The Effect of Surfactants and β-Cyclodextrin on the Photooxidation of Stable Carbanions

• Published in: Bulletin of the Chemical Society of Japan Vol. 51; no. 11; pp. 3302 - 3306
• Main Authors: Yamada, Kazutoshi, Shigehiro, Kiyoshi, Tomizawa, Tetsuo, Iida, Hirotada
• Format: Journal Article
• Language: English
• Published: The Chemical Society of Japan 01.11.1978
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.51.3302

The micellar effect on the photochemistry of α-(4-hydroxyimino-2,5-cyclohexa-dienylidene)-α-phenylacetonitrile and its derivatives has been studied. 4-Nitrobenzophenone derivatives were obtained by the irradiation of ethanolic alkaline aqueous solutions of the oximes. 4-Nitrosobenzophenone derivatives formed as an intermediate were thermally oxidized to give the corresponding nitro compounds. The reaction was found to be the photochemical oxidation by singlet oxygen. The addition of an anionic surfactant (sodium dodecyl sulfate) and a nonionic surfactant (Tween #80) to the reaction solution scarcely changed the pKa values of oximes, whereas the addition of a cationic surfactant such as hexadodecyltrimethylammonium bromide (HTAB) caused a considerable decrease. This indicates that HTAB promotes the formation of a stable carbanion. The presence of HTAB enhanced the rate of photooxidation by a factor of 102. The catalytic effect becomes maximum at the pH value of the reaction solution near the pKa measured in the presence of HTAB or β-CDX.