Ethanol → Ethyl pyrazinecarboxylate

To a solution of pyrazine-2-carboxylic acid (100 g) in ethanol (EtOH, 1000 ml) was added conc. sulfuric acid (45 ml) at room temperature. After refluxing for 8 hours, the reaction mixture was concentrated in vacuo. The residue was dissolved in ethyl acetate (AcOEt, 1500 ml) and water (H2O, 1000 ml), and sodium hydrogencarbonate (NaHCO3) was added to adjust the pH of the mixture to 8. The aqueous layer was extracted with AcOEt (1000 ml), and the combined organic layer was washed with brine and dried over magnesium sulfate (MgSO4). The solution was concentrated in vacuo, and the residue was crystallized from hexane (1000 ml) to give 111.2 g of ethyl pyrazine-2-carboxylate,

1. temperatureAfter refluxing for 8 hours
2. concentrationthe reaction mixture was concentrated in vacuo
3. dissolutionThe residue was dissolved in ethyl acetate (AcOEt, 1500 ml)
4. additionwater (H2O, 1000 ml), and sodium hydrogencarbonate (NaHCO3) was added
5. extractionThe aqueous layer was extracted with AcOEt (1000 ml)
6. washthe combined organic layer was washed with brine
7. dry with materialdried over magnesium sulfate (MgSO4)
8. concentrationThe solution was concentrated in vacuo
9. customthe residue was crystallized from hexane (1000 ml)

ORD record

ord-40376bd9c0a84a938135e2e7365f619c

Source dataset

uspto-grants-2001_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06333324B1