Collect. Czech. Chem. Commun.
1995, 60, 2028-2038
https://doi.org/10.1135/cccc19952028
Study of the Electrochemically Initiated Cyanomethylation of Azomethines by Means of the MNDO and AM1 Semiempirical Methods
Jaromír Toušeka, Jaro Komendaa and Ulrich Hessb
a Institute of Theoretical and Physical Chemistry, Masaryk University, 611 37 Brno, Czech Republic
b Institute of Pharmacy, Humboldt University, D-13086 Berlin, Germany
Abstract
The semiempirical methods (MNDO and AM1) have been used in the quantum chemical study of electrochemically initiated cyanomethylation of azomethines. Reaction steps leading to the main product of the studied reaction, β-aminonitrile, have been described. The stationary points on the reaction path have been found and the activation enthalpies of reaction steps have been determined. Three possible mechanisms for the abstraction of a proton from acetonitrile have been described (by azomethine radical anion, by β-aminonitrile anion, and by hydrogenated azomethine anion). At the MNDO level, the abstraction of a proton by azomethine radical anion has the highest activation enthalpy (∆H = 197 kJ mol-1) and the abstraction of a proton by hydrogenated azomethine anion has the lowest activation enthalpy (∆H = 146 kJ mol-1). The activation enthalpy of the next reaction step (the reaction of acetonitrile anion with azomethine) is low compared to the activation enthalpies of the previous reation steps (∆H= 12 kJ mol-1).
