Gas phase negative ion chemistry of alkylchloroformates. A convenient method for bimolecular generation of chloride ion adducts and determination of chloride affinities from ion cyclotron resonance thermal equilibrium measurements

Abstract

A new method for production of chloride ion adducts, MCl−, via a sequence of bimolecular ion molecule reactions involving chloroformate esters is described. These reactions have been used in trapped-ion ion cyclotron resonance thermal equilibrium studies to determine the relative chloride ion affinities of twenty compounds with Cl− binding energies in the range 10–25 kcal mol−1. The present results are found to be in good agreement with chloride affinities obtained by other methods. The resulting chloride affinity scale establishes a convenient framework for the systematic investigation of effects of molecular structure and chemical properties on the binding energy of Cl− to both Lewis and Brønsted acids.