JPS5810376B2 - Phenylenediaminone Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing phenylenediamine by alumonia decomposition of dichlorobenzene.

In particular, the present invention relates to a method for producing phenylenediamine in a closed system.

Among phenylenediamines, 0-phenylenediamine is a compound useful as a raw material for disinfectants, an intermediate for threne dyes, and a pigment intermediate for quinoxaline, etc., and p-phenylenediamine is a compound useful as a raw material for polyamide synthetic fibers or heat-resistant resins. It is used.

By the way, many synthetic methods are known as methods for synthesizing phenylenediamine, and for example, methods using dichlorobenzene as a starting material include p-dichlorobenzene.
A method of reacting alumonia water and copper sulfate under high temperature and pressure and recovering the generated p-phenylenediamine as hydrochloride or sulfate [German Patent No. 202170 (1907)]
〕It has been known.

However, the production of phenylenediamine by directly replacing the two halogens of this type of dihalogenobenzene with ammonia requires a very long reaction time, low yield, and a sufficient amount of catalyst. However, it has disadvantages such as:

Therefore, as an industrial method for producing phenylene diamine, p
A process has been implemented in which p-nitroaniline is obtained by amination of -chlornitrobenzene and then phenylenediamine is obtained by reduction.

However, in this method, the starting material chlornide 10
Since benzene involves a nitration reaction of chlorobenzene, there is a problem in waste acid treatment, and the production cost is high due to multiple steps.

The present invention improves the above-mentioned drawbacks at once, and its purpose is to easily produce phenylenediamine by amination in one step using inexpensive dichlorobenzene and ammonia, and to produce large quantities by recycling the entire reaction solution. The object of the present invention is to provide a manufacturing method that reduces the amount of copper catalyst consumed and produces an extremely small amount of waste water, making it possible to establish a pollution-free technology using a closed system.

The method for producing phenylenediamine according to the present invention involves reacting dichlorobenzene with an aqueous ammonia solution in the presence of a catalytic amount of a copper compound under pressure and high temperature to produce phenylenediamine by decomposition of ammonia, and then reducing the pressure to produce phenylenediamine. After removing the ammonia, the phenylenediamine produced by the aromatic amine is extracted at a temperature within the solubility limit of ammonium chloride, and this extract is distilled to obtain the phenylenediamine, while the separated aqueous extraction residue is After cooling, ammonium chloride is crystallized and filtered, and the P solution absorbs the removed ammonia, which is then recycled to the next ammonia decomposition process, thereby recycling almost the entire amount of the catalyst and reaction mother liquor. This is a characteristic feature.

As is clear from the foregoing, the reaction itself is known, but the present invention involves circulating the entire amount of the reaction mother liquor in which ammonium chloride and a copper compound as a catalyst, such as a cuprous salt, are dissolved, and replenishing the raw material dichlorobenzene and replenishment. Its feature lies in the fact that ammonia is added to the process to decompose the ammonia.

That is, when actually carrying out the reaction industrially, since ammonium chloride produced in the reaction accumulates, it is necessary to cool the reaction mother liquor and precipitate and separate the produced ammonium chloride.

The temperature conditions for the crystallization and separation of ammonium chloride must be selected so that the cuprous salt will not precipitate at the same time.

Therefore, in the circulating mother liquor after crystallizing and separating ammonium chloride, not only the entire amount of the cuprous salt used is dissolved, but also the saturated amount of ammonium chloride at the crystallization temperature is still dissolved.

The present invention is based on the new finding that the use of such circulating mother liquor does not impede the ammonia decomposition reaction.

Next, the present invention will be outlined.

The present invention is applicable to any method for producing 0-phenylenediamine, m-phenylenediamine, and p-phenylenediamine as phenylenediamine.

In other words, ammonia decomposition is 2 for dichlorobenzene.
An ammonia aqueous solution having a concentration of 0 to 60% by weight, preferably 30 to 40% by weight, is used 15 to 20 times in mole, and a cuprous salt such as cuprous chloride, cuprous iodide or cuprous sulfate is used as a catalyst. .2-0.6 molar ratio preferably 0.3-0.4
The molar ratio of addition is 170 to 250°C, preferably 200 to 250°C.
It is carried out at 230°C and under pressure of 100 to 130 ky/ca.

Therefore, the circulating mother liquor, after absorbing the ammonia removed from the reactor, is further replenished with fresh ammonia in an amount that complies with the above conditions and also compensates for the small losses in the extraction and ammonium chloride crystallization steps. An amount of cuprous salt corresponding to the amount is added and then sent to the ammonia decomposition reactor.

