JPS62198644A - Production of benzophenonepolycarboxylic acid - Google Patents

Abstract

PURPOSE:To obtain the titled substance in good selectivity under mild condition, by reacting, 1,1-bis(3,4-dimethylphenyl)ethane, etc., with an aqueous solution of nitric acid in the presence of oxygen or carrying out the reaction while injecting nitric acid or aqueous solution thereof into a reactor. CONSTITUTION:A compound expressed by the formula (R1-R6 are H or 1-3C alkyl and at least one of R1-R3 and at least one of R4-R6 are alkyl; R7 is H or 1-7C alkyl) is reacted with an aqueous solution of nitric acid to afford the titled substance. In the process, at least one of operations; (A) the compound expressed by the formula is reacted with the aqueous solution of nitric acid in the presence of oxygen and (B) the reaction is carried out at 120-200 deg.C while injecting nitric acid or aqueous solution thereof into a reactor under <=50kg/cm<2> pressure. EFFECT:The amounts of consumed nitric acid and N compounds in discharged gases are small. Useful as a raw material for polyimide, polyamide, polyester, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing benzophenone polycarboxylic acid useful as a raw material for polyimide, polyamide 9 or polyester.

[Conventional technology]

Conventional method 1: As a method for producing sulfenzophenone polycarboxylic acid having carboxyl groups on both phenyl groups, di((poly)alkylphenyl)alkylidene having at least one alkyl group on each of two phenyl groups was prepared using nitric acid. A method of oxidizing with nitric acid (nitric acid oxidation method) is known.

For example, U.S. Pat. No. 4,173,573 discloses that a 3. '
It is stated that 44'-<nzophenonetetracarboxylic acid is obtained. This nitric acid oxidation method does not require a special oxidation catalyst, the separation of the product is relatively easy, and the reaction vessel can be made of relatively inexpensive materials such as stainless steel, making it an advantageous reaction. It's a method.

[Problem that the invention seeks to solve]

However, in the conventional nitric acid oxidation method, a large amount of waste gas containing nitrogen oxides is generated during one reaction, so waste gas treatment equipment is required, a large amount of nitric acid is required, and the target product cannot be obtained. There were problems such as an insufficient rate and a high unit consumption of nitric acid.

[Means for solving problems]

That is, 1 the present invention is based on the general formula (I) (In the formula, R□ to R6 are independent from each other.

Each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R1-R3 and R4-R
At least one of 6 is an alkyl group, and ``horse'' represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. ) Leave it.

(1) An operation of reacting the compound represented by the general formula [I] with an aqueous nitric acid solution in the presence of oxygen; (2) An operation of reacting the compound represented by the general formula [I] while injecting nitric acid or an aqueous nitric acid solution into a reactor. The present invention provides a method for producing nzobuenonpolycarboxylic acid, which is characterized in that it is carried out at a rate of 50 ksl/cm' or less.

In the present invention, nitric acid refers to a solution with a concentration of 100%, and nitric acid aqueous solution refers to a solution with a concentration of less than 100%.

In addition, pressure shall indicate gauge pressure.

The compound represented by the general formula (I) in the present invention (hereinafter "
"Raw material compound") is a polyalkylinyne represented by the general formula (R□ to R3 have the same meanings as above) and R, CHO (R represents the same meanings as above). It can be easily obtained by reacting aldehyde with 1, for example, in the presence of sulfuric acid (US Patent No. a00
No. 2,034, etc.).

Examples ttfo-xylene, m-xylene or p-)silene and acetaldehyde can give 1,1-bis(dimethylphenyl)ethane.

Specific examples of other raw material compounds include bis(dimethylphenyl)methane, 1. i-his(dimethylphenyl)furo/cene, Lx-"su(dimethylphenyl)butane, 1.1-?"su(dimethylphenyl)octane.

Bis(diethylphenyl)methane, lx-bis(diethylphenyl)ethane, 1,1-bis(trimethyl7enyl)ethane, 1,1-bis(methylphenyl)ethane, 1-dimethylphenyl-1-)9 Examples include methylphenylethane. Of these raw compounds.

