White to light brown solid, flakes, crystal powder or liquid. Same as 2,4-D except for replacement of one chlorine atom by a met

Composition Tech. grade is 85-99% pure.  Mol. wt. 200.6  M.f. C9H9ClO3  Form Colourless crystals; odourless, or with a mild phenolic odour.  M.p. 119-120.5 ; (tech. 115-117 )  V.p. 2.3 ?10-2 mPa (20 ); 4 ?10-1 mPa (32 )  KOW logP = 2.75 (pH 1), 0.59 (pH 5), -0.71 (pH 7) (25 )  Henry 5.5 ?10-5 Pa m3 mol-1 (calc.)  S.g./density 1.41 (23.5 )  Solubility In water 395 (pH 1), 26.2 (pH 5), 273.9 (pH 7), 320.1 (pH 9) (all in mg/l, 25 ). In diethyl ether 770, toluene 26.5, xylene 49, heptane 5, methanol 775.6, dichloromethane 69.2, n-octanol 218.3 (all in g/l, 25 ).  Stability The acid is chemically very stable. Forms water-soluble alkali-metal and amine salts, although precipitation of calcium or magnesium salts may occur in hard water. Photochemical DT50 (artificial sunlight) 25.4 d (25 ).  pKa 3.07 

MCPA