Picloram

4-Amino-3,5,6-trichloro-2-pyridinecarboxylic acid 4-amino-3,5,6-trichloropicolinic acid, Tordon. 

Colorless powder with chlorine-like odor decomposes before melting at 215°CA3 

Wear gloves and eye protection. The powder can be swept up and discarded as for waste disposal. For spills of solutions of Picloram, cover with a 1 1 1 mixture of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand. Scoop the mixture into a container and add to a pail of water. Acidify the liquid by the careful addition of 3 M sulfuric acid (8 mL of concentrated sulfuric acid added to 42 mL of water) to pH 1. Estimate the weight of Picloram in the spill and add 5 g of potassium permanganate for each 0.3 g of Picloram. Stir thoroughly and allow it to stand at room temperature overnight. Reduce the excess permanganate by the addition of sodium bisulfite until no 

Armour, M.A., Decontamination of spills and residues of pesticides and protective clothing worn during their handling, Proceedings of the Pacific Basin Conference on Hazardous Waste Research, Kulala Lumpur, Malaysia, 1996, p. 44. 

IUPAC name 4-amino-3,5,6-trichloropyridime-2-carboxylic acid Molecular formula C6H3 CL3N2O2 

Uses Picloram belongs to the pyridine family of compounds. It is a systemic herbicide used for the control of woody plants and a range of broadleaf weeds. Most grasses are resistant to picloram. It is classified by the USEPA as RUP because of its mobility in water, combined with extreme sensitivity to many important crop plants.2,12,13,37 

IUPAC name 2,4-dichlorophenoxy acetic acid Molecular formula CgHeC CE Toxicity class USEPA II WHO II 

Uses 2,4-D is a colorless powder with a mild phenylic odor. There are many derivatives of 2,4-D, including esters, amines, and salts. As a systemic herbicide, it is used to control many types of broadleaf weeds. It is used in cultivated agriculture, in pasture and rangeland applications, forest management, home, garden, and to control aquatic vegetation. It may be found in emulsion form, in aqueous solutions (salts), and as a dry compound. 

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 

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Other auxin-like herbicides (2,48) include the chlorobenzoic acids, eg, dicamba and chloramben, and miscellaneous compounds such as picloram, a substituted picolinic acid, and naptalam (see Table 1). Naptalam is not halogenated and is reported to function as an antiauxin, competitively blocking lAA action (199). TIBA is an antiauxin used in receptor site and other plant growth studies at the molecular level (201). Diclofop-methyl and diclofop are also potent, rapid inhibitors of auxin-stimulated response in monocots (93,94). Diclofop is reported to act as a proton ionophore, dissipating cell membrane potential and perturbing membrane functions. 

A study investigating the breakdown of clopytaUd [1702-17-6] reported half-Hves on different soils of approximately 2—7 weeks in a laboratory incubation (400) it was indicated that carryover was likely to occur in field soil. Picloram degrades and does not accumulate in field soil although low residue levels do persist for several years (401). The half-life for triclopyr [55335-06-3] is reported to be two weeks in two Canadian soils (402), and it has been shown to be rapidly degraded by aqueous photolysis (403). 

The primary use of a-picoline (2) is as a precursor of 2-vinylpyridine (23). It is also used in a variety of agrochemicals and pharmaceuticals, such as nitrapyrin [1929-82-4] (60) to prevent loss of ammonia from fertilizers picloram [1918-02-1] (61), a herbicide and amproHum [121 -25-5] (62), a coccidiostat. 

TOMES PLUS hiforniation System., 307 Toniita Pharmaceutical Co. Ltd., 190 Tomiyama Pure Chemical Industries Ltd., 190 Topnote Aromatics Ltd., 176 TOR Minerals International, 250 Toray Fine Chemicals Co. Ltd., 190 Toray Industries hic., 190 TORDON , picloram, 130 Tosco Corporation, 251 Tosoh Corporation, 190... 

