JPH0227981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing aminodiphenyl ethers. Aminodiphenyl ethers obtained by the present invention can be used as raw materials for dyes, medicines, agricultural chemicals, synthetic resins,
Useful as a difunctional crosslinker and network extender for plastics and elastomers. Conventionally, as a method for producing aminodiphenyl ethers, a method in which nitrodiphenyl ethers are reduced with hydrogen in a liquid phase has been widely adopted.
In order for this hydrogen reduction reaction to proceed smoothly,
Generally, a method is adopted in which a solvent soluble in the raw material nitrodiphenyl ether is used and the reaction is carried out under homogeneous liquid phase conditions. A method using dimethylformamide as a solvent having high solubility for ethers and aminodiphenyl ethers has been proposed. However, since dimethylformamide is freely miscible with the water produced by the hydrogen reduction reaction, it has the disadvantage that water must be separated and removed by distillation in order to use this solvent repeatedly. As an improved method of this method, JP-A-54-
Publication No. 88228 and Japanese Unexamined Patent Application Publication No. 106439/1988,
Glycol monoether monoesters such as 2-ethoxyethyl acetate, or dioxane are used as solvents that have high solubility in nitrodiphenyl ethers and aminodiphenyl ethers and are immiscible with the water produced in the hydrogen reduction reaction. , methods using cyclic ethers of tetrahydrofurans, or fatty acid esters such as ethyl acetate have been proposed. This method has the advantage that the solvent can be recycled and reused by removing the produced water from the solvent through a simple operation called oil-water separation, but it is difficult to separate aminodiphenyl ethers, which are hydrogen reduction reaction products. In this case, there is a drawback that the solvent as well as the catalyst must be removed from the reduction reaction mixture obtained after the completion of the hydrogen reduction reaction by a complicated operation called distillation. The present inventors recognized that the previously proposed liquid phase hydrogen reduction reaction method of nitrodiphenyl ethers in a homogeneous system has the above-mentioned drawbacks, and they As a result of intensive studies on methods that can separate diphenyl ethers, we found that the above objective can be achieved by forming a heterogeneous system in the reaction system in the presence of a solvent that is poorly soluble in the raw material nitrodiphenyl ethers. We have discovered that this can be achieved, and have arrived at the present invention. That is, to summarize the present invention, the present invention involves contacting nitrodiphenyl ethers with hydrogen in the presence of a hydrogen-reducing catalyst to reduce a nitro group to an amino group to produce corresponding aminodiphenyl ethers. In the method for producing nitrodiphenyl ether, a solvent that is poorly soluble in the nitrodiphenyl ether is present under hydrogen reduction reaction conditions, and the hydrogen is removed while forming a heterogeneous mixture consisting of the nitrodiphenyl ether and the solvent. The gist of the invention is a method for producing aminodiphenyl ethers, which comprises performing a reduction reaction to obtain a heterogeneous reaction product mixture, and separating aminodiphenyl ethers by phase-separating the reaction product mixture. It is something. This will be explained in detail below. The nitrodiphenyl ethers used in the process of the invention are diphenyl ethers having at least one nitro group or substituted products thereof, such as 3-amino-4'-nitrodiphenyl ether, 3-amino-3 '-Nitrodiphenyl ether, 4-amino-4'-nitrodiphenyl ether, 4-amino-3'-nitrodiphenyl ether, 2-amino-4'-nitrodiphenyl ether, 2-amino-3'- Nitrodiphenyl ether, 2-amino-2'-nitrodiphenyl ether, 2-nitrodiphenyl ether, 3-nitrodiphenyl ether, 4-nitrodiphenyl ether, 3,4'-dinitrodiphenyl ether,
2,4'-dinitro diphenyl ether, 4,4'-
Dinitro diphenyl ether, 4-chloro-4'-
Nitrodiphenyl ether, 2-chloro-4'-nitrodiphenyl ether, 4-chloro-3'-nitrodiphenyl ether, 4-bromo-2'-nitrodiphenyl ether, 4-methyl-4'-nitrodiphenyl ether enyl ether, 2-chloro-5-methyl-
4'-Nitrodiphenyl ether, 3-(N,N-
