US2306354A - Lubricating oil - Google Patents

Description

atented Dec. 22, 194-2] LUBRICATIIIN G OIL Elmer W. Cook, New York, N. Y., and William D.

Thomas, Jr.,

Stamford, Conn., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine N Drawing. Application November 29, 1941,

Serial N o.

Claims.

This invention relates to lubricating oils, part cularly those of the type known as crankcase 0115. Although the lubricating oils of the present inventiorare highly desirable for use in the crankcases of passenger automobiles, they are especially valuable for heavy duty use in trucks, buses, aero ilane and marine Diesel engines which operate for ong periods of time at high temperatures.

When conventional lubricating oils are subjected to high operating temperatures for long periods of time, as in heavy duty service, they tend to decompose with the formation of objectionable complex oxidation and decomposition products. These acidic oxidation products corrode certain alloy bearings such as copper-lead, silver-cadmium, nickel-cadmium, etc., which are commonly employed in internal combustion engines. These decomposition products also tend to polymerize under the high temperature conditions obtaining i: the engine to form sludge which precipitates when the engine is cooled or when fres.- oil is added. The precipitated sludge clogs the oil filter and becomes caked on heated metal surfaces to form lacquer-like deposits which may cause the piston rings or even the cylinder itself to stick.

Certain anti-corrosion agents, 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. These anti-corrosion agents have no detergent properties, however, and while they 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 of the oil, they do not act to disperse the sludge or prevent the formation of the varnish deposits mentioned above.

Attempts have been made to overcome these deficiencies by the addition of a. detergent to the oil. However, the detergent tends to remove the corrosion inhibitor from the material surface, thus rendering it inactive for its intended purpose. The compounds which we add to lubricating oils in accordance with the present invention possess not only excellent corrosion inhibiting properties but also have some detergent characteristics and thus enable us to provide a lubrieating oil having a single additive efiective to inhlbit corrosion, sludge and varnish formation, ring sticking and other dimculties experienced with lubricating oils serving in a' heavy duty capacity. These objectives and others which will appear hereinafter are accomplished by us by providing a hydrocarbon lubricating oil containing small amounts of alkyl and cycloalkyl substituted aryloxyalkylol sulfides.

Another advantage to be obtained by the use of our alkyl and cycloalkyl aryloxyalkylol sulfides is their solubilizing action on certain materials which are known to be good detergents, antioxidants, etc. or have good corrosion inhibiting properties but which cannot normally be used on account of their oil insolubility. Certain dithiophosphates, such as di-(p-tert. amyl phenyl) dithiophosphate; calcium, barium, aluminum, zinc and magnesium stearates, palmitates, naphthenates, etc. are difficultly soluble in lubricating oils but because of their solubility in the compounds described herein it is possible to add them to oils in this way in amounts sufficiently large for them to be effective.

The alkyl and cycloalkyl substituted aryloxyalkylol sulfides employed by us in preparing our improved lubricating oils may be represented by the general formula:

OH (])H r r O 0 I I R1 S n R:

I I R1 R3 in which X1 and X2 are alkylene radicals containing 2 to 4 carbon atoms inclusive, n is a positive integer not more than 2, and R1 and R2 are members of the group consisting of alkyl, cycloalkyl, and hydrogen radicals, at least one R1 and at least one R2 being a member of the group consisting of alkyl and cycloalkyl radicals.

The alkyl and cycloalkyl substituted aryloxyalkylol sulfides of our invention are prepared by reacting an alkyl or cycloalkyl substituted aryloxyalkylol compound with sulfur chloride or sulfur dichloride depending upon the type of sulfide desired as the reaction product. The alkyl and cycloalkyl substituted aryloxyalkylol compounds which weemploy in our reaction have the general formula OX-OH in which X is an alkylene group of 2 to 4 carbon atoms such as --CHz-CHz--,

-c11cm (IJHJ --CH2CH2CH2, etc. and either or both groups designated as R1 may be alkyl radicals of from 1 Vii following example in which particular parts by weight, solvents, etc. are indicated merely for purposes of illustration and our invention is not to be limited to th particular compound described since as stated above the invention in its broader aspects is not limited thereto.

7 EXAMPLE 56 parts by weight of 2,4-diamyl phenoxy ethanol was dissolved in 50 parts of carbon disulfide. 10.5 parts by Weight of sulfur dichloride dissolved in 10 parts of carbon disulfide was then added with stirring. 3 parts by weight of anhydrous aluminum chloride was then added and the mixture stirred and warmed gently under a reflux condenser on a steam bath for minutes. At the end of this time the evolution of hydrogen chloride had practically stopped and the reaction mixture was then cooled and stirred with cold dilute hydrochloric acid. 60 parts by weight of toluene was then added and the organic layer separated and washed three times with water.

