In a
1-l. three-necked, round-bottomed flask equipped with a
mechanical stirrer,
reflux condenser, and powder funnel are placed
180 ml. of reagent grade chloroform,
16.0 g. (0.16 mole) of cyclobutanecarboxylic acid (Note
1), and
48 ml. of concentrated sulfuric acid. The flask is heated in an
oil bath to 45–50°, and
20.0 g. (0.31 mole) of sodium azide (Note
2) is added over a period of 1.5 hours (Note
3). After the addition of
sodium azide is complete, the reaction mixture is heated at 50° for 1.5 hours. The flask is cooled in an
ice bath, and approximately 200 g. of crushed ice is added slowly. A solution of
100 g. of sodium hydroxide in 200 ml. of water is prepared, cooled to room temperature, and then added slowly to the reaction mixture until the pH of the mixture is approximately 12–13. The mixture is poured into a
2-l. three-necked, round-bottomed flask, the flask is set up for steam distillation, and about 2 l. of distillate is collected in a cooled receiver containing
90 ml. of 3N hydrochloric acid (Note
4). The water and
chloroform are removed by distillation under reduced pressure (Note
5), and the
amine hydrochloride is transferred to a
50 ml. round-bottomed flask with a few milliliters of water. A straight condenser is connected to the flask, and the flask is cooled in an ice bath. A slush is prepared by grinding
potassium hydroxide pellets in a
mortar and then adding a minimum volume of water. The slush is added in portions through the top of the condenser. After the mixture has become sufficiently basic, the amine appears as a separate phase. More
potassium hydroxide pellets are added to dry the amine phase. The condenser is replaced by a heated,
vacuum-jacketed Vigreux column equipped with a
soda-lime tube, and the fraction having a boiling point of 79–83° is collected. The distillate is dried over
potassium hydroxide pellets for 2 days. The liquid is decanted into a distilling flask containing a few
potassium hydroxide pellets and distilled through the apparatus described above to give
7–9 g. (
60–80%) of
cyclobutylamine, b.p.
80.5–81.5°,
n25D 1.4356 (Note
6), (Note
7).