2-Amino-3,5-dibromopyrazine

• 2-amino-5-bromopyrazin-3-thiol
• 2-amino-3,5-bis(p-methoxyphenyl)-1,4-pyrazine
• 3,7-dihydroimidazo[1,2a]pyrazine-3-ones

5049-61-6

24241-18-7

The general procedure for the synthesis of 2-amino-3,5-dibromopyrazine from 2-aminopyrazine was as follows: 2-aminopyrazine (9.5 g, 100 mmol) was added to a reaction flask containing glacial acetic acid (70 mL) and heated on a steam bath until completely dissolved. Subsequently, sodium acetate trihydrate (33 g, 243 mmol) was added and constant stirring was maintained. The reaction mixture was cooled in an ice-salt bath at -5°C and bromine (16 mL) was added slowly and dropwise over a period of 4 hours (note: rapid addition of bromine may result in uncontrolled reaction and pose a safety hazard). After the dropwise addition was completed, stirring was continued in the ice bath for 2 hours, then moved to room temperature and stirred for 24 hours. Upon completion of the reaction, the mixture was poured into ice (50 g) and neutralized by adjusting to pH 8 with concentrated ammonia. The crude product was collected by filtration and recrystallized from methanol (with the addition of Norit activated charcoal) to give the final 2-amino-3,5-dibromopyrazine in colorless needles (16.8 g, 66% yield) with a melting point of 113-114 °C (literature value: 114-115 °C).