Phosphorus oxychloride → 3-Methyl-5-phenyl-2,4-pentadienoic acid

Participants

Reaction Steps

Dimethylformamide (DMF, anhydrous, 25 mL) was cooled to 0–5° C. and phosphorus oxychloride (16.4 mL) was added dropwise over a period of an hour. The resulting solution was added dropwise to a cooled (0–5° C.) solution of 4-phenyl-2-methyl-3-buten-2-ol (0.14 mol) in 60 mL of anhydrous DMF over a period of an hour. The reaction mixture was then warmed to room temperature, gradually heated up to 80° C., stirred at 80° C. for three hours and cooled to 0–5° C. To the cooled reaction solution was added dropwise a solution of sodium acetate (80 g) in deionized water (190 mL) over a period of two hours. The mixture was then reheated to 80° C., stirred at 80° C. for an additional 10 minutes, cooled down to room temperature and extracted with ether (300 mL) twice. The combined extract was washed with water (200 mL), dried over anhydrous sodium sulfate, filtered and concentrated in vacuum to yield 16.7 g of the desired 3-methyl-5-phenyl-2,4-pentadienal as a liquid which was used in the next step without further purification.

Provenance & Evidence