US2409687A

US2409687A - Sulfur and metal containing compound

Info

Publication number: US2409687A
Application number: US547640A
Authority: US
Inventors: Dilworth T Rogers; John G Mcnab
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1943-05-10
Filing date: 1944-08-01
Publication date: 1946-10-22
Anticipated expiration: 1963-10-22

Description

- exam. no,

October 22, 1966 UNITED STATES PATENT @FFICE SULFUR AND METAL CONTAINING COM'POUND Delaware No Drawing. Application August 1, 1944, Serial No. 547,640

2 Claims.

This invention relates to a novel type of organic compound containing sulfur and a metal.

This is a continuation-impart of our co-pending application Serial No. 486,428, filed May 10, 1943.

It is known that the addition of certain types of metal organic compounds to lubricating oils improves various properties thereof, such as their oiliness characteristics and their detergent action in engines, particularly manifested in the maintenance of a clean engine condition during operation. Various metal compounds which have been used for such purposes include the metal derivatives of such organic compounds as fatty acids, naphthenic acids, sulfonic acids, alcohols, phenols and ketones. However, these various metal compounds generally have the disadvantage of tending to corrode alloy bearings, such as those of cadmium-silver and copper-lead, now so widely used in automotive engines, and this is especially true in engines which operate at relatively high speeds and high temperatures. It is an object of the present invention to provide a new class of addition agents for oils which are to be used as crankcase lubricants for internal combustion engines and which exhibit the desirable properties of promoting general engine cleanliness, improving oil film strength, reducing ring sticking, piston skirt varnish formation and the like, and which not only do not exhibit the corrosion promoting tendencies characteristic of the above metal compounds, but also inhibit the corrosiveness of oils to which they are added.

The new class of products which have now been found to be highly satisfactory as addition agents are the products obtained by the reaction of elemental sulfur with metal salts of hydroxy and mercapto substituted aromatic sulfides. When these compounds are to be used as additives for mineral oils, they should contain as a substituent in the aromatic nucleus at least one alkyl group, the total number of carbon atoms in such groups being at least five. It has been found that such products are usually satisfactory in inhibiting bearing corrosion and in being adaptable to use with a wide variety of petroleum lubricating oil base stocks. The reaction for the preparation of the additives may generally be brought about in a solution of lubricating oil or other petroleum oil, whereby concentrates may be prepared which may be conveniently stored or shipped and added to lubricating oils when required.

The new sulfur containing compositions herein described are also useful as antioxidants for other purposes when incorporated in organic materials products in lubricating oil compositions.

other than lubricating oils, as will be more fully explained hereinafter, and in some cases it may not be necessary to have alkyl groups present in order to impart sufiicient solubility. The invention also includes the reaction products of sulfur with compounds analogous to the salts of phenol sulfides and thiophenol sulfides, but containing selenium and tellurium in place of oxygen or sulfur, and with compounds in which aromatic nuclei other than benzene nuclei are present.

In the aforementioned co-pending application Serial Number 486,428 we have described the preparation of reaction products of elemental sulfur with metal phenates and the use of such It was there shown that the sulfur atoms were probably linked directly to the metal atoms in the molecules of the reaction product. It is believed that the same type of reaction occurs when metal salts of phenol sulfides and the like are treated with sulfur, giving compounds in which the sulfur atoms are thought to be attached directly to the metal atom.

Some of the more preferred products to be used in accordance with the present invention are those obtained by reaction of sulfur with the following compounds:

Barium tert.-octyl phenol sulfide Barium di-tert.-amyl phenol sulfide Calcium isohexadecyl phenol sulfide Tin wax-alkylated salicylic acid sulfide Magnesium tert.-amyl phenol sulfide The invention includes the reaction products of sulfur with not only the normal metal salts of phenol sulfides, thiophenol sulfides and the like, but the basic metal salts as well. In a normal phenol sulfide salt of a divalent metal the ratio of metal to phenol sulfide is 1:1 as in the folowing formula:

In a basic salt the ratio of metal to phenol sulfide may be 2:1 or even 3:1. In the case of a 2:1 ratio the formula may, for example, be

MOH MOE 3 In the case of a 1.5: 1 ratio the formula may be MOH MOH MO o In the case of a 3:1 ratio the formula may be MOH M011 Intermediate ratios of metal to phenol sulfide, such as 1.8:1 or 2.311, may occur in' which mixtures of the above types of basic compounds are obtained. These basic salts are formed, for example, by reacting phenol sulfides with more than the amount of metallic oxide or hydroxide necessary to form the normal salts. Reaction products of sulfur with basic metal salts of alkyl phenol sulfides are particularly useful in extreme pressure lubricants. These products are also especially advantageous for imparting color stability to lubricants.

