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Surface photoreactions of 2‐benzoylcyclopentanones: Silica gel surface as a possible field bringing out the latent reactivity of dispersed molecules
Author(s) -
Hasegawa Tadashi,
Imase Yoshihiro,
Imada Manabu,
Kumakura Kazushige,
Yoshioka Michikazu
Publication year - 1996
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199610)9:10<677::aid-poc838>3.0.co;2-n
Subject(s) - chemistry , cyclopentanone , silica gel , adsorption , molecule , reactivity (psychology) , inert , cleavage (geology) , photochemistry , dispersion (optics) , crystallography , organic chemistry , catalysis , medicine , alternative medicine , pathology , engineering , physics , optics , geotechnical engineering , fracture (geology)
Irradiation of 2‐benzoyl‐ and 2‐( p ‐methylbenzoyl)cyclopentanone (1a and 1b), which have the lowest n ,π* 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(SINGLE BOND)C bond α to the benzoyl group and the other arose from the cyclopentanone C‐1(SINGLE BOND)C‐2 bond cleavage. Analysis of Langmuir adsorption isotherm of la by a non‐linear least‐squares method revealed that 7·9 × 10 ‐4 mol of la was spread as a monomolecular layer over 1 g of silica gel. The photoreactivity of la 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.