2,4-D除草剂

Mol. wt. 221.0 M.f. C8H6Cl2O3 Form Colourless powder, with a slight phenolic 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 0.7-0.8 Solubility In water 311 (pH 1), 20 031 (pH 5), 23 180 (pH 7), 34 196 (pH 9) (all in mg/l, 25 ). In ethanol 1250, diethyl ether 243, heptane 1.1, toluene 6.7, xylene 5.8 (all in g/kg, 20 ); in octanol 120 g/l (25 ). Insoluble in petroleum oils. Mono-n-butylamine 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