JPH02255639A - Production of 4,4'-(1,6-hexamethylenedioxy)-bis-benzoic acid - Google Patents

Abstract

PURPOSE:To easily obtain the title compound by reaction of a potassium salt of p-hydroxybenzoic acid with 1,6-dihalogenated hexamethylene in a solvent prepared by mixing water and dimethylsulfoxide at a specified ratio and by separation of the resulting product through filtration followed by neutalization with an acid. CONSTITUTION:A potassium salt of p-hydroxybenzoic acid of formula I is reacted with a 1,6-dihalogenated hexamethylene of formula II (X is Cl or Br) in a water-dimethylsulfoxide mixed solvent with the weight ratio of DMSO to H2O <=1.4 (pref. 0.1-1.0) at 50-200 deg.C under such a condition that the weight ratio of the mixed solvent to the sum of the compounds of formulas I and II fall between 3 and 11 (pref. 4 and 8). After the reaction, the objective compound, a potassium salt is filtered and separated and then neutralized to effect final separation.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to the production of 4.4°-(1,6-hexamethylenedioxy)-bis-benzoic acid, which is useful as a raw material for polymers such as polyester and polyamide. Regarding the method.

[Prior Art] Regarding the production method of 4.4'-(1,6-hexamethylenedioxy)-bis-benzoic acid, for example, Jour
nal of Organic Chemistry
26+ 474+ (1961) with P-hydroxybenzaldehyde and 1. 4 by reacting with 6-dibutetramohexamethylene in ethanol in the presence of metallic sodium.
．． 4″-(1,6-hexamethylenedioxy)-bis-
After obtaining benzaldehyde, 4°4°-( A method is known in which ethyl 1,6-hexamethylenedioxy)-bis-benzoate is obtained and then hydrolyzed.

[Problem to be solved by the invention] However, since the former method uses expensive silver nitrate, it is not possible to obtain 4.4"-(1,6-hexamethylenedioxy)-bis-benzoic acid at low cost. .

The latter production method uses ethyl P-hydroxybenzoate as a raw material and reacts it with 1,6-dibromohexamethylene to produce 4,4'-(1,6-hexamethylenedioxy).
- A method for hydrolyzing bis-ethyl benzoate,
Because ethyl P-hydroxybenzoate, which is more expensive than P-hydroxybenzoic acid, is used as a raw material and the manufacturing process is complicated, these manufacturing methods are economically inexpensive.
It cannot be said that this is a method for producing -(1,6-hexamethylenedioxy)-bis-benzoic acid.

The present inventors have previously applied for a patent (Japanese Patent Application No. 63-11354).
8), as a production method for obtaining 4.4' = (1,6-hexamethylenedioxy)-bis-benzoic acid,
P- represented by the following formula (III) (where M represents an alkali metal)
An alkali metal salt of hydroxybenzoic acid and 1,6-dihalogenated hexamethylene represented by the following formula (I[[) % formula %) (where X represents CI or Br) are mixed from water and alcohol. A method for conducting the reaction in a mixed solvent was disclosed.

However, the above patent application (Japanese Patent Application No. 113548/1983)
When the alkali metal salt of the reaction product 4,4''-(1,6-hexamethylenedioxy)-bis-benzoic acid is neutralized and precipitated with acid, free 4.4'-(l,6 -hexamethylenedioxy)-bis-benzoic acid is obtained, but when the target product is filtered, the target product is present as fine particles in the slurry solution, so the filtration operation requires 4.4'
It has not been easy to separate and purify -(1,6-hexamethylenedioxy)-bis-benzoic acid.

[! Means for solving la] The present inventors have developed a 4.4'
-(1,6-hexamethylenedioxy)-bis-benzoic acid, as a result of intensive study on the production method, we found that the potassium salt of P-hydroxybenzoic acid represented by the following formula (1) and the following formula (II) X-( CHx) h-X (If) 1
, 6-dihalogenated hexamethylene is reacted in a solvent mixed with water and dimethyl sulfoxide in a specific ratio, and after the reaction is completed, 4.4'-(1,6-hexamethylenedioxy)-bis-benzoin is reacted with 6-dihalogenated hexamethylene. The present invention was achieved by discovering that filtration performance is improved when filtering and separating a potassium salt of an acid, and when filtering after neutralization and precipitation with an acid.

