GB989942A - Copolymers - Google Patents

Abstract

Oxthiolanes are prepared by reaction of mercaptoalkanols with aldehydes or aldehyde yielding compounds such as paraformaldehyde in the presence of an acid, e.g. a Lewis acid. In the preparation of 1,3-oxthiolane 390 g. mercaptoethanol, and 153 g. paraformaldehyde are heated in the presence of 0.05 to 5% of a strong acid, 200 ml. benzene added, water distilled off azeotropically and the remainder of solvents also distilled off. The residue is distilled off under normal pressure or in vacuo either with addition of 0.2 to 0.5% acid or after neutralization of the acid present. The crude product may be purified by treatment with potassium hydroxide or aluminium hydroxide and dried over metallic sodium.ALSO:A solid ternary copolymer of trioxane has recurring units consisting of -CH2-O groups interrupted by groups (a) of formula <FORM:0989942/C3/1> where R is hydrogen, alkyl or halo-alkyl groups of one to four carbon atoms, X is methylene, methylene ether, or methylene thioether radicals and n is 1, 2 or 3, and by groups (b) of formula <FORM:0989942/C3/2> where R is as above, X is methylene, oxymethylene, alkyl or haloalkyl substituted methylene or oxymethylene, the alkyl groups having one to four carbon atoms, n is 0, 1, 2 or 3 and m is 1, 2, 3 or 4, the amount of (a) and (b) groups in the copolymer being from 50 to 0.1% and the weight ratio of (a) to (b) being from 0.1 : 1 to 1 : 0.1. The copolymer may be prepared by cationic catalysis, e.g. with boron fluoride diethyl etherate, aryldiazonium fluorborates and other Lewis acids, in bulk (preferably) or in suspension or solution. Specified compounds of formula (a) are ethylene, propylene and butylene sulphide, tetrahydrothiophene, 1-3-oxthiolane, 2-methyl-1,3-oxthiolane, 1-3-dithiolane, 2 - methyl - 1 - 3 - dithiolane and 1 - 3 - dioxa - 6-thiacyclo-octane while specified compounds (b) are ethylene oxide, 1-4-dioxane, trimethylene oxide, tetramethylene oxide, 1-2-propylene oxide, 1-2- or 1-3-butylene oxide, epichlorhydrin, 2 - 2 - di - (chloroalkyl) - 1 - 3 - propylene oxide, 1-3-dioxolanes, diethylene glycol formal, dioxane, 1 - 3 - dioxa-cycloheptane, 1 - 3 - 5 - trioxacycloheptane, 1 - 3 - 6 - 9 - tetraoxacyclo undecane, pentacrythritol diformal and tetrahydrofuran. The copolymer may be heated alone, in suspension, solution or with alcohols in the presence of bases, to increase the thermal stability.