Dicamba

Common name  dicamba

IUPAC name 3,6-dichloro-o-anisic acid 

Chemical Abstracts name 3,6-dichloro-2-methoxybenzoic acid 

CAS RN [1918-00-9]; 5-hydroxy derivative [7600-50-2]

Composition Tech. grade purity is 85% w/w, remainder being mainly 3,5-dichloro-o-anisic acid.  Mol. wt. 221.0  M.f. C8H6Cl2O3  Form Colourless crystals; (tech. is a buff crystalline solid).  M.p. 114-116 篊  B.p. >200 篊  V.p. 1.67 mPa (25 篊, calc.)  KOW logP = -0.55 (pH 5.0), -1.88 (pH 6.8), -1.9 (pH 8.9) (OECD 105)  Henry 6.1 ´ 10-5 Pa m3 mol-1  S.g./density 1.488 (25 篊)  Solubility In water 6.1 g/l (25 篊). In ethanol 922, cyclohexanone 916, acetone 810, dichloromethane 260, dioxane 1180, toluene 130, xylene 78 (all in g/l, 25 篊).  Stability Resistant to oxidation and hydrolysis under normal conditions. Stable in acids and alkalis. Decomposes at c. 200 篊.

Mode of action

Selective systemic herbicide, absorbed by the leaves and roots, with ready translocation throughout the plant via both the symplastic and apoplastic systems. Acts as an auxin-like growth regulator.