That is, the present invention relates to the potassium salt of P-hydroxybenzoic acid represented by the following formula (1) and the following formula (n) 1,6-dihalogenated hexamethylene represented by formula (1) and ( The reaction is carried out in a solvent in which the weight ratio of the mixed solvent to the added weight of the compound shown in If) is in the range of 3 to 10, and after the reaction is completed, the reaction product 4,4'-(1,6-hexamethylene Production of 414゛-(1,6-hexamethylenedioxy)-bis-benzoic acid, which is characterized by filtering and separating the potassium salt of dioxy)-bis-benzoic acid, and further neutralizing and precipitating it with an acid. This invention relates to a method.

In the present invention, the potassium salt of 4,4'-(1,6-hexamethylenedioxy)-bis-benzoic acid has a higher solubility than its sodium salt at the reaction temperature in a mixed solvent of dimethyl sulfoxide and water. The solubility difference due to temperature was large, and the crystal grain size became relatively large after cooling, so the filterability of the solution was improved.

The most preferred solvent for use in the present invention is a mixed solvent of dimethyl sulfoxide and water, and when a mixed solvent of methanol and water is used, 4゜4'-(1,6-hexamethylenedioxy)-bisbenzoic acid Both sodium and potassium acid salts have poor filterability and require a long time to separate and purify.

Alternatively, 4,4°-(1,6-hexamethylenedioxy)bis-benzoic acid as a potassium salt is not separated by filtration, but the acid is added directly to the reaction solution at the end of the reaction to obtain 4.4′-
It is also possible to liberate (1,6-hexamethylenedioxy)-bis-benzoic acid, but in this case the filterability of the solution was poor.

The method according to the invention, i.e. the reaction product 4,4'
The potassium salt of ~(1,6-hexamethylenedioxy)-bis-benzoic acid was separated by filtration to remove impurities, and then neutralized with acid to produce 4.4°-(1,6-hexamethylenedioxy)-(1,6-hexamethylenedioxy)-bis-benzoic acid. It has been found that precipitating oxy)-bis-benzoic acid improves the filterability of the solution.

This method of improvement could not be easily anticipated and was discovered for the first time during the study of the present invention.

The present invention will be explained in detail below.

The most important factors in improving the filtration performance during separation and purification in the present invention are the use of a mixed solvent of water and dimethyl sulfoxide as the solvent and the use of potassium salt of P-hydroxybenzoic acid.

Furthermore, the ratio of the amount of solvent used to the total weight of the solvent composition ratio and the compounds represented by formulas (1) and (U) is also important.

The composition ratio of the solvent is such that the weight ratio of dimethyl sulfoxide to water is 1.4 or less, preferably in the range of 0° to 1.0.

When the weight ratio of dimethyl sulfoxide to water exceeds 1.4, the viscosity of the solution increases and the filterability decreases, becoming no different from the filterability in the case of water and methanol solvent. or,
If the weight ratio of dimethyl sulfoxide to water is 0.1 or less, there will be no problem in filterability, but the yield and reaction rate will be reduced.

The weight ratio of the solvent to the combined weight of the compounds represented by formulas (1) and (II) is in the range of 3 to 10, preferably 4 to 8.

The weight ratio of the solvent to the total weight of the above compound is 3
If it is less than that, the potassium salt of 4,4'-(1,6-hexamethylenedioxy)-bis-benzoic acid formed will precipitate immediately, and the particles will remain fine and the filterability will decrease.
If it exceeds 10, there is no problem in terms of filterability, but 1.
The concentration of water relative to 6-dihalogenated hexamethylene increases, and side reactions such as hydrolysis of 1,6-dihalogenated hexamethylene increase, resulting in 4.4"-(1,6-hexamethylenedioxy). - The yield of bis-benzoic acid decreases.

The potassium salt of P-hydroxybenzoic acid represented by the following formula ('I) used in the present invention is P-
-Hydroxybenzoic acid can be prepared by reacting it with potassium compounds such as potassium hydroxide, potassium carbonate, etc. in a solvent of water and dimethyl sulfoxide.

This reaction is extremely rapid and instantaneously converts the compound of formula (I).

