In a
3-l. three-necked round-bottomed flask, equipped with a
mercury-sealed stirrer and a
12-bulb reflux condenser, are placed
188.5 g. (1 mole) of p-chlorobiphenyl (Note
1),
47.2 g. (0.4 mole) of ethyl carbonate (Note
2), and
1.5 l. of anhydrous, thiophene-free benzene. The side tube is closed with a cork, stirring is begun, and the mixture is heated by means of a hot plate (Note
3). As soon as the mixture begins to boil,
2 g. of powdered sodium (Note
4) is added. The reaction starts in 1–2 minutes, as indicated by more vigorous refluxing and a change in color from yellow to brown (Note
5). Powdered
sodium is then introduced in small portions, over a period of 1 hour, until an additional 28 g. has been added (total amount of sodium, 30 g.). The reaction mixture is refluxed and vigorously stirred (Note
6) for 2 hours. When the mixture has cooled somewhat,
75 to 100 ml. of absolute ethanol is added. After all the particles of
sodium have reacted, 500 ml. of water is added, the condenser is arranged for downward distillation, and the
benzene and unchanged
p-chlorobiphenyl are removed by distillation from a
steam bath (Note
7). The crude product remaining in the flask is separated by filtration, washed with 100–200 ml. of water, and pressed as dry as possible. The solid is dissolved in
600 ml. of xylene in a
1-l. distilling flask, and the solution is subjected to distillation until 25 to 50 ml. of distillate (
xylene and water) has been collected. The solution is cooled somewhat,
1 to 2 g. Norit is added, and then the mixture is boiled for 5 minutes. The hot solution is filtered rapidly and the filtrate is cooled. The product is collected by filtration, washed with
25 to 50 ml. of cold xylene then with
200 ml. of petroleum ether, and dried. The
tribiphenylcarbinol forms small white crystals which melt at
207–208°. The product weighs
57–65 g. (
35–40%) (Note
8).