Hydrogen Bromide → 2-Bromo-5-methyl-7-phenyl-1,2,4-triazolo[1,5-a]pyrimidine

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Reaction Steps

To 2.0 g (8.9 mmol) of 5-methyl-7-phenyl-1,2,4-triazolo[1,5-a]pyrimidin-2-amine stirring in a mixture of 20 ml of 48% hydrobromic acid and 10 ml of glacial acetic acid, 2.0 g (29.0 mmol) of sodium nitrite was slowly added portionwise with good stirring at ambient temperature. The thick suspension was stirred at about 60° C. for 15 minutes followed by stirring another 10 minutes without heat. Ethyl acetate (150 ml) and excess water were added. The ethyl acetate layer was separated whereby a certain amount of insoluble material present was ignored and the extract washed with water (2X), saturated sodium bicarbonate, brine, dried over magnesium sulfate, and evaporated in vacuo to give a solid residue. Silica gel column chromatography (methylene chloride followed by 10:1 methylene chloride/ethyl acetate) afforded the title compound, 15 m.p. 178°-180° C.

Provenance & Evidence