Preferred are compounds in which R1 to R6 represent a hydrogen atom or a methyl group, and R7 represents a methyl group.

In the present invention, the benzophenone polycarboxylic acid obtained by oxidizing the raw material compound with nitric acid is an insiphenone derivative having at least one carboxyl group on each of the phenyl groups on both sides, i.e., benzophenone dicarboxylic acid, benzophenone tricarboxylic acid. , benzophenone tetracarboxylic acid, insiphenone pentacarboxylic acid, benzophenone hexacarboxylic acid, and the like.

In the present invention, the raw material compound and the nitric acid aqueous solution are reacted in a reactor, for example, an autoclave. At this time, the concentration of nitric acid in the reaction solution is preferably from 1 to 60% by weight. If the nitric acid concentration in the reaction solution is less than 5% by weight, the reaction rate will be slow and the efficiency of the device will tend to decrease.If the nitric acid concentration in the reaction solution is too high (over 60% by weight), nitration, nitrone, etc. However, the yield of benzophenone polycarboxylic acid tends to decrease because side reactions such as chemical reactions tend to occur.

The amount of nitric acid used is 3 to 30 nitric acid per mole of raw material compound.
Moles are preferred, particularly 5-15 moles. If the amount used is less than 3 moles, the oxidation reaction will not proceed sufficiently,
A large amount of nitric acid in excess of 2 molar amounts is unnecessary for one reaction, and the amount of nitric acid produced after the reaction is disadvantageous when recovering the nzophenone polycarboxylic acid.

In addition, the degree of 1 reaction source is usually 100 to 220°C, preferably 1
The temperature is 20-200°C. If the reaction temperature is less than 100°C, a yellow compound is likely to be produced as a by-product. On the other hand, at high temperatures exceeding 220° C., cleavage reactions, combustion reactions, etc. occur frequently, and the yield of the desired product, benzophenone polycarboxylic acid, decreases.

In the present invention, since the pressure inside the reactor increases due to the gas generated during one reaction, it is preferable to carry out the reaction while releasing the generated gas to the outside of the reactor.

The pressure during the reaction is 50 to 9/an'', preferably 10~
However, if the pressure during one reaction is greater than 50♂♂, side reactions such as 1-decomposition reaction will occur, and the selectivity of the target product, benzophenone polycarboxylic acid, will decrease.

In addition, since the reaction is carried out in an aqueous solution system, a pressure higher than the vapor pressure of water corresponding to one reaction pressure is required, and in the case of a reaction temperature where the vapor pressure of water exceeds 10°C, one reaction pressure is required. Of course, the lower limit is equal to or higher than the vapor pressure of water.

The present invention is characterized in that at least 1'!s of the following operations (11 and (2)) are performed when carrying out the nitric acid oxidation reaction under the above conditions.

(1) Operation of reacting a raw material compound with an aqueous nitric acid solution in the presence of oxygen: Here, oxygen is pure oxygen, air, and pure oxygen can be replaced with nitrogen, carbon oxide, carbon dioxide, nitrous oxide, nitrogen dioxide, etc. It can be diluted with

The reaction method in this operation (1) is as follows.

(1) A method of filling a reactor with a raw material compound and an aqueous nitric acid solution in advance, and then raising the temperature and causing the reaction.

(Ii) A method in which a nitric acid aqueous solution is filled in advance, the shell is heated to a predetermined temperature, and then the raw material compound is supplied through a pump or the like and reacted.

(Ill1) There are several methods, such as filling only water (in part or all) into the reactor in advance, bringing it to a predetermined reaction temperature, and then supplying the raw material compound and nitric acid or nitric acid aqueous solution simultaneously or alternately. However, in the method of (Ill), the nitric acid aqueous solution supplied may have a concentration exceeding 60%.However, the concentration and amount of nitric acid in the reactor after completion of charging must be within the above-mentioned range. This is desirable.

