Energetics of the dehydration of nitrile-alcohol proton-bound dimers from ion/molecule reaction kinetics

Abstract

An ion trap mass spectrometer has been used to measure the ion/molecule reaction rate constants for three reactions involving acetonitrile and primary alcohols. The values obtained for the reaction between CH 3CNH + and CH 3OH leading to the products CH 3CNCH 3 + was 4.6 ± 0.2 × 10 −11 cm 3 molecule −1 s −1. The reaction between CH 3CNH + and CH 3CH 2OH (to give CH 3CNCH 2CH 3 + + H 2O) proceeds with a rate constant of 3.9 ± 0.4 × 10 −10 cm 3 molecule −1 s −1, and that between CH 3CH 2CH 2OH 2 + + CH 3CN has a value of 2.1 ± 0.4 × 10 −10 cm 3 molecule −1 s −1. These values for the rate constants have been used to extract the activation energy for isomerization of the initially formed proton-bound dimer in each case.