2,4-D

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

IUPAC name (2,4-dichlorophenoxy)acetic acid 

Chemical Abstracts name (2,4-dichlorophenoxy)acetic acid 

CAS RN [94-75-7]

Composition Tech. is ³96% pure. 

Mol. wt. 221.0 

M.f. C8H6Cl2O3 

Form Colourless powder, with a slight phenolic odour. 

M.p. 140.5 篊 

V.p. 1.86 ´ 10-2 mPa (25 癈, 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 癈) 

Solubility In water 311 (pH 1), 20 031 (pH 5), 23 180 (pH 7), 34 196 (pH 9) (all in mg/l, 25 癈). In ethanol 1250, diethyl ether 243, heptane 1.1, toluene 6.7, xylene 5.8 (all in g/kg, 20 篊); in octanol 120 g/l (25 癈). Insoluble in petroleum oils. Mono-n-butylamine salt: In water 18 g/l (30 篊).

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