Unimolecular reactions methyl isocyanide isomerization

Our interest in thermally activated unimolecular reactions is in the change of kuni with pressure from the high to the zero pressure limit, and in the pressure dependence of the isotope effect over that range. One particularly interesting study carried out by Rabinovitch and Schneider (reading list) focused on the isomerization of methyl isocyanide, CH3NC, to methyl cyanide, CH3CN... 

CH3NC — CH3CN has also been carried out, the principal object being the interpretation of the transition state. This particular tautomerism has also been the subject of an investigation in which experiments have been made to assess the importance of radical chain effects in the thermally induced reaction. It is concluded that there is no reason to doubt the fact that the isomerization of methyl isocyanide is an excellent test for the theory of unimolecular reactions. 

As a particular example of an unimolecular reaction, we consider the isomerization of methyl isocyanide to acetonitrile, which has been extensively studied by Schneider and Rabinovitch [18]. The reaction is... 

The experiments that seem to show the most promise in studying unimolecular dynamics are the ones in which a molecule is vibration-ally excited by one photon absorption. In very elegant experiments Berry and coworkers have studied the intramolecular and unimolecular dynamics of benzene,methyl isocyanide,and allyl isocyanide containing 4-7 quanta of C-H stretch excitation. For the isomerization of allyl isocyanide nonstatistical state-selected effects were observed. These one photon absorption experiments suggest that state-selected behavior may be prevalent in many unimolecular reactions. However, it is apparent that the sensitivity of the experiments should be improved so that excitation and unimolecular reaction occur in a collision-free environment, thus ensuring the elimination of intermolecular effects that may wash out some of the state-selective characteristics. 

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See also in sourсe #XX -- [ , ]

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