Hydrogen Bromide → 6-Bromo-3-chloropicolinic acid
反応式
[Cl:1][C:2]1[C:3]([C:9]([OH:11])=[O:10])=[N:4][C:5](Cl)=[CH:6][CH:7]=1.[BrH:12]>C(O)(=O)C>[Br:12][C:5]1[N:4]=[C:3]([C:9]([OH:11])=[O:10])[C:2]([Cl:1])=[CH:7][CH:6]=1参加物
4
反応条件
- 温度
- 110 °C
実験手順
20.0 g (104.2 mmol) of 3,6-dichloropyridine-2-carboxylic acid are admixed with 50 ml of acetic acid. Then 5 ml (33% by weight; 28.96 mmol) of a solution of hydrogen bromide in acetic acid are added. The mixture is heated to 110° C., and a further 22 ml (33% by weight; 127.4 mmol) of a solution of hydrogen bromide in acetic acid are added dropwise at this temperature. The reaction mixture is stirred at 110° C. until monitoring of the reaction by HPLC indicates virtually complete conversion. To accelerate the conversion, a further 40 ml in total (33% by weight; 231.7 mmol) of a solution of hydrogen bromide in acetic acid are added dropwise on three occasions during the reaction. For workup, the reaction mixture is poured onto ice-water. The contents are filtered and the residue is washed with water. The residue obtained is 20.5 g of the product with a purity of approx. 95% by weight. The filtrate is freed of the solvents on a rotary evaporator and the residue is stirred with water. The mixture is filtered; the residue obtained is 2.78 g of the product with a purity of approx. 89% by weight.