DESCRIPTION
TITLE OF INVENTION:
METHOD FOR PRODUCING CYCLOBUTANE TETRACARBOXYLIC ACID AND
ANHYDRIDE THEREOF
5
TECHNICAL FIELD
The present invention relates to a novel method for producing a cyclobutane
tetracarboxylic acid and an anhydride thereof.
BACKGROUND AR10 T
Tetracarboxylic acid derivatives such as a tetracarboxylic acid dialkyl ester are
important substances which will be raw materials for polyamides, polyesters or
polyimides.
For example, as a preparation example for a polyimide having a cyclobutane
15 structure in its main chain, a case has been reported wherein a
bis(chlorocarbonyl)cyclobutanedicarboxylic acid dimethyl ester is reacted with a diamine
to obtain a polyamic acid methyl ester, which is then heated to obtain a polyimide (Non-
Patent Document 1).
Further, as cyclobutanetetracarboxylic acids having substituents on a cyclobutane
20 ring, Patent Document 1 has reported a cyclobutane tetracarboxylic acid dialkyl ester
and a bis(chlorocarbonyl) compound prepared by chlorinating it.
Although Patent Document 1 discloses that it is possible to obtain a desired
cyclobutane tetracarboxylic acid dialkyl ester derivative in a high yield, it fails to disclose
that a residue formed in a process for producing a desired cyclobutane tetracarboxylic
25 acid dialkyl ester, is used to recover a useful material such as a cyclobutane
tetracarboxylic acid dianhydride as a starting material.
PRIOR ART DOCUMENTS
PATENT DOCUMENTS
30 Patent Document 1: WO2010/092989
NON-PATENT DOCUMENTS
Non-Patent Document 1: High Performance Polymers, (1998), 10(1), p.11-21
2
DISCLOSURE OF INVENTION
TECHNICAL PROBLEM
It is an object of the present invention to provide a novel method for obtaining, as
a useful material, a cyclobutane tetracarboxylic acid and/or a dianhydride thereof simply
with a high efficiency, by using, as a raw material, a residue formed after separation of 5 a
desired product produced in a process for producing e.g. a cyclobutane tetracarboxylic
acid derivative.
SOLUTION TO PROBLEM
10 The present invention is one to solve the above problem and provides the
following.
1. A method for producing a tetracarboxylic acid represented by the formula [7],
which comprises subjecting a mixture of a tetracarboxylic acid dialkyl ester represented
by the formula [1] and a tetracarboxylic acid dialkyl ester represented by the formula [2],
15 to hydrolysis, in a solvent.
wherein R1 is a C1-5 alkyl group, R2 is a C1-5 alkyl group, n is 2 or 4, and R1 and R2 may
be the same or different,
wherein R2 and n are as defined above.
2. A method for producing an acid dianhydride represented by the formula [5], which
20 comprises subjecting a tetracarboxylic acid represented by the formula [7] to
3
dehydration.
wherein R2 and n are as defined above,
wherein R2 and n are as defined above.
3. The method according to the above 1, wherein the formulae [1] and [2] are the
following formulae [1-a] and [2-a], respectively, and the formula [7] is the followin5 g
formula [7-a].
wherein R1 is a C1-5 alkyl group, R2 is a C1-5 alkyl group, and R1 and R2 may be the
same or different,
wherein R2 is a C1-5 alkyl group.
O O
O
O
O
[ 5 ] O
(R2)n
4
4. The method according to the above 2, wherein the formula [7] is the following
formula [7-a], and the formula [5] is the following formula [5-a].
wherein R2 is a C1-5 alkyl group,
wherein R2 is a C1-5 alkyl group.
5. A tetracarboxylic acid compound represented by the formula [7-a]5 :
wherein R2 is a C1-5 alkyl group.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to produce, as a useful material, a
10 cyclobutane tetracarboxylic acid and/or a dianhydride thereof simply with a high
efficiency, by using, as a raw material, a residue formed after isolation of a desired
product produced in a process for producing e.g. a cyclobutane tetracarboxylic acid
derivative.
15 DESCRIPTION OF EMBODIMENTS
[Cyclobutane tetracarboxylic acid dialkyl ester]
5
The raw material in the production method of the present invention is a compound
represented by the following formula [1] or [2], which is contained in a residue formed in
a process for producing e.g. a cyclobutane tetracarboxylic acid dialkyl ester.
wherein R1 is a C1-5 alkyl group, R2 is a C1-5 alkyl group, and n is 2 or 4. When n is 2,
R2 are preferably the same substituents, and when n is 4, all of R2 are preferably th5 e
same, but they may be different. R1 and R2 may be the same or different.
