B.
1,2-Bis(n-butylthio)benzene. In a
1-l., round-bottomed, three-necked flask fitted with a
reflux condenser, a
mechanical stirrer, and a
thermometer which reaches into the reaction mixture is placed a solution of
59.0 g. (0.25 mole) of o-dibromobenzene in a mixture of
250 ml. of quinoline and
80 ml. of pyridine. To this solution is added
84.0 g. (0.55 mole) of cuprous n-butylmercaptide, and the mixture is stirred and heated under reflux (Note
5) for 3.5 hours (Note
6). Heating is stopped and the reaction mixture is allowed to cool to about 100°. It is then poured into a stirred mixture of 1500 g. of ice and
400 ml. of concentrated hydrochloric acid; occasional stirring is continued for about 2 hours. The aqueous part is then decanted from the dark brown, gummy residue and is extracted twice with
400 ml. portions of ether. The
ether extract is added to the residue, and the resulting mixture is stirred for about 5 minutes. The
ether solution is then decanted from the residue and is filtered. The residue is extracted twice more with
400-ml. portions of ether (Note
7). The combined
ether extract is washed twice with
100-ml. portions of 10% hydrochloric acid, once with water, and twice with
100-ml. portions of concentrated ammonia (Note
8). After a final wash with water, the
ether solution is dried over anhydrous
potassium carbonate. The
potassium carbonate is collected on a filter, and the
ether is removed from the filtrate by distillation. The remaining brown oil is distilled in vacuum, giving a pale orange oil, b.p.
123–124°/0.3 mm.,
nD25 1.5684. The yield is
46.5–56.0 g. (
73–87%) (Note
9).