GB1312822A - Polymercaptans - Google Patents

Abstract

1312822 Polymercaptans CIBA GEIGY (UK) Ltd 30 Dec 1970 [5 Feb 1970] 59580/71 Divided out of 1312821 Heading C3R Polymercaptans containing at least two -SH groups per molecule and suitable for use as curing agents or flexibilizers for epoxy resins, are produced by the esterification of a substance having at least two alcoholic hydroxyl groups per molecule and containing a repeating unit of the formula in which m is an integer of 4-6, and in each unit at least (m + 2) of the R's denote hydrogen the remainder being hydrogen, methyl or ethyl with a monomercaptocarboxylic acid, preferably a monomercapto mono- or di-carboxylic acid. The substance having at least two alcoholic hydroxyl groups per molecule may have the formula in which n is a positive integer, r a positive integer of at least 2 and G is a nitrogen atom in which case r equals 3, a group NR<SP>2</SP> in which R<SP>2</SP> is hydrogen on a monovalent organic radical in which case r equals 2 or the residue containing at least two carbon atoms after removal of r active hydrogen atoms of an organic compound originally having at least r alcoholic and/or phenolic hydroxyl groups. Preferred monomeroapto carboxylic acids are 2-mercaptobutyric, #-mercapto undecylic, #-mercapto stearic, o-mercapto benzoic, thioglycollic, 2- mercapto propionic and 3-mercapto propionic acids, thiomalic, 4 - mercapto - 3,6 - endomethylenecyclohexane - 1,2 - dicarboxylic acid, 2- mercapto adipic acid, 2-mercapto sebacic acid and 2-mercaptopimelic acid. The reaction may be effected by heating together the alcohol and acid in an inert solvent, e.g. toluene, xylene, trichloroethylene or perchloroethylene, in an inert atmosphere, e.g. nitrogen, in the presence of a strong acid catalyst, e.g. toluene-p-sulphonic acid or 50% sulphuric acid. In the examples a diol based on #-caprolactone or the reaction product of glycerol and #-caprolactone is reacted with thioglycollic acid or 3-mercaptopropionic acid in the presence of toluene-psulphonic acid and perchloroethylene under nitrogen.