TW201441187A - Method for manufacturing ester compound - Google Patents

Abstract

A method for manufacturing ester compound comprises the following steps: providing a mixture containing the acid compound and the alcohol compound and carrying out the esterification reaction under the scope of the gauge pressure of -1.0 bar to 1.0 bar, wherein after the temperature during the esterification reaction process rises to 180 DEG C to 250 DEG C, the gradient depressurization is performed to make the gauge pressure reduce to -1.0 bar. Compared with previous method of manufacturing ester compound, the manufacturing method of the present invention can produce the ester compound with the yield being above 98.5%, and its processing time is short enough to conform to the industrial production benefit.

Description

Method for preparing ester compounds

The present invention relates to a process for preparing an ester compound, and more particularly to a process for preparing an ester compound by a gradient pressure reduction method.

Dioctyl terephthalate (DOTP) is a plasticizer that is an additive used to increase the softness of a material or to liquefy a material.

TW200846315A discloses a process for preparing terephthalic acid diester. The method for preparing a terephthalic acid diester comprises: contacting terephthalic acid with at least one alcohol in a reactor and in the presence of a catalyst, wherein the alcohol is a C ₆ to C ₁₀ alcohol, and the total pressure is Maintained at about atmospheric pressure, the temperature is maintained at about 150 ° C to 270 ° C, and the reactor is equipped with a fractionation column for removing water. The patent disclosed in Example 2 discloses that the yield is about 88.9% when the fractionation column is not used, and the process time is about 21.5 hours. Further, using the fractionation column in Example 3, the yield is increased to 98.5% and the process time is shortened to 9.0. hour. The patent is to increase the yield and shorten the process time through the fractionation column.

US7799942 discloses a process for preparing terephthalic acid diesters. The method for preparing a terephthalic acid diester comprises: contacting a phthalic acid with an alcohol in the presence of a catalyst in a reaction zone, wherein the alcohol comprises at least one of a C ₆ to C ₁₀ alcohol, and the total pressure is maintained at A bar gauge of about 1 to 4 bar, the temperature is maintained at about 180 ° C to 270 ° C, the molar ratio of alcohol to phthalic acid is maintained at about 2:1 to 2.5:1, and the inert gas is passed through the reaction zone. The phthalic acid/alcohol reaction mixture is used to remove a mixture of water and alcohol from the reaction zone during the preparation of the terephthalic acid diester. This patent discloses in Example 1 that the yield of the preparation process is about 88% and the process time is about 10.5 hours. The patent is to effectively remove water through inert gas to improve productivity and shorten process time.

However, although the preparation method of the patent method can shorten the process time and has a good yield, it still cannot meet the industry's demand for production efficiency. In view of the above, the preparation of the modified ester compound to provide a higher yield of the ester compound, and at the same time, to more effectively shorten the process time, is a subject that can be further broken by those skilled in the art.

Accordingly, it is an object of the present invention to provide a process for preparing an ester compound with high yield and short process time.

Thus, the method for preparing an ester compound of the present invention comprises the steps of: providing a mixture comprising an acid compound and an alcohol compound, and performing an esterification reaction at a gauge pressure ranging from -1.0 bar to 1.0 bar, wherein during the esterification reaction After the temperature was raised to 180 ° C to 250 ° C, a gradient was applied to reduce the gauge pressure to -1.0 bar.

The effect of the invention lies in: the control of the permeation pressure and the gradient The method of depressurization can increase the yield of the ester compound to over 98.5%, and the process time can be shortened to less than 7 hours, which is in line with the production efficiency of the manufacturer.

The method for preparing an ester compound of the invention comprises the following steps: Providing a mixture comprising an acid compound and an alcohol compound, and performing an esterification reaction at a gauge pressure ranging from -1.0 bar to 1.0 bar, wherein the temperature is raised to 180 ° C to 250 ° C during the esterification reaction, and then the gradient is lowered. , to reduce the gauge pressure to -1.0bar.

