present in stoichiometrically larger amounts than the organic acid radical. The commonly employed methods for preparing the basic salts involves heating a mineral oil solution of an acid with a stoichiometric excess of a metal neutralizing agent such as the metal oxide, hydroxide, carbonate, bicarbonate, or sulfide at a temperature about 50 C. and filtering the resulting mass. The use of a promoter in the neutralization step to aid the incorporation of a large excess of metal likewise is known. Examples of compounds useful as the promoter include phenolic substances such as phenol, naphthol, alkylphenol, thiophenol, sulfurized alkylphenol, and condensation products of formaldehyde with a phenolic substance, alcohols such as methanol, 2- propanol, octyl alcohol, Cellosolve, Carbitol, ethylene glycol, stearyl alcohol, and cycohexyl alcohol; amines such as aniline, phenylenediamine, phenothiazine, phenyl-betanaphthyl-amine, and dodecylamine, A particularly effective method for preparing the basic salts comprises mixing an acid with an excess of a basic alkaline earth metal neutralizing agent, a phenolic promoter compound, and a small amount of Water and carbonating the mixture at an elevated temperature such as 60200 C.

The esters of this invention are especially adapted for use in combination with extreme pressure and corrosioninhibiting additives such as metal dithiocarbamates, xanthates, the Group II metal phosphorodithioates and their epoxide adducts, hindered phenols, sulfurized cycloalkanes, di-alkyl polysulfides, sulfurized fatty esters, phosphosulfurized fatty esters, alkaline earth metal salts of alkylated phenols, dialkyl phosphites, triaryl phosphites, and esters of phosphorodithioic acids. Combinations of the esters of this invention with any of the above mentioned additives are especially desirable for use in lubricants which must have superior extreme pressure and oxidation-inhibiting characteristics.

The Group II metal phosphorodithioates are the salts of acids having the formula in which R and R are substantially hydrocarbon radicals. The metals for forming such salts are exemplified by barium, calcium, strontium, zinc, and cadmium. The barium and zinc phosphorodithioates are especially preferred. The substantially hydrocarbon radicals in the phosphorodithioic acid are preferably low or medium molecular weight alkyl radicals and alkylphenyl radicals, i.e., those having from about 1 to about 30 carbon atoms in the alkyl group. Illustrative alkyl radicals include methyl, ethyl, isopropyl, isobutyl, n-butyl, secbutyl, the various amyl alcohols, n-hexyl methylisobutyl carbinyl, heptyl, 2-ethylhexyl, diisobutyl, isooctyl, nonyl, behenyl, decyl, etc. Illustrative lower alkylphenyl radicals include butylphenyl, amylphenyl, di-amylphenyl, octylphenyl, etc. Cycloalkyl radicals likewise are useful and these include chiefly cyclohexyl and the lower alkyl-cyclohexyl radicals. Other substantially hydrocarbon radicals likewise are useful such as tetradecyl, octadecyl, eicosyl, butylnaphthyl, hexylnaphthyl, octylnaphthyl, cyclohexylphenyl, naphthenyl, etc. Many substituted hydrocarbon radicals may also be used, e.g., chloropentyl, dichlorophenyl, and dichlorodecyl.

Especially useful Group II metal phosphorodithioates can be prepared from phosphorodithioic acids which in turn are prepared by the reaction of phosphorus pentasulfide with mixtures of alcohols. The use of such mixtures enables the utilization of cheaper alcohols which in themselves do not yield oil-soluble phosphorodithioic acids. Thus a mixture of isopropyl and hexyl alcohols can be used to produce a very effective, oil-soluble metal phosphorodithioate. For the same reason mixtures of simple phosphorodithioic (i.e., acids prepared from one alcohol) acids can be reacted with zinc oxide or barium oxide to produce less expensive, oil-soluble salts.

Another class of the phosphorothioate additives con templated for use in the lubricating compositions of this invention comprises the adducts of the metal phosphorodithioates described above with an epoxide. The metal phosphorodithioates useful in preparing such adducts are for the most part the zinc phosphorodithioates. The epoxides may be alkylene oxides or arylalkylene oxides. The arylalkylene oxides are exemplified by styrene oxide, p-ethylstyrene oxide, alpha-methylstyrene oxide, 3-beta-naphthyl- 1,3-butylene oxide, m-dodecylstyrene oxide and p-chlorostyrene oxide. The alkylene oxides include principally the lower alkylene oxides in which the alkylene radical contains 6 or less carbon atoms such as illustrated hereinbefore.