R1 is a C1-5 alkyl group, preferably a C1-3 alkyl group, and specific examples of the
alkyl group include, for example, a methyl group, an ethyl group, a normal propyl group,
an isopropyl group, a normal butyl group, a secondary butyl group, an isobutyl group, a
10 tertiary butyl group and a normal pentyl group. In a case where a polyamic acid ester
is prepared and then imidated to use it as a polyimide, R1 is preferably one having a
small number of carbon atoms and being readily detached, more preferably a methyl
group.
R2 is a C1-5 alkyl group, preferably a C1-3 alkyl group, and specific examples of the
15 alkyl group include, for example, a methyl group, an ethyl group, a normal propyl group,
an isopropyl group, a normal butyl group, a secondary butyl group, an isobutyl group, a
tertiary butyl group and a normal pentyl group.
n is an integer of from 1 to 4, preferably 2.
Specific examples of the tetracarboxylic acid dialkyl ester wherein R2 is a methyl
20 group and n is 2 in the above formula [1] or [2], will be shown in the following Table 1
and Table 2, but it should be understood that the tetracarboxylic acid dialkyl ester
applicable is by no means limited thereto.
Here, in the following Table 1 and Table 2, a1 to a4 and b1 to b4 represent the
respective positions shown in the following formula [6], and symbols in Table 1 and
25 Table 2 have the following meanings, respectively.
Me: methyl group, Et: ethyl group, Pr-n: normal propyl group, Pr-iso: isopropyl
6
group, Bu-n: normal butyl group, Bu-sec: secondary butyl group, Bu-iso: isobutyl group,
Bu-t: tertiary butyl group, Pen-n: normal pentyl group, OMe: methoxy group, OEt: ethoxy
group, OPr-n: normal propyl ether group, OPr-iso: isopropyl ether group, OBu-n: normal
butoxy group, OBu-sec: secondary butoxy group, OBu-iso: isobutoxy group, OBu-t:
tertiary butoxy group, OPen-n: normal pentyl ether grou5 p
TABLE 1
Compound a1 a2 a3 a4 b1 b2 b3 b4
(1-1) OH OMe OH OMe Me H Me H
(1-2) OH OMe OH OMe Me H H Me
(1-3) OH OMe OH OMe H Me H Me
(1-4) OH OEt OH OEt Me H Me H
(1-5) OH OEt OH OEt Me H H Me
(1-6) OH OEt OH OEt H Me H Me
(1-7) OH Opr􀊵n OH Opr􀊵n Me H Me H
(1-8) OH OPr􀊵n OH Opr􀊵n Me H H Me
(1-9) OH OPr􀊵n OH Opr􀊵n H Me H Me
(1-10) OH OPr􀊵iso OH OPr􀊵iso Me H Me H
(1-11) OH OPr􀊵iso OH OPr􀊵iso Me H H Me
(1-12) OH OPr􀊵iso OH OPr􀊵iso H Me H Me
(1-13) OH OBu􀊵n OH OBu􀊵n Me H Me H
(1-14) OH OBu􀊵n OH OBu􀊵n Me H H Me
(1-15) OH OBu􀊵n OH OBu􀊵n H Me H Me
(1-16) OH OBu􀊵sec OH OBu􀊵sec Me H Me H
(1-17) OH OBu􀊵sec OH OBu􀊵sec Me H H Me
(1-18) OH OBu􀊵sec OH OBu􀊵sec H Me H Me
(1-19) OH OBu􀊵iso OH OBu􀊵iso Me H Me H
(1-20) OH OBu􀊵iso OH OBu􀊵iso Me H H Me
(1-21) OH OBu􀊵iso OH OBu􀊵iso H Me H Me
(1-22) OH OBu􀊵t OH OBu􀊵t Me H Me H
(1-23) OH OBu􀊵t OH OBu􀊵t Me H H Me
(1-24) OH OBu􀊵t OH OBu􀊵t H Me H Me
(1-25) OH Open􀊵n OH Open􀊵n Me H Me H
(1-26) OH Open􀊵n OH Open􀊵n Me H H Me
(1-27) OH Open􀊵n OH Open􀊵n H Me H Me
7
TABLE 2
Compound a1 a2 a3 a4 b1 b2 b3 b4
(2-1) OH OMe OMe OH Me H Me H
(2-2) OH OMe OMe OH Me H H Me
(2-3) OH OMe OMe OH H Me Me H
(2-4) OH OEt OEt OH Me H Me H
(2-5) OH OEt OEt OH Me H H Me
(2-6) OH OEt OEt OH H Me Me H
(2-7) OH Opr􀊵n Opr􀊵n OH Me H Me H
(2-8) OH Opr􀊵n Opr􀊵n OH Me H H Me
(2-9) OH Opr􀊵n Opr􀊵n OH H Me Me H
(2-10) OH OPr􀊵iso OPr􀊵iso OH Me H Me H
(2-11) OH OPr􀊵iso OPr􀊵iso OH Me H H Me
(2-12) OH OPr􀊵iso OPr􀊵iso OH H Me Me H
(2-13) OH OBu􀊵sec OBu􀊵sec OH Me H Me H
(2-14) OH OBu􀊵sec OBu􀊵sec OH Me H H Me
(2-15) OH OBu􀊵sec OBu􀊵sec OH H Me Me H
(2-16) OH OBu􀊵sec OBu􀊵sec OH Me H Me H
(2-17) OH OBu􀊵sec OBu􀊵sec OH Me H H Me
(2-18) OH OBu􀊵sec OBu􀊵sec OH H Me Me H
