申请人:Ciba-Geigy Corporation
公开号:US04258194A1
公开(公告)日:1981-03-24
A novel process for producing 2,3,5-trichloropyridine is described. In this process, 2,3,4,5-tetrachloropyridine is reacted, in an alkanephosphonic acid dialkyl ester (dialkyl alkane phosphonate) having 1 to 4 carbon atoms in each of the alkyl groups or in a phosphoric acid trialkyl ester (trialkyl phosphate) having 1 to 4 carbon atoms in each of the alkyl groups as the solvent, at 60.degree. to 120.degree. C., in the presence of 1.4 to 2.8 mols, per mol of 2,3,4,5-tetrachloropyridine, of an ammonium salt of an inorganic or organic acid, with 1.2 to 1.6 gram atoms of zinc per mol of 2,3,4,5-tetrachloropyridine, the 2,3,4,5-tetrachloropyridine being selectively dechlorinated in the 4-position. 2,3,5-Trichloropyridine is a valuable intermediate for producing herbicidally effective .alpha.-[4-(3',5'-dichloropyrid-2-yloxy)-phenoxy-]-alkanecarboxylic acids and derivatives thereof. There are also described novel ammonium salts of methanephosphonic acid monomethyl ester, in the presence of which salts the selective dechlorination of 2,3,4,5-tetrachloropyridine in the 4-position is advantageously performed.
描述了一种生产2,3,5-三氯吡啶的新工艺。在这个工艺中,以1至4个碳原子的烷基组成的烷基膦酸二烷基酯(二烷基烷基膦酸酯)或者以1至4个碳原子的烷基组成的磷酸三烷基酯(三烷基磷酸酯)为溶剂,在60至120摄氏度下,以每摩尔2,3,4,5-四氯吡啶1.4至2.8摩尔的无机或有机酸铵盐存在下,每摩尔2,3,4,5-四氯吡啶1.2至1.6克原子的锌存在下,选择性去氯化四位的2,3,4,5-四氯吡啶。2,3,5-三氯吡啶是生产具有除草效果的α-[4-(3',5'-二氯吡啶-2-氧基)-苯氧基]-烷基羧酸及其衍生物的有价值中间体。还描述了新型的甲烷膦酸单甲酯铵盐,在这些盐的存在下,有利地进行了2,3,4,5-四氯吡啶在四位的选择性去氯化。