Cobalt Substituted Keggin-Type Phosphotungstate, an Efficient Epoxidation Catalyst: Study on Kinetic Behavior as Well as Reaction Mechanism

Abstract

Keggin type undecatungstophospho(aqua)cobaltate (II) (Cs-PW₁₁Co) was synthesized by one step easy synthesis method and characterized in solution as well as solid by various spectral techniques. The catalytic activity of the isolated complex was evaluated for epoxidation of cis-cyclooctene under ambient temperature and pressure conditions. A detailed kinetic study was carried out for epoxidation of cyclooctene. The energy of activation was also determined from the Arrhenius plot. In the present study, the catalytic system is homogeneous; even then the catalyst was regenerated and reused. The active cobalt hydroperoxo intermediate was characterized in solution by UV-visible and ³¹P NMR and based upon this study, a probable reaction mechanism was proposed.

Keywords:

• cobalt substituted phosphotungstate
• cyclooctene
• epoxidation
• kinetics

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Funding

One of the authors, Ms. Pragati Shringarpure, is thankful to Council of Scientific and Industrial Research (CSIR New Delhi) for providing financial assistance.