JP2006206504A - Method for producing low-chlorine 3,4'-diaminodiphenyl ether - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing low-chlorine 3,4'-diaminodiphenyl ether, capable of directly reducing a reaction liquid of condensation of m-aminophenol and p-chloronitrobenzene which are used as raw materials, without passing through such a process that the reaction liquid is taken out of a reactor and then reduced. <P>SOLUTION: This method for producing the low-chlorine 3,4'-diaminodiphenyl ether comprises reducing 3-amino-4'-dinitrodiphenyl ether which is obtained by condensing the m-aminophenol and the p-chloronitrobenzene in a solvent by using 1.1 to 3 equivalents of a carbonic acid alkali metal salt as a condensing agent, so as to obtain 3,4'-diaminodiphenyl ether, then adding a lower aliphatic alcohol to the reaction liquid of the 3,4'-diaminodiphenyl ether in an amount of 40-150 mass% based on an amount of 100 mass% of the m-aminophenol, conducting solid-liquid separation, so as to obtain a separate liquid, and distilling the separate liquid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing low chlorine 3,4'-diaminodiphenyl ether used as a raw material or a modification additive for functional polyamide and polyimide.

  Since 3,4'-diaminodiphenyl ether is used as a raw material for functional polyamides and polyimides, if there are impurities such as moisture and halogen, these act as polymerization inhibitors, so it is required to reduce the content thereof. The Halogen is chlorine derived from p-chloronitrobenzene as a raw material, and the amount thereof is preferably smaller, and 10 ppm or less is required.

Conventionally, 3,4'-diaminodiphenyl ether is obtained by thermally reacting m-aminophenol and p-chloronitrobenzene with a condensing agent such as potassium carbonate to obtain 3-amino-4'-nitrodiphenyl ether as an intermediate. It was obtained by reduction and purification by distillation. In the condensation reaction, chlorine derived from p-chloronitrobenzene is deposited as an alkali metal salt of a condensing agent. In the subsequent reduction reaction, the condensation reaction solution was once poured into water to obtain an intermediate as crystals (see Patent Document 1, Examples), or the condensation reaction solution was filtered to remove the alkali metal salt (patent) Reference 2, Example). In this method, when catalytic reduction with hydrogen is performed as a reduction reaction, chlorine ions can be removed at the same time as alkali metal ions which are catalyst poisons thereof, so that low chlorine 3,4′-diaminodiphenyl ether is produced. It was a necessary process. However, these methods are not sufficiently streamlined processes because some or all of the condensation reaction solution needs to be removed from the reactor before the reduction reaction.
Japanese Patent Publication No. 8-9581 JP-A-6-219999

  The object of the present invention is to produce a 3,4′-diaminodiphenyl ether using m-aminophenol and p-chloronitrobenzene as raw materials, and to remove the condensation reaction solution of m-aminophenol and p-chloronitrobenzene from the reactor. The object is to propose a method that enables direct reduction without going through a reduction step.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has made it possible to directly reduce without going through a step of removing the condensation reaction solution of m-aminophenol and p-chloronitrobenzene from the reactor and reducing it. In addition, the present inventors have found a method for producing low chlorine 3,4′-diaminodiphenyl ether capable of easily removing chlorine ions in a subsequent process, and have reached the present invention.

  Specifically, by using hydrazine as a reducing agent and using a trivalent iron compound having no poisoning action as a catalyst, it is not necessary to take out the intermediate as described above, and low chlorine 3, 4'-diaminodiphenyl ether can be obtained.

That is, the present invention has the following configuration.
(1) Reduction of 3-amino-4′-nitrodiphenyl ether obtained by condensing m-aminophenol and p-chloronitrobenzene in a solvent using 1.1 to 3 equivalents of alkali metal carbonate as a condensing agent To 3,4'-diaminodiphenyl ether, and 40 to 150% by mass of a lower aliphatic alcohol is added to 100% by mass of m-aminophenol in the reaction solution of 3,4'-diaminodiphenyl ether, followed by solid-liquid separation. A method for producing low chlorine 3,4′-diaminodiphenyl ether, wherein the separated liquid after distillation is distilled.
(2) The reaction solution of 3,4'-diaminodiphenyl ether described in (1) is subjected to solid-liquid separation, and the solid after separation is 40 to 150% by mass of a lower fat with respect to 100% by mass of m-aminophenol. A method for producing low chlorine 3,4'-diaminodiphenyl ether, comprising: mixing a cleaning solution washed with an aromatic alcohol and a separated solution after solid-liquid separation, and then distilling the mixed solution.
(3) The method for producing low chlorine 3,4'-diaminodiphenyl ether according to (1) or (2), wherein the lower aliphatic alcohol is any one of methanol, ethanol, 2-propanol or a mixture thereof. .

