This paper presents polarographic [direct current and differential pulse (DP)] studies of the electroreduction of the s-triazine derivatives prometryne [2-methylthio-4,6-di(isopropylamino)-1,3,5-triazine], desmetryne [2-methylthio-4-methylamino-6-isopropylamino-1,3,5-triazine], and terbutryne [(2-methylthio-4-ethylamino-6-terbutylamino)-1,3,5-triazine] on mercury electrodes. The studies are performed in the acidity range 2.25 M
H2SO4
to pH 6.5. Above this last pH value, no signals were obtained. In DP polarography, two main reduction peaks were observed, accompanied by a prepeak, at less negative potentials, due to the adsorption of the herbicides on the electrode. The main peaks corresponded to two-electron irreversible reduction processes, at pH values higher than the protonation pK of the triazine ring (ca. 4). In this pH range, the protonation of the triazine ring precedes the reduction process, this reaction being also responsible for the observed decrease in limiting current. In strongly acidic media
false(normalpH
This paper presents polarographic ͑dc and differential pulse͒ and voltammetric ͑linear-sweep cyclic voltammetry͒ studies of the electroreduction of the s-triazine derivative 2,4-diamino-1,3,5-triazine on mercury electrodes. The studies are performed in the acidity range 2.25 M H 2 SO 4 to pH 11. Above this last pH value no signals were obtained. In both dc DP polarography, two reduction waves/peaks were observed. The overall process corresponded to a two-electron irreversible reduction. For the first wave, the proposed reduction mechanism consists of the two-electron reduction of the reactant protonated in the heterocyclic N3 nitrogen, with reversible electron transfers. The rate-determining step ͑rds͒ is a protonation placed after such transfers. At pH values lower than the protonation pK, the protonation reaction takes place prior to the reduction. For the second wave, the unprotonated reactant is reduced and the rds is a protonation placed between the two reversible one-electron transfers. At high pH values, dissociation of the amino group causes the disappearance of the wave.
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