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• 1 Perkin, J. Chem. Soc. 51, 1 (1887); Rupe, Ann. 327, 183 (1903).
2 Carpenter and Perkin, J. Chem. Soc. 75, 930 (1899).
* Kishner, J. Russ. Phys.-Chem. Soc. 37, 507 (1905) [Chem. Zentr. 1905, II, 761].
Cyclobutanecarboxylic acid has been prepared by decarboxylation of the 1,1-dibasic acid,1-4 and by decarboxylation of 1-cyano-l-carboxycyclobutane followed by hydrolysis of the cyano group.2
CYCLOPROPYL CYANIDE (Cyclopropane, cyano-)
2Na + 2NH3 -»2NaNH2 + H2
CH2 / \
CICH2CH2CH2CN ¦! NaNH2 —»CH2—CHCN + NaCl + NH3
Submitted by M. J. Schlatter.
Checked by R. L. Skriner and Chris Best.
The apparatus shown in Fig. 2 is assembled in a good hood. One liter of liquid ammonia and 0.5 g. of hydrated ferric nitrate are placed in the 2-1. three-necked flask A, which is equipped with a stirrer and a special reflux condenser cooled with Dry Ice. This condenser is attached to a soda-lime tower which is connected to a source of compressed air through the T-tube C. Over a period of about forty-five minutes, 92 g. (4 gram atoms) of clean sodium shavings is added to the liquid ammonia, and the mixture is stirred until the blue color disappears (one to two hours).
In the similarly equipped 5-1. three-necked flask Â are placed 1.5 1. of liquid ammonia and 440 g. (4.25 moles) of 7-chlorobu-tyronitrile (Org. Syn. Coll. Vol. 1, 1941, 156). The flasks are connected by means of the 12-mm. glass tube D reaching to the bottom of the sodamide flask A and extending 1 cm. through the rubber stopper in one neck of flask B. Vigorous stirring is maintained in both flasks while the sodamide suspension is slowly forced over into the reaction flask in small portions (CautionI Note 1) by means of air pressure applied through C; the
4 Perkin and Sinclair, J. Chem. Soc. 61, 40 (1892).
rate of addition is controlled by placing the finger over the bypass in the T-tube. At first the reaction is violent and only small amounts of the sodamide solution should be added. The addition is continued at such a rate that the total time required for addition of all the sodamide solution is one to one and one-half hours. The sodamide flask is rinsed with 300 cc. of liquid ammonia and the washings are added to the reaction mixture, after which stirr
ring is continued for two hours. During the second hour, addition of Dry Ice to the reflux condenser is discontinued, and the ammonia is permitted to evaporate slowly. At the end of the two-hour stirring period, the inlet tube is replaced by a dropping funnel and 1 1. of dry ether is slowly added (Note 2). The reaction mixture is quickly filtered through a sintered glass funnel, and the filter cake is washed with two 200-cc. portions of dry ether (Note 3). The ammonia and ether are removed by distillation on a water bath through a packed column (Note 4). The residue is then distilled through the column under the pressure of a water pump (Note 5). The yield of cyclopropyl cyanide boiling at
69-70°/80 mm. (75-76°/95 mm.) is 149-152 g. (52-53 per cent of the theoretical amount based upon 7-chlorobutyronitrile) (Notes 6 and 7). The pressure is then reduced, and the unchanged
7-chlorobutyronitrile is collected at 93-96°/26 mm. It amounts to 52-62 g.
1. The reaction is very vigorous, and addition of the sodamide solutions in large portions must be avoided. The use of stopcocks or pinch clamps to regulate the addition is not recommended.'
2. Very little cyclopropyl cyanide is obtained unless the ether is added before complete evaporation of the ammonia.
3. The mixture may be permitted to stand at this point and the ammonia allowed to evaporate spontaneously under a hood.
4. The Carborundum column described in Org. Syn. 20, 96, is quite satisfactory.
5. It is desirable to interpose a Dry Ice trap between the receiver and the pump in order to prevent loss of the nitrile, and too low a pressure should not be used.
6. The submitter reports that an equivalent number of moles of Y-bromobutyronitrile or a mixture of 7-chloro- and 7-bromo-butyronitrile may be substituted for 7-chlorobutyronitrile. If the bromo compound is used the reaction mixture should be refluxed six hours and it is necessary to filter off the sodium bromide just before the final vacuum distillation.
7. This yield is based upon the 7-chlorobutyronitrile taken. When the recovered 7-chlorobutyronitrile (52-62 g.) is taken into account, the yield of cyclopropyl cyanide is about 60 per cent of the theoretical amount.
3. Methods of Preparation
Cyclopropyl cyanide has been prepared by the repeated distillation of 7-chlorobutyronitrile over powdered potassium hydroxide,1'2,3'4,5 or over a mixture of sodium hydroxide and alumina.®