dimethylamino)-4'-nitrodiphenyl ether, 3-(N,N-dimethylamino)-3'-nitrodiphenyl ether, 4-(N,N-dimethylamino)-4'-nitrodiphenyl ether, 4-
(N,N-dimethylamino)-3'-nitrodiphenyl ether, 3-(N,N-diethylamino)-
4'-Nitrodiphenyl ether, 3-(N,N-
diethylamino)-3'-nitrodiphenyl ether, 4-(N,N-diethylamino)-4'-nitrodiphenyl ether, 4-(N,N-diethylamino)-3'-nitrodiphenyl ether, etc. Can be done. The catalyst for hydrogen reduction used in the method of the present invention is, for example, a metal of group 3 of the periodic table, such as Raney nickel, Raney cobalt, platinum oxide, platinum, palladium, or rhodium, or a compound of the metal, which has an active property for the hydrogen reduction reaction. The catalyst used as a component can be mentioned. These active ingredients can be used in various carriers, such as alumina, diatomaceous earth, activated carbon, inorganic or organic fibers, calcium carbonate, silica, silica-alumina, barium sulfate,
It may be supported on a metal oxide such as titanium oxide, a metal salt, or an organic polymeric resin, or the active ingredient may be used alone. Among these catalysts, it is desirable to use a palladium catalyst that is highly active at low temperatures, particularly a palladium catalyst supported on a carrier such as activated carbon or alumina. The state of palladium before using the catalyst in the hydrogen reduction reaction may be palladium black (metal), oxide, or halide, but in the hydrogen reduction reaction, in particular, palladium in the form of metal dispersed in the carrier Black is better. The amount of palladium supported on the palladium catalyst supported on the above-mentioned carrier is usually in the range of 0.5 to 5% by weight in terms of metal palladium (metal palladium weight/support weight) based on the dry weight of the support (drying at 120°C). It is better to have it in In the method of the present invention, the sparingly soluble solvent used in the hydrogen reduction reaction is a solvent that is sparingly soluble for the nitrodiphenyl ethers under hydrogen reduction conditions, and forms a heterogeneous mixture in the reaction system. In addition, it is a solvent that forms a heterogeneous reaction product mixture even after the reaction is completed, and more preferably a solvent that is sparingly soluble in both the nitrodiphenyl ethers and the aminodiphenyl ethers. , a solvent that forms a heterogeneous mixture in the reaction system and also forms a heterogeneous reaction product mixture after the reaction is completed. Specific examples of the poorly soluble solvent include water, aliphatic hydrocarbons such as hexane and heptane, and alicyclic hydrocarbons such as cyclohexane and decalin. These poorly soluble solvents may be used alone or in combination, but among these poorly soluble solvents, water is preferably used. The amount of the poorly soluble solvent used is usually 50 parts by weight per 100 parts by weight of the nitrodiphenyl ether.
It is advisable to use 1000 to 1000 parts by weight, preferably 100 to 400 parts by weight. In the method of the present invention, the hydrogen reduction reaction is carried out by contacting a heterogeneous mixture consisting of the raw material nitrodiphenyl ethers and the poorly soluble solvent with hydrogen in the presence of the hydrogen reduction catalyst. Here, the term "heterogeneous mixture" refers to a state in which the nitrodiphenyl ethers are dispersed in the poorly soluble solvent, and may form a one-liquid heterogeneous mixture, or a solid-liquid heterogeneous mixture. Although a system mixture may be formed, it is preferable that a one-liquid heterogeneous mixture is formed. During the reaction, these heterogeneous mixtures are preferably in a finely dispersed state under stirring. In the method of the present invention, the hydrogen reduction reaction is carried out by suspending the hydrogen reduction catalyst in a heterogeneous mixture consisting of the nitrodiphenyl ethers and the poorly soluble solvent, and introducing hydrogen. good. In this case, the amount of hydrogen reduction catalyst to be used is usually 0.01 to 1 g, preferably 0.05 to 0.5 g, expressed as metal palladium, based on palladium, which is a catalytically active component excluding the carrier, per 1 of the mixed liquid. Good to use. The hydrogen pressure when carrying out the hydrogen reduction reaction is usually 0.5 to 150 kg/absolute pressure.
