JP2015137234A - Method for producing carboxylic acid anhydride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a carboxylic acid anhydride, which enables a carboxylic acid anhydride to be produced efficiently while sufficiently reducing a used amount of a carboxylic acid having 1 to 5 carbons.SOLUTION: Provided is a method for producing a carboxylic acid anhydride by heating a mixture of a raw material compound represented by the formula (1) and a carboxylic acid having 1 to 5 carbons and removing distillate components, comprising before removing the distillate components the steps of: separating the carboxylic acid having 1 to 5 carbon atoms from a vapor generated from the mixture by the heating; and supplying the carboxylic acid having 1 to 5 carbon atoms obtained by the separation step to the mixture.

Description

  The present invention relates to a method for producing a carboxylic acid anhydride.

  Carboxylic anhydride is used as a raw material for polyimide, polyester, polyamide and the like, a curing agent for thermosetting resin, and the like. Various methods are known as a method for producing such a carboxylic acid anhydride. For example, in JP-A-5-140141 (Patent Document 1), the following general formula (A):

[In General Formula (A), R ^a is a divalent to tetravalent organic group, Z ¹ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a —COOR ^d group, and Z ² is a hydrogen atom, carbon An alkyl group having 1 to 6 carbon atoms or a —COOR ^e group, wherein R ^{b to} R ^e may be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; ]
A method for producing a carboxylic acid anhydride is disclosed in which a compound represented by the formula (carboxylic acid or carboxylic acid ester) is heated in a lower carboxylic acid and the vapor is distilled off to obtain a carboxylic acid anhydride. In such Patent Document 1, when a carboxylic acid ester is used as a raw material compound by the method for producing a carboxylic acid anhydride, a carboxylic acid decomposition reaction of an ester group in the carboxylic acid ester and a subsequent acid It is disclosed that two reactions such as an anhydration reaction can be performed together in one step. However, when the conventional method for producing a carboxylic acid anhydride as described in Patent Document 1 is used, it is necessary to use a large amount of a lower carboxylic acid when preparing the carboxylic acid anhydride.

Japanese Patent Laid-Open No. 5-140141

  This invention is made | formed in view of the subject which the said prior art has, and makes it possible to reduce the usage-amount of C1-C5 carboxylic acid sufficiently, and to manufacture a carboxylic anhydride efficiently. It aims at providing the manufacturing method of a carboxylic anhydride.

  As a result of intensive studies to achieve the above object, the present inventors heated a mixed liquid containing a raw material compound represented by the following general formula (1) and a carboxylic acid having 1 to 5 carbon atoms, In the method for producing a carboxylic acid anhydride, the carboxylic acid anhydride is obtained by removing the distillate component, and before removing the distillate component, carbon atoms having 1 to The amount of the carboxylic acid having 1 to 5 carbon atoms is reduced by including the step of separating the carboxylic acid having 5 and the step of supplying the carboxylic acid having 1 to 5 carbon atoms obtained by the separating step to the mixed solution. It has been found that the carboxylic acid anhydride can be efficiently produced with a sufficient reduction, and the present invention has been completed.

  That is, the method for producing a carboxylic acid anhydride of the present invention has the following general formula (1):

[In Formula (1), R ¹ is a tetravalent organic group having at least two adjacent carbon atoms, and the groups represented by the formulas: —COOR ² and —COOR ³ are present on the two adjacent carbon atoms. Each is connected,
R ² and R ³ may be the same or different and are each a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or carbon. 1 type selected from the group consisting of an aryl group having 6 to 20 carbon atoms and an aralkyl group having 7 to 20 carbon atoms,
X is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and the formula: -COOR ^{4 (R 4} has the same meaning as the ^{R 2,} be the same or different and ^{R 2} 1 type selected from the group consisting of groups represented by:
Y represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and the formula: -COOR ^{5 (R 5} has the same meaning as the ^{R 2,} be the same or different and ^{R 2} 1 type selected from the group consisting of groups represented by: ]
A method for producing a carboxylic acid anhydride by heating a mixed solution containing a raw material compound represented by the formula (1) and a carboxylic acid having 1 to 5 carbon atoms and removing a distillate component,
Separating the carboxylic acid having 1 to 5 carbon atoms from the vapor generated from the mixed solution by the heating before removing the distillate component;
And a step of supplying the mixed liquid with a carboxylic acid having 1 to 5 carbon atoms obtained by the separation step.

  In the method for producing a carboxylic acid anhydride of the present invention, the step of separating the carboxylic acid having 1 to 5 carbon atoms may be a step of separating the carboxylic acid having 1 to 5 carbon atoms by fractional distillation. preferable.

  In the method for producing a carboxylic acid anhydride of the present invention, it is preferable to use a rectifying column in the separation step of the carboxylic acid having 1 to 5 carbon atoms.

  Moreover, in the manufacturing method of the carboxylic acid anhydride of the said invention, it is preferable that the pressure conditions at the time of heating the said liquid mixture are 0.001-1.0 Mpa.

  Moreover, in the manufacturing method of the said carboxylic acid anhydride of this invention, it is preferable that the temperature conditions at the time of heating the said liquid mixture are 30-300 degreeC.

  Furthermore, in the method for producing a carboxylic acid anhydride of the present invention, the raw material compound is represented by the following general formula (2):

Wherein ^{(2), R 2, R} 3, R 4, R 5 has the same meaning as ^{R 2, R 3, R 4} , R 5 described in the above general formula ^{(1), R 6, R} 7, R ⁸ may be the same or different and each represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms and a fluorine atom, and n represents an integer of 0 to 12 . ]
It is preferable that it is a spiro compound represented by these.

  The reason why the above-described object is achieved by the method for producing a carboxylic acid anhydride of the present invention is not necessarily clear, but the present inventors speculate as follows. Here, first, a conventional method for producing a carboxylic acid anhydride as described in Patent Document 1 will be described with reference to the case of producing a carboxylic acid anhydride using a tetramethyl ester of tetracarboxylic acid. In the conventional method for producing a carboxylic acid anhydride, when the tetramethyl ester of tetracarboxylic acid is heated in a lower carboxylic acid, a carboxylic acid anhydride is produced and a methyl ester of the lower carboxylic acid and water are by-produced. (For example, when the lower carboxylic acid is acetic acid, the methyl ester of the lower carboxylic acid is methyl acetate). Here, a reaction (A) in which a carboxylic acid anhydride, a methyl ester of a lower carboxylic acid and water are produced from the raw material compound and a lower carboxylic acid, and a methyl ester of the carboxylic acid anhydride and a lower carboxylic acid; It is known that the reaction (B) in which the raw material compound and the lower carboxylic acid are produced from water is an equilibrium reaction. Therefore, the more the methyl ester of lower carboxylic acid by-produced by heating the mixed solution and water remain in the reaction system, the more difficult it is to advance the reaction efficiently. From this point of view, in order to allow the reaction (A) to proceed efficiently, conventionally, when the carboxylic acid anhydride is produced, by-products such as water and methyl esters of lower carboxylic acids are not distilled. The step of removing (the step of removing the distillate component) has been carried out (note that the present inventors have found that the removal of the distillate component (for example, distillation) is the rate-limiting step of the reaction or deeply in the rate-limiting step). I guess it is involved.) The removal of the distillate component containing water, esters of lower carboxylic acids, etc. is generally performed by distilling off the vapor generated during heating. When the distillate component is removed in this manner, a large amount of the lower carboxylic acid used as the reaction component and the solvent in the reaction (A) is removed together with the by-product. Therefore, conventionally, while removing the distillate component, a large amount of new lower carboxylic acid was added to the mixed solution to advance the reaction (A) (paragraphs [0054] to [0055] of Patent Document 1 above). reference). In view of such a situation, the present inventors have made extensive studies, and in the conventional method for producing a carboxylic acid anhydride described in Patent Document 1, the reaction (A) sufficiently proceeds. Therefore, since a large amount of new lower carboxylic acid was added to the mixed solution, the cost increased, and it was found difficult to apply industrially. As a result of further earnest research based on such knowledge, the mixture is heated using the above-described mixed solution according to the present invention, and the mixture is heated before the distillate component is removed. The carboxylic acid having 1 to 5 carbon atoms is separated from the vapor generated from the mixed solution, and the carboxylic acid having 1 to 5 carbon atoms obtained by such a separation step is supplied to the mixed solution and is contained again. This makes it possible to remove distillate components (by-products, etc.) from the reaction system, while the carboxylic acid having 1 to 5 carbon atoms is directly removed as a distillate component together with other components. It was found that the amount of carboxylic acid having 1 to 5 carbon atoms can be sufficiently reduced throughout the reaction, and the carboxylic acid anhydride can be produced more efficiently. As described above, in the present invention, the carboxylic acid having 1 to 5 carbon atoms is separated and extracted from the vapor generated from the mixed solution by heating, and the carboxylic acid having 1 to 5 carbon atoms is reused. The amount of slag out of the reaction system is sufficiently reduced and the amount of carboxylic acid having 1 to 5 carbon atoms to be newly used can be sufficiently reduced. The present inventors infer that the product can be manufactured well. Thus, since the manufacturing method of the carboxylic acid anhydride of this invention is a method advantageous in terms of cost, it is especially useful for manufacture of industrial carboxylic acid anhydride.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the manufacturing method of carboxylic acid anhydride which makes it possible to manufacture carboxylic acid anhydride efficiently, fully reducing the usage-amount of C1-C5 carboxylic acid. It becomes.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

The method for producing a carboxylic acid anhydride of the present invention comprises heating a mixed liquid containing the raw material compound represented by the above general formula (1) and a carboxylic acid having 1 to 5 carbon atoms to remove a distillate component. A method for producing a carboxylic acid anhydride to obtain a carboxylic acid anhydride, comprising:
Separating the carboxylic acid having 1 to 5 carbon atoms from the vapor generated from the mixed solution by the heating before removing the distillate component;
And a step of supplying the mixed liquid with a carboxylic acid having 1 to 5 carbon atoms obtained by the separation step.

