Heat of formation of hydroxymethyl

Threshold photoionization mass spectrometry has been used to measure the appearance energy for the formation of CH 2 OH + from methanol. A value of 708.5±0.8 kJ-mol -1 is obtained for the 298 K cationic heat of formation, which results in a corresponding heat of formation for the hydroxymethyl radical of -18.9±1.0 kJ mol -1 . The discrepancy between this value and the significantly higher heat of formation obtained from a kinetic study of the reaction of CH 2 OH with HBr and HI is discussed and partly resolved. An absolute proton affinity for formaldehyde of 712.9±1.0 kJ mol -1 is derived