JPH0386850A - Production of aromatic diamine - Google Patents

Abstract

PURPOSE:To easily obtain in high yield the title compound useful for dyes, etc., by reaction between an aromatic dihalide and ammonia in water in the presence of a specified amount of aniline using a catalyst consisting mainly of a copper compound to suppress the formation of tarry heavy materials. CONSTITUTION:Reaction is made between (A) an aromatic dihalide such as p-dichlorobenzene and (B) ammonia in water using (C) a catalyst consisting mainly of a copper compound such as copper oxide in the presence of aniline at an amount satisfying the relationship at 170-250 deg.C under a pressure of 50-160 kg/cm<2>G for 2-40hr, thus obtaining the objective compound useful as a raw material for polymers, pharmaceuticals, esp. for heat-resistant aromatic polyamides with both high mechanical strength and modulus. Reduction in the average molecular weight and the melting point of tarry heavy materials produced during the reaction will facilitate the separation process for said materials, and for above-mentioned aniline in the reaction system, the light components containing aniline in the recovery system can be unitized as a raw material by recycling to the reaction system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing an aromatic diamine by reacting an aromatic dihalide and ammonia using a catalyst mainly composed of a copper compound.

[Conventional technology]

Aromatic diamines, such as 0-phenylenediamine, p-
Phenyldiamine and other compounds are useful as polymer raw materials, dyes, pharmaceutical raw materials, etc.
It is important as a raw material for aromatic polyamides with high elastic modulus and heat resistance.

There are three typical methods for producing this aromatic cyanide, such as p-phenylenethia fruit.

(2) A method for reducing p-dinitrobenzene or p-nitroaniline.

■A method for reducing p-aminoazobenzene.

■A method of reacting p-dihalogenobenzene and ammonia.

Here, in the method (2) above, it is difficult to produce raw materials, and there are restrictions in terms of raw materials.

In addition, the method (2) above has the problem that many isomers are produced during the production of the raw material, and the yield of the target substance is not increased.

In contrast to methods (1) and (2) above, method (2) is a very rational production method because raw materials are easily available and the desired product can be obtained in fewer steps.

However, the method (2) has not been commercialized yet because the reaction conditions are high temperature and high pressure, which produces tar-like heavy substances, and the problem of a decrease in yield due to this has not been satisfactorily solved.

[Problem to be solved by the invention]

The present invention has been made against the background of the above-mentioned problems of the prior art, and aims to suppress the heavy substances generated during the production of aromatic diamine by the method (2) to a low level and to produce aromatic diamine in high yield. purpose.

[Means to solve the problem]

In the present invention, when producing an aromatic diamine by reacting an aromatic dihalide and ammonia in the presence of water using a catalyst mainly composed of a copper compound, aniline is converted to the following formula (
The present invention provides a method for producing an aromatic diamine, which is characterized in that the reaction is carried out in the presence of an aromatic diamine within the range of 1).

(1) Examples of the aromatic dihalide in the present invention include dichlorobenzene, dichloroaniline, and dichloronitrobenzene, with dichlorobenzene being preferred. These aromatic dihalides can be used in combination.

In addition to the aromatic dihalide, in the reaction system, for example, an aromatic diamine intermediate such as chloroaniline may be present in an amount of about 30 parts by weight or less per 100 parts by weight of the aromatic dihalide.

Aniline preparation concentration (hereinafter referred to as "aniline concentration")
The concentration of the formula (1) is 5 to 45% by weight, preferably 10 to 40% by weight, particularly preferably 15 to 30% by weight, and if it is less than 5% by weight, heavy substances increase and aromatic diamine The yield decreases, while if it exceeds 45% by weight, the capacity of the reaction system becomes too large, which is not suitable for the purpose of the present invention.

When the aniline concentration is within the range of formula (I), the selectivity is improved by suppressing the generation of heavy substances, and the molecular weight of the generated heavy substances is slightly lowered, and the melting point is lowered. Separation of the heavy substances becomes easy.

The amount of ammonia used is preferably 2 to 25 mol, more preferably 4 to 25 mol, per gram atom of halogen that requires amination of aromatic dihalide with ammonia.
It is 20 moles.

If the amount of ammonia used is too small, the reaction rate will decrease, while if it is too large, the increase in the reaction rate will approach saturation, and the pressure of the reaction system will increase proportionally as the amount of ammonia used increases.

The amount of water used is preferably 30 to 70% by weight, more preferably 45% by weight, based on the weight sum of both ammonia and water.
~65% by weight.

