JPH11180934A - Production of para-nitrobenzoic acid and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing p-nitrobenzoic acid by which the selectivity and conversion to the p-nitrobenzoic acid are extremely improved, and further to provide an apparatus therefor. SOLUTION: This method for producing p-nitrobenzoic acid by heating a polystyrene with nitric acid in the presence of manganese dioxide is regulated so that the specific gravity of the nitric acid after finishing the reaction may be 1.25-1.5. Concretely, the reaction is carried out by refluxing the first reaction vessel 1 charged with nitric acid with 1.42 specific gravity and the manganese dioxide, and the second reaction vessel 2 charged with the nitric acid with 1.42 specific gravity, sending nitric acid solution containing the manganese dioxide in a vessel 3 for both supplying the nitric acid and recovering the nitric acid to the vessel 1, and simultaneously flowing out the nitric acid solution in the vessel 1 to the vessel 2, inserting granular polystyrene into the vessel 1, and carrying out the reaction while flowing out the content of the vessel 1 to the vessel 2 through a communication pipe 6. The water, nitrogen dioxide and nitrogen oxide generated in the vessels 1 and 2 are recovered as the nitric acid with 1.37 specific gravity in the vessel 3 after converting the nitrogen oxide into the nitrogen dioxide by introducing air from a line 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for producing paranitrobenzoic acid using a styrene-based polymer as a raw material.

[0002]

2. Description of the Related Art Conventionally, a method for producing paranitrobenzoic acid using a styrene-based polymer as a raw material has been described, for example, in the 26th Autumn Meeting of the Chubu Chemical Association, Chapters (Japanese) August 2, 7
On the 5th issue), the synthesis of paranitrobenzoic acid using polystyrene as a raw material is reported, but the selectivity and the conversion of paranitrobenzoic acid are not satisfactory.

An object of the present invention is to provide a method and an apparatus for producing paranitrobenzoic acid in which the selectivity and the conversion of paranitrobenzoic acid are significantly improved.

[0004]

According to the first aspect of the present invention, there is provided a method for producing paranitrobenzoic acid, comprising heating a styrenic polymer together with nitric acid in the presence of a metal atom-containing compound. A first reaction vessel is charged with a predetermined amount of nitric acid having a certain specific gravity and a certain amount of a metal atom-containing compound, and a second reaction vessel is charged with a certain amount of nitric acid having a certain specific gravity. A step of charging a certain amount of nitric acid having a certain specific gravity and a certain amount of a metal atom-containing compound into a recovery container, heating the first reaction container and the second reaction container and raising the temperature until a predetermined reaction temperature is reached; Meanwhile, nitric acid containing a metal atom-containing compound is dropped and supplied from a nitric acid supply container and a nitric acid recovery container to a first reaction container through a dropping port by a dropping pump, and at the same time, the first reaction container and the second reaction container are connected. Ream Discharging the contents exceeding a predetermined amount in the first reaction vessel through the pipe to the second reaction vessel to adjust the liquid volumes of the nitric acid supply / nitric acid recovery vessel and the second reaction vessel to predetermined amounts, respectively, A certain amount of a styrene polymer is charged into a reaction vessel, and nitric acid containing a metal atom-containing compound is dropped and supplied from a dropping port to a first reaction vessel by a dropping pump from a nitric acid supply vessel and a nitric acid recovery vessel. While allowing the contents of one reaction vessel to flow out to the second reaction vessel, the reaction is carried out at a predetermined reaction temperature for a certain period of time.
A step of recovering volatile components generated in the reaction vessel as nitric acid having a specific gravity of a predetermined value or more in a nitric acid supply vessel and a nitric acid recovery vessel, and a step of filtering and separating products of the first and second reaction vessels to collect Wherein the specific gravity of nitric acid in the system at the end of the reaction is not less than a predetermined value.

