US3778370A

US3778370A - Lubricating oil additives and compositions containing such additives

Info

Publication number: US3778370A
Application number: US00199034A
Authority: US
Inventors: B Kennedy; Vries L De
Original assignee: Chevron Research and Technology Co
Current assignee: Chevron USA Inc
Priority date: 1971-11-15
Filing date: 1971-11-15
Publication date: 1973-12-11
Anticipated expiration: 1990-12-11
Also published as: JPS4859103A; JPS5347123B2; DE2252076A1; FR2165867A1; GB1367012A; IT970442B; FR2165867B1

Abstract

ESTERS OF 4-HYDROXY- AND 4-THIOL-BENZOIC ACIDS, DITHIO, 1,4-DIHYDRO-1-OXO-4-DITHIOMETHYLENEBENZENES AND 1,4DIHYDRO-1-OXO-4- (DITHIACYCLOPENT-2-YLIDENE)-BENZENES IN WHICH THE HYDROXY, THIOL AND OXO GROUPS ARE STERICALLY HINDERED ARE PROVIDED. ALSO PROVIDED ARE INTERMEDIATES FOR SUCH ESTERS AND SUBSTITUTED BENZENES. IN ADDITION, PROCESSES ARE PROVIDED FOR PREPARING THESE INTERMEDIATES FOR SUCH COMPOUNDS AND PROCESSES FOR PREPARING SUCH COMPOUNDS. THESE COMPOUNDS ARE MIXTURES THEREOF ARE USEFUL AS ADDITIVES FOR LUBRICATING OILS PROVIDING SUCH OILS WITH HIGH RESISTANCE TO OXIDATIVE CHANGE. IN ADDITION, OILS CONTAINING CERTAIN OF THE ESTERS, PARTICULAR BIS-ALKYLENE ESTERS, AND CERTAIN OF THE DITHIACYCLOPENTYLIDENE BENZENES AND MIXTURES THEREOF DEMONSTRATES SUPERIOR EXTREME PRESSURE LUBRICATING PROPERTIES.

Description

United States Patent Oflice 3,778,370 Patented Dec. 11, 1973 ABSTRACT OF THE DISCLOSURE Esters of 4-hydroxyand 4 thiol-benzoic acids, dithio, 1,4-dihydro-1-oxo-4-dithiomethylenebenzenes and 1,4- dihydro-1-oxo-4-(dithiacyclopent-Z-ylidene)-benzenes in which the hydroxy, thiol and oxo groups are sterically hindered are provided. Also provided are intermediates for such esters and substituted benzenes. In addition,

I processes are provided for preparing these intermediates for such compounds and processes for preparing such compounds. These compounds and mixtures thereof are useful as additives for lubricating oils providing such oils with high resistance to oxidative change. In addition, oils containing certain of the esters, particular bis-alkylene esters, and certain of the dithiacyclopentylidene benzenes and mixtures thereof demonstrate superior extreme pressure lubricating properties.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to compounds useful as additives for lubricating oil compositions, to intermediates for such compounds, to processes for preparing these compounds, and to lubricating oil compositions containing such compounds. Lubricating oils are employed in a host of environments. Under most conditions of use, the oil comes into contact with air, often at elevated temperatures and in the presence of metals or chemical compounds which act as oxidation catalysts. Lubricating oils, whether natural or synthetic, when exposed to such conditions, undergo a series of oxidation reactions. The deleterious efiects of such oxidation includes an increase in viscosity, formation of carbonaceous matter and the production of various oxygen-containing contaminants. Among others, the contaminants have been found to include lactones, ketones, aldehydes, esters, alcohols, hydroxy acids, anhydrides, and peroxides. The acidic and peroxidic contaminants attack metals, corrode bearings, and promote rust and wear. Acidic contaminants are also a major source of the oil insolubles that cause ring sticking and sludging, and impede oil flow. Antioxidants are incorporated in lubricating oils to retard such oxidation of the oil.

As, the pressures or rubbing speeds between relatively moving surfaces increase, the film of oil normally present between the surfaces is squeezed out or wiped away. When this occurs, hydrodynamic lubrication ceases and boundary lubrication occurs. During boundary lubrication, metal-to-metal contact is experienced over a significant portion of the lubricated area. This contact often leads to excessive wear or destruction of the relatively moving surfaces. Extreme pressure additives are incorported in lubricating compositions to aid in the lubrication of moving metal surfaces under boundary lubrication conditions.

DESCRIPTION OF THE PRIOR ART Stevens et al., US. Pat. 2,265,582, issued Dec. 9, 1941, discloses tri-alkylated monohydroxy phenols having, in the positions ortho to the hydroxy group, at least one alkyl group containing three or more carbon atoms.

