Org. Synth. 1953, 33, 68
DOI: 10.15227/orgsyn.033.0068
4-PENTYN-1-OL
Submitted by E. R. H. Jones, Geoffrey Eglinton, and M. C. Whiting
1.
Checked by Arthur C. Cope and Ronald M. Pike.
1. Procedure
Caution! This preparation should be conducted in a hood to avoid exposure to ammonia.
A solution of
sodium amide in liquid ammonia is prepared according to a procedure previously described
(Note 1) in a
3-l. three-necked round-bottomed flask equipped with a
cold-finger condenser (cooled with Dry Ice) attached through a
soda-lime tower to a gas-absorption trap,
2 a
mercury-sealed stirrer, and an
inlet tube. Anhydrous
liquid ammonia (1 l.) is introduced from a commercial cylinder through the inlet tube, and
1 g. of hydrated ferric nitrate is added, followed by
80.5 g. (3.5 g. atoms) of clean, freshly cut sodium (Note 1) and
(Note 2). The inlet tube is replaced with a
250-ml. dropping funnel, and the mixture is stirred until all the
sodium is converted into
sodium amide, after which
120.5 g. (1 mole) of tetrahydrofurfuryl chloride3 (Note 3) is added over a period of 25 to 30 minutes. The mixture is stirred for an additional period of 1 hour, after which
177 g. (3.3 moles) of solid ammonium chloride is added in portions at a rate that permits control of the exothermic reaction. The flask is allowed to stand overnight in the hood while the
ammonia evaporates. The residue is extracted thoroughly with ten
250-ml. portions of ether, which are decanted through a
Büchner funnel (Note 4). The
ether is distilled, and the residue is fractionated at a reflux ratio of about 5 to 1, through a
column containing a 20-cm. section packed with glass helices yielding
63–71 g. (
75–85%) of
4-pentyn-1-ol, b.p.
70–71° /29 mm.,
nD25 1.4443
(Note 5).
2. Notes
1.
Procedures for converting
sodium to
sodium amide are given on
p. 763 and in a previous volume.
42.
More liquid
ammonia should be added through the inlet tube if vaporization reduces the liquid volume to less than 750 ml.
3.
Freshly distilled
tetrahydrofurfuryl alcohol should be used in the preparation of
tetrahydrofurfuryl chloride according to the procedure of
Organic Syntheses.34.
Ether extraction of the solid must be thorough or the yield will be reduced. A
large Soxhlet extractor may be used if desired.
5.
Others have reported b.p.
154–155°,
nD19 1.4432;
5 b.p.
154–155°,
nD22.5 1.4450.
6 A sample purified through the silver derivative had b.p.
77° /37 mm.,
nD15 1.4464. The
α-naphthylurethan of 4-pentyn-1-ol crystallized as needles from 60–80°
petroleum ether; m.p.
79–80°.
3. Discussion
4-Pentyn-1-ol has been prepared from
4-penten-1-ol3 by bromination followed by dehydrobromination with alkali;
6 by the reaction of
3-bromodihydropyran or
3,4-dihydro-2H-pyran with
n-butylsodium,
n-butyllithium, or
n-butylpotassium;
5,7 by the reaction of
dihydropyran or
2-methylenetetrahydrofuran with
n-amylsodium or
n-butyllithium;
7 by the reduction of
ethyl 4-pentynoate with
lithium aluminum hydride;
8 and by the method used in this preparation.
9
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
petroleum ether
α-naphthylurethan of 4-pentyn-1-ol
ammonia (7664-41-7)
ether (60-29-7)
ammonium chloride (12125-02-9)
sodium (13966-32-0)
tetrahydrofurfuryl alcohol (97-99-4)
sodium amide (7782-92-5)
n-butyllithium (109-72-8)
ferric nitrate
lithium aluminum hydride (16853-85-3)
dihydropyran
2-methylenetetrahydrofuran
n-amylsodium
4-Penten-1-ol (821-09-0)
Tetrahydrofurfuryl chloride (3003-84-7)
4-Pentyn-1-ol (5390-04-5)
3-bromodihydropyran
3,4-dihydro-2H-pyran (110-87-2)
ethyl 4-pentynoate (63093-41-4)
n-butylsodium
n-butylpotassium
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