反应详情

The reaction was carried out, under nitrogen, in a 1 L×4 neck flask equipped with a mechanical stirrer, water condenser (with gas inlet), and a thermocouple. The reactor was charged with 5-methylpyrazinecarboxylic acid (100 g), and acidic cation exchange resin (20 g), and methanol (300 g). The mixture was stirred at reflux for about 20 h. After the reaction was complete (analyze with GC or GC/MS), the resin was removed by pressure filtration. The resin was rinsed with methanol and about 75% of the solvent was removed under reduced pressure. The resulting suspension was allowed to stand at room temperature overnight, and then in an ice-bath for 3 h. The solid was collected by filtration and washed with ice-cold methanol (2×80 g). Drying under vacuum at room temperature (25 inches of Hg) yielded 102.4 g (93%) of 5-methyl-2-pyrazinecarboxylic acid, methyl ester that was suitable for further use.

1. customequipped with a mechanical stirrer, water condenser (with gas inlet)
2. temperatureat reflux for about 20 h
3. customthe resin was removed by pressure filtration
4. washThe resin was rinsed with methanol and about 75% of the solvent
5. customwas removed under reduced pressure
6. waitin an ice-bath for 3 h
7. filtrationThe solid was collected by filtration
8. washwashed with ice-cold methanol (2×80 g)
9. customDrying under vacuum at room temperature (25 inches of Hg)