These phenols known as hindered phenols are said to inhibit oxidational changes in petroleum hydrocarbon products, when incorporated therein in small amounts.

Humphreys et al., US. Pat. 2,073,841, issued Mar. 16, 1937, describes extreme pressure lubricating compositions containing esters and anhydrides of organic thio acids. Useful compounds are said to include s-ethyl thiobenzoate and benyl thiobenzoate.

Gompper and Toppl, Substituierte Dithiocarbonsauren and Ketenmercaptale, Berichte, 19 62, 95, 2861 disclose the reaction of active methylene compounds such as cyanoacetamide with carbon disulfide followed by reaction with various halides to produce various dithio derivatives.

Andress, Jr., et al. US. Pat. 3,609,081, describes organic compositions such as lubricating oils and fuel oils containing secondary trialkyl phenols in which the secondary alkyl groups contain from 6 to 9 carbon atoms. The phenols are described as antioxidants for the organic compositions.

SUMMARY OF THE INVENTION The compounds of this invention comprise esters of 4-hydroxy and 4-thiol benzoic acids, dithio; 1,4dihydrol-oxo-4-dithiomethylenebenzenes and 1,4-dihydro-l-oxo- 4-(1,3-dithiacyclopent-Z-ylidene)benzenes having nuclear alkyl substituents in both positions ortho to the hydroxy, thiol, and oxo groups which sterically hinder these groups.

These compounds are useful as additives for lubricating oil compositions. The presence of these additives provides antioxidation protection for the oil and, in many cases, additionally confers extreme pressure lubricating properties to the oil.

DESCRIPTION OF THE INVENTION In a first embodiment novel esters of 4-hydroxy and 4-thiol benzoic acids, diothio, novel 1,4-dihydro-1-oxo- 4-dithiomethylenebenzenes and novel 1,4-dihydro-l-oxo- 4-(1,3-dithiacyclopent-Z-ylidene)benzenes having nuclear alkyl substituents in both positions ortho to the hydroxy, thiol and oxo groups which sterically hinder these groups are provided.

The esters and substituted benzenes of this invention are derived from 4-hydroxy and 4-thiol benzoic acids, dithio. The benzoic acid moiety is substituted in both positions ortho to the hydroxy and thiol groups with alkyl substituents which sterically hinder the hydroxy and thiol groups. Such alkyl substituents have four or more carbon atoms and are generally branched rather than straight chain, e.g., t-butyl, t-amyl and the like.

Preferred compounds of the invention include esters of 4-hydroxy and 4-thiol benzoic acids, dithio having the following formulae:

( i tY 1,4-dihydro-1-oxo-4-dithiomethylenebenzenes having the following formula:

and 1,4 dihydro-1-oxo-4- (1,3-dithiacyc1opent-2-ylidene) benzenes having the following formula:

In the above Formulae I, II, III, and IV:

(1) R and R each represent an alkyl group, which sterically hinders the adjacent hydroxy, thiol, or x0 group, containing four or more carbon atoms, desirably four to nine carbon atoms in a branched chain, such as t-butyl, t-amyl, s-hexyl, s-heptyl, s-octyl, s-nonyl and the like;

(2) R R and R each represent alkyl containing from 1 to 20 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, iso-amyl, tert-amyl, hexyl, heptyl, octyl, nonyl, dccyl, dodecyl, pentadecyl, eicosyl and the like; hydroxyalkyl, e.g., --R-OH, hydroxyalkyloxyalkyl, e.g.,

in which the alkylene moieties represented by R contain 2 to 5 carbon atoms and can be straight or branched chain such as ethylene, 1,2-propylene, 1,2-butylene, 1,2-pentylene and the like and n represent 2 to 6; aralkyl such as benzyl, p-xylyl, and the like; or aryl such as phenyl, 4-tolyl and the like;

(3) R represents an alkylene group containing from 1 to 8 carbon atoms such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, and the like;

(4) Each R represents hydrogen, alkyl such as defined above for R or aryl such as phenyl, tolyl, xylyl and the like, and preferably R represents hydrogen;

(5) X represents oxygen or sulfur and preferably oxygen; and

(6) Y represents hydrogen or a metallic cation such as those derived from alkali metal such as sodium and potassium and those derived from alkali earth metals such as calcium and barium; preferably Y represents hydrogen.

