HEATS OF FORMATION OF ACETYL HALIDES AND OF ACETYL RADICAL

Heats of hydrolysis of acetyl chloride, bromide, and iodide have been redetermined calorimetrically, and vapor pressures of the halides have been measured over moderate temperature ranges in order to determine heats of vaporization and heats of formation of the liquid and vapor species. In conjunction with kinetic data, the heat of formation of the acetyl radical has been determined which, together with the results of other experiments, places the value for ΔHf° (CH3CO, 298°K) at -5.8 ± 0.4 kcal/mol and firmly establishes a number of controversial bond dissociation energies.