JP2000290222A - Production of pure phenylenedioxydiacetic acids - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing pure phenylenedioxydiacetic acids at a high purity and in a high yield. SOLUTION: This process for producing a pure phenylenedioxydiacetic acid of the formula (R is a halogen, a carboxylic acid group or a <=4C hydrocarbon group; n is an integer of 0-3) comprises the acid precipitation of an alkaline aqueous solution of a crude phenylenedioxydiacetic acid mainly composed of phenylenedioxydiacetic acid with a mineral acid and subsequent holding of the mixture at a high temperature. In the process, 10 wt.% or more of phenylenedioxydiacetic acid is precipitated with an acid at a temp. of 0-50 deg.C from the alkaline aqueous solution of the crude phenylenedioxydiacetic acid, and the mixture is held at a temp. of 80-110 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing purified phenylenedioxydiacetic acids.

[0002]

2. Description of the Related Art The following general formula (I) (In the formula, R represents a halogen, a carboxy group or a hydrocarbon group having 4 or less carbon atoms, and n represents an integer of 0 to 3.)
Are industrially useful compounds used as raw materials such as polyesters and polyamides. As a method for producing purified phenylenedioxydiacetic acids, there is known a method in which an alkaline aqueous solution of crude phenylenedioxydiacetic acids containing phenylenedioxydiacetic acids as a main component is precipitated. For example, after acid precipitation at 80 ° C. or higher using the above-mentioned alkaline aqueous solution and mineral acid,
A method of keeping the temperature above ℃ has been proposed (JP-A-4-1737).
No. 64). However, according to this method, the obtained purified phenylenedioxydiacetic acids are not sufficiently satisfactory in terms of purity and the like, and improvement in this point has been desired.

[0003]

Under these circumstances, the present inventors have attempted to find a method for producing purified phenylenedioxydiacetic acids which provides high purity and high yield. As a result of intensive studies on the method of acid precipitation of an aqueous alkali solution, the acid precipitation was carried out at 0 to 50 ° C.
By keeping the temperature at １１０110 ° C., it was found that the objective purified phenylenedioxydiacetic acids could be obtained in high purity and high yield. If at least 10% by weight or more of the entire alkali aqueous solution of diacetic acids is acidified out, the remainder is similarly high in purity even when acidified out at a temperature other than the above temperature.
The present inventors have found that the desired product can be obtained in high yield, and have completed the present invention.

That is, the present invention provides a compound represented by the following general formula (I) (Wherein R represents a halogen, a carboxy group or a hydrocarbon group having 4 or less carbon atoms, and n represents an integer of 0 to 3). In a method for producing purified phenylenedioxydiacetic acids by subjecting an alkaline aqueous solution of oxydiacetic acids to acid precipitation with a mineral acid and keeping the temperature, at least 10% by weight of the aqueous alkali solution of crude phenylenedioxydiacetic acids is reduced to 0%. Acid precipitation at ~ 50 ° C, keeping the temperature at 80 ~ 110 ° C
And a method for producing purified phenylenedioxydiacetic acids.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Examples of the phenylenedioxydiacetic acids in the present invention include compounds represented by the above general formula (I). Here, as the substituent R, a halogen atom such as fluorine, chlorine, and bromine, a carboxy group or a salt thereof, methyl, ethyl,
Examples thereof include a hydrocarbon group having about 1 to 4 carbon atoms, such as a t-butyl group. In addition, n is an integer of about 0 to 3, preferably 0.

[0006] The crude phenylenedioxydiacetic acids which are the raw materials of the present invention contain the above-mentioned phenylenedioxydiacetic acids (I) as a main component. The content of the phenylenedioxydiacetic acids (I) in the crude phenylenedioxydiacetic acids is usually about 80% by weight or more, particularly preferably about 90% by weight or more as a solid content.

[0007] The alkaline aqueous solution of the crude phenylenedioxydiacetic acids may be an alkaline aqueous solution containing phenylenedioxydiacetic acids (I) as a main component. A slurry in which diacetic acids (I) and the like are precipitated may be used. The method for producing the aqueous alkali solution of the crude phenylenedioxydiacetic acids is not particularly limited. For example, the following general formula (II) (Wherein, R and n have the same meanings as described above), by reacting dihydroxybenzenes (II) with ethylene oxide in an aqueous alkali solution and oxidizing the resulting phenylenedioxydiethanols to obtain crude phenylene. Method of obtaining an alkaline aqueous solution of a dioxydiacetic acid (Japanese Patent Publication Sho 62
JP-28940, JP-T3-Heisei 3-500653, JP-A-3-38544
JP-A-4-173764), a method of obtaining an alkali aqueous solution of crude phenylenedioxydiacetic acids by etherifying dihydroxyethoxybenzenes (II) and halogenated acetic acid with an aqueous alkali solution, and the like. Can be Among them, the latter method is preferable because the content of phenylenedioxydiacetic acids in the crude phenylenedioxydiacetic acids is high.

