Reaction of Oxygen Atoms, O(3P), with Ethylene in Liquid Nitrogen Solution

Abstract

The reaction of ground-state oxygen atoms, O(3P), with ethylene and ethylene-d4 in liquid nitrogen solution at 77° K has been studied. The major and perhaps the exclusive products are ethylene oxide and acetaldehyde. The ratio of acetaldehyde to ethylene oxide is 1.2 ± 0.1 for ethylene and 0.91 ± 0.09 for ethylene-d4. Much smaller amounts of formaldehyde and trace quantities of cyclopropane are also observed.The effect of the concentration of ethylene on the quantum yields of addition products was measured. A limiting quantum yield of oxygen atoms scavenged by ethylene to form the addition products was 0.12 + 0.01. The low quantum yield suggests an appreciable cage recombination of the ground-state oxygen atoms with the trace amounts of molecular oxygen present. The effect of the concentration of added oxygen on the product yields and the relative rate constant for the addition of O(3P) to molecular oxygen and to ethylene were determined. The ratio [Formula: see text] is 6.0 ± 1.0 and the relative rate constant for the addition of O(3P) to ethylene and to ethylene-d4, [Formula: see text], is 2.0 ± 0.1.The type of products formed and the isotope effects observed are discussed in terms of the mechanism of addition of O(3P) atoms to ethylene.