Reaction #543536

Reaction equation

5-chloro-2-hydroxybenzamide

pyridine

hydrochloric acid

Ethyl chloroformate

→

6-chloro-2H-1,3-benzoxazine-2,4(3H)-dione

Yield 85.3%

Solvents

water

acetonitrile

Conditions

Workup

1. 1
   workup.DISTILLATIONthe volatiles were distilled off (43 ml)
2. 2
   TemperatureThe reaction was cooled to room temperature
3. 3
   Otherto form
4. 4
   FiltrationThe resulting solid was filtered
5. 5
   Otherrecrystallized in hot ethanol

Procedure

A solution of 10 g of 5-chloro-2-hydroxybenzamide (58.0 mmol), pyridine (22 ml) and acetonitrile (25 ml) was stirred in an ice bath. Ethyl chloroformate (6.1 ml, 0.0638 mol) was added dropwise. The pink solution was stirred for 30 minutes at <10° C. The ice bath was replaced with an oil bath. The reaction mixture was heated to 95° C. and the volatiles were distilled off (43 ml). The reaction was cooled to room temperature, causing a white solid to form. The mixture was poured into water (100 ml) and acidified with concentrated aqueous hydrochloric acid. The resulting solid was filtered and recrystallized in hot ethanol to give 9.77 g of 6-chloro-2H-1,3-benzoxazine-2,4(3H)-dione.

Source