[0008] Representative examples of the dihydroxybenzenes (II) include resorcinol and hydroquinone.
Among them, resorcin is preferable. Examples of the halogenated acetic acid include, for example, monochloroacetic acid and monobromoacetic acid, among which monochloroacetic acid is preferable.
The amount of the halogenated acetic acid to be used is generally about 2.0 to 4.0 mol times, preferably about 2.2 to 3.0 mol times, relative to dihydroxybenzenes.

[0009] Examples of the alkali in the aqueous alkali solution used in the above etherification reaction include hydroxides and carbonates of alkali metals such as sodium and potassium. Among them, sodium hydroxide and potassium hydroxide are preferred. The amount of the alkali to be used is generally about 1.8 to 2.5 equivalents, preferably about 1.9 to 2.1 equivalents, per 1 mol of the halogenated acetic acid. The concentration of the aqueous alkali solution varies depending on the type of alkali,
For example, in the case of sodium hydroxide, about 20 to 50% by weight is used.

[0010] Specific production methods for the etherification reaction include:
For example, a method of co-injecting a halogenated acetic acid and an aqueous alkali solution into an aqueous solution of dihydroxybenzenes, a method of co-injecting and mixing a halogenated acetic acid and an aqueous alkali solution in a solution of dihydroxybenzenes dissolved in a small amount of an aqueous alkaline solution, and And a method of co-injecting an aqueous alkali solution in which the compounds are dissolved and a halogenated acetic acid. In the etherification reaction, the pH of the reaction solution is adjusted to 7.5 to 12
It is preferably carried out on the order of magnitude, preferably on the order of 7.5 to 8.5. When the pH of the reaction solution is less than 7.5,
Hydroxyphenylene acetic acids tend to increase, which is not preferable. If it exceeds 12, it is not preferable because halogenated acetic acid tends to hydrolyze.

[0011] The etherification reaction is usually carried out at about 80 ° C to 110 ° C, preferably at about 90 ° C to 100 ° C. The etherification reaction is preferably performed until the halogenated acetic acid in the reaction mass disappears, and the reaction time is usually about 1 to 10 hours.

[0012] The present invention relates to a method for producing purified phenylenedioxydiacetic acids by subjecting an aqueous alkali solution of crude phenylenedioxydiacetic acids to acid precipitation with a mineral acid and then keeping the solution warm. At least 10% by weight of the alkaline aqueous solution of
It is characterized in that the temperature is kept at 80 to 110 ° C.

When the temperature at which at least 10% by weight of the aqueous alkali solution of the crude phenylenedioxydiacetic acids using a mineral acid exceeds 50 ° C., the resulting purified phenylenedioxydiacetic acids are obtained. This is not preferable because impurities in the solution tend to increase. Although it is possible to carry out the above-mentioned temperature at less than 0 ° C., it is not economically preferable because a refrigeration facility or the like is required. The weight of acidifying out an aqueous alkali solution of crude phenylenedioxydiacetic acids at 0 to 50 ° C.
If it does not reach 10% by weight of the total aqueous alkali solution, the purity of purified phenylenedioxydiacetic acids tends to decrease, which is not preferable.

