24 D dimethyl amine salt 55% SL 600g/l SL 720g/l SL 96% SG 2,4-D herbicides largest pesticide companies

24 D dimethyl amine salt 55% SL 600g/l SL 720g/l SL 96% SG 2,4-D herbicides largest pesticide companies

NOMENCLATURE

2,4-D

Common name 2,4-D (BSI, E-ISO, (m) F-ISO, WSSA); 2,4-PA (JMAF)

IUPAC name (2,4-dichlorophenoxy)  

Chemical Abstracts name (2,4-dichlorophenoxy)  

CAS RN [94-75-7]  EEC no. 202-361-1  Development codes L208 (Marks)  

2,4-D-dimethyl ammonium

IUPAC name dimethylammonium (2,4-dichlorophenoxy)acetate  

CAS RN [2008-39-1]  EEC no. 217-915-8  

PHYSICAL CHEMISTRY

2,4-D

Composition Tech. is ?6% pure.  Mol. wt. 221.0  M.f. C8H6Cl2O3  Form Colourless powder, with a slight ic odour.  M.p. 140.5   V.p. 1.86 ?10-2 mPa (25 , OECD 104)  KOW logP = 2.58-2.83 (pH 1), 0.04-0.33 (pH 5)  Henry 1.32 ?10-5 Pa m3 mol-1 (calc.)  S.g./density 1.508 (20 )  Solubility In water 311 (pH 1), 20 031 (pH 5), 23 180 (pH 7), 34 196 (pH 9) (all in mg/l, 25 ). In  1250,  243,  1.1, toluene 6.7,  5.8 (all in g/kg, 20 ); in octanol 120 g/l (25 ). Insoluble in .  salt: In water 18 g/l (30 ).  Stability 2,4-D is a strong acid, and forms water-soluble salts with alkali metals and amines. Hard water leads to precipitation of the calcium and magnesium salts, but a sequestering agent is included in formulations to prevent this. Photolytic DT50 (simulated sunlight) 7.5 d.  pKa 2.73  

2,4-D-dimethylammonium

Mol. wt. 266.1  M.f. C10H13Cl2NO3  M.p. decomp. c. 120   Solubility In water 3 kg/l (20 ). Soluble in alcohols and acetone. Insoluble in  and diesel oil.  

COMMERCIALISATION

History The potent effects of its salts on plant growth were first described by P. W. Zimmerman & A. E. Hitchcock (Contrib. Boyce Thompson Inst., 1942, 12, 321), and its early history is covered in The Hormone Weedkillers, C. Kirby (1980).  Manufacturers Agrowonderful cellphone 0086 17349771657 ; Dow AgroSciences

APPLICATIONS

Biochemistry Synthetic auxin (acting like indolyl).  Mode of action Selective systemic herbicide. Salts are readily absorbed by the roots, whilst esters are readily absorbed by the foliage. Translocation occurs, with accumulation principally at the meristematic regions of shoots and roots. Acts as a growth inhibitor.  Uses Post-emergence control of annual and perennial broad-leaved weeds in cereals, maize, sorghum, grassland, established turf, grass seed crops, orchards (pome fruit and stone fruit), cranberries, asparagus, sugar cane, rice, forestry, and on non-crop land (including areas adjacent to water), at 0.28-2.3 kg/ha. Control of broad-leaved aquatic weeds. The isopropyl ester can also be used as a plant growth regulator to prevent premature fruit fall in citrus fruit. Phytotoxicity Phytotoxic to most broad-leaved crops, especially cotton, vines, tomatoes, ornamentals, fruit trees, oilseed rape and beet.  Formulation types EC; GR; SP; SL.

ANALYSIS

Product analysis of 2,4-D, salts, esters and mixed combination products by acid-base titration, by glc (CIPAC Handbook, 1985, 1C, 2060, 2257; 1994, F, 292-319; Herbicides 1977, pp. 6-21), by rplc (AOAC Methods, 17th Ed., 971.07, 976.03, 978.05, 984.07; CIPAC Handbook, 1985, 1C, 2060; 1988, D, 51), by hplc (ibid., 1983, 1757), or by i.r. spectrometry (ibid., 1998, H, 131). Free  impurity determined by glc (CIPAC Handbook, 1994, F, 197), hplc (ibid., 1994, F, 362) or electrochemically (ibid., 1994, F, 368). Residues determined by glc of derivatives (Pestic. Anal. Man., 1979, I, 201-D; Anal. Methods Pestic. Plant Growth Regul., 1972, 6, 630) or by hplc (M. Meier et al.,Fresenius Z. Anal. Chem.,1989, 334, 235). In drinking water, by conversion to methyl ester with , then glc with ECD (AOAC Methods, 17th Ed., 992.32).  

MAMMALIAN TOXICOLOGY

Reviews FAO/WHO 77, 79, 80, 82, 92 (see part 2 of the Bibliography). Toxicity and hazards to man, domestic animals and wildlife have been reviewed (J. M. Way, Residue Rev., 1969, 26, 37).  IARC ref. 15, 41; Suppl. 7  class chlorophenoxy herbicides classified as 2B, based on epidemiology of production. More recent evidence (M. Kogevinas et al., Am. J. Epidemiol., 145(12), 1061 (1997)) relates this to dioxin contamination of early production. Not relevant to current processes.  

2,4-D-dimethylammonium

Oral Acute oral LD 50 for rats 949 mg/kg.  Skin and eye LD50 for rats >2000 mg/kg; not a skin irritant (rabbits); severe irritant to eyes (rabbits).  Inhalation LC50 (4 h) for rats >3.5 mg/l air.  

ECOTOXICOLOGY

2,4-D

Birds Acute oral LD50 for wild ducks >1000, Japanese quail 668, pigeons 668, pheasants 472 mg/kg. LC50 (96 h) for mallard ducks >5620 mg/l.  Fish Some formulations (e.g. esters) are toxic to fish, whilst others are not. LC50 (96 h) for rainbow trout >100 mg/l.  Daphnia LC50 (21 d) 235 mg/l.  Algae EC50 (5 d) for Selenastrum capricornutum 33.2 mg/l.  Other aquatic spp. EC50 (14 d) for Lemna gibba 0.58 mg/l.  Bees Not toxic to bees; LD50 (oral) 104.5 mg/bee.  Worms LC50 (7 d) 860 mg/kg; NOEC (14 d) 100 g/kg.  Other beneficial spp. Harmless to Trichogramma cacoeciae, Poecilus cupreus, Aleochara bilineata.  

2,4-D-dimethylammonium

Birds Acute oral LD 50 for bobwhite quail 500 mg/kg. Oral LC50 for bobwhite quail >5620 ppm.  Fish LC50 (96 h) for rainbow trout 100 mg/l.  Algae EC50 for Selenastrum capricornutum 51.2 mg/l.  Bees LD50 (contact) >100 /bee; (oral) c. 94 /bee.