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Publication numberUS3403102 A
Publication typeGrant
Publication dateSep 24, 1968
Filing dateMar 7, 1967
Priority dateMay 17, 1963
Also published asDE1520211A1
Publication numberUS 3403102 A, US 3403102A, US-A-3403102, US3403102 A, US3403102A
InventorsSuer William M Le
Original AssigneeLubrizol Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Lubricant containing phosphorus acid esters
US 3403102 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

United States Patent Office 3,403,102 Patented Sept. 24, 1968 3,403,102 LUBRICANT CONTAINING PHOSPHORUS ACID ESTERS William M. Le Suer, Cleveland, Ohio, assignor to The Lubrizol Corporation, Wicklilfe, Ohio, a corporation of Ohio N Drawing. Original application May 17, 1963, Ser. No. 281,329, now Patent No. 3,325,567, dated June 13, 1967. Divided and this application Mar. 7, 1967, Ser. No. 621,136

14 Claims. (Cl. 25249.8)

ABSTRACT OF THE DISCLOSURE Lubricants, especially lubricants for internal combustion engines and gears, are prepared by blending a lubricating oil and a phosphorus-containing ester. Such lubricants have improved oxidation resistance and detergent properties. The phosphorus-containing ester is prepared by reacting a polyhydric alcohol with both a high molecular weight substituted succinic reactant having at least about 50 aliphatic carbon atoms in the substituent and a phosphorus reactant which may be phosphorus pentoxide, phosphoric acid, or an alkyl ester of phosphoric acid. The preferred phosphorus-containing ester is illustrated by the product formed by reacting pentaerythritol first with a polyisobutene-substituted succinic anhydride and then with triphenylphosphite.

This application is a division of c-opending application Ser. No. 281,329 filed May 17, 1963, now US. 3,325,567.

issued June 13, 1967.

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 break-down 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 the mayonnaiselike 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, home to 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 eifective 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 are attained in accordance with this invention by providing a process for preparing phosphorus-containing esters comprising the reaction of one mole of a polyhydroxy compound having the formula wherein R is a hydrocarbon radical and x is an integer greater than one with from about 0.5 to x moles of an acid-producing mixture of (A) a succinic acid-producing compound selected from the class consisting of hydrocarbon-substituted succinic acids and the halides, the esters, and the anhydrides thereof having at least about 50 aliphatic carbon atoms in the hydrocarbon substituent and (B) a phosphorus acid-producing compound selected from the class consisting of phosphoric acids, phosphorus acids, and the halides, the esters, and the anhydrides thereof, the molar ratio of said succinic acid-producing compound to said phosphorus acid-producing compound being within the range of from about 0.1 :1 to 10:1.

The polyhydroxy compounds from which the phosphorus-containing esters of this invention are derived include principally polyhydric alcohols and polyhydric phenols. They preferably contain less than about 30 carbon atoms. The polyhydric alcohols having from about 2 to 12 carbon atoms and having from 2 to about 10 hydroxy radicals, preferably from 3 to 6 hydroxy radicals, are especially useful. They are illustrated by, for example, alkylene glyc-ols and poly(oxy-alkylene)glycols such as ethylene glycol, di(ethylene glycol), tri(ethylene glycol), di(propylene glycol), tri(butylene glycol), penta(ethylene glycol) and other poly(oxy-alkylene)glycols formed by the condensation of two or more moles of ethylene glycol, propylene glycol, octylene glycol, or a like glycol having up to about 12 carbon atoms in the alkylene radical. Other useful polyhydric alcohols include glycerol, pentaerythritol, 2,4-hexanediol, pinacol, erythritol, arabitol, sorbitol, mannitol, 1,2-cyclohexanediol, Xylylene glycol, and 1,3,5-cyclohexanetriol. The polyhydric phenols are exemplified by hydroquinone, resorcinol, 4-heptyl-1,2- di-hydroxy-benzene, 1,2 dihydroxy naphthalene, 4-polypropene (molecular weight of 1500)-substituted 1,2-dihydroxy-benzene, methyl-S-decyl-1,2-dihydroxy-naphthalene, and pyrogallol.

Still other polyhydroxy compounds include the monoesters of glycerol, sorbitol, mannitol, or other higher polyhydroxy alcohols, such as mono-acetate of glycerol, mono-oleate of sorbitol mono-propionate of mannitol, or the like. Also useful are the interpolymers of an unsaturated alcohol with a copolymerizable olefinic substance such as styrene, vinyl ether, vinyl acetate, isobutene, butadiene, di-vinylbenzene or the like. The interpolymers contain two or more monomeric units derived from the unsaturated alcohol and thus constitute the Polyhydric alcohols contemplated for use in the process of this invention. Specific examples of such interpolymers are the copolymer of 5 moles of allyl alcohol and 1 mole of styrene having an average molecular weight of about 2500.

The radical R in the formula of the polyhydroxy compounds designates a radical which is substantially hydrocarbon in character. The radical may be a hydrocarbon radical or a polar-substituted hydrocarbon radical. Thus, the radical may contain inert polar groups provided that such groups are not present in proportions sufiiciently large to alter significantly the hydrocarbon character of the radical. The polar groups are exemplified by chloro, bromo, keto, aldehyde, nitro, etc. The upper limit with respect to the proportion of such polar groups in a hydrocarbon radical is usually about based upon the weight of the hydrocarbon portion of the radical. In lieu of such a hydrocarbon group, an ether-containing hydrocarbon group may be used wherein the ether groups such as oxyalkylene or poly(oxy-alkylene) groups may contain as many as one oxygen atom for each two carbon atoms.

The hydrocarbon-substituted succinic acid-producing compounds useful in preparing the phosphorus-containing esters may be the succinic acids, anhydrides, halides, or esters in which the hydrocarbon substituent contains at least about 50 aliphatic carbon atoms. The sources of the hydrocarbon substituent include principally the high molecular weight substantially saturated petroleum fractions and substantially saturated olefin polymers, particularly polymers of mono-olefins having from 2 to 30 carbon atoms. The especially useful polymers are the polymers of l-mono-olefins such as ethylene, propene, l-butene, isobutene, l-hexene, l-octene, 2-methyl-1- heptene, 3-cyclohexyl-1-butene, and 2-methyl-5-propyl-1- hexene. Polymers of medial olefins, i.e., olefins in which the olefinic linkage is not at the terminal position, likewise are useful. They are illustrated by 2-butene, 3-pentene, and 4-octene.

Also useful are the interpolymers of the olefins such as those illustrated above with other interpolymerizable olefinic substances such as aromatic olefins, cyclic olefins, and polyolefins. Such interpolymers include, for example, those prepared by polymerizing isobutene with styrene; isobutene with butadiene; propene with isoprene; ethylene with piperylene; isobutene with chloroprene; isobutene with p-methyl styrene; l-hexene with 1,3-hexadiene; l-octene with l-hexene; l-heptene with l-pentene; 3- methyl-l-butene with l-octene; 3,3-dimethyl-l-pentene with l-hexene; isobutene with styrene and piperylene; etc.

