Hydrochloric Acid → 4-Hydroxy-7-methylcoumarin

Participants

Reaction Steps

A solution of 42 g (0.28 mol) of 4-methyl-2-hydroxyacetophenone in benzene (150 mL) was added over 30 min., to a suspension of NaH (50% oil), (30 g, 0.63 mol) in 400 mL of benzene at reflux. Then diethylcarbonate (67.8 mL, 0.56 mol) in benzene (500 mL) was added over 15 min. The reaction mixture was refluxed for 16 h and more NaH (13 g, 0.28 mol) was added followed by more diethylcarbonate (33 g, 0.28 mol). After another 6 h at reflux the reaction mixture was cooled to room temperature and 2N HCl was added (1.5 L) to form a white precipitate. The solid was then filtered and added to a solution of NaOH (4N, 800 mL). The resulting basic solution was then extracted with Et2O (2×500 mL) and the basic solution acidified with conc. HCl to give a white solid which, after filtration and drying, gave the title compound.

Provenance & Evidence