[0005] In the second aspect of the present invention, after the reaction and nitric acid recovery step in the method of the first aspect of the present invention, the product in only the second reaction vessel is recovered by filtration / separation, and nitric acid is supplied. A step of taking out and recovering nitric acid from the container and nitric acid recovery vessel, charging a certain amount of filtrate from the second reaction vessel and a fixed amount of nitric acid into a nitric acid supply container and a nitric acid recovery vessel, and removing a certain amount of nitric acid at a certain specific gravity In the second reaction vessel, heating the first reaction vessel and the second reaction vessel and raising the temperature until the reaction temperature reaches a predetermined reaction temperature. The nitric acid contained is dropped from the dropping port to the first reaction vessel by a dropping pump.
Supplying the contents of the first reaction vessel to the second reaction vessel at the same time so that the liquid volumes of the nitric acid supply vessel / nitric acid recovery vessel and the second reaction vessel are respectively predetermined; The nitric acid containing the metal atom-containing compound is dropped and supplied from the nitric acid supply vessel and the nitric acid recovery vessel to the first reaction vessel by a dropping pump, and the contents of the first reaction vessel are placed in the second reaction vessel. While flowing to
Reacting at a predetermined reaction temperature for a predetermined time, recovering volatile components generated in the first reaction container and the second reaction container as nitric acid having a specific gravity of a predetermined value or more in a nitric acid supply container and a nitric acid recovery container, and a second reaction Performing various steps including a step of filtering and separating the product in the container to collect, and at the end of the various steps, the specific gravity of nitric acid in the system is equal to or more than a predetermined value;
The present invention relates to a method for producing paranitrobenzoic acid, which comprises repeating the above steps to produce paranitrobenzoic acid with good reproducibility.

In a third aspect, the present invention provides a method for producing paranitrobenzoic acid, comprising heating a styrenic polymer together with nitric acid in the presence of a metal atom-containing compound,
A first reaction vessel is charged with a specific gravity of nitric acid and a metal atom-containing compound, and a second reaction vessel is charged with a specific gravity of nitric acid,
After heating the first reaction vessel and the second reaction vessel to a predetermined reaction temperature, nitric acid and a styrene-based polymer having a constant specific gravity are continuously supplied to the first reaction vessel, and the contents in the first reaction vessel are The reaction is carried out while flowing to the second reaction vessel, the product is filtered and separated from the obtained reaction solution, the filtrate is circulated to the first reaction vessel, and the specific gravity of nitric acid in the filtrate is not less than a predetermined value, The present invention relates to a method for producing paranitrobenzoic acid, comprising recovering volatile components generated from a first reaction vessel and a second reaction vessel as nitric acid having a specific gravity of a predetermined value or more, and continuously producing paranitrobenzoic acid.

According to a fourth aspect of the present invention, in the fourth aspect, a first reaction vessel provided with a heating means and a dropping port, a second reaction vessel provided with a heating means, a nitric acid supply / nitric acid recovery vessel, a first reaction vessel and a second reaction vessel are provided. A communication pipe connecting the two reaction vessels to allow the contents in the first reaction vessel to exceed a predetermined amount to flow out to the second reaction vessel;
Nitric acid containing a metal atom-containing compound is dropped from the nitric acid supply container and the nitric acid recovery container to the first reaction container by a dropping pump.
The present invention relates to an apparatus used in the method according to the first or second aspect, comprising a nitric acid supply means for supplying and a nitric acid recovery means for recovering volatile components generated in the first reaction vessel and the second reaction vessel as nitric acid having a predetermined specific gravity.

[0008] The present invention provides, in the fifth aspect, a first reaction vessel provided with a raw material supply means, a heating means and a dropping means,
A second reaction vessel provided with a heating means, a communication pipe connecting the first reaction vessel and the second reaction vessel to allow a content exceeding a predetermined amount in the first reaction vessel to flow out to the second reaction vessel, Means for filtering and separating the product from the reaction solution at the outlet of the vessel, means for circulating the filtrate to the first reaction vessel, and means for recovering volatile components generated in the first and second reaction vessels as nitric acid having a specific gravity. And an apparatus used in the method according to the third aspect.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a styrene-based polymer is defined as the following repeating unit derived from styrene.

[0010]

Embedded image

Means a polymer containing

In the present invention, among the polymers containing the above-mentioned repeating units derived from styrene, a polymer (polystyrene) comprising only repeating units derived from styrene and a repeating unit derived from styrene and other ethylenic units are included. Polymers containing a repeating unit derived from a monomer having an unsaturated bond, for example, butadiene, isoprene, acrylonitrile, acrylic acid, acrylate, and the like are included.

In the present invention, the styrene polymer may have any molecular weight. In the present invention, the styrene-based polymer may be solid or liquid.

The styrenic polymer used in the present invention may be a discarded styrenic polymer product or a non-waste product.

