In a
1-l. Erlenmeyer flask provided with a
mechanical stirrer are placed
75 g. (1 mole) of glycine (Org. Syn. Coll. Vol. I, 1941, 298) and 300 cc. of water. The mixture is stirred vigorously until the
glycine is almost completely dissolved, when
215 g. (2 moles) of 95 per cent acetic anhydride (Note
1) is added in one portion. Vigorous stirring is continued for fifteen to twenty minutes, during which time the solution becomes hot and
acetylglycine may begin to crystallize. The solution is placed in the
refrigerator (Note
2) overnight to effect complete crystallization. The precipitate is collected on a
Büchner funnel, washed with ice-cold water, and dried at 100–110°. This product weighs
75–85 g. and melts at
207–208°. The combined filtrate and washings are evaporated to dryness under reduced pressure on a
water bath at 50–60°. The residue on recrystallization from 75 cc. of boiling water yields a second fraction, of
20–30 g., which melts at
207–208° after being washed with ice-cold water and dried at 100–110°. An additional
4–6 g. of only slightly less pure product may be obtained from the mother liquor by concentration. The total yield is
104–108 g. (
89–92 per cent of the theoretical amount) (Note
3).