Kinetics of the Oxygenation of Unsaturated Organics with Singlet Oxygen Generated from H2O2 by a Heterogeneous Molybdenum Catalyst
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- 作者：Bert F. Sels ; Dirk E. De Vos ; Pierre A. Jacobs
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：May 30, 2007
- 年：2007
- 卷：129
- 期：21
- 页码：6916 - 6926
- 全文大小：261K
- 年卷期：v.129,no.21(May 30, 2007)
- ISSN：1520-5126
文摘
A heterogeneous catalyst containing MoO42- exchanged on layered double hydroxides(Mo-LDHs) is used to produce 1O2 from H2O2, and with this dark 1O2, unsaturated hydrocarbons are oxidizedin allylic peroxides. The oxidation kinetics are studied in detail and are compared with the kinetics of oxidationby 1O2, formed from H2O2 by a homogeneous catalyst. A model is proposed for the heterogeneouslycatalyzed 1O2 generation and peroxide formation. The model divides the reaction suspension in twocompartments: (1) the intralamellar and intragranular zones of the LDH catalyst; (2) the bulk solution. The2-compartment model correctly predicts the oxidant efficiency and peroxide yield for a series of olefinperoxidation reactions. 1O2 is generated at a high rate by the heterogeneous catalyst, but somewhat more1O2 is lost by quenching with the heterogeneous catalyst than using the homogeneous catalyst. Quenchingoccurs mainly as a result of collision with the LDH hydroxyl surface, as is evidenced by using LDH supportscontaining strong 1O2 deactivators such as Ni2+. A total of 15 organic substrates were peroxidized on apreparative scale using the best Mo-LDH catalyst under optimal conditions.