The concentration of ammonium chloride in the circulating mother liquor is determined by the amount of ammonium chloride at the start of the reaction and the reaction based on the knowledge that a saturated dissolved amount of ammonium chloride at around room temperature, that is, a concentration of about 20%, does not affect ammonia decomposition. The extraction step is carried out such that the concentration is determined by the sum of the amount of ammonium chloride produced in the extraction step so that crystallization of ammonium chloride does not occur.

Therefore, in the extraction step, extraction is carried out under heating, for example, at 60° C., and after the extraction, the aqueous extraction residue is cooled to precipitate and separate crystals such that the concentration of ammonium chloride satisfies the above conditions.

Regarding the catalyst, as described above, the combined use of cuprous salt and metallic copper powder has advantages such as suppressing the production of by-products and preventing coloring of the reaction solution.

However, in the case of a continuous system, it is necessary that the catalyst be dissolved in the reaction solution, so it is desirable to use the copper salt alone.

After the ammonia decomposition is completed, ammonia is removed by evaporation in the reactor or by sending the reaction liquid to a reaction liquid purge tank and reducing the pressure to normal pressure or slightly pressurized state.

At this time, the temperature is adjusted so that by-produced ammonium chloride does not precipitate.

The reaction solution from which ammonia has been removed by evaporation is extracted with an aromatic amine.

As the aromatic amine, aniline, 0-chloroaniline, 0-toluidine, etc. can be used, but aniline or 0-chloroaniline is preferable because of its high solubility in phenylenediamine.

Since these anilines are by-products of the present ammonia decomposition, this point is also an advantage of the present invention.

The extraction temperature is as described above, and the solution is separated into an extraction solvent layer and an aqueous extraction residue containing the catalyst and ammonium chloride.

Since the extraction solvent layer contains phenylene diamine, unreacted dichlorobenzene, and by-produced aniline, monochloroaniline, monochlorobenzene, etc., the produced phenylene diamine is separated by distillation by an appropriate means such as vacuum distillation.

On the other hand, the aqueous extraction residue is transferred to a crystallizer and cooled to crystallize ammonium chloride.

The crystallization temperature is adjusted to a temperature at which ammonium chloride does not precipitate in the next extraction step.

The filtrate is recycled as a reaction mother liquor, and after absorbing the excess ammonia evaporated from the reactor or reaction liquid purge tank, it is replenished with fresh ammonia to the required amount for the ammonia decomposition reaction. It is supplemented with some amount of catalyst and subsequently preheated before being sent to the ammonia decomposition reactor.

As is clear from the foregoing, the advantages of the present invention can be summarized as follows.

(1) A one-step industrial production method using dichlorobenzene as a starting material instead of the conventional industrial phenylenediamine starting material using chlornitrobenzene and requiring extremely little wastewater treatment has been established.

(2) The cuprous salt of the catalyst, which is harmful and expensive, can be reused.

(3) A by-product of the ammonia decomposition reaction can be used as an extraction solvent during extraction.

(4) A complete roasting system can be adopted by circulating the reaction mother liquor.

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Example 1-A (Mother liquor circulation basic experiment) 0-dichlorobenzene 54.51 (0,371 mol) 2
450 g (7,41 mol) of 8% ammonia water and 14.6 g (0,148 mol) of cuprous chloride were charged into a 1 liter titanium clad pressure cooker at a temperature of 170-180°C and a pressure of 32-28°C.
After reacting with stirring at kg/cm2 for 20 hours, the mixture was extracted twice with 250 g of aniline.

The production of 00-phenylenediamine in the ammonia decomposition reaction was equivalent to 79% of 0-dichlorobenzene.

O-phenylenediamine transferred to the aniline layer by extraction corresponded to 92.5% of the produced amount.

Next, ammonia and raw material 0-dichlorobenzene were added to the aqueous raffinate so as to match the previous charging conditions, and an ammonia decomposition reaction was similarly carried out at the same temperature and time.

Extraction was performed with aniline in the same manner as in the first reaction, and the amount of 0-phenylenediamine produced in the second reaction was determined to be 0.
At 280 mol, the production rate reached 75%, and the same production rate of 0-phenylenediamine was achieved only by recycling the mother liquor without adding any new catalyst, and the presence of ammonium chloride did not affect the ammonia decomposition reaction. It was shown that there is no effect.

