Triazine herbicides ametryne

Oxidation of triazine herbicides with chlorine and chlorine dioxide has been widely studied [105-108]. In the case of sulfur-containing triazines, oxidation occurs mainly via cleavage of the weakened R-S-CH3 bond rather than by addition of chlorine. Reactions of S-triazines with chlorine are faster than with chlorine dioxide, and form sulfoxide, sulfone, and a sulfone hydrolysis product. Chlorination with chlorine dioxide only produced sulfoxide [108]. Lopez et al. identified the formation of sulfonate esters during the chlorination of ametryn and terbutryn [106, 107]. Triazine DBFs identified by Brix et al. exhibited higher toxicities than the parent compounds [105]. Similar to triazines, clethodim, a cyclohexanedione herbicide, is oxidized by hypochlorite and chloramines to clethodim sulfoxide and then to sulfone [109]. 

Ametryn and other triazines herbicides in tap water NS MIP-based cartridge < 1 ug/L. However, low recovery (10-40%) Ferrer and Barcelo, 1999... 

Most producers concentrated their production on the major triazines (e.g., atrazine, simazine, terbuthylazine, ametryn, and terbutryn). The producers of triazine herbicides through the 1990s are presented in Table 3.1, and producers since 2000 are listed in Table 3.2. 

The triazine herbicides can be divided into four different structural classes chlorotriazines, methylthiotriazines, methoxytriazines, and atypical or asymmetrical triazines. The chlorotriazine group includes atrazine, simazine, pro-pazine, terbuthylazine, and cyanazine. The methylthiotriazine group includes ametryn, prometryn, and terbutryn. The methoxytriazine group will include prometon and secbumeton. Hexazinone and metribuzin were chosen to represent the atypical triazine group. The plant metabolism of the most researched member of each triazine group will be discussed in detail to cover all major biological and chemical transformations reported in the literature. 

Furthermore, the triazine herbicides have freed operators from much of the laborious burden of weed control, enabling them to manage other resources to maximize returns of both agricultural and milling operations. Since atrazine and ametryn were introduced, the genetic potentials of sugarcane cultivars have been more fully realized because the soil tillage and water losses have been reduced. 

The sugarcane industry in the United States and worldwide is highly dependent on the continued availability of triazine herbicides. In the United States, growers use reduced quantities of atrazine by applying it as a band over the row. Ametryn is strategically important as a postemergence treatment. The loss of any of the most essential sugarcane... 

Ametryn, another triazine herbicide, was previously used for weed control in citrus. This herbicide first appeared in recommendations in 1979 for control of broadleaf weeds, annual grasses, and some perennial grasses. Ametryn was recommended at use rates of 3.6-7.2kg a.i./ha, with a maximum of 5.4kg a.i./ha for both shallow, poorly drained flatwood soils (soils having more organic matter and clay) and bedded groves (trees planted on raised beds). It was recommended that ametryn should not be applied to trees less than 2 years old. Between 1984 and 1988 the application rates were increased to 7.2-10.8kg a.i./ha, with the annual rate not to exceed 13.6kg a.i./ha, and with lower rates... 

Wang, Y.-S., J.-R. Duh, Y.-F. Liang, and Y.-L. Chen (1995). Dissipation of three s-triazine herbicides atrazine, simazine, and ametryn in subtropical soils. Bull. Environ. Contam. Toxicol., 55 351-358. 

Worldwide there have been a total of 20 commercialized triazine herbicides. Of the 20 triazines, 7 are currently registered for land use within the United States ametryn, atrazine, metribuzin, prometryn, simazine, terbutryn, and prometon. For purposes of this discussion, only dietary estimates for the 5 most widely used domestic triazines are presented since the USEPA revoked cyanazine tolerances in 2004, prometon is not used for food crops and terbutryn has very limited use. Additionally, propazine was used under USEPA Section 18 registrations in the 1990s, and in 2007 was registered for weed control in sorghum (USEPA, 2007). 

Hydrolases are also induced by xenobiotics in insects, but to a lesser extent, by juvenile hormone, juvenoids, triazine herbicides (e.g., atrazine and ametryn), and allelochemicals (e.g., terpenoids, indoles, and flavonoids) (Yu and Hsu, 1985 Yu, 2004). 

Larson et al. (1992b) discovered that ferric salts in weakly acidic solution were very significant promoters of photodecomposition of the triazine herbicides atra-zine, ametryn, prometon, and prometryn (Figure 6.21). As described earlier (Equa-... 

Takeuchi and co-workers (18) coupled combinatorial techniques with molecular imprinted polymers to develop sensors for triazine herbicides. The library consisted of a 7 x 7 array containing different fractions of monomers methacrylic acid (MAA) and 2-(trifluoromethyl)acrylic acid (TFMAA) with constant concentrations of the imprint molecules ametryn or atrazine. After UV-initiated polymerization, the products from the sensor library were characterized by HPLC measurement of herbicide concentration. The receptor efficiency was observed to vary with monomer type the atrazine receptor efficiency increased with MAA composition and the ametryn receptor was enhanced by increased fractions of TFMAA. Although only monomer concentration was varied in the hbraries, the authors conclude that the CM synthetic approach would be usefiil in analyzing other variables such as solvent, cross-linking agent, and polymerization conditions to produce optimum molecularly imprinted polymer sensors. 

Ureides (e.g., diuron, linuron) and triazines (e.g., atrazine, simazine, ametryne) all act as inhibitors of photosynthesis and are applied to soil (see Figure 14.1 for structures). They are toxic to seedling weeds, which they can absorb from the soil. Some of them (e.g., simazine) have very low water solubility and, consequently, are persistent and relatively immobile in soil (see Chapter 4, Section 4.3, which also mentions the question of depth selection when these soil-acting herbicides are used for selective weed control). 

Alkylthiotriazines. In our laboratory we have studied the metabolic fate of 2-(4-ethylamino-6-methylthio- -triazin-2-ylamino)-2-methylpropionitrile (cyanatryn, 1, Fig. 1). This compound is a member of a class of herbicidal -triazines which also includes ametryne, prometryne and terbutryne. We were interested to note ( ) that two of the major metabolites of cyanatryn were the mercapturic acids 2-[A-ethylamino-6-(N-acetylcysteinyl)- -triazin-2-ylamino]-2-methylpropionitrTle (2.1) and its N-de-ethyl derivative (2.2) (Fig. 2). This pathway had not hitherto been reported for this class of compound. 

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