The new class of addition agents employed in accordance with the present invention may be defined in its broadest scope as the reaction products of elemental sulfur with a metal salt of a compound having the formula in which Ar is an aromatic nucleus and may, for illustration, be a benzene nucleus, or it may consist of a plurality of rings, as in biphenyl, or it may be a condensed nucleus, exemplified by naphthalene, anthracene and the like. R in the formula is hydrogen or at least one organic group and is preferably an alkyl group. X in the formula is a non-metal of group VI of the periodic table; Y is a member of the sulfur family; a: is an integer from 1 to 4; and R, is an organic group which may be either aryl, alkyl, aralkyl, or alkylaryl, and which may contain substituent atoms or groups, such as halogen, nitro, amino, hydroxy, alkoxy, aroxy, mercapto, carboxy, and the like. The metals which may be substituted for the hydrogen in the -XH group of the above formula in forming salts of such compounds may be any metals, the most important for the purposes of the present invention being calcium, barium, strontium, magnesium, and zinc, although for some purposes corresponding compounds containing tin, lead, aluminum, cobalt or nickel will also be found to be especially desirable.

Compounds particularly suited for the purposes of the present invention are formed by reacting sulfur with a compound of the formula where R represents at least one alkyl radical attached to the nucleus, the total number of carbon atoms in all of such radicals being at least five when the compound is to be dissolved in hydrocarbon oils, X is oxygen or sulfur, M is a divalent metal of group 11 of the periodic table, and a: is an integer from 1 to 4.

It should be understood that the above general formulas include compounds in which various substituent atoms or groups may be attached to the aromatic nucleus, such as alkyl, cycloalkyl, aralkyl, aryl, carboxyl, hydroxyl, alkoxy, aroxy, sulfhydryl, nitro, ester (organic and/0r inorganic), keto, amino, aldehydo, chlormethyl. aminomethyl, alkyl thiomethyl, alkyl xanthomethyl, metal substituted carboxyl, metal substituted sulfonic acid, metal substituted hydroxyl or sulfhydryl groups, halogen atoms, etc. Different types of atoms or groups may be attached to the same aromatic nucleus. Alkyl radicals attached to the nucleus may have a total of five to twelve carbon atoms in all of such groups, but in some cases as many as sixteen to twenty or more carbon atoms in a single group, or a plurality of groups, may be preferred. If more than one alkyl group is present in a single molecule, whether or not attached to the same aryl nucleus, such groups may be alike or different. Such allzyl or other hydrocarbon groups may contain substituent groups, such as those named above as substituents in the aromatic nucleus. The positions of the various groups or atoms attached to the aromatic nucleus may be any positions relative to one another.

Alkyl phenol sulfides, whose metal salts may be used to prepare the reaction products of the present invention, may be illustrated by the following general classes of compounds:

1. Alkyl phenol thioethers:

OH OH 2. Alkyl phenol disulfides:

OH OH and on on 3. Polymers of alkyl phenol sulfides:

OH OH OH dearth doom tives for lubricating oils, exceptionally good results can be obtained by employing metal salts of alkyl phenol sulfides having C1s-C2o branched chain alkyl groups. These can be conveniently radicals particularly preferred in the compounds, it being understood that the list is merely illustrative and does not restrict the scope of the groups of the formulas. These include n-butyl,

