Org. Synth. 1953, 33, 82
Submitted by Robert Bruce Moffett1
Checked by N. J. Leonard and S. Gelfand.
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.
, 80°/11 mm.
0.9733. The yield is 95–106 g.
The hydride can be pulverized rapidly and safely by breaking the large pieces with a spatula
, followed by careful crushing with a mortar and pestle
. Caution must be observed because the solid may inflame on prolonged grinding or abrasion. The hydride dust is caustic and irritating.
At this point the mixture should be a mobile milky slurry. The submitter suggests that, if the mixture is too thick to extract, more water or base may be added.
Sufficient drying agent should be used so that no aqueous liquid phase appears.
has been prepared by the lithium aluminum hydride
reduction of ethyl α-(1-pyrrolidyl)propionate
Chemical Abstracts Nomenclature (Collective Index Number);
potassium carbonate (584-08-7)
hydrochloric acid (7647-01-0)
ethyl acetate (141-78-6)
sodium hydroxide (1310-73-2)
lithium aluminum hydride (16853-85-3)
1-Pyrrolidineethanol, β-methyl- (53663-19-7)
Ethyl α-(1-pyrrolidyl)propionate (26846-86-6)
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