Checked by R. S. Schreiber and H. E. Cupery.
1. Procedure
A
5-l. three-necked flask is equipped with a
high-speed, motor-driven stirrer passing through a bushing in the center neck (Note
1). The side necks are equipped with
rubber stoppers each carrying a short length of 8-mm. glass tubing, bent at right angles. A 10–12 in. length of stout, flexible
iron wire is passed through one of these pieces of tubing.
Two liters of liquid ammonia (Note
2) and
2 g. of ferric nitrate hydrate are placed in the flask.
One hundred grams of sodium (4.35 g. atoms) is cut into rectangular pieces about 3 by

by

in. in size. One of the pieces of
sodium is hooked onto the lower end of the
iron wire and lowered into the liquid
ammonia. Stirring is not necessary during this part of the reaction, but it is advisable. When the lump of
sodium has reacted, the solution turns from blue to gray, and the remaining pieces of
sodium are added in the same manner. The addition requires about 45 minutes (Note
3).
The stopper carrying the
iron wire is removed, 2 g. of anil is added, and then
528 g. (2 moles) of finely powdered, dry styrene dibromide is added gradually with vigorous stirring. The addition requires about 1 hour (Note
4). Stirring is continued for 2 hours (Note
5) after the addition has been completed, after which
600 ml. of concentrated ammonium hydroxide is added, followed by 1 l. of distilled water, and the mixture is allowed to stand until the frost on the outside of the flask is entirely melted.
The aqueous solution is then steam-distilled from the same flask (Note
6) until no more oil passes over. This usually requires about 6 hours, and 1.5–2 l. of distillate is collected. The
phenylacetylene in the distillate is separated and washed several times with distilled water to remove
ammonia (Note
7). The washed material is dried over anhydrous
magnesium sulfate and distilled through an
efficient column (Note
8) under reduced pressure. Almost the entire product distils at
73–74°/80 mm. The yield is
93–106 g. (
45–52%);
nD20 1.5465–1.5484.
2. Notes
1. A suitable stirrer has been described earlier.
2
2. Additional liquid
ammonia should be added from time to time. Liquid
ammonia can be handled satisfactorily in fairly large amounts in an open flask, as the frost that quickly forms on the outside of the flask slows down evaporation.
3. This is an excellent method for making
sodium amide for many purposes. If the
sodium amide is to be used in another solvent, the solvent should be added to the liquid
ammonia after the
sodium amide is prepared; the
ammonia is allowed to evaporate, and the last traces of
ammonia are expelled by heating the flask on a
steam bath.
4. The
styrene dibromide must not be added too rapidly, or the heat of reaction may cause rapid boiling of the
ammonia and possible loss of part of the mixture.
5. In one run an increase of this stirring period to 2.8 hours resulted in an
11% increase in yield.
6. Because the large amount of
ammonia that comes over may entrain considerable
phenylacetylene, a very efficient cooling system
3 is essential.
7. If acid is used to remove the
ammonia, the product is likely to be dark colored.
8. The checkers used an
18-in. column packed with Berl saddles.
3. Discussion
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