Simazine photolysis

Direct photolysis of aqueous solutions of the 2-chloro-.v-iriaz.ine herbicides (atrazine, simazine, propazine) proceeds via excitation of the triazine molecule, followed mainly by dechlorination and hydroxylation to form the corresponding hydroxytriazine (Pape and Zabik, 1970 Khan and Schnitzer, 1978 Chan et al, 1992 Lai et al, 1995 Schmitt et al, 1995 Sanlaville et al, 1997 Torrents et al, 1997 Texier et al, 1999b Hequet et al, 2001). This observation - plus the fact that when 2-chloro-v-triazine herbicides are photolyzed in methanol, ethanol, and n-butanol, the respective 2-alkoxy derivatives are formed - indicates a mechanism involving photochemical solvolysis rather than the involvement of hydroxyl radicals. This conclusion is supported by the fact that the rate of oxidation of atrazine was unaffected by the presence of either bicarbonate ion (Beltran et al, 1993) or ferf-butanol (Torrents et al, 1997), both strong hydroxyl radical scavengers. 

CAAT), as well as the formation of cyanuric acid (OOOT or G-28251). Analogous products (CBAT or G-26379, CAET, OBET or GS-23158, OBAT, OAET, OAAT) were formed when an aqueous solution of terbuthylazine (CBET) was irradiated at 254 nm (Sanlaville et al., 1997). Direct photolysis (254nm) of an aqueous solution of simazine (CEET) resulted in the formation of hydroxysimazine (OEET or G-30414), as well as its dealkylated analog (OEAT) (Lai et al., 1995) (Table 23.2). 

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