If too little water is used, the reaction rate will slow down and
Since the amount of phenylene diamine dissolved in the reaction product liquid decreases, the aromatic diamine produced when the reaction product liquid is cooled tends to precipitate, which impedes workability and operability in the process. If it is too excessive, time and energy losses will be large in post-processes such as the extraction process described later.

The amount of the copper compound used as a catalyst is preferably 0.01 to 064 gram atoms, particularly preferably 0.02 to 0.2 gram atoms, as copper atoms per mole of aromatic dihalide.

Copper compounds used as catalysts include copper oxides, hydrated oxides, copper halides, and mixed hydroxides, mixed oxides, etc. of copper and alkaline earth metals such as calcium. Alternatively, a mixed halogen compound or the like can also be used.

Among these copper compounds, cuprous oxide, cupric oxide, cupric hydroxide, cupric halides, and cupric halides are particularly preferred.

In addition, when the copper compound contains an alkaline earth metal, the content thereof is preferably 10 gram atoms or less, particularly preferably 0.1 to 5 gram atoms, per 1 gram atom of copper.

The reaction between the aromatic dihalide and ammonia in the present invention is usually carried out at a temperature of 170 to 250" C1, preferably 20
0~240°C1 pressure 50~160kg/cJ
The reaction time is usually 2 to 40 hours.

Further, the reaction may be carried out batchwise or continuously.

When the reaction is carried out continuously, it is preferable to connect two or more reactors in series so that the residence time of the reaction solution in the reactor becomes the desired reaction time.

Next, an embodiment in which aromatic cyamine is synthesized by performing this reaction continuously will be exemplified.

First, aromatic dihalide, ammonia, aniline, water, and a catalyst, preferably further an aromatic diamine intermediate, are continuously supplied to a reactor at the following ratios, so that the conversion rate of aromatic dihalide is about 90 to 98%. The reaction product liquid is continuously discharged from the reactor (hereinafter referred to as "reaction process").

At this time, the aromatic dihalide is supplied to the reactor as a new raw material, and also includes the unreacted raw material that is recovered and recycled in the purification and recycling process described below.On the other hand, the aromatic diamine intermediate is It is an aromatic diamine intermediate that is recovered and recycled in the purification and recycling process.

Furthermore, since aniline is produced as a by-product during the amination reaction of aromatic dihalides with ammonia, the ratio can be gradually increased by recycling the produced aniline and supplying it to the reactor.

By allowing aniline to coexist during this amination reaction, the yield to aromatic cyanoane is further improved.

Further, the conversion rate of aromatic dihalide in the continuous reaction is preferably controlled to about 95 to 99%. If the conversion rate is less than 95%, the conversion rate is too low and the concentration of aromatic dihalide in the recycled fraction is high, resulting in uneconomical bleeding. On the other hand, when it exceeds 99%, the proportion of by-products increases.

After the reaction is completed, the reaction product liquid obtained is preferably
Cooling to 80°C1, more preferably 30 to 70'C,
Ammonia in the reaction product liquid can be removed as a gas by returning the reaction product liquid to around normal pressure as needed, but ammonia in the reaction product liquid at around normal pressure does not necessarily have to be removed.

The reaction product liquid obtained in this way is subjected to an extraction treatment using an extractant, and then the extract is distilled to remove the extractant to obtain a crude aromatic diamine (hereinafter referred to as "
(referred to as "separation process").

That is, in this separation step, after the completion of the reaction, the resulting reaction product liquid is extracted with an extractant mainly composed of tetrahydrofuran to extract the unreacted raw materials aromatic dihalides, aromatic diamine intermediates, and crude aromatic compounds containing aniline. Extract group diamines.

The extraction agent/extractant (reaction product liquid) ratio during extraction is changed as appropriate depending on the extraction agent and the type and amount of aromatic diamine, ammonia, aromatic diamine intermediate, etc. in the extraction agent.
Usually, it is 0.5 to 10 (capacity ratio).

Further, for extraction, continuous exchange liquid-liquid extraction is preferably employed from the viewpoint of efficiency, but a batch extraction method may also be employed, and the extraction temperature is generally 10 to 100°C.

In addition, a small amount of ammonium chloride, a byproduct that made up the reaction product liquid, is extracted into the extract obtained in this separation process, so if the extractant is distilled off,
This may cause blockage in the distillation column or lead to the production of aromatic diamine hydrochloride due to the decomposition of ammonium chloride, so the extract is washed with an aqueous sodium hydroxide solution with a concentration of 1 to 30% by weight, and further ammonia It is advisable to wash with water.