cm ² , preferably in the range of 1 to 100 kg/cm ² absolute pressure. In this case, in addition to the method of using hydrogen alone, an inert gas such as nitrogen, helium, or argon may be used together with hydrogen. When carrying out the hydrogen reduction reaction in the method of the present invention, any reaction method can be applied, such as a batch method, a semi-batch method, or a continuous method, as long as it is equipped with a hydrogen inlet and a stirring device. You may use a container. A commonly known stirring method can be used to contact the heterogeneous mixture of the nitrodiphenyl ethers and the poorly soluble solvent and the catalyst suspended in the heterogeneous mixture with hydrogen. can. Specifically, a stirring blade method in which stirring blades are rotated or vibrated, a stirring method in which inert gas is jetted out from the bottom of the reactor, or a method in which liquids are stirred using ultrasonic waves, etc. Methods such as stirring by vibration or fluidization can be adopted. In the method of the present invention, the reaction temperature for the hydrogen reduction reaction varies depending on the type of nitrodiphenyl ether, but is usually in the range of 50 to 200°C, preferably 80 to 160°C. Although the reaction time varies somewhat depending on the reaction pressure, amount of catalyst, reaction temperature, stirring method, etc., it is usually sufficient to carry out the reaction within a range of 0.5 to 15 hr, preferably 1 to 8 hr. In the method of the present invention, as a result of the hydrogen reduction reaction,
The nitro group of the nitrodiphenyl ether is reduced to an amino group to form the corresponding aminodiphenyl ether, yielding a heterogeneous reaction product mixture. The heterogeneous reaction product mixture contains the aminodiphenyl ether, the poorly soluble solvent, and the unreacted nitrodiphenyl ether in addition to the catalyst. The heterogeneous reaction product mixture consists of a liquid phase mainly consisting of the poorly soluble solvent and a phase consisting of a mixture of the aminodiphenyl ethers and the unreacted nitrodiphenyl ethers (hereinafter, this phase is referred to as a reduction product mixture phase). ), and the catalyst. The separation of the aminodiphenyl ethers obtained by the method of the present invention is carried out in a state in which the heterogeneous reaction product mixture is made into a two-liquid phase mixture in which an insoluble catalyst is suspended, that is, the reduction product mixture phase is converted into a liquid phase. This can be carried out by a separation method of separating the phases of the reduction product oil (hereinafter sometimes referred to as reduction product oil). In this case, as a method for converting the heterogeneous reaction product mixture into the two liquid phases, the following methods can be selected as appropriate. The heterogeneous reaction product mixture is maintained at a temperature at which the heterogeneous reaction product mixture forms the two-liquid phase mixture, that is, the reduction product mixture phase does not form a solid mass and precipitate. When water is used as the sparingly soluble solvent, a suitable amount of a water-insoluble solvent such as toluene or xylene may be added to the heterogeneous reaction product mixture to prepare a solvent-added heterogeneous reaction product mixture. In this case, the mixture is maintained at a temperature at which the solvent-added heterogeneous reaction product mixture forms a two-liquid phase mixture. The phase separation operation in the method of the present invention can be carried out, for example, by a conventional method utilizing a difference in specific gravity, such as oil/water separation. In this case, a filter is used during the phase separation operation to simultaneously separate and remove the catalyst mixed in the reduction product oil or the reduction product oil containing the solvent (hereinafter sometimes referred to as reduction product oil, etc.). It's okay. In separating the reduction product oil, etc., the catalyst in the two-liquid phase mixture may be removed by filtration or the like, and then the reduction product oil, etc. may be phase-separated. Regarding the method of separating the reduction product oil containing the aminodiphenyl ethers, in addition to the method of converting the heterogeneous reaction product mixture into a two-liquid phase mixture described above, the following method may be used as necessary. can be done. That is, in a state where the reduction product mixture phase in the heterogeneous reaction product mixture is precipitated as a solid lump containing the catalyst, after separating the precipitate, a solvent such as toluene or xylene is added to the precipitate. The reduced product oil containing the solvent is obtained by adding an appropriate amount of the reduced product mixture phase to dissolve the reduced product mixture phase to obtain a mixed solution containing the solvent, and then removing the catalyst from the mixed solution by filtration or the like. can be obtained. The reduction product oil etc. can be obtained by any of the above methods. The reduced oil, etc. may be washed with the poorly soluble solvent, if necessary. In the method of the present invention, the heat retention temperature of the heterogeneous reaction product mixture and the heat retention temperature of the solvent-added heterogeneous reaction product mixture shown in and above, which are used in the phase separation operation, are as follows. Although it varies depending on the type of nitrodiphenyl ether used in the hydrogen reduction reaction, it is usually 70
to 190℃. For example, when 3-amino-4'-nitrodiphenyl ether is used as the nitrodiphenyl ether, the insulating temperature is preferably in the range of 70 to 90°C. The catalyst recovered by the above separation operation is
If necessary, it may be washed with the poorly soluble solvent, and after such operation, it may be washed with a solvent such as methanol, if necessary, and then used again. In addition, the recovered liquid mainly consisting of a poorly soluble solvent recovered by the phase separation operation may be used as it is, or if necessary, a part of the recovered liquid may be replaced with fresh the hardly soluble solvent. It can be reused as a solvent for the hydrogen reduction reaction. The desired aminodiphenyl ethers with high purity can be obtained by treating the reduction product oil and the like by a conventional method such as distillation or crystallization, if necessary. The method of the present invention will be explained in more detail with reference to Examples below. Example 1 3-amino-4'-nitrodiphenyl ether
50g, water 50g and 5% Pd/c 0.5g with induction stirrer
It was placed in a 500ml autoclave (made of SUS32).
