title: Reactions of hydrated electrons with triazine derivatives in aqueous medium.
abstract: A study is made of the kinetics and mechanism of the reaction of radiolytically produced hydrated electron (e-(aq)) with some triazine derivatives [1,3,5-triazine (T), 2,4,6-trimethoxy-1,3,5-triazine (TMT), 2,4-dioxohexahydro-1,3,5-triazine (DHT), 6-chloro N-ethyl N-(1-methylethyl)-1,3,5-triazine 2,4-diamine (atrazine, AT), and cyanuric acid (CA)] in aqueous medium using pulse and steady-state radiolysis techniques. The second-order rate constants were determined from the pseudo first-order decay of e(-)(aq) in the presence of triazines at 720 nm, and the values obtained with T, TMT, AT, and CA are in the order of 10(9) dm(3) mol(-1) s(-1) and that of DHT was 10(8) dm(3) mol(-1) s(-1) at pH 6. The transient absorption spectra from the reaction of e(-)(aq) with T and TMT are characterized by their lambda(max) at 310 nm, and those of DHT and CA are around 280 and 290 nm, respectively. However, a very weak and featureless absorption spectrum is obtained from AT. On the basis of the spectral evidence and on the quantitative electron transfer from the transient intermediates to the oxidant, methyl viologen (MV(2+)), the intermediate radicals are assigned to N-protonated electron adducts (with the unpaired spin density at carbon) of triazines. The degradation profiles, monitored as the disappearance of parent triazine concentrations as a function of dose, obtained with AT, TMT, CA, and DHT, highlight the potential use of e-(aq) in the degradation of triazines.
authors.affiliation: School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686-560, India.
authors.forename: Rani
authors.initials: R
authors.lastname: Varghese
authors.forename: Hari
authors.initials: H
authors.lastname: Mohan
authors.forename: P
authors.initials: P
authors.lastname: Manoj
authors.forename: V M
authors.initials: VM
authors.lastname: Manoj
authors.forename: Usha K
authors.initials: UK
authors.lastname: Aravind
authors.forename: K
authors.initials: K
authors.lastname: Vandana
authors.forename: C T
authors.initials: CT
authors.lastname: Aravindakumar
mesh_terms: D004583:Electrons; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D011675:Pulse Radiolysis; D013057:Spectrum Analysis; D014227:Triazines / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D006540:Herbicides; D014227:Triazines; D014867:Water