The Photo-Chemical Decomposition of Acetone at 3130A

The photo-chemical decomposition of gaseous acetone in light of 3130A has been investigated at 26°C under conditions of high acetone pressure and low absorbed light intensities. The ratio C2H6/CO has been found to decrease substantially below unity at sufficiently low absorbed intensities, under which condition methane has been found as a major product, exceeding the amount of ethane at very low intensities. A kinetic analysis of these data has shown that only a free radical process for the formation of ethane and methane suffices to explain the experimental observations. The energy of activation for the reaction of a methyl radical with an acetone molecule to form methane has been determined as E = 6.5 kcal./mole.