After washing, the extractant, water, and ammonia are distilled off in a distillation column, and crude aromatic diamine is obtained from the can. In this case, the temperature of the can part is preferably 200°C or less, more preferably 120 to 180"C. If this temperature is too high, aromatic diamine may cause condensation due to deammoniation reaction. If the temperature is too low, the extraction agent may not be distilled off sufficiently, and water may be mixed in the distillate.In addition, the top pressure of the distillation column is usually between normal pressure and 3.
The range of atmospheric pressure.

On the other hand, an alkali metal hydroxide and/or an alkaline earth metal hydroxide may be added to the raffinate after extraction to precipitate copper compounds mainly consisting of copper oxides and/or prepared hydroxides. Accordingly, the copper compound of the catalyst can be easily separated and recovered.

In this way, the crude aromatic cyanine obtained in the separation step contains the target substance, aromatic diamine, as a main component, and contains unreacted raw materials such as dichlorobenzene, aromatic cyanine intermediates such as chloraniline, etc. Contains heavy components such as by-products such as aniline and some heavy substances.

Therefore, by distilling the crude aromatic cyanide obtained in the separation process under reduced pressure and refining it by light cut and heavy cut, it is possible to remove the unreacted raw materials, aromatic diamine intermediates, and aniline contained in the crude aromatic diamine. By separating heavy components and heavy components and recycling the heavy components to the reaction process, we aim to effectively utilize unreacted raw materials and aromatic intermediates and reduce heavy components (hereinafter referred to as "purification/refinement"). (referred to as "recycling process").

Distillation conditions for light cut vary depending on the type of aromatic diamine targeted, but the column top pressure is 30 to 300.
Torr, the tower top temperature is preferably 50 to 200°C. If the tower top pressure is less than 30 Torr, aromatic cyanide may flow out from the tower top in addition to heavy components;
If it exceeds 0 Torr, heavy components will not be sufficiently distilled out.

In addition, if the top temperature is less than 50°C, the heavy components cannot be sufficiently distilled out, whereas if it exceeds 200°C, aromatic diamines are distilled out in addition to the heavy components, but aromatic sia is accumulated in the can. There is a risk that the quality of the material may deteriorate.

Next, the heavy fraction light-cut in this way is
It is recycled to the reaction process as it is without any treatment such as washing. Note that if the amount of light cut is too large and the proportion of aniline in the raw material supplied to the reaction process becomes excessive, a part of the heavy content is removed from the system.

The amount of aniline in this heavy fraction can be adjusted to 30% by weight or more, especially 6% by weight, by controlling the reaction conditions etc.
The content is preferably 0 to 95% by weight. by this,
The amount of aniline supplied to the reaction process can be adjusted by the amount of recycled heavy components.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1, Comparative Examples 1 to 2 A titanium pressure-resistant reactor with an internal volume of 2002 mm was equipped with a stirrer and divided into 5 chambers from bottom to top by a separation plate having a through hole for circulating the content liquid. p-dichlorobenzene 3.6 kg/hour, aniline 0.4 kg/hour from the bottom
12 kg/hour of 50% by weight ammonia water and 0.17 kg/hour of cupric oxide were continuously supplied as a slurry to react at 220° C., and the reaction product liquid was extracted from the top.

The reaction pressure at this time was 142 kg/ciaC, and the residence time of the reaction product liquid was 7 hours.

After the extracted reaction product liquid was depressurized and cooled to 60°C, aromatic components were extracted by continuous countercurrent liquid-liquid extraction using twice the volume of tetrahydrofuran in a packed extraction column.

Table 1 shows the analysis results of the compounds recovered by this extraction. In addition, Table 1 also shows the analysis results (Comparative Examples 1 and 2) of compounds recovered in the same manner as above after reacting with only the charged amounts of p-chlorobenzene and aniline being changed.

Table 1 *1) The PDA yield is The value obtained as follows It is.

PDA yield = [PDA in reaction product solution (mol/hour)] x 100/
(DCB+CA in raw materials (mol/hour) - DCB+CA in reaction product liquid (mol/hour)) Example 2 An autoclave with an internal volume of 1.61 mm equipped with a rotary stirrer was equipped with a three-bottom row with a backflow prevention valve. to which p-dichlorobenzene 136.0 g/hour, p-chloroaniline ta 2 g/hour, anili 713.6 g/hour, 5.
0 wt % cupric chloride aqueous solution 240 g/waiting time liquid ammonia 220 g/hour was continuously supplied.