The method for preparing an ester compound of the invention will continue to be heated during the esterification reaction process and the gradient depressurization process. As the ester compound is gradually formed, the water formed during the esterification reaction will gradually decrease, so that the water can be taken out efficiently, and the esterification reaction can be continued. The step-down of the gradient can effectively reduce the water and the alcohol compound. It has a common boiling point and is beneficial for removing water from the esterification reaction process. In detail, the present invention performs an esterification reaction between 0 bar (gauge pressure) and 1 bar (gauge pressure), and water is gradually formed during the esterification reaction, and the temperature is continuously increased until the temperature is raised to between 180 ° C and 250 ° C. The esterification reaction is still continued. At this time, the gradient pressure is reduced and the pressure is lowered to -1.0 bar (gauge pressure), and the heating is continued to avoid the pressure drop and the temperature is lowered, and at the same time, during the esterification reaction. The generated water is removed by gradient decompression and can be removed more efficiently.

Preferably, the alcohol compound is used in an amount ranging from 2.1 moles to 3.0 moles, based on the total amount of the acid compound of 1 mole.

Preferably, the acid compound is a monobasic acid selected from C ₄ to C ₁₀ , a C ₄ to C ₁₀ polybasic acid, or a combination thereof.

Preferably, the C ₄ to C ₁₀ monobasic acid is selected from the group consisting of n-butyric acid, isobutyric acid, n-pentanoic acid, and n-heptanoic acid (n). -heptanoic acid), 2-methylhexanoic acid, 2-ethylhexanoic acid, n-nonanoic acid, isonic acid, 癸Decanoic acid, or a combination of these.

Preferably, the C ₄ to C ₁₀ polybasic acid is selected from the group consisting of terephthalic acid, succinic acid, glutaric acid, adipic acid, Suberic acid, azelaic acid, maleic acid, fumaric acid, citric acid, phthalic acid, Isophthalic acid, trimellitic acid, pyromellitic acid, or a combination thereof.

Preferably, the alcohol compound is a monohydric alcohol selected from C ₄ to C ₁₀ , a C ₄ to C ₁₀ polyhydric alcohol, or a combination thereof.

Preferably, the C ₄ to C ₁₀ monohydric alcohol is selected from the group consisting of 2-ethylhexanol, n-butanol, isobutanol, and pentanol. , hexanol, heptanol, isononol, 2-propylheptanol, decanol, or a combination thereof.

Preferably, the C ₄ to C ₁₀ polyol is selected from the group consisting of ethylene glycol, 1,2-propylene glycol, and 1,3-propane. Diol), 1,4-butane diol, 1,3-butane diol, 1,6-hexanediol 1,10-decane diol, diethylene glycol, triethylene glycol, pentaerythritol, or a combination thereof.

Preferably, the mixture further comprises a catalyst.

Preferably, the catalyst is used in an amount ranging from 0.01% by weight to 1.0% by weight based on 100% by weight of the total of the mixture.

Preferably, the catalyst is selected from a titanium-based catalyst, a tin-based catalyst or a sulfonic acid-based catalyst.

Preferably, the titanium-based catalyst is selected from the group consisting of tetraisopropoxytitanate, titanium tetrabutoxide, titanium tetraethoxide, or a combination thereof.

Preferably, the tin-based catalyst is selected from the group consisting of tin tetraethoxide, dimethyltin aceate, tin oxide, and dibutyltin oxide. Tin(II) oxide, tin(II)oxalate, or a combination thereof.

Preferably, the sulfonic acid catalyst is selected from the group consisting of sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, or a combination thereof.

The invention is further described in the following examples, but it should be understood that these examples are for illustrative purposes only and are not to be construed as limiting.

[Comparative Example 1]

Under normal pressure, 250 g of terephthalic acid and 430 g of 2-ethylhexanol were put into a reactor having a stirrer and a temperature-controlled heater with a capacity of 1,000 ml, and then 0.2 g of four different was added. Titanium propoxide.

