The Strecker reaction — an examination in terms of no-barrier theory

Abstract

For those examples of the Strecker reaction where information about both rate and equilibrium is available, we have been able to calculate rate constants for the addition of cyanide ion to the iminium ion by the no-barrier theory (NBT) approach. Both experimental and calculated values are for reaction in aqueous solution. Only for the reactions of benzaldehyde with benzyl or allyl amines and HCN are the equilibrium constants and rate constants for the final, rate-determining, step directly available from the literature. For the reactions of acetone with ammonia, methylamine, or dimethylamine and HCN rate constants for the retro-Strecker cleavage and the equilibrium constants for the overall Strecker reaction have been reported. These equilibrium constants, combined with equilibrium constants for iminium ion formation, which can be extracted from information in the literature, allow calculation of the equilibrium constants for the final step of these Strecker reactions. No-barrier theory has already been applied to carbonyl additions, including cyanohydrin formation; this report provides further evidence for the generality of this approach for calculating rate constants without using any kinetic information.Key words: Strecker reaction, rate constant, equilibrium constant, no-barrier theory, computation.