(2-19) OH OBu􀊵iso OBu􀊵iso OH Me H Me H
(2-20) OH OBu􀊵iso OBu􀊵iso OH Me H H Me
(2-21) OH OBu􀊵iso OBu􀊵iso OH H Me Me H
(2-22) OH OBu􀊵t OBu􀊵t OH Me H Me H
(2-23) OH OBu􀊵t OBu􀊵t OH Me H H Me
(2-24) OH OBu􀊵t OBu􀊵t OH H Me Me H
(2-25) OH Open􀊵n Open􀊵n OH Me H Me H
(2-26) OH Open􀊵n Open􀊵n OH Me H H Me
(2-27) OH Open􀊵n Open􀊵n OH H Me Me H
Further, in the above formula [1] or [2], as the compound wherein n is 2, and R2 is
an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, a
secondary butyl group, an isobutyl group, a tertiary butyl group or a normal pentyl group5 ,
compounds may be exemplified wherein in the above Tables 1 and 2, each Me for b1 to
b4 is replaced by Et, Pr-n, Pr-iso, Bu-n, Bu-sec, Bu-iso, Bu-t or Pen-n.
Now, as an example for production of the raw material in the present invention, a
process for producing a cyclobutane tetracarboxylic acid dialkyl ester will be mentioned.
10 As shown by the following reaction formula, the cyclobutane tetracarboxylic acid dialkyl
ester can be produced by reacting a cyclobutane tetracarboxylic acid dianhydride [5]
with a C1-5 alcohol represented by R1OH.
8
wherein R1 is a C1-5 alkyl group, R2 is a C1-5 alkyl group, and n is 2 or 4. When n is 2,
R2 are preferably the same substituents, and when n is 4, all of R2 are preferably the
same, but they may be different. R1 and R2 may be the same or different.
The above reaction can be carried out by using, as a solvent, alcohol (R1OH)
which is also used as a reaction raw material, and other solvents may be used as th5 e
case requires. Such a solvent is not particularly limited so long as it is inert to the
reaction, and it may, for example, be a hydrocarbon such as hexane, heptane or toluene,
a halogenated hydrocarbon such as chloroform, 1,2-dichloroethane or chlorobenzene,
an ether such as diethyl ether or 1,4-dioxane, an ester such as ethyl acetate, a ketone
10 such as acetone or methyl ethyl ketone, a nitrile such as acetonitrile or propionitrile, or a
mixture thereof. It is preferably ethyl acetate or acetonitrile, more preferably
acetonitrile.
The alcohol (R1OH) is used usually in an amount of from 2 to 100 times by mole,
preferably from 2 to 40 times by mole, more preferably from 2 to 20 times by mole, to
15 the tetracarboxylic acid dianhydride [5].
The above reaction proceeds under a neutral condition, but a base or an acid may
be added.
The base may, for example, be an inorganic base such as sodium hydroxide,
potassium hydroxide, potassium carbonate or sodium hydrogencarbonate; an organic
20 base such as triethylamine, pyridine, quinoline, 8-quinolinol, 1,10-phenanthroline,
bathophenanthroline, bathocuproin, 2,2’-bipyridyl, 2-phenylpyridine, 2,6-
diphenylaminopyridine, 2-dimethylaminopyridine, 4-dimethylaminopyridine, 2-(2-
hydroxyethyl)pyridine, N,N-dimethylaniline or 1,8-azadiazabicyclo [5,4,0]-7-undene
(DBU); or a metal alkoxide such as sodium methoxide, potassium methoxide or
25 potassium t-butoxide. It is preferably sodium methoxide, potassium methoxide or
pyridine, more preferably pyridine.
The above acid may, for example, be a heteropolyacid such as phosphomolybdic
9
acid or phosphotungstic acid; an organic acid such as trimethylborate or
triphenylphosphine; an inorganic acid such as hydrochloric acid, sulfuric acid or
phosphoric acid; a hydrocarbon acid such as formic acid, acetic acid or ptoluenesulfonic
acid; or a halogenated hydrocarbon acid such as trifluoroacetic acid. It
is preferably p-toluenesulfonic acid, phosphoric acid or acetic acid, more preferably 5 ptoluenesulfonic
acid.
