A 2-l. round-bottomed, short-necked flask is equipped with a glass mechanical stirrer. A suspension of 165 g. (0.5 mole) of o-chloromercuriphenol (p. 161) (m.p. 147° or higher) in 500 cc. of chloroform is placed in the flask and treated with 127 g. (0.5 mole) of iodine, the stirring being continued until a small sample on filtration shows no unreacted iodine. This requires from one to two hours. The solid inorganic mercury compounds are removed by suction filtration. The filtrate is distilled from a 1-l. distilling flask on the water bath to remove most of the chloroform, which is saved for later runs (Note 1). The residual liquid is shaken vigorously with a solution of 5 g. of potassium iodide in 10 cc. of water, to remove dissolved mercuric iodide. The heavier layer, which still possesses a reddish color, is transferred without drying to a 200-cc. Claisen flask and distilled under reduced pressure. At first a small amount of chloroform and water distils over, after which the higher-boiling material is collected in a separate receiver. Small amounts of inorganic mercury compounds remain in the flask (Note 2).

The o-iodophenol solidifies upon cooling. The yield of material melting at 32–34° is 70 g. (63 per cent of the theoretical amount). The product obtained in this way is slightly yellow. If a purer product is desired, it may be redistilled under reduced pressure. Most of the crude material will distil over a 5° range (b.p. 130°/18 mm. and 186°/160 mm., m.p. 43°).