Water → 6-fluoro-4-oxo-3,4-dihydro-2H-1-benzopyran-2-carboxylic acid

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Reaction Steps

A solution of 6-fluoro-3,4-dihydro-4-oxo-2H-1-benzopyran-2-carbonitrile (78.3 g, 0.41 mol)(obtained through the process as described in said Item (c) in 760 ml of concentrated hydrochloric acid was heated at reflux temperature for 50 minutes. After cooling the reaction solution, 700 ml of water and 1 liter of ethyl acetate were added to carry out an extraction. Resulting organic layer was evaporated in vacuo to dryness. To the residue, 700 ml of saturated sodium biscarbonate was added and stirred for 30 minutes. The aqueous basic solution was washed with 500 ml of ethyl acetate, acidified with 6N-hydrochloric acid and extracted with 1 liter of ethyl acetate. The organic layer was washed with water, dried over anhydrous sodium sulfate, filtered and evaporated in vacuo to give 76.9 g (89.3%) of the desired compound.

Provenance & Evidence