The relative proportions of the mono-olefins to the other monomers in the interpolymers influence the stability and oil-solubility of the final products derived from such interpolymers. Thus, for reasons of oil-solubility and stability the interpolymers contemplated for use in this invention should be substantially aliphatic and substantially saturated, i.e., they should contain at least about 80%, preferably at least about 95%, on a weight basis, of units derived from the aliphatic mono-olefins and no more than about 5% of olefinic linkages based on the total number of carbon-to-carbon covalent linkages. In most instances, the percentage of olefinic linkages should be less than about 2% of the total number of carbonto-carbon covalent linkages.

Specific examples of such interpolymers include the copolymer of 95% (by weight) of isobutene with 5% of styrene; the terpolymer of 98% of isobutene with 1% of piperylene and 1% of chloroprene; the terpolymer of 95% of isobutene with 2% of l-butene and 3% of l-hexene; the terpolymer of of isobutene with 10% of l-pentene and 10% of l-octene; the copolymer of 80% of l-hexene and 20% of l-heptene; the terpolymer of of isobutene with 2% of cyclohexene and 8% of propene; and the copolymer of 80% of ethylene and 20% of propene.

Another source of the hydrocarbon radical comprises saturated aliphatic hydrocarbons such as highly refined high molecular weight White oils or synthetic alkanes such as are obtained by hydrogenation of high molecular weight olefin polymers illustrated above or high molecular weight olefinic substances.

The use of olefin polymers having molecular weights of about 750-5000 is preferred. Higher molecular weight olefin polymers having molecular weights from about 10,000 to about 100,000 or higher have been found to impart viscosity index improving properties to the final products of this invention. The use of such higher molecular weight olefin polymers often is desirable. It will be noted that the hydrocarbon substituent in the succinic acid-producing compound likewise may contain inert polar groups. Thus, in this respect, it may be a radical which is substantially hydrocarbon in character such as is referred to in the above description of the hydrocarbon radical R of the polyhydroxy compounds.

The succinic acid-producing compounds useful in the above process are preferably substantially hydrocarbonsubstituted succinic acids and anhydrides. These succinic compounds are readily available from the reaction of maleic anhydride with a high molecular weight olefin or a chlorinated hydrocarbon such as the olefin polymer described hereinabove. The reaction involves merely heating the two reactants at a temperature about 100- 200 C. The product from such a reaction is an alkenyl succinic anhydride. The alkenyl group may be hydrogenated to an alkyl group. The anhydride may be hydrolyzed by treatment with water or steam to the corresponding acid. Either the anhydride or the acid may be converted to the corresponding acid halide or ester by reaction with, e.g., phosphorus halide, phenols, or alcohols.

In lieu of the olefins or chlorinated hydrocarbons, other hydrocarbons containing an activating polar substituent, i.e., a substituent which is capable of activating the hydrocarbon molecule in respect to reaction with maleic acid or anhydride, may be used in the above-illustrated reaction for preparing the succinic compounds. Such polar substituents may be illustrated by sulfide, disulfide, nitro, mercaptan, bromine, kctone, or aldehyde radicals. Examples of such polar-substituted hydrocarbons include polypropene sulfide, di-polyisobutene disulfide, nitrated mineral oil, di-polyethylene sulfide, brominated polyethylene, etc. Another method useful for preparing the succinic acids and anhydrides involves the reaction of itaconic acid with a high molecular weight olefin or a polar-substituted hydrocarbon at a temperature usually within the range from about 100 C. to about 200 C.

The acid halides of the succinic acids can be prepared by the reaction of the acids or their anhydrides with a halogenation agent such as phosphorus tri-bromide, phosphorus pentachloride or thionyl chloride. The esters of such acids can be prepared simply by the reaction of the acids or their anhydrides with an alcohol or a phenolic compound such as methanol, ethanol, octadecanol, cyclohexanol, phenol, naphthol, octylphenol, etc. The esterification is usually promoted by the use of an alkaline catalyst such as sodium hydroxide or sodium alkoxide or an acidic catalyst such as sulfuric acid. The nature of the alcoholic or phenolic portion of the ester radical appears to have little influence on the utility of such ester as reactant in the process described hereinabove.

The phosphorus acid-producing reactants useful in the above process for forming the phosphorus-containing esters of this invention may be acids, anhydrides, esters, or halides. The phosphorus acids may be phosphoric acids and phosphorous acids including the oxyphosphorus acids, the thiophosphorus acids, as well as the mixed oxythiophosphorus acids (i.e., those containing both oxygen and sulfur). Thus, a phosphoric acid is used in a generic sense to denote the class consisting of phosphoric acid (H PO phosphorotetrathioic acid (H PS phosphoromonothioic acid (H PO S), phosphorodithioic acid (H PO S and phosphorotrithioic acid (H -POS It should be noted that the acids containing both oxygen and sulfur may be further characterized according to the manner in which the oxygen or sulfur is attached to the phosphorus atom of the acid. The nomenclature used here follows essentially that proposed by the American Chemical and Engineering News, volume 30, No. 43, Oct. 27, 1952. According to this nomenclature, for instance, a phosphoromonothioic acid in which the sulfur atom is attached only to the phosphorus atom (i.e., -P(S) (OH)) is a phosphorothionic acid whereas its isomer in which the sulfur atom is attached to both the phosphorus atom and a hydrogen atom (i.e., --P(O)(S-H)) is a phosphorothiolic acid. Also according to this nomenclature, the inclusion of the thio analogs is admitted only when generic expressions are used and the specific designations such as dioctylphosphoric acid and diphenylphosphorous acid refer to oxy-compounds only, i.e., (octylO) P(O)'(OH) and (octyl-O) POH, respectively. To illustrate further phosphoric acid describes H PO whereas phosphoric,

acids may be the oxy and thio acids. Thus, dialkylphosphoric acids, i.e., dialkyl esters of phosphoric acids, include dialkylphosphoric acid ((alkyl-O) 'P(O) (OH)); dialkylphosphorotetrathioic acid ((alkyl-S) P(S) (SH) 0,0-dialkylphosphorodithioic acid y )z H) O,S-dialkylphosphorodithionic acid ((alkyl-O)(alkyl-S)P(S)(OH)) O,S-dialkylphosphorodithiolic acid ((alkyl-O) (alkyl-S)'P(O) (SH) O,S-dialkylphosphorotrithioic acid The phosphorus acid anhydrides, esters, and halides likewise are useful for preparing the phosphorus-containing esters of this invention. The anhydrides of phosphorus acids are especially desirable. They are illustrated by phosphorus pentoxide, phosphorus pentasulfide, phosphorus heptasulfide, phosphorus sesquisulfide, and phos phorus oxysulfide. The anhydrides of organic phosphorus acids are exemplified by the anhydrides of diphenylphosphoric acid, etc. The halides of the phosphorus acids include, for instance, phosphorus trichloride, phosphorus pentachloride, phosphorothioic trichloride, phosphorus tribromide, diphenylphosphorus chloride, 0,0'-di(chlorophenyl)phosphorothioic chloride, 0,0'-diphenylphosphorothioic chloride, and diphenylphosphorus trichloride.

