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Org. Synth. 1928, 8, 22
DOI: 10.15227/orgsyn.008.0022
BENZALANILINE
[Aniline, N-benzylidene-]
Submitted by Lucius A. Bigelow and Harry Eatough.
Checked by Henry Gilman and J. D. Robinson.
1. Procedure
In a 500-cc. three-necked, round-bottomed flask provided with a mechanical stirrer is placed 106 g. (1 mole) of benzaldehyde (Note 1), and 93 g. (1 mole) of aniline is added with rapid stirring. After a few seconds a reaction occurs with evolution of heat and separation of water. The mixture is allowed to stand fifteen minutes and is then poured, with vigorous stirring, into 165 cc. of 95 per cent alcohol in a 600-cc. beaker. Crystallization begins in about five minutes, and the mixture is allowed to stand, first ten minutes at room temperature, and then thirty minutes in ice water. The almost solid mass is next transferred to a large Büchner funnel, filtered by suction, pressed out, and air-dried. The yield of pure benzalaniline melting at 52° is 152–158 g. (84–87 per cent of the theoretical amount).
By concentrating the mother liquor to about one-half of its original volume at room temperature or lower, under reduced pressure by means of a water pump, an additional 10 g. of benzalaniline may be obtained. This is of good quality and melts at 51° (Note 2).
2. Notes
1. Freshly distilled reagents must be used to obtain the yields described. Distillation through a column is recommended. The benzaldehyde should be washed with 5 per cent sodium carbonate solution before being distilled under reduced pressure with minimum atmospheric exposure.
2. Removal of the alcohol by distillation at ordinary pressure gives a much darker product.
If a product of high purity is desired, it may be obtained by recrystallization from 85 per cent alcohol.
3. Discussion
Benzalaniline can be prepared from aniline and benzaldehyde1 either without a solvent or in dilute alcohol saturated with carbon dioxide.2

References and Notes
  1. Laurent and Gerhardt, Jahresber. 488 (1850); Bogert, Org. Syn. 5, 13 (1925).
  2. Pyl, Ber. 60, 287 (1927).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

alcohol (64-17-5)

aniline (62-53-3)

sodium carbonate (497-19-8)

carbon dioxide (124-38-9)

benzaldehyde (100-52-7)

Benzalaniline,
Aniline, N-benzylidene- (538-51-2)