Acetic Anhydride → 2-Bromo-n-valeramide

A stirred solution of 100 g. (0.55 mole) of 5-bromovaleramide, 62.4 g. (0.61 mole) of acetic anhydride, and 5.4 g. (0.055 mole) of concentrated sulfuric was heated on a steam bath under nitrogen for 1.5 hours (internal temperature 93°). The mixture was then cooled to room temperature diluted with 250 ml. of water. The resultant tan granular precipitate was collected by filtration and dissolved in 600 ml. of methylene chloride. The solution was washed with saturated sodium bicarbonate (100 ml.) and saturated brine (100 ml.), was dried (anhydrous magnesium sulfate), treated with Darco, and filtered. Hexane was added to effect crystallization which afforded 64.8 g. (53.0% yield) of N-acetyl-5-bromovaleramide melting at 88°-90° .