Reactions of Alkoxy Radicals. I. Photolysis of Methyl Acetate

The photolysis of methyl acetate has been investigated in the vapor phase over the temperature range 29 to 217°C at varying light intensities and initial pressures. The main primary step is a split of the ester molecule into CH₃CO and CH₃O radicals. The following reactions involving methoxy radicals have been established: $${\mathrm{CH}}_3\mathrm{O}+{\mathrm{CH}}_3\to {\mathrm{CH}}_2\mathrm{O}+{\mathrm{CH}}_4$$ $${\mathrm{CH}}_3\mathrm{O}+{\mathrm{CH}}_3\to {\mathrm{CH}}_3{\mathrm{OCH}}_3$$ $${\mathrm{CH}}_3\mathrm{O}+{\mathrm{CH}}_3{\mathrm{COOCH}}_3\to {\mathrm{CH}}_3\mathrm{OH}+{\mathrm{CH}}_2{\mathrm{COOCH}}_3.$$ As activation energies for reactions (A) and (C) were obtained E_A≤1.5 kcal and E_C≃4.5 kcal. No information could be obtained regarding the extent to which reaction (D) occurred. $$\text{2\hspace{0.17em}}{\mathrm{CH}}_3\mathrm{O}\to {\mathrm{CH}}_3\mathrm{OH}+{\mathrm{CH}}_2\mathrm{O}.$$ An activation energy of 10 kcal was obtained for the abstraction of a hydrogen atom from methyl acetate by methyl radicals.