Nickel acetate catalyzed autoxidation of benzoin
- Creators
- Hammond, George S.
- Wu, Chin-Hua S.
Abstract
The autoxidation of benzoin in methanol catalyzed by nickel acetate is first order in each of benzoin and the catalyst and independent of the partial pressure of oxygen. The stoichiometry and product analysis demonstrate that benzoin reacts with oxygen to give benzil and hydrogen peroxide. A primary isotope effect of k_B/k_D = 7 has been observed. The rates of oxidation, relative to benzoin, of 4,4'-dichloro-, 4,4'-dimethyl-, and 4,4'-dimethoxybenzoin were respectively 2.4, 0.40, and 0.21. We suggest that the reaction involves equilibration of nickel acetate with a nickel acetate-benzoin complex. The rate-limiting step of the reaction involves abstraction of an α-hydrogen atom of the benzoin by an acetoxy group. Some intermediate must then react very rapidly with oxygen. Substituent effects indicate that in the slow step some net negative charge is introduced into the substrate group.
Additional Information
© 1973 American Chemical Society. Received July 7, 1973. This work was supported by a grant from the National Science Foundation. We are indebted to Professor Harry B. Gray for his helpful discussion. The technical assistance of Mr. Steve Hammond for some polarographic oxygen monitoring experiments is also acknowledged.Additional details
- Eprint ID
- 55388
- DOI
- 10.1021/ja00806a001
- Resolver ID
- CaltechAUTHORS:20150302-082326764
- NSF
- Created
-
2015-03-03Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Other Numbering System Name
- Caltech Arthur Amos Noyes Laboratory
- Other Numbering System Identifier
- 4755