DESCRIPTION
TITLE OF INVENTION:
METHOD FOR PRODUCING CYCLOBUTANE TETRACARBOXYLIC ACID
DERIVATIVE
5
TECHNICAL FIELD
The present invention relates to a novel method for producing a cyclobutane
tetracarboxylic acid derivative useful as a raw material for e.g. a polyimide.
10 BACKGROUND ART
A cyclobutane tetracarboxylic acid derivative is a compound useful as a raw
material for e.g. a polyimide. As a method for producing the compound, a
photodimerization reaction of a maleic anhydride derivative is known (Patent
Documents 1 to 5).
15 Among them, Patent Document 1 discloses, as a method for producing 1,2,3,4-
cyclobutane tetracarboxylic acid-1,2:3,4-dianhydride (CBDA), a photodimerization
reaction of maleic anhydride in a solvent having a carbonyl group, such as a ketone.
However, it also discloses that the use of e.g. acetophenone, benzophenone or
anthraquinone as a conventional photosensitizer is not effective for this reaction, and
20 the absence of such a photosensitizer is rather preferred for this reaction (the last line in
the lower right column on page (2) to the fourth line in the upper left column on page (3)
of Patent Document 1).
The method for producing a 1,2,3,4-cyclobutane tetracarboxylic acid-1,2:3,4-
dianhydride (CBDA) by a photodimerization reaction of maleic anhydride, disclosed in
25 Patent Document 1, is useful in that maleic anhydride as a raw material is available at a
relatively low cost and that this production method is simple, but this method is
insufficient in photoreaction efficiency and thus has a problem in yield of a desired
product.
PRIOR ART DOCUMENTS
30 PATENT DOCUMENTS
Patent Document 1: JP-A-59-212495
Patent Document 2: JP-A-4-106127
2
Patent Document 3: JP-A-2003-192685
Patent Document 4: JP-A-2006-347931
Patent Document 5: JP-A-2008-69081
DISCLOSURE OF INVENT5 ION
TECHNICAL PROBLEM
The object of the present invention is to provide a method for producing a desired
1,2,3,4-cyclobutane tetracarboxylic acid-1,2:3,4-dianhydride derivative in a high yield
and at a high photoreaction efficiency, by subjecting a specific maleic anhydride
10 derivative to a photodimerization reaction.
SOLUTION TO PROBLEM
The present inventors have conducted extensive studies to solve the above
problems and found that, on the contrary to the disclosure of Patent Document 1, it is
15 possible to improve a photoreaction efficiency of a maleic anhydride compound by the
presence of a compound having acetophenone, benzophenone or benzaldehyde
substituted with an electron-withdrawing group in a reaction system, and as a result it is
possible to produce a desired 1,2,3,4-cyclobutane tetracarboxylic acid-1,2:3,4-
dianhydride derivative in a high yield. The present invention has been accomplished
20 on the basis of these discoveries.
The present invention provides the following.
1. A method for producing a 1,2,3,4-cyclobutane tetracarboxylic acid-1,2:3,4-
dianhydride derivative represented by the formula (2), comprising:
subjecting a maleic anhydride compound represented by the following formula (1)
25 to a photodimerization reaction, in the presence of benzophenone substituted with an
electron-withdrawing group, acetophenone substituted with an electron-withdrawing
group or benzaldehyde substituted with an electron-withdrawing group.
3
wherein R is a hydrogen atom or a C1-20 alkyl group.
2. The method according to the above 1, wherein R is a methyl group.
3. The method according to the above 1, wherein R is a hydrogen atom.
4. The method according to any one of the above 1 to 3, wherein the electronwithdrawing
group is at least one member selected from the group consisting of a fluor5 o
group, a chloro group, a bromo group, an iodo group, a nitro group, a cyano group and
a trifluoromethyl group.
5. The method according to any one of the above 1 to 4, wherein the number of
electron-withdrawing groups is from 1 to 5.
10 6. The method according to any one of the above 1 to 5, wherein the proportion of
benzophenone substituted with an electron-withdrawing group, acetophenone
substituted with an electron-withdrawing group or benzaldehyde substituted with an
electron-withdrawing group to the maleic anhydride compound, is from 0.1 to 20 mol%.
7. The method according to any one of the above 1 to 6, wherein the
15 photodimerization reaction is carried out in a reaction solvent.
8. The method according to the above 7, wherein the reaction solvent is an ester
or an anhydride of an organic carboxylic acid, or a carbonic acid ester.
9. The method according to the above 7 or 8, wherein the reaction solvent is ethyl
acetate or dimethyl carbonate.
20 10. The method according to any one of the above 7 to 9, wherein the reaction
solvent is used in an amount of from 3 to 300 times by mass to the maleic anhydride
compound.
11. The method according to any one of the above 7 to 9, wherein the amount of
the reaction solvent to be used is from 3 to 10 times by mass to the maleic anhydride
25 compound.
12. The method according to any one of the above 1 to 11, wherein the reaction
4
temperature is from 0 to 20 C.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to produce a 1,2,3,4-
cyclobutanetetracarboxylic acid-1,2:3,4-dianhydride derivate as a desired product, 5 uct, at a
high photoreaction efficiency and in a high yield, by subjecting an inexpensive maleic
anhydride compound as a raw material to a photodimerization reaction at a
photoreaction efficiency.
10 BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 illustrates a molecular model arranged on the basis of X-ray structural
analysis of a 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid-1,2:3,4-dianhydride
(hereinafter also referred to as 1,3-DM-CBDA) single crystal obtained in Reference
Example 1.
15 Fig. 2 is a molecular model arranged on the basis of X-ray structural analysis of a
1,3-DM-CBDA single crystal obtained in Example 20 of the present invention.
DESCRIPTION OF EMBODIMENTS
The method for producing a 1,2,3,4-cyclobutanetetracarboxylic acid-1,2:3,4-
20 dianhydride derivative represented by the formula (2), by subjecting a maleic anhydride
compound represented by the formula (1) to a photodimerization reaction, is
represented by the following reaction scheme.
wherein R is a hydrogen atom or a C1-20, preferably C1-12, particularly preferably C1-6
25 alkyl group.
The C1-20 alkyl group may be a linear or branched saturated alkyl group, or a linear
or branched unsaturated alkyl group. As a specific example, methyl, ethyl, n-propyl, ipropyl,
n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, 1-methyl-n-butyl, 2-methyl-n-butyl, 3-
5
methyl-n-butyl, 1,1-dimethyl-n-propyl, n-hexyl, 1-methyl-n-pentyl, 2-methyl-n-pentyl,
1,1,-dimethyl-n-butyl, 1-ethyl-n-butyl, 1,1,2-trimethyl-n-propyl, n-heptyl, n-octyl, n-nonyl,
n-decyl, n-dodecyl, n-eicosyl, 1-methylvinyl, 2-allyl, 1-ethylvinyl, 2-methylallyl, 2-butenyl,
2-methyl-2-butenyl, 3-methyl-2-butenyl, 3-methyl-3-butenyl, 2-hexenyl, 4-methyl-3-
pentenyl, 4-methyl-4-pentenyl, 2,3-dimethyl-2-butenyl, 1-ethyl-2-pentenyl, 3-dodecenyl5 ,
propargyl, 3-butynyl, 3-methyl-2-propynyl or 9-decynyl may be mentioned.
