Gas-phase decompositions of 1,1-dimethoxyethane and 1,1-diethoxyethane catalysed by hydrogen chloride

Abstract

The hydrogen-chloride-catalysed, gas-phase decompositions of 1,l-dimethoxyethane and 1,l-diethoxy- ethane to alkyl vinyl ethers and an alcohol have been studied over the temperature ranges 254-322 and 225-285�C, respectively. The reactions are first order in each reactant and the second-order rate constants are given by K2 = 1013.14exp(-112000/RT) for 1,l-dimethoxyethane and k2 = 1012.66exp(-96200/RT) for 1,l-diethoxyethane with k2 in s-l ml mol-1 and R in J K-1 mol-1. Substituent effects and the relative effectiveness of hydrogen chloride and hydrogen bromide as catalysts are consistent with those described previously for HX-catalysed alcohol and ether decompositions.