DESCRIPTION
TITLE OF INVENTION:
METHOD FOR PRODUCING CYCLOBUTANE TETRACARBOXYLIC ACID
DERIVATIVE
5
TECHNICAL FIELD
The present invention relates to a method for producing an alicyclic tetracarboxylic
acid anhydride which can be a raw material monomer for e.g. a polyimide for an optical
material.
10
BACKGROUND ART
In general, polyimide resins are widely used as electronic materials such as
protective materials or insulating materials, in liquid crystal display elements or
semiconductors, by virtue of their characteristics such as high mechanical strength, heat
15 resistance, insulating properties and solvent resistance. Further, they are recently
expected to be used as optical communication materials such as optical waveguide
materials.
In recent years, developments in this field are remarkable, and along with such
developments, materials to be used are also required to have increasingly higher
20 properties. That is, they are expected not only to be excellent in heat resistance and
solvent resistance but also to have various properties depending upon the particular
applications.
However, in the case of a wholly aromatic polyimide resin obtained from an
aromatic tetracarboxylic acid anhydride and an aromatic diamine as raw materials, it
25 has a deep amber color, which brings about a problem in its use as an optical material
where high transparency is required. On the other hand, in the case of a polyimide
resin obtained by imidating a polyimide precursor formed by a polycondensation
reaction of an alicyclic tetracarboxylic acid anhydride and an aromatic diamine, whereby
it is possible to obtain a polyimide having high transparency with relatively little
30 coloration (Patent Documents 1 and 2).
Patent Document 3 discloses that, as an alkylcyclobutanoic acid dianhydride
which is one of alicyclic tetracarboxylic acid anhydrides as raw materials for the above
2
polyamide having high transparency with relatively little coloration, it is possible to
obtain a mixture of 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2:3,4-
dianhydride (1,3-DMCBDA) and 1,2-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid-
1,2:3,4-dianhydride (1,2-DMCBDA) by photodimerization reaction of citraconic
anhydride (abbreviated as MMA) as represented by the following 5 scheme.
Meanwhile, when 1,3-DMCBDA and 1,2-DMCBDA are compared, it is known that
the former 1,3-DMCBDA, which is an isomer having a highly symmetric structure, is
more useful since it is possible to produce a polyimide having a higher molecular weight
10 than the latter 1,2-DMCBDA.
Although Patent Document 3 discloses that it is possible to obtain a mixture of 1,3-
DMCBDA and 1,2-DMCBDA, it fails to disclose that the former 1,3-DMCBDA, which is
an isomer having a higher symmetric structure and a higher utility, is selectively
produced in a high yield.
15
PRIOR ART DOCUMENTS
PATENT DOCUMENTS
Patent Document 1: JP-B-2-24294
Patent Document 2: JP-A-58-208322
20 Patent Document 3: JP-A-4-106127
DISCLOSURE OF INVENTION
TECHNICAL PROBLEM
The object of the present invention is to provide a novel method for producing a
25 1,3-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2:3,4-dianhydride (hereinafter, also
referred to as 1,3-DACBDA), which is an isomer having a higher symmetric structure
and a higher utility than a 1,2-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2:3,4-
dianhydride (hereinafter, also referred to as 1,2-DACBDA), in an improved selectivity
3
and further in a high yield as compared with a conventional method, by subjecting a
specific maleic anhydride compound as a raw material to photodimerization reaction.
SOLUTION TO PROBLEM
The present inventors have conducted extensive studies to solve the 5 e above
problems and as a result, have found a novel production method for achieving the
above object, whereby they have accomplished the present invention.
The present invention provides the following.
1. A method for producing a 1,2,3,4-cyclobutane tetracarboxylic acid-1,2:3,4-
10 dianhydride derivative (1,3-DACBDA) represented by the formula (2), which comprises
subjecting a maleic anhydride compound represented by the following formula (1) to a
photodimerization reaction, in a reaction solvent in an amount of at least 100 times by
mass to the maleic anhydride compound.
15 wherein R is 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 or 2, wherein the photodimerization reaction
is carried out in the reaction solvent in an amount of from 100 to 300 times by mass to
the maleic anhydride compound.
20 4. The method according to the above 1 or 2, wherein the photodimerization reaction
is carried out in the reaction solvent in an amount of from 150 to 250 times by mass to
the maleic anhydride compound.
5. The method according to any one of the above 1 to 4, wherein the reaction solvent
is an ester or an anhydride of an organic carboxylic acid, or a carbonic acid ester.
