Hydrochloric Acid → Thiophen-3-amine oxalate

Temperature

115 °C

Methyl 3-aminothiophene-2-carboxylate (1.52 g, 9.68 mmol) is dissolved in 2M NaOH (10 mL, 20 mmol) and refluxed in a 115° C. oil bath for 30 min. The mixture is cooled to rt, placed in an ice bath, and carefully acidified with concentrated HCl. The slurry is filtered and rinsed with water (25 mL). The cake is then dissolved in acetone (50 mL), dried over MgSO4, filtered, and concentrated to a thick paste. The crude material is dissolved in 1-propanol (25 mL), and oxalic acid (0.90 g, 10.0 mmol) is added portionwise. The mixture is heated at 38° C. for forty-five min, cooled to rt, and diluted with ether. The precipitate is isolated via filtration, and washed with ether, affording 3-amino-thiophene oxalate (C135) as a fluffy white solid (70% yield). HRMS (FAB) calculated for C4H5NS+H: 100.0221, found 100.0229 (M+H)+.

1. temperatureThe mixture is cooled to rt
2. customplaced in an ice bath
3. filtrationThe slurry is filtered
4. washrinsed with water (25 mL)
5. dissolutionThe cake is then dissolved in acetone (50 mL)
6. dry with materialdried over MgSO4
7. filtrationfiltered
8. concentrationconcentrated to a thick paste
9. dissolutionThe crude material is dissolved in 1-propanol (25 mL)
10. temperatureThe mixture is heated at 38° C. for forty-five min
11. temperaturecooled to rt
12. customThe precipitate is isolated via filtration
13. washwashed with ether

ORD record

ord-f7180bc9437f408ca0a9899fc0081c4e

Source dataset

uspto-grants-2006_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07067515B2