In a
5-l. three-necked, round-bottomed flask, fitted with a
mechanical stirrer,
dropping funnel, and a
condenser connected to an apparatus for removing
hydrogen chloride, are placed
858 g. (980 cc., 11 moles) of dry benzene (Note
1) and
464 g. (3.48 moles) of aluminum chloride. The reaction mixture is cooled in an
ice bath to 10°, and then
405.1 g. (3 moles) of commercial sulfur chloride in 390 g. (450 cc., 5 moles) of benzene is added, with stirring, over a period of one hour, the temperature being kept at about 10°. The reaction begins at once as evidenced by the evolution of
hydrogen chloride and the separation of a yellow viscous aluminum chloride complex. When all the
sulfur chloride has been added, the reaction mixture is removed from the ice bath, stirred at room temperature for two hours, and then heated at 30° until practically no
hydrogen chloride is evolved (one hour). The mixture is then poured on 1 kg. of cracked ice, and, when hydrolysis is complete, the
benzene layer is separated from the water layer by means of a
separatory funnel. The
benzene is distilled on a
steam bath, and the resulting dark-colored oil is cooled to 0° and filtered through a
Büchner funnel to remove the
sulfur which separates. The residue is dissolved in
500 cc. of commercial methyl alcohol, and the solution is cooled to 0°. Stirring is continued for three hours, and the precipitated
sulfur is removed as before. The alcohol is removed on a steam bath, and the residue is distilled from a
1-l. modified Claisen flask with a
water-cooled side-arm receiver. After a small amount of low-boiling product passes over, there is obtained
470–490 g. (Note
2) of a yellow liquid boiling at
155–170°/18 mm. The material thus obtained is heated for one hour on a steam bath, with stirring, with
70 g. of zinc dust and
200 g. of 40 per cent sodium hydroxide solution (Note
3). The
diphenyl sulfide is then separated from the
sodium hydroxide, washed with two 500-cc. portions of water, dried over anhydrous
sodium sulfate, and distilled. The yield of colorless
diphenyl sulfide boiling at
162–163°/18 mm. is
450–464 g. (
81–83 per cent of the theoretical amount).