2,4,5-trichlorophenoxy-acetic

Ether Cle va.ge, This is commonly observed as the initial step in the metaboHsm of the phenoxy herbicides 2,4-D (1), (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T), and mecoprop (17). A wide variety of bacteria have been isolated which are able to catalyze this reaction (eq. 

Aroclor 1248, Aroclor 1254, and Aroclor 1260. Quantitation is by comparison of chromatograms with standard concentrations of pure compounds treated in an identical manner. The phenoxy acid herbicides (2,4-dichlorophenoxy)acetic acid (2,4-D), sUvex, and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) can be deterrnined by electron-capture detection after extraction and conversion to the methyl esters with BF.-methanol. The water sample must be acidified to pH <2 prior to extraction with chloroform. 

Hoffman, D.J. and W.C. Eastin, Jr. 1982. Effects of lindane, paraquat, toxaphene, and 2,4,5-trichlorophenoxy-acetic acid on mallard embryo development. Arch. Environ. Contam. Toxicol. 11 79-86. 

Acid herbicides such as 2,4 dichlorophenoxy acetic acid, 2,4,5-trichlorophenoxy acetic acid, 3,6-dichloropicolinic acid and other types of herbicides such as Dicamba, Dichloroprop, Picloram, Fenoprop, 2,3,6-TBA, Bromoxynil and Ioxynil are widely used in agriculture and are often formulated as mixtures. They may also be mixed in the spray tank or used in sequence, so it is likely that residues of more than one of these compounds may be present in the soil. 

Trichlorometafos, see Ronnel Trichloromethane, see Chloroform Trichloromethyl fluoride, see Trichlorofluoromethane Trichloromonofluoromethane, see Trichlorofluoromethane Trichloronitromethane, see Chloropicrin (2,4,5-Trichlorophenoxy)acetic acid, see 2,4,5-T Trichlorotrifluoroethane, see 1,1,2-Trichlorotrifluoroethane... 

Skurlatov, Y.I., Zepp, R.G., and Baughman, G.E. Photolysis rates of (2,4,5-trichlorophenoxy)acetic acid and 4-amino-3,5,6-trichloropicolinic acid in natural waters, J. Agric. Food Chem., 31(5) 1065-1071, 1983. 

Uses. Formerly used as an herbicide in brush control. Production was terminated in the United States in 1979 when the Environmental Protection Agency, in an emergency action, suspended all uses because of contamination with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In October 1983, all registrations for use of 2,4,5-trichlorophenoxy-acetic acid (2,4,5-T) were cancelled by the US Department of Agriculture because of concerns over the potential of dioxin contami-... 

Figure 8.9 The pH dependence of the /z-octanol-water distribution ratio of pentachlorophenol (PCP, pKj = 4.75), 4-chloro-a-(4-chlo-rophenyl) benzene acetic acid (DDA, pKb = 3.66), 2-methyl-4,6-dinitrophenol (DNOC, pKia = 4.46), and 2,4,5-trichlorophenoxy acetic acid (2,4,5-T, pKia = 2.83). (from Jafvert et al., 1990).

In Jamaica,302 no effect was found from (2,4-dichlorophenoxy)acetic acid, but positive responses were obtained from low rates of application (less than 0.009 lb. per acre) of (2,4,5-trichlorophenoxy)acetic acid and 2-(2,4,5 trichlorophenoxy)propionic acid. Louisiana sugarcane failed to respond to the low rates of (2,4-dichloro- or (2,4,5-trichloro-phenoxy)-acetic acid, but (2,4-dichlorophenoxy)acetic acid at one and three lb. per acre increased the sugar yield significantly at eight days, although not at 25 or 39 days.31 ... 

Application of ethylene-,4C to plants resulted in only a 2.4% conversion into soluble carbohydrates, 11% into ether-soluble materials, 6.9% into phytol, 31.7% into cellulose and lignin, and 9.6% into soluble protein and non-protein material, mainly phosphates. 9 Treatment of detached fruit (such as apples, bananas, peaches, figs, and pears) with synthetic auxins, especially (2,4,5-trichlorophenoxy) acetic acid, speeded up ripening, as indicated by color, taste, softness, and starch breakdown. 7 Other fruits have been similarly ripened, 8 and the treatments are effective both on climacteric and non-climacteric fruit. 

Chemicals Used. Chemicals used in this study were technical grade products or better, dissolved in xylene with 5% emulsifying agent. The chemicals used included an oil soluble red dye, Dino-seb (2-sec-butyl-4,6 dinitrophenol), pentachlorophenol (PCP), Isopropyl N-(3-chlorophenyl) carbamate (CIPC or Chlorpropham), Iso-octyl 2,4,5- trichlorophenoxy acetate (2,4,5-T), chlorpyrifos (0, 0-diethyl 0-(3,4,6-trichloro 2-pyridyl) - phosphorothioate), and Ronnel (0-dimethyl 0-2, 4,5-trichlorophenyl) phosphorothioate) for application as a spray. The emulsifiable concentrate was diluted in water comparable to 50 gallons of spray to contain the following amounts respectively 2 lbs. for chloropryifos 4 lbs. for 2,4,5-T 3 lbs. CIPC and 2 lbs. for PCP. 

