Acetic Anhydride → 5-cyanofuran-2-carboxylic Acid

Temperature

85 °C

A 250-mL, three-neck, round-bottom flask equipped with a mechanical stirrer, a heating mantle, and a condenser was charged with 5-formyl-2-furancarboxylic acid (9.18 g, 65.6 mmol) and pyridine (60 mL). Hydroxylamine hydrochloride (5.01 g, 72.2 mmol) was added and the mixture was heated to 85° C. Acetic anhydride (40 mL) was added and the reaction was stirred at 85° C. for 3 h, after which time the solvent was evaporated at 40° C. under reduced pressure. The residue was dissolved in water, basified with 2.0 N NaOH solution to pH 9, and extracted with 4:1 dichloromethane/2-propanol until the pyridine was completely removed (5×200 mL). The aqueous solution was then acidified with 2.0 N HCl solution to pH 2, saturated with solid NaCl, and extracted with 4:1 dichloromethane/2-propanol (5×200 mL). The combined organic extracts were dried over Na2SO4 and concentrated in vacuo to dryness. The residue was crystallized from dichloromethane to give 6.80 g of the title compound as a white solid (76%). Mass spectrum (ESI-neg, m/z) Calcd. for C6H3NO3, 136.0 (M−H). found 136.1. The 1H NMR spectrum was consistent with the assigned structure.

1. customA 250-mL, three-neck, round-bottom flask equipped with a mechanical stirrer
2. customafter which time the solvent was evaporated at 40° C. under reduced pressure
3. dissolutionThe residue was dissolved in water
4. extractionextracted with 4:1 dichloromethane/2-propanol until the pyridine
5. customwas completely removed (5×200 mL)
6. extractionextracted with 4:1 dichloromethane/2-propanol (5×200 mL)
7. dry with materialThe combined organic extracts were dried over Na2SO4
8. concentrationconcentrated in vacuo to dryness
9. customThe residue was crystallized from dichloromethane

ORD record

ord-cbffed0def6a4fa5b9c4db16cb59033e

Source dataset

uspto-grants-2015_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08933091B2