申请人:CIBA-GEIGY AG
公开号:EP0710649A1
公开(公告)日:1996-05-08
2,3-Difluoro-5-halopyridines of the formula I
wherein X is Cl or Br are prepared by a process which comprises reacting a starting 2,3,5-trihalopyridine of the formula II
wherein each X is individually Br or Cl and Y is F, Cl or Br with an effective amount of potassium fluoride in the presence of a mixture of sulfolane and a tetralkylurea and/or a dialkyl-alkyleneurea as diluent, at an effective temperature up to the boiling point of the diluent, optionally in the presence of a phase-transfer catalyst such as a crown ether or polyglycol ether. The compounds are useful as intermediates to prepare herbicides.
式 I 的 2,3-二氟-5-吡啶卤化物
其中 X 为 Cl 或 Br 的 2,3,5-三卤吡啶的制备工艺包括使式 II 的 2,3,5-三卤吡啶起始物发生反应
其中每个 X 单独为 Br 或 Cl,Y 为 F、Cl 或 Br,与有效量的氟化钾在磺烷和四烷基脲和/或二烷基亚烷基脲的混合物作为稀释剂的存在下,在有效温度至稀释剂沸点的条件下,任选在冠醚或聚乙二醇醚等相转移催化剂的存在下进行反应。这些化合物可用作制备除草剂的中间体。