A.
"Acetone-anil" (Note
1). A mixture of
279 g. (3 moles) of aniline and
9 g. of iodine is placed in a
1-l. three-necked round-bottomed flask. The flask is fitted with a
dropping funnel (the
delivery tube of which extends below the liquid surface), a
mercury-sealed stirrer (Note
2), and an adapter carrying a
thermometer which extends into the liquid and a condenser system such that most of the
aniline will return and all the water produced (as well as excess
acetone) will distil (Note
3). The flask is now heated in an
oil bath (Note
4) and (Note
5), and the reaction mixture is maintained at 170–175° while
acetone is passed in through the dropping funnel at such a rate that no more than 2 drops of liquid distils per second. During the addition the mixture is vigorously stirred. A total volume of
850 ml. (670 g., 11.6 moles) of acetone is added over a 4-hour period, and about 610 ml. of distillate is collected. At the end of this period the reaction mixture is cooled and distilled in vacuum, three fractions being collected (up to 136°/15 mm., 136–141°/15 mm., and 141–146°/15 mm.). The
acetone-water distillate is now distilled through a simple column at atmospheric pressure until essentially all the
acetone has come over. There remains a mixture of oil and water which is separated after being cooled. The oil is then used as the first fraction for a fractional distillation in vacuum of the reaction product, each of the previous fractions being added in succession. Three new fractions are collected:
78–82°/13 mm. (a little
aniline); 82–133°/13 mm. (a small intermediate fraction); and
133–138°/13 mm. (
acetone-anil). An appreciable quantity of tarry residue remains in the distillation flask. The yield based upon
aniline actually consumed in the reaction is
61–68% (Note
5).