The base or the acid is used usually in an amount of from 0 to 100 times by mole,
preferably from 0.01 to 10 times by mole, to the tetracarboxylic acid dianhydride [5].
The reaction temperature is not particularly limited, and it may, for example, be
10 from -90 to 200 C, preferably from -30 to 100 C. The reaction time is usually from
0.05 to 200 hours, preferably from 0.5 to 100 hours.
A process for efficiently producing a compound represented by the above formula
[1-a], [2-a] or [2-b] being a specific position isomer among cyclobutane tetracarboxylic
acid dialkyl esters of the formula [1] or [2] wherein n is 2, will be described below.
15 A compound represented by the formula [1-a] or [2-a] can be produced by using a
tetracarboxylic dianhydride represented by the following formula [5-a] as the
tetracarboxylic acid dianhydride [5] in the above reaction formula.
wherein R2 is a C1-5 alkyl group.
At that time, the selectivity for the formula [1-a] will be improved as the reaction
20 temperature is low. Therefore, when it is desired to improve the reaction yield of the
formula [1-a], a more preferred reaction temperature is from 10 to 30 C. On the other
hand, in a case where it is desired to improve the reaction yield of the formula [2-a], a
more preferred reaction temperature is from 50 to 100 C.
Further, it is possible to improve the reaction rate and the selectivity for the
25 formula [1-a] also when the reaction is carried out in the presence of a base or an acid,
and it is more preferred that a basic compound is present. As the base or the acid to
be used here, the above exemplified one may be mentioned, and the preferred base or
10
acid and the preferred amount are also as mentioned above.
Further, in the present reaction, separation of the desired product formed by the
reaction is easy. For example, when the formula [5-a] is a raw material, after
completion of the reaction, the alcohol used is distilled off, and precipitated crystals are
heated and refluxed in an organic solvent, followed by cooling, whereupon precipitate5 d
crystals are collected by filtration, followed by washing and drying, whereby primary
crystals of a high purity product of the formula [1-a] can be obtained. As the organic
solvent, it is possible to use, for example, toluene, acetonitrile, ethyl acetate, an ethyl
acetate/n-heptane mixed liquid, an ethyl acetate/ alcohol mixed liquid, or an acetonitrile/
10 alcohol mixed liquid. Preferred is acetonitrile, ethyl acetate, an ethyl acetate/alcohol
mixed liquid or an acetonitrile/alcohol mixed liquid. Such alcohols may be a C1-5 lower
alcohol such as methanol, ethanol, propanol, butanol, isopropanol, etc.
The primary crystals may have the purity further improved by washing or
recrystallization. A recrystallization method may be a method wherein an organic
15 solvent is added to the primary crystals, followed by heating and then by cooling with ice,
filtration and drying. As the organic solvent, it is possible to use, for example, toluene,
acetonitrile, ethyl acetate, an ethyl acetate/n-heptane mixed liquid, an ethyl
acetate/various alcohol mixed liquid, or an acetonitrile/various alcohol mixed liquid.
Preferred is acetonitrile, ethyl acetate, an ethyl acetate/various alcohol mixed liquid or
20 an acetonitrile/various alcohol mixed liquid. Such various alcohols may be methanol,
ethanol, propanol, butanol, isopropanol, etc.
The amount of the organic solvent to be used to obtain such primary crystals, is
usually based on the weight of the desired product on the assumption that the desired
product is obtained from the raw material in a yield of 100%, and it is preferably from 2
25 to 20 times. Here, when it is desired to improve the yield, it is preferred to reduce the
amount of the organic solvent to be used, and when it is desired to obtain a high purity
product, it is preferred to increase the amount of the organic solvent to be used. In
11
consideration of such yield and purity, the amount is more preferably from 2.5 to 5 times.
On the other hand, by washing and recrystallizing the filtrate at the time of
obtaining the primary crystals, it is possible to obtain a high purity product of the formula
[2-a]. That is, the obtained filtrate is subjected to distillation to remove the solvent, and
precipitated crystals are heated and refluxed in an organic solvent, followed by cooling5 ,
whereupon precipitated crystals are collected by filtration, followed by washing and
drying, whereby the desired secondary crystals of a high purity product of the formula
[2-a] are obtainable.
As the organic solvent, it is possible to use, for example, toluene, acetonitrile,
10 ethyl acetate, an ethyl acetate/n-heptane mixed liquid, an ethyl acetate/various alcohol
mixed liquid, or an acetonitrile/various alcohol mixed liquid. Preferred is acetonitrile,
ethyl acetate, an ethyl acetate/various alcohol mixed liquid or an acetonitrile/various
alcohol mixed liquid. Such various alcohols may be methanol, ethanol, propanol,
butanol, isopropanol, etc.
