Pyrazole → Benzoic acid, 4-(3-chloropropoxy)-3-methoxy-

Participants

Reaction Steps

To a stirred suspension under nitrogen of sodium hydride (6.4 g, 130 mmol, of about 50% oil dispersion-ether washed) in tetrahydrofuran (220 ml) was added pyrazole (4.4 g, 60 mmol) in tetrahydrofuran (60 ml), dropwise. After complete addition, the reaction was stirred for about 15 minutes, and then 4-(3-chloropropoxy)-3-methoxybenzaldehyde (24.5 g, 107 mmol) was added. The nitrogen was stopped and air was sparged into the reactor for about 3 hours. The reaction was then allowed to stir at ambient temperature open to the atmosphere for 6 hours. Water was added, the reaction was cooled in an ice bath, and concentrated hydrochloric acid (25 ml) was added dropwise. More water was added and the yellow solid that separated was collected to afford 16.2 g of product. The filtrate was then extracted with ethyl acetate to afford an additional 9.3 g. The samples were combined and recrystallized from acetonitrile to yield 12.6 of a light, yellow solid, m.p.=154°-156° C. A 4.0 g sample was recrystallized from acetonitrile to yield 2.6 g of a yellow solid. This combined with 0.4 g from another sample and recrystallized again from acetonitrile with charcoal treatment to afford 2.0 g of 4-(3-chloropropoxy)-4-methoxybenzoic acid as a yellow solid, m.p.=157°-159° C.

Provenance & Evidence