  Here, first, the raw material compound, the carboxylic acid having 1 to 5 carbon atoms, and the mixed solution used in such a method for producing a carboxylic acid anhydride will be described.

(Raw compound)
The raw material compound according to the present invention has the following general formula (1):

(A carboxylic acid compound or a carboxylic acid ester compound).

R ¹ in the general formula (1) is a tetravalent organic group having at least two adjacent carbon atoms, and the two adjacent carbon atoms are represented by the formulas: —COOR ² and —COOR ³ . Groups to which each group is attached. Thus, R ¹ is a tetravalent organic group having at least two adjacent carbon atoms. That is, R ¹ is a tetravalent organic group having at least two adjacent carbon atoms and having four bonds for bonding to a group represented by the formula: X, Y, COOR ² , COOR ^3. For example, a tetravalent chain saturated hydrocarbon group which may have a hetero atom, or a tetravalent cyclic saturated hydrocarbon which may have a hetero atom. Group, a tetravalent unsaturated hydrocarbon group which may have a hetero atom, a tetravalent unsaturated hydrocarbon group which may have a hetero atom, and the like. Examples of such R ¹ include the following general formulas (101) to (115):

[In formulas (101) to (115), * 1 represents a bond that binds to COOR ² in formula (1), * 2 represents a bond that binds to COOR ³ in formula (1), and * 3 represents a bond bonded to X in Formula (1), * 4 represents a bond bonded to Y in Formula (1), and R ⁶ , R ⁷ , and R ⁸ are each independently hydrogen 1 type selected from the group which consists of an atom, a C1-C10 alkyl group, and a fluorine atom is shown, n shows the integer of 0-12, m shows the integer of 0-5. ]
An organic group represented by may be suitably used.

Carbon number of the alkyl group which can be selected as R < ⁶ > in such general formula (101)-(115) is 1-10. When the carbon number of such an alkyl group exceeds the upper limit, production and purification tend to be difficult. Moreover, as carbon number of the alkyl group which can be selected as such R < ⁶ >, it is preferable that it is 1-5 from a viewpoint of the ease of manufacture and refinement | purification, and it is more preferable that it is 1-3. Such an alkyl group that can be selected as R ⁶ may be linear or branched. In addition, R ⁶ in the general formulas (101) to (115) is more preferably independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms from the viewpoint of ease of production and purification. Among these, from the viewpoint of easy availability of raw materials and easier purification, each independently is more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. Particularly preferred is an atom or a methyl group. Moreover, it is especially preferable that several R < ⁶ > in such a formula is the same from viewpoints, such as ease of manufacture and refinement | purification.

Moreover, the C1-C10 alkyl group which can be selected as R < ⁷ >, R < ⁸ > in such general formula (101)-(115) is the C1-C10 alkyl group which can be selected as R < ⁶ >. It is the same thing. As such substituents that can be selected as R ⁷ and R ⁸ , from the viewpoint of ease of production and purification of the raw material compound, among the above substituents, a hydrogen atom, a carbon number of 1 to 10 (more preferably 1 to 5, more preferably 1 to 3) of an alkyl group, and particularly preferably a hydrogen atom or a methyl group.

  Moreover, n in said general formula (101)-(115) shows the integer of 0-12. When the value of n exceeds the upper limit, it is difficult to purify the raw material compounds represented by the general formulas (101) to (115). In addition, the upper limit of the numerical value range of n in the general formulas (101) to (115) is more preferably 5 from the viewpoint that the purification of the raw material compound becomes easier. Is particularly preferred. Further, the lower limit of the numerical value range of n in the general formulas (101) to (115) is more preferably 1 and particularly preferably 2 from the viewpoint of the stability of the raw material. Thus, as n in the general formulas (101) to (115), an integer of 2 to 3 is particularly preferable.

  Furthermore, m in the general formulas (106) to (111) represents an integer of 0 to 5. When the value of m exceeds the upper limit, it becomes difficult to produce and purify the compounds represented by the general formulas (106) to (111). Further, the upper limit of the numerical value range of m in the general formulas (106) to (111) is more preferably 3 and particularly preferably 1 from the viewpoint of ease of production and purification. . In addition, the lower limit of the numerical range of m in the general formulas (106) to (111) is particularly preferably 0 from the viewpoint of ease of production and purification. Thus, m in the general formulas (106) to (111) is particularly preferably an integer of 0 to 1.

In the compound represented by the general formula (1), R ² and R ³ may be the same or different, and each is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or 3 to 10 carbon atoms. 1 type selected from the group consisting of a cycloalkyl group, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms and an aralkyl group having 7 to 20 carbon atoms.

The alkyl group that can be selected as R ² and R ³ in the general formula (1) is an alkyl group having 1 to 10 carbon atoms. When the carbon number of such an alkyl group exceeds 10, purification becomes difficult. Moreover, as carbon number of the alkyl group which can be selected as such R < ² >, R < ³ >, from a viewpoint that refinement | purification becomes easier, it is more preferable that it is 1-5, and it is further 1-3. preferable. Further, such an alkyl group that can be selected as R ² and R ³ may be linear or branched.

Further, a cycloalkyl group which may be selected as R ^2, R ³ in the general formula (1) is a cycloalkyl group having a carbon number of 3-10. If the number of carbon atoms in such a cycloalkyl group exceeds 10, purification becomes difficult. Furthermore, it as the number of carbon atoms in such R ^2, R ³ cycloalkyl group which may be selected as, from the viewpoint of purification becomes easier, more preferably from 3 to 8, 5 to 6 Further preferred.

Furthermore, the alkenyl group that can be selected as R ² or R ³ in the general formula (1) is an alkenyl group having 2 to 10 carbon atoms. When the carbon number of such an alkenyl group exceeds 10, purification becomes difficult. The number of carbon atoms of the alkenyl group that can be selected as R ² or R ³ is more preferably 2 to 5 and further preferably 2 to 3 from the viewpoint of easier purification. preferable.

Also, an aryl group which may be selected as ^R 2, ^{R 3} in the general formula (1) is an aryl group having 6 to 20 carbon atoms. If the number of carbon atoms in such an aryl group exceeds 20, purification becomes difficult. Moreover, as carbon number of the aryl group which can be selected as such R < ² >, R < ³ >, from a viewpoint that refinement | purification becomes easier, it is more preferable that it is 6-10, and it is further 6-8. preferable.

The aralkyl group that can be selected as R ² or R ³ in the general formula (1) is an aralkyl group having 7 to 20 carbon atoms. If the number of carbon atoms in such an aralkyl group exceeds 20, purification becomes difficult. In addition, the number of carbon atoms of the aralkyl group that can be selected as R ² or R ³ is more preferably 7 to 10 and further preferably 7 to 9 from the viewpoint of easier purification. preferable.

Furthermore, R ² and R ³ in the general formula (1) are each independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, n, from the viewpoint of easier purification. A butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, a 2-ethylhexyl group, a cyclohexyl group, an allyl group, a phenyl group, or a benzyl group is preferable, and a methyl group is particularly preferable. In addition, although R < ² >, R < ³ > in the said General formula (1) may be the same or different, it is more preferable that it is the same from a synthetic viewpoint.

In the compound represented by the general formula (1), the groups represented by the formulas: —COOR ² and —COOR ³ must be bonded to two adjacent carbon atoms in the tetravalent organic group, respectively. There is. That is, when the case where R ¹ is an organic group represented by the general formulas (101) to (115) is described as an example, the raw material compound has each bond (B) bonded to adjacent carbon in each organic group ( For example, a group represented by the formula: COOR ² and a group represented by the formula: COOR ³ are bonded to * 1 and * 2), respectively. Thus, as the raw material compound, it is necessary to use a compound in which groups represented by the formulas: —COOR ² and —COOR ³ are introduced into two adjacent carbon atoms, respectively. It becomes possible to form.

