JP2003135904A - Method for removing zirconium chelate complex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily and efficiently removing a zirconium complex which remains in a reaction product after a synthetic reaction using the zirconium complex as a catalyst. SOLUTION: In the method for easily and efficiently removing the chelate complex of zirconium which remains in the reaction product, after a compound soluble in a water-insoluble organic solvent is synthesized by the reaction using the chelate complex of zirconium as the catalyst, a solution of the reaction product in the water-insoluble organic solvent is washed with an aqueous solution containing a weak acid salt of an alkali metal.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for efficiently removing a zirconium chelate complex remaining in a reaction product after completion of the reaction in a reaction using a zirconium chelate complex as a catalyst.

[0002]

2. Description of the Related Art Zirconium chelate complex (hereinafter, simply referred to as "zirconium complex" unless otherwise specified)
Is a catalyst showing extremely high activity for transesterification reaction and urethanization reaction. However, if this catalyst remains in the reaction product, it may cause deterioration of the reaction product, When the reaction product is used as a raw material for the next step, it may cause an unexpected side reaction. Therefore, it is necessary to remove the zirconium complex from the reaction product as much as possible.

In the reaction using a zirconium complex as a catalyst, the method for removing the zirconium complex remaining in the reaction product includes (1) a method of separating the desired reaction product by distillation, and (2) a reaction product. After dissolving the substance in a water-insoluble organic solvent, washing with acidic water,
(3) A method of reacting the zirconium complex with phosphoric acid to form a precipitate, and separating the precipitate by filtration or centrifugation, and the like.

The method (1) is described in JP-A-53-1.
No. 05418 discloses monovalent higher alcohols and (meth)
A method is disclosed in which the target reaction product is separated by distillation after the completion of the transesterification reaction of acrylic acid with a lower alkyl ester. However, the reaction product is (meta)
In the case of a compound that is unstable to heat, such as a polymerizable compound that easily undergoes polymerization, such as an acrylic ester, it is not preferable to separate it by distillation, and further, the reaction product may be a solid, It is virtually impossible to apply this method to the separation of compounds having a very high boiling point and difficult to separate by distillation.

Regarding the method (2), Japanese Patent Laid-Open No. 2000-
Japanese Patent No. 191589 describes that the zirconium complex can be removed by washing the transesterification reaction product with water or acidic water, but does not disclose any specific method. This method is difficult to apply when the reaction product is a compound that is unstable to acidic water, such as a basic compound.

Regarding the method (3), Japanese Patent Laid-Open No. 2001-2001
Japanese Patent No. 89415 discloses a method in which phosphoric acid is added to a reaction mixture to precipitate a zirconium complex after completion of transesterification reaction between a diol and a (meth) acrylic acid ester, and the zirconium complex is separated by filtration. However, since the particle size of the precipitate deposited by such an operation is very small, it is often necessary to use a special filtration device such as pressure filtration or centrifugal filtration in order to efficiently filter the precipitate. Further, when the reaction product is a basic compound, it forms a salt with phosphoric acid, which is not suitable as a method for removing the zirconium complex.

[0007]

The problem to be solved by the present invention is, in a synthetic reaction using a zirconium complex as a catalyst, to remove the zirconium complex remaining in the reaction product after completion of the reaction by a simple method and efficiently. The purpose of this is to provide a method of removing it selectively.

[0008]

The present inventors have synthesized a compound soluble in a water-insoluble organic solvent by a reaction using a zirconium complex as a catalyst, and then used a solution of the reaction product in a water-insoluble organic solvent as an alkali. The above problem was solved by providing a method for efficiently removing a zirconium complex remaining in a reaction product by a simple method of washing with an aqueous solution containing a weak acid salt of a metal.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method for removing a zirconium complex according to the present invention comprises washing a non-water-soluble organic solvent solution of a reaction product obtained by a synthetic reaction using a zirconium complex as a catalyst with an aqueous solution containing a weak acid salt of an alkali metal. Then, the zirconium complex remaining in the reaction product is transferred to the aqueous layer. Therefore, the reaction product must be soluble in a water-insoluble organic solvent. Since the non-water-soluble organic solvent layer and the water layer do not contain a precipitate and each layer can be carried out in a uniform state, the washing step can be performed by simply separating the non-water-soluble organic solvent layer and the water layer. Is a very simple method that can remove