Further, the oxygen coexisting in one reaction system may be blown into either the gas phase or the liquid phase of the reactor.

The rate of supply of oxygen depends on the ratio of the raw material to nitric acid, the reaction temperature, etc., so it varies depending on these conditions, but it is usually 0.1 to 5 ml of pure oxygen per mol of the raw material compound per hour. -E-le, preferably at a rate of 0.2 to 1 mol per hour.

If the supply rate is too high, exceeding 5 moles per hour, the oxygen supply rate will be too high compared to the reaction rate, and the oxygen utilization rate will tend to decrease. Furthermore, if the amount of sand is less than 0.1, the oxygen supply rate becomes insufficient compared to the reaction rate, and the amount of nitric acid consumed increases.

The gases generated during the reaction are 1 the oxygen gas introduced into the reactor, as well as nitrogen compounds produced by nitric acid oxidation, and carbon oxides, carbon dioxide, etc. Nitrogen compounds produced by nitric acid oxidation include -nitrogen oxide, nitrogen dioxide, nitrous oxide, nitrogen, etc.1 The method of the present invention in which oxygen coexists in the reaction system greatly reduces the amount of nitrogen compounds, and especially -The amount of nitrogen film, nitrogen dioxide, etc. generated is greatly reduced. This greatly reduces the amount of nitric acid consumed, which is extremely advantageous for industrial production.

(2) Operation of reacting while gradually injecting nitric acid or nitric acid aqueous solution into the reactor: The reaction method for this operation (2) is (!)
A method in which only the raw material compounds are heated in advance to a predetermined reaction temperature in a reactor, and then an aqueous nitric acid solution is supplied using a pump or the like to react.

(H) A method in which a raw material compound and water are heated in advance to a predetermined reaction temperature in a reactor, and then nitric acid is supplied using a pump or the like to react.

(nl> There is a method in which only the raw material compound or a part of the raw material compound and water is heated in advance to a predetermined reaction temperature in a reactor, and then nitric acid and water are supplied simultaneously or mutually to react.

In these methods (1) to (lli), the raw material compound or the raw material compound and water are heated at 100 to 220°C, especially at 1
Preferably, it is heated to 20 to 200°C.

Further, it is preferable that the nitric acid is supplied at an average rate of 1 to 20 moles per hour per mole of the raw material compound. If it exceeds 20 moles per hour, it tends to be difficult to control the removal of reaction heat, and if it is less than 1 mole per hour, the reaction time becomes long and becomes inefficient.

In the present invention, operation (11) and operation (2) can be used together, but in that case, operation (2) is performed in the presence of oxygen, and the amount and rate of oxygen supply are (
This is described in the case of operation 1).

In the operations (1) and (2) above, 1, for example, a cooling pipe for discharging the gas generated during one reaction into the reactor, an internal pressure control device for controlling the pressure of the gas discharged from the cooling pipe, etc. Operation 1) requires a high-pressure gas injection device to inject oxygen into the reaction system, and operation (2) requires a high-pressure metering pump to inject nitric acid into the reactor.
It is desirable to attach it.

In the present invention, after the completion of the reaction, the reaction product liquid is concentrated or cooled, or by cooling after concentration, the target product, crude benzophenone polycarboxylic acid, is precipitated in the reaction product liquid. By separating this by a commonly used method such as filtration or centrifugation, a crystalline solid of crude benzophenone polycarboxylic acid is obtained.

This crystalline solid can also be purified by recrystallization using a solvent such as water.

The reaction product liquid after separating the benzophenone polycarboxylic acid is usually an aqueous solution containing unreacted nitric acid, but it can be neutralized with an alkaline substance and disposed of, or it can be recycled to the oxidation reaction system. It is also possible to reuse it.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In the example, ``chi'' is a weight fjk standard, and pressure is a gauge pressure.

