Phosphorus oxychloride → 6-CHLORO-5-NITRONICOTINIC ACID

Participants

Reaction Conditions

Reaction Steps

A suspension of 6-hydroxy-5-nitronicotinic acid (8 g, 43.5 mmol) (prepared by literature nitration of 6-hydroxynicotinic acid) in phosphorus oxychloride (24.3 mL, 261.0 mmol) was heated to reflux (105° C.) for 3 h under a nitrogen atmosphere. At the end of this time period all of the solids had dissolved. The reaction was cooled to rt and poured over 500 mL crushed ice, and stirring was continued for 30 minutes until all of the ice had melted. The aqueous mixture was extracted with a 1:2 mixture of THF in diethyl ether (3×150 mL). The pooled organic extracts were washed with brine (1×), dried (MgSO4), and concentrated on a rotary evaporator to afford intermediate 56 as a light brown solid (8.37 g, 95%). ESI-MS m/e 405.3 (2M−1).

Provenance & Evidence