Hydrogen Bromide → 6-Bromo-3-chloropicolinic acid

Temperature

110 °C

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.

1. additionFor workup, the reaction mixture is poured onto ice-water
2. filtrationThe contents are filtered
3. washthe residue is washed with water
4. customThe residue obtained
5. customThe filtrate is freed of the solvents on a rotary evaporator
6. stirringthe residue is stirred with water
7. filtrationThe mixture is filtered
8. customthe residue obtained

ORD record

ord-ec8e9a70405f4770bcbefde8209b1bb3

Source dataset

uspto-grants-2015_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08962529B2