Hydrochloric Acid → 5-(methylthio)-1H-indole-2,3-dione

Temperature

90 °C

A mixture of 4-(methylthio)aniline (13.92 g, 100 mmol) and diethyl ethanedioate (17.42 g, 100 mmol) in acetic acid (50 mL) was stirred at 90° C. for 8 h. The mixture was cooled to room temperature and allowed to stand overnight, at which time the product had crystallized. The crystals were collected by filtration and washed with minimal acetic acid. The crystals were dissolved in 5% sodium hydroxide (150 mL), and the solution was heated to 90° C. Air was bubbled through the solution continuously, forming a yellow solution. After 8 hours, the solution was cooled and acidified with concentrated HCl. The precipitate was collected by filtration and was washed with water and dried to afford 5-(methylthio)-1H-indole-2,3-dione (1.9 g, 10% yield). MS (m/z) 194.0 (M+H+).

1. temperatureThe mixture was cooled to room temperature
2. waitto stand overnight, at which time
3. customthe product had crystallized
4. filtrationThe crystals were collected by filtration
5. washwashed with minimal acetic acid
6. dissolutionThe crystals were dissolved in 5% sodium hydroxide (150 mL)
7. temperaturethe solution was heated to 90° C
8. customAir was bubbled through the solution continuously
9. customforming a yellow solution
10. waitAfter 8 hours
11. temperaturethe solution was cooled
12. filtrationThe precipitate was collected by filtration
13. washwas washed with water
14. customdried

ORD record

ord-a1eede773f034c3dad6ba7512fe942b0

Source dataset

uspto-grants-2014_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08658636B2