A solution of
134 g. (0.81 mole) of chloral hydrate (Note 1) in 400 ml. of ether (Note
2) is placed in a
2-l. round-bottomed three-necked flask equipped with a
dropping funnel, a
reflux condenser, and an
efficient mercury-sealed stirrer (Note
3). A solution of
12 g. of potassium cyanide (Note 4) in 220 ml. of concentrated ammonium hydroxide (sp. gr. 0.9) is added through the dropping funnel over the course of 15 minutes at a rate sufficient to cause the
ether to reflux vigorously. Stirring is continued for an additional 20 minutes (Note
5). The layers are separated, and the
ether layer is washed once with 75 ml. of water and once with
75 ml. of 10% aqueous sulfuric acid solution (Note
6). (These washings are retained and used again later.) The aqueous layer from the reaction mixture is extracted with three
75-ml. portions of ether, and each
ether extract is washed successively with the same water and
sulfuric acid solutions used previously. The combined
ether extracts are dried with
40 g. of sodium sulfate, the
ether is removed by distillation, and the residue is recrystallized from
200 ml. of benzene. The solid is removed by filtration with suction and washed with two
25-ml. portions of cold benzene. The yield is
66–76 g. melting at
97.5–99.5° (cor.). Concentration of the filtrate gives
1–5 g. of material with a slightly lower (
96–97° cor.) melting point, making the total yield
67–81 g. (
65–78%).