Here, n represents normal, i represents iso, s represents secondary, and t
represents tertiary, respectively.
The maleic anhydride compound represented by the formula (1) may, for example,
10 be citraconic anhydride, 2-ethyl maleic anhydride, 2-isopropyl maleic anhydride, 2-nbutyl
maleic anhydride, 2-t-butyl maleic anhydride, 2-n-pentyl maleic anhydride, 2-nhexyl
maleic anhydride, 2-n-heptyl maleic anhydride, 2-n-octyl maleic anhydride, 2-nnonyl
maleic anhydride, 2-n-decyl maleic anhydride, 2-n-dodecyl maleic anhydride, 2-neicosyl
maleic anhydride, 2-(1-methyl vinyl) maleic anhydride, 2-(2-allyl) maleic
15 anhydride, 2-(1-ethyl vinyl) maleic anhydride, 2-(2-methyl allyl) maleic anhydride, 2-(2-
butenyl) maleic anhydride, 2-(2-hexenyl) maleic anhydride, 2-(1-ethyl-2-pentenyl) maleic
anhydride, 2-(3-dodecenyl) maleic anhydride, 2-propargyl maleic anhydride, 2-(3-
butynyl) maleic anhydride, 2-(3-methyl-2-propynyl) maleic anhydride or 2-(9-decynyl)
maleic anhydride.
20 Among them, citraconic anhydride, 2-ethyl maleic anhydride, 2-isopropyl maleic
anhydride, 2-n-butyl maleic anhydride, 2-t-butyl maleic anhydride, 2-n-pentyl maleic
anhydride, 2-n-hexyl maleic anhydride, 2-n-heptyl maleic anhydride, 2-n-octyl maleic
anhydride, 2-n-nonyl maleic anhydride, 2-n-decyl maleic anhydride or 2-n-dodecyl
maleic anhydride is preferred, and citraconic anhydride, 2-ethyl maleic anhydride, 2-
25 isopropyl maleic anhydride, 2-n-butyl maleic anhydride, 2-t-butyl maleic anhydride, 2-npentyl
maleic anhydride or 2-n-hexyl maleic anhydride is more preferred, in view of high
photoreaction efficiency.
In the present invention, benzophenone substituted with an electron-withdrawing
group, acetophenone substituted with an electron-withdrawing group or benzaldehyde
30 substituted with an electron-withdrawing group, functions as a sensitizer.
The electron-withdrawing group may be at least one member selected from the
group consisting of a fluoro group, a chloro group, a bromo group, an iodine group, a
6
nitro group, a cyano group and a trifluoromethyl group, preferably a fluoro group, a
chloro group, a bromo group, a cyano group or a trifluoromethyl group, particularly
preferably a fluoro group or a chloro group.
The number of the electron-withdrawing group is from 1 to 10, preferably from 1 to
5, particularly preferably from 1 to 5 3.
The substitution position of the electron-withdrawing group may be ortho position,
meta position or para position, preferably ortho position or para position, particularly
preferably para position, to the carbonyl group.
When the number of the electron-withdrawing group is two or more, the electron10
withdrawing groups may be the same or different. Further, it may be anthraquinone in
which carbonyl groups having an electron-withdrawing effect are crosslinked at each
ortho position.
As a specific example of benzophenone substituted with an electron-withdrawing
group, 2-fluorobenzophenone, 3-fluorobenzophenone, 4-fluorobenzophenone, 2-
15 chlorobenzophenone, 3-chlorobenzophenone, 4-chlorobenzophenone, 2-
cyanobenzophenone, 3-cyanobenzophenone, 4-cyanobenzophenone, 2-
nitrobenzophenone, 3-nitrobenzophenone, 4-nitrobenzophenone, 2,4’-
dichlorobenzophenone, 4,4’-difluorobenzophenone, 4,4’-dichlorobenzophenone, 4,4’-
dibromobenzophenone, 3,3’-bis(trifluoromethyl)benzophenone, 3,4’-
20 dinitrobenzophenone, 3,3’-dinitrobenzophenone, 4,4’-dinitrobenzophenone, 2-chloro-5-
nitrobenzophenone, 1,3-bis(4-fluorobenzoyl)benzene, 1,3-bis(4-chlorobenzoyl)benzene,
2,6-dibenzoylbenzonitrile, 1,3-dibenzoyl-4,6-dinitrobenzene or anthraquinone may be
mentioned. Among them, 4,4’-difluorobenzophenone or 4,4’-dichlorobenzophenone is
preferred.
25 Acetophenone substituted with an electron-withdrawing group may, for example,
be 2’-fluoroacetophenone, 3’-fluoroacetophenone, 4’-fluoroacetophenone, 2’-
chloroacetophenone, 3’-chloroacetophenone, 4’-chloroacetophenone, 2’-
cyanoacetophenone, 3’-cyanoacetophenone, 4’-cyanoacetophenone, 2’-
nitroacetophenone, 3’-nitroacetophenone, 4’-nitroacetophenone, 2’,4’-
30 difluoroacetophenone, 3’,4’-difluoroacetophenone, 2’,4’-dichloroacetophenone, 3’,4’-
dichloroacetophenone, 4’-chloro-3’-nitroacetophenone, 4’-bromo-3’-nitroacetophenone
or 4’-fluoro-3’-nitroacetophenone. Among them, 4’-fluoroacetophenone, 4’-
7
chloroacetophenone, 2’,4’-difluoroacetophenone, 3’,4’-difluoroacetophenone, 2’,4’-
dichloroacetophenone or 3’,4’-dichloroacetophenone is preferred.
Benzaldehyde substituted with an electron-withdrawing group may, for example,
be 2-fluorobenzaldehyde, 3-fluorobenzaldehyde, 4-fluorobenzaldehyde, 2-
chlorobenzaldehyde, 3-chlorobenzaldehyde, 4-chlorobenzaldehyde, 5 2-
cyanobenzaldehyde, 3-cyanobenzaldehyde, 4-cyanobenzaldehyde, 2-
nitrobenzaldehyde, 3-nitrobenzaldehyde, 4-nitrobenzaldehyde, 2,4-
difluorobenzaldehyde, 3,4-difluorobenzaldehyde, 2,4-dichlorobenzaldehyde, 3,4-
dichlorobenzaldehyde, 2-chloro-5-nitrobenzaldehyde, 4-chloro-2-nitrobenzaldehyde, 4-
10 chloro-3-nitrobenzaldehyde, 5-chloro-2-nitrobenzaldehyde, 2-fluoro-5-
nitrobenzaldehyde, 4-fluoro-3-nitrobenzaldehyde or 5-fluoro-2-nitrobenzaldehyde.