25 6. The method according to any one of the above 1 to 5, wherein the reaction solvent
is ethyl acetate or dimethyl carbonate.
7. The method according to any one of the above 1 to 6, which is carried out in the
4
presence of a sensitizer made of benzophenone, acetophenone, benzaldehyde,
benzophenone substituted with an electron-withdrawing group, acetophenone
substituted with an electron-withdrawing group, benzaldehyde substituted with an
electron-withdrawing group or anthraquinone.
8. The method according to the above 7, wherein the electron-withdrawing group 5 oup 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.
9. The method according to the above 7 or 8, wherein the number of electron10
withdrawing groups is from 1 to 5.
10. The method according to any one of the above 6 to 9, wherein the sensitizer is
used in a proportion of from 0.1 to 20 mol% to the maleic anhydride compound.
11. The method according to any one of the above 1 to 10, wherein the reaction
temperature is from 0 to 20 C.
15
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, by subjecting a specific maleic anhydride
compound to a photodimerization reaction, it is possible to increase the selectivity of
1,3-DACBDA, which is an isomer having a higher symmetric structure and a higher
20 utility, and further it is possible to increase the conversion rate of the maleic anhydride
compound by a photodimerization reaction, as compared with a conventional method,
and as a result, it is possible to provide a method for producing 1,3-DACBDA in a high
yield, although it is a mixture of 1,3-DACBDA and 1,2-DACBDA.
25 DESCRIPTION OF EMBODIMENTS
The method for producing a 1,2,3,4-cyclobutanetetracarboxylic acid-1,2:3,4-
dianhydride (1,3-DACBDA) 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.
5
wherein R is a C1-20, preferably C1-12, particularly preferably C1-6 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, a saturated alkyl group such as methyl, ethyl, n-propyl, 5 ipropyl,
n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, 1-methyl-n-butyl, 2-methyl-n-butyl, 3-
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 or n-eicosyl, or an unsaturated alkyl group such as 1-methylvinyl, 2-
10 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-dodecenyl, 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
15 represents tertiary, respectively.
The maleic anhydride compound represented by the formula (1) may, for example,
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-n20
nonyl 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
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-
25 butynyl) maleic anhydride, 2-(3-methyl-2-propynyl) maleic anhydride or 2-(9-decynyl)
maleic anhydride. Among them, e.g. citraconic anhydride, 2-ethyl maleic anhydride, 2-
isopropyl maleic anhydride, 2-n-butyl maleic anhydride, 2-t-butyl maleic anhydride, 2-n6
pentyl maleic anhydride, 2-n-hexyl maleic anhydride, 2-n-heptyl maleic anhydride, 2-noctyl
maleic anhydride, 2-n-nonyl maleic anhydride, 2-n-decyl maleic anhydride or 2-ndodecyl
maleic anhydride is preferred, and 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 or 2-n-hexyl maleic anhydride is more preferre5 d,
in view of high photoreaction efficiency.
As a reaction solvent, an organic solvent commonly used for a photochemical
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
10 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
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
15 having no low-boiling point as to increase the risk of flammability and further having a
boiling point of around 50 to 150°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) to be available at a low cost. In order to meet these
requirements, as the reaction solvent, hexane, heptane, acetonitrile, acetone or
20 chloroform may, for example, be also used. As the reaction solvent, an ester or an
anhydride of an organic carboxylic acid or a carbonic acid ester is preferred as the
reaction solvent.
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
25 alkyl group, more preferably a C1-2 alkyl group, and R2 is a C1-4 alkyl group, more
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
30 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,
7
be used.
Further, the anhydride of an organic carboxylic acid is preferably one represented
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, aceti5 c
anhydride is preferred from the viewpoint that it is possible to obtain 1,3-DACBDA in a
higher yield.
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
10 carbonate, diethyl carbonate, dipropyl carbonate or a mixture thereof may be
mentioned.
Among them, a preferred reaction solvent may be ethyl formate, methyl acetate,
ethyl acetate, i-propyl acetate, i-butyl acetate, methyl propionate, ethyl propionate, npropyl
propionate, i-propyl propionate, ethylene glycol diformate, ethylene glycol
15 diacetate, dimethyl carbonate or diethyl carbonate, and a most preferred solvent is ethyl
acetate or dimethyl carbonate.
The solvent may be used alone or in combination of two or more, but it is
advantageous to use the solvent alone in view of easiness of treatment after the
reaction.
