Herbicides containing Halogens

The destruction of bulk malathion has been carried out in Na/NH3 at Commodore s Marengo, OH facility in a 1200-L unit in 100-lb quantities. Near-stoichiometric quantities of sodium were able to destroy the malathion. The levels of malathion in the treated material were nondetectable. Most bulk samples of organic pesticides and herbicides containing halogens, phosphorous, or sulfur are amenable to reductive destruction using Na/ NH3. Many waste streams were produced when manufacturing pesticides were remediated using solvated electron reductions. 

Combustion in an incinerator is the only practical way to deal with many waste streams.This is particularly true of solid and concentrated wastes and toxic wastes such as those containing halogenated hydrocarbons, pesticides, herbicides, etc. Many of the toxic substances encountered resist biological degradation and persist in the natural environment for a long period of time. Unless they are in dilute aqueous solution, the most effective treatment is usually incineration. 

There is only one simple anion commonly found in soil, and that is chloride (Cl ). Chloride is an essential nutrient for plants but is typically present in sufficiently high concentrations that deficiencies are never observed. If other halogens are present, they will also be present as simple anions. Most soils do contain small amounts of bromide as the second most common simple anion. In some cases, significant levels of fluoride and iodide may be present, although this is rare. These anions are generally soluble in water and tend to exist as the simple anion. However, they can combine with other components and exist as other species. For instance, halogens are present in organic compounds such as solvents, insecticides, and herbicides, which can be soil contaminants. There are also other nonionic species of these elements that may be present [20],... 

Some good inhibitors of the Hill reaction, however, do not contain the carbonyl oxygen-nitrogen moiety. Examples are the dinitroanilines, diphenylethers, 2,4-dinitrophenols, halogenated benzonitriles, and pyridinols. Hence, the postulates proposed are not all inclusive. Three of these herbicides are phenols. Under physiological pH s, the molecules can be expected to be ionized, and it may be the ionized form of the molecule that binds to the receptor. 

A survey of the new ISO provisionally approved active ingredients for modern crop protection available in the time frame 2000-2006 (February) shows that around 74% of them are halogen-substituted (Br, I < Cl, Cl/F < F). In this time, approximately four times more halogen-containing insecticides acaricides and fungicides, as well as two times more herbicides, were approved than non-halogenated active ingredients. 

Halogen-containing Triazinylsulfonylurea Herbicides Exchange of the ortho-chloro... 

Table 35.14 Halogen-containing triazinylsulfonylurea herbicides (87-93) (see Fig. 35.22 for the basic structure).

Halogen-containing Pyrimidinylsulfonylurea Herbicides The flrst halogenated member of this subclass is chlorimuron-ethyl (96 soya beans and peanuts, 9-13... 

Fig. 35.24. Halogen-containing pyrimidinylsulfonyl herbicides halosulfuron-methyl (101) and imazosulfuron (102).

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