  According to the present invention, m-aminophenol and p-chloronitrobenzene are condensed, and after reducing directly without taking out the condensation reaction solution, low chlorine 3,4′-diaminodiphenyl ether is efficiently obtained by distillation. Obtainable.

The present invention will be described along a manufacturing procedure.
The reaction for condensing m-aminophenol and p-chloronitrobenzene is performed using an alkali metal carbonate in a solvent. The solvent is preferably an aprotic polar solvent. Specific examples include dimethylformamide and dimethyl sulfoxide.

The alkali metal carbonate that is a condensing agent is preferably potassium carbonate or sodium carbonate. The amount of the condensing agent used is 1.1 to 3 times, preferably 1.1 to 2 times the equivalent. If it is less than 1.1 times, the reaction rate is lowered, which is not preferable. If it exceeds 3 times, there is no effect of improving the reaction rate.
In condensing m-aminophenol and p-chloronitrobenzene, both are generally reacted in equimolar amounts, and this is also preferable because no unreacted product remains.

Next, the process of reducing the reaction liquid after the condensation reaction will be described.
As a catalyst used for the reduction, a trivalent iron compound is preferably used. The trivalent iron compound may be iron (III) chloride powder, iron chloride (III), or iron hydroxide (III). These trivalent iron compounds are preferred because they are less susceptible to catalyst poisoning by alkali metal ions. As a specific method of the direct reduction reaction, a trivalent iron compound and activated carbon are added to a condensation reaction solution of m-aminophenol and p-chloronitrobenzene, and direct reduction is performed using hydrazine. The conventional catalytic reduction method using hydrogen is not preferable because it is not efficient and economically disadvantageous because the life of the catalyst used is short.

  The condensation reaction solution of m-aminophenol and p-chloronitrobenzene is directly reduced by the above method, but in the presence of excess alkali metal carbonate. This is because an alkali metal carbonate has an effect of reducing chlorine in the distillation process. Therefore, the reason why the amount of the condensing agent used is 1.1 times or more with respect to the equivalent is not only for improving the reaction rate.

  The subsequent filtration step will be described. In a reaction liquid obtained by condensing m-aminophenol and p-chloronitrobenzene using an alkali metal carbonate as a condensing agent, a reaction product, 3-amino-4′-nitrodiphenyl ether, and a condensing agent as chlorine. The alkali metal chloride obtained by the reaction, the solvent, and the unreacted alkali metal carbonate are mixed. This is directly used for reduction. Accordingly, since a precipitate of alkali metal chloride is present in the reaction solution after direct reduction, it must be removed by solid-liquid separation in the filtration step.

  In the filtration step, alcohol is added as a filter aid to the reaction solution after direct reduction, and the separated liquid (filtrate) after solid-liquid separation is connected to the next distillation step, or the reaction solution after direct reduction is added first. After the solid-liquid separation, there is a method in which a washing liquid obtained by washing the separated solid with alcohol and a separated liquid (filtrate) after solid-liquid separation are mixed and the mixed liquid is connected to the next distillation step. In the present invention, either method may be used.

  The usage-amount of alcohol is 40 mass%-150 mass% with respect to 100 mass% of raw material m-aminophenol, Preferably it is 40 mass%-90 mass%. This alcohol has a role of reducing the viscosity of the reaction solution after direct reduction to perform smooth filtration and dissolving the alkali metal carbonate in the reaction solution. The alkali metal carbonate dissolved in the filter aid is effective in reducing chlorine in the subsequent distillation step. If the amount added is less than 40% by mass, the amount of alkali carbonate carbonate dissolved is small, so the effect of reducing chlorine is ineffective. If it exceeds 150% by mass, a large amount of energy is required for distillation, which is economically disadvantageous.

  As the alcohol used in the present invention, lower aliphatic alcohols such as methanol, ethanol and 2-propanol are preferably used, and methanol is most preferable. Alcohols other than this, such as butanol, are also effective, but the ability to dissolve alkali metal carbonate salts is reduced, so the amount of alcohol used is increased, which is disadvantageous in terms of energy and economy.

