Synthesis of dialkyl ethers by decarboxylation of dialkyl carbonates

The decarboxylation reaction of dialkyl carbonates to give their related ethers was investigated. The reaction was carried out at atmospheric pressure and in the presence of hydrotalcite or basic alumina as catalysts without any solvent. The influence of several reaction parameters on the selectivity was studied (e.g. temperature, amount of catalyst, substrate concentration, solvent). The stability of the catalyst was also investigated. The experimental data for the decarboxylation confirmed that this reaction is complicated by competitive processes, such as dismutation and, in one case, pyrolysis. The results obtained show that in the presence of hydrotalcite as a catalyst, symmetrical dialkyl ethers can be synthesised with yields up to 80%. Dissymmetrical ethers (i.e. methyl alkyl ethers) can be produced with yields up to 80% at high temperature (250 ◦C). The catalyst proved to be fully recyclable in all cases studied, except for the carbonate containing n-octyl moiety.