In the present invention, the metal atom of the metal atom-containing compound is defined as IA, IIA, IIIA, IV in the periodic table of the elements.
Group A, VA and VIA metals, IB, IIB, IIIB, IV
Group B, VB, VIB and VIIB metals and Group VIII metal atoms.

In the present invention, the compound containing a metal atom is 1
It can contain one or more metal atoms.

In the present invention, the metal atom-containing compound includes, for example, metal oxides, hydroxides, fluorides, chlorides, bromides, carbonates, bicarbonates, sulfates, bisulfates, sulfites, bisulfites. , Phosphate, hydrogen phosphate, biphosphate, hydrogen phosphite, carboxylate, chlorate, ammonium salt, amine salt.

In the present invention, one kind of metal atom-containing compound may be used, or two or more kinds of metal atom-containing compounds may be used.

As specific examples of the metal atom-containing compound,
Manganese dioxide, chromium oxide, iron oxide, cobalt oxide,
Nickel oxide, vanadium pentoxide, magnesium oxide,
Calcium oxide, copper oxide, zinc oxide, antimony oxide,
Cerium oxide, tin oxide, vanadium oxide, iridium oxide, osmium oxide, copper hydroxide, chromium hydroxide, manganese hydroxide, iron hydroxide, nickel hydroxide, calcium fluoride, copper chloride, iron chloride, cobalt chloride, manganese chloride ,
Copper bromide, cobalt bromide, manganese carbonate, cobalt carbonate,
Examples include magnesium carbonate, cobalt bicarbonate, copper sulfate, cobalt sulfate, magnesium sulfate, nickel acetate, cobalt acetate, cerium acetate, lead acetate, palladium acetate, ammonium metavanadate, ammonium molybdate, and ammonium tungstate.

The nitric acid used in the present invention is 1.3
It has a specific gravity of 0 to 1.50, preferably 1.35 to 1.50, particularly preferably 1.40 to 1.50, and fuming sulfuric acid can also be used.

The nitric acid used in the present invention has a specific gravity of nitric acid at the end of the reaction in the first and second embodiments and a specific gravity of nitric acid in the filtrate in the third embodiment of 1.
It is necessary to select and use the specific gravity so as to be 25 to less than 1.50, preferably 1.30 to less than 1.50, and more preferably 1.35 to less than 1.50. If the specific gravity of nitric acid in the system at the end of the reaction is less than 1.25, the rate of change and selectivity of paranitrobenzoic acid are undesirably reduced.

In the method of the present invention, the ratio of nitric acid to the styrene-based polymer is usually 1 to 100, preferably 5 to 100, in terms of a molar ratio to the repeating unit derived from styrene.
From 70 to 70, particularly preferably from 20 to 40. If the molar ratio is less than 1, the rate of change is low, which is not preferable. If it exceeds 100, the decomposition of the reaction product is promoted, which is not preferable.

In the method of the present invention, the amount of the metal atom-containing compound used is 0.0
It is in the range of 1-1, preferably 0.05-0.25.
If the weight ratio is less than 0.01, the progress of the reaction becomes slow, and if it exceeds 1, the decomposition of the product is promoted, which is not preferred.

In the present invention, if necessary, a filter may be provided in the communication pipe to prevent the solid content of the contents of the first reaction vessel from flowing out to the second reaction vessel.

The reaction in the first reaction vessel and the second reaction vessel of the present invention is advantageously carried out under normal pressure at 110 ° C. to reflux temperature, preferably at reflux temperature. In the first and second embodiments, the control of the amount of the nitric acid containing the metal atom-containing compound from the nitric acid supply vessel and the nitric acid recovery vessel to the first reaction vessel by using a dropping pump is controlled by, for example, piezo. It can be carried out automatically using a pump (trade name, manufactured by Mutual Pharmaceutical Co., Ltd.). In addition, the above reaction temperature is controlled by an automated reaction apparatus ARS-20.
01 (manufactured by Mutual Pharmaceutical Co., Ltd.) can be automatically controlled. The control of the supply amount of nitric acid in the third embodiment can be similarly performed.

The reaction time in the method of the present invention is 12 to 1
00 hours, preferably in the range of 24-48 hours. 1
If the reaction time is less than 2 hours, the amount of the reaction intermediate is large, and the rate of change of paranitrobenzoic acid is decreased, which is not preferable.

