JP2006062994A - Production method for high quality diaminodiphenyl ether - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a diaminodiphenyl ether in a high yield with stable high quality via a stepwise producing process which uses an aminophnol and a chloronitrobenzene as starting materials and comprising an etherification process, a hydrogen addition process and a distillation purifying process, by quickly and accurately measuring a solution composition in each reaction process and reflecting the results of measurement to the automatic control of the process. <P>SOLUTION: The diaminodiphenyl ether with stable high quality is produced in high yield by installing near infrared absorption spectroscopic arrangements and directly measuring compositions of the solution in etherification, hydrogen addition and distillation purification processes which allow the accurate measurement of the reaction condition and purification condition and continuous downloading of the results to a distributed process control system for automatic calculation and control. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing diaminodiphenyl ether obtained through each step of an etherification reaction step, a hydrogenation reaction step, and a distillation purification step, and more specifically, a near-infrared absorption spectrum spectroscopic analyzer for directly analyzing the solution composition of each step. Measures reaction conditions and distillation conditions automatically by continuously taking measurements using the and incorporating the measurement results into a distributed process control system. In particular, the present invention relates to a method for producing high-quality diaminodiphenyl ether, in which the reaction is completed and the product is dispensed.

  Diaminodiphenyl ethers are useful compounds as raw materials for producing high-performance aramid synthetic fibers. As a method for producing these compounds, first, halonitrobenzenes and aminophenols are subjected to heat condensation using an appropriate solvent in the presence of a catalyst to obtain aminophenylnitrophenyl ethers as intermediate products. Then, a method for obtaining diaminodiphenyl ethers by carrying out a hydrogenation reaction on the obtained aminophenylnitrophenyl ethers in the presence of a catalyst is known and established as a commercial technique. For example, in a liquid medium containing N, N-dimethylformamide, aminophenylnitrophenyl ethers are produced in the presence of a noble metal catalyst in the reaction medium by producing an aminophenylnitrophenyl ether in the presence of a noble metal catalyst. Has been disclosed (see, for example, Patent Document 1).

  However, the etherification reaction step, the hydrogenation reaction step, and the distillation purification step for obtaining diaminodiphenyl ethers are generally carried out industrially in batch or semi-batch methods. In the reaction process of hydrogenation, even if it is blended at a constant raw material charge ratio and further reacted under the same temperature and pressure conditions, due to disturbances such as fluctuations in the raw material composition and side reactions, the reaction end time is reached for each batch Since a difference arises, if only the reaction time is used as a measure of the end point, the yield is reduced due to insufficient reaction.

  Similarly, in the distillation purification process, after removing the solvent used in the reaction under reduced pressure, low-boiling impurities such as aminophenol and aniline are appropriately removed as the first fraction, and the diaminodiphenyl ether product is discharged. Although it is necessary to be batch-type or semi-batch-type, even if the same decompression conditions, temperature conditions, and the amount of the low-boiling initial fraction are withdrawn, it may vary due to fluctuations in the distillation raw material composition obtained by the reaction. As a result, a certain quality cannot be maintained.

  In order to avoid these problems, there is a method of confirming the completion of the reaction and the quality of the distilled product by performing composition analysis using gas chromatography or the like every batch, but not only the manual loss increases but also takes about 1 hour. Decrease in production capacity due to analysis results waiting time, progress of side reactions due to missed reaction end point in reaction process, insufficient extraction of low boiling point initial fraction in distillation purification process, etc. However, there has been a problem that the product quality represented by the purity of the product and the visible light transmittance is often deteriorated.

Therefore, in order to produce diaminodiphenyl ether having a stable and high quality in a high yield, a rapid measurement method is adopted, and a stable quality control and production process for producing a product having a constant quality at all times is adopted. A method of performing control has been desired.
Japanese Patent Laid-Open No. 48-22433

  The object of the present invention is to solve the problems of the prior art described above, in the production process of diaminodiphenyl ether obtained through each step of the etherification reaction step, hydrogenation reaction step, distillation purification step, the solution composition of each step. By measuring the results quickly and accurately and reflecting the obtained measurement results in the process control system, the reaction conditions and distillation conditions are automatically controlled, and the reaction is completed and the products are kept under appropriate conditions that always provide a constant quality. Is to provide a method for producing high-quality diaminodiphenyl ether.

