JPS615059A - Preparation of aminophenol - Google Patents

Abstract

PURPOSE:To obtain the aimed substance of high quality and reuse unreacted dihydric phenols, by effectively separating aminophenols and unreacted dihydric phenols from a mixture obtained by reacting the dihydric phenols with ammonia. CONSTITUTION:Dihydric phenols (example; resorcin and hydroquinone) is reacted with ammonia without any catalyst or in the presence of a water-soluble catalyst (example; ammonium chloride and ammonium sulfate). The resultant reaction mixture is distilled to remove a heavy fraction, and thus obtained distillate in maintaining its molten form, is contacted with an aliphatic ether (example; n-butyl ether and diisoamyl ether), having >=60 deg.C boiling point, and substantially incompatible with said aminophenols to obtain the aimed substance. USE:Useful as an intermediate for synthesis of medicines, agricultural chemicals, azo dyes, anti-oxidants, photographic developers, etc. and a raw material for polyimide or polyamide based heat resistant resins and so on.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing high-grade aminophenols from dihydric phenols. More specifically, from a reaction mixture obtained by t-reacting dihydric phenols with ammonia in the absence of a catalyst or in the presence of a water-soluble catalyst,
Efficiently separates aminophenols and unreacted dihydric phenols to obtain high-grade aminophenols,
This invention relates to a method for circulating unreacted dihydric phenols into a reaction system.

Aminophenols have traditionally been widely used as intermediates for pharmaceuticals, agricultural chemicals, azo dyes, antioxidants, and photographic agents, and more recently, they have been used as raw materials for polyimide or polyamide heat-resistant resins. It is an extremely useful compound industrially. No catalyst or
A method for producing amine phenols by reacting dihydric phenols with ammonia in the presence of a catalyst is known, but at that time, in addition to the target aminophenols, many unused substances are present in the reaction mixture. It contained reactive dihydric phenols and by-products.

In particular, without efficiently separating these components,
When used in medicines, agricultural chemicals, etc., high-quality medicines, agricultural chemicals, etc. could not be manufactured due to these impurities. Therefore,
Previously, a special purification process was required. Several methods have been proposed for separating 7-minophenols, unreacted dihydric phenols, and/or by-products from the reaction mixture to obtain purified aminophenols. For example, (1) JP-A-48-28429 describes a liquid-liquid extraction method using a water-diisopropyl ether solvent for crude aminophenols obtained by the reaction of dihydric phenols and ammonia in the absence of a medium. has been done.

(It) GB 1.228.568 describes a process in which crude p-aminophenol is contacted with liquid aliphatic, cycloaliphatic or aromatic ketones.

(1) British Patent No. 1.028.078 discloses that crude p-aminophenol obtained by catalytic hydrogenation of nitrobenzene under acidic conditions is treated with an aliphatic alcohol.
A method of washing, preferably with isopropanol, is described.

British Patent No. 1.824.787 describes a liquid-liquid extraction method of crude p-aminophenol using benzene, toluene, xylenes, acetic esters, and an aqueous solvent.

(V) GB 1,291,642 describes crude p-aminophenol in %l of carbon tetrachloride.

A liquid-liquid extraction method using 1.1-trichloroethane, 1.1-dichloroethane and a water solvent is described.

(VD In the specification of JP-A-55-69548, crude N
A method for extraction by bringing an aqueous p-aminophenol solution into contact with an aromatic amine is described.

Therefore, the present inventors conducted additional experiments on these separation and purification methods, and although each method was found to have a purification effect to some extent, the separation of aminophenols from dihydric phenols and/or by-products was still insufficient. In addition, (1) to (v
It was found that method D was also unsatisfactory in terms of yield. That is, in the method (1) above, since the solubility of aminophenols and dihydric phenols in water is high, the separation efficiency of aminophenols and dihydric phenols is low, and furthermore, the separation efficiency of aminophenols and dihydric phenols is low. This resulted in losses and poor yields, which was economically disadvantageous. Also, (11) above
~(The vD method was basically applied to p-aminophenols obtained by catalytic hydrogenation of donitrobenzene under acidic conditions, and was applied to p-aminophenols obtained by the reaction of dihydric phenols and ammonia. Because the by-products are fundamentally different, it has been difficult to separate aminophenols from unreacted dihydric phenols and/or by-products.

