3,6-di:chloro-salicylic acid prodn. - from potassium 2,5-di:chloro-phenoxide and carbon di:oxide in presence of potassium carbonate

摘要

Prodn. of 3,6-dichlorosalicylic acid (I) is carried out by carboxylating K 2,5-dichlorophenoxide (II) in xylene with CO2 under pressure, with the improvement that finely divided anhydrous K2CO3 is added to the reaction mixt. The K2CO3 is pref. added in an amt. of 1-2 (esp. 1.2-1.8) moles per mole of (II). (I) is an intermediate for the herbicide dicamba (2-methoxy-3,6-dichlorobenzoic acid). Addn. of K2CO3 approx. doubles the yield, e.g. to 60% (cf. US 301 3054).