THE GAS PHASE ASSOCIATION OF LEWIS ACIDS AND BASES. II. N(CH3)3 AND NH(CH3)2 IN COMPETITION FOR BF3,

A detailed analysis is presented of the rate laws expected for Lewis acid-base gas phase association reactions at pressures above several mm Hg. It is shown that in a competive system B2 and B3 competing for A the ratio of association rate constants, k3k2, is given by AB3AB2B2B3, irrespective of the relative efficiencies for stabilization of the vibrationally excited AB3 and AB2 by internal energy conversion vs energy transfer to the ambient gas. However, if the latter process were to dominate, the measured k3k2 would depend on the nature of the ambient gas. An experimental procedure was developed for measuring the relative amounts of salt produced in a competitive system, based on IR analyses of acetonitrile solutions of the mixed salts. This procedure is particularly applicable to systems in which the residual gases are preferentially absorbed in the solids produced. Data on the CH33N - CH32HN BF3 system are presented. The results show that at room temperature the ratio of association rate constants, k3k2 0.89 0.17, over the range 3 to 43 mm Hg total pressure. This ratio rose slightly to 0.95 at about 0.6 mm Hg, the lowest pressure studied. Author