In the reaction system, it is also possible to substantially generate a potassium salt of P-hydroxybenzoic acid and carry out the reaction. That is, it can also be prepared by dissolving a potassium compound and P-hydroxybenzoic acid in water or dimethyl sulfoxide.

The 1,6-dihalogenated hexamethylene represented by the following formula (II) X-(CH2)6-X (1?) includes l,6
-dichlorohexamethylene and 1,6-dibromohexamethylene.

The reaction temperature of the present invention is 50 to 200°C, particularly preferably 8°C.
The temperature is 0 to 150°C. The reaction can be carried out at normal pressure or under elevated pressure. If the reaction temperature is below 50°C, the reaction will hardly proceed. If the reaction temperature is 200° C. or higher, P-hydroxybenzoic acid will decompose and phenol will be produced, leading to a decrease in the yield and filterability of the target compound.

1.6-Dihalogenated hexamethylene can be charged and reacted at the same time as the potassium salt of P-hydroxybenzoic acid, but after raising the temperature, use a metering pump etc.
It may also be fed into the reaction system over a period of minutes to several hours.

The generated potassium salt of 4,4'-(1,6-hexamethylenedioxy)-bis-benzoic acid precipitates in the system as the reaction progresses, so the reaction solution takes on a slurry state at the end of the reaction. .

After the reaction is completed, the reaction solution is cooled and filtered. In this case, the filtration performance is good, and the potassium salt of 4,4'-(16-hexamethylenedioxy)-bis-benzoic acid and various side reaction products can be easily separated. The filtrate can also be used again as a solvent for the reaction.

By neutralizing the resulting reaction solution with acetic acid, hydrochloric acid, sulfuric acid, etc. in the reactor used for the above reaction or using another reactor if necessary, 4 is converted into free dicarboxylic acid.
．． 4'-(1,6-hexamethylenedioxy)-bis-benzoic acid is obtained.

The amount of acid used for neutralization is 0 relative to the alkali equivalent of the preparation.
．． It is 5 equivalents or more. The obtained 4,4''-(1,6-hexamethylenedioxy)-bis-benzoic acid has good filterability and can be thoroughly washed with water or a suitable organic solvent to remove impurities.

[Function and Effect] The present invention facilitates separation and purification when producing 4,4'-(1,6-hexamethylenedioxy)-bis-benzoic acid, which is useful as a raw material for polymers such as polyester and polyamide. , the desired product can be produced economically.

[Example] Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these.

In addition, the purity of the product obtained by purification after the completion of the reaction is 4.
After methylating 4' = (1,6-hexamethylenedioxy)-bis-benzoic acid with trimethylsilyldiazomethane, it was measured by gas chromatography.

In all filtration operations, a Nutsche filter with a filtration area of 77 cm was used, and the filter paper was funnel filter paper manufactured by Kiriyama Seisakusho Co., Ltd. 9
The test was carried out using 5 mmφ and 1 μm No5C1 retained particles.

Example 1 Inside 511j equipped with a stirrer, reflux condenser, and dropping funnel
? In a 4-day flask, 55.4 g of P-hydroxybenzoic acid (0,40
1 mol), potassium hydroxide (purity 86%) 53.0g
(0.802 mol) and 29.7 g (0.192 mol) of 1,6-dichlorohexamethylene were added and stirred.
When stirred, heat was generated, and P-hydroxybenzoic acid instantly converted to the potassium salt shown by formula CI), and the reaction solution became transparent. Thereafter, the mixture was reacted under reflux at a temperature of 116° C. for 7 hours.

After the reaction is completed, cool to room temperature with ice water, 4.

The slurry-like reaction liquid in which the potassium salt of 4'-(1,6-hexamethylenedioxy)-bisbenzoic acid was precipitated was filtered under reduced pressure. The time required for filtration was 30 minutes.

Next, add 360 g of acetic acid and heat for 1 hour.
- (1,6-hexamethylenedioxy)-bis-benzoic acid was liberated.

Subsequently, the slurry containing 4.4'-(L6-hexamethylenedioxy)-bis-benzoic acid was separated by filtration. The time required for filtration was 1 hour.

The resulting cake was washed with methanol and filtered. The filtration time here was 30 minutes.

It was further washed with water and filtered. The filtration time here was 10 minutes.

