α-PINENE OXIDE ISOMERIZATION: Role of zeolite structure and acidity in selective synthesis of campholenic aldehyde

Martina Stekrova, Martin Kubu, Mariya Shamzhy, Zuzana Musilova, Jiří Čejka

Index: 10.1039/C8CY00371H

Full Text: HTML

Abstract

MWW-type zeolites with different textural properties, namely MCM-22, MCM-36, MCM-56, and MCM-49, were synthesized and tested in selective preparation of campholenic aldehyde by isomerization of α-pinene oxide. Commercial zeolites USY, Beta, and ZSM-5 were compared. The physico-chemical properties of studied zeolites were correlated with their catalytic performance in isomerization of α-pinene oxide carried out either in toluene as a solvent at 70 °C or in N,N-dimethylacetamide at 140 °C. α-Pinene oxide isomerizes easily in the presence of acids and therefore, high conversions were achieved over commercial as well as synthesized MWW catalysts. Higher selectivities to campholenic aldehyde were achieved over MWW catalysts in basic N,N-dimethylacetamide while non-basic toluene enhanced formation of desired aldehyde over all commercial zeolites. The highest selectivity to desired aldehyde was achieved over MCM-22 in reaction performed in N,N-dimethylacetamide at 140 °C being 83 % at total conversion of α-pinene oxide. This is the best result achieved competing with homogenous acids (ZnBr2) and metal-organic frameworks.