Photooxidation of methyl ethyl ketone vapor

The photochemical reaction between methyl ethyl ketone and oxygen has been studied at 150 °C with light of 3 130 A. Measurement of the quantum yields of the major products of the reaction indicates the chain nature of the reaction, the length of the chain decreasing with increase in time. Extrapolation of quantum yields of products to zero time allows the evaluation of several relative rate constants and at least an indication of the individual radical sources of the observed products. It is shown that abstraction of hydrogen atoms from the methyl group takes place at least at a quarter the rate of abstraction of a secondary hydrogen from the ethyl group at 150 °C. In the initial products the ethyl group gives mainly acetaldehyde or perpropionic acid, the methyl group gives formaldehyde and methanol, and the carbonyl group gives carbon dioxide and perpropionic acid with a little carbon monoxide.