Mechanism of the Benzophenone-Sensitized Photolysis of <i>O</i>-Benzoyl-<i>N</i>-(1-naphthoyl)-<i>N</i>-phenylhydroxylamine in Cationic Micellar Media

• Tsuyoshi Kaneko

  Department of Applied Chemistry, Faculty of Technology, Kanagawa UniversityKanagawa-ku, Yokohama 221-8686

• Tatsuya Tokue

  Department of Applied Chemistry, Faculty of Technology, Kanagawa UniversityKanagawa-ku, Yokohama 221-8686

• Kanji Kubo

  Institute of Advanced Material Study, 86, Kyushu UniversityKasuga-koen, Kasuga, Fukuoka 816-0811

• Tadamitsu Sakurai

  Department of Applied Chemistry, Faculty of Technology, Kanagawa UniversityKanagawa-ku, Yokohama 221-8686

抄録

The benzophenone-sensitized photolysis of the title hydroxylamine (1) in hexadecyltrimethylammonium chloride (HTAC) micelles was found to give benzoyloxy(2,3)- and phenyl(4,5)-migrated products, along with fragmentation products, 1-naphthanilide (6) and benzoic acid (7), which were obtained exclusively from the sensitized reaction in organic media. An analysis of the effects of added benzyl alcohol on the quantum yields for the reaction in HTAC micelles showed that the benzoyloxy-migrated products are derived from the amidyl-benzoyloxyl radical pair (that is present at the micellar surface), whereas the amidyl-phenyl radical pair (that is penetrated deeply into the micellar interior) is responsible for appearance of the phenyl-rearranged products. This effect of benzyl alcohol also confirmed that the hydrogen abstraction of the amidyl and benzoyloxyl radicals takes place in competition with the spin inversion of these triplet radicals. These interpretations were substantiated by the finding that the critical micelle concentration for HTAC is reduced in the presence of benzyl alcohol, but that the alcohol exerts only its very small effect on the aggregation number. On the other hand, the use of hexadecyltrimethylammonium bromide (HTAB) micelles instead of HTAC resulted in 2 and 3 in negligible quantum yields with increased quantum yields for the formation of 4—7. This intriguing result was explained in terms of (1) much less efffective hydrogen-bonding solvation of the assumed hot triplet radical pair in the more hydrophobic HTAB micellar surface as well as (2) heavy-atom effects on the intersystem crossing from the singlet amidyl-benzoyloxyl radical pair to the triplet one. Based on the quantum yields for the triplet-sensitized photolysis of 1 in HTAC–HTAB mixed micelles, it was demonstrated that the hydrogen-bonding solvation described above plays a major role in suppressing the benzoyloxy photorearrangement reaction in the HTAB micelle cage.

収録刊行物

• Bulletin of the Chemical Society of Japan

  Bulletin of the Chemical Society of Japan 72 (12), 2771-2780, 1999-12-01

  Oxford University Press (OUP)

キーワード

• General Chemistry

詳細情報

• CRID: 1360846644034746880
• NII論文ID: 130004058260
• DOI: 10.1246/bcsj.72.2771
• ISSN: 13480634
• ISSN: 00092673
• Web Site: https://academic.oup.com/bcsj/article-pdf/72/12/2771/56199978/bcsj.72.2771.pdf
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