KR20040073733A - The Purification Method of High Purity Glycol Diesters By the Effective Removal of the Catalyst - Google Patents

Abstract

PURPOSE: A method for purifying glycol diester is provided to prevent product loss and change of color during a product isolation process by effectively removing a titanate catalyst, and therefore to produce the glycol diester product with high purity in a stable way. CONSTITUTION: The method for purifying glycol diester that is carried out after completing the synthesis of glycol diester with glycol monoester, aliphatic carboxylic acid and a titanate catalyst, comprises: carrying out phase separation of the resulted product into an aqueous phase and an organic phase with an aqueous sodium hydroxide solution; hydrolyzing the residual catalyst present in the aqueous phase; filtering out the residual catalyst present in the organic phase; and separating glycol diester through a low temperature distillation column for compounds having a lower boiling point compared to glycol ester, and a high temperature distillation column for compounds having a higher boiling point compared to glycol ester.

Description

Purification Method of High Purity Glycol Diesters By the Effective Removal of the Catalyst

The present invention relates to a process for purifying glycol diesters. More specifically, in the process of preparing glycol diester using a titanate catalyst using glycol monoester and aliphatic carboxylic acid as raw materials, the reaction product is utilized from hydrolysis and filtration using sodium hydroxide aqueous solution. The present invention relates to a method for purifying a glycol diester which stably purifies a glycol diester of high purity by effectively removing the titanate-based catalyst.

Glycol diesters are used as floor coverings and plasticizers for toys, and are widely used in various products such as vinyl glove and coating products. Glycol monoester and aliphatic carboxylic acid can be synthesized by various methods. Glycol diester can be prepared by esterification using a titanate catalyst as a raw material. However, titanate catalysts used in the ester reaction, such as tetra isopropyl titanate, tetra normal butyl titanate, tetra 2-ethylhexyl titanate, etc., are uniformly dissolved in the reaction product when the reaction is completed, making it difficult to separate them. do.

As such, when the catalyst used in the reaction remains in the reaction product, side reactions are induced during the distillation process to purify the product, causing discoloration of the product with the loss of the product, and the reaction cannot be stably maintained. Therefore, in general, when the reaction is completed, it is necessary to remove the catalyst used in the reaction from the reaction product through various methods. To solve this problem, conventional techniques use a non-uniform catalyst in which the reaction catalyst is a solid phase, There are methods characterized by easy separation from the catalyst, but the use of a non-uniform catalyst has the disadvantage that the conversion of the reaction and the selectivity of the product is lower than when using a homogeneous catalyst. Therefore, in order to increase the conversion and selectivity of the reaction using a homogeneous catalyst, a method of effectively removing the catalyst used in the reaction from the reaction product must first be secured. Related prior arts include the following.

U.S. Patent No. 5,138,092 discloses a process for producing butyl acrylate through ester reaction using acrylic acid, 1-butene and a non-uniform reaction catalyst, which is fixed by using a non-uniform catalyst. Since the reaction product is produced as the reactant passes through the catalyst layer, there is no separate process for separating the catalyst, while the reaction yield of the final product butyl acrylate is low as 85 percent.

In Japanese Patent Laid-Open No. 54-46708, dibutyl tin oxide is used as a reaction catalyst, and 2,2,4-trimethyl-1,3-pentanediol, 2,2,4-trimethyl-1,3- A process for preparing 2,2,4-trimethyl-1,3-pentanediol diisobutyrate using four raw materials, such as pentanediol monoisobutyrate and isobutyl isobutyrate, is disclosed, wherein the catalyst from the reaction product It was shown that the reaction product was washed with water as a method to remove the water, and after washing, the sample was found to separate 2,2,4-trimethyl-1,3-pentanediol diisobutyrate through vacuum distillation. . This process is characterized by a simple process using only washing as a method of removing the catalyst from the reaction product, but yielding 2,2,4-trimethyl-1,3-pentanediol diisobutyrate by using dibutyl tin oxide as the reaction catalyst. The downside was that it was rather low at 85 percent.

