ELECTROCHEMISTRY OF S-TRIAZINE HERBICIDES - REDUCTION OF ATRAZINE ANDTERBUTYLAZINE IN AQUEOUS-SOLUTIONS

The electrochemical behavior of both herbicides is qualitatively simil ar. The two-electron reduction of atrazine (2-chloro-4-ethylamino 6-is opropylamino-1,3,5-triazine) proceeds only in acidic media where the p receding protonation takes place (pK = 1.44). In solutions of higher p H (2-4) the observed reduction current is kinetically controlled by pr otonation and the estimated value of the protonation rate constant is k(r) = 2400 +/- 400 mol(-1) 1 s(-1). The products of reduction were id entified by large-scale electrolysis followed by GC-MS analysis. The e lectron transfer reaction causes cleavage of the Cl atom and loss of t he ethyl group yielding the respective products in the ratio approxima tely 4:1. The electrochemical properties of terbutylazine are characte rized by the protonation constant pK = 2.37 and rate constant k(r) = 1 900 +/- 200 mol(-1) 1 s(-1).