15 The secondary crystals may have the purity further improved by washing or
recrystallization. A recrystallization method may be a method wherein an organic
solvent is added to the secondary crystals, followed by heating and then by cooling with
ice, filtration and drying. As the organic solvent, it is possible to use, for example,
toluene, acetonitrile, ethyl acetate, an ethyl acetate/n-heptane mixed liquid, an ethyl
20 acetate/various alcohol mixed liquid, or an acetonitrile/various alcohol mixed liquid.
Preferred is acetonitrile, ethyl acetate, an ethyl acetate/various alcohol mixed liquid or
an acetonitrile/various alcohol mixed liquid. Such various alcohols may be methanol,
ethanol, propanol, butanol, isopropanol, etc.
The amount of the organic solvent to be used when such secondary crystals are
25 obtained, is usually based on the weight obtained by subtracting the weight of primary
crystals taken out, from the weight of the desired product on the assumption that the
desired product is obtained from the starting material in a yield of 100%, and it is
preferably from 2 to 20 times. Here, when it is desired to improve the yield, it is
preferred to reduce the amount of the organic solvent to be used, and when it is desired
30 to obtain a high purity product, it is preferred to increase the amount of the organic
solvent to be used. In consideration of such yield and purity, the amount is more
preferably from 2.5 to 5 times.
12
As the above formula [5], cyclobutane tetracarboxylic acid dianhydride
represented by the following formula [5-b] may be used, and by reacting such a
compound with a C1-5 alcohol (the above mentioned R1OH), it is possible to produce a
compound represented by the formula [2-b].
wherein R2 is a C1-5 alkyl group5 .
At that time, it is possible to improve the reaction rate and the selectivity for the
formula [2-b] by carrying out the reaction in the presence of a base or an acid, more
preferably in the presence of a basic compound. As the base or acid to be used here,
the above exemplified one may be mentioned, and the preferred base or acid and the
10 preferred amount are also as mentioned above.
wherein R1 is a C1-5 alkyl group, R2 is a C1-5 alkyl group, and n is 2 or 4. When n is 2,
R2 are preferably the same substituents, and when n is 4, all of R2 are preferably the
same, but they may be different. R1 and R2 may be the same or different.
[Production of cyclobutane tetracarboxylic acid and/or dianhydride thereof from
15 compounds of formula [1] and formula [2]]
In the present invention, as shown in the following [Reaction formula 1] and
[Reaction formula 2], the compounds of the above formulae [1] and [2] which are
contained in a residue formed in a production process of e.g. a cyclobutane
tetracarboxylic acid dialkyl ester, are subjected to hydrolysis, whereby it is possible to
20 produce a cyclobutane tetracarboxylic acid [7], and further this cyclobutane
tetracarboxylic acid [7] is subjected to anhydrization, whereby it is possible to produce
cyclobutane tetracarboxylic acid and/or a dianhydride thereof.
13
wherein R1 is a C1-5 alkyl group, R2 is a C1-5 alkyl group, n is 2 or 4, and R1 and R2 may
be the same or different.
In the reaction of the above [Reaction formula 1], it is possible to obtain crystals of
a high purity cyclobutane tetracarboxylic acid [7], by distilling off a solvent in a filtrat5 e
formed as a by-product in separation of a desired product produced in e.g. an
esterification reaction, adding a carboxylic acid represented by the formula: RCO2H, an
acidic aqueous solution or a basic aqueous solution thereto, preferably heating and
refluxing, then cooling, and then correcting precipitated crystals by filtration, followed by
10 washing and drying the crystals.
The above carboxylic acid (RCO2H) is not particularly limited so long as it is in a
liquid state at a reaction temperature, but may, for example, be preferably a C1-5
aliphatic carboxylic acid such as formic acid, acetic acid or propionic acid, more
preferably formic acid. Further, an acid to be used for the acidic aqueous solution is
15 not particularly limited so long as it is soluble in water at a reaction temperature, and it
may, for example, be a heteropolyacid such as phosphomolybdic acid or
phosphotungstic acid; an inorganic acid such as hydrochloric acid, sulfuric acid or
phosphoric acid; a hydrocarbon acid such as formic acid, acetic acid or ptoluenesulfonic
acid; or a halogenated hydrocarbon acid such as trifluoroacetic acid,
20 preferably hydrochloric acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid,
formic acid or acetic acid, more preferably hydrochloric acid, sulfuric acid or ptoluenesulfonic
acid.
