Kinetics of drug decomposition. Part 37. Kinetics of autoxidation of narcotine in aqueous solutions.

The overall apparent first-order rate constants for the reaction of autoxidation of Narcotine (NC) - k1 and Cotarnine (CT) - k2 and the rate constants for autoxidation of the protonated (ks) and undissociated (kb) forms have been determined. The kinetic equation for the reaction of autoxidation at constant concentration of NC, CT and the atmospheric oxygen depending on the pH of the reaction medium has been established as: k1 = ks([H+]/([H+]+K'a))+kb(K'a/([H+]+K'a), k2=(ks[H+]+K'a))+kb (K'a/([H+]+K'a) (1+1+1/kt+1K)). The following thermodynamic parameters for the rate constants ks and kb have been calculated: deltaH not equal to, log A and deltaS not equal to.