Malonic Acid → 8-Ethyl-4-hydroxy-2H-1-benzopyran-2-one

Participants

Reaction Steps

A mixture of 2-ethylphenol (Aldrich) (6.1 g; 50 mmole), malonic acid (Aldrich) (5.2 g; 50 mmole), zinc chloride (20.4 g, 150 mmole) and phosphorous oxychloride (Merck) (14 mL; 150 mmole) was heated under stirring for 24 hours at 70–75° C., whereupon the reaction was stopped and a mixture of water and ice was added. The reaction mixture was stirred for further 2 hours at room temperature and then 10% sodium carbonate (150 mL) was added to the filtered brown precipitate while stirring. The insoluble part was filtered and the filtrate was acidified with concentrated hydrochloric acid, whereat a brown precipitate was precipitated, which was then filtered and washed with cold water. By recrystallization from 50% ethanol there were obtained 2.29 g (24%) of brown powdery 8-ethyl-4-hydroxycoumarin.

Provenance & Evidence