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.
encapsulated catalyst; zeolite; heterogeneous; hydrogen peroxide; co-catalyst
