JPH0237910B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for separating and purifying aminophenols obtained by the reaction of divalent phenols and ammonia, and particularly to a method for separating and purifying high-quality aminophenols. Aminophenols have traditionally been widely used as intermediates for medicines, agricultural chemicals, azo dyes, antioxidants, and photographic agents, and have recently been used as raw materials for polyimide and polyamide heat-resistant resins. It is an extremely useful compound industrially. A method for producing aminophenols by reacting divalent phenols with ammonia without a catalyst or in the presence of a catalyst is known, but at that time, the reaction mixture contains other than the target aminophenols. It contained many unreacted divalent phenols and by-products. Without efficient separation of these components, especially when used in medicines, agricultural chemicals, etc., high-quality medicines, agricultural chemicals, etc. could not be produced due to these impurities. Therefore, conventionally a special purification process was required. Regarding the method of separating aminophenols, unreacted dihydric phenols, and/or byproducts from the reaction mixture to obtain purified aminophenols,
Several methods have been proposed. For example, (i) JP-A No. 48-28429 discloses that 2
A liquid-liquid extraction method using a water-diisopropyl ether solvent for crude aminophenols obtained by the reaction of phenols and ammonia is described. (ii) GB 1228568 describes a process in which crude p-aminophenol is contacted with liquid aliphatic, cycloaliphatic or aromatic ketones. (iii) GB 1028078 describes a process for washing crude p-aminophenol obtained by catalytic hydrogenation of nitrobenzene under acidic conditions with an aliphatic alcohol, preferably isopropanol. (iv) British Patent No. 1324787 states that crude p.
- A liquid-liquid extraction method of aminophenol using benzene, toluene, xylenes, and acetic acid esters and a water solvent is described. (v) British Patent No. 1291642 discloses that crude p.
-aminophenol carbon tetrachloride, 1,1,1
- A liquid-liquid extraction method using trichloroethane, 1,1-dichloroethane and a water solvent is described. (vi) JP-A-55-69543 describes a method of extraction by bringing crude p-aminophenol aqueous solution into contact with an aromatic amine. 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 divalent phenols and/or byproducts was still insufficient. In addition, I learned that methods (i) to (vi) are unsatisfactory in terms of yield. That is, in the method (i) above, since the solubility of aminophenols and divalent phenols in water is high, the separation efficiency of aminophenols and divalent phenols is low, and furthermore, the separation efficiency of aminophenols and divalent phenols is low. This resulted in losses and poor yields, and was economically disadvantageous. Also, (ii) above
The methods of ~(vi) are basically applied to p-aminophenol obtained by catalytic hydrogenation of nitrobenzene under acidic conditions, and are applied to p-aminophenol obtained by the reaction of divalent phenols and ammonia. Since the by-products are fundamentally different from the aminophenols used in the reaction, it has been difficult to separate the aminophenols from the unreacted divalent 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 found that a reaction mixture obtained by reacting divalent phenols with ammonia without a catalyst or in the presence of a water-soluble catalyst after the completion of the reaction. A separated and collected product containing aminophenols and unreacted divalent phenols was obtained, and this separated and collected product was
After contacting an aliphatic ether that is substantially incompatible with aminophenols under an inert gas atmosphere at a temperature higher than the temperature at which the separated and recovered material melts, the aminophenols are cooled to precipitate, and then over-recovered. Then, a cake containing aminophenols as the main component was obtained, and this cake was brought into melt contact again with an aliphatic ether under an inert gas atmosphere in the coexistence of water and a surfactant, and then cooled to obtain aminophenols. It has been discovered that the above object can be achieved by precipitating and collecting the above substances, and the present invention has been achieved. In the present invention, aminophenols, unreacted dihydric phenols, and/or byproducts can be efficiently separated from the reaction mixture, and the aminophenols obtained by separation are of high quality. That is, the present invention includes aminophenols and unreacted divalent phenols obtained by reacting divalent phenols with ammonia without a catalyst or in the presence of a water-soluble catalyst and separating and recovering from the reaction mixture after completion of the reaction. In separating and purifying aminophenols from the separated and recovered material, the separated and recovered material is mixed with an aliphatic ether that is substantially incompatible with the aminophenols under an inert gas atmosphere at a temperature higher than the temperature at which the separated and recovered material melts. After the contact, the aminophenols are cooled and precipitated, and then over-recovered,