The esters of the phosphorus acids may be the completely esterified acids or partially esterfied acids. The latter are also known as acidic esters, i.e., at least a portion of the acid is not esterified; they are illustrated by the monoor the di-esterified phosphoric or phosphorous acids. The ester portion may be derived from a hydrocarbon radical, usually one having less than about 30 and preferably from about 1 to about 24 aliphatic carbon atoms. The hydrocarbon radicals may contain inert polar groups such as are described previously. They are exemplified by methyl, ethyl, chloromethyl, o-chlorophenyl, p-bromophenyl, alpha-chloronaphthyl, beta-heptylnaphthyl, o,p-dimethoxyphenyl, tolyl, isobutyl, octadecyl, 4- chloro-2-hep-tadecyl, eicosyl, naphthyl, benzyl, chlorobenzyl, 2-pheny1ethyl, cyclohexyl, cyclopentyl, Z-methylcyclohexyl, the hydrocarbon radical derived from polypropene having a molecular weight of 1500, the hydrocarbon radical derived from polyisobutene having a molecular weight of 5000, behenyl, stearyl, oleyl, allyl, propargyl, o-heptylphenyl, 2,4,6-trirnethylphenyl, Z-mercaptophenyl, m-nitrophenyl, methoxytetraethoxy-methyl, 10- keto-l-octadecyl, polyisobutene (molecular weight of 1000)-substituted phenyl, xenyl, S-naphthyl-Z-decyl, l0- tolyl-l-stearyl, and 9,10-dichlorostearyl radical.

The commonly used esters are, for example, methyl ester of phosphoric acid, dimethyl ester of phosphoric acid, trimethyl ester of phosphoric acid, O-methyl ester of phosphorothiolic acid, dicyclohexyl ester of phosphoric acid, 0,0-dicyc1ohexyl ester of phosphorodithioic acid, dicyclohexyl ester of phosphorotetrathioic acid, O-cyclohexyl-S-decyl ester of phosphoromonothioic acid, 0,0'-diphenyl ester of phosphoromonothiolic acid, triphenyl ester of phosphoric acid, triphenyl ester of phosphorus acid, tritolyl ester of phosphoric acid, dioctadecyl ester of phosphorus acid, trinaphthyl ester of phosphorus acid, trinaphthyl ester of phosphoric acid, 0,0'-dinaphthyl ester of phosphoromonothionic acid, 0,0'-dinaphthyl ester of phosphorothiolic acid, di(heptylphenyl) ester of phosphoric acid, bis(dichlorophenyl) ester of phosphorous acid, S-benzyl ester of phosphoromonothiolic acid, S,S'- di(phenylethyl) ester of phosphorodithioic acid, O,S-didecyl ester of phosphorotrithiolic acid, S,S'-didodecyl ester of phosphorotrithiolic acid, diphenyl ester of phosphorotetrathioic acid, O-dodecyl-S-phenyl ester of phosphoromonothiolic acid, 0,0'-diisooctyl ester of phosphorodithioic acid, di(nitrophenyl) ester of phosphoric acid, 0,0'-di(nitrophenyl) ester of phosphorodithioic acid, 0,0'-di(methoxyphenyl) ester of phosphorodithioic acid, 0,0-di(methoxyphenyl) ester of phosphorodithioic acid, di(heptylphenyl-(OC H ester of phosphoric acid, di(methyl-(OC ;H ester of phosphoric acid, decyl octadecyl ester of phosphoric acid, di(4ketol-decyl) ester of phosphoric acid, di(polyisobutene (molecular weight of 1500)-substituted phenyl) ester of phosphoric acid, 0,0'-di(polypropene (molecular weight of 300)-substituted naphthyl) ester of phosphorodithioic acid, and oleyl ester of phosphoric acid.

The esters of phosphoric acid and phosphorothioic acids are obtained by the reaction of phenol or an alcohol with phosphoric acid or a phosphorothioic acid, or an anhydride of the acid such as phosphorus pentoxide, phosphorus pentasulfide, or phosphorus oxysulfide. The reaction is usually carried out simply by mixing the reactants at a temperature above about 50 C., preferably between about C. and C. In many instances, however, the esters of phosphoric acids tend to decompose at high temperatures. Thus it is often desirable to avoid prolonged exposure of the reaction mixture to temperatures above about 150 C. A solvent may be used in the reaction to facilitate mixing of the reactants and control of the reaction temperature. The solvent may be benzene, naphtha, chlorobenzene, mineral oil, kerosene, cyclohexane, or carbon tetrachloride. A solvent capable of forming a rela tively lowboiling azeotrope with water further aids the removal of water in the esterification of an alcohol or phenol with the phosphorus acid reactant. The relative amounts of the alcohol or phenol reactant and the acid reactant influence the nature of the ester obtained. For instance, equimolar amounts of an alcohol and phosphoric acid tend to result in the formation of a monoester of phosphoric acid whereas the use of a molar excess of the alcohol reactant in the reaction mixture tends to increase the proportion of the .diester or triester in the product. In

most instances the product will be a mixture of the mono-, di-, and tri-esters of the acid and such a mixture is desirable for use in this invention for reasons of economy.

The reaction of an alcohol or phenol with phosphorus pentasulfide ordinarily results in 0,0'-diester of phosphorodithioic acid. Such reaction involves four moles of the alcohol or phenol per mole of phosphorus pentasulfide and may be carried out within the temperature range from about 50 C. to about 250 C. Thus, the preparation of 0,0'-di-n-hexylphosphorodithioic acid involves the reaction of phosphorus pentasulfide with four moles of n-hexyl alcohol at about 100 C. for about 2 hours. Hydrogen sulfide is liberated and the residue is the defined acid. Treatment of the phosphorodithioic acid with water or steam removes one or both sulfur atoms and converts the product to the corresponding phosphoromonothioic acid or phosphoric acid.

The esters of phosphorotetrathioic acid can be prepared by first the reaction of a mercaptan or thiophenol with PSCl or PSBr to produce an intermediate which is either a phosphorotrithioic halide or triester of phosphorotetrathioic acid and the subsequent reaction of the intermediate with hydrogen sulfide or sodium hydrosulfide. The esters of phosphorotrithioic acids are obtained by the treatment of the esters of the phosphorotetrathioic acids with water or steam.

The esters of phosphorous acids are obtained by the reaction of an alcohol or phenol With phosphorous acid or a phosphorus trihalide such as phosphorus tribromide or phosphorus trichloride and the above noted reaction usually requires carefully controlled conditions such as low temperature in order to give a substantial yield of the esters of phosphorous acids. Under other conditions the reaction of an alcohol or phenol with a phosphorus trihalide may result in a phosphonic acid or ester. Such esters are readily susceptible to rearrangement to phosphonic acids and esters.

The reaction by which the phosphorus-containing esters of this invention are obtained can be effected simply by mixing a polyhydroxy reactant with the succinic acid-producing and the phosphorus acid-producing reactants at the desired temperature. The use of an inert solvent in the reaction is not necessary but often desirable, especially when a highly viscous or solid reactant is present in the reaction mixture. The inert solvent useful in the reaction may be a hydrocarbon such as benzene, toluene, naphtha, cyclohexane, n-hexane, or mineral oil.

