Hydrochloric Acid → 3,4-Dihydroxybenzonitrile

Temperature

180 °C

To a 4-necked 1 L round bottom flask equipped with a mechanical stirrer and a condenser, 3-methoxy-4-hydroxybenzonitrile 2a (70.7 g, 0.47 mole), lithium bromide (81.3 g, 0.94 mole), and N,N′-dimethylformamide (220 mL) were added successively at 25° C., followed by heating in an oil bath at 180° C. for 10 hours. The reaction mixture was allowed to cool to 85° C. Water (285 mL) was then added, and upon cooling to 25° C., and treatment with concentrated hydrochloric acid proceed. The resulting mixture was extracted with ethyl acetate (300 mL×2). The extract was concentrated under reduced pressure to give a pale brown solid. Water (430 mL) was added and the mixture was then heated till the mixture became homogeneous. After the reaction mixture was cooled down to approximately 40° C., 3,4-Dihydroxybenzonitrile was precipitated out and the reaction mixture was further cooled to 10° C. so as to ensure complete precipitation. The resulting solid was isolated by filtration and dried under reduced pressure. 3,4-Dihydroxybenzonitrile (42.5 g) was obtained as a white solid with a yield of 67% and a purity of greater than 99% as indicated by HPLC analysis.

1. customTo a 4-necked 1 L round bottom flask equipped with a mechanical stirrer and a condenser
2. temperatureto cool to 85° C
3. temperatureupon cooling to 25° C.
4. extractionThe resulting mixture was extracted with ethyl acetate (300 mL×2)
5. concentrationThe extract was concentrated under reduced pressure
6. customto give a pale brown solid
7. temperaturethe mixture was then heated till the mixture
8. temperatureAfter the reaction mixture was cooled down to approximately 40° C.
9. custom3,4-Dihydroxybenzonitrile was precipitated out
10. temperaturethe reaction mixture was further cooled to 10° C. so as
11. customprecipitation
12. customThe resulting solid was isolated by filtration
13. customdried under reduced pressure

ORD record

ord-0ec6ebd70e564627933198d3dad64aea

Source dataset

uspto-grants-2004_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06790977B2