Jp. Guthrie, PREDICTION OF RATE CONSTANTS FOR CYANOHYDRIN FORMATION USING EQUILIBRIUM-CONSTANTS AND DISTORTION ENERGIES, Journal of the American Chemical Society, 120(8), 1998, pp. 1688-1694
Rate constants for cyanohydrin formation in aqueous solution can be pr
edicted, with no use of kinetics information, by the application of a
simple model requiring only equilibrium constants and distortion energ
ies for the species involved in the reaction. The detailed model for c
yanohydrin formation involves two reaction coordinates: C-C bond forma
tion, which would lead to a cyanohydrin with an orthogonal geometry, a
nd conversion of the carbonyl center from sp(2) to sp(3). Allowance mu
st be made for the necessary desolvation of cyanide ion before C-C bon
d formation begins and for the initial partial desolvation of the newl
y formed cyanohydrin anion. The energies of the ''corner intermediates
'' can be calculated, and then the rest of the surface can be deduced
using an assumed interpolation formula. With distortion energies deriv
ed from semiempirical or ab initio molecular orbital calculations and
overall energy changes based on experimental equilibrium constants, an
d with the assumption of a quadratic dependence of energy on reaction
coordinates, the Literature data for rate constants for cyanohydrin fo
rmation in solution can be matched for a representative selection of c
ompounds spanning the reactivity range which has been studied.