Further, X in the general formula (1) is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and the formula: -COOR ^{4 (R 4} has the same meaning as the ^{R 2} , R ² may be the same as or different from R ² )).

  When the carbon number of the alkyl group that can be selected as X in the general formula (1) exceeds the above upper limit, production and purification tend to be difficult. Moreover, as carbon number of the alkyl group which can be selected as such X, it is preferable that it is 1-6 from a viewpoint of the ease of manufacture and refinement | purification, and it is more preferable that it is 1-4. Further, such an alkyl group that can be selected as X may be linear or branched.

  Moreover, when the carbon number of the alkenyl group that can be selected as X in the general formula (1) exceeds the upper limit, production and purification tend to be difficult. Moreover, as carbon number of the alkenyl group which can be selected as such X, it is preferable that it is 2-6 from a viewpoint of the ease of manufacture and refinement | purification, and it is more preferable that it is 2-4. Further, such an alkenyl group that can be selected as X may be linear or branched.

In the group represented by the formula: —COOR ⁴ that can be selected as X in the general formula (1), R ⁴ is the same as R ² (hydrogen atom, alkyl group having 1 to 10 carbon atoms, A cycloalkyl group having 3 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms). The preferred one is the same as R ² described above.

  Such X is more preferably a group represented by the formula: -COOMe or -COOEt.

Further, Y in the general formula (1) is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and the formula: -COOR ^{5 (R 5} has the same meaning as the ^{R 2} , R ² may be the same as or different from R ² )). Such an alkyl group having 1 to 10 carbon atoms and an alkenyl group having 2 to 10 carbon atoms that can be selected as Y in the formula (1) are the same as those described above for X. In the group represented by the formula: —COOR ⁵ that can be selected as Y in the general formula (1), the R ⁵ is the same as the R ^2, and the preferred one is the same as the R ^2. belongs to. Such Y is more preferably a group represented by the formula: -COOMe or -COOEt.

Moreover, in the raw material compound represented by the general formula (1), when the group represented by the formula: —COOR ⁴ and / or —COOR ⁵ is included, R ² , R ³ , R ⁴ , and R ⁵ are the same. Although they may be different from each other, they are preferably the same from the viewpoint of synthesis of the raw material compounds.

In the raw material compound represented by the general formula (1), X and Y are groups represented by the formulas: —COOR ⁴ and —COOR ⁵ from the viewpoint of ease of production and purification, respectively. It is preferable. Thus, the raw material compound represented by the general formula (1) is preferably a tetracarboxylic acid compound or a tetracarboxylic acid ester compound. Thus, when the raw material compound represented by the general formula (1) is a tetracarboxylic acid compound or a tetracarboxylic acid ester compound, examples of such a compound include the following general formulas (1-20) to (1 -26):

^{Wherein, R 2, R 3, R} 4, R 5 has the same meaning as ^{R 2, R 3, R 4} , R 5 described in the above general formula (1). ]
And the like (a compound in which X in the formula (1) is a group represented by the formula: -COOR ⁴ and Y is a group represented by the formula: -COOR ⁵ ), and the like.

  Moreover, as such a raw material compound represented by the general formula (1), a carboxylic acid anhydride that can be suitably used as a material (monomer) for forming a polyimide having excellent heat resistance and a sufficiently low linear expansion coefficient From the viewpoint that can be produced, the following general formula (2):

Wherein ^{(2), R 2, R} 3, R 4, R 5 has the same meaning as ^{R 2, R 3, R 4} , R 5 described in the above general formula (1) (same as the preferred R ⁶ , R ⁷ and R ⁸ may be the same or different, and each is selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms and a fluorine atom. N represents an integer of 0 to 12. ]
A spiro compound represented by the formula is preferred. Incidentally, ^{R 6,} R 7, ^{R 8} in the general formula (2) is the same as the ^{R 6,} R 7, ^{R 8} in the general formula (101) to (115), those that suitable Is the same. Moreover, n in the said General formula (2) is synonymous with n in the said General formula (101)-(115), The suitable thing is also the same.

  In addition, the method for preparing such a raw material compound is not particularly limited, and a known method can be appropriately used. For example, as the raw material compound, a compound represented by the general formula (2) (spiro In the case of using a compound), a method for preparing a spiro compound disclosed in International Publication No. 2011/099518 may be appropriately used.

(C1-C5 carboxylic acid)
The carboxylic acid used in the present invention is a carboxylic acid having 1 to 5 carbon atoms (hereinafter sometimes simply referred to as “lower carboxylic acid”). When the carbon number of such a lower carboxylic acid exceeds the upper limit, production and purification become difficult. Such a lower carboxylic acid can function not only as a solvent but also as a reaction component when the raw material compound is a carboxylic acid ester compound.

  Examples of such lower carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, and the like. Among these lower carboxylic acids, formic acid, acetic acid and propionic acid are preferable, formic acid and acetic acid are more preferable, and acetic acid is particularly preferable from the viewpoint of ease of production and purification. Such lower carboxylic acids may be used singly or in combination of two or more.

(Mixture)
The liquid mixture concerning this invention contains the said raw material compound and the said C1-C5 carboxylic acid (lower carboxylic acid).

  In such a mixed solution, the content of the raw material compound represented by the general formula (1) is preferably 1 to 40% by mass and more preferably 2 to 30% by mass in the lower carboxylic acid. preferable. If the content of the raw material compound is less than the lower limit, the yield tends to decrease. On the other hand, if the content exceeds the upper limit, the reaction rate tends to decrease.

  In addition, the content of such a lower carboxylic acid (for example, formic acid, acetic acid, propionic acid) is not particularly limited, but it is 2 to 500 times mol with respect to the raw material compound represented by the general formula (1). It is preferably 4 to 200 times mol. When the content of such a lower carboxylic acid (formic acid, acetic acid, propionic acid, etc.) is less than the lower limit, the reaction rate tends to decrease. On the other hand, when the content exceeds the upper limit, the yield tends to decrease.

  In addition, when the carboxylic acid and the lower carboxylic acid are reacted, the reaction can be carried out without using a catalyst depending on the reaction conditions (temperature conditions, etc.) employed. The presence or absence is not particularly limited, but it is more preferable to use a catalyst because the reaction rate can be further improved to reduce the time required for the reaction and the product can be obtained more efficiently. From such a viewpoint, the mixed solution preferably contains a catalyst.

  As such a catalyst, any of a homogeneous catalyst and a heterogeneous catalyst can be used, and is not particularly limited. Among them, an acidic catalyst (more preferably has a relatively strong acid strength). Catalyst), for example, mineral acids such as sulfuric acid, hydrochloric acid, hydrofluoric acid and fluorosulfuric acid; heteropolyacids such as phosphomolybdic acid, phosphotungstic acid, silicomolybdic acid and silicotungstic acid; methanesulfonic acid and benzenesulfonic acid Organic sulfonic acids such as toluenesulfonic acid and naphthalenesulfonic acid; halogenated acetic acid such as chloroacetic acid, trichloroacetic acid, fluoroacetic acid and trifluoroacetic acid; solid acid catalyst such as ion exchange resin, metal oxide, zeolite and metal complex; Etc. can be used as appropriate. The amount of such a catalyst used varies depending on the type of the catalyst and cannot be generally specified, but the mass ratio to the lower carboxylic acid ([catalyst] / [lower carboxylic acid]) is 0.0001 to 1. 0.0 is preferable, and 0.001 to 0.5 is more preferable.

  Among these catalysts, it is preferable to use a heterogeneous catalyst because the catalyst and the carboxylic acid anhydride crystals can be efficiently separated after the production of the carboxylic acid anhydride. The heterogeneous catalyst is not particularly limited, but the above-described solid acid catalyst (ion exchange resin, metal oxide, zeolite, metal complex, etc.) can be suitably used, and in particular, from the viewpoint of acid strength, ion exchange Resins (amberlist, amberlite, etc.) are more preferred. Such heterogeneous catalysts may be used singly or in combination of two or more. Such heterogeneous catalysts are commercially available products (for example, ion exchange resins manufactured by Organo Corporation: trade names “Amberlist 15”, “Amberlist 35”, “Amberlite 200C”, “Amberlite 200CT”, etc.) May be used as appropriate.

  Moreover, as such a heterogeneous catalyst, it is possible to improve the contact property with respect to the raw material compound, and therefore it is preferable to use a particulate catalyst. As such a particulate heterogeneous catalyst, those having an average particle diameter of 0.3 to 1.0 mm are preferably used, and those having an average particle diameter of 0.6 to 0.8 mm should be used. Is more preferable. When the average particle size is less than the lower limit, when the catalyst is contained in a container (for example, a bag) as described later, the catalyst flows out into the reaction solution, and the effect obtained by using the container is obtained. On the other hand, if the upper limit is exceeded, the specific surface area of the catalyst tends to be small, and the reaction time tends to be long.

