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

An ion trap mass spectrometer has been used to measure the ion/molecule rea ction rate constants for three reactions involving acetonitrile and primary alcohols. The values obtained for the reaction between CH3CNH+ and CH3OH l eading to the products CH3CNCH3+ was 4.6 +/- 0.2 X 10(-11) cm(3) molecule(- 1) s(-1). The reaction between CH3CNH+ and CH3CH2OH (to give CH3CNCH2CH3+ H2O) proceeds with a rate constant of 3.9 +/- 0.4 X 10(-10) cm(3) molecule (-1) s(-1), and that between CH3CH2CH2OH2+ + CH3CN has a value of 2.1 +/- 0 .4 x 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 in itially formed proton-bound dimer in each case. (C) 2001 Elsevier Science B .V.