B.
N,N-Dimethylcyclohexylmethylamine. In a
3-l. three-necked flask equipped with a reflux condenser and a dropping funnel, both protected by drying tubes, is placed a suspension of
32 g. (0.85 mole) of lithium aluminum hydride (Note
4) in
400 ml. of anhydrous ether (Note
5). The mixture is stirred with a
magnetic stirrer using a 40-mm. Teflon-covered stirring bar. A solution of
133 g. (0.86 mole) of N,N-dimethylcyclohexanecarboxamide in 300 ml. of anhydrous ether (Note
5) is added at such a rate as to maintain gentle reflux. The addition requires about 1 hour. The flask is then placed in an
electric heating mantle, and the mixture is stirred and heated under reflux for 15 hours. The heating mantle is replaced by an ice bath, and the flask is fitted with an
efficient mechanical, sealed stirrer. Water (70 ml.) is added slowly with vigorous stirring. Stirring is continued for 30 minutes after the addition of water is complete. A cold solution of
200 g. of sodium hydroxide in 500 ml. of water is added at once, and the flask is fitted for steam distillation. The mixture is steam-distilled until the distillate is neutral; about 1.5 l. is collected. The distillate is acidified by careful addition, with water cooling, of
95 ml. of concentrated hydrochloric acid. The two layers are separated and the
ether layer washed with
50 ml. of 10% hydrochloric acid. The combined acidic solutions are concentrated until no more distillate comes over at
steam bath temperature and 20 mm. pressure. The residue is dissolved in 200 ml. of water, the solution cooled, and
110 g. of sodium hydroxide pellets is added slowly, with stirring and external cooling with ice. The two layers are separated, and the aqueous phase is extracted with three
100-ml. portions of ether (Note
6). The combined amine layer and
ether extracts are dried over
40 g. of potassium hydroxide pellets for 3 hours. The drying agent is separated by decantation, and the solvent is removed by distillation through a 20-cm. Vigreux column. The residue, on distillation under reduced pressure, yields
106–107 g. (
88%) of
N,N-dimethylcyclohexylmethylamine, b.p.
76°/29 mm.,
n25D 1.4462–1.4463.