The amount of an acid to be used for an acidic aqueous solution is usually from
Dehydrator
[Reaction
formula 1]
[Reaction
formula 2]
14
0.01 to 100 times by mole, preferably from 0.01 to 10 times by mole to tetracarboxylic
acid diesters [1] and [2].
The amount of water to be used for an acidic aqueous solution is not particularly
limited so long as such an amount is adequate to dissolve an acid to be used at a
reaction temperature, and it is usually from 1 to 100 times by mass, preferably from 1 t5 o
10 times by mass to the acid to be used.
The base to be used for the basic aqueous solution is not particularly limited, and
it may be an alkali metal such as sodium hydroxide, potassium hydroxide, lithium
hydroxide, sodium carbonate, potassium carbonate or lithium carbonate; or an alkaline
10 earth metal such as magnesium hydroxide or calcium hydroxide. Among them, sodium
hydroxide, potassium hydroxide or lithium hydroxide may be mentioned.
The amount of a base to be used for a basic aqueous solution is usually from 0.01
to 100 times by mole, preferably from 0.01 to 10 times by mole to tetracarboxylic acid
diesters [1] and [2].
15 The amount of water to be used for a basic aqueous solution is not particularly
limited so long as such an amount is adequate to dissolve a base to be used at a
reaction temperature, but it is usually from 1 to 100 times by mass, preferably from 1 to
10 times by mass to an acid to be used.
Carboxylic acid (RCO2H), an acidic aqueous solution or a basic aqueous solution
20 is used in an amount of usually from 2 to 100 times by weight, preferably from 2 to 40
times by weight, more preferably from 2 to 6 times by weight to tetracarboxylic acid
diesters [1] and [2] in a filtrate.
Further, in the case of a reaction using the above carboxylic acid (RCO2H), the
reaction may be carried out in the presence of an acid as a catalyst. The acid is not
25 particularly limited so long as it has a relatively strong acidity. This method may be a
heteropolyacid such as phosphomolybdic acid or phosphotungstic acid; an organic acid
such as trimethylborate or triphenylphosphine; an inorganic acid such as hydrochloric
acid, sulfuric acid or phosphoric acid; a hydrocarbon acid such as formic acid, acetic
acid or p-toluenesulfonic acid; or a halogenated hydrocarbon acid such as trifluoroacetic
30 acid, preferably sulfuric acid, p-toluenesulfonic acid, phosphoric acid or acetic acid,
more preferably sulfuric acid or p-toluenesulfonic acid.
The acid is used in an amount of usually from 0 to 100 times by mole, preferably
15
from 0.01 to 10 times by mole to tetracarboxylic acid diesters [1] and [2].
The reaction temperature is not particularly limited, and it may, for example, be
from -90 to 200 C, preferably from 80 to 130 C. Further, in the case of a reaction
using a carboxylic acid (RCO2H), especially using formic acid, the reaction rate
becomes high when an alkylformate produced in a reaction system is removed from th5 e
reaction system, and therefore it is preferred to carry out the reaction at a boiling point
higher than the alkylformate produced.
The reaction time is usually from 0.05 to 200 hours, preferably from 0.5 to 100
hours.
10 On the other hand, in the reaction of the above [Reaction formula 2], cyclobutane
tetracarboxylic acid [7] obtained in [Reaction formula 1] is subjected to dehydration with
a dehydrator, whereby it is possible to obtain cyclobutane tetracarboxylic acid
dianhydride [5].
The dehydrator is not particularly limited so long as the dehydrator is in contact
15 with cyclobutane tetracarboxylic acid [7], and for example, tetracarboxylic acid [7] and
the dehydrator may be mixed in a solvent. The dehydrator is preferably a carboxylic
acid anhydride such as acetic acid anhydride, propionic acid anhydride or trifluoroacetic
acid anhydride, more preferably a lower carboxylic acid anhydride such as preferably a
C1-3 carboxylic acid anhydride, more preferably a C1-2 carboxylic acid anhydride, and
20 among them acetic acid anhydride is particularly preferred since it is economically
advantageous because of easiness of removal after anhydrization.
The amount of a dehydrator to be used is not particularly limited, and it is
preferably from 2 to 50 equivalent amount, particularly preferably from 4 to 20
equivalent amount to cyclobutane tetracarboxylic acid [7]. When it is from 2 to 50
25 equivalent amount, anhydrization is sufficiently carried out, and further the dissolved
amount of tetracarboxylic acid dianhydride [5] obtainable does not become too high,
whereby it is possible to precipitate tetracarboxylic acid dianhydride [5] in a high yield.
Further, it is not necessary to carry out anhydrization reaction in a homogenous
system by completely dissolving tetracarboxylic acid [7], and the anhydrization reaction
30 may be carried out in a heterogeneous system.
