Kinetics of drug decomposition. Part 46. Photooxidation and photolysis of some perazine derivatives.

The rate and type of the photochemical degradation of perazine derivatives in acidic aqueous solutions depends upon the nature of the substituent at C2 atom. Free perazine degrades by two parallel reactions, namely a fast reversible first-order photooxidation and a slow zero-order photolysis. An introduction of the substituent in the C2 position results frequently in the elimination of one of these reactions.

Kinetics of drug decomposition. Part 47. Effect of substituents on photochemical stability of perazine derivatives.

A quantum yield phi of photooxidation of perazine derivatives estimated actinometrically and the pKa, values were used for the correlation with the substituent volumes. The Hammett type plots of phi= f(sigma) and phi= f(pKa10--pKa1) are discussed.