In the first and second embodiments of the present invention,
Water and nitrogen dioxide, which are volatile components generated during the reaction in the first reaction vessel and the second reaction vessel, are cooled through a cooling pipe, and the nitrogen monoxide is volatile. After being oxidized by an oxidizing gas such as air introduced into the component line to form nitrogen dioxide, it is cooled through a cooling pipe and is recovered as nitric acid having a specific gravity in a nitric acid supply container and a nitric acid recovery container, respectively.

In the first embodiment of the present invention, after completion of the reaction, the reaction solution is withdrawn from the first and second reaction vessels, cooled, and the precipitated crystals are separated by filtration to collect the product.

In the second embodiment of the present invention, in the final cycle in which the above-mentioned steps are repeated, the products in the first and second reaction vessels are filtered after the above-mentioned reaction and nitric acid recovery step.・ Separate and collect. At this time, the first
The product obtained from the reaction vessel has accumulated from the first time.

In the third embodiment of the present invention, nitric acid and a compound containing a metal atom are charged into a first reaction vessel, nitric acid is charged into a second reaction vessel, and heated to a reaction temperature.
The styrene-based polymer and nitric acid are reacted while continuously supplying the reaction vessel, and the reaction solution at the outlet of the second reaction vessel is filtered and separated to obtain a product, and the filtrate is circulated to the first reaction vessel to carry out the first reaction. By recovering the volatile components generated in the vessel and the second reaction vessel as nitric acid having a specific gravity by the method described above, it is possible to continuously produce paranitrobenzoic acid. At this time, the specific gravity of nitric acid in the filtrate needs to be not less than a predetermined value as described above. If necessary, the second reaction vessel may be omitted.

One example of the method and apparatus of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram for explaining the first, second and fourth aspects of the present invention.
A first reaction container 1 is charged with nitric acid and a compound containing a metal atom, a second reaction container 2 is charged with nitric acid, and a nitric acid supply container and a nitric acid recovery container 3 are charged with a compound containing nitric acid and a metal atom.

The first reaction vessel 1 is heated by a heater 4 and the second reaction vessel 2 is heated by a heater 5 to raise the temperature until a predetermined reaction temperature is reached. Nitric acid containing an atom-containing compound is dropped and supplied to the first reaction vessel 1 through the dropping port 7 by the dropping pump 6 and is simultaneously connected to the first reaction vessel 1 and the second reaction vessel 2. The contents exceeding a predetermined amount in the first reaction vessel 1 are discharged to the second reaction vessel 2 through the connecting pipe 9 having It is a predetermined amount.

A styrene-based polymer is charged into the first reaction vessel 1 and a dropping pump 6
The nitric acid containing the metal atom-containing compound is dropped and supplied to the first reaction vessel 1 through the dropping port 7, and the reaction is performed while the contents of the first reaction vessel 1 flow out to the second reaction vessel 2. Water, nitrogen dioxide and nitrogen monoxide, which are volatile components generated in the first reaction vessel 1 and the second reaction vessel 2, are oxidized by the oxidizing gas from the line 10 into nitrogen dioxide, and then the first cooling is performed. Cooled by tube 11,
The nitric acid having a specific gravity equal to or higher than a predetermined value is recovered in the nitric acid supply container and the nitric acid recovery container 3. At this time, the amount of dripping is obtained by using the data detected by the temperature sensor 12 in the automated reaction device 13.
The dripping pump 6 is operated according to the output corresponding to the set value as the reaction temperature, and is automatically controlled.
Similarly, the outputs of the heaters 4 and 5 are automatically controlled.

After the completion of the reaction, the product is filtered and separated from the reaction solution in the first and second reaction vessels 1 and 2 and collected.

The exhaust gas such as the introduced oxidizing gas is discharged to the line 15 through the second cooling pipe 14.

FIG. 2 is a schematic view for explaining the third and fifth embodiments of the present invention. In FIG. 2, nitric acid and a compound containing a metal atom are charged in a first reaction vessel 1 and a second reaction is performed. After nitric acid is charged into the vessel 2 and the first reaction vessel 1 and the second reaction vessel 2 are heated to a predetermined reaction temperature, the styrene polymer and the nitric acid are continuously supplied to the first reaction vessel 1. The reaction is carried out while allowing the contents in the first reaction vessel 1 to flow out to the second reaction vessel 2, and the product is filtered and separated from the obtained reaction solution by using a filter / separator 16, and the filtrate is circulated. Circulating to the first reaction vessel 1 through the line 17, the volatile components generated in the first reaction vessel 1 and the second reaction vessel 2 are cooled by the cooler 18 while introducing oxidizing gas from the line 10 and recovered as nitric acid I do. The supply amount of the nitric acid and the reaction temperature can be performed in the same manner as in the first, second and fourth embodiments.