Start the stirrer and the temperature control heater, and carry out the esterification reaction under normal pressure (gauge pressure 0 bar). When heated to about 170 ° C, a small amount of water and 2-ethylhexanol are mixed and vaporized, and the esterification reaction proceeds. a large amount of mixed vapor of water and 2-ethylhexanol is gradually produced, and the mixed vapor is introduced into a water separator to separate and recover 2-ethylhexanol, and the recovered 2-ethylhexanol is continuously refluxed to the reaction. In the device. The temperature is continuously increased during the esterification reaction, and finally, until the absence of water in the oil-water separator, the end of the esterification reaction is reached, the esterification reaction is terminated at a temperature of about 250 ° C, and the total esterification reaction time is about 11 hours. The conversion rate was 96%. Next, the crude product is further subjected to a neutralization treatment, a water washing treatment, a dealcoholization treatment, and a decolorization treatment to obtain dioctyl terephthalate having a purity of more than 99.5%. The calculation of the conversion rate: [actual water production amount (g) / theoretical water production amount (g)] × 100%.

[Example 1]

250 g of terephthalic acid and 430 g of 2-ethylhexanol were introduced into a reactor with a stirrer and a temperature-controlled heater at a pressure of 1000 bar under normal pressure (gauge pressure 0 bar), and then added 0.2 g of titanium tetraisopropoxide.

Start the stirrer and the temperature control heater, and carry out the esterification reaction under the gauge pressure of 0.99 bar. When heated to about 150 ° C, a small amount of water and 2-ethylhexanol are mixed and vaporized. As the esterification reaction proceeds, it gradually produces. Large amount of water with 2-ethyl The mixed vapor of hexanol is introduced into a water separator to separate and recover 2-ethylhexanol, and the recovered 2-ethylhexanol is continuously refluxed to the reactor. During the esterification reaction, the temperature is continuously increased. When the reaction temperature reaches 205 ° C, the gradient is reduced and the pressure is reduced to -0.99 bar. At the same time, the temperature is continuously increased during the depressurization process, and finally, until the oil and water are separated. In the presence of anhydrous in the apparatus, the end of the esterification reaction was reached, the esterification reaction termination temperature was about 250 ° C, the total esterification reaction time was about 6.5 hours, and the conversion rate of the crude product was 98.65% (see Table 1). Next, the crude product is further subjected to a neutralization treatment, a water washing treatment, a dealcoholization treatment, and a decolorization treatment to obtain dioctyl terephthalate having a purity of more than 90.5%.

In Comparative Example 1, the esterification reaction was carried out under normal pressure (gauge pressure: 0 bar), and the water was removed by heating to facilitate the esterification reaction, but the manner of removing the water by heating would cause the entire process time to be pulled. Long, not in line with production efficiency. In the first embodiment, the esterification reaction was carried out at a gauge pressure of 0.99 bar, and the pressure was lowered by a gradient to effectively remove water, which in turn reduced the reaction time.

In summary, the control of the pressure and the step of reducing the pressure of the gradient can increase the yield of the ester compound to 98.5% or more, and at the same time, shorten the process time, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the patent application scope and patent specification content of the present invention, All remain within the scope of the invention patent.

Claims (7)

A method for preparing an ester compound, comprising the steps of: providing a mixture comprising an acid compound and an alcohol compound, and performing an esterification reaction at a gauge pressure ranging from -1.0 bar to 1.0 bar, wherein the temperature rises during the esterification reaction After 180 ° C to 250 ° C, a gradient was applied to reduce the gauge pressure to -1.0 bar. The method for producing an ester compound according to claim 1, wherein the acid compound is a monobasic acid selected from C ₄ to C ₁₀ , a C ₄ to C ₁₀ polybasic acid, or a combination thereof. The method for producing an ester compound according to claim 1, wherein the alcohol compound is a monohydric alcohol selected from C ₄ to C ₁₀ , a C ₄ to C ₁₀ polyhydric alcohol, or a combination thereof. The method of preparing an ester compound according to claim 1, which further comprises a catalyst. The method for producing an ester compound according to claim 4, wherein the catalyst is selected from a titanium-based catalyst, a tin-based catalyst or a sulfonic acid-based catalyst. The method for producing an ester compound according to claim 1, wherein the alcohol compound is used in an amount ranging from 2.1 mol to 3.0 mol, based on the total amount of the acid compound of 1 mol. The method for producing an ester compound according to claim 4, wherein the catalyst is used in an amount ranging from 0.01% by weight to 1.00% by weight based on 100% by weight of the total of the mixture.