A
2-l. three-necked round-bottomed flask in an
electric heating mantle is fitted with a
mercury-sealed Hershberg stirrer, a
dropping funnel, and an
efficient reflux condenser topped with a
tube containing soda lime and calcium chloride. In this flask are placed
21.3 g. (0.56 mole) of pulverized lithium aluminum hydride (Note
1) and
300 ml. of dry ether. The mixture is heated under reflux until most of the hydride has dissolved. A solution of
157.3 g. (0.92 mole) of ethyl α-(1-pyrrolidyl)propionate (p.466) in
200 ml. of dry ether is then added slowly with vigorous stirring at such a rate that the solvent refluxes gently. When the addition is complete and the initial reaction subsides, the mixture is stirred at the reflux temperature an additional 30 minutes. The excess
lithium aluminum hydride is decomposed by adding
50 ml. of ethyl acetate slowly with stirring. This is followed by
600 ml. of 6N hydrochloric acid, added slowly with vigorous stirring.
The mixture is transferred to a
separatory funnel. The water layer is separated, washed once with
ether, and made strongly alkaline by the addition of
1 l. of 6N sodium hydroxide (Note
2). The mixture is returned to the original 2-l. three-necked flask. An attachment for continuous
ether extraction is placed in one of the side necks,
2 and 6-in. extension columns are placed in the other two necks. The stirrer is fitted through the center column and neck.
Ether is added through the column attached to the side neck until the proper
ether level is attained. A stopper is then placed on this column. The stirrer is run at such a rate that gentle swirling is accomplished without hindering the separation of the
ether layer, and the continuous extraction with
ether is continued until test with pH paper indicates that the
ether coming over contains no more basic material. The
ether solution of the product is thoroughly dried over anhydrous
potassium carbonate (Note
3). The drying agent is removed by filtration, and the solvent by distillation at atmospheric pressure and finally at water-pump pressure. The residue is distilled at reduced pressure through a
short fractionating column; b.p.
95–96°/20 mm. (
109–110°/40 mm.,
80°/11 mm.);
nD20 1.4780;
nD25 1.4758;
d425 0.9733. The yield is
95–106 g. (
80–90%).