The reaction by which the phosphorus-containing esters of this invention are obtained may be carried out by mixing the polyhydric compound, the hydrocarbon-substituted succinic acid-producing compound, and the phosphOrus acid-producing compound at a temperature above about 100 C., preferably be ween about 125 C. and 250 C. The optimum reaction temperature depends to some extent upon the nature of the specific reactions used. For instance, where the succinic acid-producing compound and the phosphorus acid-producing compound are relatively reactive acids or anhydrides, the reaction temperature may be below about 200 C. On the other hand, if the acid-producing reactants are esters such as the dimethyl esters of hydrocarbon substituted succinic acids and triphenyl esters of phosphoric or phosphorous acids, the reaction temperature often will be 200 C. or higher. The maximum temperature for the process is determined by the decomposition point of the reaction mixture. It rarely exceeds 300 C.

The product resulting from the process of this invention usually is a complex mixture of esters derived from the polyhydroxy reactant by the esterification of some of its hydroxy groups with the succinic acid-producing compound and some other hydroxy groups with the phosphorus acid-producing compounds. Thus, the product of this invention is a complex mixture of esters characterized by the presence of ester radicals of both succinic acid ester type and phosphorus acid ester type. The precise composition of the product is not fully understood. Consequently, the product is best described in terms of the process by which it is formed.

The composition of the product of this invention depends for the most part upon the relative proportions of the three reactants used in the process. For reasons of utility and the stoichiometry of the esterification, the total amount of the succinic acid-producing reactant and the phosphorus acid-producing reactant to be used for each mole of the polyhydroxy reactant ordinarily ranges from about 0.5 mole to as many moles as the number of the hydroxy radicals within the molecular structure of the polyhydroxy reactant. Further, the relative amounts of the succinic acid-producing reactant and the phosphorus acid-producing reactant ordinarily are such that they are within the range of molar ratios from about 0.1 :1 to about 10:1, respectively. To illustrate, in reactions with one mole of a tetrahydroxy compound such as pentaerythritol, there may be employed a mixture of a succinic acidproducing reactant and a phosphorus acid-producing reactant in an amount such that the combined quantity of the two acid-producing reactants ranges from about 0.5 to about 5 moles and that the molar ratio of the succinic acid-producing reactant to the phosphorus acid-producing reactant ranges from about 0.1:1 to about 10:1. In other words, for each mole of a tetrahydroxy reactant there may be employed from about 0.05 mole to about 3.6 moles of a succinic acid-producing reactant and from about 0.05 mole to about 3.6 moles of a phosphorus acidproducing reactant provided that the molar ratio of the succinic acid-producing reactant and the phosphorus acidproducing reactant be within the range of about 0.1:1 to about 10:1. The preferred amounts of the three reactants are such that 1 mole of the polyhydroxy reactant is used with from about 0.5 mole to about 1 mole of a succinic acid-producing reactant and from about 1 mole to 3 moles of a phosphorus acid-producing compound. A specific example of the preferred products of this invention is one obtained by the reaction of 1 mole of pentaerythritol with 1 mole of a succinic anhydride and 2 moles of a triaryl phosphite.

It will be noted that where a reactant is a mixture of two or more individual compounds such as are exemplified by commercial polyhydric alcohols comprising a mixture of tri-, tetra-, penta-, or higher polyhydric alcohols, the molecular weight may be the average molecular weight estimated from the elemental analysis of the mixture. Similarly, in the case of a hydrocarbon-substituted succinic anhydride wherein the hydrocarbon substituent is derived from a mixture of, e.g., olefin polymers, the molecular weight is estimated from the acidity or potential acidity of the anhydride, i.e., it is taken to be twice the equivalent weight based upon the acid number as determinedby a standard procedure for determining the acidity of carboxylic acids or anhydride. The molecular weight of a succinic acid ester likewise may be estimated from the potential acidity as determined by its saponification number. It will be further noted that the lower limit of about 0.5 mole for the combined quantities of the two acid-producing reactants per mole of the polyhydroxy reactant is based upon the stoichiometry for the esterification of only one of the hydroxy groups of the polyhydroxy reactant whereas the upper limit of x number of moles for the combined quantities of the two acid-producing reactants per mole of the polyhydroxy reactant having x number of hydroxy groups is based upon the stoichiometry for the esterification of all of the hydroxy groups of the polyhydroxy reactant.

A preferred mode of carrying out the process of this invention involves reacting a polyhydroxy reactant with the succinic acid-producing reactant to form a partially esterified intermediate and then reacting the intermediate With a phosphorus acid-producing reactant. When the process is carried out in this manner the first step, i.e., the formation of the partially esterified intermediate, is

. 9 preferably eflfected at a temperature between about 100 C. and 200 C. and the second step, i.e., the reaction of the intermediate with the phosphorus reactant may be carried out at a temperature from about 80 C. to about 250 C. This particular mode of carrying out the process of this invention is preferred because the products resulting therefrom have been found to be especially useful for the purposes of this invention such as in hydrocarbon oil and lubricating compositions.

Another alternative mode of carrying out the process of this invention involves first reacting polyhydroxy reactant with a phosphorus acid-producing reactant to form a partially esterified intermediate and then reacting the intermediate with the succinic acid-producing reactant. In this regard, the process admits further variations in forming the intermediate of a polyhydroxy substance which has been partially esterified with a phosphorus acid. Thus, for instance, the reaction of phosphoric acid with an epoxide, particularly an alkylene oxide such as ethylene oxide, propylene oxide, hexylene oxide, or epichlorohydrin may result in a partially esterified glycol, i.e., a glycol having one free hydroxy group and one hydroxy group which has been converted to a phosphorus acid ester group by the esterification with phosphoric acid. A more specific example is found in the reaction of 1 mole of phosphoric acid with 3 moles of propylene oxide resulting in the formation of tri(hydroxypropyl) ester of phosphoric acid. This tri(hydroxypropyl) ester may then be used in reaction with a succinic acid-producing reactant in order to form the phosphorus-containing esters of this invention.

In some instances the formation of the phosphoruscontaining esters by the process of this invention is facilitated by the presence in the process of an esterification catalyst. The well-known esterification catalysts are useful for this purpose. They are illustrated by titanium tetrachloride, aluminum chloride, titanium tetrafiuoride, boron trifiuoride, aluminum tribromide, potassium ethoxide, sodium methoxide, calcium phenate, sodium hydroxide, calcium oxide, benzene sulfonic acid, toluene sulfonic acid, etc. A small amount such as 0.001% by weight of the catalyst often is sufiicient to promote esterification of the process of this invention. The amount of the catalyst may range up to about 1% by Weight of the process mixture.