As the zirconium complex which can be removed by the removing method of the present invention, a chelate complex of zirconium with a 1,3-dicarbonyl compound, a polyamino compound, a polyaminocarboxylic acid compound, a dicarboxylic acid compound or the like can be mentioned. Among these, examples of zirconium chelate complexes of 1,3-dicarbonyl compounds that are industrially readily available and chemically stable include zirconium acetylacetonate, zirconium trifluoroacetylacetonate, zirconium hexafluoroacetylacetonate, Zirconium-2,4-hexadionate, zirconium-3-phenylacetylacetonate, zirconium-3,5-heptanedionate, zirconium-2,2,6,6-tetramethylheptanedionate, zirconium-1,3. -Diphenylacetonate and the like.

The reaction solvent used in the present invention is not particularly limited as long as it dissolves the reaction product, the zirconium complex and the reaction product, but it is not a water-soluble organic solvent such as n-pentane or n-hexane. , N-heptane, n
-Octane, cyclohexane, benzene, toluene, o
If -xylene, m-xylene, p-xylene, mesitylene, ethylbenzene, cumene, etc. are used, after the reaction is completed, the zirconium complex removing step which is the next step can be directly performed without replacing the solvent. When a water-soluble organic solvent is used as the reaction solvent, it is necessary to replace the water-soluble organic solvent with a non-water-soluble organic solvent after the reaction and prior to the next step.

The method for removing a zirconium chelate complex of the present invention can be applied to any reaction as long as the above zirconium complex exhibits catalytic activity and is not particularly limited. Transesterification reaction and urethanization reaction are known as the reaction in which the zirconium complex exhibits catalytic activity, and particularly, the catalytic activity in the transesterification reaction between alcohol and carboxylic acid ester is high.

When the present invention is applied to the above-mentioned transesterification reaction, the alcohol is not particularly limited as long as it has a hydroxyl group in the molecule, and it is not limited to an aliphatic alcohol, an alicyclic alcohol, an aromatic alcohol or a polyol. Is used. These alcohols include alkyl groups, alkylene groups, alkenyl groups, cycloaliphatic groups, phenyl groups, heterocyclic groups, carbonyl groups, alkoxy groups, cyano groups, amino groups, amide groups, nitro groups, halogens, phosphorus-containing groups. It may be substituted with one or more functional groups selected from the substituents.

As the monohydric alcohol, for example, the following structural formula

HO- (R ₁ O) _n -R ₂ (In the formula, R ₁ is a linear or branched alkylene group having 2 to 8 carbon atoms, R ₂ is an alkyl group having 1 to 18 carbon atoms, (A cycloalkyl group, an aralkyl group or an aryl group, and n is 0 or an integer of 1 or more.)

In addition to alkylene glycol monoethers represented by, furfuryl alcohol, tetrahydrofuryl alcohol, benzyl alcohol, 2-phenoxyethanol, cyclohexanol, allyl alcohol, xylose and the like can be mentioned. Examples of monohydric nitrogen-containing alcohols include the structural formulas shown below.

[0016]

Embedded image HO- (R_ThreeO)_n-R_Four-NR₅R₆ (In the formula, R_ThreeHas a straight or branched chain having 2 to 8 carbon atoms
Alkylene group, R_FourIs a straight chain having 2 to 8 carbon atoms or
A branched alkylene group or an arylene group, n is
It is an integer of 0 or 1 or more. R₅And R₆Is the same species
Or different linear or branched alkyl group having 1 to 8 carbon atoms
Group, aralkyl group, R₅, R ₆Tied to each other
Or through a heteroatom to form a ring
You may stay. )

Alkyleneoxyalkylaminoalkanols represented by the formula (1) and hydroxyalkylpyridines are listed as other alcohols.

Examples of the dihydric alcohol include ethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, butanediol, pentanediol, hexanediol, octanediol, decanediol, dodecanediol, tetradecanediol, hexadecanediol, octadecanediol. , Cyclohexanediol, cyclodecanediol, tricyclodecanediol, butynediol, butenediol, hexenediol, octenediol, decenediol, bis (2-hydroxyethyl) -N-methylamine, N, N'-bis (2- Hydroxyethyl) piperazine, and the like.

The carboxylic acid ester to be reacted with the alcohol in the transesterification reaction may be any one of an aromatic carboxylic acid ester, an aliphatic carboxylic acid ester and an alicyclic carboxylic acid ester. It may be monocyclic, polycyclic or condensed polycyclic.

