Organic Syntheses, Coll. Vol. 1, p.191 (1941); Vol. 6, p.26 (1926).
A mixture of 120 g. (3.1 moles) of sodamide (Note 1)
and 200 cc. of purified mineral oil (Note 2)
is ground together in a mortar until the amide is finely pulverized (Note 3)
. This suspension is transferred to a 2-l. round-bottomed, three-necked flask
fitted with a reflux condenser
holding a calcium chloride tube
, a 500-cc. separatory funnel
, and an efficient mechanical stirrer
through a mercury seal
. The mortar and pestle
are rinsed with an additional 250 cc. of the oil which is then added to the reaction flask. This is heated in an oil bath
maintained at 160–165°, the stirrer is started, and 203 g. (1 mole) of cyclohexylbromopropene (p. 186)
is dropped in during one and one-half hours. Ammonia
is evolved, and this is allowed to pass through the condenser and is collected in water.
After all the cyclohexylbromopropene
has been run in, heating is continued for about two hours, the mixture is cooled and 500 cc. of ether
is added. This mixture is poured on 1.5 kg. of cracked ice in a 5-l. flask
and then acidified with 280 cc. of concentrated hydrochloric acid
. The ether
layer is separated, dried over calcium chloride
, and transferred to a 1-l. modified Claisen flask (p. 130)
for distillation. The ether is distilled at ordinary pressure and then the cyclohexylpropine
under diminished pressure. The product boiling up to 115°/20 mm.
is collected and fractionated. The cyclohexylpropine
boils at 58–63°/20 mm.
The higher-boiling material is chiefly unchanged cyclohexylbromopropene
which may be used again in a subsequent run. The yield of cyclohexylpropine
is 80 g.
per cent of the theoretical amount not taking into consideration the recovered cyclohexylbromopropene which amounts to about 10 g.) (Note 4)
. The pure compound boils at 61–63°/24 mm.
must be free from sodium hydroxide
and may be conveniently weighed under the 250 cc. of purified mineral oil which is used to rinse out the mortar. Care must be exercised in the use of old sodamide
as it sometimes contains an explosive compound that might cause trouble. The nature of this explosive compound is not definitely known; however, it appears to be associated with the development of a lemon yellow color. Should any part of the sodamide
develop this color it is recommended that the whole be destroyed at once.
Directions for preparing sodamide
are to be found in Org. Syn. 20
Any clean, high-boiling petroleum oil may be used. None of it should boil below 250°.
It is essential that the sodamide
be very finely divided. The state of subdivision of the sodamide
particles seriously affects the yield of product. A mechanical grinder
was used by the original authors, who obtained better yields than those reported here.
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