  The filtrate obtained as described above (the separation liquid after adding alcohol to the reaction liquid after the reduction, or the separation liquid after washing the solid with alcohol after solid-liquid separation and the separation liquid after solid-liquid separation) In the mixture (including both of the mixture), the product, 3,4′-diaminodiphenyl ether, solvent, alcohol and a small amount of alkali metal carbonate are mixed. By distilling them, the alcohol and solvent are distilled first, followed by 3,4'-diaminodiphenyl ether. In this way, low chlorine 3,4'-diaminodiphenyl ether can be obtained.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. These results are shown in Tables 1-1 and 1-2.
Example 1
In a 200 ml flask equipped with a stirrer, 22.1 g (0.2 mol) of m-aminophenol, 31.8 g (0.2 mol) of p-chloronitrobenzene, and 15.5 g (1.1 mol) of potassium carbonate as a condensing agent were used. Equivalent) and 53.9 g of dimethyl sulfoxide as a solvent, and reacted at 140 ° C. for 5 hours.
To this condensation reaction solution, 2.2 g of activated carbon and 1.1 g (0.02 mol) of iron (III) chloride were added, and hydrazine was added dropwise to react for 3 hours, and the completion of the reduction was confirmed by gas chromatography (GC) method. did. Thereafter, the reaction solution is cooled, and 9 g of methanol (40% by mass with respect to 100% by mass of m-aminophenol) is added as a filter aid solution, followed by distillation. 45.3 g of 4′-diaminodiphenyl ether was obtained.
The chlorine concentration of this 3,4'-diaminodiphenyl ether was 4 ppm.

Example 2
The same as Example 1 except that the condensing agent was replaced with sodium carbonate.
Example 3
The same as Example 1, except that the amount of the condensing agent used was 1.4 equivalents.
Example 4
Example 1 is the same as Example 1 except that methanol is replaced with ethanol.
Example 5
The same as Example 1 except that methanol was replaced with 2-propanol.
Example 6
Example 1 is the same as Example 1 except that the amount of the filter aid is 55% by mass.

Comparative Example 1
Example 1 is the same as Example 1 except that a 1.0-fold equivalent of condensing agent was used.
In this case, since the reaction rate decreases, the yield is low at the same reduction reaction time.
Comparative Example 2
The same as Comparative Example 1, except that the reaction time was tripled to 9 hours.
Even in this case, the yield is low, and the purity of 3,4'-diaminodiphenyl ether is also low.
Comparative Example 3
The same procedure as in Example 1 except that the amount of the filter aid (methanol) was 30% by mass with respect to 100% by mass of m-aminophenol.
Since the amount of the filter aid is small, the chlorine concentration in 3,4'-diaminodiphenyl ether is slightly high.
Comparative Example 4
This is an example in which no filter aid is used, and the others are the same as in Example 1.
The chlorine concentration in 3,4'-diaminodiphenyl ether is very high.

  From the above results, in order to reduce the chlorine concentration in 3,4'-diaminodiphenyl ether and at the same time to obtain 3,4'-diaminodiphenyl ether in good yield, an excessive use of a condensing agent and a filter aid It is recognized that it is necessary to use more than a certain amount.

According to the method for producing low chlorine 3,4′-diaminodiphenyl ether of the present invention, the production process can be simplified, and in particular, a condensation reaction solution obtained from m-aminophenol and p-chloronitrobenzene in the reduction reaction step is used as a reactor. Direct reduction is possible without taking it out of the box. The obtained 3,4'-diaminodiphenyl ether has a low chlorine content and has almost no polymerization inhibitor, so it can be used as a raw material for functional polyamides and polyimides.

Claims (3)

  3-amino-4′-nitrodiphenyl ether obtained by condensing m-aminophenol and p-chloronitrobenzene in a solvent using 1.1 to 3 equivalents of an alkali metal carbonate as a condensing agent is reduced to 3 , 4'-diaminodiphenyl ether, and 40 to 150% by mass of a lower aliphatic alcohol is added to the reaction solution of 3,4'-diaminodiphenyl ether with respect to 100% by mass of m-aminophenol, followed by solid-liquid separation. A process for producing low chlorine 3,4'-diaminodiphenyl ether, wherein the separated liquid is distilled.   The reaction solution of 3,4'-diaminodiphenyl ether according to claim 1 is subjected to solid-liquid separation, and the separated solid is mixed with 40 to 150% by mass of a lower aliphatic alcohol based on 100% by mass of m-aminophenol. A method for producing low chlorine 3,4′-diaminodiphenyl ether, which comprises additionally mixing a washed washing solution and a separated liquid after solid-liquid separation, and then distilling the mixed solution. The method for producing low chlorine 3,4'-diaminodiphenyl ether according to claim 1 or 2, wherein the lower aliphatic alcohol is any one of methanol, ethanol, 2-propanol or a mixture thereof.