Preparation
CAUTION: This chloride is explosive, and the solvent has to be removed under reduced pressure.
To a 500-ml, three-necked flask equipped with a mechanical stirrer, thermometer, gas addition tube, and condenser is added 200 ml of dry carbon tetrachloride, 30 gm (0.1 mole) of 2,2'-dinitrophenyl disulfide, and 0.05 gm of iodine as a catalyst. The suspension is heated to 50-60°C, and chlorine gas is added at such a flow rate that 10 gm (0.14 mole) is added over a 2-2^-hr period at this temperature. After this time, the solid starting disulfide finally goes into solution, and the warm dark yellow solution is filtered. The solution is cooled to 5°C, and the product that crystallizes out is filtered and dried to afford 25.2-27.0 gm (66-71%), m.p. 73-74.5°C.
Purification Methods
Recrystallise it from CCl4 (2mL/g), filter off the solution at 5o (recovery 75%). It has also been recrystallised from pet ether (b 40-60o), dried rapidly at 50o and stored in a brown glass bottle, sealed well and stored away from moisture. [Hubacher Org Synth Coll Vol II 455 1943, Ito et al. Chem Pharm Bull Jpn 26 296 1978, Beilstein 6 I 157.]
