In a
500-ml. three-necked round-bottomed flask equipped with a
dropping funnel, a sealed
mechanical stirrer, and an air condenser is placed
150 ml. of Dowtherm (Note
1). The
Dowtherm is stirred and heated at the reflux temperature while
65 g. (0.32 mole) of ethyl β-anilinocrotonate (p. 374) is added rapidly through the dropping funnel. Stirring and refluxing are continued for 10–15 minutes after the addition is completed. The
ethanol formed in the condensation reaction may be allowed to escape from the condenser through a tube leading to a drain, or it may be collected by attaching a
water-cooled condenser set for distillation to the top of the air condenser. The mixture is allowed to cool to room temperature, at which stage a yellow solid separates. Approximately
200 ml. of petroleum ether (b.p.
60–70°) is added; the solid is collected on a
Büchner funnel and washed with
100 ml. of petroleum ether (b.p.
60–70°). After air drying, the crude product is treated with
10 g. of Darco or Norit in 1 l. of boiling water (Note
2). The hot solution is filtered and allowed to cool. The white, hairlike needles of
2-methyl-4-hydroxyquinoline are separated by filtration. The yield of product, melting at
235–236° (cor.), is
43–46 g. (
85–90%).