Hydrochloric Acid → 3-Methoxythiophene-2-carboxylic acid

To a solution of methyl 3-methoxythiophene carboxylate (2.0 g, 11.6 mmol) in 20 mL of THF at room temperature was added dropwise a 1.0 M sodium hydroxide aqueous solution (17.0 mL, 17.0 mmol). After addition, the mixture was heated to 75° C. (oil bath temperature) and continued for 18 h. The mixture was cooled to room temperature, treated with a 1.0 M hydrochloride aqueous solution until pH approximately being 2. The acidified mixture was extracted with 100 mL of CH2Cl2—CH3CN (1:1, v/v), 50 mL of CH2Cl2, and 50 mL of CH3CN. The combined organic extracts were washed with brine (30 mL), dried over Na2SO4, and concentrated under reduced pressure to a solid, which was further dried on high vacuum, yielding 1.84 g (100%) of 3-methoxythiophene carboxylic acid (MH+=159.0).

1. additionAfter addition
2. temperatureThe mixture was cooled to room temperature
3. extractionThe acidified mixture was extracted with 100 mL of CH2Cl2—CH3CN (1:1
4. washThe combined organic extracts were washed with brine (30 mL)
5. dry with materialdried over Na2SO4
6. concentrationconcentrated under reduced pressure to a solid, which
7. customwas further dried on high vacuum

ORD-Eintrag

ord-7d13398bb5a048d594b04e21531bd4b8

Quelldatensatz

uspto-grants-2005_06

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06903131B2