Among them, 4-fluorobenzaldehyde, 4-chlorobenzaldehyde, 2,4-difluorobenzaldehyde,
3,4-difluorobenzaldehyde, 2,4-dichlorobenzaldehyde or 3,4-dichlorobenzaldehyde is
preferred.
15 The amount of the sensitizer to be used is not particularly limited so long as it is
possible to accelerate a photoreaction rate, but it is preferably from 0.1 to 20 mol%,
more preferably from 0.1 to 5 mol% to the maleic anhydride compound. The sensitizer
is preferably used alone in view of easiness of treatment after the reaction.
As a reaction solvent, an organic solvent commonly used for a photochemical
20 reaction may be used. However, in the case of an industrially applicable solvent, it is
necessary to meet requirements (1) to be a carbonyl compound having a high
photosensitization effect, (2) to have a high solubility of the maleic anhydride compound
as a raw material, and to have a low solubility of the CBDA derivative compound
produced so as to suppress a decomposition reaction of the CBDA derivative
25 compound, (3) to have a high solubility of a by-product so that a CBDA derivative
compound can be purified only by washing with the same solvent, (4) to be a compound
having no low-boiling point as to increase the risk of flammability and further having a
boiling point of around 100°C so as not to leave the compound in a CBDA derivative
compound, (5) to be environmentally safe, (6) to be stable during photoreaction, and (7)
30 to be available at a low cost. In order to meet these requirements, an ester or an
anhydride of an organic carboxylic acid or a carbonic acid ester is preferred as the
reaction solvent. As the reaction solvent, n-hexane, n-heptane, cyclohexane,
8
acetonitrile, acetone, dichloromethane, chloroform or tetrahydrofuran may, for example,
be also used.
As the ester of an organic carboxylic acid, it is suitably a fatty acid alkyl ester
represented by the formula: R1COOR2 (wherein R1 is hydrogen, or preferably a C1-4
alkyl group, more preferably a C1-2 alkyl group, and R2 is a C1-4 alkyl group, mor5 e
preferably a C1-3 alkyl group.)
A preferred example of the ester of an organic carboxylic acid may be methyl
formate, ethyl formate, n-propyl formate, i-propyl formate, n-butyl formate, i-butyl
formate, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl
10 acetate, i-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, ipropyl
propionate, n-butyl propionate or i-butyl propionate. Further, ethylene glycol
diformate, ethylene glycol diacetate or ethylene glycol dipropionate may, for example,
be used.
Further, the anhydride of an organic carboxylic acid is preferably one represented
15 by the formula: (R1 CO)2 O (wherein R1 is the same as the above including a preferred
embodiment). As a preferred specific example, propionic anhydride, butyric anhydride,
trifluoroacetic anhydride or acetic anhydride may be mentioned. Among them, acetic
anhydride is preferred from the viewpoint that it is possible to obtain 1,3-DACBDA in a
higher yield.
20 The carbonic acid ester may suitably be a carbonic acid dialkyl ester having a C1-3
alkyl group, more preferably a C1-2 alkyl group. As a preferred example, dimethyl
carbonate, diethyl carbonate or a mixture thereof may be mentioned.
In a case where the reaction solvent contains ethyl acetate, dimethyl carbonate,
diethyl carbonate or ethylene glycol diacetate, a CBDA derivative compound produced
25 has a low solubility despite that the maleic anhydride compound as a raw material has a
high solubility, whereby a desired compound is precipitated as a crystal during the
reaction, and therefore it is possible to suppress a reverse reaction from the CBDA
derivative compound to the maleic anhydride compound or a side reaction such as
production of oligomer.
30 The amount of the reaction solvent to be used is from 3 to 300 times by mass,
more preferably from 4 to 250 times by mass to the maleic anhydride compound. The
solvent may be used alone or in combination of two or more, but the solvent is
9
preferably used alone in view of easiness of treatment after the reaction.
Further, the amount of the reaction solvent to be used is preferably low, and in
such a case, the concentration of a maleic anhydride compound becomes high, the
reaction rate becomes high, and the yield of the product obtained becomes large.
Accordingly, in order to increase the reaction rate and the yield of the product, 5 t, the
amount of the solvent to be used is preferably from 3 to 10 times by mass to the maleic
anhydride compound.
In this photoreaction, a wavelength of light is from 200 to 400 nm, more preferably
from 250 to 350 nm, particularly preferably from 280 to 330 nm. As a light source, a
10 low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury
lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, electrodeless lamp or a lightemitting
diode, etc. is preferred since it is possible to obtain a CBDA derivative
compound in a particularly high yield. Among them, a high-pressure mercury lamp, an
ultrahigh-pressure mercury lamp or a light-emitting diode is preferred.
15 Further, with respect to a reaction apparatus, it is preferred to change a light
source-cooling pipe from lime glass to Pyrex (registered trademark) glass, whereby a
colored polymer is less attached to the light source-cooling pipe and impurities are less
produced, and it is thereby possible to improve the yield of a CBDA derivative
compound.
20 If the reaction temperature becomes high, a polymer tends to be produced as a
by-product, and if the reaction temperature becomes low, the solubility of the maleic
anhydride compound tends to be low, whereby the production efficiency will be
deteriorated. Therefore, the reaction temperature is preferably from -20 to 80°C, more
preferably from -10 to 50°C. In particular, when the reaction temperature is from 0 to
25 20°C, the production of a by-product is significantly suppressed, and therefore it is
possible to obtain a CBDA derivative compound in high selectivity and yield.
The reaction time may vary depending upon e.g. the amount of a maleic
anhydride compound to be charged, the type of a light source or the irradiation dose,
but it is possible to carry out the reaction until the proportion of an unreacted maleic
30 anhydride compound becomes preferably from 0 to 40%, more preferably from 0 to
10%.
The reaction time is usually from 1 to 200 hours, preferably from 1 to 100 hours,
10
more preferably from 1 to 60 hours.
Further, the conversion rate may be obtained by analyzing a reaction fluid by e.g.
gas chromatography.
As the reaction time becomes long, the conversion rate of a maleic anhydride
compound increases and the precipitation amount of a CBDA derivative 5 compound
increases, and as a result, the CBDA derivative compound produced tends to attach to
an exterior wall (a reaction fluid side) of a light source-cooling pipe, whereby crystal
coloration or light efficiency (unit power × yield per hour) decrease accompanied by
decomposition reaction tends to be observed. Therefore, it is practically undesirable to
10 take a long time in one batch for increasing the conversion rate of the maleic anhydride
compound since the production efficiency decreases in practice.
Further, the reaction may be carried out by either a batch-type or a flow-type, but
batch-type is preferred. Further, the reaction pressure may be either atmospheric
pressure or elevated pressure, but is preferably atmospheric pressure.
