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).