GB604388A - Improvements in or relating to extreme pressure lubricating oil compositions - Google Patents

Abstract

An extreme pressure lubricating composition comprises a lubricating oil to which is added a compound of the general formula <FORM:0604388/III/1> where x is an integer and R an alkyl group. Such compounds are the chlorbenzyl esters of alkyl xanthic acids. The lubricating oil may be a light petroleum hydrocarbon, benzene or any of its homologues, an alcohol, ether or ester, fatty vegetable or mineral oil or a mineral hydrocarbon or the like, the additive being dissolved, dispersed or emulsified according to the oil used. The additive is present in the minor amount, usually 1-10 per cent, and preferably not less than 7 per cent, though more concentrated compositions, say 50 per cent, may be prepared and diluted immediately before use to about 7 per cent. Any chlorbenzyl xanthate may be used, such as trichlor-, dichlor- or o-chlorbenzyl sec-butyl xanthate, tetrachlor-, trichlor- or o-chlorbenzyl isopropyl xanthate, or the trichlorbenzyl esters of octadecyl, heptadecyl, tetradecyl, dodecyl, decyl, octyl, heptyl, hexyl, amyl, ethyl and methyl xanthic acids. In an example, trichlorbenzyl ethyl xanthate (for preparation see Group IV (b)) is added to high viscosity mineral lubricating oil and tested by standard methods for determining the extreme pressure characteristics. Specification 604,370 is referred to.ALSO:Chlorbenzyl esters of alkyl xanthates of formula <FORM:0604388/IV(b)/1> are prepared by reacting a chlorbenzyl chloride with an alkali metal xanthate and separating the alkali metal chloride formed. In an example, 460 parts of trichlorbenzyl chloride (2.0 molecular proportions) are added in a slow stream to sodium ethyl xanthate prepared by reacting 190 parts (2.5 molecular proportions) of carbon disulphide, 91.5 parts of 96.5 per cent caustic soda (2.2 molecular proportions) and 808 parts of ethyl alcohol. (All parts are by weight.) The temperature is maintained at 50-55 DEG C. during the addition of the chloride, and then the mixture is refluxed for about an hour. Excess alcohol is removed under vacuum and the residue washed with water and dried. The trichlorbenzyl chloride used is prepared by nuclear chlorination of dry toluene (1500 parts) at 20 DEG C. in the presence of iron filings (15 parts) increasing the temperature to 70 DEG C. during the last part of the run, and the purified product chlorinated in the presence of ultra-violet light at 160 DEG C. until the gain in weight was that calculated for trichlorbenzyl chloride. Specification 604,370 is referred to.