Submitted by Saul R. Buc
Checked by Homer Adkins and James M. Caffrey.
1. Procedure
The reactions are carried out in
1-l. heavy-walled bottles provided with
rubber stoppers which must be wired securely in place (Note
1). In each of four bottles are placed
400 ml. of concentrated ammonium hydroxide (28–30% ammonia) and
100 ml. (80 g., 1.5 moles) of cold acrylonitrile (Note
2). The rubber stoppers are immediately wired in place (Note
3). Each bottle is then shaken intermittently until after about 5 minutes the reaction mixture becomes homogeneous. Thereupon, the bottle, wrapped in a towel, is immediately set away under a hood (Note
4).
The reaction mixtures are allowed to stand a few hours or overnight and then are transferred to a
3-l. flask. The water and
ammonia are distilled under reduced pressure as rapidly as possible until the boiling point is about 50°/20 mm. (Note
5). The higher-boiling products (395 g.) are then transferred to a
1-l. Claisen flask and fractionated under reduced pressure.
The crude primary amine (
138–149 g.) is distilled over the range 75–110°/21 mm. (Note
6), and the crude secondary amine (
213–226 g.) in the range 130–150°/1 mm. The primary amine, b.p.
79–81°/16 mm. or 87–89°/20 mm. (
nD20 1.3496), after refractionation, is obtained in a yield of
130–140 g. (
31–33%) (Note
7). The secondary amine, b.p.
134–135°/1 mm. (
nD20 1.4640), is obtained in a yield of about
210 g. (
57%) (Note
8).
2. Notes
1. The
1-l. centrifuge bottles (Corning No. 1280) carrying No. 6 rubber stoppers, as used for catalytic hydrogenation, are suitable for carrying out reactions under pressures up to at least 3 atm. The submitter used a heavy, selected
2-l. round-bottomed flask instead of the four bottles specified in the procedure above.
2. The
acrylonitrile should be free of polymer. If there is uncertainty as to its quality, the
acrylonitrile should be redistilled.
3. The temperature of the mixture does not rise during the period of solution of the
acrylonitrile in the
ammonium hydroxide. However, almost immediately thereafter the temperature of the solution begins to rise slowly, reaching a value of about 65° after an interval of perhaps 10 minutes. There is no significant rise in pressure within the bottle until the temperature of the reaction mixture begins to rise. The maximum pressure reached is apparently less than 2 atm.
4. The checkers placed the wrapped bottles within a 10-gal crock located under a hood. There is no danger that the bottles will be broken by the pressure developed. However, if a stopper is not firmly held, it may be pushed out, in which event a portion of the reaction mixture will foam out of the bottle.
5. The submitter used a special apparatus suitable for the rapid evaporation of water under reduced pressure. The checkers used standard flasks. Better yields result from the rapid removal of water.
6. It is not necessary to purify the crude primary amine by redistillation if it is to be used immediately for the preparation of
β-alanine. However, the moist nitrile is not stable in storage, pressure being developed in a container stored at room temperature.
7. Yields of
60–80% of the primary amine
1 have been obtained by introducing the
acrylonitrile below the surface of the aqueous
ammonia preheated at 110° in a steel reactor suitable for pressure reactions.
3. Discussion
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