Kou Hatada

Type L zeolites as selective catalysts for the ring transformation of cyclic ethers into cyclic imines

Abstract Type L zeolites were found to be highly selective catalysts for the ring transformation of cyclic ethers into cyclic imines. With use of the hydrogen form (HL), pyrrolidine was obtained in a 56% yield with the selectivity of 90% at 350 °C by the reaction of tetrahydrofuran and ammonia. There is no sign of catalyst deactivation within 8 hr. Kinetic study revealed that the reaction rate was the first order with respect to partial pressure of ammonia and was independent of partial pressure of tetrahydrofuran. Theinfluences of decationation and the kinds of metal cations in the zeolite on the catalytic behavior were examined, and the reaction mechanism and the origin of high selectivity were discussed. Type L zeolites are also effective catalysts for the conversion of tetrahydropyran into piperidine.

Ring transformation of tetrahydrofuran into pyrrolidine over synthetic zeolite

Abstract Synthetic zeolites were found to be effective catalysts for the ring transformation of tetrahydrofuran (THF) into pyrrolidine. With HY, the yield of pyrrolidine is 43% and the selectivity for it is over 80% at 335 °C. There is no sign of catalyst deactivation within 6 hr. The kinetic study was carried out with HY to obtain the following rate equation: r = k · K THF P THF · P NH 3 1 + K THF P THF The effect of degree of decationation of zeolite on the catalytic properties was examined and it is concluded that active centers are Bronsted sites formed at SII positions in the supercage. The reaction mechanism is also proposed.

Ring transformation of γ-butyrolactone into 2-pyrrolidinone over synthetic zeolites

Abstract Catalytic activities of synthetic zeolites for the ring transformation of γ-butyrolactone into 2-pyrrolidinone were compared in a flow reactor and CuY, HY, LiY, and NaY were found to have high activity. Alkaline earth forms of Y-zeolites lose their activity rapidly though their initial activities are high. For CuY, effects of the reaction temperature and the partial pressures of the reactants on the catalytic activity and the selectivity for 2-pyrrolidinone were examined. At 230 °–260 °C, selectivity of 80–90% is easily attained. The product, 2-pyrrolidinone, works as a strong poison for the catalysis. The role of metal cations in zeolites is discussed and the reaction mechanism is proposed.