A solvent may or may not be used in the transesterification reaction, but it is desirable to remove the alcohol produced by the transesterification reaction out of the system. It is preferable to use an azeotropic organic solvent. Further, if a water-insoluble organic solvent is used, it is possible to proceed directly to the next step of removing the zirconium complex without replacing the solvent.

Such an organic solvent has 5 to 5 carbon atoms.
10 aliphatic, aromatic, or alicyclic hydrocarbons, or mixtures thereof, such as n-pentane,
Examples thereof include n-hexane, n-heptane, n-octane, cyclohexane, benzene, toluene, o-xylene, m-xylene, p-xylene, mesitylene, ethylbenzene and cumene. Among these hydrocarbon solvents, n-hexane, n-heptane, cyclohexane, benzene, toluene and the like are preferable. After the completion of the reaction, these hydrocarbon solvents are recovered as a mixture with an alcohol produced by the transesterification reaction, but can be reused as a reaction solvent by washing with water to remove the alcohol.

The above transesterification reaction is carried out at 20 to 150 ° C.
It is recommended to carry out in the temperature range. As a raw material, when a polymerizable compound such as (meth) acrylic acid ester is used, it is preferable to react at a temperature as low as possible within the above temperature range, and a known conventional polymerization inhibitor may be added if necessary,
The reaction may be performed in an oxygen-containing atmosphere.

The ratio of the alcohol to the carboxylic acid ester used in the transesterification reaction is not particularly limited, but the molar ratio of the alcohol to the carboxylic acid ester is preferably in the range of 1: 1 to 1:10. .

In the present invention, the weak acid salt of an alkali metal used for removing the zirconium complex includes lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate,
Cesium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, rubidium hydrogen carbonate, cesium hydrogen carbonate, trilithium phosphate, trisodium phosphate, tripotassium phosphate, trirubidium phosphate, tricesium phosphate. . Among these, lithium carbonate, sodium carbonate, potassium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, trilithium phosphate,
Trisodium phosphate, tripotassium phosphate, and the like are industrially widely used, and are preferable from the viewpoint of easy availability, and more preferable are potassium carbonate, potassium hydrogen carbonate, and tripotassium phosphate.

The concentration of the aqueous solution containing the weak acid salt of the alkali metal may be any concentration, but when it is 5 to 50% by mass, the removal operation of the zirconium complex becomes easy. In the step of removing the zirconium complex, the amount of the aqueous solution containing the weak acid salt of the alkali metal is not particularly limited, but the amount of the weak acid salt of the alkali metal contained in the aqueous solution used for the first washing. When the amount is 5 to 20 times on the mass basis with respect to the amount of the zirconium chelate complex to be removed, good removal efficiency can be obtained. Further, the removal rate of the zirconium-containing catalyst increases as the number of washings increases, but the removal method of the present invention enables the zirconium complex to be removed extremely efficiently from the reaction product, and 99% or more after 1 to 3 washings. The removal rate of is obtained.

The zirconium complex that has migrated into the aqueous layer is added with an aqueous solution containing a strong base such as sodium hydroxide to adjust the pH.
When it is 14 or more, a precipitate can be formed and recovered. The zirconium-containing precipitate can be reused as a raw material for the zirconium complex.

The zirconium complex remaining in the reaction product is removed by adding an aqueous solution of a weak acid salt of an alkali metal to a solution of the reaction product in a non-water-soluble organic solvent and stirring vigorously. After stirring for 5 to 30 minutes, the mixture is left to stand to completely separate the organic solvent layer and the aqueous layer, and the aqueous layer to which the zirconium complex is transferred is removed. Repeat this operation multiple times if necessary. Heating the system temperature to 30 to 80 ° C. during this step increases the removal efficiency of the zirconium complex. Then
By distilling off the water-insoluble organic solvent of the obtained organic solvent layer, a reaction product having a very low zirconium complex content can be obtained.

