cis-1,2-Dichloro (CAS NO.: ), which is also known as Cyclohexane, 1,2-dichloro-, cis-, could be produced through the following synthetic routes.

A 1-l., three-necked flask is charged with 95 g. (0.36 mole) of triphenylphosphine and 500 ml. of anhydrous , and fitted with a gas-inlet, a mechanical stirrer, and a condenser with attached drying tube. The flask is cooled in an ice bath, stirring is begun, and chlorine is introduced through the gas-inlet. Dichlorotriphenylphosphorane separates as a white solid or as a milky oil; the flow of chlorine is discontinued when the mixture develops a strong lemon-yellow color. The gas inlet is quickly replaced by an addition funnel, and a solution of 10 g. of triphenylphosphine in 60 ml. of benzene is added dropwise fairly rapidly. A solution of 24.5 g. (0.250 mole) of 1,2-epoxycyclohexane in 50 ml. of benzene is then added dropwise over ca. 20 minutes. The ice bath is replaced by a heating mantle, and the mixture, which consists of two liquid phases, is stirred and refluxed for 4 hours. It is then cooled, and excess dichlorotriphenylphosphorane is destroyed by the slow addition of 10 ml. of methanol. The mixture is concentrated on a rotary evaporator at ca. 100 mm., and the residue, which may be a white solid or a viscous oil, is triturated with 300 ml. of petroleum ether (30–60°). The solid that separates is collected by suction filtration. The cake is thoroughly broken up with a spatula and washed with three 100-ml. portions of petroleum ether. The combined filtrates, from which a little more triphenylphosphine oxide precipitates, are refiltered, then washed with 250-ml. portions of aqueous 5% sodium bisulfite and with water. The organic phase is dried over magnesium sulfate, filtered, concentrated on a rotary evaporator at ca. 100 mm., and distilled through a 20-cm. Vigreux column. There is very little forerun before 27–28 g. (71–73%) of cis-1,2-dichlorocyclohexane is collected at 105–110° (33 mm.), n_D25 1.4977.

Benzene has been identified as a carcinogen. OSHA has issued emergency standards on its use. All procedures involving benzene should be carried out in a well-ventilated hood, and glove protection is required. A hood should be employed for the chlorination.