A
2-l., three-necked flask equipped with a mechanical stirrer, a reflux condenser fitted with a calcium chloride drying tube, and a pressure-equalizing dropping funnel is charged with
53.4 g. (0.400 mole) of anhydrous aluminum chloride (Note
1) and
800 ml. of dichloromethane (Note
2). The flask is placed in an
acetone–dry ice bath, and the mixture is stirred for a few minutes before slowly adding a solution of
36.9 g. (0.200 mole) of (4-methoxyphenyl)acetyl chloride (Note
3) in
200 ml. of dichloromethane over 45 minutes. When the addition is complete, the funnel is replaced with a
gas-inlet tube (Note
4), and
ethylene is bubbled vigorously into the flask for about 10 minutes. The gas-inlet tube is replaced with a stopper, the
cooling bath is removed, and the reaction mixture is allowed to warm to room temperature, then stirred for 3–3.5 hours (Note
5). The reaction mixture is cooled in an
ice bath while 250 ml. of ice water is added
carefully (Note
6). The mixture is stirred until all of the solid material is dissolved. The yellow organic layer is separated, washed two times with
150-ml. portions of 5% hydrochloric acid and two times with
150-ml. portions of saturated sodium hydrogen carbonate. The organic layer is dried over
magnesium sulfate and filtered. The solvent is distilled with a rotary evaporator, keeping the bath temperature under 60°. Distillation (Note
7) of the yellow residue through a
15-cm. Vigreux column gives
21–24 g. (
60–68%) of
6-methoxy-β-tetralone, b.p.
114–116° (0.2 mm.), which solidifies to a white solid on standing in the refrigerator, m.p.
33.5–35° (Note
8).