  Furthermore, such a heterogeneous catalyst is made of a porous cloth because it can more efficiently separate the heterogeneous catalyst and the carboxylic acid anhydride crystals after the production of the carboxylic acid anhydride. It is preferable to accommodate and use in a container for accommodating the catalyst. Such a porous cloth is sufficient so that the component of the cloth is not dissolved into the reaction system when heated by the lower carboxylic acid or melted into the reaction system by heat and the container shape is not deformed. What consists of material which has heat resistance and acid resistance is preferable. When a material that does not have sufficient heat resistance is used, the container is easily deformed or deteriorated by heating in the process of obtaining the carboxylic anhydride, and as a result, the heterogeneous catalyst flows out of the container. The separation of the catalyst and the product cannot be performed more efficiently, or the by-product is formed by the reaction between the molten component of the material forming the container and the raw material compound. It tends to be impossible to produce carboxylic acid anhydrides efficiently. In addition, when using a material that does not have sufficient acid resistance, the components of the container are dissolved in the step of obtaining the carboxylic anhydride, and as a result, the heterogeneous catalyst flows out of the container, Even if a container is used, it becomes impossible to efficiently separate the catalyst and the product, and further, a by-product is formed by the reaction between the eluted component and the raw material compound, and the target carboxylic acid is formed. There is a tendency that the anhydride cannot be produced efficiently.

  In addition, a specific material for forming such a porous cloth is not particularly limited, and may be a resin material or an inorganic material (for example, glass fiber, silica fiber, etc.). The material for forming such a porous cloth is preferably a resin material, more preferably polyphenylene sulfide or polytetrafluoroethylene, from the viewpoint of the degree of freedom in design when processing into a container. Polyphenylene sulfide is particularly preferred. Moreover, the hole formed in such a porous cloth should just have a magnitude | size which a heterogeneous catalyst does not flow out of a container, and according to the magnitude | size of the heterogeneous catalyst to be used, The size of the hole can be changed as appropriate. Such a porous cloth is not particularly limited, and is a woven cloth formed by weaving a thread-like material, a non-woven cloth made of a fibrous material, or a cloth in which holes are formed by a needle punch or the like in a non-woven cloth or a resin sheet. It is also possible to appropriately use a cloth in which holes are formed so that the heterogeneous catalyst and the reactant can be contacted in acetic acid.

  As such a porous cloth, a cloth manufactured by a known method may be appropriately used. Moreover, as such a porous cloth, a commercially available product may be used. For example, a commercially available filter cloth (for example, trade names “PS9A” or “PS10DN2” manufactured by Nakao Filter Industry Co., Ltd.) or a commercially available filter cloth may be used. A mesh cloth (for example, trade names “PPSP50” and “PPSP60” manufactured by NBC Meshtec, trade name “NET”, etc., manufactured by Gunze Co., Ltd.) may be used as appropriate.

  In addition, the shape of the container for accommodating the catalyst made of such a porous cloth is not particularly limited as long as it is a shape capable of accommodating the heterogeneous catalyst. It may be a box or a box, and it is preferable to use a bag. In addition, the specific shape of such a container may be, for example, a bag shape such as a spherical shape, an elliptical spherical shape, an envelope shape, and a regular octahedron shape (tea bag type). Further, a container for containing such a catalyst may be provided with a small chamber by the porous cloth in the container in order to prevent the catalysts from aggregating with each other in the container. In addition, according to the shape, size, etc. of the reactor used for the reaction, only one container for accommodating the catalyst may be used, or a plurality of containers may be used.

  In the case of using the heterogeneous catalyst, the content of the heterogeneous catalyst is not particularly limited, but with respect to the content (molar amount) of the raw material compound represented by the general formula (1), The amount of the heterogeneous catalyst (for example, solid acid catalyst) is preferably 30 to 70 mol% (0.3 to 0.7 times mol), preferably 40 to 60 mol% (0. More preferably, the amount is 4 to 0.6 times mole). If the content of such a heterogeneous catalyst is less than the lower limit, the reaction rate tends to decrease. On the other hand, even if the upper limit is exceeded, the effect obtained by using the catalyst can be further improved. On the other hand, the economy tends to decline. Here, the molar amount of the heterogeneous catalyst is a molar amount in terms of a functional group (for example, sulfonic acid group (sulfo group), etc.) in the ion exchange resin when the heterogeneous catalyst is an ion exchange resin. In addition, when the heterogeneous catalyst is an acid catalyst made of a metal oxide or a metal complex, it is a molar amount in terms of protons in the catalyst. In the mixed solution, the heterogeneous catalyst is contained in a liquid (for example, a solution) containing the raw material compound and a lower carboxylic acid so that the heterogeneous catalyst can be brought into contact with the raw material compound. For example, when a heterogeneous catalyst is accommodated in a container (a container for accommodating the above catalyst) and used, at least a part of the heterogeneous catalyst in the container is composed of the raw material compound and the lower carboxylic acid. The heterogeneous catalyst may be contained in the mixed solution by immersing the container in the solution so as to come into contact with the solution containing the heterogeneous catalyst so that at least a part of the heterogeneous catalyst is contained in the solution. .

  Further, the mixed solution may be used by adding another solvent to the lower carboxylic acid. Examples of such solvents (other solvents) include aromatic solvents such as benzene, toluene, xylene and chlorobenzene; ether solvents such as ether, THF and dioxane; ester solvents such as ethyl acetate; hexane and cyclohexane , Hydrocarbon solvents such as heptane and pentane; nitrile solvents such as acetonitrile and benzonitrile; halogen solvents such as methylene chloride and chloroform; ketone solvents such as acetone and MEK; amides such as DMF, NMP, DMI and DMAc And system solvents.

  Further, the mixed solution may contain acetic anhydride together with the lower carboxylic acid. By using acetic anhydride in this way, water generated during the reaction can be reacted with acetic anhydride to form acetic acid, and the water generated during the reaction can be removed more efficiently. It becomes. In addition, when such acetic anhydride is used, the amount of acetic anhydride used is not particularly limited, but is preferably 4 to 100 times mol with respect to the raw material compound represented by the general formula (1). . When the amount of acetic anhydride used is less than the lower limit, the reaction rate tends to decrease, and when it exceeds the upper limit, the yield tends to decrease.

  Further, the mixed solution includes a by-product (for example, an ester compound of lower carboxylic acid and water) generated during the production of the carboxylic acid anhydride from the mixed solution in order to efficiently evaporate and remove the by-product. You may add the compound (azeotropic agent) which produces a boiling phenomenon. The azeotropic agent is not particularly limited as long as it does not react with the raw material compound and the lower carboxylic acid, and a known azeotropic agent can be appropriately used. Examples of such an azeotropic agent include hydrocarbons such as benzene, toluene, pentane, hexane, cyclohexane, heptane, and octane; ethers such as diethyl ether, propyl ether, and tetrahydrofuran; methylene chloride, chloroform, trichloroethane, and the like. Of halogenated hydrocarbons can be preferably used. Moreover, the usage-amount of the said azeotropic agent is not restrict | limited in particular, What is necessary is just to adjust suitably according to the kind of said raw material compound, the said lower carboxylic acid, and the kind of azeotropic agent to be used.

  As mentioned above, although the raw material compound used for the manufacturing method of the carboxylic acid anhydride of this invention, C1-C5 carboxylic acid, and a liquid mixture were demonstrated, each process for manufacturing a carboxylic acid anhydride is demonstrated below. .

(About each process for manufacturing a carboxylic acid anhydride)
The method for producing a carboxylic acid anhydride of the present invention is a method for producing a carboxylic acid anhydride, in which the mixed liquid is heated to remove a distillate component to obtain a carboxylic acid anhydride,
Before removing the distillate component, a step of separating the carboxylic acid having 1 to 5 carbon atoms from the vapor generated from the mixed solution by the heating (a step of separating the lower carboxylic acid);
And a step of supplying a carboxylic acid having 1 to 5 carbon atoms obtained by the separation step to the mixed solution (a step of supplying a lower carboxylic acid after separation).

  In the present invention, as described above, the mixed solution is heated to obtain a carboxylic anhydride (mixed solution heating step). Although it does not restrict | limit especially as temperature conditions (temperature conditions at the time of heating) in the heating process of such a liquid mixture, It is preferable to set it as 30-300 degreeC, It is more preferable to set it as 50-250 degreeC, 80-200 More preferably, it is set to ° C. Moreover, when the heterogeneous catalyst which can be used suitably for this invention is contained in the said liquid mixture, the temperature conditions (temperature conditions at the time of a heating) in the said heating process shall be 80-180 degreeC. Is preferable, and it is more preferable to set it as 100-140 degreeC. If such a temperature condition is less than the lower limit, the reaction does not proceed sufficiently, and the target carboxylic anhydride tends to be unable to be produced sufficiently efficiently. On the other hand, if the upper limit is exceeded, the reaction Corrosion of equipment and the like becomes remarkable, and tends to be industrially disadvantageous.