FIG. 3 is a schematic view for explaining a conventional method and apparatus. In FIG. 3, a styrene-based polymer, nitric acid and a compound containing a metal atom are charged into a reaction vessel 21 and a predetermined reaction temperature is applied. Perform the reaction. At this time, the reaction temperature is automatically controlled by inputting data detected by the temperature sensor 22 to the automatic reaction device 23 and controlling the output of the heater 24 so as to match the set value as the reaction temperature. An oxidizing gas is introduced from a line 25 to convert nitrogen monoxide generated in the reaction vessel 21 into nitrogen dioxide.
Water and nitrogen dioxide contained in the oxidizing gas are cooled by the third cooling pipe 26 and recovered as nitric acid, and exhaust gas is discharged from the line 27.

[0038]

The present invention will be described below in more detail with reference to Examples and Comparative Examples.

Example 1 First to fourth experiments were performed using the apparatus shown in FIG. 1 as follows.

First 500 ml glass-made first reaction vessel 1 was charged with 300 ml of nitric acid having a specific gravity of 1.42 and manganese dioxide 2.14 g, and placed in a 500 ml glass-made second reaction vessel 2 with a specific gravity of 1.42.
200 ml of nitric acid is charged, and 400 ml of nitric acid having a specific gravity of 1.42 is placed in a 1000 ml glass nitric acid supply container and nitric acid recovery container 3.
ml and 2.14 g of manganese dioxide.

While heating the first reaction vessel 1 and the second reaction vessel 2 until the reaction temperature reaches a reflux temperature of 120 ° C., 100 ml of the nitric acid solution in the nitric acid supply vessel and the nitric acid recovery vessel 3 is dropped. At the same time, 100 ml of the nitric acid solution in the first reaction
1 hour after the start of heating, the liquid volume of each of the first reaction container 1, the second reaction container 2, and the nitric acid supply / nitric acid recovery container 3 was set to 300 ml.

Next, 42.85 g of granular polystyrene was charged into the first reaction vessel 1, and the amount of the nitric acid solution dropped into the first reaction vessel 1 and the reaction temperature of 120 ° C. were measured using a piezo pump (manufactured by Mutual Pharmaceutical Co., Ltd.). Pump, trade name) and an automated reaction apparatus ARS-2001 (automated reaction apparatus, trade name, manufactured by Mutual Pharmaceutical Co., Ltd.).
The content of the first reaction vessel 1 exceeding 00 ml overflows from the communication pipe 6 and is allowed to react for 32 hours while flowing out to the second reaction vessel 2, and is generated in the first reaction vessel 1 and the second reaction vessel 2 during the reaction. The water, nitrogen dioxide and nitrogen monoxide are introduced into the line 10 to convert the nitrogen monoxide into nitrogen dioxide, and then cooled through the first cooling pipe 11, and then cooled to the nitric acid supply vessel 3 and the nitric acid recovery vessel 3. Collected as 1.37 nitric acid. The specific gravity of the recovered nitric acid was substantially equal to the specific gravity of nitric acid in the system at the end of the reaction.

After completion of the reaction, the reaction solution in the second reaction vessel 2 was taken out, cooled, and the precipitated crystals were separated by filtration. The crystals separated by filtration were subjected to hot water extraction to separate a product mainly composed of paranitrobenzoic acid. The product was analyzed by high performance liquid chromatography (HPLC). Air was introduced as an oxidizing gas at a rate of 100 ml / min, and the temperatures of the first cooling pipe 11 and the second cooling pipe 14 were set to -15 ° C or lower.

Second time In the first time, the nitric acid collected in the nitric acid supply container / nitric acid recovery container 3 was extracted and separately collected, and instead, 300 ml of the first filtrate and 100% fuming nitric acid having a specific gravity of 1.50 were used instead.
The second reaction vessel 2 was charged with 200 ml of fuming nitric acid having a specific gravity of 1.50. Next, the same operation as the first time was repeated.