The heating temperature in the reaction is preferably from 30 to 200 C, more
preferably from 40 to 180 C, and as the reaction temperature increases, the reaction
16
rate improves. Therefore, the reaction is preferably carried out at a reflux temperature
of the solvent to be used.
Further, the reaction time may properly be determined depending upon conditions
such as the type or the temperature of the dehydrator to be used, and it is preferably
from 0.5 to 20 hours. Such a reaction time is sufficient to carry out the anhydrizatio5 n
reaction.
According to the above anhydrization reaction, it is possible to obtain a
suspension having tetracarboxylic acid dianhydride [5] suspended in a dehydrator to be
used. After the anhydrization reaction, the resulting suspension is filtrated, whereby it
10 is possible to recover a powder of tetracarboxylic acid dianhydride [5]. Further, the
above suspension may be concentrated as the case requires. Moreover, a dehydrator
is removed by e.g. drying under reduced pressure, whereby it is possible to obtain a
high-purity tetracarboxylic acid dianhydride [5] as a raw material.
Further, cyclobutane tetracarboxylic acid represented by the above formula [7]
15 obtained in the present invention is a novel compound not disclosed in documents, and
as mentioned above, it may be used for various applications such that it is possible to
easily produce cyclobutane tetracarboxylic acid dianhydride [5] therefrom.
EXAMPLES
20 Now, the present invention will be described in further detail with reference to
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.
<1H NMR analytical conditions>
Apparatus: Fourier transform superconducting NMR spectrometer (FT-NMR)
25 INOVA-400 (manufactured by Varian) 400 MHz,
Solvent: DMSO-d6,
Internal standard substance: Tetramethylsilane (TMS).
REFERENCE EXAMPLE 1: Production of cyclobutane tetracarboxylic acid dialkyl ester
17
In a nitrogen stream, into a 3 L four necked flask, 240 g (1.07 mol) of 1,3-DMCBDA
and 720 g of ethyl acetate were charged, and 8.47 g (0.107 mol) of pyridine was
added, whereupon the mixture was suspended at 25 C with stirring by a magnetic
stirrer. To this suspension, 600 g (18.73 mol, 2.5 times by weight to 1,3-DM-CBDA) of
methanol was dropwise added over a period of 1 hour so that the internal temperatur5 e
became at most 25 C. Stirring was continued for 20 minutes even after completion of
the dropwise addition, whereby a uniform reaction solution was obtained. This reaction
solution was analyzed by HPLC, whereby the HPLC relative area of compound (1-1)
was 77%, and the HPLC relative area of compound (2-1) was 22%.
10 By an evaporator, this reaction solution was distilled to remove a solvent in a
water bath of 40 C under from 170 to 140 Torr until the internal amount became 561.65
g. Then, 1,450 g of ethyl acetate was added, and the mixture was stirred and then
distilled to remove a solvent by an evaporator in a water bath of 40 C under from 170 to
140 Torr until the internal amount became 597.51 g. Thereafter, 1,450 g of ethyl
15 acetate was again added, and the mixture was stirred and then distilled to remove the
solvent by an evaporator in a water bath of 40 C under from 170 to 140 Torr until the
internal amount became 1,852 g. Further, the solvent distilled at that time was
analyzed by gas chromatography, whereby the area% of methanol was 0.3%. Then,
the remained slurry solution was heated to 80 C and refluxed for 30 minutes, and then
20 cooled at a rate of from 2 to 3 C per 10 minutes until the inner temperature became
25 C. Stirring was continued at 25 C for 30 minutes, whereupon precipitated white
crystals were collected by filtration, and the crystals were washed twice with 192.88 g of
ethyl acetate. The washed product was dried under reduced pressure to obtain 223.77
g of white crystals. From the 1H NMR analytical results, the crystals were confirmed to
25 be compound (1-1) (HPLC relative area: 99.0%) (yield: 72.5%).
Production of (7-1) by hydrolysis of dicarboxylic acid diester
Into a 1L four necked flask, a solution obtained by mixing a filtrate obtained by
Formic acid,
Sulfuric acid
18
filtration at the time of collecting the crystal of (1-1) and a washing liquid of the crystal, in
Reference Example 1, were charged, then the solution was distilled at 40 C to remove a
solvent until a total weight would be 170 g, and 424 g of formic acid with a purity of 88%
was added to the solution which was then distilled to remove a solvent until a total
weight would be 340 g. To such a solution, 29.5 g of sulfuric acid was added, followe5 d
by stirring under heating at 102 C. 75 g of an initial solvent distilled at that time was
removed, and further heated and refluxed at 110 C for 20 hours. Further, under the
following HPLC conditions, it was confirmed that the peak area% became at most 0.5%
at a retention time of 6.3 minutes, and a reaction fluid was cooled until the internal
10 temperature would be 23 C.