It will be appreciated that when a succinic acid ester or a phosphorus acid ester is to react with a polyhydroxy reactant, the reaction is trans-esterification, i.e., the replacement of an ester radical derived from the polyhydroxy reactant for the ester radical originally present in the succinic or phosphorus acid ester reactant. For instance, where a di-methyl ester of a succinic acid is used in reaction with a partially esterified glycerol formed by the reaction of glycerol with phosphorus pentoxide, the product of this invention is formed by trans-esterification wherein one or both of the methyl radicals of the succinic reactant are replaced with radicals derived from the partially esterified glycerol intermediate and methanol is the by-product. When triphenyl phenyl phosphite is used in reaction with a partially esterified glycerol formed by the reaction of glycerol and a polyisobutene-substituted succinic acid, the product of this invention is formed by transesterification wherein one or more of the phenyl radicals of triphenyl phosphite are replaced with the ester radicals derived from the partially esterified glycerol intermediate and phenol is the by-product. The latter may involve trans-esterification reactions including, e.g., the one illustrated as follows:

wherein R is a substantially hydrocarbon radical. The above phosphorus-containing ester may react further with the partially esterified glycerol to form more complex products such as polymeric substances. Similarly, the use of a succinic halide (such as a polyisobutene-substituted succinic acid dichloride) or a phosphorus acid halide (such as phosphorus pentoxide or phosphorus trichloride) with a partially esterified polyhydroxy intermediate results in replacing the halide radical of the reactant with an ester radical derived from the partially esterified polyhydroxy intermediate. For instance, the reaction of a succinic dichloride with ethylene glycol and phosphorus pentoxide may proceed as follows:

The following examples illustrate the process of this invention.

EXAMPLE 1 A partially esterified pentaerythritol is prepared by adding 136 parts (by weight, 1 molar proportion) of pentaerythritol to a mixture of 1130 parts (1 molar proportion) of a polyisobutene-substituted succinic anhydride having an acid number of 99 (prepared by heating a chlorinated polyisobutene having a molecular weight of 900 and a chlorine content of 4.4% with 20% molar excess of maleic anhydride at 205 C.) and 830 parts of a mineral oil and heating the resulting mixture at C. for 5 hours and at 200-210 C. for 5 hours and filtering the product. The by-product (water) is distilled off during the heating. The filtrate is a 40% oil solution of the partially esterified ester intermediate. To 1020 parts of this filtrate, there is added 310 parts (0.5 molar proportion for each, molar proportion of the pentaerythritol used) of triphenyl phosphite. The mixture is heated at 180-190 C. for 10 hours and then at 180 C./20 mm. whereupon 96 parts of phenol is distilled off as the byproduct of trans-esterification. The filtrate is a 33% oil solution of the phosphorus-containing ester having a phosphorus content of 2.5%.

EXAMPLE 2 propylene glycol is prepared by adding dropwise propylene oxide to the above succinic acid (0.5 mole per mole of propylene oxide) at 80110 C., heating the resulting mixture to 100 C./7 mm., mixing the residue with an additional quantity of mineral oil to prepare a 50% oil solution and then filtering the oil solution. A mixture of 1733 parts of the above oil solution of the partially esterified propylene glycol and 91 parts of triphenylphosphite is heated at 150160 C. for 7.5 hours whereupon phenol (57 parts) is distilled off. The residue is diluted with mineral oil to form a 50% oil solution and filtered. The filtrate is an oil solution of a phosphorus-containing ester having a phosphorus content of 0.5%.

EXAMPLE 3 The oil solution (1890 parts) of the partially esterified propylene glycol of Example 2 and phosphorus pentoxide (46 parts) are mixed at 23 C. The mixture is heated at 5060 C. for 7 /2 hours and then to 60 C./ mm. The mixture is filtered. The filtrate is an oil solution of a phosphorus-containing ester.

EXAMPLE 4 A mixture of 670 parts of pentaerythritol and 2670 parts of the polyisobutene-substituted succinic anhydride of Example 1 (0.5 mole per mole of pentaerythritol) in 2194 parts of mineral oil is heated to 190 C. in 3 hours and then at 190200 C. for 8 hours. The mixture is blown with nitrogen for 0.5 hour and filtered. The filtrate is a 40% oil solution of a partially esterified pentaerythritol. To 2935 parts of the above solution and 1060 parts of mineral oil there is added 284 parts of phosphorus pentoxide (0.8 molar proportions for each molar proportion of the pentaerythritol used). The resulting mixture is heated at 115l20 C. for 5 hours and filtered. The filtrate is a oil solution of a phosphorus-containing ester having a phosphorus content of 1.2%.

EXAMPLE 5 A mixture of 1 mole of ethylene glycol, 0.5 mole of phophorus pentoxide, and 0.5 mole of a polyisobutene (molecular weight of 60,000)-substituted succinic anhydride (having an acid number of 100 and prepared by the reaction of maleic anhydride and a chlorinated polyisobutene having a molecular weight of 60,000 and a chlorine content of 4.3% at 205 C.) in three times its volume of a mineral oil is prepared at C. and then heated at 120140 C. for 10 hours.

EXAMPLE 6 EXAMPLE 7 A mixture of 1 mole of the polyisobutene-substituted succinic anhydride of Example 1 and 1 mole of glycerol in twice the volume of the mixture of toluene is heated at the reflux temperature (100 C.) while water is removed by azeotropic distillation. To the residue there is added 0.5 mole of phosphorus pentasulfide and the resulting mixture is heated at 90110 C. for 4 hours. Toluene is then removed by vacuum distillation. The residue is a phosphorus-containing ester.

EXAMPLE 8 A partially esterified propylene glycol is obtained by reacting 1 mole of phosphoric acid with 3.3 moles of propylene oxide while the by-product (water) is distilled 12; 01f. To 390 grams of this partially esterified propylene glycol there is added 200 grams of toluene and 1495 grams of the polyisobutene-substituted succinic anhydride of Example 1. The mixture is heated at 158163 C. for 8 hours and then at 160 C./1-2 mm. The residue is mixed with 1200 grams of mineral oil and heated to distill otf toluene. The residue is filtered. The filtrate is an oil solution of a phosphorus-containing ester having a phophorus content of 7.7%.

EXAMPLE 9 A partially esterified sorbitol is prepared by heating at 110-150 C. 1 mole of sorbitol and 1 mole of phosphorus pentoxide. The intermediate is dissolved in white oil and mixed with 2.5 moles of the polyisobutene-substituted succinic anhydride of Example 1. The resulting mixture is heated at 200 C. for 7 hours and filtered.

EXAMPLE 10 An olefin polymer-substituted succinic anhydride is obtained by heating 1.2 moles of maleic anhydride with 1 mole of a copolymer of mole percent of propylene and 25 mole percent of ethylene having an average molecular weight of 10,000 at 200-220 C. To a solution of the above anhydride in an equal weight of mineral oil, there is added at 25 C. 2 moles of neopentyl glycol and 1 mole of phosphorus acid. The mixture is heated to 120 C. for 2 hours and then at 120-180 C. for 5 hours whereupon water is removed by distillation. The residue is filtered. The filtrate is an oil solution of the phosphoruscontaining ester.

EXAMPLE 11 A phosphorus-containing ester is prepared by the procedure of Example 10 from a reaction mixture of 0.1 mole of an isobutene-styrene copolymer (:5 by weight of isobutene to styrene, average molecular weight of 2000)-substituted succinic anhydride, 1 mole of di(ethylene glycol and 0.5 mole of phosphoric oxychloride.