  In order to achieve the above-mentioned object, the inventors have rapidly used a process solution in each of the etherification reaction step, hydrogenation reaction step, and distillation purification step to obtain diaminodiphenyl ether using aminophenol and chloronitrobenzene as raw materials. The composition was measured, and further investigations were made on how to reflect the results in the automatic process control.

  As a result, it was found that reaction conditions and purification conditions can be measured quickly and accurately by directly measuring the solution composition of each step using a near infrared absorption spectrum spectrometer. Finding that diaminodiphenyl ether with high purity quality can be stably produced in high yield by reducing the manual work loss by continuously taking the measurement results into the distributed process control system and performing automatic calculation and control. The present invention has been completed.

That is, the object of the present invention is to
In the process of producing diaminodiphenyl ether by sequentially passing each step of etherification reaction step, hydrogenation reaction step, distillation purification step using aminophenol and chloronitrobenzene as raw materials,
(A) In the etherification reaction step, the concentrations of aminophenol, chloronitrobenzene as raw materials, and aminophenylnitrophenyl ether as an intermediate product in the reaction solution are continuously measured using a near infrared absorption spectrum spectrometer. The etherification reaction conversion rate is calculated by continuously taking the obtained results into a distributed process control system and automatically calculating them, and the reaction conversion rate is 98% while controlling the reaction temperature and reaction time. At this point, the reaction is automatically stopped and paid out to the next process.
(B) In the hydrogenation reaction step, the concentration of the intermediate product, aminophenylnitrophenyl ether, and the product, diaminodiphenyl ether, in the reaction solution is continuously measured using a near-infrared absorption spectrum spectrometer. The results obtained are continuously taken into a distributed process control system and automatically calculated to calculate the hydrogenation reaction conversion rate, while controlling the reaction temperature, reaction pressure, reaction time, and hydrogen supply rate while controlling the reaction conversion rate. Automatically stops the reaction when it reaches 99% or more, and pays out to the next process.
(C) In the distillation purification step, the concentration of impurities other than diaminodiphenyl ether in the distilled distillate, and simultaneously the visible light transmittance of 400 to 700 nm of the distillate are continuously measured using a near infrared absorption spectrum spectrometer. Measured, and the results obtained are continuously incorporated into a distributed process control system. (1) Impurity concentration other than diaminodiphenyl ether is 5 wt% or less, and (2) Visible light transmittance at 400 to 700 nm is 60%. After the initial boiling component of diaminodiphenyl ether is separated and removed from the diaminodiphenyl ether until the above is obtained, the product, high-purity diaminodiphenyl ether is distilled off and the product is automatically discharged by changing the flow path, and the diaminodiphenyl ether is further removed. Automatically stops product withdrawal at any stage prior to the distillation of the higher boiling heavy matter. Characterized in that it can be achieved by the method for producing a high-quality diaminodiphenyl ether.

  According to the production method of the present invention, the reaction solution composition and product composition of the diaminodiphenyl ether production process can be measured quickly and accurately, and the obtained measurement results are continuously taken into the distributed process control system. Thus, since various controls relating to reaction conditions and distillation conditions can be performed automatically, it is possible to always obtain diaminodiphenyl ether having a certain high quality in a high yield.

Hereinafter, the present invention will be described in detail.
Specific examples of the aminophenol used as a raw material in the present invention include o-, m-, and p-aminophenol, and specific examples of chloronitrobenzene include o- and p-chloronitrobenzene. Aminophenyl nitrophenyl ether obtained by subjecting these to etherification condensation reaction is aminophenyl nitrophenyl ether corresponding to the combination of the above raw materials.