Example 1-B 109 g (0,742 mol) of O-dichlorobenzea and 189 g (11,
12 moles), 118 g of ammonium chloride, and 2 cups of cuprous chloride.
2. The mother liquor from the previous reaction containing Og (0,223 mol) was charged into a pressure cooker and heated to 220°C in about 1 hour.
React for 1 hour at ~230°C.

(Pressure: 130-93 kg/cm2) After the reaction was completed, the composition of the product extracted with 0-chloroaniline was as follows.

After distilling off the solvent and by-products of the extract, distillation is carried out under reduced pressure, b
The p4.5111-114°C portion was obtained with a distillation yield of 94%.

Example 2 1.33 kg of 0-dichlorobenzene was injected per hour into a pressure cooker from a storage tank, and at the same time, 5.75 kg of aqueous ammonia at a concentration of 40%, 0.35 kg of cuprous chloride, and 1.32 kg of ammonium chloride were added per hour. 4.72 kg of the circulating reaction mother liquor was preheated to 200° C. and then pressurized into the pressure cooker.

The reaction temperature in the pressure cooker is 220-230°C, and the pressure is 130°C.
The ammonia decomposition reaction was carried out at 9/crA to 120 and the residence time of the reaction solution was 2 hours.

After the reaction is completed, the reaction solution is cooled and heated under normal pressure or slightly increased pressure.
Excess ammonia is removed by evaporation while maintaining the final temperature at 70°C.
This was absorbed into the circulating reaction mother liquor.

The reaction solution from which ammonia had been removed by evaporation was introduced into the bottom of a continuous extractor at a rate of 7.40 kg/hour, while continuous extraction was carried out by adding 1.48 kg/hour of 0-chloroaniline as an extraction solvent.

The extraction temperature was 70℃ to prevent precipitation of ammonium chloride.
maintained.

The solvent layer of the extract contains 0.13 kg of unreacted 0-dichlorobenzene and 0.13 kg of monochlorobenzene per hour of effluent.
5 kg, aniline 0.08 kg, o-chloroaniline 1
．． 59 to 9 and O-phenylenediamine 0, 53 k
It contained g.

This solvent layer was distilled to obtain 760 mm of monochlorobenzene.
After distillation at 132°C with Hg, 60°C with 10 mmHg of o-dichlorobenzene, 72°C with 10 mmHg of aniline, and 85°C with 10 mmHg of o-chloroaniline, 5 mmHg
, and vacuum distillation at 112-113°C to obtain 0.5 kg of 0-phenylenediamine.

Note that the amount of by-produced 0-chloroaniline was equivalent to 0.11 kg.

The aqueous extraction residue contained 2.11 kg of ammonium chloride, 0.45 kg of ammonia, 0.34 kg of cuprous chloride and 0-
It contained 0.01 kg of phenylenediamine.

The aqueous extraction residue was cooled to 10° C. to precipitate 0.80 kg of ammonium chloride.

The amount of ammonium chloride dissolved in the residual liquid was 1.32 kg.

5.54 kg of P solution, or reaction mother liquor, is discharged per hour, and after being circulated and used for the absorption of ammonia, fresh ammonia and catalyst are replenished to the above-mentioned predetermined amount, and then circulated into the pressure cooker. did.

Example 3 In place of the raw material 0-dichlorobenzene in Example 2, p
- Using dichlorobenzene, charge the previous reaction mother liquor containing 15 times the mole of aqueous ammonia at a concentration of 40% to p-dichlorobenzene and 0.4 times the mole of cuprous chloride to a pressure cooker, and then charge the same to a pressure cooker. The reaction was carried out at 230° C. for 2 hours, and ammonia was removed by evaporation, followed by extraction with o-chloroaniline to obtain p-phenylenediamine at a production rate of 52% based on p-dichlorobenzene.

Claims (1)

[Claims] 1. Dichlorobenzene is reacted with an aqueous ammonia solution in the presence of a catalytic amount of a copper compound under pressure and high temperature to generate phenylene diamine by decomposition of ammonia, and after reducing the pressure and removing excess ammonia, dissolving ammonium chloride. extracting the phenylenediamine produced by aromatic amines at a temperature within limits, distilling this extract to obtain phenylenediamine, while cooling the separated aqueous extraction residue and crystallizing and filtering ammonium chloride; A method for producing phenylenediamine, which comprises absorbing the removed ammonia with the filtrate and then recycling it to the next ammonia decomposition process, thereby recycling substantially the entire amount of the catalyst and reaction mother liquor.