Ring-opening and dimerization reactions of methyl- and dimethyloxiranes onHZSM-5 and CuZSM-5 zeolites

Ring-opening and dimerization reactions of methyloxirane and cis- and trans -2,3-dimethyloxirane were studied on CuZSM-5, prepared by various methods, and HZSM-5 zeolites in a closed static recirculation reactor at 363 K in re ductive atmosphere. On these materials two main reaction types, ring-openin g and dimerization, could be observed. For methyloxirane the major transfor mation pathways were ring opening and dimerization, producing various dioxo lane and dioxane derivatives. In addition to these routes 2,3-dimethyloxira nes underwent deoxygenation and rearrangement as well. The activities and s electivities of the transformations toward these pathways were found to be significantly different depending on the stereochemistry of the substrates as well as the nature of the catalysts. Suggestions for the active sites an d transformation mechanisms are also offered. (C) 1999 Academic Press.