JPH06279364A - Production of ester - Google Patents

Abstract

PURPOSE:To provide an industrially advantageous method for producing an ester in which the operation is simple and by which the high-quality ester is obtained. CONSTITUTION:This method for producing an ester is to subject an organic acid or its anhydride and an alcohol to esterifying reaction in the presence of a catalyst of an organometallic compound, produce an esterification product and remove the catalyst in the resultant product. The method is characterized by carrying out the treatment for removing the catalyst in the esterification product with an amino compound and/or an ammonium salt of a weak acid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ester, and more particularly to a method for industrially producing an ester of high quality.

[0002]

2. Description of the Related Art Conventionally, acid catalysts such as sulfuric acid and paratoluenesulfonic acid have been used for the production of esters of organic acids or their anhydrides with alcohols. A dehydration esterification method using an organometallic compound such as isopropyl titanate, tetrabutyl titanate and tetra-2-ethylhexyl titanate as a catalyst has become widely known. When the organometallic compound is used as a catalyst, the purification method includes a wet method and a dry method.

In the wet method, for example, water is added to the reaction product,
A step of heating to hydrolyze the catalyst, neutralize unreacted organic acid or reaction intermediate acid with an alkali, and wash with water to obtain a crude ester, which is then subjected to steam distillation and vacuum distillation, followed by purification with activated carbon, activated clay or the like. (JP-A-55-130937)
(See the official gazette). And the dry method is carried out, for example, in the step of treating the reaction product with a solid alkali such as sodium carbonate by heating or simultaneously with the step of treating with an adsorbent such as activated clay (see JP-A-54-76517). ).

[0004]

However, the operation of the above-mentioned wet method is complicated and the heat loss due to the rise and fall of the temperature during purification, the consumption of alkali and washing water,
There are problems such as increased load on wastewater treatment. And since the dry method described above is a solid-liquid reaction, the reaction efficiency is poor,
There is a problem that the amount of solid alkali is required in a large amount as compared with the equivalent amount while being at high temperature for a long time.

Therefore, the object of the present invention is to eliminate the above-mentioned problems of the conventional method, to be easy to operate and industrially advantageous,
Another object of the present invention is to provide a method for producing an ester capable of obtaining a high-quality ester.

[0006]

In order to achieve the above-mentioned object, the inventors of the present invention have earnestly studied, and as a result, have achieved good results and completed the present invention.

That is, in the present invention, in the presence of a catalyst of an organometallic compound, an organic acid or its anhydride is subjected to an esterification reaction with an alcohol to produce an esterification product, and the catalyst in the product is removed. To produce an ester, characterized in that the removal of the catalyst in the esterification product is treated with an amino compound and / or a weak acid ammonium salt.

The esterification reaction is carried out at a temperature of 180 ° C. or higher. Therefore, examples of the catalyst of the organometallic compound include alkyl titanates which show catalytic activity at a temperature of 180 ° C. or higher. For example, tetraisopropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate and the like are used.

The above-mentioned organic acids or their anhydrides are aromatic polycarboxylic acids such as phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid, trimellitic acid, trimellitic anhydride and pyromellitic acid; adipic acid and sebacine. Acids, azelaic acid, and other aliphatic polycarboxylic acids; maleic acid, fumaric acid, and other aliphatic unsaturated polycarboxylic acids; oleic acid, stearic acid, and other aliphatic monocarboxylic acids; benzoic acid, and other aromatic monocarboxylic acids Acid etc. are mentioned. Examples of alcohols used in the production of esters with these organic acids include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, secondary butyl alcohol, isoheptyl alcohol, n-. Aliphatic saturated monohydric alcohols such as octyl alcohol, 2-ethylhexyl alcohol, isooctyl alcohol, decanol, isodecyl alcohol, undecanol and tridecanol; Aliphatic polyhydric alcohols such as ethylene glycol, diethylene glycol and propylene glycol; Aroma such as benzyl alcohol Group monohydric alcohols may be mentioned, and these alcohols may be mixed and used.

The reaction of an organic acid or its anhydride with an alcohol in the presence of an organometallic compound catalyst is carried out in the same manner as in the conventional case.
It can be carried out by a dehydration esterification reaction. An esterification product is obtained by a dehydration esterification reaction. Since the esterification product contains impurities such as a catalyst, an amino compound and / or a weak acid ammonium salt is used in the present invention for the removal treatment of the impurities.