EXAMPLE 12 A phosphorus-containing ester is obtained by the procedure of Example 10 from a reaction mixture of 0.5 mole of the polyisobutene-substituted succinic anhydride of Example 1, 1 mole of tri(ethylene glycol), and 0.1 mole of dimethyl phosphite.

EXAMPLE 13 A phosphorus-containing ester is obtained by the procedure of Example 10 from a reaction mixture of 1 mole of the polyisobutene-substituted succinic anhydride of Example 1, 0.5 mole of triethyl phosphite, and 1 mole of a copolymer of 5 moles of allyl alcohol and 1 mole of styrene having a molecular weight of 1100.

EXAMPLE 14 A phosphorus-containing ester is obtained by heating at 150-180 C. a mixture of the partially esterified pentaerythritol (40% oil solution) and diphenylphosphorothioic chloride (2 moles per mole of pentaerythritol).

EXAMPLE 15 A phosphorus-containing ester is obtained by first heating at 120-200 C. 1 mole of the polyisobutene-substituted succinic anhydride of Example 1 and 1 mole of mannitol monooleate to form a partially esterified mannitol intermediate and then heating at 200 C. the intermediate with 3 moles of di(heptylphenyl)phosphorus chloride (i.e., (C H C H O) PCl) in an equal volume of mineral oil.

EXAMPLE 16 A phosphorus-containing ester is obtained by first heating at -180 C. 1 mole of the polyisobutene-substituted succinic anhydride of Example 1 and 1 mole of glycerol in 1000 grams of mineral oil and then heating 13 at 150-200' C. the above reaction mixture with 0.5 mole of the anhydride of diethylphosphoric acid (i.e.,

EXAMPLE 17 EXAMPLE 18 A phosphorus-containing ester is prepared as follows: a partially esterified resorcinol (formed by heating at 100200 C. 0.75 mole of the polyisobutene-substituted succinic anhydride of Example 1 with 1 mole of resorcinol in 1000 grams of diphenyl ether as the diluent) and phosphorus pentoxide (0.1 mole per mole of resorcinol) areheated at 150160 C. for hours.

EXAMPLE 19 A phosphorus-containing ester is obtained by the procedure of Example 18 except that resorcinol is replaced on a molar basis with 4-heptyl-1,2-dihydroxybenzene.

EXAMPLE 20 A phosphorus-containing ester is obtained by the procedure of Example 18 except that resorcinol is replaced on a molar basis with 1,2-dihydroxynaphthylene.

The phosphorus-containing esters of this invention are useful for a wide variety of purposes including pesticides, plasticizers, rust-inhibiting agents for treatment of metals, corrosion-inhibiting agents, extreme pressure agents, antiwear agents, and detergents.

A principal utility of such products is as additives in lubricants. It has been discovered in accordance with this invention that when used for such purpose their effectiveness to impart a specific property to a lubricant is closely related to the size of the hydrocarbon substituent in the hydrocarbon-substituted succinic acid-producing compounds from which the phosphorus-containing esters are derived. More particularly it has been found that products in which the substantially hydrocarbon substituent contains more than about 50 aliphatic carbon atoms are particularly effective for the purposes of this invention.

The lubricating oils in which the substituted polyamines 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-Z-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 phosphorous-containing esters as additives in lubricants usually ranges from about 0.01% to about by weight. The optimum concentrations for a particular application depend to a large measure upon the type of service to which the lubricant is to be subjected. Thus, for example, lubricants for use in gasoline internal combustion engines may contain from about 0.5 to about 10% of the additive, whereas lubricating compositions for use in gears and diesel engines may contain as much as or even more of the additive. Lubricants for use in the oil-fuel mixture for two-stroke engines may contain from about 1% to 10% 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 promoters include phenolic substances such as phenol, naphthol, alkylphenol, triophenol, 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 cyclohexyl alcohol; amines such as aniline, phenylenediamine, phenothiazine, phenyl beta-naphthylamine, 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 60-200 C.

The preparation of a basic sulfonate detergent is illustrated as follows: A mixture of 490 parts (by weight) of a mineral oil, parts of water, 61 parts of heptylphenol, 340 parts of barium mahogany sulfonate, and 227 parts of barium oxide is heated at 100 C. for 0.5 hour and then to C. Carbon dioxide is then bubbled into the mixture until the mixture is substantially neutral. The mixture is filtered and the filtrate found to have a sulfate ash content of 25%.

The preparation of a basic barium salt of a phosphorus acid is illustrated as follows: A polyisbutene having a molecular weight of 50,000 is mixed with 10% by weight of phosphorus pentasulfide at 200 C. for 6 hours. The resulting product is hydrolyzed by treatment'with steam at C. to produce an acidic intermediate. The acidic intermediate is then converted to a basic salt by mixing twice its volume of mineral oil, 2 moles of barium hydroxide and 0.7 mole of phenol and carbonating the mixture at 150 C. to produce a fluid product,

The phosphorus-containing esters are especially adapted for use in combination with extreme pressure and corrosion-inhibiting 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 phosphorus-containing 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.

15 The Group II metal phosphorodithioates are the salts of acids having the formula R SH in which R and R are substantially hydrocarbon radicals. The metals for forming such salts are exemplified by bar ium, 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, sec-butyl, the various amyl alcohols, n-hexyl, methylisobutyl carbinyl, heptyl, 2-ethylhexyl, di' isobutyl, 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' The availability of the phosphorodithioic acids from which the Group II metal salts of this invention are prepared is well known. They are prepared by the reaction of phosphorus pentasulfide with an alcohol or phenol. The reaction involves four moles of the alcohol or phenol per mole of phosphorus pentasulfide, and may be carried out within the temperature range from about 50 C. to about 200 C. Thus the preparation of 0,0-di-n-hexyl phosphorodithioic acid involves the reaction of phosphorus pentasulfide with four moles of n-hexyl alcohol at about 100 C. for about 2 hours. Hydrogen sulfide is liberated and the residue is the defined acid. The preparation of the zinc or barium salt of this acid may be effected by reaction with zinc oxide or barium oxide. Simply mixing and heating these two reactants is sufficient to cause the reaction to take place and the resulting product is sufiiciently pure for the purpose of this invention.

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 axide or barium oxide to produce less expensive, oil-soluble salts.

Another class of the phosphorothioate additives contemplated for use in the lubricating composition 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-betanaphthyl-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. Examples of such lower alkylene oxides are ethylene oxide, propylene oxide, 1,2-butene oxide, trimethylene oxide, tetramethylene oxide, butadiene monoepoxide, 1,2-hexene oxide, and propylene epichlorohydrin. Other epoxides useful herein include, for example, butyl 9,10-epoxy-stearate, ep-

16 oxidzed soya bean oil, epoxidized tung oil, and epoxidized copolymer of styrene with butadiene.

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 ot about 1 mole of a lower alkylene oxide, particularly ethylene oxide and propylene oxide, have been found to b especially useful and therefore are preferred.