  Moreover, it does not restrict | limit especially as pressure conditions (pressure conditions at the time of heating) in the heating process of the said liquid mixture, However, It is preferable that it is 0.001-1.0 MPa, and it is 0.05-0.5 MPa. More preferably, it is still more preferably 0.01 to 0.1 MPa. When the pressure condition is less than the lower limit, the distillation rate of the lower carboxylic acid is increased, and the amount of the lower carboxylic acid tends to be increased, which tends to be disadvantageous in cost. When a substance having a boiling point lower than that of the lower carboxylic acid is present as a by-product (such as water), it is difficult to sufficiently improve the distillation rate of the by-product, and the reaction time is necessarily shortened sufficiently. Tend to become impossible. That is, when the heating step is performed within the pressure range, the by-product generated in the mixed solution can be more efficiently removed, and the reaction time tends to be sufficiently shortened.

  In addition, the heating time in the heating step of the mixed solution is not particularly limited, but is preferably 0.5 to 100 hours, and more preferably 1 to 50 hours. If the heating time is less than the lower limit, the reaction does not proceed sufficiently, and a sufficient amount of carboxylic anhydride tends to be unable to be produced. On the other hand, if the upper limit is exceeded, the reaction proceeds further. However, there is a tendency that the production efficiency is lowered and the economy is lowered. The atmosphere gas in the heating step of the mixed solution is not particularly limited, and may be air or an inert gas (nitrogen, argon, etc.), for example.

  In addition, in the heating step of the mixed solution, the reaction may be performed by heating the mixed solution while stirring from the viewpoint of allowing the reaction to proceed uniformly. In the case where the heterogeneous catalyst that can be suitably used in the present invention is accommodated in a container for accommodating the heterogeneous catalyst (hereinafter simply referred to as “accommodating container” in some cases), the stirring step is performed. When the container is flowed in the lower carboxylic acid, it contacts (impacts) the walls of the reaction container, stirring blades, etc., and the container is deformed to cause the heterogeneous system. Since the problem that the catalyst comes out of the container may occur, the catalyst is fixed in the reaction container in the stirring process (for example, the container is tied to the stirring blade itself so as not to collide with the wall or the stirring blade. Are preferably fixed to the wall of the reaction vessel.

In the heating step of the mixed solution, at least from the group represented by the formula: —COOR ² and —COOR ³ in the raw material compound (when X and Y are groups represented by —COOR ⁴ and —COOR ⁵⁾ In some cases, also from those groups), the following general formula (3):
^{* 5} -CO-O-OC- ^{* 6} (3)
[In the formula (3), * 5 and * 6 are groups represented by the formula: —COOR ² and —COOR ³ in the raw material compound (in the case where X and Y are groups represented by —COOR ⁴ and —COOR ⁵⁾ , respectively. Represents a bond bonded to a carbon atom to which a group represented by —COOR ² and —COOR ³ and a group represented by —COOR ⁴ and —COOR ⁵ , respectively, was bonded. ]
To form a carboxylic acid anhydride. The reaction in which such a carboxylic acid anhydride is generated will be briefly described by taking the case of using the spiro compound represented by the general formula (2) as an example. The reaction is represented by the following reaction formula (I):

[In Reaction Formula (I), R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , n are R ² , R ³ , R ⁴ , R described in General Formula (2) above] ⁵ , R ⁶ , R ⁷ , R ⁸ , and n are the same (preferred examples are also the same). ]
The reaction is represented by Thus, when a spiro compound represented by the above general formula (2) is used as the raw material compound, a tetracarboxylic acid anhydride represented by the above general formula (4) is obtained. In addition, since the carboxylic acid anhydride obtained as a final product by such a heating step has extremely low solubility in the lower carboxylic acid, it can be obtained as a precipitate in the lower carboxylic acid. Is possible.

In addition, although the reaction that occurs in the heating step of such a mixed solution is not necessarily clear, X in the general formula (1) as the raw material compound is a group represented by the formula: —COOR ⁴ , and Y is the formula: A group represented by —COOR ⁵ , wherein X and Y are each connected to adjacent carbon atoms in the compound, and R ² , R ³ , R ⁴ and R ⁵ are all groups other than hydrogen atoms; The case of using a compound and further using acetic acid as the lower carboxylic acid (preferred embodiment) will be described as an example. The following reaction formulas (II) and (III):

[In the reaction formula (II), R ¹ has the same meaning as R ¹ in the general formula (1), and R ² , R ³ , R ⁴ , and R ⁵ are the same as those in the general formula except that they are other than hydrogen atoms. It is the same as R ² , R ³ , R ⁴ and R ⁵ described in (1), and R is any group of R ² , R ³ , R ⁴ and R ^{5 in} the raw material compound. It shows that. ]

[In Reaction formula (III), ^{R 1} is the same as the ^{R 1} described in the above general formula (1). ]
It is inferred that the reaction will be expressed as In addition, such reaction formula (II) shows the reaction which decomposes | disassembles the ester group in a raw material compound, and reaction formula (III) shows the subsequent acid-anhydride reaction. It is presumed that the reaction for decomposing the ester group represented by the reaction formula (II) with carboxylic acid and the subsequent acid anhydride reaction represented by the reaction formula (III) occur continuously. Further, when R ² , R ³ , R ⁴ , and R ⁵ in the raw material compound are all hydrogen atoms, the reaction represented by the above reaction formula (III) proceeds as it is by the heating step of the mixed solution. It will be. That is, in the present invention, when the raw material compound is an ester compound (for example, a raw material compound in which at least R ² and / or R ^{3 in the} general formula (1) is other than a hydrogen atom), the mixture By heating the liquid, it becomes possible to efficiently convert the ester group in the ester compound to a carboxylic acid group (—COOH) as in the reactions represented by the above reaction formulas (II) and (III). By continuing to heat the carboxylic acid compound thus obtained as it is, dehydration condensation can be performed efficiently, and a carboxylic acid anhydride group can be formed by a series of steps even if a raw material compound containing an ester group is used.

The reactions for producing carboxylic acid anhydrides exemplified in the above reaction formulas (II) and (III) are both equilibrium reactions. Therefore, the reaction represented by the reaction formula (II) and the reaction represented by the reaction formula (III) are represented by an ester of acetic acid (formula: CH ₃ COOR) by-produced in each reaction. The more acetate and water remain in the reaction system, the slower the reaction proceeds. Therefore, from the viewpoint of efficiently producing the target carboxylic acid anhydride, the raw material compound is an ester compound (for example, at least R ² and / or R ^{3 in the} general formula (1) is other than a hydrogen atom). In the case of a raw material compound or the like, an ester of a lower carboxylic acid by-produced in a reaction (for example, a reaction represented by the above reaction formula (II)) that decomposes an ester group in the raw material compound with a carboxylic acid ( In the reaction represented by the above reaction formula (II), it is necessary to remove at least a part of the formula: acetate represented by CH ₃ COOR) from the reaction system, and the acid anhydride reaction ( For example, in the reaction represented by the reaction formula (III), it is necessary to remove at least a part of water by-produced during the reaction out of the reaction system. Here, the carboxylic acid anhydride has a very low solubility in the lower carboxylic acid, and tends to easily precipitate as a precipitate during the reaction. Therefore, the above equilibrium reaction is basically a reaction advantageous for the production of an acid anhydride. Moreover, when a by-product (water or the like) is distilled off in such an equilibrium reaction, the reaction becomes a reaction more advantageous for the production of an acid anhydride. Therefore, in the production of carboxylic acid anhydrides, the by-product is distilled off and the distillate component is removed, thereby allowing the carboxylic acid anhydride production reaction to proceed more efficiently.

  From such a point of view, in the method for producing a carboxylic acid anhydride of the present invention, in order to efficiently obtain the carboxylic acid anhydride, the mixed solution is heated, and from the vapor generated from the mixed solution by the heating. After separating the carboxylic acid having 1 to 5 carbon atoms, the distillate component is removed. Thus, after separating the carboxylic acid having 1 to 5 carbon atoms from the vapor generated from the mixed solution by the heating, by performing a step of removing the distillate component (distillation component removal step), Carboxylic anhydride can be efficiently produced while removing by-products from the reaction system.

