Thermodynamic Properties of the Acetyl Radical and Bond Dissociation Energies in Aliphatic Carbonyl Compounds

Abstract

Photoionization mass spectrometry was used to study the thermodynamic properties of the acetyl radical and to determine bond energies in acetone and biacetyl. From measured appearance potentials of CH₃CO⁺ and by the use of thermodynamic cycles, the following bond energies were determined: D₀(CH₃–CO)=0.49±0.03 eV, D₀(CH₃CO–CH₃)=3.34±0.06 eV and D₀(CH₃CO–COCH₃)=2.84±0.06 eV. D₀(CH₃CO–H) is calculated to be 3.69±0.06 eV. ΔH_f°(CH₃CO) is calculated to be —0.28±0.06 eV.