GB838020A - Preparation of vinyl ethers - Google Patents

Abstract

In a process for making vinyl others from acety lene and alcohols free of acidic hydrogen in the presence of a strongly basic alkali metal compound as catalyst and 10-100% of 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 pressures and a temperature not exceeding 14 DEG C., and the mixture is then heated to 160-250 DEG C. under pressure sufficient to keep the acetylene dissolved in the liquid phase. The strongly basic catalyst may be an alkali metal oxide, hydroxide, alkoxide, cyanide or sulphide thereof, an alkoxide formed in situ being preferred; the alkali metal itself may be used to generate the catalyst. Suitable solvents are certain ethers (including cyclic ethers), acetals and glycol and polyglycol ethers and N-alkyl-pyrrolidones: 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 ratio of solvent to alcohol should be 1 : 10 to 1 : 1 by weight, and preferably 1 : 7 to 1 : 1.5. The acetylene may if desired by diluted with an inert gas, the pressure used for absorption being preferably 9.4-30 atmospheres and the temperature +10 to -30 DEG C. Examples show the preparation of vinyl ethers of ethanol, n-butanol, t-butanol, n-octanol, a mixture of C10-C14-C18 alcohols, cyclohexanol, benzyl alcohol, allyl alcohol, p-(t-octyl)-phenoxyethanol, ethanolamine and its N-methyl, N : N dimethyl and N-aminoethyl derivatives, 3-amino-1-propanol, ethylene glycol (giving monoand di-ethers) and b -vinyloxyethanol. In general, R may be alkyl, alkenyl, cycloalkyl, cycloalkenyl, aralkyl or aralkenyl and many suitable alcohols are mentioned, some of which are substituted by alkoxy, alkylthio, chlorine, amino or heterocyclic groups, or combinations of such groups. 2-Methyl-1 : 3-dioxolane is a by-product when ethylene glycol is used. The acetylene solvents used in the examples are dimethoxyethane, methylal and triethylene glycol dimethyl ether. Other suitable solvents are listed. The preferred range of reaction temperatures is 180-210 DEG C.