Reactions of Free Radicals with Aldehydes. II. The Reactions of Methyl Radicals with Propionaldehyde

The reaction of radicals derived from the thermal decomposition of di-t-butyl peroxide with propionaldehyde in the gas phase has been studied. The gaseous products were carbon monoxide, methane, ethane, propane, butane, and ethylene. A mechanism to account for the induced chain decomposition and product formation involving H atom abstraction by radicals and radical decomposition, combination and disproportionation is given. The energetics of H atom abstraction by methyl and ethyl were similar and lead to an activation energy of about 7.5 kcal/mole and a steric factor of about 10—3. These values are in good agreement with those found for H atom abstraction from acetaldehyde. Evidence is presented that H atom abstraction takes place with the carbonyl attached H for both acetaldehyde and propionaldehyde.