The resulting cake was dried to obtain 1 g of 40° of 4,4°-(1,6-hexamethylenedioxy)-bis-benzoic acid.

The yield of the reaction on 1,6-dichlorohexamethylene was 58.4%, and the purity of the product obtained was 98%.

Example 2 The same reactor as in Example 1 was used. In a flask, 55.4 g of P-hydroxybenzoic acid (0,40
1 mol), potassium hydroxide (purity 86%) 53.0g
(0,802 mol) and 29.7 g (0,192 mol) of 1,6-dichlorohexamethylene were added thereto, and the mixture was reacted with stirring and reflux at a temperature of 112°C for 7 hours.

After the reaction was completed, it was cooled to room temperature with ice water and heated to 4.4°-(1
, 6-hexamethylenedioxy)-bis-benzoic acid was precipitated, the slurry-like reaction solution was filtered under reduced pressure. The time required for filtration here was 30 minutes.

Next, 360 g of acetic acid was added and heated for 1 hour to give a 4.4°-
(1,6-hexamethylenedioxy)-bis-benzoic acid was liberated.

Subsequently, the slurry containing 4,4°-(1,6-hexamethylenedioxy)-bis-benzoic acid was separated by filtration. The filtration time in this case was 1 hour.

The resulting cake was washed with methanol and filtered. The time required for filtration was 30 minutes. It was further washed with water and filtered. The time required for filtration at this time was 10 minutes.

The cake was dried to obtain 33.9 g of 4.4'-(1,6-hexamethylenedioxy)-bis-benzoic acid.

The yield based on 1,6-dichlorohexamethylene was 49.
4%, and the purity of the obtained product was 99%.

Table 1 summarizes the amount of raw materials charged, the amount of solvent used, and the filtration time in Examples 1 and 2.

Comparative Example 1 A mixed solvent of water and methanol was used instead of the mixed solvent of water and dimethyl sulfoxide used in Example 1.

Internal volume 1 with stirrer and heater! In a stainless steel autoclave, 323 g of water, 32 g of methanol
P-hydroxybenzoic acid 55% in a mixed solvent consisting of 3g
．． 4g (0,401 mol), potassium hydroxide (purity 8
5%), 29.7 g (0,192 mol) of 1,6-dichlorohexamethylene were added, the temperature was raised to 120° C., and the reaction was continued for 7 hours. At this time, the pressure inside the reactor was approximately 3 Kg/am'' in terms of gauge pressure. After the reaction was completed, it was cooled to room temperature with ice water.
The slurry-like reaction liquid in which the potassium salt of '-(1,6-hexamethylenedioxy)-bis-benzoic acid was precipitated was filtered under reduced pressure.

The time required for filtration was 8 hours. Next, 360 g of acetic acid was added to the cake and heated for 1 hour.
-hexamethylenedioxy)-bis-benzoic acid was released a. Subsequently, the slurry containing 4.4°-(1,6-hexamethylenedioxy)-bis-benzoic acid was filtered.

The time required for filtration was 4 hours.

The resulting cake was washed with methanol and filtered. The filtration time here was 2 hours.

It was further washed with water and filtered. The time required for filtration was 1 hour.

The resulting cake was dried to obtain 33 g of 4.4'-(1,6-hexamethylenedioxy)-bis-benzoic acid.

Yield based on 1,6-dichlorohexamethylene is 47%
The purity of the obtained product was 97%.

Comparative Example 2 In Example 1, the amount of solvent used was 4.6 in terms of weight ratio to the total weight of the compounds represented by formulas (1) and (II), whereas in Comparative Example 2, this weight ratio was It was set to 1.8.

Using the same reactor as used in Example 1, 138 g of P-hydroxybenzoic acid (
1,00 mol), potassium hydroxide (purity 86%) 131
．． 9 g (2.00 mol) and 74.1 g (0.478 mol) of 1,6-dichlorohexamethylene were added and stirred.

The reaction was carried out under reflux at a temperature of 116° C. for 7 hours.

After the reaction is complete, cool to room temperature with ice water and heat to 4°4'-
The slurry-like reaction liquid in which the potassium salt of (1,6-hexamethylenedioxy)-bis-benzoic acid was precipitated was filtered under reduced pressure. The time required for filtration was 8 hours.