Example 1 25 g (0,105 l) of 1,1-bis-(3°4-dimethylphenyl)ethane with a purity of 98% and a concentration of 30% were placed in a 500-autoclave equipped with a gas inlet pipe and a gas outlet pipe. Nitric acid aqueous solution 3009 (1,429n
LOl) was prepared. Oxygen gas is introduced through the gas introduction pipe, the reaction system is pressurized to 20 yen 4♂, and while this pressure is maintained, oxygen gas is introduced into the gas phase at θ℃, 2001 m/min in terms of 1 atm.
The temperature of the autoclave was slowly raised while stirring the autoclave while injecting the mixture under pressure at a rate of 11.1. The temperature was raised from room temperature to 120°C in about 1 hour, maintained at 120°C for about 1 hour, and then raised to 180°C in about 1 hour, and stirring was continued for about 2 hours while maintaining this temperature. During this time, the pressure inside the reaction system was 20 kg.
/cl? The atmosphere was maintained at a constant temperature, and oxygen gas continued to flow. The gas discharged during the reaction contained unreacted oxygen, nitrous oxide, nitrogen, -carbon oxide, carbon dioxide, and trace amounts of nitrogen dioxide, but -nitrogen oxide was not detected.

All the gases discharged during the reaction and the residual gases in the autoclave after the completion of the reaction were collected and analyzed by gas chromatography, and the nitrogen elements recovered as nitrogen gas and nitrogen compound gas were converted to -carbon oxide and The carbon element recovered as carbon dioxide was measured in terms of 1,1-bis-(a4-dimethylphenyl)ethane. The results are shown in Table 1.

In addition, a portion of the obtained reaction solution was removed, and nitric acid and carboxylic acid were determined by electrical conductivity titration analysis. The results are shown in Table 1.

Next, the reaction solution was distilled and concentrated to about 150 g, which was cooled to room temperature and left overnight. The precipitated crystalline solid was separated by vacuum filtration, washed with about 100 d of water, and
After drying at 5°C overnight, 29.89 of crude 43,'44'-tetracarboxylic acid was obtained. Analysis by liquid chromatography showed that the purity was 98% or higher.

Example 2 Air was used as the circulating gas instead of oxygen gas, and the injection rate was set at 1.0 per minute. A crude a was prepared in the same manner as in Example 1, except that Ol
a'44'-benzophenonetetracarboxylic acid was obtained.

In the same manner as in Example 1, the nitrogen element and carbon element in the exhaust gas, as well as the residual amount of nitric acid and carboxylic acid in the reaction solution after completion of the reaction, were determined. The results are shown in Table 1.

Further, the purity of the obtained crude aa'44'-incifenonetetracarboxylic acid (31.4L) was 98% or more.

Comparative Example 1 1.1 with a purity of 98ts in a 500d autoclave
-bis-(3,4-dimethylphenyl)ethane 25g (
300g of nitric acid aqueous solution with a concentration of 0.105% and a concentration of 30%
(1,429 mal) was charged, the gas phase was replaced with Fulvin gas at normal pressure, and the tank was sealed. The reaction solution was heated in a closed system while stirring, and the temperature was raised from room temperature to 120° C. in about 1 hour. Next, after holding at 120°C for about 1 hour.

The temperature was raised to 180°C in about 1 hour, and stirring was continued at this temperature for about 2 hours. As the reaction progresses, the pressure inside the autoclave gradually begins to rise, and at the end of the reaction, the internal pressure reaches s.
It became 51q/c-. After the reaction was completed, the autoclave was cooled and all the gases were collected and analyzed by gas chromatography, which revealed that -nitrogen oxide, nitrogen dioxide, nitrous oxide, nitrogen, -carbon oxide, carbon dioxide, and argon that had previously replaced the gas phase. confirmed.

In the same manner as in Example 1, the nitrogen element and carbon element in the exhaust gas, as well as the residual amount of nitric acid and carboxylic acid in the reaction solution after completion of the reaction, were determined. The results are shown in Table 1.

Further, the obtained crude aa'44'-benzophenonetetracarboxylic acid had a purity of 26.2K and 96.7%.

