Hydrochloric Acid → 4-Hydroxy-7-methylcoumarin

Participants

Reaction Steps

A solution of 42 g (0.28 mol) of 2-hydroxy-4-methylacetophenone 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 s 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 r.t. and HCl (2N) 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 HCl conc. to give a white solid which after filtration and dried gave 38.7 g (79%) of the title compound.

Provenance & Evidence