prepared from phenols which have been alkylated 5 isobutyl, tert.-butyl, n-amyl, isoamyl, cyclohexyl, with what are essentially branched chain polyn-octyl, isooctyl, tert.-octyl, dodecyl, octadecyl, mers of n-butene obtained as by-product's in the wax chain and C16-C24 branched chain radicals. manufacture of secondary butyl alcohol from pe- Structures of several typical compounds whose troleum refinery C4 hydrocarbon fractions. salts may be reacted with sulfur in accordance It should be understood that generally, with the present invention may be given to show throughout this specification, the term alkyl what is believed to be the relative positions or the phenol sulfide is meant to include not only the various groups in the aromatic nuclei, but it is monosulfides but also the diand polysulfides to be understood again that these formulas are and polymers of alkyl phenol sulfides as well. given as illustrations only. These typical exam- Thus, although reaction of an alkylated phenol ples are the following: with sulfur dichloride (S012) will give essentially (8) OH OH an alkyl phenol monosulfide, small amounts of polysulfides and of polymeric materials will also be formed. This is even more usually the result when more than the theoretically required proportion of sulfur halide is used in preparing the CBHH CaHn alkyl phenol sulfide, as, for example, when 2 (b) OH OH moles of alkyl phenol sulfide are treated with 1.5 moles of sulfur dichloride. Similarly, the alkyl phenols may be treated with more than theoreti- 5 cal quantities of sulfur monochloride (SzClz) or with mixtures of sulfur monoand dichloride or can CaHu with first one halide and then the other. (0) OH OH Other compounds Whose metal salts may be used in accordance with this invention are illus- 3 CZHOC (300ml trated by the following:

HO-(R) CsHa-SeCsHs (R) -OH CsHn s n H (d) OH OH HO(R)CH S C'H(R) OH CsHiOOCUS; 00003111 s H s HO--(R)CsH:SCsH(R)OH 5H" 05H NH Specific examples of compounds which may be HO (R)CH: S CQH7(R) OH treated with sulfur in accordancewith the present invention include the following, which are CH not to be construed as limiting the invention in HO-(R) C1oH5S-C10H5(R) -OH ny m HO ..(OR) C H s C H (OR) OI-1 Calcium tert.-octyl phenol sulfide Barium 2,4-di-tert.-amyl phenol sulfide HO"'(OR)CGH3SCBHZ(R (OR) OH Cobalt tert.-amyl phenol sulfide I-IO-(R) (NH2)C6H2S-C6H2(NH2) (ID-OH Barium salt of 2-hydroxy-3,5-di-tert.-amyl-4- 60 diethylamino diphenyl sulfide fig-(R) (OH) C6H2"'sC6H2(oH) (PU-OH Zinc salt of salicylic acid sulfide octyl ester HS-(R) CsH3-SC6H3(R)SH Barium 2-stearoyl-4-amyl phenol sulfide Mixed calcium-barium tert.-octyl phenol sulfide HO (R) (COR)C6H2S C6H2(R) (COR) OH Tin salt of C1e-C20 branched chain alkyl phenol HO- (R) CeH3-S-C5H4-OROH sulfide Barium salt of bis(2,4-diamyl phenol) -4-amylphenol dithioether (prepared from 2 moles of HO' (R)C6H3-S C6H4OR 2,4-di-tert.-amyl phenol and one mole of p- HO-(R)C6H3SC6H4-COOR tert.-amyl phenol, sulfurized with sulfur chlo- HO (NH2) ride and neutralized with barium hydroxide) HO (R) When the salts employed are those of polyvalent metals, it is not essential that all of the valences HO-(R) C6H3 S C6H3(R)N(R1) (R2) be satisfied by hydroxyaryl sulfide groups; some o c 1-1 s c 1-1 05 of them may be satisfied by other acidic organic (straight or branched chain) grgup: sugh as carboxy,daroxy. alkoxy, orgaltlnosu s i ute inorganic aoi groups such as p os- HO(R)C6H3 S R' phoric, phosphorous, thiophosphoric, thiophos- HO(R)CsH3-SC5H3(R)NH2 phorous, sulfonic, sulfinic, phosphonic, phosphinic, and the like. In these formulas R represent organ: Thus, for example, the present invention also i'adlcals'prefera'bly alkyl w includes reaction products of sulfur with such In all of the above described type formulas, compounds both general and specific, where R is used to represent an organic radical, such radicals may be Calcium mixed salt of tert.-amyl phenol sulfide illustrated by the following species, which are 7 and iso-octyl salicylate Aluminum mixed salt of tert.-octyl phenol sulfide and stearic acid Tin mixed salt of di-tert.-amyl phenol sulfide and naphthenic acids Barium mixed salt of tert.-octyl phenol sulfide and petroleum mahogany sulfonic acids Nickel mixed salt of tert.-amyl phenol sulfide and amyl xanthic acid Zinc mixed salt of isododecyl phenol sulfide and methyl cyclohexyl thiophosphoric acid Nickel mixed salt of tert.-amyl phenol sulfide and oleic acid Magnesium mixed salt of tert.-octy1 phenol sulfide and cetyl phenol As has been mentioned previously in this specification, the term phenol sulfide is meant to include not only the moncsulfide but also disulfides, polysulfides, or polymers or mixtures of any of these in any proportion.

