SIFT studies of the reactions of H3O+, NO+ and O2+ with a series of aldehydes and ketones

The results are reported of a selected ion flow tube (SIFT) study of the rate coefficients and the ionic products of the reactions of H3O+, NO+ and O-2(+) with some 11 aldehydes and nine ketones including the structural isomers of some. We assume that the 20 exothermic H3O+ proton transfer reactions proceed at the collisional rate and on this basis the large majority of the remaining 40 reactions included in this study also proceed close to the collisional rate. A variety of reaction processes are seen to occur. The H3O+ reactions proceed via proton transfer which for the ketones produces the protonated molecules only but which in the aldehyde reactions H,O elimination from the protonated molecule also occurs. The NO+ reactions with the aldehydes proceed largely via the process of hydride ion transfer whereas ion-molecule association is the dominant process in the NO+/ketone reactions with charge transfer also evident in some cases. The O-2(+) reactions with both the aldehydes and ketones proceed largely via charge transfer which in all reactions is partially dissociative producing several ionic products for the more polyatomic reactant molecules. Different products are observed in the reactions of O-2(+) with some of the structural isomers. (C) 1997 Elsevier Science B.V.