A.
2-(Trichloromethyl)bicyclo[3.3.0]octane. To a
5-l. three-necked flask equipped with a
mechanical stirrer, a
reflux condenser, and a
thermometer are added
325 g. (3.0 moles) of cis,cis-1,5-cyclooctadiene (Note
1),
3 l. of chloroform (Note
2), and
14.6 g. (0.06 mole) of benzoyl peroxide. The resulting solution is stirred and refluxed (63–65°) on the
steam bath (Note
3) for a total of 5 days. Four
7.3 g.-(0.03 mole-)portions of benzoyl peroxide are added, one on each consecutive day of reaction (Note
4). After a total of 5 days at reflux, the reaction mixture is cooled and washed with three
250-ml. portions of aqueous sodium bicarbonate (Note
5) and with 250 ml. of water, all the washes being discarded. The
chloroform solution is dried with
30 g. of magnesium sulfate and filtered. The filtrate is distilled at atmospheric pressure using a
short (8-in.) Vigreux column to collect
2760–2790 ml. of chloroform, b.p.
55–64°, which is discarded. The pressure is reduced and distillation continued to obtain two fractions: (1) b.p. 31° (47 mm.) to 65° (0.2 mm.), 300 g.; (2) b.p. 65–153° (0.2 mm.), 169 g. (Note
6). Fraction 2 is refractionated with the same Vigreux column to obtain
106–117 g. (approximately
35% based on unrecovered
cis,cis-1,5-cyclooctadiene) of
2-(trichloromethyl)bicyclo[3.3.0]octane, b.p.
116–125° (5 mm.),
n25D 1.5110–1.5115 (Note
7). The product is pure (by gas chromatography) (Note
8) and may be used in the next step.