A
500-ml. flask is equipped with a capillary through a side opening, and
94 g. (1.01 moles) of aniline and
1 ml. of concentrated hydrochloric acid are added. A
12-in. glass-helix-packed column is attached (Note
1), and the water introduced with the acid is removed by boiling; about
1 ml. of aniline is collected after the water has distilled. The flask and its contents are then cooled to room temperature, and
222 g. (1.50 moles) of ethyl orthoformate is added. The column is reattached, and
ethanol (Note 2) is distilled as it is produced; the theoretical amount (92 g., 116 ml.) is obtained in about 2.25 hours.
The reaction mixture is allowed to cool slightly, and the pressure is lowered to 40 mm. (Note
3). The excess
ethyl orthoformate is distilled at 65°/40 mm. After a small intermediate fraction of about 4 g., b.p. 65–117°/40mm., the product distils at
117–118°/40mm. (b.p.
87–88°/10mm.;
nD25 1.5248); the yield is
118–127 g. (
78–84%). The residue amounts to about
14 g. and is mainly
N,N'-diphenylformamidine (Note
4).