The third and fourth operations were repeated for the second operation. Table 1 shows the obtained results.

Comparative Example 1 An experiment was conducted as follows using the apparatus shown in FIG. 300 ml of nitric acid having a specific gravity of 1.42 was charged into a 500 ml glass reaction vessel 21 and 1.43 g of manganese dioxide was added.
Charged. After heating the reaction vessel 21 to 120 ° C., 14.28 g of polystyrene was charged, and the reaction was carried out for 32 hours while automatically controlling the reaction temperature to 120 ° C. using the same automated reaction apparatus as in Example 1. During the reaction, air is introduced from the line 25 at a rate of 100 ml / min, and nitrogen monoxide generated during the reaction is converted into nitrogen dioxide, which is cooled together with separately volatilized water and nitrogen dioxide in the third cooling pipe 26 at -15 ° C or lower. Then, it was collected in the reaction vessel 21 as nitric acid. After the completion of the reaction, the reaction solution in the reaction vessel 21 was drawn out, cooled, and the precipitated crystals were separated by filtration, and the filtered crystals were extracted with hot water to obtain the desired product. The analysis of the target substance was performed using high performance liquid chromatography (HPLC). Table 1 shows the obtained results.

[0047]

[Table 1]

[0048] In Table 1, (* 1) is the value obtained by considering the yield of the product accumulated in the first reaction vessel 1 four times.
The average rate of change is shown, and o, m and p in (* 2) mean orthonitrobenzoic acid, metanitrobenzoic acid and paranitrobenzoic acid, respectively.

[0049]

According to the present invention, paranitrobenzoic acid can be obtained with high selectivity and high change rate, with good reproducibility, or continuously.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating first, second and fourth aspects of the present invention.

FIG. 2 is a schematic diagram illustrating third and fifth aspects of the present invention.

FIG. 3 is a schematic diagram illustrating a conventional method and apparatus.

[Description of Signs] 1 First reaction vessel 2 Second reaction vessel 3 Nitric acid supply vessel and nitric acid recovery vessel 4, 5, 24 Heater 6 Dropping pump 7 Dropping port 8 Filter 9 Communication pipe 10, 25 Oxidizing gas introduction line 11, 14 , 26 Cooling pipe 12,22 Temperature sensor 13,23 Automated reactor 15,27 Exhaust line 16 Filtration / separator 17 Circulation line 18 Cooler 21 Reaction vessel

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kenichi Oikawa 2-6-1 Otemachi, Chiyoda-ku, Tokyo Nihon Building Mutual Pharmaceutical Co., Ltd. (72) Inventor Nobuo Suwabe 2-chome Otemachi, Chiyoda-ku, Tokyo No. 6-2 Japan Building Mutual Pharmaceutical Co., Ltd. (72) Inventor Yuji Miyazaki 2-5-2 Otemachi, Chiyoda-ku, Tokyo Japan Building Mutual Pharmaceutical Co., Ltd.

Claims (5)