Therefore, as a result of various studies on separation and purification methods that do not have the above-mentioned drawbacks, the present inventors have determined that the reaction mixture obtained by reacting dihydric phenols and ammonia in the absence of a catalyst or in the presence of a water-soluble catalyst is subjected to distillation. It has been discovered that the above object can be achieved by contacting the distillate obtained by removing the mass with specific aliphatic ethers while maintaining its molten state, and circulating the aminophenols through precipitation separation,
We have arrived at the present invention. In the present invention, aminophenols, unreacted dihydric phenols, and/or byproducts can be efficiently separated from the reaction mixture, and the aminophenols obtained by the separation are of high quality, and It has the advantage that the bottoms obtained by distilling aliphatic ether can be recycled as is to the reaction system. That is, the present invention involves reacting dihydric phenols with ammonia in the absence of a catalyst or in the presence of a water-soluble catalyst, separating amine phenols and unreacted dihydric phenols from a reaction mixture that can complete the reaction, and In the method of recycling recovered dihydric phenols in the reaction, the distillate obtained by removing heavy components from the reaction mixture after completion of the reaction is heated to a boiling point of 60'C or higher while maintaining its molten state. have, and
The aminophenols are brought into contact with aliphatic ethers that are substantially incompatible with the aminophenols, the aminophenols are precipitated and separated, the 7E nophenols are recovered, the aliphatic ethers are distilled off, and the bottoms are reacted. This is a method for producing aminophenols, which is characterized by circulating the aminophenols into the system.

In the method of the present invention, specific examples of dihydric phenols used as reaction raw materials include catechol, resorcin, hydroquinone, 2-methylhydroquinone, 4-methyl-resorcin, 5-methyl-resorcin,
5-isopropylresorcin, 3-methyl-catechol.

Examples include 4-methylcatechol, 4-tert-butylresorcin, 4-tert-butylcatechol, and among these 2@5' phenols,
It is preferable to use a dihydric phenol without a substituent, and it is particularly preferable to apply the method of the present invention to resorcinol or bitrotinone. Furthermore, the ammonia used in the present invention can be used either as aqueous ammonia or as liquid ammonia. The usage rate of ammonia is
The amount is preferably in the range of 0.5 to 10 mol per mol of dihydric phenols. If it is less than 0.5 mol, the production of heavy components will increase, and if it exceeds 10 mol, it will be undesirable to produce lyaminophenols, in which the recovery burden of ammonia is significant.

In the present invention, the reaction between dihydric phenols and ammonia can be carried out without a catalyst or in the presence of a catalyst.

Examples of the catalyst include known water-soluble catalysts, such as various ammonia compounds, ammonium chloride, ammonium sulfate, and ammonium phosphate. Further, although the reaction is carried out under an ammonia atmosphere, it is also possible to carry out the reaction under an inert gas atmosphere such as argon, helium, or nitrogen.