After pressurizing with hydrogen to 30 Kg/cm ² G, a reduction reaction was carried out at a reaction temperature of 90°C. As the reaction progressed, hydrogen was consumed (pressure decreased), so hydrogen was replenished from the hydrogen supply pipe connected to the autoclave, and the pressure was always maintained at 30 Kg/cm ² G. After 5 hours of reaction, the autoclave was cooled to 75°C, opened, and the entire contents were transferred to a 500 ml double-tube glass container. While the contents of the glass container were maintained at 75° C. or higher, the oil phase (reduction product oil) was extracted from the bottom of the container to separate the product and the solvent. At this time, the catalyst contained in the oil phase was also removed using a suitable filter. The obtained crude 3,4'-diaminodiphenyl ether was purified by distillation under conditions of 2 mmHg and 200°C. The amount of 3,4'-diaminodiphenyl ether obtained was 42.6g.
The yield was 98 mol% based on 3-amino-4'-nitrodiphenyl ether. Example 2 Crude 2,3'-diaminodiphenyl ether was obtained by the same method and operating conditions as in Example 1, except that the raw material was changed to 2-nitro-3'-aminodiphenyl ether. Next, this crude 2,3'-diaminodiphenyl ether was distilled under conditions of 7 mmHg and 200°C to form 2,3'-diaminodiphenyl ether.
Obtained 41.5g. In this case, the yield based on the raw material was 95 mol%. Example 3 4-amino-4'-nitrodiphenyl ether
25 g, water 150 g, and 5% Pd/c 0.2 g were charged into a 500 ml autoclave (made of SUS32) equipped with an induction stirrer. After pressurizing with hydrogen to 40Kg/cm ² G, the reaction temperature
The reduction reaction was carried out at 190°C for 1 hour. Hydrogen consumed as the reaction progressed was replenished in a timely manner. Immediately after the reaction was completed, 250 ml of toluene was introduced under pressure. Next, the autoclave was cooled to 80° C., the autoclave was opened, the contents were taken out, and the oil phase and the water phase were separated. After removing the catalyst, the oil phase was left to cool while stirring to precipitate crystals. The crystals of 4,4'-diaminodiphenyl ether obtained by filtering and drying the precipitated crystals were 18.9 g, and the yield was 87 mol% based on 4-amino-4'-nitrodiphenyl ether. It was hot.
Further, 1.7 g of 4,4'-diaminodiphenyl ether was recovered from the liquid at this time. Examples 4 and 5 The types of nitrodiphenyl ethers used as raw materials are shown in Table 1.
Diaminodiphenyl ether was obtained by the same method and operating conditions as in Example 3, except for the following changes. The results in this case are shown in Table 1. 【table】

Claims (1)

[Claims] 1 In a method for producing a corresponding aminodiphenyl ether by reducing a nitro group to an amino group by contacting a nitrodiphenyl ether with hydrogen in the presence of a hydrogen reduction catalyst, under hydrogen reduction reaction conditions. In the presence of a poorly soluble solvent for the nitrodiphenyl ethers, the hydrogen reduction reaction is performed while forming a heterogeneous mixture consisting of the nitrodiphenyl ethers and the solvent, and the heterogeneous reaction product mixture is 1. A method for producing aminodiphenyl ethers, which comprises separating the aminodiphenyl ethers by phase-separating the heterogeneous reaction product mixture.