Epoxides are versatile chemical intermediates that can be conveniently synthesized from alkenes.
1 Opening of the epoxide ring can be achieved with various nucleophiles like water, alcohols, amines, and thiols yielding synthetically important di-substituted compounds.
2–5 Although heterogeneous acids and bases are known to catalyze this reaction, limitations like low selectivity and/or low stability can limit their scope.
6–8 In this work we have studied silica-based Lewis acidic catalysts with varying pore-sizes and Lewis acid-site strength. We report that these catalysts can selectively open the epoxide ring using alcohols under mild conditions for different systems including epichlorohydrin-methanol. Systematic investigations of the effect of acid site strength, temperature, and pore-confinement of these materials revealed that these factors affect the catalytic activity but not the regioselectivity. In case of straight chain mono-functional epoxides, the regioselectivity increases with an increase in nucleophile size. Overall, we have studied catalytic performance and reusability of different silica-based Lewis acidic catalysts for epoxide ring opening with alcohols.
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