GB839561A - Preparation of thioethers - Google Patents

Abstract

In a process for making vinyl thioethers from acetylene and thiols free of acidic hydrogen and of olefinic or acetylenic saturation, in the presence of a strongly basic alkali metal compound as catalyst and an inert organic solvent capable of dissolving at least 18 volumes of acetylene at 0 DEG C. and 1 atmosphere, the acetylene is absorbed at elevated pressure and a temperature not exceeding 14 DEG C. and the mixture is then heated to 100-200 DEG C. under pressure sufficient to keep the acetylene dissolved in the liquid phase. It is desirable to have a saturated liquid alcohol present; this may be the abovementioned inert solvent or may be additional thereto, and in the latter case it may be the thiol reactant when it contains an alcoholic substituent. Other suitable inert solvents are certain ethers (including cyclic ethers), acetals and glycol and polyglycol ethers, and N-alkylpyrrolidones; these are such as dissolve at least 20 volumes of acetylene at 0 DEG C. and 14 at 10 DEG C. (at 1 atmosphere). The alcohol mentioned above can be an alkanol, an alkoxyalkanol or a hydroxyalkyl glycol or polyglycol ether; a mercaptoalkanol serves both as alcohol and as thiol reactant. The catalyst may be an alkali metal oxide, hydroxide, cyanide, sulphide, alcoholate or mercaptide; the alkali metal itself may be used to generate the catalyst. The amount of catalyst is usually 1-10% of the thiol but may be up to the equivalent amount especially when the reactant is ethane-1 : 2-dithiol. The acetylene can be diluted with an inert gas. Suitable thiols are R(SH)n, where n is 1 or 2 and R is alkyl, cycloalkyl, aralkyl or aryl (or the corresponding divalent radical) optionally p subtiituted e.g. by hydroxy, amino, ether, thioether, ester, amide or heterocyclic groups; acidic hydrogen and unsaturation must be absent. Examples are given where R is methyl, ethyl, isopropyl, iso-, s-, and t-butyl, 2-ethylhexyl, decyl, n- and t-dodecyl, tetradecyl, octadecyl, b -hydroxyethyl, carbethoxymethyl, b - aminoethyl, phenyl, o-aminophenyl, benzyl, phenoxyethyl, cyclohexyl, tetrahydrofurfuryl, thenyl, ethylene, trimethylene, tetramethylene, pentamethylene and p-xylylene. Other suitable thiols are mentioned in which R is alkyl, hydroxyalkyl, alkoxyalkyl (including polyglycol derivatives), alkylthioalkyl, aminoalkyl (which may be N-substituted and in which the N-atom may be cyclic), cyanoalkyl, alkoxycarbonylalkyl (which may be substituted in the esterifying group), aminocarbonylalkyl (optionally N-substituted), cycloalkyl, cycloalkylalkyl, aryl, haloaryl, hydroxyaryl, aminoaryl, aralkyl, phenoxyalkyl, heterocyclylalkyl, benzthiazolyl, alkylene, hydroxyalkylene, oxybisalkyl or arylenebisalkyl. Specification 837,802 also is referred to.