Examples of amino compounds are aliphatic amino compounds such as butylamine, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, 2-dimethylaminoethanol and piperazine, and aromatic amino compounds such as aminophenol and phenylenediamine. Nitrogen-containing heterocyclic compounds such as pyrrole, imidazole and pyridine; amides such as acetamide, formamide, benzamide, urea, thiourea, dimethylurea and melamine. Examples of the weak acid ammonium salt include ammonium carbonate, ammonium hydrogen carbonate, ammonium acetate and the like.

The amount of the amino compound and / or the weak acid ammonium salt used is related to the amount of the metalorganic compound catalyst used and the metal valence, and is related to the number of nitrogen atoms of the amino compound and / or the weak acid ammonium salt. , S (calculation amount) shown by the following equation (I) or more. The optimum amount of use is 1 to 10 times that of S represented by the following formula (I), but is not limited to this multiple. If the amount of the amino compound and / or ammonium salt of weak acid used is less than 1 time, the effect of removing the catalyst is not sufficient, and if it exceeds 10 times, the surplus becomes disadvantageous in terms of cost. The surplus does not contribute to the removal of the catalyst, but does not cause a quality problem in the ester produced by the surplus.

The amount of the amino compound and / or the weak acid ammonium salt used is Is calculated based on. However, in the above formula (I), A: the amount of the catalyst of the organometallic compound used, B: the valence of the metal of the catalyst of the organometallic compound, M: the molecular weight of the catalyst of the organometallic compound, m: of the amino compound and / or weak acid ammonium salt. Molecular weight n: Amino compound and / or weak acid ammonium salt 1
It is the number of nitrogen atoms contained in the molecule.

Since the product of the esterification reaction contains the catalyst, the catalyst is removed by using the amino compound and / or the weak acid ammonium salt. In this removal treatment, the esterification product obtained by distilling off the excess alcohol after the esterification reaction is added and mixed with the amino compound and / or the weak acid ammonium salt in an amount equal to or more than the calculated amount of the above formula (I) to effect esterification. Below the temperature, preferably 160
160 ℃ after holding for 5 minutes or more above ℃ and below 180 ℃
The catalyst and the acid component are removed as a solid by filtration below, preferably at 120 ° C. or less, to obtain a high-quality ester (ester compound). It should be noted that a higher quality ester can be obtained by treating with an adsorbent such as activated carbon and a deoxidizer in combination.

[0015]

The produced esterification product contains a catalyst. The catalyst in this product is reacted with an amino compound and / or a weak acid ammonium salt to remove the catalyst. That is, the catalyst in the esterification product is the amino compound and / or
Alternatively, it becomes a compound that has reacted with a weak acid ammonium salt and can be removed as a solid. The acid component in the esterification product can also be removed as a solid by the amino compound and / or the weak acid ammonium salt. The amount of amino compound and / or weak acid ammonium salt used for removing the catalyst is used based on S calculated in the formula (I).

[0016]

EXAMPLES Next, examples and comparative examples of the present invention will be described. Example 1 148 g (1.0 mol) of phthalic anhydride and 312 g (2.4 mol) of 2-ethylhexyl alcohol were mixed, and 0.17 g (0.00 mol) of tetraisopropyl titanate was mixed therein.
(06 mol) was added, and dehydration esterification reaction was carried out with stirring and heating at 180 ° C. to 220 ° C. for 3 hours. 5-40m after reaction
Excessive 2-ethylhexyl alcohol was distilled off under reduced pressure of mHg to obtain a product of the esterification reaction. 0.072 g (0.0012 mol) of urea was added to the product of this esterification reaction, the mixture was stirred at 170 ° C. for 5 minutes, cooled to 100 ° C., 0.2 g of aluminum oxide and 0.2 g of activated carbon were added, and the mixture was filtered. Di2-ethylhexyl phthalate (hereinafter,
Abbreviated as DOP. ) Got. JIS of the obtained DOP
Acid value and volume resistivity (liquid VR) according to K6751
The hue and the titanium content are as shown in Table 1 below, and those of the DOP obtained by the conventional method (Comparative Example described later) (Table 5
The value is equal to or higher than that of the reference).

