Org. Synth. 1923, 3, 57
DOI: 10.15227/orgsyn.003.0057
ETHYLENE CYANOHYDRIN
[Hydracrylonitrile]
Submitted by E. C. Kendall and B. McKenzie.
Checked by H. T. Clarke and W. M. Sperry.
1. Procedure
In a 5-l. flask is placed 612 g. (12.5 moles) of finely powdered sodium cyanide (passed through a meat grinder and then sifted through a 20-mesh sieve) (Note 1); the flask is equipped with a thermometer in a well, an efficient stirrer, and a reflux condenser (Note 2). The whole vessel is then set in a water bath into which warm and cold water can be run at will and if necessary rapidly removed.
A mixture of 250 cc. of water and 1 kg. (807 cc., 12.4 moles) of pure ethylene chlorohydrin (b.p. 126–127°) is then added, the stirring is started, and the temperature of the mixture raised to 45° by external application of warm water. At this point the warm water is rapidly removed (Note 3) and the temperature of the contents of the flask carefully held at 45° by jacketing with water at a suitable temperature (33–35°). After the mixture has been held at 45° for one hour it is allowed to warm up to 48° by allowing the temperature of the water bath to rise about 2°. After an hour at 48° the temperature is raised to 50° and held at this point until the reaction is over; it is necessary to raise the temperature of the bath gradually, and the end of the reaction is noted when the bath temperature reaches 50°. A period of four and one-half to five hours is necessary for this last stage.
Cold water is now placed in the water bath, while the stirrer is kept always in motion, and the temperature of the mixture is reduced to 20–22°. The mass is then filtered by suction and the sodium chloride sucked as dry as possible. This is then washed with about 800 cc. of acetone in small quantities, the washings being collected separately, and then transferred to a flask from which the acetone and water are distilled off with the use of a short fractionating column until the temperature of the vapor reaches 90°. The residue in the flask is then cooled and again filtered from a further small quantity of sodium chloride which separates during the distillation, the filtrate being added to the main product (Note 4).
This is then distilled under reduced pressure from an oil bath, and the fraction boiling at 107–109°/12 mm. (116–118°/20 mm.) is collected as pure material. The yield is 700–705 g. (79–80 per cent of the theoretical amount). There is practically no residue beyond a little salt; the foreruns consist of water, a small amount of unchanged ethylene chlorohydrin, and some ethylene cyanohydrin.
2. Notes
1.
The
sodium cyanide should be finely powdered since it never completely enters into solution, and any lumps present would run the risk of becoming coated over with
sodium chloride. For the same reason, the stirring must be vigorous throughout the operation.
2.
Under the correct conditions no appreciable amount of
hydrogen cyanide escapes from the reflux condenser, but it is wise to carry out the reaction under a
hood, or to lead a tube from the top of the condenser into the open air or to a
gas-absorption trap (Fig. 7 on p. 97).
3.
It is most important that the temperature of the reaction mixture be not allowed to rise prematurely, since if it reaches 50° during the early stages the reaction velocity increases so rapidly that the contents are likely to boil out of the flask. For the same reason it appears necessary that a certain ratio between reacting mass and cooled surface be not exceeded. Runs of twice the above size have been carried out in a 5-l. flask without mishap, but temperature control was difficult and these conditions are extremely hazardous. A run of
4 kg. of ethylene chlorohydrin in a
12-l. flask was attempted, but rapidly went out of control.
4.
When the reaction has been carried out exactly as described, the final product before distillation is very nearly colorless; if the temperature has been allowed to rise too high, a brown color is produced and
ammonia is formed, with corresponding decrease in yield.
3. Discussion
Ethylene cyanohydrin can be prepared from
ethylene oxide and anhydrous
hydrogen cyanide;
1 from
ethylene oxide and
calcium cyanide in aqueous solution at 10–20°;
2 and from
ethylene chlorohydrin and
alkali cyanide in the absence of a solvent by heating to 100° in a closed vessel,
3 by boiling the reagents in 50 per cent aqueous-alcoholic solution,
4 by adding a concentrated aqueous solution of
potassium or sodium cyanide to a boiling solution of the chlorohydrin in
absolute alcohol,
5 or in aqueous solution at 45°.
6
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
alkali cyanide
potassium or sodium cyanide
alcohol (64-17-5)
ammonia (7664-41-7)
sodium cyanide (143-33-9)
sodium chloride (7647-14-5)
hydrogen cyanide (74-90-8)
acetone (67-64-1)
Ethylene oxide (75-21-8)
Ethylene cyanohydrin,
Hydracrylonitrile (109-78-4)
ethylene chlorohydrin (107-07-3)
calcium cyanide (592-01-8)
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