Ketene: Ion chemistry and proton affinity

Abstract

The gas phase ion-chemistry of ketene has been examined using a Quadrupole Ion Store (QUISTOR) as an ion-molecule reaction chamber. The ion chemistry of ketene is remarkably similar to that of the primary aliphatic alcohols and mercaptans and is characterized by associative and eliminative reactions of ions with a labile proton attached to the electronegative atom. The rate coefficients for the disappearance of CH 2 −+ and CO −+ in ketene were found to be 3.8 ± 1 × 10 −10 and 3.2 ± 0.5 × 10 −11 cm 3 molecule −1 s −1, respectively. The proton affinity of ketene as determined by the bracketing technique was estimated to lie between the proton affinities of dimethyl ether and 2-propanol at a value of 807 ± 8 kJ mol −1.