A cake containing the aminophenols as a main component is obtained, and the cake is again melt-contacted with an aliphatic ether in an inert gas atmosphere in the coexistence of water and a surfactant, and then cooled to obtain the aminophenols. This is a method for separating and purifying aminophenols, which is characterized by precipitating and recovering aminophenols. Specifically, divalent phenols used as reaction raw materials include catechol, resorcinol, hydroquinone, 2-methylhydroquinone, 4-methyl-resorcinol, 5-methyl-resorcinol, 5-isopropylresorcinol, and 3-methyl-catechol. , 4-methylcatechol, 4-
Examples include tert-butylresorcinol and 4-tert-butylcatechol. Among these divalent phenols, it is preferable to use divalent phenols without substituents, and resorcinol or hydroquinone is particularly preferable. Further, the ammonia used can be used either as aqueous ammonia or as liquid ammonia. The proportion of ammonia used is preferably in the range of 0.5 to 10 moles per mole of divalent phenols. If it is less than 0.5 mol, the production of heavy components will increase, and if it exceeds 10 mol, the recovery load of ammonia will be significant, which will be extremely disadvantageous to the production of aminophenols, which is not preferable. The reaction between divalent 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. or,
The reaction is carried out under an ammonia atmosphere, but it is also possible to carry out the reaction under an inert gas atmosphere such as argon, helium or nitrogen. The separated and recovered material is obtained from the reaction mixture after the completion of the reaction.
It can be obtained by separating and recovering aminophenols and unreacted divalent phenols. Usually, the separated and recovered product also contains by-products (eg, aromatic diamines). The separated and collected material is distilled to remove substantially unreacted ammonia, water, and aminophenols from which heavy components have been removed, and unreacted 2
As a distillate containing monovalent phenols, and as a distillate containing aminophenols and unreacted divalent phenols from which substantially unreacted ammonia and water have been removed by distillation etc. In the case of a reaction mixture obtained after the reaction is carried out in the presence of a water-soluble catalyst, most of the unreacted ammonia is removed by distillation or the like, and then the catalyst aqueous layer is separated. It can be obtained as a separated product containing aminophenols and unreacted divalent phenols. According to the method of the present invention, highly pure aminophenols can be separated and purified from the thus obtained separated and collected product containing aminophenols and unreacted divalent phenols. In the method for separating and purifying aminophenols of the present invention, first, the separated and recovered material is stirred in an inert gas atmosphere with an aliphatic ether that is substantially incompatible with the aminophenols at a temperature higher than the temperature at which the separated and recovered material melts. After contacting with mixing, the aminophenols are selectively precipitated while cooling while stirring. At this time, unreacted divalent phenols are soluble in aliphatic ethers and are efficiently separated from aminophenols. The precipitated aminophenols are recovered as a cake through filtration operations such as reduced pressure, increased pressure, and centrifugation, and if necessary, operations can be performed to further improve the purity by rinsing with aliphatic ethers, etc. . Next, the cake containing aminophenols as a main component obtained in this way is mixed with aliphatic ethers again in the coexistence of water and a surfactant under an inert gas atmosphere at a temperature at which the cake melts. After contact under stirring and mixing, then while cooling under stirring,
Precipitates highly pure aminophenols. In this operation, divalent phenols that were not sufficiently separated in the first operation are removed by dissolving them in aliphatic ethers, and by-products (such as aromatic diamines) are removed.
