Note: Descriptions are shown in the official language in which they were submitted.
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A METHOD OF PREPARING CYCLOHEXANECARBOXYLIC ACID
USING [2+4] DIELS-ALDER REACTION
Technical Field
The present invention relates to a method of
preparing cyclohexanecarboxylic acid in which 1,3
butadiene and acrylic acid are subjected to [2,4] Diels
Alder reaction to produce 3-cyclohexene-1-carboxylic acid
which is then hydrogenated with hydrogen in the presence
of a platinum or palladium catalyst.
Background Art
Cyclohexanecarboxylic acid is used as the raw
material for synthetic organic materials, pharmaceutical
agents, and fine chemicals. Cyclohexanecarboxylic acid
derivatives are used as insecticides, tumor inhibitors,
allergy inhibitors, and rheumatism inhibitors. For
example, cyclohexanecarboxylic acid is known to be
prepared by a synthesis process using carboxylation of
cyclohexyl magnesium chloride, or by an industrial process
using hydrogenation of benzoic acid.
Literature regarding [2+4] Diels-Alder reaction of
1,3-butadiene and acrylic acid includes Japanese Patent
Publication Pyoung 5-301885 (1993), Japanese Patent
Publication No. Sho 57-028165 (1982), and WO
86/04602(1986). In these patents, there are described the
preparation of 3-cyclohexene-1-carboxylic acid with [2+4]
Diels-Alder reaction, and the application of such a
compound to other compounds.
Although a method of preparing cyclohexanecarboxylic
acid by hydrogenation of 3-cyclohexene-1-carboxylic acid
is not yet known, the following is known with respect to
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the preparation of cyclohexanecarboxylic acid derivatives
by hydrogenation: For example, in Japanese Patent
Publication No. Pyoung 9-40606(1997) and Japanese Patent
Publication No. Sho 49-026261(1974), there is disclosed a
method of preparing cyclohexanecarboxylic acid substituted
at the 4-position by reducing benzoic acid substituted at
the 4-position in the presence of an alkali and a
hydrogenation catalyst. Moreover, German Patent
Publication No. 2349056 A(1975) discloses a method of
preparing 4-aminomethylcyclohexane by reducing p-
aminomethyl benzoic acid using a ruthenium catalyst and an
alkali.
Disclosure of the Invention
The present invention is a method of preparing
cyclohexanecarboxylic acid in which 1,3-butadiene and
acrylic acid are subjected to [2+4] Diels-Alder reaction
to obtain 3-cyclohexene-1-carboxylic acid which is then
hydrogenated using a Pt or Pd catalyst and hydrogen. The
method according to this invention is advantageous in that
the reaction for preparing cyclohexanecarboxylic acid is
carried out in a relatively simple manner and a side
reaction does not substantially occur.
In [2+4] Diels-Alder reaction of the method according
to this invention, examples of a solvent capable of being
used include an aromatic hydrocarbon solvent, such as
toluene, benzene, and xylene, and an inexpensive and
easily available solvent, such as alcohol, such as ethanol
and methanol, and water, and the like. The [2+4] Diels
Alder reaction solvent is used in the amount of 1000 to
50000 based on the weight of acrylic acid. Moreover, the
temperature for carrying out [2+4] Diels-Alder reaction is
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in the range of room temperature to 200°C. The [2+4]
Diels-Alder reaction of the method according to this
invention produces cyclohexanecarboxylic acid in a yield
of 950 or more.
The higher the reaction temperature, the faster the
reaction rate, but some polymers are generally produced.
As a way to solve such a drawback, the use of 4-tert-
butylcatecol (hereinafter, called "TBC") or hydroquinone
as a polymerization inhibitor during the [2+4] Diels-Alder
reaction results in the inhibition of the production of
polymer.
After [2+4] Diels-Alder reaction, the obtained 3-
cyclohexene-1-carboxylic acid is hydrogenated in the
presence of a Pd or Pt catalyst and hydrogen. This
hydrogenation is carried out at a temperature of room
temperature to 100°C under a hydrogen pressure of 10 psi
to 150 psi, in a solvent selected from the group
consisting of ethanol, methanol, water, toluene, and
xylene. The hydrogenation solvent is used in the amount of
1000 to 5000% based on the volume of 3-cyclohexene-1-
carboxylic acid.
Consequently, unlike the prior methods for the
preparation of cyclohexanecarboxylic acid, the method of
this invention is significant in the preparation of fine
chemicals using 1,3-butadiene. In addition, the method of
the invention is advantageous in that the reaction for
preparing cyclohexanecarboxylic acid is carried out in a
relatively simple and easy manner and also the reaction
by-products are conveniently treated.
Best Mode for Carrying Out the Invention
The following examples are for illustration purposes
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only and in no way limit the scope of this invention.