In German Patent No. 3,102,826, the catalyst was removed from the reaction product by adding 10% sulfuric acid after completion of the primary reaction using 33% sodium hydroxide as the reaction catalyst using isobutylaldehyde as a raw material. Isobutyric acid was newly added to the reaction product from which the catalyst was removed, and a second reaction was performed using p-toluene solphonic acid as a reaction catalyst, and sodium hydroxide carbonate was added to remove the catalyst from the reaction product. The reaction product was completed using a distillation column to separate the final product 2,2,4-trimethyl-1,3-pentanediol diisobutyrate. However, here, the selectivity for the final product, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, was low at 78 percent, and the reaction was separated first and second, so that two catalysts were used. The catalyst removal process also had the disadvantage of requiring twice.

In U.S. Patent No. 5,180,847, when the reaction is completed using isobutylaldehyde as a raw material and 1% sodium hydroxide as a reaction catalyst, unreacted isobutylaldehyde, a reaction product, and sodium isobutyrate salt, another form of catalyst, In this case, the reaction mixture was directly supplied to the distillation column without removing the reaction catalyst, and the reaction of the unreacted isobutylaldehyde was further performed with the separation of the product. The final product was 23% 2,2,4-trimethyl-1,3-pentanediol, 28% 2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl- 1,3-pentanediol diisobutyrate was 49 percent. This technology has the characteristic of obtaining three products at the same time, but the reaction occurs continuously due to the presence of a catalyst during the separation process, so that the ratio of the final product varies greatly depending on the separation conditions and if the desired product is one The product had a low selectivity.

As described above, since the yield of the final product is determined by the method of removing the reaction catalyst from the reaction product along with the selection of the reaction catalyst in the production process of glycol diester, a study on the effective method of removing the catalyst from the reaction product Was desperately required.

In order to solve the above problems, the present invention, in the process of preparing a glycol diester represented by the following formula (3) using the glycol monoester represented by the formula (1) and the aliphatic carboxylic acid represented by the formula (2) as a raw material Glycol, which can effectively remove the titanate-based catalyst from the reaction product through hydrolysis and filtration at optimum conditions using aqueous sodium hydroxide solution and separate high-purity glycol diester under reduced pressure using distillation column It is an object to provide a method for purifying diester.

HO-R ¹ -OC (= O) -R ²

R ³ -C (= O) -OH

R ³ -C (= O) -OR ¹ -OC (= O) -R ²

Wherein R ¹ is C ₁ ~ C ₁₆ alkylidene of (alkylidene) group and R ² is C ₁ ~ C ₁₆ alkyl (alkyl) groups, and the R ³ is an alkyl (alkyl) group, a C ₃ ~ C _16.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention,

In the method of synthesizing a glycol diester using a titanate catalyst using a glycol monoester and an aliphatic carboxylic acid as a raw material, the method of purifying the glycol diester comprises using an aqueous sodium hydroxide solution to form a reaction product with the organic layer. A separation step of separating the layers into an aqueous layer; Hydrolyzing the catalyst remaining in the aqueous layer; A filtration step of removing a trace amount of catalyst remaining in the organic layer; And a separation step of separating the glycol diester through a low boiling point distillation column that removes lower boiling point substances than the glycol diester and a high boiling point distillation column that removes the higher boiling point substances than the glycol diester. It provides a purification method.

The concentration of the sodium hydroxide aqueous solution may be 2 to 70%, the hydrolysis temperature is carried out under the conditions of 20 to 100 ℃, the reaction time may be 10 to 120 minutes.

In the filtration step, one or more selected from the group consisting of activated carbon, clay and diatomaceous earth may be added and filtered.

The low boiling point distillation column and the high boiling point distillation column pressure conditions are performed at both columns 10 to 100 mbar, wherein the temperature of the column bottom may be 180 to 230 ℃ both columns.