Since it is soluble in water, it is removed in the aqueous layer, and highly purified aminophenols are precipitated. Furthermore, the surfactant has the remarkable effect of preventing the aminophenols from adhering to the vessel wall during precipitation of the aminophenols. Precipitated in this way,
The aminophenols are recovered as a cake by excessive operations such as reduced pressure, increased pressure, and centrifugation, and if necessary, further operations such as rinsing with aliphatic ethers can be performed to improve the purity. Depending on the purpose of use, this cake can be dried under reduced pressure to produce a product, or purified by distillation or the like to produce a product. The aliphatic ethers used in the present invention are substantially incompatible with aminophenols, and include dichloroethyl ether, dichloroisopropyl ether, diisopropyl ether,
Examples include di-n-butyl ether, diisoamyl ether, and ethylene glycol diethyl ether, with di-n-butyl ether and diisoamyl ether being particularly preferred. Precipitation of aminophenols and over-recovery of aminophenols by melt contact and cooling of the separated and recovered material containing aminophenols and unreacted dihydric phenols with aliphatic ethers, or a cake mainly composed of aminophenols and water. The precipitation of aminophenols by melt contact with aliphatic ethers and cooling in the presence of a surfactant, and the over-recovery operation are performed using an inert gas, For example, it is carried out under an atmosphere of argon, helium, nitrogen, or the like. In addition, depending on the melting temperature of the separated and recovered material and the cake mainly composed of aminophenols, and the boiling point of the aliphatic ether used,
The above operation can be carried out in any manner such as under increased pressure, normal pressure, reduced pressure, or a combination thereof. The appropriate amount of water to be used in the present invention is 5 to 100 parts by weight per 100 parts by weight of the cake; less than 5 parts by weight will result in insufficient removal of by-products, and more than 100 parts by weight will result in unreacted 2 This is not a good idea as the loss of valent phenols and aminophenols will be large. The type of surfactant is not particularly limited, and common surfactants such as cationic, anionic, amphoteric, and nonionic surfactants can be used, but nonionic surfactants are particularly preferred. The amount used is per 100 parts by weight of cake.
A range of 0.005 to 5 parts by weight is appropriate; if it is less than 0.005 parts by weight, the effect will not be sufficient, and if it exceeds 5 parts by weight, the effect will not change, so it is not a good idea. The separation and purification operation of the present invention is usually carried out more efficiently by using oil layers in series, as shown in Figure 1, for example. That is, in the separation and purification, the oil layer recovered in the separation and purification and the separated and recovered product are melt-contacted in an inert gas atmosphere, cooled, and then subjected to overoperation to obtain a cake containing aminophenols as the main component. Next, in separation and purification,
This cake is melt-contacted in an inert gas atmosphere with aliphatic ethers recovered from the oil layer by distillation or the like or fresh aliphatic ethers, and then cooled.
Then, through over-operation, a cake of highly pure aminophenols is obtained. The liquid is separated into an oil layer and an aqueous layer, and the oil layer is reused for separation and purification. Next, the method of the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. Example 1 110 g (1.0 mol) of resorcinol and 75.9 g (1.25 mol of ammonia) of 28% ammonia water were placed in a 500 c.c. stainless steel autoclave (equipped with a rotary stirrer), replaced with _N2 , and heated to 230°C. The amination reaction was carried out for 5 hours. After the reaction is completed, depressurize while cooling to purge excess ammonia, take out the reaction mixture, transfer it to a 300 c.c. three-necked pear-shaped flask, and remove remaining ammonia under reduced pressure of 100 mmHg. and water was substantially distilled off to obtain a separated product. Liquid chromatography analysis (LC)
Abbreviated as analysis. ) Results showed that 43.5 g of resorcinol, 54.3 g of meta-aminophenol, and 1.8 g of metaphenylenediamine were included as by-products. Subsequently, 200 g of this separated and recovered material and the solvent di-n-butyl ether (however, this contains 0.5 g of resorcinol)
Contains weight%. ) was placed in a separable flask and brought into melt contact at 100° C. for 15 minutes while maintaining the molten state of the separated and recovered product under N ₂ flow, and then cooled to 30° C. to precipitate meta-aminophenol. The precipitated meta-aminophenol was passed through a centrifuge (manufactured by Sanyo Rikagaku, Model 10A, same at 3000 rpm and below) to obtain a cake containing meta-aminophenol as a main component. Furthermore, add this cake and 200 g of new solvent di-n-butyl ether.