In the present invention, after the ammonia, etc. contained therein are removed by distillation etc. from the reaction finished layer and the reaction product mixture as necessary, the heavy components contained in the reaction mixture are further removed. A distillate containing amine phenols and unreacted dihydric phenols obtained by separation by distillation or the like is brought into contact with a specific aliphatic ether I while maintaining its molten state. Unreacted dihydric phenols and/or by-products (e.g. aromatic diamines) are dissolved in aliphatic ethers, and the target amine phenols are substantially incompatible with aliphatic ethers and are separated. becomes possible. The aminophenol layer in a molten state and the unreacted dihydric phenol-containing aliphatic ether layer may be separated into liquid-liquid as they are, or if necessary, by cooling this mixed layer while stirring, The precipitated aminophenols can also be efficiently recovered by precipitating the aminophenol layer while solidifying it and performing a filtration operation or the like. The aliphatic ethers used here have a boiling point of 60°C or higher,
It is substantially incompatible with the amine phenols, and examples thereof include dichloroethyl ether, dichloroisopropyl ether, isopropyl ether, n-butyl ether, diisoamyl ether, and ethylene glycol diethyl ether. Particularly preferred are n-butyl ether and diisoamyl ether. The amount of aliphatic ether used in the present invention varies depending on the target impurity or the composition of the reaction solution, but it is sufficient to use the amount by weight of 0.5 to 10 times the amount of aminophenol.

After the aminophenols are separated from the reaction mixture by the method described above, the aliphatic ether layer is removed by distillation or the like and recycled to the distillation extraction system. In addition, the bottoms can be recirculated as is to the reaction system.

The contact between the distillate containing the amine phenols and the aliphatic ethers can be carried out under increased pressure, normal pressure, or reduced pressure depending on the melting temperature of the distillate and the boiling point of the aliphatic ether used. It is also possible.

After contacting the distillate containing the aminophenols with the aliphatic ethers, the separated and recovered aminophenols can be dried under reduced pressure to form a product depending on the purpose of use. The product is purified by distillation, etc.

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

Example-1 ■ Resorcinol 110P (1.0 mol), 28
% ammonia water 91.2 mm (1.5 mol in ammonia)
After replacing with N11, the temperature was raised to 240°C.
The amination reaction was carried out for several hours. After the reaction was completed, excess ammonia was removed by purging while cooling, and the reaction mixture was taken out. As a result of gas chromatography (hereinafter abbreviated as Go) analysis, resorcinol 44. (l and m-aminophenol 5
5.7) was included.

This reaction mixture was transferred to an 800 ccB pear-shaped flask, and first, water was distilled off under a reduced pressure of 100 IIIH9, followed by distillation to remove heavy components under 5 WIHP. GC analysis of the distilled resorcinol m-aminophenol showed that the volume was 41.89%.

Subsequently, this distillate and 200 g of n-butyl ether as a solvent were charged into a 1 liter separable flask, and Ns
The distillate was brought into contact with the distillate at 120° C. for 15 minutes while maintaining its molten state under flowing conditions, and then cooled to 80° C. to precipitate m-7 minophenol. After the precipitated crystals were separated from the P solution by filtration, n-butyl ether 2002 was further charged and melted in contact at 120° C. for 15 minutes, and the same operation as the first time was carried out to obtain crystals of m-aminophenol. The weight of the crystals dried at 60°C under reduced pressure is 45.89 m
- The purity of the aminophenol was outside 99.8.

(2) Using the entire amount of the n-butyl ether layer from which the m-aminophenol obtained in (1) was separated, the mixture was heated at 200 rtan.
The solvent was distilled off under reduced pressure of H9 to recover unreacted resorcinol. In the obtained still liquid, resorcinol was found to be 41.7
It contained 7.92 F, m-aminophenol. New resorcinol 68.89 was added to this recovered resorcin, 28% ammonia water 91.29 was added, and the result of GC analysis was resorcinol 44.5v to m-7 minophenol 6.
8.1y was included, and the first reaction could be reproduced.

Example 2 ■ The same procedure as in Example 1 was carried out except that 200 g of diisoamyl ether was used as the C solvent in Example 1 to obtain crystals of m-aminophenol with a purity of 98.8%. I got 09.

Furthermore, by distilling these crystals under reduced pressure of 5 mmHP, m-aminophenol with a purity of 99.9% was obtained.
I was able to get a 9.

② From the diisoamyl ether layer obtained in the above ②, resorcinol 40.89 and m
-Amine Phenol (7.57 g) was recovered, and 69.2 v. of resorcinol and 91.2 g. g. of 28% aqueous ammonia were freshly charged thereto, and the reaction was carried out in the same manner as in Example-1.

