Submitted by G. H. Coleman and H. F. Johnstone.
Checked by C. S. Marvel and A. B. Adams.
1. Procedure
To a solution of
25 g. of mercuric chloride in 500 cc. of water in a
5-l. flask, 800 g. of cracked ice is added. A cold solution of
190 g. of sodium hydroxide in 500 cc. of water is added, and a rapid stream of
chlorine is passed into the mixture, which must be kept below 5°. The addition of
chlorine is continued in this way until the yellow precipitate of
mercuric oxide just disappears. Then
1600 cc. of cold nitric acid (1.5
N) is added slowly, with stirring.
The concentration of the
hypochlorous acid solution is determined by adding a measured volume to an excess of
potassium iodide solution acidified with
hydrochloric acid, and titrating with standard
thiosulfate solution. Usually the concentration is found to be between 3.5 and 4 per cent. The amount necessary to react with
123 g. (1.5 moles) of cyclohexene is calculated.
In a
5-l. round-bottomed flask equipped with a good
mechanical stirrer (Note
1) is placed
123 g. (1.5 moles) of cyclohexene (p. 183), and to it is added about one-fourth the calculated amount of the
hypochlorous acid solution. The mixture is kept between 15° and 20°, and stirred vigorously until a 1-cc. test portion gives no yellow color when it is treated with
potassium iodide solution and dilute
hydrochloric acid. When the first portion of the
hypochlorous acid has reacted, a second is added and the process is repeated. When all the
hypochlorous acid has been added and the reaction is complete, the oily layer should be on the bottom and a very slight excess of
hypochlorous acid should be present, as indicated by the
potassium iodide test. If these conditions are not fulfilled,
100-cc. portions of the hypochlorous acid solution are added until the reaction is shown to be complete.
The solution is now saturated with salt and distilled with steam (Note
2). About 2 l. of distillate is required before all of the
2-chlorocyclohexanol passes over. The distillate is saturated with salt and the oily layer separated. The aqueous layer is extracted once with about
250 cc. of ether. This is added to the main portion, which is dried with anhydrous
sodium sulfate. The
ether is removed by distillation and the product distilled under reduced pressure. The fraction boiling at
88–90°/20 mm. (
104–106°/45 mm.) is collected. The yield is
142–148 g. (
70–73 per cent of the theoretical amount).
2. Notes
1. If a mechanical stirrer is not available, shaking the flask by hand will give as good results.
2. In the separation of the product from the
hypochlorous acid solution, steam distillation seems to be desirable. In several runs in which this was not carried out, a larger amount of a dark-colored high-boiling residue remained in the flask after distillation, and the yield of
2-chlorocyclohexanol was smaller.
3. Discussion
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