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.
2â5 Although heterogeneous acids and bases are known to catalyze this reaction, limitations like low selectivity and/or low stability can limit their scope.
6â8 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.
References:
(1) van der Waal, J. C.; Rigutto, M. S.; van Bekkum, H. Appl. Catal. A Gen. 1998, 167 (2), 331â342.
(2) Tang, B.; Dai, W.; Wu, G.; Guan, N.; Li, L.; Hunger, M. ACS Catal. 2014, 4 (8), 2801-2810.
(3) Kahandal, S. S.; Kale, S. R.; Disale, S. T.; Jayaram, R. V. Catal. Sci. Technol. 2012, 2, 1493-1499.
(4) Dhakshinamoorthy, A.; Alvaro, M.; Garcia, H. Chem. - A Eur. J. 2010, 16 (28), 8530â8536.
(5) Zhu, X.; Venkatasubbaiah, K.; Weck, M.; Jones, C. W. J. Mol. Catal. A Chem. 2010, 329 (1â2), 1â6.
(6) Brunelli, N. A.; Long, W.; Venkatasubbaiah, K.; Jones, C. W. Top. Catal. 2012, 55, 432â438.
(7) Takeuchi, H.; Kitajima, K.; Yamamato, Y.; Mizuno, K. J. Chem. Soc. Perkin Trans. 2 1993, 199â203.
(8) Feng, Y.; Lydon, M. E.; Jones, C. W. ChemCatChem 2013, 5 (12), 3636â3643.