As a result of GO analysis, a reaction mixture containing 44.2S' of resorcinol and 62.8y of m-7 minophenol was obtained, and the first reaction could be reproduced.

Comparative Example-1 Resorcinol 41.8P obtained by the same operation as Example-1,
m-7 minophenol58. Distillate containing OF is heated to 70℃
1009 in water and extracted twice with 2002 n-butyl ether at this temperature to obtain an aqueous layer.
The mixture was cooled to a temperature of 100.degree. C. to precipitate m-aminophenol.

The precipitated crystals were collected by filtration and dried at 60°C under reduced pressure to obtain 88.8P crystals with a purity of 98.2%. It was clear that the method of the present invention was significantly superior to both the purity and recovery rate of m-aminophenol.

Example-8 ■ Hydroquinone 11 (1' (1.0 mol) 2
91.22 mol of 8% ammonia water (1.5 mol of ammonia) was charged, and after purging with N2, the temperature was raised to 240°C and an amination reaction was carried out for 2 hours. After the reaction was completed, excess ammonia was removed by purging while cooling, and the reaction mixture was collected. As a result of GC analysis, hydroquinone 82.6F and p-
It contained 57.87 aminophenols.

The reaction mixture was transferred to an 800 mm pear-shaped flask, and water was first distilled off under a 200 x H9 vacuum, followed by distillation to remove heavy components under 2 ml (P2).

Distilled hydroquinone and p-aminophenol are Go
As a result of the analysis, it was 80.89.58.1 f't'.

Subsequently, this distillate and diisoamyl ether aoop as a solvent were charged into a separable flask of 1/l, and Ng
The distillate was brought into contact with the distillate for 15 minutes at 170"C while maintaining its molten state, and then cooled to 80°C to precipitate p-aminophenol. After separation, diisoamyl ether 80
02 and brought into melt contact for 170'C1b minutes,
Thereafter, the same operation as the first time was performed to obtain crystals of p-aminophenol. The weight of the crystals dried at 60°C under reduced pressure is 4
4.1? The purity of p-aminophenol is 9.
It was 9.4-.

(2) Using the entire amount of the diisoamyl ether layer from which p-aminophenol obtained in (1) was separated, the solvent was distilled off under reduced pressure of 200 mHp.

Unreacted hydroquinone was collected. The obtained still liquid contained 29.89 g of hydroquinone and 8.9 g of p-aminophenol.

Hydroquinone 80% is added to this recovered hydroquinone.
2 Ft- was added, 91.21 g of 28% ammonia water was added, and the amination reaction was carried out at 240°C for 2 hours after replacing with N2. The reaction mixture was then obtained in the same manner as in (1) above. As a result of GO analysis, 81.8P of hydroquinone and 66.8P of p-aminophenol were contained, and the first reaction could be reproduced.

Claims (1)

[Claims] 1) Reacting dihydric phenols with ammonia without a catalyst or in the presence of a water-soluble catalyst, and separating and recovering aminophenols and unreacted dihydric phenols from the reaction mixture after the reaction is completed. In the method in which the recovered dihydric phenols are recycled and used in the reaction, heavy components are removed by distillation from the reaction mixture after the reaction is completed to obtain a distillate, and the distillate is maintained in a molten state. The aminophenols are recovered by precipitation separation by contacting them with an aliphatic ether having a boiling point of 60°C or more and which is substantially incompatible with the aminophenols, and then the aliphatic ethers are distilled. 1. A method for producing aminophenols, which comprises allowing the distillate to be extracted and then circulating the distillate to a reaction system. 2) The method for producing aminophenols according to claim (1), wherein the aliphatic ether is n-butyl ether or diisoamyl ether. 3) The method for producing aminophenols according to claim (1), wherein the dihydric phenol is resorcinol or hydroquinone.