2,3-Dihydro-1,4-benzodioxin-5-carboxylic acid → 2,3-Dihydro-1,4-benzodioxin-5-amine--hydrogen chloride (1/1)

Temperature

120 °C

1,4-Benzodioxan-5-carboxylic acid (120 g) was added in portions at 40° C. to a stirred mixture of hydroxylamine hydrochloride (52 g) and polyphosphoric acid (380 g), then the mixture was heated to an internal temperature of 120° C. The source of heat was removed, and the mixture was stirred vigorously until frothing subsided, then it was stirred at 165° C. for 90 minutes, cooled to 80° C., added to an excess of ice-water, and basified by the addition of 5M aqueous sodium hydroxide solution. The product was extracted into ethyl acetate (6×500 ml), the extracts were dried (MgSO4), and the solvent removed in vacuo. The residue was dissolved in ethyl acetate (800 ml), and the cloudy solution was filtered then saturated with hydrogen chloride. The resulting solid was collected by filtration, washed with ethyl acetate, and dried in vacuo at ambient temperature to give 1,4-benzodioxan-5-amine monohydrochloride as a buff solid (65.9 g).

1. temperatureThe source of heat
2. customwas removed
3. stirringit was stirred at 165° C. for 90 minutes
4. temperaturecooled to 80° C.
5. additionadded to an excess of ice-water
6. additionbasified by the addition of 5M aqueous sodium hydroxide solution
7. extractionThe product was extracted into ethyl acetate (6×500 ml)
8. dry with materialthe extracts were dried (MgSO4)
9. customthe solvent removed in vacuo
10. dissolutionThe residue was dissolved in ethyl acetate (800 ml)
11. filtrationthe cloudy solution was filtered
12. filtrationThe resulting solid was collected by filtration
13. washwashed with ethyl acetate
14. customdried in vacuo at ambient temperature

ORD record

ord-eecc939721214b8ca9e85445dcbd2635

Source dataset

uspto-grants-2000_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06114334