Example 3 In an autoclave with an internal volume of 500, 1,
25 g of 1-bis(3,4-dimethylphenyl)ethane (
0.105730/) and pure water 1509 were charged. After replacing the gas phase with argon gas and sealing the container, heating was started while stirring, and the temperature was raised from room temperature to 120° C. in 1 hour. Next, a nitric acid aqueous solution with a concentration of 60% was added every hour using a metering pump.
One reaction was started by feeding into the autoclave at a speed of 0 m. When the nitric acid aqueous solution was supplied at about 30%, the internal pressure of the reactor started to rise, and when the pressure reached 20%, use a pressure-holding valve to keep the internal pressure constant at 20%. The generated gas was extracted. After supplying a total of 150 g of the nitric acid aqueous solution, stop the metering pump and raise the temperature to 180°C in 1 hour while maintaining the internal pressure at 20 to 9/art. After raising the temperature, maintain it at 180°C for 2 hours. Stirring continued.

All the gas discharged during the reaction and the residual gas in the autoclave after the reaction was collected and analyzed by gas chromatography revealed that the gas contained nitrogen, -nitrogen oxide, nitrogen dioxide, nitrous oxide, and It was confirmed that carbon and carbon dioxide were included.

In the same manner as in Example 1, the nitrogen element and carbon element in the exhaust gas, as well as the residual amount of nitric acid and carboxylic acid in the reaction solution after completion of the reaction, were determined. The results are shown in Table 1.

In addition, the obtained crude a3. The purity of 31.6L of '44'-benzophenonetetracarboxylic acid was 98% or more.

Comparative Example 2 The reaction was carried out in the same manner as in Example 3, except that the reaction was carried out without discharging the gas generated by the reaction through the autoclave. After completing one reaction, the internal pressure in the autoclave was 78 kg.
It was "Aln".

In the same manner as in Example 1, the nitrogen element and carbon element in the exhaust gas, as well as the residual amount of nitric acid and carboxylic acid in the reaction solution after completion of the reaction, were determined. The results are shown in Table 1.

In addition, the obtained crude aa'44'-benzophenonte)
Lacarboxylic acid is 2B! The purity was 96.5%.

From the results in Table 1, the following facts are revealed.

(2) According to the present invention, nitrogen compounds in exhaust gas are reduced.

■ According to the present invention, carbon elements in exhaust gas are reduced.

This shows that the decomposition of the benzene ring is reduced and the selectivity for one reaction is increased.

■ According to the present invention, the amount of nitric acid consumed is reduced.

(2) According to the present invention, the yield and purity of crude benzophenotetracarboxylic acid are increased.

(2) According to the present invention, the yield of crude penzophenoneteto dicarboxylic acid obtained is higher than the total amount of carboxylic acid produced after completion of the reaction.

〔Effect of the invention〕

The present invention is characterized by the fact that the reaction can be carried out under milder conditions, particularly at lower pressure, compared to reactions in a closed system, and the selectivity of benzophenone polycarboxylic acid is high.

It has many features such as a small amount of nitric acid consumed, a small amount of nitrogen compounds in the exhaust gas, and the ability to simplify waste gas treatment.

Claims (1)

[Claims] 1) General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] (In the formula, R_1 to R_6 are mutually independent,
Each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R_1 to R_3 and R_
At least one of 4 to R_6 is an alkyl group, and R_
7 represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. ) In the method for producing benzophenone polycarboxylic acid, which comprises reacting a compound represented by the formula [I] with an aqueous nitric acid solution, (1) an operation of reacting a compound represented by the general formula [I] with an aqueous nitric acid solution in the presence of oxygen (2) ) A method for producing benzophenone polycarboxylic acid, characterized in that at least one operation of reacting while injecting nitric acid or an aqueous nitric acid solution into a reactor is carried out at a pressure of 50 kg/cm^2 or less. 2) The compound represented by the general formula [I] is 1,1-bis(
The method for producing benzophenone polycarboxylic acid according to claim 1, wherein the benzophenone polycarboxylic acid is 3,4-dimethylphenyl)ethane.