Martin, S.C. Morton, H.L. (1980). Responses of false mesquite, native grasses and forbs and Lehmann lovegrass after spraying with picloram. Journal of Range Management, 33, 104-6. 

Phosphoius pentachlonde Phosphorus penrasulphide Phosphorus trichlodde PKthalk anhydride m-Phthalodinitfile Picloram" ... 

The recovery of vegetation in a tropical rainforest in Puerto Rico — after plants were deliberately subjected to lethal doses of gamma radiation — closely resembled secondary succession after other types of disturbances, such as mechanical stripping and treatment with the Picloram herbicide (Jordan 1969). 

Krzyszowska AJ, Vance GF. Solid-phase extraction of dicamba and picloram from water and soil samples for HPLC analysis. J. Agric. Food Chem. 1994 42 1693-1696. 

Abbott et al. [163] described a pyrolysis unit for the determination of Picloram and other herbicides in soil. The determination is effected by electron capture-gas chromatography following thermal decarboxylation of the herbicide. Hall et al. [164] reported further on this method. The decarboxylation products are analysed on a column (5mm i.d.) the first 15cm of which is packed with Vycor chips (2-4mm), the next 1.05m with 3% of SE-30 on Chromosorb W (60-80 mesh) and then 0.6m with 10% of DC-200 on Gas Chrom Q (60-80 mesh). The pyrolysis tube, which is packed with Vycor chips, is maintained at 385°C. The column is operated at 165°C with nitrogen as carrier gas (110ml min-1). The method when applied to ethyl ether extracts of soil gives recoveries of 90 5%. Dennis et al. [165] have reported on the accumulation and persistence of Picloram in bottom deposits. 

Recoveries in excess of 80% were achieved for 2,4-D, Dicamba, 3,6-dichloropicolinic acid, Dichloroprop, Picloram, 2,4,5-T Fenoprop, 2,3,6-TBA, Bromoxynil and Ioxynil (Table 9.22). 

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. 

Many methods have been reported for the extraction of these compounds from soil. Khan [225] used acidified acetone followed by methylation with diazomethane for the simultaneous determination of 2,4-D, Dicamba and Mecoprop residues, as did Bache and Lisk [226] for Ioxynil. Abbott et al. [227] developed a method for MCPA, MCPB, 2,4-D Dichloroprop and 2,4,5-T in which dilute sulphuric acid and diethyl ether were used for extraction. Byast et al. [101] have shown that diethyl ether-chloroform-acetic acid is a suitable extractant for 2,4,5-T, 2,4-D, Dichloroprop and Dicamba [101] and saturated calcium hydroxide solution is efficient for Picloram [228] and 3,6-dichloropicolinic acid [229]. 

Groundwater contamination by agrochemicals from non-point sources has been well documented in a number of countries [26-28, 30-32], The pesticides that have been detected in regional council groundwater surveys include 2,4-D, Amitrole, Picloram, Simazine and Atrazine [20]. 

The rate at which pollutants sorb to sediments has frequently been assumed to occur rapidly and consequently equilibration studies have often been conducted by mixing sample for 24 hours. Karickhoff (I, 66) has reported that sorption may require up to two months to reach an apparent equilibrium. Similarly, desorption has also been observed to require on the order of months to reach completion (67, 68). McCall and Agin (67) observed that the desorption rate of picloram was inversely related to the contact time. 

With the exception of picloram and phenols (Fig. 10, Table 3), acidic pesticides are considered nonvolatile from aqueous and soil systems [153]. Some ester formulations of these compounds also behave as herbicides. They do not ionize in solution and are less water-soluble than the acid or salt forms. They are eventually hydrolyzed to acid anions in aqueous and soil systems, but in the ester form are non-ionic and relatively volatile. 

Van der Waals forces were considered to be involved in the physical adsorption of Carbaryl, Parathion, Alachlor, Picloram, and 2,4-D by SPHs [17,25,152, 160-162]. 

Picloram [19180-02-1] Daphnla magna EC50 (48-h) 1.88 Mayer and Ellersieck, 1986... 

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