4 TABLE A Illustrative of the esters of benzoic acid, dithio contemplated by the invention are the following typical compounds:

Illustrative of the methylenebenzenes contemplated by the invention are the following typical compounds:

(XII) 1,4-dihydro-l-oxo-2,6-di-t-butyl-4-dimethylthiomethylenebenzene (XHI) 1,4-dihydro-1-thione-2,6-di-t-butyl-4-dimethylthiomethylenebenzene (XIV) l,4-dihydro-l-oxo-2,6-di-t-butyl-4-di-n-octylthiomethylenebenzene (XV) 1,4-dihydro-1-oxo-2,6-di-t-amyl-4-di-hydroxypropylenethiomethylenebenzene (XVI) 1,4-dihydro-1-oxo-2,6-di-t-butyl-4-di-hydroxypropylenethiomethylenebenzene Illustrative of the dithiacyclopent-ylidenebenzene contemplated by the invention are the following typical compounds:

(XVII) l,4-dihydro-1-oxo-2,6-di-t-butyl-4-(1,3-dithiacyclopent-2-ylidene) -benzene (XVIII) 1,4-dihydro-1-oxo-2,6-di-t-butyl-4-(4-methyl- 1,3-dithiacyclopent-2-ylidene)-benzene (XIX) 1,4-dihydro-1-oxo-2,6-di-t-amy1-4-(1,3-dithiacyclopent-Z-ylidene)benzene In a second embodiment of this invention intermediates for the above dithiobenzoic acid esters and substituted benzenes are provided which comprise 4-thiol and 4-hydroxybenzoic acids, dithio, in which the acids have nuclear alkyl substituents in both positions ortho to the hydroxy and thiol groups which sterically hinder such hydroxy and thiol groups.

Preferred intermediates of this invention include 4-thiol and 4-hydroxybenzoic acids having the following formula:

( JIIY s SY wherein X, Y, R and R have the same meaning as defined above.

In a third embodiment of this invention, processes are provided for preparing the above-described 4-thiol and 4-hydroxybenzoic acid, dithio, intermediates which comprise combining about one equivalent of a phenol or thiophenol having nuclear alkyl substituents in both positions ortho to the hydroxy or thiol group which sterically hinder the hydroxy or thiol group with about two ventiom r equivalents of a strong proton acceptor to obtain a first reaction product. This first product is then combined with about one equivalent of carbon disulfide to yield the intermediate as a dithiobenzoic acid radical.

This acid radical is probably in the form of the double salt of the cation of the proton acceptor. The dithiobenzoic acid can be recovered, if desired, by acidifying the reaction mixture with at least two equivalents of a proton donor such as a mineral acid to yield the dithiobenzoic acid in free acid form. However, it is generally more convenient to simply use the acid in its radical form without recovery from the reaction mixture as the intermediate for preparing the compounds of this in- As used herein and in the appended claims, the term strong proton acceptor refers to a moiety capable of extracting a proton from the para position of the sterically hindered phenols and thiophenols used to prepare the intermediates described above and shown in Formula V. Such proton acceptors are well known and include alkali metal hydroxides such as sodium and potassium hydroxide, alkali metal alkoxides such as sodium and po' tassium methoxide and ethoxide and alkali metal amides such as sodium and potassium amide.

The above process is preferably carried out in a solvent medium under an inert atmosphere. The solvent can be any inert solvent which does not interfere with the desired reactions. The solvents can be polar as well as non-polar. Generally, mixtures of polar and non-polar solvents are used in order to obtain at least partial miscibility of the various reactants. For example, a mixture of water, dimethyl sulfoxide and pentane, hexane or heptane is conveniently used. The inert atmosphere can be any atmosphere which does not interfere with the reaction. It is most conveniently nitrogen.

The reactions are carried out at low to moderate temperatures, e.g., from about 0 C. to about 50 C. and preferably from about 10 C. to about 40 C.

In a fourth embodiment of this invention, processes are provided for preparing the esters of dithiobenzoic acid and the substituted benzenes described above and exemplified in Formulas I-IV. These processes comprise combining the dithiobenzoic acid intermediate described above in its radical form with zero to one equivalent of a proton donor to obtain a third reaction product. This third reaction product is then combined with a two to one-half equivalents of a precursor of the desired thio substituent.

The quantity of proton donor with which the intermediate radical is combined is determined by the product desired. If the product desired is of the diester type represented by Formula III above or the cyclopentylidenebenzene of Formula IV above, the intermediate is not reacted with the proton donor. This double salt is thereby free to react with two equivalents of the precursor of the thio substituents. The precursor has only one reactive site or one equivalent if it has two reactive sites. If the. product is of the mono ester of the type represented byFormulas I and 11 above, then the intermediate is combined with one equivalent of the proton donor. This product is then free to react with one equivalent of thio substituent precursor if such precursor has one reactive site or one-half equivalent if the precursor has two reactive sites as in the case of the dihaloalkanes from which the. compounds of Formula II are prepared. However, see the discussion below concerning when the precursor is a dihaloalkane wherein the halo substituents are on adjacent carbon atoms.