A specific method of applying the present invention to the transesterification reaction will be described below by taking the transesterification reaction as an example. thermometer,
A reaction vessel equipped with a stirrer, a dropping funnel, a fractionating tube, and, if necessary, an air introducing tube, alcohol, a carboxylic acid ester, a zirconium complex, and if necessary, a solvent, a polymerization inhibitor, or a coloring inhibitor, etc. Add the additives and stir while heating in the appropriate temperature range described above. When an organic solvent having a boiling point within the temperature range is used, it is refluxed to remove the produced alcohol by azeotropic distillation with the organic solvent. It is also possible to blow dry air from the air introduction pipe to remove the produced alcohol outside the system. When the produced alcohol is removed by azeotropic distillation with the carboxylic acid ester as a raw material without using an organic solvent, the carboxylic acid ester corresponding to the amount distilled out of the system is supplied from a dropping funnel. In this case, the amount of the carboxylic acid ester distilled out can be reduced by using the fractionating pipe.

During the transesterification reaction, the amount of the desired product in the reaction mixture is monitored by gas chromatography analysis or the like, and the reaction is preferably continued until the reaction rate becomes 90% or more. The required reaction time is usually 2 to 12 hours.
After completion of the reaction, the unreacted starting carboxylic acid ester and the reaction solvent are distilled off from the reaction vessel, and the reaction product in the reaction vessel is dissolved in an inert non-water-soluble organic solvent and taken out. When the reaction product is stable to heat and has an appropriate boiling point, it may be taken out from the reaction vessel by distillation and then mixed with a water-insoluble organic solvent.

The zirconium complex remaining in the reaction product thus taken out is removed by the above-mentioned washing operation, and the organic solvent is distilled off, whereby the desired carboxylic acid having a very low zirconium complex content is obtained. An ester compound can be obtained. According to the method for removing a zirconium chelate complex of the present invention, the content of the zirconium chelate complex remaining in the reaction product can be set to 20 ppm or less, although the method is extremely simple as described above.

[0031]

EXAMPLES The present invention will be described more specifically below with reference to Examples and Comparative Examples. Below, unless otherwise specified
Both "%" and "ppm" are based on mass.

<Gas Chromatographic Analysis Conditions> Gas chromatographic analysis in each of the following Examples and Comparative Examples was carried out under the following conditions. Gas chromatography device: "GC-14A type gas chromatography device" manufactured by Shimadzu Column: 60 mDB-1 (methyl silicon capillary column) Injection part temperature: 300 ° C Column temperature: 80 to 300 ° C (heating rate: 10 ° C / min) ) Detector: Hydrogen flame ionization detector Detection temperature: 300 ° C Carrier gas: He gas

<Measurement of Zirconium Content> The zirconium content of the reaction products obtained in each of the following Examples and Comparative Examples is as follows: Perkin Elmer Inductively Coupled Plasma Atomic Emission Spectrometer (ICP) “Optima 3300 DV”
Was measured using.

(Example 1) Stirrer, dropping funnel, thermometer,
A reaction vessel equipped with a fractionating tube and an air introducing tube was charged with 104 g (1 mol) of neopentyl glycol, 300 g (3 mol) of ethyl acrylate, and 0.2 g of p-methoxyphenol as a polymerization inhibitor. Then, with stirring, 9.75 g of zirconium acetylacetonate
(0.02 mol) was added into the above mixture.

The above mixture was refluxed with stirring, and an azeotropic mixture of ethanol and ethyl acrylate produced by the reaction was distilled through a fractionating tube. At the same time, the same amount of ethyl acrylate as the distillate was added through the dropping funnel. The reaction was continued until the content of neopentyl glycol diacrylate (hereinafter abbreviated as NPGDA) in the reaction mixture exceeded 90%.

After completion of the reaction, unreacted ethyl acrylate was removed by distillation under reduced pressure, 140 g of toluene and 60 g of heptane were added to the residue, and then 60 g of 20% potassium carbonate aqueous solution was added, followed by stirring at 50 ° C. for 30 minutes. Fifty
After standing still at 10 ° C. for 10 minutes, the mixed solution in the reaction vessel was transferred to a separating funnel, the organic solvent layer and the aqueous layer were separated, and the aqueous layer was removed. This washing operation was performed twice in total, and the organic solvent was distilled off from the organic solvent layer under reduced pressure to obtain 194 g of a reaction product.
As a result of gas chromatography analysis of the reaction product,
NPGDA was 98.5% and neopentyl glycol monoacrylate was 1.5%. The zirconium content of the resulting reaction product was less than 1 ppm.