All autoclave temperatures were controlled at 220″C.
Raw materials were supplied from the lower part of the first unit, and liquid was extracted from the lower part of the third unit using an automatic valve that could be controlled at a pressure of 140 kg/crAG.

When the reaction became stable 24 hours after the start of the reaction, the conversion rate of p-dichlorobenzene was 98.0%. Further, the amount of p-chloroaniline was 13.8 g/hour, which was almost the same as the amount of p-chloroaniline supplied.

After the reaction product was cooled to 70'C, it was poured into a blowdown tank maintained at 2 atmospheres, and subsequently
The mixture was extracted continuously at 60'C using twice the amount of tetrahydrofuran in a rotating disk countercurrent liquid-liquid extractor with 50 plates. The extract was sent as it was to the atmospheric distillation column to distill off the extractant, and the temperature of the tank was controlled to 140''C, and the tank liquid was occasionally drawn out of the system to keep it constant. teeth,
It was crude phenylenediamine and was solidified by cooling under nitrogen.

The obtained crude phenylenediamine was cooled with liquid nitrogen, crushed, and charged into a vacuum distillation vessel for simple distillation without a column. The condenser of this distiller is controlled at 140°C by air cooling, and three traps are installed in the line connecting the condenser and the vacuum pump, each at 70°C.
Cooled to C10°C5-78°C. Distillation is 50To
Distillation starts at r r, and when the temperature of the can reaches 190°C, the degree of vacuum is increased to 30 Torr, and the temperature of the can reaches 2.
Distillation was continued until the temperature reached 30°C. At this time, what remained in the can was a heavy black tar, which was fluid at temperatures above 100''C.

In addition, the distillate and the fractions collected in the traps at 70"C and 0°C were subjected to vacuum distillation again.

A 1.5m McMahon backing column was attached to this distiller, and the line connecting the condenser and vacuum pump was equipped with three traps cooled to 70°C, 10°C, and -78°C, and the reflux ratio was 3. Distillation conditions were set such that the pressure was 30 Torr and the condenser temperature was 140°C.

In this distillation, distillation of p-phenylenediamine started when the temperature at the top of the column reached 170°C.
After removing some pre-distillation, the receiver was switched to recover purified p-phenylenediamine.

In addition, the fraction collected in the trap and the pre-distillation were combined into a heavy fraction, which was analyzed. The results are shown in Table 2.

Table 2 The recovered heavy components were mixed at a rate of 31 g/waiting time and p-dichlorobenzene at a rate of 133.3 g/hour, and the original raw materials P-dichlorobenzene and P-chloroaniline were transferred to an autoclave. and supplied in place of aniline. Thereafter, when the product was analyzed after 24 hours had passed, the results were as shown in Table 3.

(Margins below) Table 3 *l) The heavy substances were calculated assuming that the average weight was a three-nuclear condensate and the molecular weight per aromatic ring was 96.67.

On the other hand, by comparing the raw materials and the reaction products, P
When the yield to DA was determined, it was 89% (approximately 10% to heavy materials).
%, approximately 1% to aniline).

PDA yield = [PDA in the reaction product solution (mol/hour) - PD in the raw material
A (mol/hour)) From the obtained amount of PDA from the used DCB, P
When the yield of DA was calculated, it similarly reached 89%.

〔Effect of the invention〕

According to the present invention, by actively allowing aniline to exist in the amination reaction system of aromatic dihalides, the production of tar-like heavy substances is suppressed, and aromatic diamines can be obtained in high yield.

In addition, the average molecular weight of tar-like heavy substances is lowered and the melting point is lowered, making the process of separating heavy substances easier.

Furthermore, as the aniline present in the reaction system, the raw material can be effectively utilized by recycling the aniline-containing heavy fraction in the recovery system to the reaction system.

Claims (1)

[Claims] (1) When producing an aromatic diamine by reacting an aromatic dihalide and ammonia in the presence of water using a catalyst mainly composed of a copper compound, aniline is reacted with the following formula (I
) A method for producing an aromatic diamine, which comprises reacting the aromatic diamine in the presence of the following. 5≦Weight of aniline x 100/weight of aniline + weight of aromatic dihalide≦45 (weight%) (I)