Ordinarily we carry out the reaction with the reactants dissolved in a suitable solvent such as carbon disulfide, ethylene chloride, petroleum naphtha, nitrobenzene, etc. The reaction mixture with the catalyst present is then heated until the evolution of HCl has substantially stopped. The mixture is then treated with cool dilute HCl, or other acid such as sulfuric, acetic, etc., and the product recovered by extraction with toluene or other suitable solvent. The product can be purified by washing with water, in which it is insoluble, and the solvents removed by evaporation.

It will be understood of course that the preparation of the disulfides with sulfur chloride proceeds in the same way under the same reacting conditions. It will also be understood that the cycloalkyl substituted aryloxyalkylols may be employed in place of the 2,4-di-tert. butyl phenoxy ethanol illustrated in the above equation in the same manner and using the same molecular proportions.

Metal salts of these compounds may also be prepared by reacting the compounds just described with appropriate molecular amounts of finely powdered metallic aluminum, metallic magnesium turnings, calcium metal, etc. A small amount of mercury chloride may be added to start the reaction. The reaction mixture may be gently heated on a steam bath at first but may require cooling later because of the exothermic character of the reaction. Metal salts may also be prepared by heating the compounds described with an alcoholate of a lower boiling alcohol, sodium methylate for example, under conditions such that the lower alcohol is driven off. The aluminum salt of 2,4-diamyl phenoxy ethanol monosulfide, for example, may be prepared by this method.

The preparation of 2,4-diamyl phenoxy ethanol monosulfide will now be described in detail in the The solvent was then evaporated leaving diamyl phenoxy ethanol monosulfide as orange-red oil, easily soluble in gasoline (in; lubricating oils but only slightly soluble in water.

The compounds described above are heat stable and not easily decomposed in the oil because of the high operating temperature often encountered. They are also practically water insoluble and are not extracted from the oil by contact with water or tend to promote the formation of emulsions with Water in the oil.

The alkyl and cycloalkyl substituted aryloxyalkylol sulfides 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 compound. In lubricating oils intended for ordinary purposes where high temperatures occur only occasionally from 0.1 to 0.8% of the aryloxyalkylol sulfide is sufiicient. In an oil intended for heavy duty service it is generally advisable to use a little more, as for example, 0.5 to 3.0% in the oil.

The extremely high solubility of these compounds in hydrocarbon oils leads to another im- 'portant 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 the ordinary type of lubricating oils to the extent of 50-80% for storage and shipping purposes. For this reason it will be understood that the claims are intended to include lubricating oils of such high concentration unless otherwise limited.

The effectiveness of the alkyl and cycloalkyl substituted aryloxyalkylol sulfides in lubricating oils as corrosion inhibitors, detergents and antioxidants is demonstrated by the following results obtained by subjecting an S. A. E. No. 10 solvent refined Pennsylvania oil to the standard Underwood oxidation test. A representative alkyl substituted aryioxyalkylol sulfide, 2',4-diamy1 phenoxy ethanol monosulfide, was dissolved in a sample of the oil in amounts corresponding to 0.4% by weight and compared with the same oil without benefit of the additive.

The test consisted in heating 1500 cc. of the oil to 325 C. and continuously sprayi g a portion of the hot oil against a by 10" freshly sanded copper strip and two freshly sanded bearthen examined for specific gravity, neutralization number, naphtha insolubles, and the bearings were examined for weight TABLE I Underwood oxidation test [011: Solvent refined Pennsylvania S. A. E. No. l

A. P. I. gravity 30.4"]

solvent refined Pennsylvania S. A. E. No. oil was tested by the catalytic Indiana test.

ing corrosion rates were determined by weighing the strips after 70 hours immersion. The results of this test were as follows:

TABLE II Indiana catalytic oxidation test-70 hours at 41 F.

' CuPb bear- Additive Cone. mg loss mg 3 Per cent None 215 2,4diamyl phenoxy ethanol monosulfide- O. 4 23 The results of both the Underwood and Indiana tests show the marked corrosive inhibitive effects What we claim is: 1. A lubricating oil composition containing a compound having the general formula sisting of alkyl and cycloalkyl radicals.

2. A lubricating oil composition containing a compound having the general formula O i. A

in which X1 and X2 are alkylene radicals containing 2 3. A lubricating oil composition containing a compound having the general formula OH OH MUS R2 R1 R2 in which n is a positive integer not more than 2, and R1 and R2 are alkyl radicals.

4. A lubricating oil composition containing di- (2,4-diamyl phenoxy ethanol) monosulfide.

,5. A lubricating oil composition containing di- (2,4-di-tert. amyl phenoXy ethanol) monosulfide.

ELMER W. COOK. WILLIAM D. THOMAS, JR.