[0017]

Example 2 148 g (1.0 mol) of phthalic anhydride and 312 g (2.4 mol) of 2-ethylhexyl alcohol were mixed, to which 0.20 g (0.0006 mol) of tetrabutyl titanate was added, The dehydration esterification reaction was carried out with stirring and heating at 180 to 220 ° C. for 3 hours. After the reaction, excess 2-ethylhexyl alcohol was distilled off under reduced pressure of 5 to 40 mmHg to obtain a product of esterification reaction. Hexamethylenediamine 0.27 g (0.00
24 mol), and after stirring at 170 ° C. for 5 minutes, 100
C., 0.2 g of aluminum oxide and 0.
2 g was added and filtered to obtain DOP. The properties of the obtained DOP are as shown in Table 2.

[0019]

Example 3 By the method of Example 1, phthalic anhydride and 2-ethylhexyl alcohol were subjected to dehydration esterification reaction using tetraisopropyl titanate as a catalyst. After the reaction, excess 2-ethylhexyl alcohol was distilled off to obtain a product of the esterification reaction. 0.12 g (0.0018 mol) of imidazole was added to the product of this esterification reaction, and the mixture was stirred at 180 ° C. for 10 minutes.
I got OP. The properties of the obtained DOP were as shown in Table 3.

[0021]

Example 4 By the method of Example 2, phthalic anhydride and 2-ethylhexyl alcohol were subjected to dehydration esterification reaction using tetrabutyl titanate as a catalyst, and after the reaction, excess 2-ethylhexyl alcohol was distilled off. The product of the esterification reaction was obtained. To the product of this esterification reaction was added ammonium carbonate 0.34 g (0.0035 mol) to give 160
The mixture was stirred at 0 ° C for 10 minutes to obtain DOP in the same manner as in Example 1 below.
The properties of the obtained DOP are as shown in Table 4.

[0023]

Comparative Example 148 g (1.0 mol) of phthalic anhydride and 312 g (2.4 mol) of 2-ethylhexyl alcohol were mixed, and 0.17 g (0.000) of tetraisopropyl titanate was mixed with this.
(06 mol) was added, and dehydration esterification reaction was carried out with stirring and heating at 180 ° C. to 220 ° C. for 3 hours. Cool down this product,
Add 50 g of water and 2.0 g of sodium carbonate, add 100
The mixture was neutralized at 30 ° C. with stirring for 30 minutes, liquid-separated to remove the aqueous layer, and the product was washed twice with the same amount of water. After removing the aqueous layer, the temperature was raised to 2 by vacuum distillation. -Ethylhexyl alcohol was distilled off, and the mixture was cooled to 100 ° C.
DOP was obtained by adding 2 g and activated carbon 0.2 g and filtering. The properties of the obtained DOP were as shown in Table 5.

[0025] It was confirmed that each of the esters obtained in Examples 1 to 4 described above had a high quality equivalent to or higher than that of the ester of Comparative Example.

[0026]

According to the present invention, the reaction in the presence of a catalyst is the same as in the conventional case, and if the esterification reaction product is treated with an amino compound and / or a weak acid ammonium salt,
Since the catalyst contained in the reaction product is easily removed,
The operation is simpler than the conventional method, which is industrially advantageous. Further, according to the present invention, the removal of the catalyst in the esterification product is treated with an amino compound and / or an ammonium salt of a weak acid, so that a high-quality ester free from the catalyst can be obtained. The present invention has an advantage that the wastewater treatment load can be greatly reduced since the amount of wastewater is smaller than that of the conventional method.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location // C07B 61/00 300 (72) Inventor Hisao Uchino 507-2 Shinhocho, Tokai City, Aichi Prefecture Toho Gas Incorporated Technology Research Institute

Claims (1)

[Claims] 1. An esterification reaction of an organic acid or its anhydride with an alcohol in the presence of a catalyst of an organometallic compound to produce an esterification product. The catalyst in the product is removed to remove the ester. A method for producing an ester, which comprises treating the removal of the catalyst in the esterification product with an amino compound and / or an ammonium salt of a weak acid.