  In addition, any near-infrared spectroscopic analyzer used in the present invention can be adopted as long as it is an on-line compatible model. In the present invention, the visible light transmittance of a diaminodiphenyl ether product is one of the items to be measured. Therefore, it is preferable to use a model having a measurement wavelength range of 400 to 2500 nm. In addition, since the measurement points are divided into three processes, for example, a multi-measurement point compatible model is preferable so that even one spectroscopic analyzer can be used. By setting in this way, the concentration of a predetermined substance in the reaction solution can be continuously measured, and the obtained result can be continuously taken into the distributed process control system and automatically calculated to calculate the reaction conversion rate. . Furthermore, from the result, the reaction is automatically stopped when the reaction conversion rate becomes a predetermined value or more while controlling the reaction temperature, pressure, time, etc., and the next process can be dispensed. Furthermore, as a cell to be a measurement point in the spectroscopic analyzer, either a flow cell type or an insertion type can be adopted as long as it is a transmission type.

  The site to which the measurement point cell is attached may be directly attached to the container or pipe in which the liquid to be measured exists by a known method, but in particular, the etherification reaction step for obtaining diaminodiphenyl ether and the measurement solution for the hydrogenation reaction step Among them, there are 0.2 to 10% by weight of particulate catalysts such as alkali metal salts and noble metals, which may cause errors in the measurement of the near-infrared spectrum analyzer due to the influence of light scattering. . Therefore, it is preferable to measure the liquid after removing the catalyst particles as much as possible, and install a known solid-liquid separation device in the reactor circulation piping or the like to set the measurement point on the solution piping after separating the catalyst particles. If provided, stable measurement can be performed. In addition, in the distillation purification process that is not affected by disturbance due to particles or the like, it is preferable in terms of maintenance to install the product distillate in the delivery pipe of the liquid feed pump.

  The measurement method using a near-infrared spectroscopic analyzer in the process for obtaining diaminodiphenyl ether will be sequentially described below. (1) The substance to be measured in the etherification reaction step is raw material aminophenol, chloronitrobenzene and aminophenylnitrophenyl ether obtained by a condensation reaction. Since these substances give characteristic spectra in the near infrared wavelength range of 1400 to 2200 nm when measured in N, N-dimethylformamide solvent, the near infrared absorption spectra of the process reaction solutions having various reaction rates are different. At the same time, chemical analysis of the reaction solution is carried out, and a calibration curve corresponding to the concentration of each substance can be obtained by correlating the numerical processing data of the near infrared absorption spectrum with the chemical analysis value.

  Next, (2) the substance to be measured in the hydrogenation reaction step is an intermediate product aminophenylnitrophenyl ether obtained by the etherification reaction and diaminodiphenyl ether as a product. These substances show characteristic spectra in the near infrared wavelength range of 1400 to 2200 nm when measured in N, N-dimethylformamide solvent, and among them, nitro compounds are obtained by hydrogenation at around 1500 nm and 2000 nm. In particular, a change in the near-infrared absorption spectrum can be found as the group changes to an amino group. Therefore, similar to the etherification reaction, near infrared absorption spectra of process reaction solutions having various reaction rates are measured, and at the same time, chemical analysis of the reaction solution is performed, and numerical processing data and chemical analysis values of the near infrared absorption spectrum are compared. If correlation is taken, a calibration curve corresponding to the concentration of each substance can be obtained.

  Next, (3) the substance to be measured in the distillation purification step is the impurity concentration other than the product diaminodiphenyl ether and the visible light transmittance of 400 to 700 nm of the product distillate. Diaminodiphenyl ether has a characteristic spectrum in the near-infrared wavelength range of 1400 to 2200 nm. Among them, impurities having a lower boiling point other than diaminodiphenyl ether, which is a major factor that lowers purity, are in the region of 1400 to 1500 nm. In particular, the near-infrared absorption spectrum is changed, and impurities having a higher boiling point can be found in the vicinity of 1500 nm and in the spectral region of 1900 to 2200 nm. Therefore, the near-infrared absorption spectra of process solutions with various levels of purification can be measured, and at the same time, chemical analysis of the solutions can be performed, and the correlation between the numerical processing data of the near-infrared absorption spectra and the chemical analysis values can be obtained. A calibration curve corresponding to the concentration of can be obtained. Here, impurities having a lower boiling point than diaminodiphenyl ether are specifically aminophenol and aniline, and impurities having a higher boiling point (heavy component) than diaminodiphenyl ether are specifically N-phenylformamide, and N, N-diphenylformamide.