20 In the present invention, in a case where the reaction solvent contains ethyl
acetate, dimethyl carbonate, diethyl carbonate or ethylene glycol diacetate, the solubility
of a 1,3-DACBDA produced is low despite that the solubility of the maleic anhydride
compound as a raw material is high, whereby a desired compound is precipitated as a
crystal during the reaction, and therefore it is possible to suppress a reverse reaction
25 from DACBDA to the maleic anhydride compound or a side reaction such as production
of oligomer.
In the present invention, the amount of the reaction solvent to be used is
important, and when an extremely large amount of the reaction solvent is used, a high
selectivity of 1,3-DACBDA in a mixture of 1,3-DACBDA and 1,2-DACBDA produced is
30 achieved. That is, when the reaction solvent is present in an amount of at least 100
times by mass, preferably from 100 to 300 times by mass, more preferably from 150 to
250 times by mass to a maleic anhydride compound as a raw material, the selectivity of
8
1,3-DACBDA becomes high, whereby it is possible to obtain a product having a large
content of 1,3-DACBDA, as compared with a conventional method.
In the photoreaction of the present invention, 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 low-pressure mercury lamp, a medium-pressure mercur5 y
lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon
lamp, an electrodeless lamp or a light-emitting diode, etc. is preferred since it is possible
to obtain a CBDA derivative compound in a particularly high yield.
Further, with respect to a photochemical reaction apparatus, if a light source10
cooling pipe is changed from lime glass to Pyrex (registered trademark) glass, a colored
polymer is less attached to the light source-cooling pipe and impurities are less
produced, and therefore it is possible to improve the yield of a CBDA derivative
compound.
If the reaction temperature becomes high, a polymer tends to be produced as a
15 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
20°C, the production of a by-product is significantly suppressed, and therefore it is
20 possible to obtain 1,3-DACBDA in a high selectivity and high 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
anhydride compound reaches preferably a range of from 0 to 40%, more preferably a
25 range of from 0 to 10%.
The reaction time is usually from 1 to 200 hours, preferably from 1 to 100 hours,
more preferably from 1 to 60 hours.
Further, the conversion rate may easily be obtained by analyzing a reaction fluid
by e.g. gas chromatography.
30 As the reaction time becomes long, the conversion rate of a maleic anhydride
compound increases and the precipitation amount of a CBDA derivative compound
thereby increases, and as a result, the CBDA derivative compound produced tends to
9
attach to an exterior wall (a reaction fluid side) of a light source-cooling pipe, whereby
crystal coloration or a decrease of light efficiency (unit power × yield per hour)
accompanied by decomposition reaction tends to be observed. Therefore, it is
practically undesirable to take a long time in one batch for increasing the conversion
rate of the maleic anhydride compound since the production efficiency decr5 eases.
Further, the reaction may be carried out by either a batch-type or a flow-type, but a
batch-type is preferably used. Further, the reaction pressure may be either
atmospheric pressure or elevated pressure, but is preferably atmospheric pressure.
Further, the production method of the present invention may be carried out by
10 adding a sensitizer. The sensitizer may, for example, be benzophenone,
acetophenone, benzaldehyde, anthraquinone, benzophenone substituted with an
electron-withdrawing group, acetophenone substituted with an electron-withdrawing
group or benzaldehyde substituted with an electron-withdrawing group.
The electron-withdrawing group may be at least one member selected from the
15 group consisting of a fluoro group, a chloro group, a bromo group, an iodine group, a
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
20 5, particularly preferably from 1 to 3.
The substitution position of the electron-withdrawing group may be ortho position,
meta position or para position, preferably ortho position or para position, to the carbonyl
group.
When the number of the electron-withdrawing group is two or more, the electron25
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 or benzophenone substituted with an
electron-withdrawing group, benzophenone, 2-fluorobenzophenone, 3-
30 fluorobenzophenone, 4-fluorobenzophenone, 2-chlorobenzophenone, 3-
chlorobenzophenone, 4-chlorobenzophenone, 2-cyanobenzophenone, 3-
cyanobenzophenone, 4-cyanobenzophenone, 2-nitrobenzophenone, 3-
10
nitrobenzophenone, 4-nitrobenzophenone, 2,4’-dichlorobenzophenone, 4,4’-
difluorobenzophenone, 4,4’-dichlorobenzophenone, 4,4’-dibromobenzophenone, 3,3’-
bis(trifluoromethyl)benzophenone, 3,4’-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-dibenzoylbenzonitrile5 ,
1,3-dibenzoyl-4,6-dinitrobenzene or anthraquinone may be mentioned. Among them,
4,4’-difluorobenzophenone or 4,4’-dichlorobenzophenone is preferred.