The term proton donor" as used herein and in the appended claims, refers to a moiety capable of donating a proton to the thiobenzoic acid radical. These proton donors are conveniently strong mineral acids such as hydrochloric acid, sulfuric acid and nitric acid.

The precursors of the thio substituent are alkanes, hydroxyalkanes, hydroxyalkyloxyalkanes, hydroxyalkyl poly (oxalkyl) oxyalkanes and aralkanes substituted with at least one moiety which causes them to be reactive toward the dithiobenzoic acid radical. Conveniently these substituents are halogen and preferably chlorine. The precursors are substituted with one halo group except for those precursors used to prepare the esters of Formula II and the dithiacyclopent-Z-ylidenebenzenes. The precursors for these two types of compounds contain two halo substituents. The process of adding the proton donor to the dithiobenzoic acid radical can be carried out at varying temperatures; however, room temperature is quite convenient.

The process of esterifying the dithiobenzoic acid radical with the thio substituent precursor can also be carried 7 out over a wide temperature range suitably ranging from about room temperature up to about 100 C. or greater. Preferably, the reaction is carried out by combining the dithiobenzoic acid radical and the thio substituent precursor at about room temperature and heating the reaction mixture with stirring to about 50 to about C.

The time required for the reaction to proceed to completion can vary widely depending upon temperatures, concentrations, etc. Typically, the reaction will proceed to completion within about one to five hours when carried out in preferred temperature range.

In the preparation of the his esters such as Compound X from dihaloalkanes having the halo substituents on adjacent carbon atoms, it has been found a large amount of the corresponding dithiacyclopent-Z-ylidenebenzene is formed.

Without desiring to be bound by such speculation, it might be postulated that the intermediate formed upon reaction of one equivalent of dihaloalkane with one equivalent of the benzoic acid, dithio, radical could react as follows:

As can readily be seen the possible products which could be formed are not limited to the two products shown above. Yet another product might be a carbon sulfur polymer type chain having the oxobenzene groups pendant therefrom. Other products can also be envisioned.

Of this multiplicity of possible products, only two have been identified, namely the two products from Reactions A and B above. The non-purified reaction product obtained as described below and exemplified by Example VII, when added to a lubricating oil as described below, results in a composition having quite superior extreme pressure lubricating properties as well as high resistance to oxidative change. However, when the product of Reaction B above is isolated and added to a lubricating oil, the composition does not have nearly as good extreme pressure lubricating properties as the composition prepared from the unpurified reaction product.

What this unpurified reaction product contains to cause the lubricating oils to which it is added to have the superior extreme pressure lubricating properties is unknown. Again without wishing to be bound by speculation, it might be the synergistic efiect of the combination the his ester (Reaction A above) and the dithiacyclopent- 2-ylidenebenzene (Reaction B above) or it might be an as yet unidentified third component or some combination of these possibilities.

In a fifth embodiment, lubricating oil compositions are provided comprising a major amount of an oil of lubricating viscosity and an effective amount of a compound selected from the class consisting of esters of 4-hydroxybenzoic acids, dithio; esters of 4-thiolbenzoic acids, dithio; 1,4-dihydro-1-oxo 4 dithiomethylenebenzenes and 1,4- dihydrol-oxo-4 (1,3-dithiacyclopent-2 y1idene)benzenes in which the esters and benzenes have nuclear alkyl substituents in both positions ortho to the hydroxy, thiol, or x0 groups which sterically hinder such groups. Preferably, the lubricating oil compositions of this invention comprise a major amount of an oil of lubricating viscosity and an effective amount of one or more of the compounds of Formulas IIV.

The esters and benzenes are present in the lubricating oil composition in an amount effective to impart the desired antioxidation and extreme pressure lubrication properties. This amount can range from about 0.1 percent weight to about percent weight of the total oil composition and generally from about 0.5 percent weight to about 3 percent weight of the total oil composition.

In general, solutions of the esters and benzenes in oil are more readily obtained when the groups represented by R R and R in the above formulae are oleophilic in nature, e.g., have medium length or longer alkyl chains such as octyl, decyl, dodecyl eicosyl, and the like or have a higher number of oxyalkyl units in the hydroxalkyl poly(oxyalkyl) chain.

It has been found that the hydroxyalkyl substituted compounds and higher homologs tend to be crystalline in nature.

In some instances, for example, where these compounds are used in higher concentrations, e.g., 2-5 percent weight of the total oil composition, they may be diflicult to dissolve in the oil and occasionally may crystallize out of the oil. These crystallinity problems generally are readily overcome by using a mixture of hydroxyalkyls having a varying number oxyalkyl units in the chain such as a mixture of esters having about one-half each of a hydroxyalkyloxyalkyl and a hydroxyalkyl-di-oxyalkyl substituent.