  On the other hand, for the visible light transmittance of 400 to 700 nm, if the near-infrared absorption spectrum spectrometer is a type having a spectral capability, the absorption spectrum in the visible light region can be used as it is, and the chemical analysis value If the correlation is obtained after correcting the difference using a simple coefficient, a calibration curve corresponding to the visible light transmittance can be obtained. Further, as a method of reducing the measurement error from the chemical analysis value, a part of the absorption spectrum in the near infrared region in addition to the visible light region can be added as a spectrum analysis correction term.

  As in the above (1) to (3), the near-infrared absorption spectrum spectroscopic analyzer having the obtained calibration curve is subjected to an etherification reaction step, a hydrogenation reaction step, and a distillation purification step for producing diaminodiphenyl ether. By installing in each step, the concentration change in the process solution and visible light transmittance can be obtained quickly, so that the progress of the reaction and the purification status of the product can be observed in real time. Then, the reaction conversion rate is calculated from the calibration curve, and the reaction temperature, pressure, time, etc. are controlled from the results, and when the reaction conversion rate exceeds a predetermined value, the reaction is automatically stopped and the next process is dispensed. It can be carried out. The reaction conversion rate is preferably 98% or more in the etherification reaction step and 99% or more in the hydrogenation reaction step. In addition, when the concentration of impurities other than diaminodiphenyl ether in the distillation purification step is 5 wt% or less, the first-boiling components having a lower boiling point than diaminodiphenyl ether can be separated and removed until the visible light transmittance at 400 to 700 nm becomes 60% or more. preferable. After that, diaminodiphenyl ether of high purity is distilled off, and diaminodiphenyl ether is automatically discharged from the distillation purification device by changing the flow path. Dispensing of diaminodiphenyl ether can be stopped.

Moreover, the measurement method using the near-infrared ray can employ either a batch method or a continuous method for obtaining diaminodiphenyl ether.
Furthermore, measurement results obtained using a near-infrared spectroscopic analyzer can be continuously loaded into a distributed process control system, enabling various process controls, and the reaction is completed and products are dispensed automatically. A system can be constructed. As a result, high quality diaminodiphenyl ether can be obtained in high yield.

  The contents of the present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto.

[Example 1]
In a process for producing 3,4′-diaminodiphenyl ether obtained by sequentially passing an etherification reaction step, a hydrogenation reaction step, and a distillation purification step using m-aminophenol and p-chloronitrobenzene as raw materials. A commercially available on-line near-infrared absorption spectrum spectrometer (measurement wavelength region: 400 to 2500 nm) corresponding to multiple measurement points was installed.

  In the etherification reaction step, a branch pipe is attached to the circulation pipe of the etherification reactor, a liquid cyclone for removing the catalyst is installed in the branch pipe, and a cell serving as a near-infrared measurement point is installed in the pipe on the solution outlet side. Inserted. The two outlets of the hydrocyclone, that is, the piping on the solution side and the catalyst particle slurry side, each have a flow returning to the reactor after passing through the measurement point.

  An etherification reactor is charged with equimolar amounts of m-aminophenol and p-chloronitrobenzene, N, N-dimethylformamide as a solvent, and 5% by weight of potassium carbonate as a catalyst, and stirred and circulated. While performing, it was heated to 150 ° C. under normal pressure.

  The concentration of the substance continuously obtained from the near infrared absorption spectrum analyzer is taken into the distributed process control system, and the progress of the reaction is displayed by continuously displaying the etherification reaction conversion rate and reaction time in a trend. Monitored. Furthermore, a basic pattern consisting of reaction conversion rate and reaction time indicating the degree of reaction progress is stored in the distributed process control system, and if the reaction conversion rate deviates by 2% from the basic pattern, it alerts the operator. At the same time, the process control was performed to automatically correct the reaction conversion rate and reaction time by changing the temperature to the minus side in the case of an upper deviation and to the plus side in the case of a lower deviation. When the reaction conversion rate reached 98%, an operator was notified with an end message, and at the same time, a reaction was automatically terminated and a system for paying off to the next process was constructed. The standard deviation of the reaction conversion rate obtained by the near-infrared absorption spectrum spectrometer and the reaction conversion rate obtained by the chemical analysis measurement of the process solution was 0.3%.

