Diaquabis(L-phenylalaninato)nickel(II) Encapsulated in Zeolite: An Efficient Heterogeneous Catalyst System for the Oxidation of Cyclohexene, Toluene and Ethyl Benzene

Massomeh Ghorbanloo,Nahid Shahbakhsh,Somayeh Ghamari,Seik Weng Ng

doi:10.5935/0103-5053.20140194

Abstract

L-Phenylalanine reacts with nickel-exchanged zeolite Y to form diaquabis(L-phenylalaninato)nickel(II), which is encapsulated in the pores of the zeolite. In this zeolite-encapsulated form, the nickel derivative functions as an efficient catalyst when cyclohexene, toluene and ethyl benzene are oxidized by hydrogen peroxide in the presence of sodium bicarbonate (as co-catalyst). The catalyst was readily recovered from the reaction mixture, and it could be re-used for other three runs without noticeable loss of activity. The heterogeneous catalyst exhibited significantly higher activity and selectivity compared with diaquabis(L-phenylalaninato)nickel(II) itself.

Highlights

The conversion of hydrocarbons in the presence of peroxides as oxidants to oxygenated derivatives such as, for example, alcohols, aldehydes/ketones and carboxylic acids exemplifies a catalytic process that has been extensively studied owing to the importance of the products as reactants in industrial processes.[1]
For heterogeneous catalysts in particular, one strategy for improving the stability involves encapsulation of the catalyst in zeolites; other strategies have the catalysts grafted onto polymers or bound onto MCM-41 silica.[3]
In continuation of our previous studies on the oxidation of a range of organic substrates catalyzed by transition metal complexes,[7,8,9,10,11] we report the use of diaquabis(Lphenylalaninato)nickel and diaquabis(L-phenylalaninato) nickel encapsulated in zeolite as catalyst systems for the oxidation of cyclohexene, toluene and ethyl benzene in the presence of hydrogen peroxide/sodium bicarbonate

Summary

Introduction

The conversion of hydrocarbons in the presence of peroxides as oxidants to oxygenated derivatives such as, for example, alcohols, aldehydes/ketones and carboxylic acids exemplifies a catalytic process that has been extensively studied owing to the importance of the products as reactants in industrial processes.[1]. In continuation of our previous studies on the oxidation of a range of organic substrates catalyzed by transition metal complexes,[7,8,9,10,11] we report the use of diaquabis(Lphenylalaninato)nickel and diaquabis(L-phenylalaninato) nickel encapsulated in zeolite as catalyst systems for the oxidation of cyclohexene, toluene and ethyl benzene in the presence of hydrogen peroxide/sodium bicarbonate.

Results

Conclusion