GB770729A - Rust inhibiting compositions and concentrates containing thioether carboxylic acids - Google Patents

Abstract

In an example for the production of a branched chain C13 alkyl thioether acetic acid which may be used as a rust inhibitor in mineral lubricating oil compositions (see Group III) an olefinic polymer of propylene which may contain a small amount of butylene is fractionated to obtain a heart cut of substantially pure C12 olefin. This is subjected to the oxo process to form an aldehyde which is then hydrogenated to form the corresponding C13 oxo alcohol and the latter is then converted to the corresponding mercaptan by reaction with hydrogen bromide at 125 DEG C. to form the bromide which is then treated under reflux conditions, preferably in the presence of ethanol, with an alkali metal mercaptan, e.g. sodium or potassium mercaptan, to form the mercaptan. If desired, hydrogen chloride and zinc chloride may be used instead of hydrogen to form the chloride which is then treated as above. An aqueous solution of sodium hydroxide is then added slowly to the mercaptan diluted with isopropyl alcohol and a solution of monochloroacetic acid in water added slowly and the mixture acidified with concentrated hydrochloric acid to form tridecyl (C13 oxo) mercapto acetic acid. The tridecyl group is mainly tetra-methyl nonyl. It is stated that alkyl thioether acids of the general formula R-S-R1-COOH, in which R1 is a straight chain hydrocarbon group containing 1, 2 or 3 carbon atoms and R is a branched chain alkyl group containing from 13 to 16 carbon atoms, may be obtained by a similar process. Thus hexadecyl mercapto acetic acid may be obtained from pentapropylene via the oxo process as above. Other olefines which may be used in the oxo synthesis as a step in the production of the acids are tri-isobutylene and copolymers of propylene and butylenes which yield C13 to C16 oxo alcohols. Specification 645,434 is referred to.ALSO:A rust inhibiting composition or concentrate comprises a mineral oil and an acid of the general formula R.S.R1COOH where R is a branched chain alkyl group containing from 13 to 16 carbon atoms and which is derived from an oxo alcohol and where R1 is a straight chain saturated hydrocarbon group containing 1, 2 or 3 carbon atoms. Other additives may also be included in the composition, e.g. oiliness agents, extreme pressure additives, thickening agents, pour point depressors and detergents. The blends may suitably contain from 0.005 per cent to 0.20 per cent by weight of the acid or concentrates may be prepared containing about 20 per cent to about 60 per cent by weight of the acids in a mineral lubricating oil. In examples a branched chain tridecyl mercapto acetic acid in which the tridecyl group corresponds to an oxo alcohol derived from a C12 propylene polymer (see Group IV(b)) is dissolved in a solvent refined Mid-continent distillate of viscosity 45 S.U.S. at 210 DEG F. to form a 40 per cent concentrate which may be used to prepare blends, e.g. with steam turbine oils. Tables are given to show the effectiveness of the above thioether acid as a rust inhibitor in a phenol extracted Mid-Continent like stock and in a distillate fuel having a boiling range of 360 DEG to 642 DEG F. and a gravity of 34.6 A.P.I. Reference is also made to the use of a branched chain hexadecyl mercapto acetic acid in which the hexadecyl group corresponds to an oxo alcohol derived from a C15 olefine, predominately pentapropylene and a table is given to show that this acid and the above tridecyl mercapto acetic acid are completely miscible with a phenol extracted Mid-continent lubricating oil whilst lauryl- and cetylmercapto acetic acids are only slightly soluble. Specification 654,434 is referred to.