First determination of an activation volume for the osmium-catalyzed dihydroxylation of an alkene

Abstract

The rate constants for the dihydroxylation of (E)-ethyl cinnamate with osmium tetroxide in toluene were determined at atmospheric and high pressure indicating a slight acceleration by high-pressure. The volume of activation was determined to be –12 ± 2 cm³ mol^–1 for this transformation. This relatively small negative value can not be explained with a simple [3 + 2]-mechanism for which a significantly more negative value should be expected.