US2319662A - Lubricating oils - Google Patents

Description

atented ay i, 1943 F i CE Thomas, Jinn, Stamford, Conn, American Cyanamid Company,

assignors to New York,

N. iL, a corporation of Maine No Drawing. Application Qctober 31, 1941, Serial No. 417,311

'2' Claims. '(iUl. 252-426) This invention relates to lubricating oils, particularly those of the type known as crankcase oils. Although the lubricating oils of the present invention are highly desirable for use in crankcases of passenger automobiles they are especially valuable for heavy duty use in truck, bus, aeroplane, marine and Diesel engines which operate for long periods of time at high temperatures.

The principal objects of the invention are to provide a lubricating oil of the heavy duty type which possesses excellent detergent properties, is resistant to oxidation and sludge formation, is non-corrosive to alloy bearings and other metal parts under conditions of extreme service and which is free from film formation and ring sticking tendencies.

These objects, and others which will appear hereinafter, are accomplished by us by providing a hydrocarbon lubricating oil containing a class of compounds having detergent, and other desirable properties. These compounds are designated broadly as acyl phenol monosulfides having the general formula Reem mrm la Y Y When conventional lubricating oils are sub-- jected to high operating temperatures for long periods of time, as in heavy duty service, they tend to decompose with the formation of complex and objectionable oxidation and decomposition products. Under the high temperature conditions obtaining in the engine these decomposition products polymerize to form lacquer-like deposits on or between the moving parts causing these parts to stick. Even larger quantities of polymerization products remain dispersed in the partly oxidized crankcase oil. and are rapidly precipitated and form a sludge when the engine cools or when fresh oil is added to the engine. These prec pitated sludges become caked on heated metal surfaces and cut down the effective life of the engine.

A number of oil soluble detergents of the type of metal soaps, phenolates and alcoholates have been proposed and used in crankcase oils to dissolve or disperse the sludge and prevent lacquer deposits and stuck piston rings. Unfortunately, however, the great majority of these substances increase the rate of oxidation in a manner somewhat analogous to the accelerating action of the various metallic soaps or driers on the oxidation of varnish films, and their presence results in an increased concentration of acidic oxidation products in the oil. Increased quantities of these acidic oxidation products in the oil create in turn an even more serious difficulty for they attack and corrode alloy bearings commonly employed in internal combustion engines. Alloys composed of copper-lead, silver-cadmium, nickelcadmium, etc. are widely used and are subject to attack by the acidic oxidation products formed in the oil.

Certain anti-corrosion agents which have no detergent properties, such as triphenyl phosphite and sulfurized sperm oil, have been added to lubricating oils in order to counteract the corrosive effect of the oxidation products of the oil. Although the detergents which have been previously mentioned and the anti-corrosion agents perform their individual functions in lubricating oils the two separate chemicals do not cooperate to produce a satisfactory anticorrosion and detergent action when used together. The function of a. corrosion inhibitor is to cover the bearing surfaces and other corrodable parts of the engine with a passivating film that prevents corrosion of the metal by the organic acids and other corrosive productsin the oil. A detergent, as its name implies, operates to remove adhering solids in the metal parts of the engine and thus produce a clean metal surface. Consequently mixtures of a detergent with a corrosion inhibitor have proven to be in effective over any extensive period of time since the detergent action of the sludge inhibitor tends to remove the corrosion inhibitor from the metal surface thus rendering it ineffective for the purpose intended.

The acyl phenol monosulfides and metal salts thereof which we employ avoid the above described difiiculties by possessing detergent, antisludging and corrosion inhibiting action in the single compound. The compounds are heatstable and are not easily decomposed in the oil because of the high operating temperatures often encountered. They are also practically 'waterinsoluble and are not extracted from the oil by contact with water. In addition to their detergent and dispersing properties they have oiliness properties and many of them also-act to lower the pour point of the oil.

The acyl phenol monosulfides and their metal salts which we employ are so very efiective that it is possible to improve lubricating oils to a-great extent by the, use of very small amounts of the compounds. In lubricating oils intended for ordinary service where high temperatures occur only occasionally, from 0.1-0.8% of the acyl phenol monosulfide or its salt issufilcient. In heavy duty service it is generally advisable to use a little more, as for example 0.5-3.0% in the oil.