[Claims] 1. A method for producing paranitrobenzoic acid, comprising heating a styrenic polymer together with nitric acid in the presence of a metal atom-containing compound, wherein a predetermined amount of nitric acid having a specific gravity and A certain amount of a metal atom-containing compound is charged, a certain amount of nitric acid having a certain specific gravity is charged into a second reaction vessel, and a certain amount of nitric acid having a certain specific gravity is added to a nitric acid supply container and a nitric acid recovery container. Loading the first and second reaction vessels until the reaction temperature reaches a predetermined reaction temperature while heating the first and second reaction vessels to reach a predetermined reaction temperature. Is dropped and supplied to the first reaction vessel through a dropping port by a dropping pump, and simultaneously, the first reaction vessel and the second
The contents exceeding a predetermined amount in the first reaction vessel are allowed to flow out to the second reaction vessel through a communication pipe connecting the reaction vessel to the second reaction vessel. In the step of quantitative determination, a certain amount of a styrene-based polymer is charged into a first reaction vessel, and a metal atom-containing compound is contained in the first reaction vessel from a nitric acid supply vessel and a nitric acid recovery vessel through a dropping port by a dropping pump. While dropping and supplying nitric acid and allowing the contents of the first reaction vessel to flow out to the second reaction vessel, the reaction is carried out at a predetermined reaction temperature for a certain period of time to remove volatile components generated in the first and second reaction vessels. A step of recovering nitric acid having a specific gravity of a predetermined value or more in a supply vessel and a nitric acid recovery vessel, and a step of filtering and separating products of the first reaction vessel and the second reaction vessel and recovering the same. of Para nitro method for producing a benzoic acid, wherein the specific gravity of the acid is equal to or greater than a predetermined value. 2. The method according to claim 1, wherein, after the reaction and nitric acid recovery step, the product in only the second reaction vessel is filtered and separated and recovered, and the nitric acid in the nitric acid supply vessel and the nitric acid recovery vessel is taken out. Charging a fixed amount of the filtrate from the second reaction vessel and a certain amount of nitric acid into a nitric acid supply container and a nitric acid recovery container, and charging a certain amount of nitric acid having a certain specific gravity into the second reaction container While heating the first reaction vessel and the second reaction vessel and raising the temperature until reaching a predetermined reaction temperature, nitric acid containing a metal atom-containing compound was dropped from the nitric acid supply capacity and nitric acid recovery vessel by a dropping pump. From the first reaction vessel to the first reaction vessel while simultaneously supplying the contents of the first reaction vessel to the second reaction vessel.
A process of flowing out to the reaction vessel and setting the liquid volumes of the nitric acid supply vessel / nitric acid recovery vessel and the second reaction vessel to predetermined amounts, respectively, putting a certain amount of the styrene-based polymer into the first reaction vessel and recovering the nitric acid supply vessel / nitric acid The nitric acid containing the metal atom-containing compound is dropped and supplied from the vessel to the first reaction vessel by a dropping pump, and the reaction is performed at a predetermined reaction temperature for a predetermined time while the contents of the first reaction vessel are allowed to flow out to the second reaction vessel. Recovering volatile components generated in the first reaction vessel and the second reaction vessel as nitric acid having a specific gravity of a predetermined value or more in a nitric acid supply vessel and a nitric acid recovery vessel, and filtering and separating the product in the second reaction vessel To perform various processes including the process of collecting
A method for producing paranitrobenzoic acid, wherein the specific gravity of nitric acid in the system at the end of the various steps is not less than a predetermined value, and the various steps are further repeated to produce paranitrobenzoic acid with good reproducibility. 3. A method for producing paranitrobenzoic acid, comprising heating a styrene-based polymer together with nitric acid in the presence of a compound containing a metal atom, wherein a first reaction vessel is provided with a compound having a specific gravity of nitric acid and a metal atom-containing compound. Then, a specific gravity of nitric acid is charged into the second reaction vessel, and the first reaction vessel and the second reaction vessel are heated to a predetermined reaction temperature. The polymer is continuously supplied, the reaction is carried out while the contents in the first reaction vessel are allowed to flow to the second reaction vessel, the product is filtered and separated from the obtained reaction solution, and the filtrate is transferred to the first reaction vessel. Circulating, the specific gravity of nitric acid in the filtrate is not less than a predetermined value,
A method for producing paranitrobenzoic acid, comprising recovering volatile components generated from a reaction vessel as nitric acid having a specific gravity of a predetermined value or more and continuously producing paranitrobenzoic acid. 4. A first reaction vessel provided with a heating means and a dropping port, a second reaction vessel provided with a heating means, a nitric acid supply vessel and a nitric acid recovery vessel, and a connection between the first reaction vessel and the second reaction vessel. Nitric acid containing a metal atom-containing compound is dropped into the first reaction vessel by a dropping pump from a communication pipe through which a content exceeding a predetermined amount in the first reaction vessel flows out to the second reaction vessel, a nitric acid supply vessel and a nitric acid recovery vessel. 3. An apparatus used in the method according to claim 1, comprising nitric acid supply means for supplying and nitric acid recovery means for recovering volatile components generated in the first reaction vessel and the second reaction vessel as nitric acid having a predetermined specific gravity. 5. A first reaction vessel provided with a raw material supply means, a heating means and a dropping means, a second reaction vessel provided with a heating means, and a first reaction vessel connecting the first reaction vessel and the second reaction vessel. , A means for filtering / separating the product from the reaction solution at the outlet of the second reaction vessel, a means for circulating the filtrate to the first reaction vessel, and a means for circulating the filtrate to the first reaction vessel. The apparatus used in the method according to claim 3, comprising means for recovering volatile components generated in the reaction vessel and the second reaction vessel as nitric acid having a predetermined specific gravity.