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 225-285ºC, respectively. The reactions are first order in each reactant and the second-order rate constants are given by K₂ = 10^13.14exp(-112000/RT) for 1,l-dimethoxyethane and k₂ = 10^12.66exp(-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.