Examples
In the following examples, 3-cyclohexene-1-carboxylic
was synthesized using acrylic acid as dienophile, and 1,3
butadiene as dime. As a solvent for [2+4] Diels-Alder
reaction, an aromatic hydrocarbon compound, such as
toluene, benzene, or xylene, alcohol, or water, was used.
The molar ratio of 1,3-butadiene to dienophile is in the
range of 1 to 1.4. TBC or hydroquinone, as a
polymerization inhibitor, was used in the amount of zero
to 10,000 ppm based on the weight of 1,3-butadiene. After
producing 3-cyclohexene-1-carboxylic acid which is a [2+4]
Diels-Alder reaction product, hydrogenation of 3-
cyclohexene-1-carboxylic acid was carried out using a Pd
or Pt catalyst. The use of each of these catalysts showed
the conversion of 1000.
Meanwhile, [2+4] Diels-Alder reaction was carried out
in a pressure reactor, and hydrogenation was carried out
in a hydrogen reactor or a pressure reactor. The analysis
of the reaction product was performed by the Nuclear
Magnetic Resonance(NMR) spectrum and the Gas
Chromatography-Mass Spectroscopy Detector (GC-MSD) to
confirm the product. When confirming the quantitative
analysis value of the reaction product by gas
chromatography, the analysis was carried out in accordance
with the following conditions:
Capillary column: HP-20, 25mm X 0.20mm X 0.2~m.
Carrier gas: nitrogen
Head pressure: 18 psig
Oven: 80°C(Omin.) to 190°C, (3=10°C/min.
Detector and temperature: FID(280°C).
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Split ratio: 40:1
Make up gas flow rate: 38m1.
Moreover, the ratio of the components was used in terms of
the area ratio of gas chromatography.
Example 1
Into a 1 liter pressure reactor were charged acrylic
acid (72g, 1 mol), xylene 2888 and TBC 75mg. Then; while
stirring the contents of the reactor, 1,3-butadiene 75g
was introduced into the reactor. After that, a temperature
of the resultant mixture was elevated to 120 °C and left
to react at this temperature for 3 hours. Thereafter, the
analysis of the reaction product by NMR spectrometry and
gas chromatography confirmed that 3-cyclohexen-1-
carboxylic acid was obtained in a yield of 990.
Example 2
The procedure of Example 1 was repeated five times
with a reaction temperature and a molar ratio varying for
each time as described in Table 1 below. For each time, 3
cyclohexene-1-carboxylic acid was obtained in a yield
described in Table 1.
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Table 1
Effect of the varying reaction temperatures and molar
ratios of reactants on a yield of 3-cyclohexene-1
carboxylic acid
1,3- Temperature (°C) Reaction Time Yield (o
BD(g)/AA(g)' (hr)
65/72 90 12 89
65/72 1009 93
75/72 1203 99
1 0 72/73 1401.5 99
77/74 2001 99
*1,3-BD: 1,3-butadiene, AA:acrylic acid
Example 3
Into a 1 liter pressure reactor were charged
acrylic acid (72g, 1 mol) and toluene 2888. Then, 1,3-
butadiene 75g was introduced into the reactor. After
that, a temperature of the resultant mixture was
elevated to 120 °C and left to react at this temperature
for 6 hours. Thereafter, the analysis of the reaction
product by NMR spectrometry and gas chromatography
confirmed that 3-cyclohexene-1-carboxylic acid was
obtained in a yield of 980.
Example 4
The procedure of Example 3 was repeated four times
with a reaction solvent and a reaction temperature
varying for each time as described in Table 2 below: For
each time, 3-cyclohexene-1-carboxylic acid was obtained
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in a yield described in Table 2.
Table 2
Effect of the varying kinds of solvents and reaction
temperatures on a yield of 3-cyclohexene-1-carboxylic
acid
Solvent Yield(o) Reaction Time Reaction
(hr) Temperature (°C)
Xylene 99 4.5 120
Toluene 98 6 120
Ethanol 66 8 100
Water 98 8 100
None 99 7 100
Example 5
The procedure was repeated four times with a reaction
temperature varying for each time as described in Table 3.
For each time, 3-cyclohexene-1-carboxylic acid was
obtained in a yield described in Table 3.
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Table3
Effect of the, varying reaction temperatures on a yield
of 3-cyclohexene-1-carboxylic acid
Reaction Temperature Yield (%) Reaction Time
( ~C) (hr)
100 85 6
120 98 6
150 100 6
180 100 3
Example 6
The reaction was carried out for 3 hours under the
same conditions as those in Example 3 except that
anhydrous aluminum trichloride (A1C13) as a catalyst was
further used. 3-Cyclohexene-1-carboxylic acid was obtained
in a yield of 940.
