Ammonium Hydroxide → 4-(2-Bromotetrafluoroethoxy)benzamide

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Reaction Steps

4-(2-Bromotetrafluoroethoxy)benzoic acid prepared as in Example 18 (26.6 g, 0.083 mol) is transferred to a 250 mL round-bottomed flask along with 150 mL of methylene chloride. Oxalyl chloride (11.64 g, 0.92 mol) is added and the mixture is stirred under nitrogen overnight to form a turbid solution which is concentrated by rotary evaporation and distilled at 80°-90° C./0.1 mmHg to yield 20.88 g of 4(2-bromotetrafluoroethoxy)benzoyl chloride as a colorless liquid, leaving 6.16 g of unreacted acid (76.8% conversion, 96.5% yield). The benzoyl chloride is added slowly with stirring to 8 mL of cold ammonium hydroxide (0.12 mol). The product amide precipitates as fine white needles which are filtered and dried under vacuum to yield 14.74 g of 4-(2-bromotetrafluoroethoxy)benzamide (75% conversion, 99% yield, m p. 150.5°-151.5° C.), along with 4.8 g of 4-(2-bromotetrafluoroethoxy)benzoic acid which is recovered from the mother liquor (24.3% recovery).

Provenance & Evidence