For the objects stated. the metal salts of allzylated phenol sulfides have been preferably prepared from phenolic compounds readil obtained by synthetic alkylation of the simple phenols, followed by treatment with a sulfur chloride. then neutralization with a metallic base.

Suitable synthetic alkyl phenols for preparing the desired phenol sulfide salts are preferably those containing secondary or tertiary alkyl radicals because alkylation of a simple phenol occurs more readily with branched aliphatic reactants. Commonly. the alkylation reaction involves. a condensation of olefins with the simple phenols, the reaction being catalyzed by anhydrous metal halides, boron fluoride, hydrofluoric acid, stannic chloride with hydrogen chloride, sulfuric acid. phosphoric acid or certain activated clays. As olefinic reactants, refinery gases containing propylene, 'butylenes, amylenes, etc.. are economically useful, although individual olefins or olefin-containing mixtures derived from other sources may be used. Preferred individual olefins are the butenes, amylcnes. and olefin polymers, such as cliisobutylene or triiso-butylene, or normal olefin polymers or copolymers of normal and secondary or tertiary olefins, or copolymers of olefins and diolefins. The reaction temperature is usually controlled to avoid side reactions. In employing sulfuric acid, a liquid phase reaction at relatively low temperature is preferred, while with phosphoric acid the reaction may be carried out in the vapor phase.

Suitable alkylated phenols for conversion to phenol sulfides may be thus prepared by alkylating phenol, cresol, naphthol or other phenolic compounds. High molecular weight alkylated phenols may also be used, for example, those prepared by condensing phenols with chlorinated petrolatum or chlorinated parafiin wax or with a chlorinated kerosene or gas oil. Naturally occurring phenols, such as those obtained by a1- kaline extraction of certain petroleum stocks or those obtained from cashew nut shell liquid or those obtained from other vegetable oil sources may likewise be used. Halogenated or nitrated phenols will also find application in this invention, particularly if the final additive is to be employed in extreme pressure lubricants.

One class of alkyl phenols whichare particularly preferred are those which have been prepared by alkylation of phenol with an olefin polymer such as diisobutylene or a refinery butene polymer oil. Alkylation of phenol with about an equal molar proportion of diisobutylene gives ptert.-ctyl phenol, also known as diisobutyl phenol or tetramethyl butyl phenol. This phenolic material is especially desirable because of the ease of its preparation and because products made from it are highly satisfactory for the present invention. In many instances, however, a higher degree of alkylation may be advantageous, and for this reason the phenol may be alkylated with as much as two molecular equivalents of diisobutylene to give, under proper conditions, essentially ditert.-octyl phenol; or it may be alkylated with other olefin polymers such as triisobutylene, or other isobutylene polymers. For many purposes it is preferable to employ alkylated phenols having branched chain alkyl groups of from 16 to 30 carbon atoms. Suitable products may be prepared by alkylating phenol with certain of the polymeric materials obtained as by-products in the manufacture of butyl alcohol from petroleum refinery butenes. These consist essentially of polymers of n-butone with small percentages of isobutene and other olefins and give a-lkylated phenols having branched chain alkyl groups of l6-20 or 20-24 carbon atoms, depending on the polymeric material used in the alkylation. It should be understood that in many cases the alkylation products may be mixtures of various compounds rather than entirely one specific alkyl phenol. and that it is intended to use such mixtures in practicing this invention.

For conversion of phenols to phenol sulfides the phenol is reacted with sulfur dichloride to produce essentially a phenol mcnosulfide having a thioether linkage, while sulfur monochloridc may be used to produce essentially the phenol disulfide. About one-half to one mol of sulfur halide is used with each mol of phenol. and the reaction is preferably carried out in a solvent such as dichlorethane, choloform, petroleum naphtha, benzol, Xylol, toluol. and the like.