Next, add 607g of acetic acid to the cake and heat for 1 hour.
,4°-(1,6-hexamethylenedioxy)-bis-
Benzoic acid was liberated.

Subsequently, a slurry containing 4.4"-(1,6-hexamethylenedioxy)-bis-benzoic acid was separated by filtration. The time required for filtration was 7 hours.

The resulting cake was washed with methanol and filtered. The filtration time here was 3 hours. It was further washed with water and filtered. The time required for filtration was 1 hour.

The resulting cake was dried to obtain 125 Ig of 4,4°-(1,6-hexamethylenedioxy)-bis-benzoic acid. The yield for 1,6-dichlorohexamethylene is 73
%, and the purity obtained was 95%.

Comparative Example 3 The weight ratio of dimethyl sulfoxide to water used in Example 1 was 0.8, but in Comparative Example 3 it was 1.6.

The reaction was carried out under the same conditions as in Example 1, and after the reaction was completed, it was cooled to room temperature with ice water, and the reaction solution was filtered. The time required for filtration was 6 hours.

Next, 600 g of acetic acid was added to the resulting cake to form a slurry, and the mixture was heated for 1 hour to liberate 4.4''-(1,6-hexamethylenedioxy)-bis-benzoic acid. The slurry containing °-(1,6-hexamethylenedioxy)-bis-benzoic acid was separated by filtration. The time required for filtration was 6 hours. Next, the resulting cake was washed with methanol. , and filtered. The filtration time here was 2 hours. It was further washed with water and filtered. The time required for filtration was 1 hour.

The resulting cake was dried to obtain 107 g of 4.4'-(1,6-hexamethylenedioxy)-bis-benzoic acid. The yield for 1,6-dichlorohexamethylene is 60
%, and the purity of the product obtained was 95%.

Comparative Example 4 While potassium hydroxide was used in Example 1, sodium hydroxide was used in Comparative Example 4.

A reactor similar to Example 1 was used. in the flask,
55.4 g of P-hydroxybenzoic acid (0,
401 mol), sodium hydroxide 32.1 g (0,80
2 moles), 29.7 g of 1°6-dichlorohexamethylene
(0°192 mol) was added and stirred. The reaction was carried out under reflux at a temperature of 116° C. for 7 hours.

After the reaction is complete, cool to room temperature with ice water and heat to 4°4'-
The slurry-like reaction solution in which the sodium salt of (1,6-hexamethylenedioxy)-bis-benzoic acid was precipitated was filtered under reduced pressure. The time required for filtration was 8 hours.

Next, 360 g of acetic acid was added and heated for 1 hour to give a 4.4°-
(1,6-hexamethylenedioxy)-bis-benzoic acid was liberated. Subsequently, the slurry containing 4,4'-(1,6-hexamethylenedioxy)-bis-benzoic acid was separated by filtration. The time required for filtration was 8 hours. The resulting cake was washed with methanol and filtered.

The appropriate filtration time here was 3 hours. It was further washed with water and filtered. The time required for filtration was 1 hour.

The resulting cake was dried to obtain 41°Og of 4,4°-(1,6-hexamethylenedioxy)-bis-benzoic acid.

The yield based on 1,6-dichlorohexamethylene was 59.
6%, and the purity of the obtained product was 98%.

In Comparative Examples 1 to 4, the amount of raw materials charged and the amount of solvent used,
and filtration time etc. are summarized in Table 2.

Claims (1)

[Claims] Potassium salt of P-hydroxybenzoic acid represented by the following formula [I] ▲Mathematical formulas, chemical formulas, tables, etc.▼[I] and the following formula [II] X-(CH_2)_6-X II] (Here, X represents Cl or Br) with 1,6-dihalogenated hexamethylene,
A mixed solvent consisting of water and dimethyl sulfoxide, in which the weight ratio of dimethyl sulfoxide to water is 1.4 or less, and the weight ratio of the mixed solvent to the sum of the compounds represented by formulas [I] and [II] is in the range of 3 to 10, and after the reaction is completed, the reaction product potassium salt of 4,4'-(1,6-hexamethylenedioxy)-bis-benzoic acid is filtered and separated. A method for producing 4,4'-(1,6-hexamethylenedioxy)-bis-benzoic acid, which further comprises neutralizing and precipitating with an acid.