As a specific example of acetophenone or acetophenone substituted with an
electron-withdrawing group, acetophenone, 2’-fluoroacetophenone, 3’-
10 fluoroacetophenone, 4’-fluoroacetophenone, 2’-chloroacetophenone, 3’-
chloroacetophenone, 4’-chloroacetophenone, 2’-cyanoacetophenone, 3’-
cyanoacetophenone, 4’-cyanoacetophenone, 2’-nitroacetophenone, 3’-
nitroacetophenone, 4’-nitroacetophenone, 2’,4’-difluoroacetophenone, 3’,4’-
difluoroacetophenone, 2’,4’-dichloroacetophenone, 3’,4’-dichloroacetophenone, 4’-
15 chloro-3’-nitroacetophenone, 4’-bromo-3’-nitroacetophenone or 4’-fluoro-3’-
nitroacetophenone may, for example, be mentioned. Among them, 4’-
fluoroacetophenone, 4’-chloroacetophenone, 2’,4’-difluoroacetophenone, 3’,4’-
difluoroacetophenone, 2’,4’-dichloroacetophenone or 3’,4’-dichloroacetophenone is
preferred.
20 Benzaldehyde or benzaldehyde substituted with an electron-withdrawing group
may, for example, be benzaldehyde, 2-fluorobenzaldehyde, 3-fluorobenzaldehyde, 4-
fluorobenzaldehyde, 2-chlorobenzaldehyde, 3-chlorobenzaldehyde, 4-
chlorobenzaldehyde, 2-cyanobenzaldehyde, 3-cyanobenzaldehyde, 4-
cyanobenzaldehyde, 2-nitrobenzaldehyde, 3-nitrobenzaldehyde, 4-nitrobenzaldehyde,
25 2,4-difluorobenzaldehyde, 3,4-difluorobenzaldehyde, 2,4-dichlorobenzaldehyde, 3,4-
dichlorobenzaldehyde, 2-chloro-5-nitrobenzaldehyde, 4-chloro-2-nitrobenzaldehyde, 4-
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,
30 3,4-difluorobenzaldehyde, 2,4-dichlorobenzaldehyde or 3,4-dichlorobenzaldehyde is
preferred.
The amount of the sensitizer to be used is not particularly limited so long as it is
11
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.
As the sensitizer, the above benzophenone derivative, acetophenone derivative or
benzaldehyde derivative may be used alone or two or more of them may be used in
combination, but when it is used alone, treatment after the reaction is easy5 .
The desired compound may be obtainable by carrying out photoreaction, filtrating
a precipitate in a reaction fluid, washing a collected product with an organic solvent,
folowed by drying under reduced pressure.
The amount of the organic solvent to be used for washing the collected product, is
10 not limited so long as it is possible to transfer a precipitate remained in a reactor to a
filter, but if the amount of the organic solvent is large, the desired compound tends to be
transferred to a filtrate, whereby the recovery rate 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
15 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, the organic solvent to be used for washing the collected
20 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, npropyl
propionate, i-propyl propionate, n-butyl propionate, i-butyl propionate, ethylene
glycol diformate, ethylene glycol diacetate, ethylene glycol dipropionate, dimethyl
25 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 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.
30
EXAMPLES
Now, the present invention will specifically be described with reference to
12
Examples, but it should be understood that the present invention is by no means
restricted thereto. Further, analytical methods employed in Examples are as follows.
(GC analytical conditions>
Apparatus: GC-2010 Plus (manufactured by SHIMADZU Corporation),
Column: DB-1 (manufactured by GL Sciences Inc.,) diameter 0.25 mm × 5 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 lactate.
10 <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).

15 Apparatus: DSC1 (manufactured by Mettler-Toredo International Inc.),
Temperature: 35°C-5°C/min-400°C, Pan: Au (closed).
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
20 tube, 0.10 g (0.89 mmol) of a citraconic anhydride (CA), 20 g (222 mmol, 200 times by
weight 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. Then, 2 g of the reaction fluid in a reaction vessel was taken out, and a
25 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 ).