For converting the phenol sulfides to metal salts, it is usually sufficient merely to add a metal or a metallic oxide, hydroxide, sulfide, alkoxide, hydride, or carbide to a mineral oil solution or other solution of the phenol sulfide at an elevated temperature. Thus. barium salts of alkylated phenol sulfides are prepared by reacting the sulfide with barium hydroxide, preferably in the form of the hydrate, Ba(Ol-I)z.8H2O. The calcium salts may be prepared by reacting alkyl phenol sulfides with calcium methylate or other calcium alcoholate. In some instances it may be preferable to prepare heavy metal salts from the alkali metal salt by double decomposition. In many cases the metal alkyl phenol sulfide prepared by neutralization with a metal hydroxide may occur as a hydrated salt. Use of hydrated salts prepared in this manner or by any other method is also contemplated in the processes of the present invention.

In accordance with the present invention, the metallic salt of a phenol sulfide or other metallic derivative of a hydroxy or mercapto aromatic sulfide is caused to react with sulfur. This may be accomplished by adding the sulfur in elemental form to a heated solution of the metallic compound. The sulfur may be used in any of its a-llotrcpic forms.

In carrying out the reaction described above the proportions of sulfur and metal salt of phenol sulfide are so chosen that from 0.1 to 2.5 atomic proportions of sulfur are react-ed with one atomic proportion of metal, the preferred ratio being within the limits of about 0.5 to 1.5 atomic proportions of sulfur for each atomic prosearch Room portion of metal. This preferred ratio gives the products the optimum content of sulfur to impart to them the maximum amount of inhibiting power.

If desired, the products used in accordance with this invention may be prepared by the simultaneous reaction of a phenol sulfide, a metal oxide or hydroxide and elemental sulfur. However, in order to avoid the formation of oil-insoluble materials, it is preferred to first form the metal salt of the phenol sulfide and then react this with sulfur.

Although the reaction can be brought about by fusing the metal salt with sulfur, it is more convenient to carry out the reaction with the aid of solvents, particularly high boiling hydrocarbon solvents, such as xylol or a petroleum fraction. A particularly preferred reaction medium is a lubricating oil fraction, since the final reaction product can thus be obtained as a mineral oil concentrate of the desired additive, which may be conveniently shipped or stored as such and then readily blended with the lubricating oil base stock in the desired concentration to form a finished lubricating oil blend.

The additives may generally be prepared by first dissolving an alkylated phenol sulfide in a mineral oil or other suitable solvent and treating the same with a metal hydroxide, e. g.,

Ba (OH) 2.8H2O

at about 80-200 C., preferably 110-150 C. After a further period of heating free sulfur is added, heating being continued at 100-230 C., preferably at l50-200 C., to complete the reaction. The period of heating will generally be from about minutes to 1 hour, although in some cases a longer period may be required. When the material will no longer stain a strip of copper immersed in it for about 10 seconds at l80-190 C., the reaction is considered complete. The product is then filtered, giving a concentrate of the desired additive. If the products are found to have a slight odor of hydrogen sulfide, this can be substantially eliminated by treating with a small proportion (2-5%) of barium hydroxide or calcium oxide or hydroxide at 150 C., followed by filtering and blowing with nitrogen at 100- 120 C. In some cases improved products may be obtained by heat treatment of the metal phenol sulfide before or after reaction with sulfur. The heat treatment may be conducted, for example, at 150 C. for 10l5 hours.

It has been found that good results are obtained when preparing these additives in mineral oil if a minor proportion of a higher alcohol, such as stearyl, lauryl or cetyl alcohol, or wool fat alcohol or the like, is added to the reaction mixture in which the compounds of the present invention are prepared. This alcohol reduces foaming during the process and acts as an auxiliary solvent for the final product. The best results are obtained by adding a suflicient quantity of alcohol to give a concentration of about 3% to about in the final additive concentrate. It has been determined by test that substantially none of the higher alcohol enters into the reaction.

It has also been found that products of better oil solubility can often be obtained when carrying out the reaction with sulfur in the presence of a small proportion of an olefinic material, such as a tetraisobutylene, cracked wax or an unsaturated alcohol.

Generally, the additives of the present invention are most advantageously blended with lubrieating oil base stocks in concentrations between the approximate limits of 0.02% and 5.0% and preferably from 0.1% to 2.0%, although larger amounts may be used for some purposes. The exact amount of addition agent required for maximum improvement depends to a certain extent on the particular products used, the nature of the lubricating oil base stock and the general operating conditions of the engine in which the lubricant is to be employed. This same general range of concentration will also be effective when the additives are to be used in greases and in extreme pressure lubricants, although in the latter instance greater amounts, up to 20%, may also be employed.

