Bromine → 1-(4-Amino-3-bromo-5-methylphenyl)-2,4-dimethylimidazole

Participants

Reaction Steps

A solution of bromine (5.6 cm3) in glacial acetic acid (50 cm3) was added dropwise over 0.5 hours to a stirred solution of 1-(4-amino-3-methylphenyl)-2,4-dimethylimidazole (20.3 g) and sodium acetate (9.02 g) in glacial acetic acid (200 cm3). After a further 0.5 hours, volatile material was removed in vacuo, and the residue was partitioned between chloroform (200 cm3) and 10% aqueous sodium hydroxide solution (to pH 10). The aqueous phase was further extracted with chloroform (2×100 cm3) and the combined and dried (MgSO4) organic extracts were evaporated in vacuo to afford a solid which was chromatographed on silica (Merck "MK 60.9385" [Trade Mark]) eluting with dichloromethane:methanol, 19:1. Combination and evaporation of the appropriate fractions gave an oil which was triturated with ether to afford the title compound, m.p. 176°-180.5°. The mother liquors were evaporated and the residue was rechromatographed on silica, as before, to give a further crop of material (total yield 17.3 g).

Provenance & Evidence