Thereafter, stirring was carried out at a temperature of from 20 to 25 C for 1 hour,
then a crystal precipitated was filtrated, and a crystal obtained was washed twice with
42.4 g of formic acid with a purity of 88% to obtain 97.3 g of crude crystals (wet product)
of (7-1). Further, 425 g of ethyl acetate was added to 97.3 g of such crude crystals,
15 and a resulting slurry was stirred at an internal temperature of 25 C for 1 hour, then
crystals obtained were filtrated and washed twice with 42.5 g of ethyl acetate, and then
white crystals obtained were dried under reduced pressure to obtain 72.01 g (yield:
94.0%) of (7-1).
From the 1H NMR analytical results, the crystals were confirmed to be (7-1).
20 1H NMR ( DMSO-d6, ppm ) : 12.49 ( s, 2H ), 3.29( s, 2H ), 1.42 ( s, 6H ).
HPLC (high peformance liquid chromatography) analysis employed in this
measurement was carried out under the following conditions.
Conditions for HPLC analysis;
Columne: Atlantis cd18 (Waters), 5 µm, 4.6×250 mm, oven: 40 C
25 Eluent: acetonitirle/0.5% phosphoric acid aqueous solution=16/84, detection
wavelength: 211 nm
Flow rate: 1.0 mL/min, amount of sample injected: 10 µL, concentration of sample: 1
wt%
Production of tetracarboxylic acid anhydride (5-1)
19
In a nitrogen stream, into a 500 mL four necked flask, 70 g of tetracarboxylic acid
(7-1) obtained in Example 1-1 and 350 g of acetic acid anhydride were charged and
suspended at 25 C with stirring by a magnetic stirrer, and then heated (130 C) and
refluxed for 4 hours. Thereafter, the internal temperature was cooled to at most 25 5 C,
followed by stirring at a temperature of at most 25 C for 1 hour. Thereafter precipitated
white crystals were collected by filtration, and the crystals were washed twice with 32 g
of dehydrated acetonitrile, and the resulting white crystals were dried under reduced
pressure to obtain 57.5 g (yield: 95%) of (5-1).
10 From the 1H NMR analytical results, the crystals were confirmed to be (5-1).
1H NMR ( DMSO-d6, ppm ) : 3.89 ( s, 2H ), 1.38 ( s, 6H ).
INDUSTRIAL APLICABILITY
According to the production method of the present invention, it is possible to
15 obtain cyclobutane tetracarboxylic acid and/or a dianhydride thereof from, as a raw
material, a residue formed after separation of a desired product produced in a process
for producing e.g. cyclobutane tetracarboxylic acid derivative, and therefore such a
production method can be used in various fields.
20 The entire disclosure of Japanese Patent Application No. 2014-007188 filed on
January 17, 2014 including specification, claims, drawings and summary is incorporated
herein by reference in its entirety.
Acetic acid
anhydride
20

CLAIMS
1. A method for producing a tetracarboxylic acid represented by the formula [7],
which comprises subjecting a mixture of a tetracarboxylic acid dialkyl ester represented
by the formula [1] and a tetracarboxylic acid dialkyl ester represented by the formula [2],
to hydrolysis, in a solvent5 .
wherein R1 is a C1-5 alkyl group, R2 is a C1-5 alkyl group, n is 2 or 4, and R1 and R2 may
be the same or different,
wherein R2 and n are as defined above.
2. The method according to Claim 1, wherein the hydrolysis is carried out by reacting
10 the mixture with an organic carboxylic acid of the formula: RCOOH (wherein R is
hydrogen or a C1-10 alkyl.)
3. The method according to Claim 1 or 2, wherein the hydrolysis is carried out in the
presence of an acid catalyst.
4. The method according to any one of Claims 1 to 3, wherein the solvent is an
15 organic solvent selected from the group consisting of a hydrocarbon, a halogenated
hydrocarbon, an ester, a ketone and a nitrile.
5. A method for producing an acid dianhydride represented by the formula [5], which
comprises subjecting a tetracarboxylic acid represented by the formula [7] to
dehydration.
21
wherein R2 is a C1-5 alkyl group, and n is 2 or 4,
wherein R2 and n are as defined above.
6. The method according to Claim 5, wherein the dehydration is carried out by
heating to a temperature of from 40 to 160 C, in the presence of a dehydrator.
7. The method according to Claim 5, wherein the dehydrator is a C1-3 lowe5 r
carboxylic anhydride.
8. The method according to Claim 1, wherein the formulae [1] and [2] are the
following formulae [1-a] and [2-a], respectively, and the formula [7] is the following
formula [7-a].
10 wherein R1 is a C1-5 alkyl group, R2 is a C1-5 alkyl group, and R1 and R2 may be the
same or different,