A
250-ml. three-necked round-bottomed flask is fitted with a dropping funnel, a mechanical stirrer, and a steam-jacketed column (15–20 cm. long) terminating in a still head. The still head carries a
thermometer and is connected to a
condenser set for downward distillation. In the flask are placed
42.2 g. (0.22 mole) of ethyl benzoylacetate (Note
1) and
50 ml. of dry xylene, and the flask is immersed in an
oil bath. The bath is heated to 145–150°, stirring is begun, and
18.2 ml. (18.6 g., 0.20 mole) of aniline is added dropwise during 30 minutes. About 5 minutes after the addition has begun, the temperature in the still head rises to 75–78° as
ethanol begins to distil. Approximately 12–14 ml. of distillate (Note
2) is collected in a 25-ml. graduate in about 1 hour; the end of the reaction is indicated by the fall of the temperature in the still head.
The reaction flask is removed from the
oil bath, and the solution is poured into a
250-ml. beaker to crystallize;
10 ml. of benzene is used to rinse out the flask. When crystallization sets in,
50 ml. of petroleum ether (b.p.
35–55°) is added to the warm mixture with manual stirring. After the mixture has been chilled in an
ice bath, the product is filtered by suction and washed with
100 ml. of a 1:1 petroleum ether-benzene mixture. It is then removed from the funnel, stirred into a slurry with 100 ml. of the mixed solvent, filtered, and again washed with 50 ml. of the solvent. These washings remove the bulk of the color, and a powdery white product remains. After standing overnight in a warm place, the product weighs
35.5–36.5 g. (
74–76%) and melts at
104–105°. It may be purified further by recrystallization from
benzene (3.7 ml. per g.). The yield of colorless
benzoylacetanilide melting at
106–106.5° cor, is
32–34 g.