15 The 1,2,3,4-cyclobutane tetracarboxylic acid-1,2:3,4-dianhydride derivative as a
desired compound may be obtainable by carrying out photoreaction, filtrating a
precipitate in a reaction fluid, washing a collected product with an organic solvent,
followed by drying under reduced pressure.
The amount of the organic solvent to be used for washing the collected product, is
20 not limited so long as it is possible to transfer a precipitate remained in a reactor to a
filter. If the amount of the organic solvent is large, the desired compound tends to be
transferred to a filtrate, and the recovery rate thereby decreases. Therefore, the
amount of the organic solvent to be used for washing the collected product, is preferably
from 0.5 to 10 times by mass, more preferably from 1 to 2 times by mass, to the maleic
25 anhydride compound used in the reaction.
The organic solvent to be used for washing the collected product is not particularly
limited, but it is undesirable to use a solvent having high solubility of the product since
the desired compound tends to be transferred to a filtrate, and the recovery rate thereby
decreases. Therefore, a preferred organic solvent to be used for washing the collected
30 product may, for example, be methyl formate, ethyl formate, n-propyl formate, i-propyl
formate, n-butyl formate, i-butyl formate, methyl acetate, ethyl acetate, n-propyl acetate,
i-propyl acetate, n-butyl acetate, i-butyl acetate, methyl propionate, ethyl propionate, n11
propyl propionate, i-propyl propionate, n-butyl propionate, i-butyl propionate, ethylene
glycol diformate, ethylene glycol diacetate, ethylene glycol dipropionate, dimethyl
carbonate or diethyl carbonate, or a solvent which does not solve a product and is not
reactive with the product, such as toluene, hexane, heptane, acetonitrile, acetone,
chloroform or acetic anhydride, or a mixed solvent thereof, as a reaction solvent to 5 be
used for photodimerization reaction. Among them, ethyl acetate, dimethyl carbonate or
acetic anhydride is preferred, and ethyl acetate or dimethyl carbonate is more preferred.
Further, a compound obtained by washing the collected product is further washed
with stirring in an organic solvent at a normal temperature or under heating, and a
10 precipitate is collected, whereby it is possible to improve the purity of the 1,2,3,4-
cyclobutane tetracarboxylic acid-1,2:3,4-dianhydride derivative represented by the
formula (2). In the case of using a high purity product of the 1,2,3,4-cyclobutane
tetracarboxylic acid-1,2:3,4-dianhydride derivative represented by the formula (2), it is
possible to obtain a higher molecular weight and lower dispersed polymer than a
15 polymer produced by using a low purity product, and therefore the high purity 1,2,3,4-
cyclobutane tetracarboxylic acid-1,2:3,4-dianhydride derivative represented by the
formula (2) is preferred with a view to obtaining a higher molecular weight and lower
dispersed polymer.
The organic solvent to be used for the washing is not particularly limited, but it is
20 undesirable to use a solvent having high solubility of the product since the desired
compound tends to be transferred to a filtrate, and the recovery rate thereby decreases.
Therefore, the above-described preferred organic solvent to be used for washing after
the washing of the collected product is mentioned. Among them, ethyl acetate,
dimethyl carbonate, acetonitrile or acetic anhydride is preferred, and acetic anhydride is
25 more preferred since it is possible to ring-closing a hydrolyzate.
EXAMPLES
Now, the present invention will be described in detail with reference to Examples,
but it should be understood that the present invention is by no means restricted thereto.
30 Further, analytical methods employed in Examples are as follows.
(GC analytical conditions>
Apparatus: GC-2010 Plus (manufactured by SHIMADZU Corporation),
12
Column: DB-1 (manufactured by Agilent·Technologies) diameter 0.25 mm ×
length 30 m, film thickness 0.25 um,
Carrier gas: He, detector: FID, sample injection amount: 1 um, inlet port
temperature: 160°C, detector temperature: 220°C, column temperature: 70°C (20 min)-
40°C/min-220°C (15 min), split ratio: 1:50, internal standard substance: butyl lactat5 e.
<1H NMR analytical conditions>
Apparatus: Fourier transform superconducting NMR spectrometer (FT-NMR)
INOVA-400 (manufactured by Varian) 400 MHz,
Solvent: DMSO-d6, internal standard substance: tetramethylsilane (TMS).
10
Apparatus: DSC1 (manufactured by Mettler-Toredo International Inc.),
Temperature: 35°C-5°C/min-400°C, Pan: Au (closed).

Apparatus: APEX2 (manufactured by Bruker),
15 Temperature: 298K, X-ray: Cu.
COMPARATIVE EXAMPLE 1
O
O
O
h
1,3-DM-CBDA
O O
O O
O O
CA 1,2-DM-CBDA
O O
O O
O O
Me2CO3
In a nitrogen atmosphere, into a 30 mL Pyrex (registered trademark) glass test
tube, 0.10 g (0.89 mmol) of a citraconic anhydride (CA), 20 g (222 mmol, 200 times by
20 mass to the citraconic anhydride (CA)) of dimethyl carbonate were charged, and
dissolved with stirring by a magnetic stirrer. Then, the resultant was irradiated with a
100 W high-pressure mercury lamp for 4 hours with stirring at a temperature of from 10
to 15°C. After the irradiation, the reaction fluid was quantitatively analyzed by gas
chromatography, and as a result the remaining ratio of the citraconic anhydride (CA)
25 was 26.2%. Further, 2 g of the reaction fluid in a reaction vessel was taken out, and a
solvent was distilled off under a pressure of from 70 to 80 Torr by an evaporator. A
crude product obtained was analyzed by 1H NMR and confirmed to be a mixture
containing 1,3-DM-CBDA and 1,2-DM-CBDA (1,3-DM-CBDA:1,2-DM-CBDA=48.3:51.7).
1 H NMR ( DMSO-d6, δ ppm ) ( 1,3-DM-CBDA ): 1.38 ( s, 6H ), 3.89 ( s, 2H ).
13
1 H NMR ( DMSO-d6, δ ppm ) ( 1,2-DM-CBDA ): 1.37 ( s, 6H ), 3.72 ( s, 2H ).
COMPARATIVE EXAMPLE 2
O
O
O h
BP
1,3-DM-CBDA
O O
O O
O O
CA 1,2-DM-CBDA
O O
O O
O O
Me2CO3
In a nitrogen atmosphere, into a 30 mL Pyrex (registered trademark) glass test
5 tube, 0.10 g (0.89 mmol) of a citraconic anhydride (CA), 0.020 g (0.11 mmol, 20 mass%
to the citraconic anhydride (CA)) of benzophenone (BP) and 20 g (222 mmol, 200 times
by mass to the citraconic anhydride (CA)) of dimethyl carbonate were charged, and
dissolved with stirring by a magnetic stirrer. Then, the resultant was irradiated with a
100 W high-pressure mercury lamp for 4 hours with stirring at a temperature of from 10
10 to 15°C. After the irradiation, a reaction fluid was quantitatively analyzed by gas
chromatography, and as a result the remaining ratio of the citraconic anhydride (CA)
was 3.9%. Further, 2 g of the reaction fluid in a reaction vessel was taken out, and a
solvent was distilled off under a pressure of from 70 to 80 Torr by an evaporator. A
crude product obtained was analyzed by 1H NMR and confirmed to be a mixture
15 containing 1,3-DM-CBDA and 1,2-DM-CBDA (1,3-DM-CBDA:1,2-DM-CBDA=48.3:51.7).