As a method for acid precipitation of an aqueous alkali solution of crude phenylenedioxydiacetic acids with a mineral acid, for example, (1) 0
A method of adding an alkaline aqueous solution of crude phenylenedioxydiacetic acids to a mineral acid at a temperature of 0 to 50 ° C, and (2) mixing an alkaline aqueous solution of a crude phenylenedioxydiacetic acid and a mineral acid at 0 to 50 ° C (3) a method of adding a mineral acid to an aqueous alkaline solution of crude phenylenedioxydiacetic acids at 0 to 50 ° C., and (4) a method of adding at least 10% by weight of crude phenylene dioxydiacetic acid to a mineral acid at 0 to 50 ° C. A method of adding an alkaline aqueous solution of a dioxydiacetic acid and adding the remaining alkaline aqueous solution at about 50 to 110 ° C., (5) an alkaline aqueous solution of at least 10% by weight of a crude phenylenedioxy diacetic acid at 0 to 50 ° C. And mineral acid are co-injected and mixed.
A method of co-mixing at about 0 to 110 ° C, (6) 0 to 50
A method of adding a mineral acid to an aqueous alkali solution of at least 10% by weight of a crude phenylenedioxydiacetic acid at 50 ° C., and mixing the remaining aqueous alkali solution and the mineral acid at about 50 to 110 ° C .;
And the like. Among them, any one of the methods (1), (2), (4) and (5) is preferable, and particularly the method (1)
Alternatively, the method (4) is preferable, and the method (4) is more preferable.

The mineral acids of the present invention include, for example, mineral acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. Particularly, sulfuric acid and hydrochloric acid are preferable, and hydrochloric acid is particularly preferable. The mineral acid is preferably used as an aqueous solution, and its concentration is usually 5 to 2
It is about 0% by weight. The amount of the mineral acid to be used is usually 1 mole of phenylenedioxydiacetic acids (I),
It is about 2.6 to 3.4 equivalents.

After the alkaline aqueous solution of the crude phenylenedioxydiacetic acids and the mineral acids are all precipitated out, the resulting mixture is
温 110 ° C., preferably about 85-95 ° C.
If the heat retention temperature is lower than 80 ° C, impurities in the resulting purified phenylenedioxydiacetic acids tend to increase. Therefore, if the temperature is higher than 110 ° C, the mixture will boil and This is not preferable because crystals tend to adhere to the surface. The warming time is usually about 0.1 to 4 hours, preferably about 0.5 to 2 hours.

After keeping the temperature, the above mixture is cooled to about 50 to 0 ° C, preferably about 40 to 10 ° C. Next, the obtained crystals are separated by a method such as filtration, washed with water and dried if necessary, whereby the desired purified phenylenedioxydiacetic acids can be obtained. Further, the obtained purified phenylenedioxydiacetic acids can be purified by recrystallization or the like, if necessary.

[0018]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) (Production example of crude aqueous solution of phenylenedioxydiacetic acids) In a nitrogen atmosphere, 297.3 g of resorcinol (2.
70 mol) and 225.0 g of water were added and stirred to dissolve the crystals. Then add 48% caustic soda water to bring the solution pH to 7.8.
After heating to 95 ° C, the monochloroacetic acid 6
An aqueous solution consisting of 63.4 g (7.02 mol) and 389.6 g of water was added over 5 hours, and the mixture was further stirred at the same temperature for 2 hours. A 48% aqueous sodium hydroxide solution was added dropwise so that the pH of the aqueous solution was 7.5 to 8.1 during heating, dropping, and keeping the temperature. The total amount of the used 48% aqueous sodium hydroxide solution was 1110 g (4.93 equivalents). The amount of the obtained alkaline aqueous solution of the crude phenylenedioxydiacetic acids was 2685 g, which was a slurry. A part of the slurry was dissolved in a 50% aqueous acetonitrile solution, and analyzed by an area percentage method using high performance liquid chromatography. The results are shown in Table 1.

(Production Example of Purified Phenylenedioxydiacetic Acids) In a nitrogen atmosphere and under stirring, 247.9 g of a 15% hydrochloric acid aqueous solution was placed in a flask.
(1.02 mol) and cooled to 15 ° C. Next, 297.0 g of the above-mentioned alkaline aqueous solution of crude phenylenedioxydiacetic acids (equivalent to 0.30 mol as resorcinol) was gradually added to this aqueous solution, and then an aqueous alkali aqueous solution preparation tank of crude phenylenedioxydiacetic acids was added with 33 g of water. Washed wash water was added. These additions took one hour. During this time, the mixture in the flask was maintained at 15 ± 1 ° C. Next, the resulting mixture was heated to 90 ° C., kept at the same temperature for 1.0 hour,
Cooled to ° C. After filtering the precipitated crystals, water
After washing with 100 g and vacuum drying at 60 ° C., 61.8 g of pure white phenylenedioxydiacetic acids were obtained. Part of this
After dissolving in 50% acetonitrile aqueous solution, analysis was performed by an internal standard method using high performance liquid chromatography. The results are shown in Table 1. The abbreviations are II-1: 3-phenylenedioxydiacetic acid, III-1: 1,3-hydroxyphenoxyacetic acid, III-2: 2-carboxymethyl-1,3, respectively.
-Phenylenedioxydiacetic acid and 4-carboxymethyl-
Represents a mixture of 1,3-phenylenedioxydiacetic acids.

