Org. Synth. 1926, 6, 26
DOI: 10.15227/orgsyn.006.0026
3-CYCLOHEXYLPROPINE
[Propyne, 3-cyclohexyl-]
Submitted by R. Lespieau and M. Bourguel.
Checked by Roger Adams and M. M. Brubaker.
1. Procedure
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. (
66 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.
2. Notes
1.
The
sodamide 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, 86.
2.
Any clean, high-boiling petroleum oil may be used. None of it should boil below 250°.
3.
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.
4.
By a similar procedure
1 decine may be made from
2-bromodecene in
68 per cent yield, b.p.
80–82°/22 mm., and
4-phenylbutine from
4-phenyl-2-bromobutene in
60 per cent yield, b.p.
95–99°/17 mm.
3. Discussion
3-Cyclohexylpropine can be prepared by heating
3-cyclohexyl-1-bromopropene with alcoholic
potassium hydroxide1 or by the action of
sodamide on
3-cyclohexyl-2-bromopropene2
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
calcium chloride (10043-52-4)
hydrochloric acid (7647-01-0)
ammonia (7664-41-7)
ether (60-29-7)
sodium hydroxide (1310-73-2)
potassium hydroxide (1310-58-3)
3-Cyclohexyl-2-bromopropene (53608-85-8)
cyclohexylbromopropene
4-phenyl-2-bromobutene
2-bromodecene
3-CYCLOHEXYLPROPINE,
Propyne, 3-cyclohexyl-,
cyclohexylpropine (17715-00-3)
decine (764-93-2)
4-phenylbutine (16520-62-0)
3-cyclohexyl-1-bromopropene
sodamide (7782-92-5)
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