SIFT studies of the reactions of H 3O +, NO + and O 2+ with several ethers

Abstract

We report the results of a selected ion flow tube (SIFT) study of the reactions of H 3O +, NO + and O 2 + with some 10 ethers, M. We assume that all the exothermic proton transfer reactions of H 3O + with all the ether molecules occur at the collision rate, i.e. the rate coefficients, k, are equal to k c, then it is seen that the k for most of the NO + and O 2 + reactions also are equal to or close to k c. The major ionic products of the H 3O + reactions are unusually complicated compared to the reactions of these reactant ions with many ketones, alcohols, aldehydes and carboxylic acids in which the products are predominantly MH + and (MH 2O) + ions (water molecule elimination). In these ether reactions, water elimination is not observed, but rather MH + and ions resulting from the elimination of alcohol and hydrocarbon molecules are the common products. The NO + reactions mostly proceed via hydride ion (H +) transfer producing (MH) + ions and an HNO molecule, with parallel alkyl radical ion, R-, abstraction (producing (MR) +) ions (and RNO molecules) being evident in two of the reactions and aikoxide ion, RO +, abstraction (producing hydrocarbon ions and RONO molecules) in two of the other reactions. The NO +/anisole reaction proceeds exclusively via charge transfer, this being allowed because of the low ionization energy of anisole. The O 2 + reactions proceed by dissociative charge transfer with the production of two or more ionic fragments of the parent molecular ion, the different isomeric forms of these ether molecules resulting in different product ions.