The extremelyhigh solubility of these compounds in hydrocarbon oils leads to another important advantage, namely, the ease with which these compounds are blended with lubricating oils. This step is further simplified by our practice of dissolving them in ordinary types of lubricating oils to the extent of 50-80% for storage and shipping purposes. For this reason it will be understood that, the appended claims are intended to cover lubricating oil compositions of such high concentration unless otherwise limited.

The acyl phenolate monosulfides which we employ to prepare the improved lubricating oils of our invention are made by reacting an alkyl substituted phenol monosulfide with an acyl halide in the presence of anhydrous aluminum chloride. Ordinarily we employ 2 moles of the acylating agent for each mole of the phenol monosulfide in order that each phenyl radical of the phenol monosulfide may be substituted with at least one acyl group. Th reaction may be carried out in either one or two steps, i. e. the phenol monosulfide may be first reacted with the acyl halide followed by the addition of aluminum chloride and further reaction, or all of these reactants may be mixed together and the mixture heated. In either caseheating is continued until the evolution of hydrogen chloride which is eliminated in the reaction has subsided. The product of this reaction is probably a complex aluminum salt of the acyl phenol monosulfide. This product is then decomposed by the addition of an excess of cold dilute hydrochloric acid.

The acyl phenol monosulfide thus formed may be separated from the reaction mixture by extraction with a solvent followed by washing and evaporation of the solvent. Various metal salts of the acyl phenol monosulfide may be obtained by neutralization with an appropriate salt-forming base or by double decomposition with its sodium salt. The compounds thus prepared are straw-colored to dark reddish-brown liquids of varying viscosity and are found to be extremely soluble in gasoline and lubricating oils.

The alkyl substituted phenol monosulfides which we employ in the above reaction are wellknown products having the general structural formula:

in which R1 and R2 are alkyl groups of 1-20 carbon atoms and in which the OH group may occupy a. position either ortho or para to the sulfur linkage. The alkyl groups R1 and R2 tend to promot solubility of the compounds in lubricating oils and in general the longer the chain the more soluble the compounds will be in oil.

' The acyl halides which we employ may be of different kinds such as for example butyroyl chloride, caproyl chloride, lauroyl chloride myristoyl chloride, stearoyl chloride, benzoyl chloride, amyl benzoyl chloride, amyl oxyacetyl chloride, naphthenoyl chloride, phenyl acetyl chloride, phenoxy acetyl chloride, phenyl stearoyl chloride and many others. The naphthenoyl chloride mentioned above is composed of a mixture of various cycloaliphatic acyl halides such as are prepared from naphthenic acids, a product of the petroleum industry.

The metal radicals which we introduce into the acyl phenol monosulfide molecule to form salts thereof include those metal salt-forming radicals such as aluminum, lead, zinc, magneslum, calcium, barium, strontium, etc. The metal salts may be prepared by simply neutralizing the acyl phenol monosulfide with an appropriate metal oxide or hydroxide or by methods of double decomposition, as illustrated in the specific example. We prefer to employ the alkaline earth metal salts of these compounds in our improved lubricating oil compositions.

The preparation of a number of these acyl phenol monosulfides and salts thereof will now be described in detail in the following examples. It should be understood, however, that this description is given merely for purposes of illustration and our invention is not to be limited to the particular compounds or the particular method of preparation described since other acyl phenol monosnlfldes may be employed without departing from the scope of the invention as set forth in the appended claims.

EXAMPLE 1 2-stearoz/l-4-amyl phenol monosulfide 92 parts by weight of 4-amyl phenol monosulfide was dissolved in parts of A. S.,T. M. and 153 parts of stearoyl chloride added with stirring. The mixture was then heated under a reflux condenser With stirring for 30 minutes after which time the evolution of hydrogen chloride had subsided. After cooling, 23 parts of anhydrous aluminum chloride was added and the resulting mixture heated to refluxing temperatures with stirring. Refluxing and stirring were continued for 2 hours, at the end of which time very little hydrogen chloride was being evolved. The reaction mixture was then cooled and 200 parts of cold dilute hydrochloric acid added. The mixture was stirred thoroughly and parts by weight of toluene added. The aqueous layer was then separated and the solvent layer Washed once with warm, dilute hydrochloric acid and twice with hot water. The solvent was then evaporated and 2-stearoyl-4-amyl phenol monosulfide recovered as a reddish-brown liquid, readily soluble in gasoline and lubricating oil, but practically insoluble in water.