(However, it contains 0.5% by weight of resorcin) and 30g of water, 0.1g of surfactant (Emulgen 905 manufactured by Kao Atlas).
After charging and melt contacting at 90°C for 15 minutes, the same operation as the first time was performed to obtain a meta-aminophenol cake. In addition, during the cooling of the second operation, almost no meta-aminophenol was observed to adhere to the vessel wall. Further, this cake was distilled under reduced pressure to obtain 45.7 g of meta-aminophenol product. The purity of this meta-aminophenol was 99.7%. Example 2 After carrying out an amination reaction under the same conditions as in Example 1, water was distilled off under reduced pressure at 100 mmHg, and then at 5 mmHg.
Distillation to remove heavy components was carried out under reduced pressure. As a result of LC analysis, the obtained distillate contained 42.9 g of resorcinol,
It contained 53.7 g of meta-aminophenol and 1.6 g of metaphenylenediamine as a by-product. Subsequently, using this distillate, meta-aminophenol was separated and purified in the same manner as in Example 1. First, 250g of the solvent di-n-butyl ether (new solvent) and the distillate were brought into melt contact at 105℃ for 15 minutes under a _N2 seal, and then cooled to 30℃ to precipitate meta-aminophenol, which was then centrifuged to remove the methane. A cake containing aminophenol as the main component was obtained. Further, add this cake, 250 g of the solvent di-n-butyl ether (new solvent), 25 g of water, and 0.1 g of surfactant (Tween 20 manufactured by Kao Atlas), and after melting and contacting at 90°C for 15 minutes, repeat the same operation as the first time. A meta-aminophenol cake was obtained. During cooling in the second operation, almost no meta-aminophenol was observed to adhere to the vessel wall. This cake was dried at 60° C. under reduced pressure to obtain 46.1 g of meta-aminophenol product. The purity of this meta-aminophenol was 99.8%. Example 3 and Comparative Examples 1 to 3 A distillate obtained in the same manner as in Example 2 (containing 43.2 g of resorcinol, 54.0 g of meta-aminophenol, and 1.8 g of meta-phenylenediamine) was used in the second operation. The effects of water and surfactants were investigated. The separation and purification method was exactly the same as in Example 2 except that 200 g of di-n-butyl ether (new solvent) was used.

[Table] Comparative Example 4 Using exactly the same operation as in Example 2, during separation and purification,
When carried out without a _N2 seal, the resulting meta-aminophenol cake turned dark brown.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the flow of the separation and purification method. (Solvent indicates aliphatic ethers.)

Claims (1)

[Claims] 1. Aminophenols and unreacted divalent phenols obtained by reacting divalent phenols with ammonia without a catalyst or in the presence of a water-soluble catalyst and separating and recovering from the reaction mixture after the reaction is completed. When separating and purifying aminophenols from a separated and recovered product containing aminophenols, the separated and recovered product is mixed with an aliphatic ether that is substantially incompatible with the aminophenols under an inert gas atmosphere at a temperature higher than the temperature at which the separated and recovered product melts. After contacting with water, the aminophenols are precipitated by cooling, and then a cake containing the aminophenols as a main component is obtained by over-recovery, and the cake is heated with an inert gas in the coexistence of water and a surfactant. 1. A method for separating and purifying aminophenols, which comprises bringing them into melt contact with an aliphatic ether in an atmosphere, and then precipitating and recovering the aminophenols by cooling. 2. The method for separating and purifying aminophenols according to claim 1, wherein the aliphatic ether is di-n-butyl ether or diisoamyl ether. 3. Claim 1, characterized in that the amount of coexisting water is 5 to 100 parts by weight and the amount of surfactant is 0.005 to 5 parts by weight, based on 100 parts by weight of the cake.
A method for separating and purifying aminophenols as described in . 4. The method for separating and purifying aminophenols according to claim 1, wherein the divalent phenols are resorcinol or hydroquinone. 5. The method for separating and purifying aminophenols according to claim 1, wherein the surfactant is a nonionic surfactant.