Chemistry of acetylenic ethers ‐XXXI. A simplified procedure for the preparation of ethyl β‐chlorovinyl ether

Ethyl β‐chlorovinyl ether can be obtained easily from chloroacetaldehyde diethylacetal by heating with potassium pyrosulphate. The product contains a large proportion of the cis ‐isomer. The required acetal has been prepared from paraldehyde, alcohol and chlorine. The method has been applied also for the synthesis of butyl β‐chlorovinyl ether. Ethyl β‐chlorovinyl ether can also be prepared continuously by passing chloroacetal vapour at 220‐230° over pumice impregnated with 4% of potassium bisulphate. The conversion of trans ‐ into cis ethyl β‐chlorovinyl ether by irradiation in the presence of traces of bromine is described.