COMPARATIVE EXAMPLES 3 to 10 and EXAMPLES 1 to 9
A series of operations was carried out in the same manner as in Comparative
Example 2 except that 20 wt% of each sensitizer was added to a citraconic anhydride
(CA). Further, the remaining ratio of a citraconic anhydride (CA) and the production
20 ratio (1,3-DM-CBDA:1,2-DM-CBDA) of 1,3-DM-CBDA to 1,2-DM-CBDA were calculated.
The type of the sensitizer added and the result are shown in the following Table.
Further, the remaining ratio and the reaction rate of the citraconic anhydride in a
reaction fluid obtained herein, and the production ratio of 1,3-DM-CBDA to 1,2-DMCBDA
were calculated, and shown in Table together with the results obtained in
25 Comparative Examples 1 and 2. Here, the reaction rate in Table was calculated from
the number of moles of the citraconic acid used and the remaining ratio of the citraconic
acid at the time when the reaction was carried out for 4 hours. Accordingly, when the
remaining ratio of the citraconic acid was 0, the reaction rate was 0.22, but there is a
possibility that an actual reaction rate is higher than 0.22.
30
14
TABLE 1
Sensitizer (20 wt%)
Citraconic anhydride Production ratio
(1H NMR)
Remaining
ratio of
(GC
quantity)
[%]
Reaction
rate
[mmol/hr]
1,3-
DMCBDA
[mol%]
1,2-
DMCBDA
[mol%]
Comp.
Ex. 1
- 26.2 0.16 48.3 51.7
Comp.
Ex. 2
Benzophenone 3.9 0.21 48.3 51.7
Comp.
Ex. 3
Acetophenone 46.2 0.12 47.6 52.4
Comp.
Ex. 4
Benzaldehyde 21.7 0.17 45.9 54.1
Comp.
Ex. 5
4'-methoxyacetophenone 64.7 0.08 48.8 51.2
Comp.
Ex. 6
4-methoxybenzaldehyde 36.0 0.14 48.5 51.5
Comp.
Ex. 7
4,4'-
bis(dimethylamino)benzophenone
69.6 0.07 50.5 49.5
Comp.
Ex. 8
4,4'-dimethoxybenzophenone 25.6 0.17 47.4 52.6
Comp.
Ex. 9
4-methoxybenzophenone 20.3 0.18 48.8 51.2
Comp.
Ex. 10
Xanthone 58.8 0.09 45.9 54.1
Ex. 1 4'-chloroacetophenone 0.9 0.22 48.1 51.9
Ex. 2 4-chlorobenzaldehyde 0 0.22 42.6 57.4
Ex. 3 3,3'-
bis(trifluoromethyl)benzophenone
0 0.22 49.3 50.7
Ex. 4 4-chlorobenzophenone 0 0.22 45.5 54.5
Ex. 5 4,4'-dichlorobenzophenone 0 0.22 48.3 51.7
Ex. 6 4,4'-difluorobenzophenone 0 0.22 49.5 50.5
Ex. 7 4,4'-dibromobenzophenone 0 0.22 49.0 51.0
Ex. 8 4-cyanobenzophenone 0 0.22 48.8 51.2
Ex. 9 Anthraquinone 1.5 0.22 37.7 62.3
EXAMPLE 10
15
O
O
O h
ClBP
1,3-DM-CBDA
O O
O O
O O
CA 1,2-DM-CBDA
O O
O O
O O
Me2CO3
In a nitrogen atmosphere, into a 300 mL Pyrex (registered trademark) glass fivenecked
flask, 3.5 g (31.2 mmol) of a citraconic anhydride (CA), 0.70 g (3.23 mmol, 10
mol% to the citraconic anhydride (CA)) of 4-chlorobenzophenone (ClBP) and 136.5 g
5 (1,515 mmol, 39.0 wt times to the citraconic anhydride (CA)) of dimethyl carbonate were
charged and dissolved with stirring by a magnetic stirrer.
Then, the resultant was irradiated with a 100 W high-pressure mercury lamp for
one hour with stirring at a temperature of from 10 to 15°C. After the irradiation, a
reaction fluid was quantitatively analyzed by gas chromatography, and as a result the
10 remaining ratio of the citraconic anhydride (CA) was 69.1%. Further, 0.2 g of the
reaction fluid in a reaction vessel was taken out, and a solvent was distilled off under a
pressure of from 70 to 80 Torr by an evaporator. A crude product obtained was
analyzed by 1H NMR and confirmed to be a mixture (1,3-DM-CBDA:1,2-DM-CBDA =
44.6:55.4) containing 1,3-DM-CBDA and 1,2-DM-CBDA.
15 EXAMPLES 11 to 13
A series of operations was carried out in the same manner as in Example 10
except that each type of the sensitizer was used in a proportion shown in the following
Table. Further, the remaining ratio and the reaction rate of the citraconic anhydride in
a reaction fluid obtained herein, and the production ratio of 1,3-DM-CBDA to 1,2-DM20
CBDA, were calculated, and shown in Table together with the result obtained in
Example 10. Here, the reaction rate in Table is calculated from the number of mole of
the citraconic acid used and the remaining ratio of the citraconic acid at the time when
the reaction was carried out for one hour.
16
TABLE 2
Sensitizer (10 wt%)
Citraconic anhydride Production ratio
(1H NMR)
Remaining
ratio of (GC
quantity)
[%]
Reaction
rate
[mmol/hr]
1,3-DMCBDA
[mol%]
1,2-DMCBDA
[mol%]
Ex. 10 4-chlorobenzophenone 69.1 9.33 44.6 55.4
Ex. 11 2,4'-dichlorobenzophenone 55.9 12.66 45.5 54.5
Ex. 12 4,4'-dichlorobenzophenone 47.2 15.51 48.3 51.7
Ex. 13 4,4'-difluorobenzophenone 41.6 16.60 47.4 52.6
COMPARATIVE EXAMPLE 11
In a nitrogen atmosphere, into a 300 mL Pyrex (registered trademark) glass fivenecked
flask, 35.0 g (312 mmol) of a citraconic anhydride (CA) and 152 g (1,682 mmol5 ,
4.33 wt times to the citraconic anhydride (CA)) of dimethyl carbonate were charged, and
dissolved with stirring by a magnetic stirrer. Then, the resultant was irradiated with a
100 W high-pressure mercury lamp for 6 hours with stirring at a temperature of from 10
to 15°C. After the irradiation, a reaction fluid was quantitatively analyzed by gas
10 chromatography, and as a result the remaining ratio of the citraconic anhydride (CA)
was 88.5%. Further, 0.2 g of the reaction fluid in a reaction vessel was taken out, and
a solvent was distilled off under a pressure of from 70 to 80 Torr by an evaporator. A
crude product obtained was analyzed by 1H NMR and confirmed to be a mixture (1,3-
DM-CBDA:1,2-DM-CBDA = 41.7:58.3) containing 1,3-DM-CBDA and 1,2-DM-CBDA.
