Reaction of C₂H^{{radical dot}+}₂ with CF₃COOC₂H₅, ClCH₂CN and CH₃PH: the bond energy D(C₂HH)

Reactions of C₂H^{{radical dot}+}₂ with methanol, chloroacetonitrile and ethyltrifluoroacetate were studied in a selected-ion flow tube in order to bracket the proton affinity of the C₂H^{{radical dot}} radial. The proton afinity PA(C₂H^{{radical dot}}) was measured as 181.6 ± 1 kcal mol^-1 at 298 K. A thermochemical cycle leads to the bond energy D₀ (C₂HH) = 129.3 ± 1 kcal mol^-1. This value is in good agreement with previously published data and corrects an ealier published value from this laboratory.