GB604370A - Improvements in or relating to extreme pressure lubricating oil compositions - Google Patents

Abstract

The film strength or E.P. properties of lubricating oils is improved by the addition of a minor proportion (usually 1-10 per cent) of a chloraralkyl ester of a thio acid of the type <FORM:0604370/III/1> , where R is a chlor substituted aralkyl radicle, Y is oxygen or sulphur, at least one of them being sulphur, and R1 represents an alkyl, aryl, aralkyl or alkylaryl radicle or may be identical with R. The chlor benzyl xanthates, which form the subject of Specification 604,388 are excluded. Examples are a chlor phenalkyl ester of a thio acid, such as a chlorophen-alkyl trithiocarbonate; a chlorbenzyl ester of a thio acid, e.g. a chlorbenzyl thiocarbonate, or a chlorbenzyl ester of a thiocarbonic acid, such as trithiocarbonic acid. Among the compounds described are di-(trichloro benzyl) trithiocarbonate, and trichlor benzyl butyl trithiocarbonate. Chlorbenzyl esters or mono- and dithiocarbamic acids are also described, e.g. trichlor benzyl diethyl dithiocarbamate. The additives described are more effective and more chemically stable than the corresponding Cl-free compounds and are not corrosive. Most of them are freely soluble in lubricating oils, and concentrates containing up to 50 per cent or more of additive can be prepared. Seven per cent concentrations of these additives in a mineral lubricating oil of 10111 S.U. viscosity at 210 DEG F. gave film strengths of up to 365 lb. and 40 lb. in the standard S.A.E. and Alman testers respectively, while the viscosity increase at 210 DEG F. did not exceed 17 per cent after heating for 100 hours at 300 DEG F. in open beakers.ALSO:Chloraralkyl esters of thio acids are obtained by reacting a chloraralkyl chloride with an alkali metal salt of the thio acid and separating the salt split out in the formation of the desired ester. Thus, di-(chloraralkyl) trithiocarbonates are prepared by first reacting sodium sulphide and carbon disulphide in methanol solution, then refluxing the solution with the chloraralkyl chloride, removing the solvent by distillation under vacuum and the sodium chloride by washing with water. Mono-(chloraralky) alkyl trithiocarbonates are prepared by first reacting the alkyl mercaptan with ethanol and caustic soda, followed by refluxing with the chloraralkyl chloride and purifying as above. Alternatively, the chloraralkyl chloride may be reacted with a methanol solution of sodium trithiocarbonate and the product, after removal of the solvent, dissolved in benzene to facilitate washing with water. O-ethyl-S-chloraralkyl monothiocarbonates are prepared by reacting the chloraralkyl chloride with a solution of Bender's salt in ethanol, pouring the mixture into an excess of water and extracting the oil with a volatile solvent such as ether from which it is subsequently recovered. The chloraralkyl esters of benzothiolic acid are prepared by reacting the chloraralkyl chloride with a suspension of the potassium salt of benzothiolic acid in ethanol. The latter salt was prepared by reacting benzoyl chloride with an alcoholic solution of potassium hydrogen sulphide, precipitating the benzothiolic acid formed by the addition of hydrochloric acid, and neutralizing with aqueous potassium hydroxide. Mono-(chloraralkyl) dialkyl dithiocarbamates are prepared by reacting the chloraralkyl chloride with an ethanol solution of the diethyl amine salt of the dialkyl dithiocarbamic acid prepared by reacting diethyl amine with a solution of carbon disulphide in the alkyl alcohol, e.g. ethanol. After removal of the solvent the reaction product was washed with water, dilute hydrochloric acid and finally water again, preferably with the aid of a water immiscible solvent. After removal of the latter the residue was dried and filtered through a bed of adsorbtive decolorising clay. Chlor phenyl ethyl, ethyl xanthates are prepared by the chloride of the chlor phenyl ethyl benzene dissolved in acetone or ethanol with potassium ethyl xanthate at refluxing temperature. Examples of chloraralkyl esters of thio acids mentioned are di-(trichlor benzyl) trithio-carbonate, trichlor benzyl butyl trithiocarbonate, o-chlor benzyl butyl trithiocarbonate, di-(o-chlor benzyl) tritiocarbonate, o-ethyl s-trichlor benzyl-monothiocarbonate, trichlor benzyl diethyl dithiocarbamate, dichlor diethyl phenyl ethyl, ethyl xanthate, a -(2,4-dichlor phenyl) ethyl trithiocarbonate, di-(chlor ethyl phenyl ethyl) trithiocarbonate, di-(dichlorethyl phenyl ethyl) trithiocarbonate, di-(trichlor ethyl phenyl ethyl) trithiocarbonate, di-(tetrachlor ethyl phenyl ethyl) trithiocarbonate, the trichlor benzyl ester of benzothiolic acid, and trichlor phenyl ethyl, ethyl xanthate. Most or all of these products are oily liquids moderately to freely soluble in mineral (hydrocarbon) lubricating oils. The chloraralkyl chlorides were prepared by catalytic chlorination, using iron filings as catalyst for ring chlorination and exposure to ultra-violet light for chlorination of the side chains. Specification 604,388 is referred to.