Sodium Hydroxide → 2,5-Dimethylthiophene-3-carboxylic acid

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Reaction Steps

Phosphorus oxychloride (10 ml) was slowly added dropwise to dimethylformamide (30 g) under ice-cooling, and 2,5-dimethylthiophene (11.2 g) was added. The mixture was stirred at 100° C. for 15 hours, poured into water and extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to give 2,5-dimethyl-3-thiophenecarbaldehyde (1.41 g). 2,5-Dimethyl-3-thiophenecarbaldehyde (3.89 g) synthesized in this manner was dissolved in acetonitrile (30 ml), and sodium dihydrogen phosphate (1.2 g) in water (15 ml) and 30% aqueous hydrogen peroxide (3.5 ml) were added dropwise. The mixture was stirred at room temperature for 2 hours, alkalified with 1N aqueous sodium hydroxide and washed with diethyl ether. The aqueous layer was acidified with 1N hydrochloric acid and extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give 2,5-dimethyl-3-thiophenecarboxylic acid (4.09 g) as crystals.

Provenance & Evidence