It has been pointed out elsewhere in this specification, it is often convenient to prepare concentrates of the additives in oil, containing, say, to 75% of effective addition agent, the concentrate later being added to a suitable lubricating oil base stock to give a finished blend containing the desired percentage of additive. Thus, when using a concentrate, 2.5% of this material may be blended with a suitable base stock to give a finished oil containing 1% of effective addition agent.

In the following examples are described various preparations of products in accordance with this invention and the results obtained on testing the same in various lubricating oil blends. It is to be understood that these examples, given for illustrative purposes only, are not to be construed as limiting the scope of the invention in any way.

Example 1 Tertiary octyl phenol was prepared by alkylating phenol with diisobutylene, using stannic chloride and HCl catalysts substantially as described in the Buc U. S. Patent 2,332,555.

A 30% solution of tert.-octyl phenol was prepared by dissolving parts by weight of the alkylated phenol in 233 parts of chloroform. Then over a period of three hours 37.5 parts of sulfur dichloride was added, the temperature being maintained at 20--25 C. Agitation was continued for an additional hour at the same temperature, after which the solution was heated under refiux for two hours. The solvent was stripped off at a maximum temperature of 100 C. and the alkyl phenol sulfide blown with carbon dioxide until free of H01. The resulting tert.-octyl phenol sulfide was a dark brown resinous product completely soluble in mineral oils.

382 parts by weight of solvent-free tert.-octyl phenol sulfide prepared as above was dissolved in 618 parts of refined mineral lubricating oil (52 seconds Saybolt viscosity at 210 F.) at a temperature of 70-80 C. To the agitated oil solution 125 parts of commercial stearyl alcohol was added and the temperature was then raised to 110 G. Then 278 parts of barium hydroxide octahydrate, Ba(OH)z.8I-I2O, was gradually added in small portions, the rate of addition being governed by the amount of foaming of the reaction mixture. During this step the mixture was blown with nitrogen to facilitate removal of water vapor. Following the addition of the barium hydroxide, agitation and blowing were continued at C. for 30 minutes, then Hyflo filter aid was added (2 lbs. per 100 gallons of mixture), the temperature raised to C. and the mixture filtered through a filter press, the concentrate being recycled until a, perfectly clear product was obtained. The final product was a mineral oil concentrate containing 40% barium tert.-octyl 11 phenol sulfide, 10% stearyl alcohol, and 50% mineral lubricating oil. It contained 3.2% sulfur and 9.3% barium.

Example 2 As starting material for the preparation of a reaction product of a barium salt, there was used a concentrate containing 40% by weight of barium tert.-octyl phenol sulfide, 10% of stearyl alcohol and 50% of a refined mineral oil of 52 seconds viscosity Saybolt at 210 F., prepared as described in Example 1. 500 g. of this concentrate was treated with 10 g. of sulfur by heating the concentrate to 120 C. and adding the sulfur gradually with agitation over a period of 10 minutes, during which the temperature rose to 190 C. The temperature was then held at 160l80 C. for a total reaction period of 2%; hours and the final product filtered. The resulting material contained 4.87% sulfur.

Example 3 The purpose of the following test was to determine the corrosion inhibiting effect of adding a small quantity of the product prepared as in the preceding example to a lubricating oil base, this being a well refined solvent extracted parafflnic type mineral lubricating oil of S. A. E. 20 grade. The oil contained 0.625% of additive concentrate prepared in accordance with Example 2, which is equivalent to about 0.25% of the actual additive. A comparative test was made with a sample of the unblended oil base.

The tests were conducted as follows: 500 cc. of oil to be tested was placed in a glass oxidation tube (13 long and 2 diameter) fitted at the bottom with a ,41" bore air inlet tube perforated to facilitate air distribution. The oxidation tube was then immersed in a heated bath so that the oil temperature was maintained at 325 F. during the test. Two quarter sections of automotive bearings of copper-lead alloy of known weight having a total area of 25 sq. cm. were attached to opposite sides of a stainless steel rod which was then immersed in the oil and rotated at 600 R. P. M., thus providing sufficient agitation of the sample during the test. Air was then blown through the oil at the rate of 2 cu. ft. per hour. To increase the severity of the test, the hearings were washed and weighed at the end of each four hour period and then polished and reweighed before continuing for another four hour period. The results, given in Table I, show the cumulative weight loss at the end of each four hour Although in most instances the additives of the present invention will of themselves impart sufficient improvement to lubricating oils to give very satisfactory results, still greater improvement may often be obtained by employing these addition agents in conjunction with other additives of the detergent type, such as metal soaps, metal phenates, metal alcoholates, metal phenol sulfides, metal organo phosphates, thiophos- 12 phates, phosphites and thiophosphites, metal sulfonates, metal thiocarbamates, metal xanthates and thioxanthates, and the like.