EXAMPLE 2 9.5 parts by weight of barium the barium hydrate had reacted and the water of neutralization had been expelled. Toluene was added from time to time to replace the solvent evaporated. After cooling, the solution was filtered from traces of inorganic barium salts and the solvent removed by evaporation. The barium salt thus obtained was an extremely viscous reddish-brown liquid believed to have the following formula:

Because of the high viscosity of this product, it is preferable to add a quantity of light lubricating oil before the solvent is completely evaporated. By doing this a 50% solution of the barium salt of 2-stearoyl-4-amyl phenol monosulfide in lubricating oil is obtained which is much more convenient for handling and blending.

EXAMPLE "3 The heavy metal salts of Z-stearoyl-d-amyl phenol monosulfide, such as those of tin and zinc, may be conveniently prepared by double decomposition in an ethanol-toluene solution, between the sodium salt of 2-stearoyl-4-amyl phenol monosulfide and the appropriate metallic inorganic salt.

For example, 30 parts of 2-stearoyl-4-amyl phenol monosulfide was dissolved in a mixture of 30 parts of ethanol and parts of toluene. 2'? parts of a sodium ethylate solution, prepared by dissolving 23 parts of metallic sodium in 377 parts of ethanol, was heated and the mixture warmed up to 75 C. until homogeneous. The temperature.v was then dropped to about 50 C. and 6.4 parts of stannous chloride, dissolved in parts of ethanol, was gradually added with stirring.

The mixture was then heated to 75 C. and

parts of toluene added. After cooling, the solution was filtered from sodium chloride and the filtrate evaporated. The st'annous salt of 2- stearoyl-l-amyl phenol monosulfide remained as a viscous, reddish-brown product.

EXAMPLE 4 The aluminum. salt of 2-stearoyl-4-amyl phenol monosulfide was prepared by dissolving 20 parts of the product prepared in Example 1 in 40 parts of toluene followed by the addition of 5 parts of aluminum butylate. The mixture was stirred and heated at 110 C. for 30 minutes. The solvent was then evaporated, the last traces under reduced pressure, and the aluminum salt of 2- stearoyl-4-amyl phenol monosulfide recovered as a'viscous, reddish-brown liquid.

This compound was prepared by condensing 2 moles of lauroyl chloride with 1 mole of 4-amyl phenol monosulfide in the presence of 0.70 mole of anhydrous aluminum chloride following the procedure described in detail in Example 1. The product was a yellow colored liquid insoluble in water but easily soluble in gasoline and lubricating oils.

The various metallic salts of this compound were prepared in the same manner described in Examples 2 to 4.

EXAMPLE 6 2-butyryl-4-amyl phenol monosulfide OH OH CaH1CO This product was prepared by condensing 2 moles of butyryl chloride with 1 mole of 4-amyl phenol monosulfide in the presence of 0.70 mole of anhydrous aluminum chloride. The product was a straw colored liquid insoluble in water but easily soluble in gasoline and lubricating oil. The various metal salts are prepared as previously described.

EXAMPLE 7 2 -stearoyl4-methyl phenol monosulfide en 0 ll CnUarr-UO- -S' CEO-(11111.15

l 0 Ha C H:

This compound was prepared by condensing 2 moles of stearoyl chloride with 1 mole of ii-methyl phenol monosulfide in the presence of 0.70 mole of anhydrous aluminum chloride by the procedure described in detail in Example 1. The product was a yellow liquid insoluble in water and readily soluble in gasoline and lubricating oil.