The adduct may be obtained by simply mixing the phosphorodithioate and the epoxide. The reaction is usually exothermic and may be carried out within wide temperature limits from about 0 C. to about 200 C. Because the reaction is exothermic it is best carried out by adding one reactant, usually the epoxide, in small increments to the other reactant in order to obtain convenient control of the temperature of the reaction. The reaction may be carried out in a solvent such as benzene, mineral oil, naphtha, or n-hexane.

The chemical structure of the adduct is not known. More than one mole, sometimes as many as four moles, of the epoxide can be made to combine with the phosphorodithioate to form products useful herein. However, adducts obtained by the reaction of one mole of the phosphorodithioate with from about 0.25 mole to about 1 mole of a lower alkylene oxide, particularly ethylene oxide and propylene oxide, have been found to be especially useful and therefore are preferred.

The lubricating compositions may contain metal detergent additives in amounts usually within the range of from about 0.1% to about 20% by weight. In some applications such as in lubricating marine diesel engines the lubricating compositions may contain as much as 30% of a metal detergent additive. They may contain extreme pressure addition agents, viscosity index improving agents, and pour point depressing agents, each in amounts within the range from about 0.1% to about 10%.

The following examples are illustrative of the lubricating compositions of this invention: (all percentages are by weight.

EXAMPLE A SAE 20 mineral lubricating oil containing 0.5% of the product of Example 2.

EXAMPLE B SAE 30 mineral lubricating oil containing 0.75% of the product of Example 2 and 0.1% of phosphorus as the barium salt of di-n-nonylphosphorodithioic acid.

EXAMPLE C SAiE 10W-30 mineral lubricating oil containing 0.4% of the product of Example 3.

EXAMPLE D SAE 20W30 mineral lubricating oil containing of the product of Example 8.

EXAMPLE E SAE W-30 mineral lubricating oil containing 1.5% of the product of Example 4 and 0.05% of phosphorus as the zinc salt of a phosphorodithioic acid prepared by the reaction of phosphorus pentasulfide with a mixture of 60% (mole) of p-butylphenol and 40% (mole) of npentyl alcohol.

EXAMPLE F SAE 10W-30 mineral lubricating oil containing 2% of the product of Example 7, 0.06% of phosphorus as zinc di-n-octylphosphorodithioate, and 1% of sulfate ash as barium mahogany sulfonate.

EXAMPLE G SAE 30 mineral lubricating oil containing 5% of the product of Example 11, 0.1% of phosphorus as the zinc salt of a mixture of equi-molar amounts of di-isopropylphosphorodithioic acid and di-n-decylphosphorodithioic acid, and 2.5% of sulfate ash as a basis barium detergent prepared by carbonating at 150 C. a mixture comprising mineral oil, barium di-dodecylbenzene sulfonate and 1.5 moles of barium hydroxide in the presence of a small amount of water and 0.7 mole of octylphenol as the promoter.

EXAMPLE H SAE 10W-30 mineral lubricating oil containing 6% of the product of Example 12, 0.075% of phosphorus as zinc di-n-octylphosphorodithioate, and 5% of the barium salt of an acidic composition prepared by the reaction of 1000 parts of a polyisobutene having a molecular weight of 60,000 with 100 parts of phosphorus pentasulfide at 200 C. and hydrolyzing the product with steam at 150 C.

EXAMPLE I SAE 10 mineral lubricating oil containing 3% of the product of Example 6, 0.075% of phosphorus as the zinc salt of a phosphorodithioic acid prepared by the reaction of phosphorus pentasulfide with an equi-molar mixture of n-butyl alcohol and dodecyl alcohol, 3% of a barium detergent prepared by carbonating a mineral oil solution containing 1 mole of sperm oil, 0.6 mole of octylphenol, 2 moles of barium oxide, and a small amount of water at 150 C.

The above lubricating compositions are merely illustrative and the scope of the invention includes the use of all of the additives previously illustrated as well as others 'within the broad concept of this invention described herein.

Fuel compositions of the type contemplated by the present invention are illustrated by the following examples. Ordinarily the esters are used in amounts such that they will comprise from about 0.001% to about 5%, usually 0.01% to 2%, by weight of the final fuel. It is also contemplated that the fuels may contain other conventional additives such as deicers, smoke suppressants, lead scavengers, demulsifiers, lead appreciators, anti-rust agents, and the like.

EXAMPLE I Gasoline containing 0.015% of the esters produced according to Example 11.

