Organic Syntheses, Coll. Vol. 5, p.769 (1973); Vol. 40, p.68 (1960).
gas is an extreme irritant and can cause serious burns to the eyes, etc. It is necessary to carry out the entire reaction under a well-ventilated hood
In small portions, just sufficient to maintain the blue color, 5.0 g. (0.22 gram atom) of clean, metallic sodium
is added with vigorous stirring. After dissolution is complete (Note 3)
, a solution of 23.4 g. (0.20 mole) of indole (Note 4)
in 50 ml. of anhydrous ether
is added slowly and then, after an additional 10 minutes, a solution of 31.2 g. (0.22 mole) of methyl iodide
in an equal volume of anhydrous ether
is added dropwise. Stirring is continued for a further 15 minutes. The ammonia
is allowed to evaporate (Note 5)
, 100 ml. of water is added, followed by 100 ml. of ether
. The ether
layer is separated, the aqueous phase extracted with an additional 20 ml. of ether
, and the combined ether
extracts washed with three 15 ml.-portions of water (Note 6)
and dried over anhydrous sodium sulfate
. The solvent is removed at atmospheric pressure, and the crude oil (n18.5°D
1.6078) is purified by distillation under reduced pressure. 1-Methylindole
is obtained as a colorless oil, b.p. 133°/26 mm.
1.6082. In several runs the yield is 22.3–24.9 g.
Any sealed mechanical stirrer
may be used. Those of the Hershberg2
type were found particularly efficient during the formation of the sodium amide
It was found most advantageous to run in the liquid ammonia
from the commercial cylinder, laid on the floor with the foot raised slightly, and connected to the gas inlet tube with rubber tubing approximately 1 cm. in diameter. The large excess of liquid ammonia
used obviates the need of a dry iceacetone cooling bath
and permits a reasonably rapid formation of sodium amide
This occurs when the blue color has disappeared. The formation of the light gray sodium amide
is usually complete within 20 minutes and may be observed by washing a portion of the outside of the flask with a little alcohol.
A commercial grade of indole
The checkers removed the ammonia
by distillation (water aspirator
The checkers extracted with two 50-ml. portions of ether
and three 50-ml. portions of water.
This preparation is referenced from:
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