  Next, in the hydrogenation reaction step, a branch pipe is attached to the circulation pipe of the hydrogenation reactor, a liquid cyclone for removing the catalyst is installed in the branch pipe, and a near-infrared measurement point is provided on the solution outlet side pipe. A cell was inserted. The two outlets of the hydrocyclone, that is, the pipes on the solution side and the catalyst particle slurry side, each have a flow returning to the reactor.

  The mixed solution obtained in the etherification reaction step described above passes through the step of removing the catalyst, and then the whole amount is led to the hydrogenation reactor, and 1% by weight of palladium-carbon is added as the catalyst, followed by stirring and circulation. While supplying hydrogen, the reaction was conducted at 100 ° C. and 0.7 MPa.

  The concentration of the substance continuously obtained from the near-infrared spectrometer is incorporated into the distributed process control system, and the progress of the reaction is monitored by continuously displaying the hydrogenation reaction conversion rate and reaction time in a trend. did. Furthermore, a basic pattern consisting of reaction conversion rate and reaction time indicating the degree of reaction progress is stored in the distributed process control system, and if the reaction conversion rate deviates from the basic pattern by 2% vertically, the operator is At the same time as alarming, by changing the temperature and / or pressure to the minus side in the case of an upper deviation and changing the temperature and / or pressure to the plus side in the case of a lower deviation, the reaction conversion rate and reaction time are automatically set. Correction process control was performed.

  When the reaction conversion rate reached 99%, an operator was notified with an end message, and at the same time, the reaction was automatically terminated and a system for paying off to the next process was constructed. The standard deviation of the reaction conversion obtained by the near-infrared absorption spectrum spectrometer and the reaction conversion obtained by chemical analysis measurement of the process solution was 0.1%.

  Next, in the distillation purification step, a side flow pipe branched to the reflux pipe of the distillation tower was attached, and a cell serving as a near infrared measurement point was inserted. The side flow pipe has a flow that returns to the reflux pipe again after passing through the measurement point.

  The mixed solution obtained in the above-described hydrogenation reaction step passes through the step of removing the catalyst, and is then led to the entire hold tank. The pot of the distillation tower is charged to a pot level of 80% from the hold tank, and the solvent (N, N-dimethylformamide) was removed at 150-200 ° C. under a reduced pressure of 2 kPa.

  After removing the solvent, distillation purification was started at 250 to 270 ° C. under a reduced pressure of 2 kPa, and the concentration of all impurities in the distillate continuously obtained from the near infrared absorption spectrum spectrometer was 2% by weight or less, In addition, the first-run components were extracted until the visible light transmittance at 500 nm was 60% or more, and when the set value was reached, the operator was notified by a message, and the flow path was changed to start dispensing the product. As a result of analysis, impurities at this time were m-aminophenol and aniline as low-boiling components, and N-phenylformamide and N, N-diphenylformamide as high-boiling components (heavy components).

  In the distributed process control system, the concentration of impurities and visible light transmittance are always displayed as a trend, and distillation purification is performed while monitoring by the system, so if there is an abnormality in quality, product delivery is automatically stopped. It is possible to make it. In addition, the system continuously monitors the liquid level at the bottom of the distillation column, and when the liquid level in the distillation column pot reaches 10%, the distillation is automatically stopped and a system for discharging the heavy pot residue is constructed. did.

  The standard deviation between the measured value obtained by the near-infrared absorption spectrum spectrometer and the value obtained by the chemical analysis measurement of the process solution is 0.1 to 0.2% by weight as the impurity concentration and 3 as the visible light transmittance. %Met.

