Solvent-induced selectivity in α-pinene oxide isomerization catalyzed by Fe-modified zeolite beta

Abstract

α-Pinene oxide rearrangement to important product—trans-carveol and campholenic aldehyde in the presence of zeolite beta modified by various amount of iron (0.625–20 wt%) was studied. The amount of iron influenced initial reaction rate and time for 50% conversion. The initial reaction rate decreased with decreasing amount of iron therefore with decreasing acidity. On the other side, the highest conversion achieved after 180 min was in the case of material modified by 5 wt% of iron. The selectivity was only slightly influenced by the iron amount, but very important was the influence of used solvent on product distribution. Large variety of solvents was used in this reaction (toluene, acetonitrile, 1,4-dioxane, acetone, N,N-dimethylformamide, N,N- dimethylacetamide, dimethyl sulfoxide). Using strongly basic polar solvents (e.g., dimethyl sulfoxide) the main product in the reaction mixture was trans-carveol and using low-basic solvents (e.g. toluene) it was campholenic aldehyde. It was shown that the product distribution may be induced by used solvent.