16 EXAMPLE K Kerosene containing 0.05% of the ester produced according to Example 2.

EXAMPLE L Diesel fuel containing 0.5% of the ester produced according to Example 6.

EXAMPLE M No. 2 fuel oil for oil furnaces comprising 0.1% of the ester produced according to Example 3.

What is claimed is:

1. A lubricating composition comprising a major amount of a lubricating oil and an amount, sufficient to impart detergency thereto, of at least one oil-soluble ester of a hydroxy aromatic compound selected from the group consisting of phenols and naphthols and a substantially saturated monoor polycarboxylic acid or anhydride wherein the acyl moiety of said ester corresponds to the acyl radical of an acid or anhydride derived from the reaction of a polyolefin or chloroinated polyolefin containing at least about 50 aliphatic carbon atoms with an alpha, beta-unsaturated monoor dicarboxylic acid or anhydride.

2. A lubricating composition according to claim 1 wherein the acyl moiety of said ester is an acyl radical of a polyolefin-substituted succinic acid derived from the reaction of a polyolefin or chlorinated polyolefin with maleic acid or anhydride, the ester being a monoester, diester, or mixture of these.

3. A lubricating composition according to claim 2 wherein the hydroxy aromatic compound is a monohydroxy or polyhydroxy phenol selected from the class consisting of phenols, alkylphenols, phenol ethers, and alkylene bis-phenols.

4. A lubricating composition according to claim 3 wherein the acyl moiety is an acyl radical of a succinic acid derived from the reaction of a polymerized l-monoolefin or a chlorinated polymerized l-monoolefin having an average molecular meight of about 700 to about 5000 with maleic anhydride or maleic acid.

5. A lubricating composition according to claim 2 wherein the aromatic hydroxy compound is an aliphatic hydrocarbon-substituted monohydroxy or polyhydroxy phenol.

6. A lubricating composition according to claim 5 wherein the acyl moiety is an acyl radical or a polyisobutenyl-substituted succinic acid.

7. A lubricating composition according to claim 1 wherein the acyl moiety is an acyl radical of a monocarboxylic acid having an average molecular weight of about 700 to about 5000 and wherein the hydroxy aromatic compound is a monohydroxy or polyhydroxy phenol.

8. A lubricating composition according to claim 7 wherein the monohydroxy or polyhydroxy phenol is an aliphatic hydrocarbon-substituted monohydroxy or polyhydroxy phenol.

9. A lubricating composition according to claim 1 wherein said at least one oil-soluble ester is an epoxidepost-treated ester prepared by reacting at least one ester with a terminal epoxide of the formula D P nn-(3H wherein one R. is hydrogen and the other R is hydrogen, phenyl, halophenyl, alkyl, or haloalkyl at a temperature of about 25 C.

10. A fuel composition comprising a major amount of a normally liquid petroleum distillate fuel and an amount, sufiicient to impart detergency thereto, of an oil-soluble ester of a hydroxy aromatic compound selected from the group consisting of phenols and naphthols and a substantially saturated monoor dicarboxylic acid or an- 17 v hydride wherein the acyl moiety of said ester corresponds to the acyl radical of an acid or anhydride derived from the reaction of a polyolefin or chlorinated polyolefin having at least 50 aliphatic carbon atoms with an alpha, betaunsaturated monoor dicarboxylic acidor anhydride.

11. A fuel composition according to claim wherein the acyl moiety of the ester is an acyl radical of a polyisobutenyl-substituted succinic acid or anhydride derived from the reaction of polyisobutene or chlorinated polyisobutene having an average molecular Weight of about 700 to about 5000 with maleic acid or maleic anhydride and wherein the hydroxy aromatic compound is a monohydroxy or polyhydroxy phenol.

12. A fuel composition according to claim 10 wherein at least one oil-soluble ester is an epoxide post-treated ester prepared by reacting said at least one ester with an epoxide of the formula 18 where one R is hydrogen and the other R is hydrogen, phenyl, halophenyl, alkyl, or haloalkyl at a temperature of about C. up to the decomposition temperature of the ester or epoxide in an equivalent ratio of ester to epoxide of 1:05 to 1:5.

References Cited PATRICK P. GARVIN, Primary Examiner W. H. CANNON, Assistant Examiner U8. 0]. X.R. 4462, 25256 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 542 680 DATE I November 24, 1970 INVENTOR( I William M. LeSuer It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown bE|0WI At column 2, between lines 56 and 60, the formula Signed and Scaled thi:

A "as t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmlssiunvr nj'lau'nrs and Trudcmur