Electrochemicalreduction of a herbicide metamitron (4-amino-3-mefhyl-6-phenyl-1,2,4-triazin-5(4H)-one) in buffered aqueous solutions occurs on the protonated 1,6-carbon-nitrogen double bond. The 2,3-double bond in the resulting 1,6-dihydrometamitron is electrochemically reduced at considerably more negative potentials. In reaction with borohydride the 2,3-double bond is reduced first. Reduction of
Metamitron (1) does not undergo hydrolysis at pH 1-8 and up to 5 M H(2)SO(4). The product of its two-electron reduction, 1, 6-dihydrometamitron (2), on the other hand, undergoes at pH <3 relatively fast hydrolysis. The dependence of the measured rate constant on acidity indicates that the completely protonated form (AH(2)(2+)) predominating in strongly acidic media undergoes hydrolysis slower than the species