The lubricating compositions may contain metal detergent additives in amounts usually within the range of about 0.1% to about 20% by weight. In some applications such as in lubricating marine diesel engines the lubircating compositions may contain as much as 30% of a metal detergent additive. They may contain other additives such as extreme pressure addition agents, viscosity index improving agents, and pour point depressing agents, each in amounts withint he 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 I SAE 20 mineral lubricating oil containing 0.5% of the product of Example 1.

EXAMPLE II 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 III SAE l0W30 mineral lubricating oil containing 0.4% of the product of Example 3.

EXAMPLE IV SAE mineral lubricating oil containing 0.1% of the product of Example 4 and 0.15% of the zinc salt of an equimolar mixture of di-cyclohexylphosphorodithioic acid and di-isobutyl phosphorodithioic acid.

EXAMPLE V SAE 30 mineral lubricating oil containing 2% of the product of Example 4.

EXAMPLE VI SAE 20W-30 mineral lubricating oil containing 5% of the product of Example 5.

EXAMPLE VII SAE 10W-30 mineral lubricating oil containing 1.5% of the product of Example 2 and 0.05% of phosphorus as the zinc salt of a 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 n-pentyl alcohol.

EXAMPLE VIII SAE 50 mineral lubricating oil containing 3% of the product of Example 4 and 0.1% of phosphorus as the calcium salt of di-hexylphosphorodithioate.

1 7 EXAMPLE IX SAE 10W30 mineral lubricating oil containing 2% of the product of Example 2, 0.06% of phosphorus as zinc di-n-octylphosphorodithioate, and 1% of sulfate ash as barium mahogany sulfonate.

EXAMPLE X SAE 30 mineral lubricating oil containing 5% of the product of Example 10, 0.1% of phosphorus as the zinc salt of a mixture of equimolar amounts of di-isopropylphosphorodithioic acid, and di-n-decylphosphorodithioic acid, and 2.5% of sulfate ash as a basic 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 XI SAE W-30 mineral lubricating oil containing 6% of the product of Example 17, 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 XII SAE 10 mineral lubricating oil containing 2% of the product of Example 20, 0.075% of phosphorus as the adduct of zinc di-cyclohexylphosphorodithioate treated with 0.3 mole of ethylene oxide, 2% of a sulfurized sperm oil having a sulfur content of 10%, 3.5% of a poly-(alkyl methacrylate) viscosity index improver, 0.02% of a poly- (alkyl methacrylate) pour point depressant, 0.003% of a poly-(alkyl siloxane) anti-foam agent.

EXAMPLE XIII SAE 10 mineral lubricating oil containing 1.5% of the product of Example 19, 0.075% of phosphorus as the adduct obtained by heating zinc dinonylphosphorodithioate With 0.25 mole of 1,2-hexene oxide at 120 C., a sulfurized methyl ester of tall oil acid having a sulfur content of 6% of a polybutane viscosity index improver, 0.005% of a poly-(alkyl methacrylate) anti-foam agent, and 0.5% of lard oil.

EXAMPLE XIV SAE mineral lubricating oil containing 1.5% of the product of Example 2, 0.5% of di-dodecyl phosphite, 2% of the sulfurized sperm oil having a sulfur content of 9%, a basic calcium detergent prepared by carbonating a mixture comprising mineral oil, calcium mahogany sulfonate and 6 moles of calcium hydroxide in the presence of an equi-molar mixture (10% of the mixture) of methyl alcohol and n-butyl alcohol as the promoter at the reflux temperature.

EXAMPLE XV SAE 10 mineral lubricating oil containing of the product of Example 13, 0.07% of phosphorus as zinc dioctylphosphorodithioate, 2% of a barium detergent prepared by neutralizing with barium hydroxide the hydrolyzed reaction product of polypropylene (molecular weight 2000) with 1 mole of phosphorus pentasulfide and 1 mole of sulfur, 3% of a barium sulfonate detergent prepared by carbonating a mineral oil solution of mahogany acid, and 500% stoichiometrically excess amount of barium hydroxide in the presence of phenol as the promoter at 180 C., 3% of a supplemental ashless detergent prepared by copolymerizing a mixture of 95% (Weight) of decyl-methacrylate and 5% (weight) of diethylaminoethylacrylate.

EXAMPLE XVI SAE 80 mineral lubricating oil containing 2% of the product of Example 20, 0.1% of phosphorus as zinc di- 18 n-hexylphosphorodithioate, 10% of a chlorinated paraffin wax having a chlorine content of 40%, 2% of di-butyl tetrasulfide, 2% of sulfurized dipentene, 0.2% of oleyl amide, 0.003% of an anti-foam agent, 0.02% of a pour point depressant, and 3% of a viscosity index improver.

EXAMPLE XVII SAE 10 mineral lubricating oil containing 3% of the product of Example 3, 0.075% of phosphorus as the zinc salt of a phosphorodithioic acid prepared by the reaction of phosphorus pentasulfide with an equimolar 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.

EXAMPLE XVIII SAE 20 mineral lubricating oil containing 2% of the product of Example 12 and 0.07% of phosphorus as zinc di-n-octylphosphorodithioate.

EXAMPLE XIX SAE 30 mineral lubricating oil containing 3% of the product of Example 14 and 0.1% of phosphorus as zinc di-(isobutylphenyl)-phosphorodithioate.

EXAMPLE XX SAE 50 mineral lubricating oil containing 2% of the product of Example 9.

EXAMPLE XXI SAE mineral lubricating oil containing 3% of the product of Example 11 and 0.2% of phosphorus as the reaction product of 4 moles of turpentine with 1 mole of phosphorus pentasulfide.

EXAMPLE XXII SAE 90 mineral lubricating oil containing 3% of the product of Example 12 and 0.2% of 4,4-methylenebis- (2,6-di-tert-butylphenol) EXAMPLE XXIII SAE 30 mineral lubricating oil containing 2% of the product of Example 13 and 0.1% of phosphorus as phenylethyl di-cyclohexylphosphorodithioate.

EXAMPLE XXIV SAE 90 mineral lubricating oil containing 5% of the product of Example 1 and 1% of the calcium salt of the sulfurized phenol obtained by the reaction of 2 moles of heptylphenol with 1 mole of sulfur.

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

The utility of the phosphorus-containing esters of this invention as additives in lubricating compositions is illustrated by the results from an oxidation and detergency test in which a 350 cc. sample of a lubricant containing 0.001% of iron napthenate and 1.5 by Weight of the solvent-free additive to be tested is placed in a 2 x 15 (inches) borosilicate tube. A 1 /8 x 5% (inches) SAE 1020 steel panel is immersed in the test oil. The sample then is heated at 300 F. for a specified period while air is bubbled through it at the rate of 10 liters per hour. The oxidized sample is cooled to F., homogenized with 0.5 of water allowed to stand at room temperature for 24 hours, and then filtered through two layers of No. 1 Whatman filter paper at 20 MM. Hg pressure. The weight of the precipitate, washed with naptha and dried, is taken as a measure of the efiectiveness of the additive to inhibit oxidation and disperse the sludge formed during the test. The greater the weight of the precipitate the less effective the additive. The results of the test are indicated in the following Table I. The base oil of the lubricant sample employed in the test is a Mid-Continent, conventionally refined mineral oil having a viscosity of about 200 Saybolt Universal seconds at 100 F.

