LOW-TEMPERATURE OXYGEN ATOM ADDITION TO OLEFINS .3. TRANSITION STATE AND REACTION WITH CIS- AND TRANS-2-BUTENES

The reaction of ground-state oxygen atoms O(3P), with either cis- or trans-2-butene at cryogenic temperatures produces cis- and trans-2,3-epoxybutane, 2-butanone, and isobutyraldehyde. Product ratios are different for the two 2-butenes. Two precursor states, one leading to the trans epoxide and 2-butanone, and the other to the cis epoxide and isobutyraldehyde, are implied by the constancy of the ratios trans-2,3-epoxybutane/2-butanone and cis-2,3-epoxybutane/isobutyraldehyde. A new transition state for the O atom-olefin reaction is proposed. A prediction based on the new transition state for the O atom reaction with 2-methyl-2-butene was consistent with the experimental finding.