  The quality of the 3,4′-diaminodiphenyl ether finally obtained as a final product after passing through the above steps continuously always has a purity of 99.5 wt% or more and a visible light transmittance at 500 nm of 80% or more. I had it. In addition, there was no particular process delay due to waiting for the analysis results.

[Example 2]
In the etherification reaction step and the hydrogenation reaction step for obtaining 3,4′-diaminodiphenyl ether, the chemical analysis value was measured using a near-infrared absorption spectrum spectrometer without removing the catalyst particles in the solution. The standard deviation from the reaction addition rate calculated from the above was 5%. Therefore, in order to perform near infrared analysis in the etherification reaction step and hydrogenation reaction step for obtaining 3,4′-diaminodiphenyl ether, it is not essential to remove the catalyst particles present in the solution, but stable measurement accuracy. It was confirmed that better results were obtained by removing the catalyst particles in order to obtain the above. Further, as in Example 1, there was no particular process delay time due to waiting for the analysis result.

[Comparative Example 1]
In the process of obtaining 3,4'-diaminodiphenyl ether, when the completion of reaction in the etherification reaction step, the hydrogenation reaction step, and the delivery time of the product in the distillation purification step are all determined by gas chromatography, a step waiting for the analysis result There was a delay of about 3 hours per day.

  According to the production method of the present invention, the reaction solution composition and product composition of the diaminodiphenyl ether production process can be measured quickly and accurately, and the obtained measurement results are continuously taken into the distributed process control system. Thus, since various controls relating to reaction conditions and distillation conditions can be performed automatically, it is possible to always obtain diaminodiphenyl ether having a certain high quality in a high yield. Further, since the process delay time caused by waiting for the analysis result hardly occurs, the manufacturing can be efficiently performed in terms of time.

Claims (2)

In the process of producing diaminodiphenyl ether by sequentially passing each step of etherification reaction step, hydrogenation reaction step, distillation purification step using aminophenol and chloronitrobenzene as raw materials,
(A) In the etherification reaction step, the concentrations of aminophenol, chloronitrobenzene as raw materials, and aminophenylnitrophenyl ether as an intermediate product in the reaction solution are continuously measured using a near infrared absorption spectrum spectrometer. The etherification reaction conversion rate is calculated by continuously taking the obtained results into a distributed process control system and automatically calculating them, and the reaction conversion rate is 98% while controlling the reaction temperature and reaction time. At this point, the reaction is automatically stopped and paid out to the next process.
(B) In the hydrogenation reaction step, the concentration of the intermediate product, aminophenylnitrophenyl ether, and the product, diaminodiphenyl ether, in the reaction solution is continuously measured using a near-infrared absorption spectrum spectrometer. The results obtained are continuously taken into a distributed process control system and automatically calculated to calculate the hydrogenation reaction conversion rate, while controlling the reaction temperature, reaction pressure, reaction time, and hydrogen supply rate while controlling the reaction conversion rate. Automatically stops the reaction when it reaches 99% or more, and pays out to the next process.
(C) In the distillation purification step, the concentration of impurities other than diaminodiphenyl ether in the distilled distillate, and simultaneously the visible light transmittance of 400 to 700 nm of the distillate are continuously measured using a near infrared absorption spectrum spectrometer. Measured, and the results obtained are continuously incorporated into a distributed process control system. (1) Impurity concentration other than diaminodiphenyl ether is 5 wt% or less, and (2) Visible light transmittance at 400 to 700 nm is 60%. After the initial boiling component of diaminodiphenyl ether is separated and removed from the diaminodiphenyl ether until the above is obtained, the product, high-purity diaminodiphenyl ether is distilled off and the product is automatically discharged by changing the flow path, and the diaminodiphenyl ether is further removed. Automatically stops product withdrawal at any stage prior to the distillation of the higher boiling heavy matter. Characterized that, the method of producing a high-quality diaminodiphenyl ether to.   The production method according to claim 1, wherein the impurities other than diaminodiphenyl ether are aminophenol and aniline as low-boiling components, and N-phenylformamide and N, N-diphenylformamide as high-boiling heavy components.