Example 7
3-Cyclohexene-1-carboxylic acid 53g prepared in
Example 1 was dissolved in xylene 1258. The resultant
mixture was hydrogenated at room temperature in the
presence of a 5oPd/C catalyst (3 wto) under a hydrogen
pressure of 85 psi. Cyclohexanecarboxylic acid was
obtained in a yield of 95o at one hour after starting
hydrogenation and in a yield of 99o at 2 hours after
starting hydrogenation.
Example 8
The procedure of Example 7 was repeated four times
with the amount of catalyst varying for each time as
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described in Table 4 below. For each time,
cyclohexanecarboxylic acid was obtained in a yield
described in Table 4.
Table 4
Effect of the varying amounts catalyst on a yield
of of
cyclohexanecarboxylic
acid
Amount of Amount of Amount of Reaction Yield
reactant' solvent catalyst time(hr) (%)
53 125 1.6(3wt%) 1 95
58 140 1.2(2wt%) 2 95
45 105 0.5(lwt%) 3 92
43 100 0.2(0.5wt%)6 72
tteactant:~-cyclonexene-1-carboxylic acid
Example 9
3-Cyclohexene-1-carboxylic acid lOg prepared in
Example 3 was dissolved in toluene 0.5 liter. Then, the
resultant mixture was hydrogenated in the presence of 0.2
g of a 5%Pd/C catalyst (3 wto) under a hydrogen pressure
of 10 psi. Cyclohexanecarboxylic acid was obtained in a
yield of 970.
Example 10
The procedure of Example 9 was repeated three times
with a hydrogen pressure varying for each time as
described in Table 5 below. For each time,
cyclohexanecarboxylic acid was obtained in a yield
described in Table 5:
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Table 5
Effect of the. varying hydrogen pressures on a yield of
cyclohexanecarboxylic acid
Hydrogen pressure (psi) Yield (%)
10 97
20 100
50 100
Example 11
The procedure of Example 9 was repeated three times
with the ratio of reactant to solvent varying for each
time as described in Table 6 below. For each time,
cyclohexanecarboxylic acid was obtained in a yield
described in Table 6.
Table 6
Effect of the varying ratios of reactant to solvent on a
yield of cyclohexanecarboxylic acid
Reactant/Solvent Yield (~)
1/4 100
1/9 97
1/50 97
Example 12
The procedure of Example 9 was repeated three times
with the amount of catalyst varying for each time as
described in Table 7 below. For each time,
cyclohexanecarboxylic acid was obtained in a yield
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described in Table 7.
Table 7
Effect of the varying amounts of catalyst on a yield of
cyclohexanecarboxylic acid
Amount of catalyst Yield (o)
0.1 80
0.2 97
0.5 100
Example 13
The procedure of Example 9 was repeated except that
3o Pd/C catalyst was used instead of 5o Pd/C catalyst.
Cyclohexanecarboxylic acid was obtained in a yield of
100%.
Example 14
The procedure of Example 9 was repeated except that
ethanol was used instead of toluene. Cyclohexanecarboxylic
acid was obtained in a yield of 1000.
Industrial Applicability
The method of this invention produces
cyclohexanecarboxylic acid by subjecting 1,3-butadiene and
acrylic acid to [2+4] Diels-Alder reaction to produce 3-
cyclohexene-1-carboxylic acid, and then hydrogenating the
obtained 3-cyclohexene-1-carboxylic acid. Thus, the method
of this invention is advantageous in that the reaction is
carried out in a relatively simple manner, and also a side
reaction does not occur.
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In the method of this invention, [2+4] Diels-Alder
reaction of 1,3-butadiene and acrylic acid is carried out
using an aromatic hydrocarbon solvent, such as toluene,
benzene, or xylene, at a temperature of room temperature
to 200 °C. In addition, hydrogenation of 3-cyclohexene-1-
carboxylic acid is carried out using an inexpensive and
easily available solvent, such as alcohol, such as ethanol
or methanol, or water, and the like, under very low
pressure, such as a hydrogen pressure of 10 psi to 150
psi, and the reaction yield is 95% or more. Consequently,
this invention is advantageous in that it enables the
production of fine chemicals using 1,3-butadiene, unlike
the prior methods for the preparation of
cyclohexanecarboxylic acid. Moreover, other advantages of
this invention are that the reaction is carried out in a
relatively simple and easy manner, and also the reaction
by-products are conveniently treated after the reaction.
Although the preferred embodiments of the invention
have been disclosed for illustrative purposes, those
skilled in the art will appreciate that various
modifications, additions and substitutions are possible,
without departing from the scope and spirit of the
invention as disclosed in the accompanying claims.
