One hundred and forty milliliters of 30% hydrogen peroxide (1.4 moles) (Note
1) is added to
600 ml. of 88% formic acid (13.7 moles) (Note
2) in a
1-l. three-necked flask equipped with a
thermometer and a
motor-driven stirrer. Freshly distilled
cyclohexene (82 g., 1.0 mole) (Note
3) is added slowly from a
dropping funnel over a period of 20–30 minutes while the temperature of the reaction mixture is maintained between 40° and 45° by cooling with an
ice bath and by controlling the rate of addition (Note
4). The reaction mixture is kept at 40° for 1 hour after all the
cyclohexene has been added, and then it is allowed to stand overnight at room temperature.
The
formic acid and water are removed by distillation from a
steam bath under reduced pressure. An ice-cold solution of
80 g. of sodium hydroxide in 150 ml. of water is added in small portions to the residual viscous mixture of the diol and its formates, with care that the temperature of the mixture does not exceed 45°. The alkaline solution is warmed to 45°, and an equal volume
(350 ml.) or more of ethyl acetate is added. After thorough extraction, the lower layer is separated and extracted at 45° six times with equal volumes of
ethyl acetate. The seven
ethyl acetate solutions (Note
5) are combined (total volume about 2.1 l.), and the solvent is distilled from a steam bath until the residual volume is 300–350 ml. and the solid product begins to crystallize. The mixture is cooled to 0°, and the product is separated by filtration (
77–90 g., melting in the range of
90–98°). The mother liquor is concentrated on a steam bath to a volume of 65–75 ml., and more solid crystallizes. The mixture is cooled and filtered as before and yields an additional
4–15 g. of crude product melting in the range of
80–89°.
trans-1,2-Cyclohexanediol, b.p.
120–125°/4 mm., is obtained by distillation of the combined crude products, with the use of an
oil bath and a flask having a side arm and an air condenser sufficiently wide that they will not become plugged as the product solidifies (Note
6). The yield of product of m.p.
101.5–103° is
75–85 g. (
65–73%) (Note
7).