GB580748A - Improvements in the manufacture of vinyl ethers - Google Patents

Abstract

Vinyl ethers, other than n-butyl vinyl ether, are prepared by contacting acetylene and an alcohol, other than n-butyl alcohol, with a potassium alkoxide dissolved or suspended in a medium consisting solely or mainly of a secondary or tertiary aromatic amine at a pressure not greater than 9 lbs./sq. in. and a temperature of about 150-250 DEG C. The reaction is preferably conducted in an oxygen - free atmosphere and in the presence of an N : N1 - diphenyl - p - phenylenediamine as antioxidant. The alkoxide used is preferably that of the alcohol undergoing reaction. In the examples: (1) a mixture of a solution of potassium in iso-butyl alcohol and ethyl aniline, together with a little N : N1-diphenyl-p-phenylenediamine is placed in a reaction tower fitted with a fractionating column, a stream of nitrogen being passed through the tower. The contents of the tower are heated and the nitrogen flow gradually replaced by a preheated mixture of iso-butyl alcohol vapour and acetylene under slight pressure. The reaction products pass into the fractionating column and an azeotrope containing mainly iso-butyl vinyl ether separated from unreacted iso-butyl alcohol which is recycled. The ether is purified by distilling over sodium. The process may be rendered continuous by replacing the catalyst as it becomes spent. (2) A solution of potassium in iso-butyl alcohol and diethylaniline with a little N : N1 - diphenyl - p - phenylenediamine, is added, in an atmosphere of nitrogen, to diethylaniline contained in a flask fitted with a stirrer and a stripping column. The contents of the flask are heated and the nitrogen flow replaced by acetylene and iso-butyl alcohol. Vinyl iso-butyl ether distils off. (3) Acetylene and tetrahydrofurfuryl alcohol are passed with vigorous agitation through a mixture of potassium dissolved in tetrahydrofurfuryl alcohol and diethylaniline. The product is fractionated and distilled over sodium. The resultant vinyl tetrahydrofurfuryl ether may be polymerized with stannic chloride dissolved in petrol or with boron trifluoride/acetic acid complex. (4) and (5) Vinyl ethyl and vinyl methyl ether are prepared respectively in the manner described in example 1, the solvents being diethylaniline and benzyl ethyl aniline respectively. The process can also be applied to, for example, the preparation of the vinyl ethers of propyl, isopropyl and tert. - butyl alcohols. Other specified amines which may be used as reaction media are methylaniline, dimethylaniline, diethyl o- and p-toluidines, benzylaniline and dibenzylaniline. Specification 579,675 is referred to.