15 EXAMPLE 14
O
O
O h
DClBP
1,3-DM-CBDA
O O
O O
O O
CA 1,2-DM-CBDA
O O
O O
O O
Me2CO3
In a nitrogen atmosphere, into a 300 mL Pyrex (registered trademark) glass fivenecked
flask, 35.0 g (312 mmol) of a citraconic anhydride (CA), 0.0784 g (0.31 mmol,
0.1 mol% to the citraconic anhydride (CA)) of 4,4’-dichlorobenzophenone (DClBP) and
20 152 g (1,682 mmol, 4.33 wt times to the citraconic anhydride (CA)) of dimethyl
carbonate were charged, and dissolved with stirring by a magnetic stirrer. Then, the
17
resultant was irradiated with a 100 W high-pressure mercury lamp for 2 hours with
stirring at a temperature of from 10 to 15°C. After the irradiation, a reaction fluid was
quantitatively analyzed by gas chromatography, and as a result the remaining ratio of
the citraconic anhydride (CA) was 88.2%. Further, 0.2 g of the reaction fluid in a
reaction vessel was taken out, and a solvent was distilled off under a pressure of fro5 m
70 to 80 Torr by an evaporator. A crude product obtained was analyzed by 1H NMR
and confirmed to be a mixture (1,3-DM-CBDA:1,2-DM-CBDA = 43.3:56.7) containing
1,3-DM-CBDA and 1,2-DM-CBDA.
EXAMPLES 15 and 16
10 A series of operations was carried out in the same manner as in Example 14,
except that the amount of 4,4’-dichlorobenzophenone (DClBP) added was changed as
shown in the following Table. Further, the remaining ratio and the reaction rate of the
citraconic anhydride in a reaction fluid obtained herein, and the production ratio of 1,3-
DM-CBDA to 1,2-DM-CBDA, were calculated, and shown in Table together with the
15 results obtained in Comparative Example 11 and Example 14. Here, the reaction rate
in Comparative Example 11 in Table was calculated from the number of mole of the
citraconic acid used and the remaining ratio of the citraconic acid at the time when the
reaction was carried out for 6 hours, and the reaction rate in each of Examples 14 to 16
was calculated from the number of mole of the citraconic acid used and the remaining
20 ratio of the citraconic acid at the time when the reaction was carried out for 2 hours.
TABLE 3
Amount
of DCIBP
added
[mol%]
Photoradiation
time
[hr]
Citraconic anhydride Production ratio
(1H NMR)
Remaining
ratio (GC
quantity)
[%]
Reaction
rate
[mmol/hr]
1,3-DMCBDA
[mol%]
1,2-
DMCBDA
[mol%]
Comp.
Ex. 11
0 6 88.5 5.98 41.7 58.3
Ex. 14 0.1 2 88.2 18.44 43.3 56.7
Ex. 15 1 2 84.8 23.72 42.7 57.3
Ex. 16 5 2 85.7 22.36 40.0 60.0
EXAMPLE 17
In a nitrogen atmosphere, into a 300 mL Pyrex (registered trademark) glass five18
necked flask, 28.0 g (250 mmol) of a citraconic anhydride (CA), 0.313 g (1.25 mmol, 0.5
mol% to the citraconic anhydride (CA)) of 4,4’-dichlorobenzophenone (DClBP) and 158
g (1,799 mmol, 5.66 wt times to the citraconic anhydride (CA)) of dimethyl carbonate
were charged and dissolved with stirring by a magnetic stirrer. Then, the resultant was
irradiated with a 100 W high-pressure mercury lamp for 2 hours with stirring 5 at a
temperature of from 10 to 15°C. After the irradiation, a reaction fluid was quantitatively
analyzed by gas chromatography, and as a result the remaining ratio of the citraconic
anhydride (CA) was 79.7%. Further, 0.2 g of the reaction fluid in a reaction vessel was
taken out, and a solvent was distilled off under a pressure of from 70 to 80 Torr by an
10 evaporator. A crude product obtained was analyzed by 1H NMR and confirmed to be a
mixture (1,3-DM-CBDA:1,2-DM-CBDA = 43.9:56.1) containing 1,3-DM-CBDA and 1,2-
DM-CBDA.
EXAMPLE 18
A series of operations was carried out in the same manner as in Example 17
15 except that the amount of 4,4’-dichlorobenzophenone (DClBP) added was changed as
shown in the following Table. Further, the remaining ratio and the reaction rate of the
citraconic anhydride in a reaction fluid obtained herein, and the production ratio of 1,3-
DM-CBDA to 1,2-DM-CBDA, were calculated and shown in Table together with the
result obtained in Example 17. Here, the reaction rate in Table was calculated from the
20 number of mole of the citraconic acid used and the remaining ratio of the citraconic acid
at the time when the reaction was carried out for 2 hours.
TABLE 4
Amount of
DCIBP added
[mol%]
Citraconic anhydride Production ratio
(1H NMR)
Remaining
ratio of (GC
quantity)
[%]
Reaction
rate
[mmol/hr]
1,3-DMCBDA
[mol%]
1,2-DMCBDA
[mol%]
Ex. 17 0.5 79.7 25.38 43.9 56.1
Ex. 18 1 78.0 27.50 43.5 56.5
COMPARATIVE EXAMPLE 12
25 In a nitrogen atmosphere, into a 300 mL Pyrex (registered trademark) glass fivenecked
flask, 35.0 g (312 mmol) of a citraconic anhydride (CA) and 152 g (1,682 mmol,
19
4.33 wt times to the citraconic anhydride (CA)) of dimethyl carbonate were charged and
dissolved with stirring by a magnetic stirrer. Then, the resultant was irradiated with a
100 W high-pressure mercury lamp for 48 hours with stirring at a temperature of from 10
to 15°C. A reaction fluid was analyzed by gas chromatography, and the remaining ratio
of the raw material was confirmed to be 23.7%. Thereafter, a white crystal precipitate5 d
was obtained by filtration at a temperature of from 10 to 15°C, and this crystal was
washed twice with 43.8 g (497 mmol, 1.25 wt times to the citraconic anhydride (CA)) of
ethyl acetate. Then, this crystal was dried under reduced pressure to obtain 8.1 g
(yield: 23.2%) of a white crystal. This crystal was analyzed by 1H NMR and confirmed
10 to be a mixture (1,3-DM-CBDA:1,2-DM-CBDA = 90.3:9.7) containing 1,3-DM-CBDA and
1,2-DM-CBDA. Further, a crystal, a filtrate and a washing liquid obtained were
quantitatively analyzed respectively by 1 H NMR analysis and gas chromatography.