Hereinafter, the present invention will be described in detail.

The raw materials used in the experiments are aliphatic carboxylic acids and glycol monoesters, and tetraisopropyl titanate is used as a catalyst to synthesize glycol diesters. When the reaction is completed, the reaction product and the catalyst are present in a uniform dissolved state inside the reactor.

In the present invention, the sodium hydroxide aqueous solution is used to hydrolyze the sample after the reaction is completed, wherein the concentration of the aqueous solution is 2 to 70% suitable for use in the aqueous solution in a commercial process, more preferably 5 to 50% It is good.

The hydrolysis temperature is suitably 20 to 100 ° C., more preferably at 30 to 80 ° C. conditions. If the temperature exceeds 100 ℃ is not suitable because the water contained is boiling, if the temperature is less than 20 ℃ is not preferable because the reaction hardly occurs.

The reaction time is preferably 10 to 120 minutes, more preferably 30 to 60 minutes. When the reaction time exceeded 120 minutes, no further hydrolysis occurred, and when the reaction time was less than 10 minutes, the hydrolysis did not sufficiently occur.

In the present invention, when the organic layer and the aqueous layer are formed by hydrolysis, most of the titanate salts dissolved in the aqueous layer are removed by layer separation, and then the pore sizes of the titanate salt and sodium hydroxide salt remaining in the organic layer are suitably. Preference is given to using a filter of 0.1 to 20 mu m, more suitably 5 to 10 mu m.

In the present invention, the titanate content is 1 ppm or less in the organic layer after the filtration process, and a certain amount of white clay or diatomaceous earth may be added to increase the efficiency in the filtration process, or a certain amount of activated carbon may be added to improve the color of the product.

In the present invention, in order to obtain a glycol diester content of at least 99.5% by weight, a low boiling point distillation column which removes lower boiling point substances than glycol diester and a high boiling point distillation column which removes higher boiling point substances than glycol diester are used. The distillation apparatus used for a distillation method can use the distillation apparatus normally used as a multistage distillation apparatus.

The pressure conditions of the distillation column in the present invention is carried out at both columns, suitably 10 to 100 mbar, more suitably 30 to 80 mbar, wherein the temperature conditions at the bottom of the column are both columns, suitably 180 to 230 ° C More preferably, 200-210 degreeC is preferable. If the pressure of the column is below 30 mbar, vapor load increases in the column, making it difficult to separate the product.In the case of more than 80 mbar, the temperature at the bottom of the column must be increased to 230 ° C. or higher. do.

The present invention is explained in more detail with reference to the following examples and comparative examples. However, these examples are only for illustrating the present invention, but the present invention is not limited thereto.

Example 1

171.3 g of isobutyric acid, 324.4 g of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and 3.25 g of tetra isopropyl titanate were added to the reactor, and the reaction was performed under reflux at a reaction temperature of 230 ° C. The reaction was carried out for 6 hours. When the unreacted isobutyric acid was recovered by evaporation, 430 g of the reaction product remained in the reactor, and 83 g of a 5% sodium hydroxide aqueous solution was mixed with the reaction product, followed by hydrolysis at 70 ° C. for 30 minutes to form an organic layer and an aqueous layer. It was confirmed to form. After removing the aqueous layer in which the titanate salt was dissolved, the remaining organic layer was filtered using a filter having a pore size of 5 μm. After the filtration, the titanate content in the reaction product was removed to 1 ppm or less. Appeared.