  In addition, the said liquid mixture is heated, The vapor | steam which arises by the heating contains C1-C5 carboxylic acid, water, ester of a lower carboxylic acid (when a raw material compound is an ester compound), other solvent (said said In the case where the mixed solution uses another solvent). Therefore, as in the conventional case, when the mixture is heated and the vapor generated by the heating is removed (distilled) as it is to remove the distillate component, Since the carboxylic acid is also included, the amount of the lower carboxylic acid in the reaction system decreases, and the carboxylic acid anhydride formation reaction cannot proceed sufficiently efficiently. Therefore, conventionally, the lower carboxylic acid reduced by evaporation as a vapor and the lower carboxylic acid consumed by the reaction (lower carboxylic acid removed as an ester of the lower carboxylic acid) are continuously added. In other words, a method of heating by supplying to the reaction system has been adopted. However, when new lower carboxylic acid is continuously supplied while simply removing the distillate component in this way, the amount of the lower carboxylic acid used increases and the cost increases. Therefore, in the present invention, in order to sufficiently reduce the amount of lower carboxylic acid used, the steam generated from the mixed solution by the heating before the distillate component is removed by the distillate component removal step. The carboxylic acid having 1 to 5 carbon atoms is separated from the inside. And the C1-C5 carboxylic acid obtained by such a separation process is supplied to the said liquid mixture. That is, when the raw material compound and the lower carboxylic acid are heated to obtain a carboxylic acid anhydride, when the distillate component is removed as it is (for example, when the vapor is distilled off from the reaction system as it is), The distillate component contains a lower carboxylic acid ester compound (by-product) and water (by-product), and also contains a large amount of lower carboxylic acid that evaporates by heating. Prior to removing the components, the lower carboxylic acid is separated from the vapor generated from the mixed solution by the heating, and the lower carboxylic acid obtained after the separation is supplied to the mixed solution. It is possible to reuse the lower carboxylic acid that has been produced, and to sufficiently reduce the total amount of the lower carboxylic acid used.

  Thus, in the present invention, before removing the distillate component, the carboxylic acid having 1 to 5 carbon atoms is separated from the vapor generated from the mixed solution by the heating (lower carboxylic acid separation step). ). The method for separating the lower carboxylic acid from the vapor before the removal of the distillate component (the step of separating the lower carboxylic acid) is not particularly limited. For example, before removing the distillate component, A known method such as a method of fractionally distilling a lower carboxylic acid using a difference in boiling point of each component contained in the vapor generated from the mixed solution can be appropriately used. Moreover, the separation step of the carboxylic acid having 1 to 5 carbon atoms (separation step of the lower carboxylic acid) is preferably a step of separating the carboxylic acid having 1 to 5 carbon atoms by fractional distillation. From a general viewpoint, it is more preferable to use a rectification column with simpler equipment. Thus, by using a rectification column, it becomes possible to fractionate and distill lower carboxylic acid more efficiently. The step of separating the carboxylic acid having 1 to 5 carbon atoms from the steam is a step of fractionally distilling the lower carboxylic acid directly from the steam (for example, the steam is directly introduced into the rectification column, etc.). Or a step of separating the carboxylic acid having 1 to 5 carbon atoms using the distillate after the vapor is liquefied once to obtain a distillate (vapor). Or a method of separating a carboxylic acid having 1 to 5 carbon atoms).

  The configuration of such a rectifying column is not particularly limited, and may be appropriately designed so that the target lower carboxylic acid can be separated and separated by fractional distillation from the vapor generated from the mixed solution by the heating, A well-known structure can be employed as appropriate, and for example, a packed tower system, a plate tower system, a plate fin system, or the like may be used. Thus, as the rectifying tower, for example, a bubble bell tower, a perforated plate tower, a packed tower (for example, those using Raschig rings, Lessing rings, Dixon packing, etc.) can be used as appropriate. The number of theoretical plates in such a rectifying column is not particularly limited, but is preferably 0.1 to 50, more preferably 1 to 30. The fractional distillation step in the rectifying column is more suitable for the conditions such as distillation temperature and pressure among the known conditions depending on the configuration of the rectifying column and the type of lower carboxylic acid to be separated. What is necessary is just to implement, changing suitably so that it may become. Therefore, you may perform the fractional distillation process in such a rectification column, for example on the conditions of the distillation temperature of 30-300 degreeC by the pressure of 0.001-1.0 MPa. In addition, the separation process of the lower carboxylic acid using the rectifying column in this way is a process capable of efficiently separating the lower carboxylic acid while being a very simple method.

  Further, in the step of separating the lower carboxylic acid from the vapor generated from the mixed solution by heating before the removal of the distillate component, the amount of the lower carboxylic acid separated is contained in the vapor. It is preferably 5 to 98% by mass, more preferably 10 to 95% by mass, based on the total amount when all of the lower carboxylic acid is distilled. If the amount (ratio) of the lower carboxylic acid separated from the vapor generated from the mixed solution by the heating is less than the lower limit, it is sufficient to reduce the amount of the lower carboxylic acid used in consideration of the cost of introducing equipment that contributes to the separation. On the other hand, in order to exceed the upper limit, complicated equipment tends to be required. The amount of the lower carboxylic acid that can be separated can be easily within the above range (mass%) by, for example, a method using a rectifying column as described above.

  Thus, in the present invention, before removing the distillate component, a step of separating the carboxylic acid having 1 to 5 carbon atoms from the vapor generated from the mixed solution by the heating is performed. Therefore, in the step of removing the distillate component, the remaining component after separating the carboxylic acid having 1 to 5 carbon atoms from the vapor is removed from the distillate component (after separating the carboxylic acid having 1 to 5 carbon atoms). The resulting component is sometimes removed as “second distillate”). Thus, in the present invention, the distillate component to be removed is obtained after separating the carboxylic acid having 1 to 5 carbon atoms from the vapor generated from the mixed solution by the heating (after the separation step of the lower carboxylic acid). Component (distilled component: second distillate). Thus, the method for removing the distillate component (second distillate) obtained after the separation step of the lower carboxylic acid is not particularly limited, and a known method can be used as appropriate, for example, a Liebig condenser. Is used to remove the distillate component (second distillate) after separating the carboxylic acid having 1 to 5 carbon atoms by distilling off the vapor after separating the carboxylic acid having 1 to 5 carbon atoms. The method of performing etc. may be employ | adopted suitably. Thus, by removing the components after separating the carboxylic acid having 1 to 5 carbon atoms from the steam, water produced as a by-product is distilled components (components obtained by distilling off the steam) ) Can be easily removed, and the carboxylic acid anhydride can be produced more efficiently. That is, according to such a method, a C1-C5 carboxylic acid required for the reaction system is efficiently removed while removing distillate components including by-products such as an ester compound of lower carboxylic acid and water. It is possible to sufficiently suppress the removal of the acid out of the system. In the step of removing the distillate component (second distillate), from the viewpoint of more efficiently removing by-products (for example, lower carboxylic acid esters and water), by-products are formed in the mixture. You may add the compound (azeotropic agent) which produces an azeotropic phenomenon with a thing. The lower carboxylic acid separation step and the distillate component (second distillate) removal step include, for example, introducing steam generated from the mixed solution by the heating into a rectification column, It may be carried out continuously, for example, by distilling off the steam after passing through the distillation column.

  Moreover, in this invention, the C1-C5 carboxylic acid obtained by the said isolation | separation process is supplied to the said liquid mixture (supply process of the lower carboxylic acid after isolation | separation). Thus, after separating the carboxylic acid having 1 to 5 carbon atoms from the vapor generated from the mixed solution by the heating step, the carboxylic acid having 1 to 5 carbon atoms (carbon after separation) obtained by the separation step. The method for supplying the carboxylic acid having a number of 1 to 5 to the mixed solution is not particularly limited, and the carboxylic acid having 1 to 5 carbon atoms obtained by the separation step can be supplied to the mixed solution. Such known methods can be adopted as appropriate. As a method of supplying such a mixed solution, for example, a method of supplying the separated carboxylic acid having 1 to 5 carbon atoms by dropping it into the mixed solution using a dropping funnel, or using a rectifying column When the carboxylic acid having 1 to 5 carbon atoms is separated and the rectifying column is connected to the reaction vessel, the carboxylic acid having 1 to 5 carbon atoms after the separation is purified with respect to the mixture being heated. The reaction vessel and the rectifying column are designed so that they are supplied from the distillation column (for example, added by dropping or the like), and the carboxylic acid having 1 to 5 carbon atoms after separation is supplied from the rectifying column to the mixed solution. By supplying, a method of supplying the carboxylic acid having 1 to 5 carbon atoms after the separation to the mixed solution may be appropriately employed. In addition, as such a reaction container, the well-known reaction container which can be utilized for the manufacturing method of carboxylic anhydride can be utilized suitably. The conditions such as the supply rate when supplying the lower carboxylic acid after separation are not particularly limited, and the reaction proceeds efficiently according to the type of lower carboxylic acid used, the size of the reaction vessel, and the like. What is necessary is just to set suitably.