8 The esters and benzenes can be added to the oil singly or in mixtures. For example, a mixture of two or more esters can be used. Alternatively, a mixture of two or more benzenes or a mixture of esters and benzenes can be used. It may be noted that the benzenes are, in a sense, a double esterification product obtained from the synthesis of the ester. Often varying quantities of esters of benzenes are produced as impurities during the synthesis of the other type of compound. It is generally most convenient to simply use the mixture obtained without attempting a separation of the compounds.

OTHER ADDITIV ES Other additives may also be included in the oil composition to fulfill functions other than those provided by the esters and benzenes as well as to augment the functions of the latter additives.

The other additives can be present in varying amounts. Usually, for oils to be used in an engine, the total amount of these additives will range from about 0.1 to 15 weight percent and more usually from about 0.5 to 10 weight percent. The individual additives may vary in amount from about 0.01 to 10 percent weight of the total composition.

These additives include ashless dispersants such as succinimides, hydrocarbyl alkylene polyamines, etc., corrosion inhibitors such as metal dithiophosphates, etc., detergents such as the sulfonates, phosphonates, phenates, etc., viscosity index improvers such as the polyisobutylenes, polyacrylates, etc., pour point depressants such as the polymethacrylates, polyacrylamides, etc., extreme pressure additives, and other additives designed to accomplish specific objectives.

LUBRICATING OILS The oils which find use in this invention are oils of lubricating viscosity derived from petroleum or synthetic sources. The oils can be paraffinic, esters, naphthenic, halo-substituted hydrocarbons, asphaltic or combinations thereof. Oils of lubricating viscosity normally have viscosities in the range of 35 to 50,000 Saybolt Universal Seconds (SUS) at 100 F. and more usually from about 50 to 10,000 SUS at 100 F.

The following examples are included to further illustrate but not limit the invention.

EXAMPLE I OXIDATOR B TEST The stability of an oil composition against oxidative change is measured by the time required for the consumption of one (1) liter of oxygen by 100 grams of the test oil at 340 F. (171 C.). For covenience the actual test uses 25 grams of oil and the results are corrected to a IOO-gram sample. A catalyst containing a mixture of soluble salts is added to the oil which provides parts per million (p.p.m.) copper, 80 p.p.m. iron, 4.8 p.p.m. manganese, 1100 p.p.m. lead and 49 p.p.m. tin. The test can be continued for a total of 10 hours and the number of liters of oxygen taken up in this period is reported. In addition, the viscosity of the oil is measured at the start of the test and at the end of the l0-hour period. The increase is reported as a percentage of the original value. Table I reports the values obtained from subjecting a variety of oil compositions to the Oxidator B test. The amount of each additive used is expressed as percent weight of the total composition. The oil used in these tests is a solvent refined neutral hydrocarbon oil having a viscosity of 480 Saybolt Universals Seconds at F. (38 C.).

TABLE I.OXIDATOR B TEST Additive oi the Other additives,

invention percent weight Lifetime Comhrs. for 1 Oz uptake, Vis pound liter liters/ increase, No. Percent, wt. A B C D E uptake hours percent muwvoucl en mall.

1 Other additives:

A=2,2-bls(l-hydroxy-i-polypropylenephenyl)disulflde 75 percent weight in oil. B=air-bis(l-hydroxy-c-methyl-4-polypropyienepheny0disuifide, 76 percent weight in o C=A polyisobutenylsucclnimide produced by reacting a succinic anhydrlde of a polybutene (PIBSA 950) having a number average molecular weight of about 950 with tetraethylenepentamine (TEPA) at a mole ratio of TEPA to PIBSA of 0.87, approximately 44 percent weight active additive in oil solution.

D =Terephthalie acid.

E=99.3 percent weight of a pol sobutenylsuccinimide similar to that of Compound 0 except that succinic anhy ride oi a polybutene (PIBSA 640) having a number average molecular weight oi. about 640 is used to reduce the mole ratio oi TEPA to total PIB SA to 0.50, and 0.7 Eercent weight of terephthalic acid.

F=Bis(3,5-di-t-butyl-4-hydroxyp enyDmethylene-au antioxidant currently in commercial use and used as a reference in the above tests.

! Reaction product obtained from Example VII below.

' See Table A above.

From the above results it can be Seen the O l C P permit loadings in excess of 3000 pounds. The results of {ions of the invention exhibit at least as much and gcntesting oil compositions of this invention as described erally greater resistance to oxidativc change than the bov are t f th i T bl 11A, reference oil composition.