Thus the addition agents of our invention may be used in mineral lubricating oils in conjunction with one or more of the following representative materials:

Barium tert.-octyl phenol sulfide Barium di-tert.-amyl phenol'sulfide Cobalt tert.-amyl phenol sulfide Tin salt of wax alkylated phenol sulfide Calcium mahogany sulfonates Barium mahogany sulfonates Strontium mahogany sulfonates Magnesium mahogany sulfonates Calcium isohexadecyl phenol sulfonate Calcium double salt of octadecyl phenol sulfonic acid Barium phenate-zinc sulfonate of isohexadecyl phenol sulfonic acid Calcium salt of amyl phenol-formaldehyde condensation product Magnesium cetyl phenate Calcium ortho stearoyl phenate Nickel oleate Calcium dichlorostearate Calcium phenyl stearate Barium octadecylate Aluminum-calcium mixed soap of fatty acids from oxidation of petroleum fractions Nickel dibutyl dithiocarbamate Nickel amyl xanthate Barium dioctyl dithiophosphate Zinc methyl cyclohexyl dithiophosphate Calcium dihexadecyl monothiophosphite Zinc tert.-octy1 phenol sulfide thiophosphate Calcium cetyl phosphate Magnesium lauryl salicylate Zinc diisopropyl salicylate Calcium phenate-barium carboxylate of octadecyl salicylic acid Tin naphthenate Aluminum naphthenate Particularly advantageous are lubricant compositions in which the additives of the present in vention are employed in conjunction with metal salts of petroleum mahogany sulfonic acids. Examples of such compositions include the following:

Per cent 1. Additive concentrate containing 40% of sulfur-barium tert.-octyl phenol sulfide reaction product 1.0

Calcium mahogany sulfonates 1.5

Mineral lubricating oil 97.9 2. Additive concentrate containing 35% of sulfur-calcium tert.-amyl phenol sulfide reaction product 2.5 Barium mahogany sulfonates 1.5 Mineral lubricating oil 96 3. Zinc mahogany sulfonates 2.3

Additive concentrate containing 40% of sulfur-barium-2A-diamyl phenol sulfide reaction product 2.0 Mineral lubricating oil 94 The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paraffinic, naphthenic, asphaltic or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may be refined by Dt'irllbil unnuconventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents of the type of phenol, sulfur dioxide, furfural, dichloro ethyl ether, nitrobenzene, crotonaldehyde, etc. Hydrogenated oils or white oils may be employed as well as synthetic oils prepared, for example, by the polymerization of oleflns or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. In certain instances cracking coil tar fractions and coal tar or shale oil distillates may also be used. Also, for special applications, animal, vegetable or fish oils or their hydrogenated or voltolized products may be employed, either alone or in admixture with mineral oils.

For the best results the base stock chosen should normally be that oil which without the new additives present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils or other oils, no strict rule can be laid down for the choice of the base stock. Certain essentials must of course be observed. The oil must possess the viscosity and volatility characteristics known to be required for the service contemplated. The oil must be a satisfactory solvent for the additive, although in some cases auxiliary solvent agents may be used. The lubricating oils, however they may have been produced, may vary considerably in viscosity and other properties depending upon the particular use for which they are desired, but they usually range from about 40 to 150 seconds Saybolt viscosity at 210 F. For the lubrication of certain low and medium speed Diesel engines the general practice has often been to use a lubricating oil base stock prepared from naphthenic or aromatic crudes and having a Saybolt viscosity at 210 F. of 45 to 90 seconds and a viscosity index of 0 to 50. vHowever, in certain types of Diesel service, particularly with high speed Diesel engines, and in aviation engine and other gasoline engine service, oils of higher viscosity index are often preferred, for example,*up to '75 to 100, or even higher, viscosity index.

