Surface photoreactions of 2-benzoylcyclopentanones: Silica gel surface as a possible field bringing out the latent reactivity of dispersed molecules
摘要:
Irradiation of 2-benzoyl- and 2-(p-methylbenzoyl)cyclopentanone (la and Ib), which have the lowest n,pi* excited states and showed no photoreactivities in inert solvents, neat or in the solid state, gave two types of products on a silica gel surface; one arose from the cleavage of the C-C bond a to the benzoyl group and the other arose from the cyclopentanone C-1-C-2 bond cleavage. Analysis of Langmuir adsorption isotherm of la by a non-linear least-squares method revealed that 7.9 x 10(-4) mot of 1a was spread as a monomolecular layer over 1 g of silica gel, The photoreactivity of 1a on the surface was very sensitive to the coverage; the efficiency of disappearance of la decreased monotonically from 100% at low coverages to zero at nearly 100% coverage. Close packing of molecules of 1 on the surface diminished the photoreactivity. A silica gel surface provided a possible dispersion field for bringing out the latent photoreactivity of 1.
Irradiation of 2-benzoyl- and 2-(p-methylbenzoyl)cyclopentanone (la and Ib), which have the lowest n,pi* excited states and showed no photoreactivities in inert solvents, neat or in the solid state, gave two types of products on a silica gel surface; one arose from the cleavage of the C-C bond a to the benzoyl group and the other arose from the cyclopentanone C-1-C-2 bond cleavage. Analysis of Langmuir adsorption isotherm of la by a non-linear least-squares method revealed that 7.9 x 10(-4) mot of 1a was spread as a monomolecular layer over 1 g of silica gel, The photoreactivity of 1a on the surface was very sensitive to the coverage; the efficiency of disappearance of la decreased monotonically from 100% at low coverages to zero at nearly 100% coverage. Close packing of molecules of 1 on the surface diminished the photoreactivity. A silica gel surface provided a possible dispersion field for bringing out the latent photoreactivity of 1.