TA L EXAMPLE IIFALEX EXTREME PRESSURE TEST B E FALEX EXTREME PRESSURE TEST The capability of a lubricating oil composition to lubri- Oil No. Shearload, lbs. Oil No. Shear load, lbs. cate under extreme pressures can be measured by this 1 575 1 600 test. The Falex machine is manufactured by the Faville- 11300 [Le Vally Corporation of Chicago, 111. In this test, two .2% 8 opposing stationary V-blocks are pressed by a nutcracker 113001 1: arrangement of lever arms toward each other against an 5%,223" interposed rotating steel shaft. The rotating shaft is 4,150

driven by a chuck through a brass shear pin. The V-block and pin test specimens are immersed in a vessel of test lubricant at a preselected temperature. The machine is Q2%? 6 $}:f g figg ifgg lggggggfifs figgfggg i fi g 3 352 3 operated at 290 r.p.m. and the specimens are broken in usedln these tests. Seizure did not occur under maximum loading.

at 300 pounds loading. During the test, loading between the. V-blocks and the pin is increased automatically until seizure occurs. This failure point is indicated by shearing 0f the brass pin holding the rotating shaft. The load at In the above Falex test all compositions of the invention exhibited extreme pressure lubricating properties equal to and in many cases markedly superior to the failure in pounds is taken as a quantitaive measure of the refefePce 011 Fomposition Composition 20 extreme pressure properties of the oil composition. Min- @Xhlblted Pamculafly Outstanding extreme PTBSSIIFe P P' l il may f il t 600 t 900 nd oil i h d erties and the results of further testing of the reaction ateextreme pressure additives will fail at 1000-2000 p uct from Example VII with other additive combinapoundszand very effective extreme pressure additives will tions is shown in Table IIB.

TABLE IIB.FALEX EXTREME PRESSURE TEST Oil No.

Additive 1 i 1 In the same 4.80 8138 neutral oil as above examples.

1 See Example 1 for composition of Additives C and D.

' Additives are expressed as percent weight of the total oil composition. Additive F=Same as E except does not contain terephthalic acid.

5 Additive G=Tetrapropenylsuccinic acid.

Reaction product from Example VIL The results shown in Table IIB above demonstrate that the reaction product of Example VII both alone and in combination with other additives enhances the extreme pressure lubrication properties of the oil. It may be noted that Oil No. 28 containing only Additive G, an acidic species, performed no better than the base oil which, as stated above, usually results in seizure at about 600 to 900 pounds loading. It may also be noted that Oil No. 30 containing only the reaction product from Example VII resulted in extreme pressure lubrication to loadings approximately 50 percent larger than the base oil either with or without Additive G. However, Oil Nos. 25, 27 and 29, which contain both the reaction product of Example VII and an acid species (Additives D or G), gave extreme pressure lubrication to greatly increased loadings and in one case (Oil No. 25) to the limits of the machines.

EXAMPLE III-BEARING CORROSION TEST In addition to conferring beneficial properties to lubrieating oils, additives must not cause certain harmful effects. One harmful effect to be avoided is corrosion of engine parts, particularly the nonferrous parts which come in contact with the oil. Corrosion of this nature caused by a particular additive is measured by immersing separate strips of lead and copper in the oil composition to be tested and maintaining the 'oil at a temperature of 295 F. (146 C.) for 20 hours. Both strips are weighed to determine weight loss. In addition, the copper strip is washed with potassium cyanide solution to remove copper compound deposits and re-weighed. The results of testing several additive combinations of the invention are shown below in Table HI. The base oil used is the same 480 SUS neutral oil used in the above examples.

1 See previous examples for compositions.

Reported as milligrams lost.

1 Reported as B/A B=Cu loss before KCN wash and A=Cu loss after KCN wash.

Same composition as 9 and 20 respectively except without Additive D.

Although the above data, particularly the results from Oil Nos. 9, 9-A, 20 and 20-A, do not conclusively demonstrate the necessity for the presence of a mild organic acid species to retard nonferrous corrosion, the results do appear to demonstrate there is no adverse effects from having the acid species present. This is desirable since the presence of these acid species enhance the extreme pressure lubrication properties of the oil as shown in Table IIB above.

The following Examples IV, V, and VI demonstrate the preparation of three compounds useful as antioxidants in extreme pressure additives in the compositions of this invention. The preparation of the three compounds is the same up to a point as set forth below under the heading of General Preparation of Additive Intermediate.