Example 2 A flask was placed in a nitrogen atmosphere under stirring.
273.45 g (0.90 mol) of a 15% hydrochloric acid aqueous solution was charged and cooled to 20 ° C. Next, 130.0 g of an aqueous alkaline solution of the crude phenylenedioxydiacetic acids obtained in the same manner as in Example 1.
(Corresponding to 0.13 mol of resorcinol, 43% by weight of an aqueous alkali solution of crude phenylenedioxydiacetic acids) was added. At this time, the reaction temperature was 50 ° C. Subsequently, 172.54 g of an aqueous alkali solution of crude phenylenedioxydiacetic acids (corresponding to 0.17 mol as resorcinol, 57% by weight of the aqueous alkali solution of crude phenylenedioxydiacetic acids) was added, and then 33 g of water was added to the crude phenylenedioxydiacetic acid. Washing water for washing the acetic acid alkaline aqueous solution adjusting tank was added. The reaction temperature when all the alkaline aqueous solutions of the crude phenylenedioxydiacetic acids were mixed with the aqueous mineral acid solution was 90 ° C. These additions took one hour. Then, the resulting mixture is 90 ° C
For 1.0 hour, and then cooled to 30 ° C. After filtering the precipitated crystals, the crystals were washed with 100 g of water and vacuum-dried at 60 ° C. to obtain 63.0 g of white crystals. The analysis results of the obtained crystals are shown in Table 1.

(Examples 3 to 7, Comparative Examples 1 to 3) Hereinafter, the procedures were carried out in accordance with Examples 1 and 2 except for the conditions shown in Table 1, and the results are shown in Table 1. Here, the start temperature of the acid precipitation conditions refers to the temperature of the aqueous hydrochloric acid solution before mixing of the aqueous hydrochloric acid solution and the alkaline aqueous solution of the crude phenylenedioxydiacetic acids, and the end temperature under the same conditions is Indicates the temperature of the mixture when all the aqueous alkali solutions of diacetic acids are mixed with the aqueous hydrochloric acid solution. The amount of addition refers to the total weight of crude phenylenedioxydiacetic acids in an aqueous alkali solution of 100%.
Represents the weight ratio of the aqueous alkali solution mixed at 0 to 50 ° C., and the term “time” represents the time required for mixing the aqueous hydrochloric acid solution and the total amount of the aqueous alkaline phenylenedioxydiacetic acid solution. In addition, the heat retention temperature refers to the temperature of the mixture obtained by keeping the mixture of the aqueous hydrochloric acid solution and the total amount of the crude phenylenedioxydiacetic acids in the alkaline aqueous solution for 1 hour.

[0023]

【table 1】

[0024]

According to the present invention, purified phenylenedioxydiacetic acids can be produced with high purity and high yield.

Claims (5)

[Claims] [Claim 1] The following general formula (I) (Wherein R represents a halogen, a carboxy group or a hydrocarbon group having 4 or less carbon atoms, and n represents an integer of 0 to 3). In a method for producing purified phenylenedioxydiacetic acids by subjecting an alkaline aqueous solution of oxydiacetic acids to acid precipitation with a mineral acid and keeping the temperature, at least 10% by weight of the aqueous alkali solution of crude phenylenedioxydiacetic acids is reduced to 0%. Acid precipitation at ~ 50 ° C, keeping the temperature at 80 ~ 110 ° C
A process for producing purified phenylenedioxydiacetic acids. 2. An alkaline aqueous solution of crude phenylenedioxydiacetic acids is represented by the following general formula (II): (Wherein, R and n represent the same meanings as described above). An alkaline aqueous solution of crude phenylenedioxydiacetic acids obtained by reacting a dihydroxybenzene represented by the formula (I) with a halogenated acetic acid in an aqueous alkaline solution. A process for producing purified phenylenedioxydiacetic acids. 3. The method according to claim 2, wherein the dihydroxybenzenes are resorcinol and / or hydroquinone. 4. The method according to claim 2, wherein the halogenated acetic acid is monochloroacetic acid. 5. The method according to claim 1, wherein the mineral acid is hydrochloric acid and / or sulfuric acid.