Oxidation of benzoin to benzil and of p-substituted benzyl alcohol to the corresponding benzaldehyde catalyzed by iron(II) thiolate complexes. A proposed reaction mechanism
✍ Scribed by Wei-Yin Sun; Norikazu Ueyama; Akira Nakamura
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- French
- Weight
- 823 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
The catalync p-benzoqumone or au oxldaaon of benzoin to bennl was camed out m the presence of Pen&-o-xyl)#-(o-xyl = o-xylene-a. a'-&thlolate) or [Fen(S+Bu)&-m a ratlo [benzomlficatalyst] = 20/l m DMF at 25 'C Under such mild reacnon condmons, the Fe(II) thiolate complex exhibited high catalync activity In the reacuon catalyzed by [Fen&-o-xyl)d2-, 64% and 93% of benzom was oxldlzed to benzll in 25 h by air and p-benzoqumone, respectively In the an oxidation of benzyl alcohol catalyzed by [Fe"&-o-xyl)212-, benzaldehyde was formed speclfically without formation of benzolc acid Furthermore, p-subsntuent effect (Cl > H > OMe) was found m the catalytic air oxldatlon of p-subsntuted benzyl alcohol The catalync oxidation 1s first order with respect to each of substrate and the catalyst at mmal stage A reacaon mechanism was proposed and the rate-determmmg step 1s at the release of the methme hydrogen as a proton winch 1s based on the kmetlc Isotope effect (kH/ko was 4 3 by p-benzoqmnone oxldatlon and 5 0 by au oxtdation, respectively) andp-substnuent effect of substrate m the presence of [Fen&-o-xyl)#-w -Y SUN et al