General preparation of additive intermediate To a 500-ml. 3-neck flask equipped with stirrer, thermometer, nitrogen bleed, dropping funnel and condensor is added 2,6-di-t-butylphenol (20.6, 0.1 mole) in dimethyl sulfoxide (50 ml.). A solution of potassium hydroxide (13.2 g., 0.2. mole) in water (15 ml.) is prepared, cooled and diluted with dimethyl sulfoxide. This solution is added to the phenolic solution above with stirring under a nitrogen blanket. The solution is cooled to 10 C. 5 with an ice water bath and carbon disulfide (7.6 g., 0.1 mole) is added to the stirred'solution while maintaining the temperature at 10 C. Stirring is continued at 10 C. for 30 minutes after addition is complete. Cooling is discontinued and the temperature of the stirred solution is allowed to rise to room temperature. At this point, the synthesis is continued with the nonisolated intermediate as shown in Examples IV, V, and VI below.

EXAMPLE IV Preparation of Compound III-3,5-di-t-butyl-4- hydroxybenzoic acid, dithiol-n-octyl ester To the nonisolated intermediate prepared according to the general preparation above is added concentrated hydrochloric acid (10 ml.) slowly with stirring followed by the addition of l-bromo octane (19.3 g., 0.1 mole). Stirring is continued for one hour at room temperature. The temperature is raised to 70 C.i10 for one hour. The reaction mixture is then cooled and poured into ice water (500 ml.) with stirring to yield a liquid product. The aqueous mixture is extracted three times with a 200 ml. of ether. The combined organic phases are dried over anhydrous sodium sulfate and the solvent is removed under vacuum on a rotary evaporator to yield 35.4 grams of product suitable for use without further purification. Recrystallization of a portion of the product from mixed hexanes yields a red crystalline solid. Elemental analysis sulfurfound=16.3% w.; calculated 16.2% w.

EXAMPLE V Preparation of Compound XII1,4-dihydro-l-ox0- 2,6-di-t-butyl-4-dimethylthiomethylenebenzene To the nonisolated intermediate obtained from the general preparation above is added iodomethane (28.4 g., 0.2

mole) slowly with stirring. Stirring is continued at room temperature for one hour followed by heading to 70 0.:10" for one hour. The reaction mixture is cooled to room temperature and 200 ml. of water is added followed by stirring for an additional 15 minutes. The aqueous mixture is extracted with ether (250 ml.) three times. The combined organic phases are dried over anhydrous sodium sulfate and the solvent is removed on a rotary evaporator to yield 24.4 grams of product suitable for use without futher purification.

EXAMPLE VI Preparation of Compound IXbis(3,5-di-t-butyl-4- hydroxybenzoic acid, dithio)methylene ester To the nonisolated intermediate obtained from the general preparation above is added diiodomethane (13.4 g., 0.05 mole) and stirring is continued at room temperature for one hour followed 'by heating to 70 C.- -l0 for one hour. The reaction mixture is cooled and poured into ice water (500 ml.) with stirring. The aqueous mixture is extracted three times with ether (200 ml.). The combined organic phases are dried over anhydrous sodium sulfate, filtered and the solvents are removed on a rotary evaporator. The solid product obtained is dissolved in a mixed hexanes solvent to produce a saturated solution. The solution is chilled in a refrigerator overnight. The mother liquor is decantered from the crystals obtained and the crystals are taken up in 750 m1. of mixed hexanes. The volume of the second solultion is reduced to about half and cooled to obtain crystallization. The crystals thus obtained are suitable for use as a lubricating oil additive.

EXAMPLE VII Preparation of Compound Xbis(3,5-di-t-butyl-4- hydroxybenzoic acid, dithio)ethylene ester To a l-liter flask equipped with a stirrer, thermometer, nitrogen-bleed, dropping funnel and condensor is added 2,6-di-t-butylphenol (61.8 g., 0.3 mole) in dimethyl sulfoxide (75 ml.) and hexane (75 ml.). A solution of potas- 13 sium hydroxide (39.6 g., 0.6 mole) in water (45 ml.) is prepared, cooled and diluted with dimethyl sulfoxide (25 ml.). This solution is added to the phenolic solution above with stirring under a nitrogen blanket. The solution temperature is maintained at 30 :5. The solution turned green. "While maintaining this temperature, carbon disulfide (23 g., 0.3 mole) is added with stirring. Stirring is continued at room temperature for one hour during which time the reaction mixture turned deep red. 'While maintaining the temperature at 30 C., as above, concentrated hydrochloricacid (30 ml.) is added, followed by addition of ethylene dichloride (14.8 g., 0.15 mole). The reaction mixture is heated to 70 C.'il0 C. for one hour followed by cooling to40 C. Distilled water (300 ml.) is

added and the reaction'mixture is stirred for five minutes. The reaction mixture is placed in a separatory funnel and the organic phase is removed. Distilled water (500 ml.) is added to the remaining aqueous phase, which is then extracted three times with Chevron Thinner 250* (600 ml.). The combined organic phases are washed three times with water (700 ml.) and are dried over anhydrous sodium sulphate. The organic phase is filtered and the volatiles are removed under vacuum on a rotary evaporator to yield 73.4 g. of product suitable for use without further purification.