(Example 2) Stirrer, dropping funnel, thermometer,
In a reaction vessel equipped with an air introduction tube and a decanter,
175.8 g of N, N-diethylaminoethanol (1.
5 mol), 516 g (6 mol) of methyl acrylate, and p-methoxyphenol 0.25 as a polymerization inhibitor.
and g. Then, with stirring, 7.31 g (0.015 mol) of zirconium acetylacetonate was added to the above mixture.

The mixture was refluxed with stirring, and an azeotropic mixture of methanol and methyl acrylate produced by the reaction was distilled through a fractionating tube. At the same time, the same amount of methyl acrylate as the distillate was added through the dropping funnel. The reaction was continued until the N, N-diethylaminoethyl acrylate content in the reaction mixture exceeded 90%.

After the reaction was completed, unreacted methyl acrylate was removed by distillation under reduced pressure, 180 g of toluene and 77 g of heptane were added to the residue, 77 g of 20% aqueous potassium carbonate solution was added, and the mixture was stirred at 50 ° C. for 30 minutes. Fifty
After standing still at 10 ° C. for 10 minutes, the mixed solution in the reaction vessel was transferred to a separating funnel, the organic solvent layer and the aqueous layer were separated, and the aqueous layer was removed. The organic solvent was distilled off under reduced pressure from the organic solvent layer, and 23
2.4 g of reaction product was obtained. As a result of gas chromatography analysis of the reaction product, N, N-diethylaminoethyl acrylate was 100%. The zirconium content of the obtained reaction product was 10 ppm.

Example 3 The same operation as in Example 2 was performed except that the washing with a 20% potassium carbonate aqueous solution was performed twice in total. The zirconium content in the obtained reaction product was less than 1 ppm.

Example 4 The same operation as in Example 2 was carried out except that the washing with a 20% tripotassium phosphate aqueous solution was carried out twice in total. The zirconium content of the obtained reaction product was 2 ppm.

Comparative Example 1 After reacting under the same conditions as in Example 1, unreacted ethyl acrylate was removed by distillation under reduced pressure, and 140 g of toluene and 60 g of heptane were added to the residue.
And then 60 g of 10% aqueous sodium hydroxide solution
Was added and stirred at 50 ° C. for 30 minutes. A precipitate was present in the mixture in the reaction vessel, and it took 2 hours or more to separate the precipitate by filtration. After performing the washing operation twice in total, the organic solvent layer and the aqueous layer were separated, and the organic solvent was distilled off from the organic solvent layer under reduced pressure. The zirconium content of the obtained reaction product was 30 ppm.

Comparative Example 2 After reacting under the same conditions as in Example 2, unreacted methyl acrylate was removed by vacuum distillation, and 180 g of toluene and 77 g of heptane were added to the residue.
And then 77g of 10% aqueous sodium hydroxide solution
Was added and stirred at 50 ° C. for 30 minutes. A precipitate was present in the mixture in the reaction vessel, and it took 2 hours or more to separate the precipitate by filtration. After performing the washing operation twice in total, the organic solvent layer and the aqueous layer were separated, and the organic solvent was distilled off from the organic solvent layer under reduced pressure. The zirconium content of the obtained reaction product was 40 ppm.

From the above results, in Comparative Examples 1 and 2 in which the reaction product was purified by the conventional method, a filtration step was required and the zirconium content of the reaction product was 30 to 4
In contrast to the high level of 0 ppm, in Examples 1 to 4 to which the method for removing a zirconium chelate complex of the present invention was applied, the zirconium content rate of the obtained reaction products was any, despite the simple operation of washing. It can be seen that it is as low as 10 ppm or less.

[0045]

According to the present invention, a compound soluble in a water-insoluble organic solvent is synthesized by a reaction using a zirconium chelate complex as a catalyst, and then a solution of the reaction product in a water-insoluble organic solvent is added to a weak acid of an alkali metal. The content of the zirconium chelate complex remaining in the reaction product can be markedly reduced by a simple method of washing with an aqueous solution containing a salt.

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Claims (2)

[Claims] 1. After synthesizing a compound soluble in a water-insoluble organic solvent by a reaction using a zirconium chelate complex as a catalyst, a solution of the reaction product in the water-insoluble organic solvent is washed with an aqueous solution containing a weak acid salt of an alkali metal. A method for removing a zirconium chelate complex, comprising: 2. The method for removing a zirconium chelate complex according to claim 1, wherein the reaction using the zirconium chelate complex as a catalyst is a transesterification reaction.