GB1005460A - New process for the manufacture of organic disulphides - Google Patents

Abstract

Organic disulphides, particularly dialkyl and diaryl disulphides, are obtained by reacting sulphur with one or more mercaptans in the presence of an aqueous solution of an amine in a quantity sufficient to absorb the hydrogen sulphide which is formed during the reaction. The reaction mixture preferably contains about 2 mols. of mercaptan and about 0.75 atoms of sulphur, while the preferred quantity of amine is at least one equivalent per 2 mols. of mercaptan. The solution of amine hydrosulphide formed is subsequently dissociated in order to regenerate the hydrogen sulphide and the amine, the latter being used again in the sulphidation of the mercaptan. The regenerated H2S is subjected to oxidation in known manner to regenerate sulphur. The preferred amines are those having a boiling point above 100 DEG C., especially the alkanolamines. The treatment of the mercaptan with sulphur is preferably carried out at a temperature between 0 DEG and 50 DEG C. and may be effected at a pressure higher than atmospheric pressure, e.g. at 1 to 15 atm. The amine is generally used in aqueous solution with a concentration between 10 and 80%, preferably about 50%. The process can be carried out continuously or intermittently and the sulphur may be introduced into the reaction mixture as a fine powder in the form of a suspension in the amine solution. The reaction yields an aqueous phase and an organic phase, this latter comprising the disulphide product. The aqueous phase, formed by the amine solution containing the combined H2S and a small quantity of dissolved mercaptan is distilled with a view to its dissociation into H2S and amine intended for recycling and for recovery of the mercaptan. Specified disulphides are: dimethyl, diethyl, dipropyl, diisopropyl, di-n-butyl, diisobutyl, dihexyl, dioctyl, dinonyl, didecyl, didodecyl, diphenyl, ditolyl, diethylphenyl, discylyl, ditolylnenzyl, diethylbenzyl and dinaphthyl disulphides.