PHOTOISOMERIZATION OF 3-BENZOYLACRYLATES ON A SILICA GEL SURFACE: EFFECT OF REACTION ENVIRONMENT ON SELECTIVITY

摘要

On irradiation on a dry silica gel surface, 2-(N, N-dialkylamino) ethyl 3-benzoylacrylates undergo selective E-Z isomerization. Competing processes, such as remote-hydrogen abstraction via a charge-transfer state, with the photoisomerization in solution are completely suppressed on the surface. The yield of the Z- from the E-isomer increases with increase in the coverage of the E-isomer on the surface, reaching a limiting value. Thermal isomerization of the Z- to the E-isomer occurs easily on the silica gel surface when the alkyl group on the nitrogen atom is small. Benzoylacrylates without any amino group also undergo selective photoisomerization.