TAB LE I Test result, milligrams of sludge per 100 ml. of lubricant Hours of test The efficacy of the substituted polyamines of this invention as detergent additives in lubricants for diesel engines operated under relatively severe conditions is demonstrated by the results (Table II) of the CRC-L-l Engine test (also known as Caterpillar 1E test). In this test, the lubricating composition is used in the crankcase of a 4- stroke diesel engine having a compression ration of 15:1 operated for 120 hours under the following conditions: speed 100 r.p.m.; B.t.u. input per minute, 2900-3000; load, 20 brake horsepower; water jacket temperature, 175180 F.; oil temperature, l40l50 F. A diesel fuel having a sulfur content of either 1% or 0.4% is used. The lubricant is evaluated according to (1) the piston cleanliness (rating scale of 100, 100 being indicative of no deposit and being indicative of heavy deposits) and (2) the amount of ring filling.

TABLE II Percent Piston Lubricant tested ring cleanliness filling rating (G) SAE 30 mineral lubricating oil containing 1.68% of the product of Example 1 1 97.0

wherein R is a hydrocarbon radical, a polar-substituted hydrocarbon radical having up to about 10% by weight of at least one polar substituent, or an ether-containing hydrocarbon radical and x is an integer greater than one with from about 0.5 to x moles of an acid-producing mixture of (A) a succinic acid-producing compound selected from the class consisting of hydrocarbon-substituted succinic acids and the halides, the esters having up to about 18 aliphatic carbon atoms, and the anhydrides thereof having at least about 50 aliphatic carbon atoms in the hydrocarbon substituent and (B) a phosphorus acid-producing compound selected from the class consisting of phosphoric acids, phosphorous acids, and the halides, the esters having up to about 30 aliphatic carbon atoms, and the anhydrides thereof, the molar ratio of said succinic acid-producing compound to said phosphorus acid-producing compound being within the range of from about 0.1:1 to 10:1.

2. A lubricating composition comprising a major proportion of a lubricating oil and a minor proportion, sufficient to improve detergency and oxidation stability, of a phosphorus containing ester prepared by the process comprising the reaction of one mole of a polyhydric alcohol having up to about 8 hydroxy radicals with from about 0.5 to 8 moles of an acid-producing mixture of (A) an olefin polymer-substituted succinic anhydride in which the olefin polymer substituent has a molecular weight of from about 750 to 5000 and (B) a trihydrocarbon phosphite having up to about 30 carbon atoms in each hydrocarbon radical, the molar ratio of said succinic anhydride 20 to said phosphite being within the range of from about 0.1:1 to 10:1.

3. The lubricating composition of claim 2 characterized further in that the polyhydric alcohol has from 3 to 6 hydroxy radicals.

4. The lubricating composition of claim 2 characterized further in that the trihydrocarbon phosphite is triphenyl phosphite.

5. A lubricating composition comprising a major proportion of a lubricating oil and a minor proportion, sufficient to improve detergency and oxidation stability, of a phosphorus containing ester prepared by the process comprising the reaction at a temperature above about C. of one mole of a polyhydric alcohol having from about 3 to 6 hydroxy radicals with from about 0.5 to 3 moles of an acid-producing mixture of (A) a polyisobutene-substituted succinic anhydride in which the polyisobutene substituent has a molecular weight of from about 750 to 5000 and (B) a triaryl phosphite, the molar ratio of said succinic anhydride to said phosphite being within the range of from about 0.121 to 10:1.

6. The lubricating composition of claim 1 characterized further in that the polyhydroxy compound is a poly (oxyalkylene) glycol.

7. A lubricating composition comprising a major proportion of a lubricating oil and a minor proportion, sufiicient to improve detergency and oxidation stability, of a phosphorus containing ester prepared by the process comprising forming a partially esterified intermediate by the reaction at a temperature above about 100 C. of a polyhydroxy compound having the formula wherein R is a hydrocarbon radical, poly-substituted hydrocarbon radical having up to about 10% by weight of at least one polar substituent, or an ether-containing hydrocarbon radical and x is an integer greater than one with a succinic acid-producing compound selected from the class consisting of hydrocarbon-substituted succinic acids and the halides, the esters having up to about 18 aliphatic carbon atoms, and the anhydrides thereof having at least about 50 aliphatic carbon atoms in the hydrocarbon substituent and reacting at a temperature above about 100 C. said intermediate with a phosphorus acid-producing compound selected from the class consisting of phosphoric acids, phosphorous acids, and the halides, the esters having up to about 30 aliphatic carbon atoms, and the anhydrides thereof, the total amount of said succinic acid producing compound and said phosphorus acid-producing compound being equal to from about 0.5 to x moles per mole of the polyhydroxy compound and the molar ratio of said succinic acid-producing compound to said phosphorus acid-producing compound being within the range of from about 0.1:1 to 10:1.

8. A lubricating composition comprising a major proportion of a lubricating oil and a minor proportion, sufiicient to improve detergency and oxidation stability, of a phosphorus containing ester prepared by the process com prising forming a partially esterified ester by the reaction at a temperature above about 100 C. of a polyhydric alcohol having from about 3 to 6 hydroxy radicals with an olefin polymer-substituted succinic anhydride in which the olefin polymer substituent has a molecular weight of from about 750 to 5000 and reacting at a temperature above about 100 C. said intermediate with a triaryl phosphite, the total amounts of said succinic anhydride and said phosphite being from about 0.5 to 3 moles per mole of the polyhydric alcohol and the molar ratio of said succinic anhydride to said phosphite being within the range of from about 0.1 :l to 10:1.

9. The lubricating composition of claim 8 characterized further in that the polyhydric alcohol has four hydroxy radicals.

10. The lubricating composition of claim 8 characterized further in that the olefin polymer-substituted succinic.

21 anhydride is a polyisobutene-substituted succinic anhydride.

11. The lubricating composition of claim 8 characterized further in that the triaryl phosphite is triphenyl phosphite.

12. A lubricating composition comprising a major proportion of a lubricating oil and a minor proportion, suflicient to improve detergency and oxidation stability, of a phosphorus containing ester prepared by the process comprising forming a partially esterified intermediate by the reaction at a temperature above about 100 C. 1 mole of a tetrahydric alcohol having from about 4 to 12 carbon atoms with from about 0.5 to 1.5 moles of a polyisobutene-substituted succinic anhydride in which the polyisobutene substituent has a molecular weight of from about 750 to 5000 and reacting said intermediate at a temperature above about 100 C. from about 0.1 to 1 mole of a triaryl phosphite.

13. The lubricating composition of claim 12 characterized further in that the tetrahydric alcohol is pentaerythritol.

14. The lubricating composition of claim 12 characterized further in that the triaryl phosphite is triphenyl phosphite.

References Cited UNITED STATES PATENTS 3,255,108 6/1966 Wiese 25256 XR 3,202,693 8/1965 Gaetner 4470 XR 3,288,714 11/1966 Osuch 252-56 DANIEL E. WYMAN, Primary Examiner.

W. H. CANNON, Assistant Examiner.

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