The mechanism of hydrogenolysis and isomerization of oxacycloalkanes on metals -: XV.: Transformation of ethyl- and vinyloxirane on Cu-SiO2

The isomerization and hydrogenolysis of vinyloxirane and, for comparison, those of ethyloxirane were studied on a Cu-SiO2, catalyst at 373 K in a recirculation reactor, at various hydrogen pressures and in the presence of deuterium. It was established that in the case of ethyloxirane, the dominating reactions are deoxygenation associated with the formation of 1-butene and isomerization resulting in the formation of butanal. In the case of vinyloxirane, the enlargement of the oxirane ring to a five-membered ring also takes place in addition to deoxygenation and isomerization. Olefins are formed on Cu(0) while isomerization occurs on copper-copper oxide interfaces. The experimental results allow the identification of the probable reaction pathways leading to the formation of the individual products. (C) 1998 Elsevier Science B.V. All rights reserved.