1 H NMR ( DMSO-d6, δ ppm ) ( 1,2-DM-CBDA ): 1.37 ( s, 6H ), 3.72 ( s, 2H ).
13
mp. (1,3-DM-CBDA):316-317°C
EXAMPLES 2 to 7 and COMPARATIVE EXAMPLES 1 to 5
A series of operations was carried out in the same manner as in Example 1 except
that the type of a solvent, the presence or absence of addition of DClBP, the charged
amount of a citraconic anhydride (CA) and the amount of a solvent, were 5 changed as
shown in the following Table 1. Further, the production ratio (1,3-DM-CBDA:1,2-DMCBDA)
of 1,3-DM-CBDA to 1,2-DM-CBDA, were calculated in the same manner as in
Example 1.
The type of a solvent, the presence or absence of addition of DClBP, the charged
10 amount of CA, the amount of a solvent and a result are shown in the following Table.
Further, the production ratio of 1,3-DM-CBDA to 1,2-DM-CBDA in a reaction fluid
obtained herein, were calculated, and shown in Table together with the results obtained
in Example 1. Further, in Table 1, “Neat” represents that the operation was carried out
by using no solvent. Further, DCIBP was used in a proportion of from 0.1 to 10 mol%
15 to the citraconic anhydride.
14
TABLE 1
Solvent
Addition of
DCIBP
Charged
amount of CA
Amount of solvent Production ratio (1H NMR)
[mmol] [times by mass vs CA]
1,3-DM-CBDA
[mol%]
1,2-DM-CBDA
[mol%]
Ex. 1 Dimethyl carbonate Absence 0.89 200.0 48.3 51.7
Ex. 2 Dimethyl carbonate Presence 0.89 200.0 48.3 51.7
Ex. 3 Dimethyl carbonate Presence 249.82 5.7 40.8 59.2
Comp. Ex. 1 Dimethyl carbonate Absence 312.28 4.3 41.7 58.3
Comp. Ex. 2 Dimethyl carbonate Absence 53.53 1.0 39.1 60.9
Comp. Ex. 3 Dimethyl carbonate Absence 71.38 0.3 36.5 63.5
Ex. 4 Ethyl acetate Absence 0.89 200.0 40.5 59.5
Ex. 5 Ethyl acetate Absence 6.96 39.0 35.8 64.2
Ex. 6 Ethyl acetate Presence 6.96 39.0 36.0 64.0
Ex. 7 Ethyl acetate Presence 423.80 3.0 34.4 65.6
Comp. Ex. 4 Ethyl acetate Absence 312.28 4.3 32.5 67.5
Comp. Ex. 5 Neat Absence 107.07 0 35.0 65.0
15
INDUSTRIAL APPLICABILITY
1,3-DACBDA as a cyclobutane carboxylic acid derivative obtained in the present
invention is a compound useful as a raw material for e.g. a polyamic acid or a polyimide,
and such a polyimide is industrially widely useful as a resin composition used for
electronic materials such as protective materials or insulating materials, in liquid crysta5 l
display elements or semiconductors.
The entire disclosure of Japanese Patent Application No. 2014-007185 filed on
January 17, 2014 including specification, claims and summary is incorporated herein by
10 reference in its entirety.
16

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), which comprises subjecting a
maleic anhydride compound represented by the following formula (1) to a
photodimerization reaction, in a reaction solvent in an amount of at least 100 times 5 mes by
mass to the maleic anhydride compound.
wherein R is 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 or 2, wherein the photodimerization reaction is
carried out in the reaction solvent in an amount of from 100 to 300 times by mass to the
maleic anhydride compound.
4. The method according to Claim 1 or 2, wherein the photodimerization reaction is
carried out in the reaction solvent in an amount of from 150 to 250 times by mass to the
15 maleic anhydride compound.
5. The method according to any one of Claims 1 to 4, wherein the reaction solvent is
an ester or an anhydride of an organic carboxylic acid, or a carbonic acid ester.
6. The method according to any one of Claims 1 to 5, wherein the reaction solvent is
ethyl acetate or dimethyl carbonate.
20 7. The method according to any one of Claims 1 to 6, which is carried out in the
presence of a sensitizer made of benzophenone, acetophenone, benzaldehyde,
benzophenone substituted with an electron-withdrawing group, acetophenone
substituted with an electron-withdrawing group, benzaldehyde substituted with an
electron-withdrawing group or anthraquinone.
25 8. The method according to Claim 7, wherein the electron-withdrawing 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.17
9. The method according to Claim 7 or 8, wherein the number of electronwithdrawing
groups is from 1 to 5.
10. The method according to any one of Claims 7 to 9, wherein the sensitizer is used
in a proportion of from 0.1 to 20 mol% to the maleic anhydride compound.
11. The method according to any one of Claims 1 to 10, wherein the reaction
temperature is from 0 to 20°C.