In addition to the materials to be added according to the present invention, other agents may also be used, such as dyes, pour depressors, heat thickened fatty oils, sulfurized fatty oils, organo metallic compounds, metallic or other soaps. sludge dispersers, antioxidants, thickeners; viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, voltolized fats or fatty oils, voltolized mineral oils, and/0r voltolized waxes and colloidal solids such as graphite or zinc oxide, etc. Specific examples of such other agents include phenyl alpha-naphthylamine, voltolized sperm oil, 2,6-di-tert.-butyl-4-methyl phenol, sulfurized sperm oil, p-tert.-amyl phenol sulfide, dibenzyl disulfide, polyisobutylene, sulfurized wax olefins, tricresyl phosphate, diamyl trisulfide, and the condensation product of phenol with a sulfur chloride-diisobutylene reaction product. Solvents and assisting agents, such as esters, ketones, alcohols, amines, nitriles, aldehydes, halogenated or nitrated compounds, and the like, may also be employed.

Assisting agents which are particularly desirable are the higher alcohols having eight or more carbon atoms and preferably 12 to 20 carbon atoms. The alcohols may be saturated straight and branched chain aliphatic alcohols such as octyl alcohol (Cal-1110K), lauryl alcohol (C12H25OI-I), cetyl alcohol (CrsHazOI-I), stearyl alcohol, sometimes referred to as octadecyl alcohOl (CrcHsrOI-I), heptadecyl alcohol (C17H35OH), and the like; the corresponding olefinic alcohols, such as oleyl alcohol; cyclic alcohols, such as naphthenic alcohols; and aryl substituted alkyl alcohols, for instance, phenyl octyl alcohol, or octadecyl benzyl alcohol or mixtures of these various alcohols, which may be pure or substantially pure synthetic alcohols. One may also use mixed naturally occurring alcohols such as those found in wool fat (which is known to contain a substantial percentage of alcohols having about 16 to 18 carbon atoms) and in sperm oil (which contains a high percentage of cetyl alcohol); and although it is preferable to isolate the alcohols from those materials, for some purposes, the wool fat, sperm oil or other natural products rich in alcohols may be used per se. Products prepared synthetically by chemical processes may also be used such as alcohols prepared by the oxidation of petroleum hydrocarbons, e. g., paraffin wax, petrolatum, etc.

These assisting agents serve to enhance the detergent and sludge dispersive qualities and aid the solubility of the metal-containing additives and at the same time impart some oiliness properties to the lubricating oil compositions.

In addition to being employed in crankcase lubricants, the additives of the present invention may also be used in extreme pressure lubricants, engine flushing oils, industrial oils, heat transfer media, general machinery oils, steam cylinder oils, cutting oils, insulating oils, process oils, rust preventive compositions, hydraulic oils and greases. Also their use in motor fuels, Diesel fuels and kerosene is contemplated. A particular application in this regard is their use in motor fuels containing tetraethyl lead or other anti-knock agents, the additives of the present invention serving not only as antioxidants for the fuel but also as stabilizers for the anti-knock agent itself. Sinse these additives exhibit antioxidant properties and are believed also to possess ability to modify surface activity, they may be employed in asphalts, road oils, waxes, fatty oils of animal or vegetable origin, soaps and plastics. Similarly, they may be used in natural and synthetic rubber compounding both as vulcanization assistants and as antioxidants, and generally they may be used in any organic materials subject to deterioration by atmospheric oxygen.

The present invention is not to be considered as limited by any of the examples described herein which are given by way of illustration only, but it is to be limited solely by the terms of the appended claims.

We claim:

1. As a new composition of matter an oil-soluble sulfur containing product obtained by reacting elemental sulfur with a compound of the formula where R is an alkyl radical of at least 5 carbon atoms, X is a member of the group consisting of oxygen and sulfur, M is a divalent metal of group II of the periodic table and selected from the group consisting of calcium, barium, strontium,

magnesium, and zinc, and as is an integer jrom 1 to 4.

2. The method of preparing an oil-soluble sulfur containing product having antioxidant properties in the presence of organic materials which comprises reacting elemental sulfur with a compound of the formula 16 where R is an alkyl radical of at least 5 carbon atoms, X is a member of the group consisting of oxygen and sulfur, M is a divalent metal of group II of the periodic table and selected from the group consisting of calcium, barium, strontium, magnesium, and zinc, and a: is an integer from 1 to 4.

DILWORTH T. ROGERS. JOHN G. McNAB.