  Even when the lower carboxylic acid obtained in this manner is separated and the lower carboxylic acid obtained after the separation is supplied to the mixed solution and the lower carboxylic acid obtained by the separation is reused, the accuracy of distillation is reduced. In some cases, a part of the lower carboxylic acid can be removed as a distillate component together with the by-product, and when the raw material compound is an ester compound, at least a part of the lower carboxylic acid is used in the reaction, From the viewpoint of allowing the reaction to proceed more efficiently from the fact that it becomes a byproduct (an ester compound of a lower carboxylic acid) and is removed from the reaction system, the lower carboxylic acid supply step after the separation as described above is performed. In addition, it is preferable to separately provide a step of supplying a new lower carboxylic acid to the mixed solution. Thus, also in the present invention, it is preferable that the lower carboxylic acid reduced in the heating step of the mixed solution and the distilling component removing step is newly supplied to the mixed solution from the outside. Even when the reduced amount of the lower carboxylic acid is newly supplied from the outside, in the present invention, the heating (the mixing) is performed before the distillate component is removed in the distillate component removal step. Since the lower carboxylic acid is separated from the vapor generated from the mixed solution by the liquid heating step), the amount of decrease in the lower carboxylic acid is small in the first place, compared with the conventional method for producing a carboxylic acid anhydride. The supply amount can be suppressed to a sufficiently small amount. Therefore, in the present invention, the amount (total amount) of the carboxylic acid having 1 to 5 carbon atoms used throughout the carboxylic acid anhydride production process is sufficiently suppressed as compared with the conventional method for producing carboxylic acid anhydride. Can do.

  In addition, the heating step of the mixed solution may include a step of heating and refluxing the mixed solution from the viewpoint of more efficiently generating a carboxylic acid anhydride. Thus, it becomes possible to manufacture a carboxylic anhydride more efficiently by including a refluxing step in the heating step of the mixed solution. That is, in the heating process of the mixed solution, since the reaction does not sufficiently proceed in the initial stage of heating, almost no by-products such as water are generated. Therefore, the by-product is hardly contained in the steam at the initial stage of heating. Therefore, until the reaction proceeds to some extent (the initial stage of heating), the carboxylic acid anhydride can be produced without much influence of by-products (such as water) without removing the distillate component. And by refluxing in such a stage, it becomes possible to advance a reaction efficiently using lower carboxylic acid, and, thereby, it becomes possible to produce | generate a carboxylic acid anhydride more efficiently. The degree of progress of the reaction can be determined by confirming the amount of the ester compound of the lower carboxylic acid contained in the steam. Therefore, when the reflux step is performed, the reflux time is appropriately set so that the reaction proceeds efficiently while confirming the amount of the ester compound of the lower carboxylic acid in the steam, and then the distillate component is heated while heating. You may perform the removal process. Further, such reflux conditions are not particularly limited, and known conditions can be appropriately employed, and can be appropriately changed to suitable conditions according to the type of the raw material compound used.

  In the present invention, from the viewpoint of efficiently carrying out the carboxylic acid decomposition reaction of the ester group in the raw material compound and the subsequent anhydride reaction, for example, the step (A) of heating and refluxing the mixed solution and the mixing A portion of the liquid in the liquid was distilled off under reduced pressure to remove the distillate component, and the mixture was concentrated, and the resulting concentrated liquid was again supplied with the lower carboxylic acid and heated to reflux. A part of the liquid in the obtained mixed liquid is again distilled off under reduced pressure, thereby removing again the distillate component and concentrating to obtain a concentrated liquid; and the lower carboxylic acid is added to the concentrated liquid And a step (C) of obtaining a carboxylic acid anhydride by heating the obtained mixed solution may be used. In such steps (A) to (C), when the distillate component is removed by distillation under reduced pressure, a separation step of the lower carboxylic acid is applied, and the concentrated liquid of the mixed solution is subjected to lower carboxylic acid. In the heating step of the step (C), when the vapor is distilled off, the lower carboxylic acid separation step and the post-separation step may be performed. The lower carboxylic acid supply step may be performed. In step (C), acetic anhydride may be supplied together with the lower carboxylic acid. In these steps (A) and (B), the carboxylic acid decomposition reaction of the ester group in the raw material compound proceeds mainly, and in the step (C), the anhydride reaction proceeds mainly. .

  Moreover, in the manufacturing method of the carboxylic acid anhydride of this invention, the said liquid mixture is heated as mentioned above, and a carboxylic acid anhydride is obtained. After the carboxylic acid anhydride is thus produced, when a catalyst is used for the production, a separation step between the product and the catalyst may be appropriately performed. In addition, after heating the mixed solution as described above to obtain a crude product of carboxylic acid anhydride from the raw material compound represented by the general formula (1), the crude product is reused. Purification steps such as crystallization and sublimation may be appropriately performed. Such a purification step makes it possible to obtain a carboxylic acid anhydride with higher purity. In addition, it does not restrict | limit especially as such a purification method, A well-known method is employable suitably.

  As described above, in the present invention, in the method for producing a carboxylic acid anhydride in which the mixed liquid is heated and the distillate component is removed to obtain the carboxylic acid anhydride, before the distillate component is removed, C1-C5 carboxylic acid is isolate | separated from the vapor | steam produced from the said liquid mixture by heating, and the C1-C5 carboxylic acid after this isolation | separation is supplied to the said liquid mixture. Therefore, in the present invention, it is possible to sufficiently reduce the amount of the carboxylic acid having 1 to 5 carbon atoms that is distilled out of the reaction system through the production process of the carboxylic acid anhydride, and thus the carbon used. It becomes possible to sufficiently reduce the amount (total amount) of the carboxylic acids of several 1-5. As described above, according to the present invention, an increase in the amount of the carboxylic acid having 1 to 5 carbon atoms that hinders the production of an inexpensive product is sufficiently suppressed, and the amount of the carboxylic acid having 1 to 5 carbon atoms to be used ( The total amount) can be sufficiently reduced, and the carboxylic acid anhydride can be produced efficiently. Therefore, the method for producing a carboxylic acid anhydride of the present invention can produce a carboxylic acid anhydride at a lower cost, and is particularly useful as a method for industrially producing a carboxylic acid anhydride.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
First, 5 g of an acid ion exchange resin (trade name “Amberlite 200C” manufactured by Organo Corporation, average particle size: 0.60 to 0.85 mm) was prepared as a catalyst. Next, an envelope-type bag made of polyphenylene sulfide (PPS) mesh cloth (trade name “PPSP60” manufactured by NBC Meshtec Co., Ltd., number of meshes per inch: 60 mesh). : Having a size of 46 mm, no gusset, and an opening on the short side.), 2.5 g of the catalyst is put into the envelope-type bag, and openings at both ends of the bag are formed. By sewing with multifilament yarn made of the same material (PPS) as the mesh cloth, 2.5 g of the catalyst made of ion exchange resin was accommodated in the bag, and two bags were prepared.

  Next, a packed tower type rectification tower having a theoretical plate number of 1.8 (a glass filler manufactured by Asahi Seisakusho Co., Ltd., trade name “multiple turn”) was used to fill a glass tube with an inner diameter of 30 mm to a height of about 100 mm. And a flask having an internal volume of 500 ml connected to a Liebig condenser was prepared as a reaction vessel. The rectifying column and the Liebig condenser are each placed in the flask so that when the liquid is heated in the flask and vapor is generated, the vapor passes through the Liebig condenser after passing through the rectifying column. Connected (installed). That is, a portion (one opening portion of the glass tube having an inner diameter of 30 mm) serving as the vapor inlet of the rectifying column is connected to an opening portion of the flask, and an outlet portion of the vapor from the rectifying column (the inner diameter of 30 mm). A Liebig condenser was connected to the other opening of the glass tube. The rectification column was installed so that the acetic acid fractionally distilled in the rectification column was again introduced into the flask as it was (returned).

  Next, the following general formula (5):

20 g of a raw material compound (norbornane-2-spiro-α-cyclopentanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic acid tetramethyl ester) A solution (mixed solution) dissolved in 330 ml of acetic acid was prepared, and the solution was added to the flask (reaction vessel). The raw material compound was prepared according to the method disclosed in Example 1 described in International Publication 2011/099518.

  Next, the bag (two) containing 2.5 g of the ion exchange resin prepared as described above is completely immersed in the solution (mixed solution) added to the flask. Thus, an ion exchange resin (total amount: 5 g) was added to the solution, and the ion exchange resin was contained in the solution. Each bag was hung with a string so that the catalyst-filled bag was fixed so as not to come into contact with the wall of the flask or the stirring rod when stirring with a magnetic stirrer. Thus, the liquid mixture which contains the said ion exchange resin, the said raw material compound, and the said acetic acid in the flask was obtained. The content ratio of the raw material compound and the heterogeneous catalyst in the mixed solution ([raw material compound (molar amount)]: [catalyst (molar amount in terms of functional group)]) is 1: 0.3 (raw material compound) Of the heterogeneous catalyst with respect to the content (molar amount) of 0.3 mol), the content of the raw material compound in the acetic acid is 5.7% by mass, and the acetic acid The content of was 131 times mol with respect to the molar amount of the raw material compound.

