Hydrazine hydrate (1:1) → 2,3-Dihydro-1-benzofuran-6-ol

6-Hydroxycoumaran-3-one (15 g) was suspended in ethanol (75 ml) and hydrazine hydrate (10 ml, 90%) was added and the mixture heated at reflux for 1 hour. The solvent was evaporated and a solution of potassium hydroxide (15 g) in ethylene glycol (100 ml) was added to the residue. The resulting mixture was distilled with stirring until the internal temperature reached 185°-190° C. This temperature was maintained until no more nitrogen was evolved, approximately 1.5 hours. After cooling, the mixture was added to dilute hydrochloric acid containing sufficient acid to make the mixture acidic. This acidified mixture was then extracted with ether, dried and distilled (110°-120° C./0.75 mm) to give 6-hydroxy-2,3-dihydrobenzofuran.

1. temperaturethe mixture heated
2. temperatureat reflux for 1 hour
3. customThe solvent was evaporated
4. additiona solution of potassium hydroxide (15 g) in ethylene glycol (100 ml) was added to the residue
5. distillationThe resulting mixture was distilled
6. customreached 185°-190° C
7. temperatureThis temperature was maintained until no more nitrogen
8. temperatureAfter cooling
9. additionthe mixture was added to dilute hydrochloric acid containing sufficient acid
10. extractionThis acidified mixture was then extracted with ether
11. customdried
12. distillationdistilled (110°-120° C./0.75 mm)

ORD record

ord-d62f4db462e341949f2c61144b814527

Source dataset

uspto-grants-1988_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04780480