EXAMPLE 8 EXAMPLE 9 d-stearoyl-Z-amyl phenol monosulfide O 0 H H (7 unis-'0 ([7-(3 nHas CsHn 051111 This compound was prepared by condensing 2 moles of stearoyl chloride and 1 mole of p-(2 amyl phenol) monosulfide in the presence of 0.70 mole of anhydrous aluminum chloride. The product was a reddish-brown liquid insoluble in water but easily soluble in gasoline and lubricating oil.

EXAMPLE 100 parts by weight of 6-stearoyl-2-amyl phenol monosulfide was dissolved in 70 parts of ethanol and 120 parts of toluene and neutralized with barium hydrate. The solution was then filtered and the solvent evaporated, leaving the barium salt of 6-stearoyl-2-amyl phenol monosulfide as a thick reddish-brown liquid.

EXAMPLE l1 Z-naphthenoyZ-el-amyl phenol monosulfide dissolved in an alcohol-toluene solution.

EXAMPLE 12 Z-naphthenoyl-ai-methyl phenol monosulfide This compound was prepared by condensing 104 parts of naphthenoyl chloride with 50 parts of p-cresol monsulfide dissolved in 50 parts of naphtha solution in the presence of parts of anhydrous aluminum chloride. The product was a brown liquid practically insoluble in water but readily soluble in gasoline and lubricating oil.

The barium salt of this compound was prepared by heating 35 parts of 2-naphthenoyl-4-methyl phenol monosulfide, dissolved in parts of ethanol and 50 parts of toluene, with 5 parts of barium hydrate. The product was a viscous, stiif, brown colored liquid which Was blended with 50% of a light lubricating oil for ease of handling.

The effectiveness of the above-described compounds in preventing corrosion of bearings in lubricating oils, under conditions of severe service, is demonstrated by the following results obtained by subjecting a S. A. E. No. 10 solvent refined Mid-Continent oil to the Standard Catalytic Indiana test. Samples of the oil containing varying amounts (OB-0.4%) of the acyl phenol monosulfide were compared with the oil contain-' ing no additive.

TABLE I Catalytic Indiana test Mid-Continent solvent refined oil 70 hours at 341 F. Copperdead bearing TABLE II Catalytic Indiana test Solvent refined Pennsylvania oil Bearing \ddithu loss, mg.

Cu-Ph (.ontrol 201 Barium 2-stcaroyl-4-amyl phenol monosulfide. 0.3 10 2-stearogl-4-amyl phenol monosulfide 0.3 2 2-napht enoyl-i-nmyl phenol monosulfide"... 0 4 RI! 4 ill) 2-butyryl4-amyl phenol monosulfide 0:

1 Yl i i."

in which R1 and R2 are alkyl groups having 1 to 20 carbon atoms and R3 and R4 are members of the group consisting of alkyl, aryl, alkoxyalkyl, aroxyalkyl, aralkyl, alkaryl and cycloalkyl radicals and metal salts thereof.

2. A lubricating oil composition containing a predominating amount of a lubricating oil 'and (Ll-3% of a compound selected from the group consisting of acyl phenol monosulfides of the general formula general formula $1) Oil H0 0 aamss o tt Y in which R1 and R2 are alkyl groups having 1 to 20 carbon atoms and R3 and Br are members of the group consisting of alkyl, aryl, alkoxyalkyl, aroxyalkyl, aralkyl, alkaryl and cycloalkyl radicals and alkaline earth metal salts thereof.

4. A lubricating oil composition containing a predominating amount of a lubricating oil and a minoramount of a compound selected from-the group consisting of acyl phenol monosulfides of minor amount of 2-stearoyl-4-amyl phenol monothe general formula, sulfide.

o OH HO O 6. A lubricating oil composition containing a II II predominating amount of a lubricating oil and 5 a minor amount of the barium salt of 2-stearoyl- I 4-amyl phenol monosulfide.

'I. A lubricating oil composition containing a predominating amount of a lubricating oil and a minor amount, of the barium salt of 2-lauroylin which R1 and R2 are alkyl groups having 1 to 10 4-amy1 phenol monosulfide. 20 carbon atoms and metal salts thereof.

5. A lubricating oil composition containing a I ELMER W. COOK. predominating amount of a lubricating oil and a WILLIAM D. THOMAS, JR.