  Next, after reducing the pressure in the flask to 700 mmHg (0.093 MPa), the mixture is heated with a magnetic stirrer so that the temperature in the flask becomes 115 ° C. After 1 hour, maintaining the heating condition at 115 ° C., introducing the steam generated from the mixed solution into the rectification column, and then introducing the steam after passing through the rectification column into the Liebig condenser. The acetic acid is fractionally distilled from the steam generated in the flask, and the steam after the fractional distillation is distilled off (distilled component is removed). At the same time, the amount of the liquid mixture in the flask is reduced. Acetic acid was added into the flask using a dropping funnel so as to be constant (hereinafter, this step is referred to as step (i)). In such step (i), acetic acid was fractionally distilled from the steam before removing the distillate component by the rectification column, and the fractionally distilled acetic acid was returned to the mixed solution. Here, the fractionally distilled acetic acid could be returned from the rectifying column at a rate of about 90 mL / h. Moreover, in the vapor | steam distillation process in such a process (i), the distillation speed | rate of the distillate component obtained after passing the said Liebig condenser was about 10 mL per hour. Further, the distillate component (distillate) distilled off in this way was collected every hour, and the mass of the distillate component was measured and analyzed by gas chromatography. The presence of acetic acid, methyl acetate and water was confirmed in the liquid). Moreover, in the said process (i), the white precipitate began to produce | generate in the said liquid mixture after 8 hours passed since the removal of the distillate component was started. Further, after 10 hours from the start of the removal of the distillate components, the heating was terminated (step (i) was terminated), and the reaction was stopped. Thereafter, all the bags containing the catalyst were taken out from the flask. In addition, when taking out the bag containing the catalyst, the solid content adhered to each bag is separated from the bag by scraping with tweezers or a spoon, and the solid content obtained by such separation is mixed again. Returned to liquid. Subsequently, solid content was taken out from the liquid mixture in a flask by performing filtration under reduced pressure using a filter paper, and white solid was obtained. The obtained white solid was washed with toluene and dried to obtain 11.5 g of white powder.

  A part of the powder thus obtained was collected and subjected to liquid chromatographic analysis. As a result, the obtained white powder gave a single peak (a single product was obtained). I understood. Further, when NMR measurement and LC measurement were performed in order to identify the kind of the powdered compound thus obtained, the obtained compound was represented by the following general formula (6):

It was confirmed that it was the compound represented (carboxylic anhydride). In addition, when the yield with respect to the theoretical amount of the product computed from the preparation amount of the raw material compound used was calculated | required, it was confirmed that a yield is 71%. It was also found that the crystals of the obtained compound showed the original crystal color (white), and the obtained crystals were not colored. The amount of methyl acetate in the total amount of distillate after 10 hours from the start of distillation (total amount of distillate obtained until 10 hours after the start of distillation) was 10.6 g. The amount of water was found to be about 1.2 mL and the amount of acetic acid was about 100 mL. As will be described later, in Comparative Example 1 performed without connecting a rectifying column, the amount of acetic acid distilled out was about 1000 mL. Therefore, in Example 1, the distillation of steam during step (i) was performed. In the last step, it was found that about 90% by mass of acetic acid could be separated and reused by the rectification column with respect to the total amount of acetic acid in the steam before fractional distillation.

(Comparative Example 1)
A flask having an internal volume of 500 ml, to which only a Liebig condenser was connected, without using a rectifying column, was used as a reaction vessel, and in step (i), the pressure was not reduced to 700 mmHg but normal pressure (760 mmHg, 0 Carboxylic anhydride was obtained in the same manner as in Example 1 except that heating was started under the condition of 0.1 MPa). The white powder (carboxylic acid anhydride) thus obtained was 10.2 g. Moreover, when the kind of powder compound was identified like Example 1, it was confirmed that it is a compound (carboxylic anhydride) represented by the said General formula (6). Moreover, when the yield with respect to the theoretical amount of the product computed from the preparation amount of the raw material compound used was calculated | required, it was confirmed that a yield is 63%. Moreover, in the vapor | steam distillation process in process (i), the distilling speed | rate of the distillate component obtained after passing the said Liebig condenser was about 100 mL / h. Furthermore, the amount of methyl acetate in the total amount of distillate after 10 hours from the start of distillation (total amount of distillate obtained until 10 hours after the start of distillation) was 9.4 g. It was found that the amount of water was about 1.1 mL and the amount of acetic acid was about 1000 mL.

  As is clear from the results of Example 1 and Comparative Example 1, when acetic acid was separated by fractional distillation using a rectifying column and the separated acetic acid was added to the mixture again (Example 1). ), While the distillation rate of the distillate component in the distillate removal step in step (i) is about 10 mL / h, the distillate component is simply used without using a rectification column. When removed (Comparative Example 1), the distillation rate of the distillate component was about 100 mL / h. Further, the amount of acetic acid that had to be newly added during the heating of the mixed solution (the amount of acetic acid added from the outside) was about 100 mL in Example 1, whereas in Comparative Example 1, Was about 1000 mL. Further, as described above, the amount of methyl acetate obtained until 10 hours have passed since the start of the removal of the distillate component was 10.6 g in Example 1, whereas it was 9 in Comparative Example 1. .4 g. From these results, in the case of using a flask with a rectifying column (Example 1), the amount of acetic acid distilled out was lower than in the case of using a flask without a rectifying column (Comparative Example 1). It was found that methyl acetate and water can be sufficiently distilled off with a small amount. Further, in Example 1, 11.5 g of carboxylic acid anhydride was obtained, whereas in Comparative Example 1, the amount of carboxylic acid anhydride obtained was 10.2 g. For example, it was found that the carboxylic acid anhydride can be obtained more efficiently under the conditions employed in Example 1. In Example 1, although the pressure was reduced during heating, the inventors speculate that the distillation rate of methyl acetate / water, which is a low-boiling point substance, is higher than that of acetic acid under reduced pressure conditions. In view of this, the present inventors presume that the reaction proceeds efficiently in Example 1. Therefore, the present inventors speculate that in the method for producing a carboxylic acid anhydride of the present invention, when the mixed liquid is heated, the reaction time can be further shortened by heating under a reduced pressure condition. doing.

  As described above, according to the present invention, a method for producing a carboxylic acid anhydride that can efficiently produce a carboxylic acid anhydride by sufficiently reducing the amount of carboxylic acid having 1 to 5 carbon atoms. Can be provided. Such a method for producing a carboxylic acid anhydride of the present invention can sufficiently reduce the amount of carboxylic acid having 1 to 5 carbon atoms, and thus is a method capable of sufficiently reducing the cost. It is particularly useful as a method used when industrially producing carboxylic acid anhydrides.

Claims (6)

The following general formula (1):

[In Formula (1), R ¹ is a tetravalent organic group having at least two adjacent carbon atoms, and the groups represented by the formulas: —COOR ² and —COOR ³ are present on the two adjacent carbon atoms. Each is connected,
R ² and R ³ may be the same or different and are each a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or carbon. 1 type selected from the group consisting of an aryl group having 6 to 20 carbon atoms and an aralkyl group having 7 to 20 carbon atoms,
X is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and the formula: -COOR ^{4 (R 4} has the same meaning as the ^{R 2,} be the same or different and ^{R 2} 1 type selected from the group consisting of groups represented by:
Y represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and the formula: -COOR ^{5 (R 5} has the same meaning as the ^{R 2,} be the same or different and ^{R 2} 1 type selected from the group consisting of groups represented by: ]
A method for producing a carboxylic acid anhydride by heating a mixed solution containing a raw material compound represented by the formula (1) and a carboxylic acid having 1 to 5 carbon atoms and removing a distillate component,
Separating the carboxylic acid having 1 to 5 carbon atoms from the vapor generated from the mixed solution by the heating before removing the distillate component;
And a step of supplying a carboxylic acid having 1 to 5 carbon atoms obtained by the separation step to the mixed solution.   2. The carboxylic acid anhydride according to claim 1, wherein the step of separating the carboxylic acid having 1 to 5 carbons is a step of separating the carboxylic acid having 1 to 5 carbons by fractional distillation. Production method.   The method for producing a carboxylic acid anhydride according to claim 1 or 2, wherein a rectifying column is used in the step of separating the carboxylic acid having 1 to 5 carbon atoms.   The pressure condition at the time of heating the said liquid mixture is 0.001-1.0 Mpa, The manufacturing method of the carboxylic acid anhydride as described in any one of Claims 1-3 characterized by the above-mentioned.   5. The method for producing a carboxylic acid anhydride according to claim 1, wherein a temperature condition for heating the mixed solution is 30 to 300 ° C. 5. The raw material compound is represented by the following general formula (2):

Wherein ^{(2), R 2, R} 3, R 4, R 5 has the same meaning as ^{R 2, R 3, R 4} , R 5 described in the above general formula ^{(1), R 6, R} 7, R ⁸ may be the same or different and each represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms and a fluorine atom, and n represents an integer of 0 to 12 . ]
The manufacturing method of the carboxylic acid anhydride as described in any one of Claims 1-5 which is a spiro compound represented by these.