Mass balance to the charged amount was 88.9%.
EXAMPLE 19
15 In a nitrogen atmosphere, into a 300 mL Pyrex (registered trademark) glass fivenecked
flask, 28.0 g (250 mmol) of citraconic anhydride (CA), 0.628 g (2.50 mmol, 1.0
mol% to the citraconic anhydride (CA)) of 4,4’-dichlorobenzophenone (DClBP) and 158
g (1,799 mmol, 5.66 wt times to the citraconic anhydride (CA)) of dimethyl carbonate
were charged and dissolved with stirring by a magnetic stirrer. Then, the resultant was
20 irradiated with a 100 W high-pressure mercury lamp for 14 hours with stirring at a
temperature of from 10 to 15°C. A reaction fluid was analyzed by gas chromatography,
and the remaining ratio of the raw material was confirmed to be 3.8%. Thereafter, a
white crystal precipitated was obtained by filtration at a temperature of from 10 to 15°C,
and this crystal was washed twice with 35.0 g (397 mmol, 1.25 wt times to the citraconic
25 anhydride (CA)) of ethyl acetate. Then, this crystal was dried under reduced pressure
to obtain 6.9 g (yield: 24.7%) of a white crystal. This crystal was analyzed by 1 H NMR
and confirmed to be a mixture (1,3-DM-CBDA:1,2-DM-CBDA = 91.8:8.2) containing 1,3-
DM-CBDA and 1,2-DM-CBDA. Further, a crystal, a filtrate and a washing liquid
obtained were quantitatively analyzed respectively by 1H NMR analysis and gas
30 chromatography. Mass balance to the charged amount was 90.2%.
REFERENCE EXAMPLE 1
20
1,3-DM-CBDA
O O
O O
O O
1,2-DM-CBDA
O O
O O
O O
Ac2O
1,3-DM-CBDA
O O
O O
O O
reflux
In a nitrogen stream, into a 5 L four-necked flask, 700 g of a mixture (1,3-DMCBDA:
1,2-DM-CBDA = 92:8) containing 1,3-DM-CBDA and 1,2-DM-CBDA, obtained in
the same manner as in Comparative Example 12 and 3,500 g of acetic anhydride were
5 charged and suspended at 25°C with stirring by a magnetic stirrer, followed by heat
reflux (130°C) for 4 hours, and then cooled so that the internal temperature would be
25°C or lower, followed by stirring for one hour at a temperature of 25°C or lower.
Then, a white crystal precipitated was filtrated, and a crystal obtained was washed twice
with 700 g of ethyl acetate. Thereafter, a white crystal obtained was dried under
10 reduced pressure to obtain 634 g (recovery rate: 91%) of a high purity 1,3-DM-CBDA.
The crystal was analyzed by 1H NMR, whereby the ratio of 1,3-DM-CBDA to 1,2-DMCBDA
was confirmed to be 1,3-DM-CBDA:1,2-DM-CBDA = 99.5:0.5.
1 H NMR ( DMSO-d6, δ ppm ) ( 1,3-DM-CBDA ): 1.38 ( s, 6H ), 3.89 ( s, 2H ).
1 H NMR ( DMSO-d6, δ ppm ) ( 1,2-DM-CBDA ): 1.37 ( s, 6H ), 3.72 ( s, 2H ).
15 mp. ( 1,3-DM-CBDA ): 316.45°C
X-ray structural analysis of single crystal (1,3-DM-CBDA): Fig. 1 shows a
molecular model arranged on the basis of X-ray structural analysis of a single crystal.
The single crystal for analyzing X-ray structure was prepared in such a manner that 1,3-
DM-CBDA obtained by the above method was dissolved in ethyl acetate, and n-hexane
20 as a poor solvent was dropwisely added thereto.
Molecular formula: C1 0H8O6 , molecular weight: 224.16 , crystal system:
Orthorhombic, space group: Pbca , lattice constant; a = 11.2988(3)Å, b = 6.9330(2)Å, c
= 12.1220(4)Å, =90°, =90°, =90°, Z value =4, R(gt)=0.11, wR(gt)=0.32.
EXAMPLE 20
1,3-DM-CBDA
O O
O O
O O
1,2-DM-CBDA
O O
O O
O O
Ac2O
1,3-DM-CBDA
O O
O O
O O
reflux
25
In a nitrogen stream, into a 200 mL four-necked flask, 18.3 g of a mixture (1,3-DM21
CBDA:1,2-DM-CBDA = 85:15) containing 1,3-DM-CBDA and 1,2-DM-CBDA, obtained in
the same manner as in Example 19, and 92 g of acetic anhydride were charged and
suspended at 25°C with stirring by a magnetic stirrer, followed by heat reflux (130°C) for
4 hours, and then cooled so that the internal temperature would be 25°C or lower,
followed by stirring for one hour at a temperature of 25°C or lower. Then, a whit5 e
crystal precipitated was filtrated, and a crystal obtained was washed twice with 18 g of
ethyl acetate. Thereafter, a white crystal precipitated was dried under reduced
pressure to obtain 14.4 g (recovery rate: 92%) of a high purity 1,3-DM-CBDA. The
crystal was analyzed by 1H NMR, whereby the ratio of 1,3-DM-CBDA to 1,2-DM-CBDA
10 was confirmed to be 1,3-DM-CBDA:1,2-DM-CBDA = 99.5:0.5.
1 H NMR ( DMSO-d6, δ ppm ) ( 1,3-DM-CBDA ): 1.38 ( s, 6H ), 3.89 ( s, 2H ).
1 H NMR ( DMSO-d6, δ ppm ) ( 1,2-DM-CBDA ): 1.37 ( s, 6H ), 3.72 ( s, 2H ).
mp. ( 1,3-DM-CBDA ): 316.82°C
X-ray structural analysis of single crystal (1,3-DM-CBDA): Fig. 2 shows a
15 molecular model arranged on the basis of X-ray structural analysis of a single crystal.
The single crystal for analyzing X-ray structure was prepared in such a manner that 1,3-
DM-CBDA obtained by the above method was dissolved in ethyl acetate, and n-hexane
as a poor solvent was dropwisely added thereto.
Molecular formula: C1 0H8O6 , molecular weight: 224.16, crystal system:
20 Orthorhombic, space group: Pbca, lattice constant: a = 11.3082(8)Å, b = 6.9168(6)Å, c =
12.1479(9)Å, =90°, β=90°, γ=90°, Z value =4, R(gt)=0.1192, wR(gt)=0.3183.