The potential for environmental contamination continues to come from families of herbicides that have been used for years. The chlorophenoxy herbicides such as 2,4-D (2,4-dichlorophenoxy acetic acid) and 2,4,5-T (2,4,5-trichlorophenoxy-acetic acid) (Figure 5.1) are systemic acting compounds to control broadleaf plants and have been in use since the 1940s. The oral toxicities of these compounds are low. 

Dichloro-phenoxy acetic acid, 2,4,5- trichlorophenoxy acetic acid Herbicide derivatised to its methyl or 2-chlororethyl ester, then gas chromatography. 70 - 74% recovery [169]... 

D 2,4,5-T Silvex 2.4- DB MCPA Dichlorprop Dicamba (2,4-dichlorophenoxy) acetic acid (2,4,5-trichlorophenoxy) acetic acid (2,4,5-trichlorophenoxy)propionic acid 4-(2,4-dichlorophenoxy) butyric acid (4-chloro-2-methylphenoxy)acetic acid 2-(2,4-dichlorophenoxy)propionic acid 3,6-dichloro-2-methoxybenzoic acid... 

ACETIC ACIO (2,4-DICHLOROPHENOXY)- mixed with (2,4,5-TRICHLOROPHENOXY)ACETIC ACIO (2 1) 8015-35-8... 

In spite of their record of producing no detectable harm to humans, the phenoxy herbicides 2,4-dichlorophenoxy acetic acid (2,4-D) and 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) have acquired a less than desirable reputation. This reputation has been the result of their association with low levels of impurities. They have commonly been used as a mixture, which contains trace amounts of highly toxic 2,3,7,8-tetrachlorodibenzo-jj-dioxin, a minor product in the manufacturing of 2,4,5-T. In early production of 2,4,5-T a low level of dioxin was retained. Today s manufacturing process produces 2,4,5-T with no more than 0.1 ppm of the 2,3,7,8 tetrachlorodibenzo-]D-dioxin. This association with toxic dioxin and confusion of the public and the media regarding these issues have led to public distrust in the safety of using phenoxys and to the need to establish clearly the extent of human exposure to these compounds as well as the resulting effects of this exposure. 

Mixtures with other herbicides also are used for weed control. The product Agent Orange, used extensively throughout Vietnam, was about 50% 2,4-D. However, the controversy about the use of Agent Orange was associated with a contaminant (dioxin) in 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) (C8H5Cl303), not with 2,4-D. It should be well understood that 2,4,5-T is different from 2,4-D but similar to 2,4-D as a herbicide component of the defoliant.39... 

FIGURE 11.17 PCA loadings for raw mean-centered augmented data matrix from top to bottom, first to fifth (PCI to PC5) principal components. Compound names and abbreviations are as follows alachlor (ALA), atrazine (ATR), bentazone (BEN), biphenyl (BIF), 3-chlorophenol (3-CP), 4-chlorophenol (4-CP), (2,4-dichlorophenosy)acetic acid (2,4-D), dichloroprop (DCP), dimethoate (DIM), linuron (LIN), h-chloro-z-methyphenoxyacetic acid (MCPA), mecoprop (MEC), 4-chloro-3-methylphenol (MEP), metholachlor (MET), pen-tachlorophenol (PCP), simazine (SIM), (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T), tribu-tylphosphate (TBP), 2,4,6-trichlorophenol (TCP). 

In Chapter 14, we saw that Agent Orange contains (2,4,5-trichlorophenoxy) acetic acid, called 2,4,5-T. This compound is synthesized by the partial reaction of 1,2,4,5-tetrachlorobenzene with sodium hydroxide, followed by reaction with sodium chloroacetate, ClCH2C02Na. 

Preparation of Standards. Standards of isopropyl-, butyl-, isooctyl-, and 2-ethylhexyl 2,4-dichlorophenoxy acetate (2,4-D) and 2-ethylhexyl and isooctyl 2,4,5-trichlorophenoxy acetate (2,4,5-T) were prepared by serial dilution of the pure ester in n-decane to a final concentration of 1—2 nanograms per microliter. 

T [(2,4,5-trichlorophenoxy)acetic acid] because the incubation period of the fungus was 4 to 7 days, and the fungus did not kill the weeds for up to 5 weeks after treatment. Higher rates of inoculum application and humidity (warm, moist, cloudy weather and/or flooding of the rice fields) increased its effectiveness (28-29). 

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