Water → 3-Bromo-5-chloropyridin-2-amine

Participants

Reaction Steps

A solution of 257 g (1.61 mol) of bromine in 380 ml of acetic acid was added dropwise over a period of one hour to a solution of 187 g (1.45 mol) of 2-amino-5-chloropyridine in 1.5 l of acetic acid. The reaction mixture was refluxed for 3 h and then allowed to cool to ambient temperature. 1.9 l of demineralized water were added and the mixture was concentrated in vacuo. The residue was partitioned between 4 l of ethyl acetate and 1.8 l of water. The mixture was basified with 3 l of a 10% by weight aqueous sodium hydroxide solution. The organic layer was separated and washed with brine (2×1.5 l), dried over magnesium sulfate, filtered and concentrated in vacuo. The residue was filtered, washed with hexane (2×100 ml) and dried in vacuo to give 192 g of 2-amino-3-bromo-5-chloropyridine. The mother liquor was concentrated in vacuo, filtered, washed with hexane and dried to give further 75 g of the same product.

Provenance & Evidence