COMPARATIVE EXAMPLE 13
O
O
O
h
CBDA
O O
O O
O O
AcOEt
MA
In a nitrogen atmosphere, into a 30 mL Pyrex (registered trademark) glass test
25 tube, 0.10 g (1.02 mmol) of maleic anhydride (MA) and 20 g (227 mmol, 200 wt times to
the maleic anhydride (MA)) of ethyl acetate were charged and dissolved with stirring by
a magnetic stirrer. Thereafter, the resultant was irradiated with a 100 W high-pressure
mercury lamp for one hour with stirring at a temperature of from 5 to 10°C. After the
irradiation, a reaction fluid was quantitatively analyzed by gas chromatography, and as a
22
result, the remaining ratio of the maleic anhydride (MA) was 72.4%. Further, 2 g of the
reaction fluid in a reaction vessel was taken out, and a solvent was distilled off under a
pressure of from 70 to 80 Torr by an evaporator. A crude product obtained was
analyzed by 1H NMR and confirmed to be a mixture containing CBDA.
1 H NMR ( DMSO-d6, δ ppm ) ( CBDA ): 3.87 5 ( s, 4H ).
COMPARATIVE EXAMPLE 14
O
O
O h
BP
CBDA
O O
O O
O O
AcOEt
MA
In a nitrogen atmosphere, into a 30 mL Pyrex (registered trademark) glass test
tube, 0.10 g (1.02 mmol) of maleic anhydride (MA), 0.0186 g (0.102 mmol, 10 mol% to
10 the maleic anhydride (MA)) of benzophenone (BP) and 20 g (227 mmol, 200 wt times to
maleic anhydride (MA)) of ethyl acetate were charged and dissolved with stirring by a
magnetic stirrer. Thereafter, the resultant was irradiated with a 100 W high-pressure
mercury lamp for one hour with stirring at a temperature of from 5 to 10°C. After the
irradiation, a reaction fluid was quantitatively analyzed by gas chromatography, and as a
15 result, the remaining ratio of the maleic anhydride (MA) was 80.3%. Further, 2 g of the
reaction fluid in a reaction vessel was taken out, and a solvent was distilled off under a
pressure of from 70 to 80 Torr by an evaporator. A crude product obtained was
analyzed by 1H NMR and confirmed to be a mixture containing CBDA.
COMPARATIVE EXAMPLES 15 to 16 and EXAMPLES 21 to 27
20 A series of operations was carried out in the same manner as in Comparative
Example 14 except that 10 mol% of each sensitizer was added to maleic anhydride
(MA). The type of each sensitizer added and a result thereof are shown in the
following Table. Further, the remaining ratio and the reaction rate of the maleic
anhydride in a reaction fluid obtained were calculated.
25 Their results are shown in Table 5 together with the results obtained in
Comparative Examples 13 and 14. Here, the reaction rate in Table was calculated
from the number of mole of the maleic anhydride used and the remaining ratio of the
maleic anhydride at the time when the reaction was carried out for one hour.
23
TABLE 5
sensitizer
[10 mol%]
Maleic anhydride
Remaining
ratio of (GC
quantity)
[%]
Reaction
rate
[mmol/hr]
Comp. Ex. 13 - 72.4 0.28
Comp. Ex. 14 Benzophenone 80.3 0.20
Comp. Ex. 15 Acetophenone 89.1 0.11
Comp. Ex. 16 4,4'-dimethoxybenzophenone 89.3 0.11
Ex. 21 4-chlorobenzophenone 64.5 0.36
Ex. 22 2,4'-dichlorobenzophenone 55.6 0.45
Ex. 23 4,4'-dichlorobenzophenone 35.3 0.66
Ex. 24 4,4'-difluorobenzophenone 35.7 0.66
Ex. 25 4-cyanobenzophenone 49.4 0.52
Ex. 26 1,3-bis(4-fluorobenzoyl)benzene 45.8 0.55
Ex. 27 Anthraquinone 65.0 0.36
As is clear from Table 5, it is found that the reaction rate is higher in any of
Examples 21 to 27 using benzophenone substituted with an electron-withdrawing group,
than Comparative Example 13 using no sensitizer, Comparative Examples 14 and 5 d 15
using non-substituted benzophenone or acetophenone, and Comparative Example 16
using benzophenone substituted with an electron donating group.
INDUSTRIAL APPLICABILITY
10 The cyclobutane tetracarboxylic acid derivative obtained in the present invention is
a compound useful as a raw material for e.g. a polyimide, and such a polyimide is
industrially applicable as a resin composition used in the field of a display such as a
television employing a liquid crystal panel or a semiconductor field.
15 The entire disclosure of Japanese Patent Application No. 2014-007184 filed on
January 17, 2014 including specification, claims, drawings and summary is incorporated
herein by reference in its entirety.
24
CLAIMS
1. A method for producing a 1,2,3,4-cyclobutane tetracarboxylic acid-1,2:3,4-
dianhydride derivative represented by the formula (2), comprising:
subjecting a maleic anhydride compound represented by the following formula (1)
to a photodimerization reaction, in the presence of benzophenone substituted with 5 an
electron-withdrawing group, acetophenone substituted with an electron-withdrawing
group or benzaldehyde substituted with an electron-withdrawing group.
wherein R is a hydrogen atom or a C1-20 alkyl group.
2. The method according to Claim 1, wherein R is a methyl group.
10 3. The method according to Claim 1, wherein R is a hydrogen atom.
4. The method according to any one of Claims 1 to 3, wherein the electronwithdrawing
group is at least one member selected from the group consisting of a fluoro
group, a chloro group, a bromo group, an iodo group, a nitro group, a cyano group and
a trifluoromethyl group.
15 5. The method according to any one of Claims 1 to 4, wherein the number of
electron-withdrawing groups is from 1 to 5.
6. The method according to any one of Claims 1 to 5, wherein the proportion of
benzophenone substituted with an electron-withdrawing group, acetophenone
substituted with an electron-withdrawing group or benzaldehyde substituted with an
20 electron-withdrawing group to the maleic anhydride compound, is from 0.1 to 20 mol%.
7. The method according to any one of Claims 1 to 6, wherein the
photodimerization reaction is carried out in a reaction solvent.
8. The method according to Claim 7, wherein the reaction solvent is an ester or an
anhydride of an organic carboxylic acid, or a carbonic acid ester.
25 9. The method according to Claim 7 or 8, wherein the reaction solvent is ethyl
acetate or dimethyl carbonate.10. The method according to any one of Claims 7 to 9, wherein the reaction solvent is
used in an amount of from 3 to 300 times by mass to the maleic anhydride compound.
11. The method according to any one of Claims 7 to 9, wherein the amount of the
reaction solvent to be used is from 3 to 10 times by mass to the maleic anhydride
compound.
12. The method according to anyone of Claims 1 to 11, wherein the reaction
temperature is from 0 to 20°C.