Example 2

The material obtained in Example 1 was used as a feed for a low boiling point distillation column to remove low boiling point materials, using a 25 column Oldershaw column with a diameter of 50 mm, the nozzle position of the feed at 14 stages, and a pressure of 80 mbar, The feed was flowed at a flow rate of 8.5 g per minute at a temperature of 203 ° C. at the bottom of the column and 8.4 g of sample was extracted at the top of the column at the bottom, where 2,2,4-trimethyl-1,3-pentanediol was used. Diisobutyrate content was obtained at 99.0% by weight. The material separated at the bottom of the low boiling distillation column was used as a feed for the high boiling distillation column, and the nozzle position of the feed was set at 20 stages using a 25 column Oldershaw column with a diameter of 50 mm and a pressure of 30 mbar, At a temperature of 200 ° C at the bottom of the column, the feed was flowed at a flow rate of 6.8 g per minute and a sample of 6.7 g per minute was taken out to the top of the tower, where 99.6% by weight of 2,2,4-trimethyl-1,3 was taken to the top. -Pentanediol diisobutyrate could be obtained. At this time, there was no loss of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate in the process of separating using a distillation column, and the APHA color of the final product was 3 after the high boiling point distillation column.

Example 3

The experiment was conducted in the same manner as in Example 1, except that 10 g of activated carbon, clay, and diatomaceous earth were added to the reaction product, respectively, before the filtration was performed in Example 1. Under these conditions, the content of titanate in the reaction product was removed below 1 ppm, and the APHA color of the reaction product was 40.

Example 4

The experiment was carried out in the same manner as in Example 1, except that 8.3g of 50% aqueous sodium hydroxide solution was added in the hydrolysis step in Example 1 and the temperature was advanced at 30 ° C. Under these conditions, the titanate content in the reaction product was removed below 1 ppm and the APHA color of the reaction product was 200.

Comparative Example 1

After the reaction was completed under the same conditions as in Example 1, the distillation was carried out using the same conditions as in Example 2 without performing hydrolysis and filtration, and the titanate content in the reaction product was found to be 1250 ppm. 2,2,4-trimethyl-1,3-pentanediol diisobutyrate was found to decrease 2.1% by weight based on the initial supply during the separation process through the low boiling point distillation column and the high boiling point distillation column. The APHA color of the final product after distillation column was 400.

Comparative Example 2

After the reaction was carried out under the same conditions as in Example 1, 400 g of pure distilled water was added, and hydrolysis was performed for 30 minutes. As a result, layer separation between the organic layer and the aqueous layer did not occur, and thus it was difficult to remove the catalyst from the reaction product.

As can be seen in the above examples and comparative examples, by removing the catalyst to less than 1ppm through the purification method of the glycol diester according to the present invention to prevent discoloration of the product by the catalyst remaining in the purification process is excellent in color and high purity It turned out that the glycol diester of can be obtained.

As described above, the purification method of the glycol diester according to the present invention effectively removes the titanate-based catalyst used in the synthesis to prevent product loss and discoloration in the process of separating the final product, and to stabilize the product of high purity It is a useful invention that can be separated into effects.

While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.

Claims (5)

In the method of refine | purifying a glycol diester after synthesize | combining glycol diester using a titanate-type catalyst using glycol monoester and aliphatic carboxylic acid as a raw material, A separation step of separating the reaction product into an organic layer and an aqueous layer using an aqueous sodium hydroxide solution; Hydrolyzing the catalyst remaining in the aqueous layer; A filtration step of removing a trace amount of catalyst remaining in the organic layer; And A separation step of separating the glycol diester through a low boiling point distillation column to remove lower boiling point substances than glycol diester and a high boiling point distillation column to remove higher boiling point substances than glycol diester; Purification method. The method of claim 1, The concentration of the aqueous sodium hydroxide solution is 2 to 70%, characterized in that the purification method of the glycol diester. The method of claim 1, The hydrolysis temperature is carried out under the conditions of 20 to 100 ℃, the reaction time is a purification method of glycol diester, characterized in that 10 to 120 minutes. The method of claim 1, In the filtration step, at least one member selected from the group consisting of activated carbon, clay and diatomaceous earth is added and filtered. The method of claim 1, The low boiling point distillation column and the high boiling point distillation column pressure conditions are carried out in both columns 10 to 100 mbar, wherein the column bottom temperature conditions are both columns 180 to 230 ℃ purifying method of the glycol diester.