Org. Synth. 1971, 51, 55
DOI: 10.15227/orgsyn.051.0055
BICYCLO[1.1.0]BUTANE
[Bicyclo[1.1.0]butane]
Submitted by Gary M. Lampman and James C. Aumiller
1.
Checked by R. A. Fenoglio and K. B. Wiberg.
1. Procedure
A
300-ml., three-necked, round-bottomed flask is equipped with a
mechanical stirrer, a
reflux condenser, and a
pressure-equalizing addition funnel. The condenser is connected in series with two
traps, immersed in liquid
nitrogen, with the exit leading to a
drying tube (Note 1). A line for dry
nitrogen that has a
T-tube joined to a
U-tube containing
mercury is connected to the top of the addition funnel
(Note 2). To the flask are added
150 ml. of purified dioxane (Note 3) and
13.6 g. (0.591 g.-atom) of freshly cut sodium (Note 4). The mixture is heated to reflux, and the molten
sodium is broken up with the stirrer. A solution of
20.0 g. (0.118 mole) of 1-bromo-3-chlorocyclobutane (Note 5) in
20 ml. of dioxane (Note 3) is added to the refluxing
dioxane over a 1-hour period; refluxing is maintained for an additional 2 hours
(Note 6) and
(Note 7). The product in the traps is separated from any
dioxane with the vacuum manifold system shown in
Figure 1 (Note 8). The two traps containing the product are cooled in liquid
nitrogen and connected to one of the
stopcocks on the manifold. A gas storage bulb (
Figure 2) is attached to the other stopcock. All the stopcocks are opened, and the system is evacuated. The stopcock to the pump is then closed, and the
liquid nitrogen bath is removed from the traps and used to cool the gas storage bulb. The traps are warmed slightly, and the
bicyclobutane condenses in the storage bulb, leaving the
dioxane behind, yielding
5–6 g. (
78–94%)
(Note 9) of
bicyclobutane.
Figure 1. Vacuum manifold.
Figure 2. Gas storage bulb.
2. Notes
1.
Although the entire gaseous product is caught in the first trap, this trap tends to plug during the reaction. Therefore, the second trap is used as a safety measure to collect the
bicyclobutane as the first trap is thawed to open the system.
2.
It is essential that a U-tube containing
mercury is connected by a T-connector to the
nitrogen inlet. The U-tube monitors the pressure on the system and acts as a safety valve in the event of a plugged trap. A slight positive pressure is maintained.
3.
Reagent grade dioxane (2 l.) was heated to reflux with the
sodium ketyl of benzophenone, prepared from
10 g. of benzophenone and
1 g. of sodium, until a deep blue solution results. If the color is not developed, another portion of
benzophenone and
sodium is added and heating continued until the color persists. The peroxide-free
dioxane was distilled from the flask and used immediately.
4.
The excess
sodium allows the reaction to proceed at a greater rate and decomposes any peroxides remaining in the
dioxane.
6.
The reflux rate and flow of
nitrogen gas must be kept at a minimum to assure that the amount of
dioxane carried over to the traps in liquid
nitrogen is kept as small as possible.
7.
This reflux time is a minimum since decreased yields were observed when the reflux time was shortened. There was no increase in yield when the refluxing time was increased to 4 hours.
8.
The basic apparatus consists of a
large diameter (about 25 mm.) glass tube to which are attached at least two stopcocks, a
closed-end manometer, and a large stopcock, used to isolate the manifold from the
vacuum pump.
9.
The product, which is about
90% bicyclobutane and
10% cyclobutene, is sufficiently pure for most purposes. The purity of the product can be determined by GC analysis at room temperature, using a
275-cm.-long column containing 20% β,β'-oxydipropionitrile on Chromosorb W (45/60). The retention times are 2.7 and 3.8 minutes for
cyclobutene and
bicyclobutane, respectively.
Bicyclobutane (b.p.
8°) can be stored temporarily in the gas storage bulb as a liquid in an
acetone–dry ice bath or for longer periods of time in an ampoule, sealed under vacuum, and stored in a freezer.
3. Discussion
Bicyclobutane has been prepared by intramolecular addition of divalent carbon to an olefinic double bond,
2 irradiation of
butadiene,
3 decomposition of
cyclopropanecarboxaldehyde tosylhydrazone,
4 and deamination of
cyclobutylamine and
cyclopropylcarbinylamine.
5 The present procedure, based upon a published method,
6 gives the highest yield of the known methods and provides a process for making moderate quantities of material.
The procedure provides a good example of a high-yield intramolecular Wurtz reaction. Intermolecular Wurtz reactions normally do not give high yields of coupled products and are accompanied by formation of alkenes and alkanes corresponding to the alkyl halide.
7 In contrast, intramolecular reactions of 1,3-dihalides with metals such as
sodium are important synthetic methods for making cyclopropane derivatives. Examples are the reactions of
sodium with
pentaerythrityl tetrabromide, giving
spiropentane8 and of
sodium-potassium alloy with
1,3-dibromohexamethylcyclobutane, giving
hexamethylbicyclo[1.1.0]butane.
9 If 1,3-dihalides are not used, the yields of cyclic compounds may be considerably reduced. Thus,
1,4-dibromobutane10 and
3-(bromomethyl)cyclobutyl bromide11 give very little
cyclobutane and
bicyclo[1.1.1]pentane, respectively.
Metals other than
sodium may be considered for the reduction in intramolecular Wurtz reactions.
11 One of the most common of these is
zinc under various reaction conditions. Examples of use of this reagent that have resulted in high yields of
cyclopropane and derivatives of
cyclopropane include
cyclopropane from
1,3-dichloropropane,
12 spiropentane from
pentaerythrityl tetrabromide in the presence of a chelating agent,
13 spiro[2.5]octane from
1,1-bis-(bromomethyl)cyclohexane,
14 and 1,1-dialkylcyclopropanes from 1,3-dibromo-2,2-dialkylpropanes.
14 However,
1-bromo-3-chlorocyclobutane yields no
bicyclobutane on reaction with
zinc,
6 even in the presence of a chelating agent.
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
sodium ketyl of benzophenone
nitrogen (7727-37-9)
mercury (7439-97-6)
Benzophenone (119-61-9)
zinc (7440-66-6)
sodium (13966-32-0)
cyclopropane (75-19-4)
1,3-dichloropropane (142-28-9)
dioxane (123-91-1)
butadiene (106-99-0)
Pentaerythrityl tetrabromide (3229-00-3)
sodium-potassium
1,4-dibromobutane (110-52-1)
cyclobutane (287-23-0)
cyclobutene (822-35-5)
1-Bromo-3-chlorocyclobutane (4935-03-9)
Cyclobutylamine (2516-34-9)
cyclopropylcarbinylamine (2516-47-4)
Bicyclo[1.1.0]butane (157-33-5)
bicyclobutane
cyclopropanecarboxaldehyde tosylhydrazone
spiropentane (157-40-4)
1,3-dibromohexamethylcyclobutane
hexamethylbicyclo[1.1.0]butane
3-(bromomethyl)cyclobutyl bromide
bicyclo[1.1.1]pentane
spiro[2.5]octane (185-65-9)
1,1-bis-(bromomethyl)cyclohexane
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved