Org. Synth. 1940, 20, 66
DOI: 10.15227/orgsyn.020.0066
[Formanilide, N-methyl-]
Submitted by L. F. Fieser and J. E. Jones.
Checked by C. F. H. Allen and J. VanAllan.
1. Procedure
In a 3-l. round-bottomed flask fitted with a 3-ft. indented column to which is attached a condenser set for downward distillation are placed 321 g. (3 moles) of methylaniline, 300 g. of formic acid (85–90%), and 1.8 l. of toluene (Note 1). The solution is distilled slowly. As long as the azeotrope containing water is present, the temperature of the vapor is 87–88°; when the water has been removed, the temperature rises to 108–110° (Note 2). The distillation is continued until approximately 1.5 l. of toluene has been collected (5–6 hours). The residue is then transferred to a modified Claisen flask and distilled under reduced pressure, the portion boiling at 114–121°/8 mm. being collected. This has a freezing point of 13.6–13.7°; n29D 1.553–1.555. The yield is 380–393 g. (93–97%). This product is satisfactory for the preparation of aldehydes. Upon redistillation it boils at 117–121°/8 mm., 130–132°/22 mm. The freezing point and refractive index are unchanged (Note 3).
2. Notes
1. The toluene serves to remove the water and minimize side reactions.
2. The water layer of the distillate is separated; it amounts to 140–150 ml.
3. If a water separator with a stopcock is employed, in such a way that the organic solvent is returned to the reaction flask, it is possible to use 200 ml. of benzene in place of the 1.8 l. of toluene (J. Meek, private communication).
3. Discussion
N-Methylformanilide has been obtained in a yield of 67.5% by heating methylaniline with formamide in glacial acetic acid solution.1 The method above is a modification of that of Morgan and Grist,2 who heated the amine and formic acid in the absence of a solvent or water-carrier (the present authors obtained a yield of only 40–50% by that procedure).
This preparation is referenced from:

References and Notes
  1. Hirst and Cohen, J. Chem. Soc., 67, 830 (1895).
  2. Morgan and Grist, J. Chem. Soc., 113, 690 (1918).

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

acetic acid (64-19-7)

Benzene (71-43-2)

formamide (75-12-7)

formic acid (64-18-6)

toluene (108-88-3)

methylaniline (100-61-8)

Formanilide, N-methyl- (93-61-8)