Subsequent analysis of the reaction product obtained above demonstrates that it contains significant portions of Compound X, the bis-ethylene ester, and Compound XVII, the dithiacyclopentylidenebenzene, the structures of which were confirmed by nuclear magnetic resonance spectroscopy.

Compound XVII, the dithiacyclopentylidenebenzene was recovered and was tested in the Oxidator B and Falex Extreme Pressure tests described above. The results obtained were not as good as those obtained from the use of the crude reaction mixture as the lubricating oil additive.

What isclaimed is:

1. A lubricating oil composition comprising:

(a) a major amount of an oil of lubricating viscosity;

and

(b) an amount effective to impart antioxidation and extreme pressure lubrication properties to said oil of a compound having one of the following formulae:

*Chevron Thinner 250 is a high-aniline water-white petroleum naphtha available from Standard Oil Company of California.

wherein:

(1) R and R each represent an alkyl group which sterically hinders the adjacent hydroxy, thiol or 0x0 group;

(2) R R and R each represent alkyl, hydroxyalkyl, hydroxyalkyloxyalkyl, hydroxyalkylpoly- (oxyalkyl), aralkyl or aryl;

(3) R represents an alkylene group;

(4) each R represents hydrogen, alkyl or aryl;

(5) X represents oxygen or sulfur; and

(6) Y represents hydrogen or a metallic cation selected from alkali metal and alkaline earth metal cations.

A lubricating oil composition of claim 1 wherein:

(1) R and R each represent a branched alkyl containing from 4 to 10 carbon atoms;

(2) R R and R each represent alkyl containing from 1 to 20 carbon atoms, a hydroxyalkyl containing from 2 to 5 carbon atoms, a hydroxyalkyloxyalkyl containing from 4 to 10 carbon atoms, a hydroxyalkylpoly(oxyalkyl) containing 2 to 5 carbon atoms in each alkyl moiety and from 2 to 5 oxyalkyl units, aralkyl containing 7 to 8 carbon atoms or aryl containing 6 to 7 carbon atoms;

(3) R represents an alkylene group containing from 1 to 8 carbon atoms;

(4) each R7 represents hydrogen; and said oil contains from 0.1 to 5 percent weight of said compound.

A lubricating oil composition comprising:

(a) a major amount of an oil of lubricating viscosity;

and

(b) an amount of eifective to impart antioxidation and extreme pressure lubrication properties to said oil of a lubricating oil additive which is the fourth reaction product formed by:

(1) combining in an inert solvent and under an inert atmosphere (a) about one equivalent of a phenol having nuclear alkyl substituents in both positions ortho to the hydroxy group which sterically hinder said hydroxy group with (b) about two equivalents of a proton acceptor selected from alkali metal hydroxides, alkoxides and amides to obtain a first reaction product;

(2) combining said first reaction product with about one equivalent of carbon disulfide to ob tain a second reaction product;

wherein Steps (1) and (2) are conducted at a temperature of from 0 C. to 50 C.,

(3) combining at from room temperature up to 30 C. said second reaction product with about one equivalent of a proton donor selected from hydrochloric acid, sulfuric acid and nitric acid to obtain a third reaction product; and

(4) combining at from room temperature up to C. said third reaction product with about one-half equivalent of a dihaloalkane containing at least two carbon atoms in which the halogen substituents are on adjacent carbon atoms to obtain said fourth reaction product.

4. A lubricating oil composition of claim 3 wherein said dihaloalkane is a dichloroalkane containing from 2 '16 References Cited UNITED STATES PATENTS to 30 carbon atoms and said oil contains from 0.1 to 5 per- 2,073,841 3/1937 Humphreys et aL cent of said fourth reaction product.

5. A lubricating oil composition of claim 3 wherein 5 FOREIGN PATENTS 665,107 1/1962 Great Britain 25242.7

said dihaloalkane is a dichloroalkane containing from 2 to 8 carbon atoms and said oil contains from 0.1 to 5 percent of said fourth reaction product.

6. A lubricating oil composition of claim 3 wherein said diahaloalkane is 1,2-dich1oroethane and said oil contains from 0.5 to 3 percent of said fourth reaction product.

DANIEL E. WYMAN, Primary Examiner 10 A. H. METZ, Assistant Examiner US. Cl. X.R.

25246.7, 48.2, 400 R, 406; 260-327 M, 455 R