JP2006206544A - Method for purifying diaminodiphenyl ether - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently purifying diaminodiphenyl ether which is used as a raw material for a functional polyamide and polyimide with high purity. <P>SOLUTION: This method for purifying the diaminodiphenyl ether comprises washing the diaminodiphenyl ether with water, wherein any one of benzene, toluene, or xylene, or a mixture thereof, is added as a washing auxiliary agent to the water used for washing in an amount of 2 to 5 times larger than a mass of the diaminodiphenyl ether. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for purifying diaminodiphenyl ether used as a raw material or modifying additive for functional polyamide and polyimide.

Since diaminodiphenyl ether is used as a raw material for functional polyamide and polyimide, it is preferable that impurities such as isomers, monoamines and halogens are less.
In general production method of diaminodiphenyl ether, aminophenol and chloronitrobenzene are condensed to obtain aminonitrodiphenyl ether as an intermediate, and then reduced to obtain crude diaminodiphenyl ether. And in order to raise purity, the method by distillation or the method of throwing in water and taking out as a crystal | crystallization is performed, However, It is inadequate as a method of obtaining high purity diaminodiphenyl ether.

  As for 3,4'-diaminodiphenyl ether, it is disclosed that a high-purity product is obtained by reducing the isomers of the raw material (see Patent Document 1). In this case, impurities derived from side reactions that occur during production cannot be removed.

  Furthermore, a method of distilling crude diaminodiphenyl ether by adding an inert organic solvent having a boiling range of 240 to 350 ° C. is disclosed (see Patent Document 2). As shown in the examples, this method is based on the premise that a distillation column is provided for distillation, and the degree of purification is increased by reflux. That is, an apparatus and operation capable of sharply cutting the first fraction and the added organic solvent are required, and the time required for distillation is increased by the reflux operation, and a large amount of heat energy is required.

In order to suppress side reactions during distillation, the reaction solvent was distilled off within 8 hours under the conditions of a tower top temperature of 60 to 150 ° C. and a tower top pressure of 1.3 to 266.6 hectopascals. A method for distilling diaminodiphenyl ether under a pressure of 66.6 hectopascals or less has been proposed (see Patent Document 3). This method, when dimethylformamide (DMF) or N-methylpyrrolidone (NMP) is used as a solvent, is a method for reducing compounds (amidines) produced as a side reaction involving a solvent during a reduction reaction. Is effective, but when dimethyl sulfoxide (DMSO) is used as a solvent, a side reaction occurs during the condensation reaction, so it is not effective as a method for reducing this.
Japanese Patent Publication No. 8-9581 Japanese Patent Publication No. 6-35425 JP-A-8-27077

  An object of the present invention is to propose a method for efficiently purifying diaminodiphenyl ether, which is a raw material for functional polyamide and polyimide.

  As a result of intensive studies to solve the above problems, the present inventors have found a method for purifying diaminodiphenyl ether by elucidating the main components of impurities in diaminodiphenyl ether and efficiently removing them, leading to the present invention. It was.

  Specifically, in order to elucidate the impurities in diaminodiphenyl ether, diaminodiphenyl ether was used as a raw material for the polymerization of polyamide and polyimide, and as a result of investigating the relationship between the degree of polymerization of the obtained polyamide and polyimide and the impurities, monoamine and moisture Was found to be the main component of impurities. Among the monoamines, methyl mercaptoaniline was found to act as an inhibitor of polymerization even in a very small amount. Other monoamines are low-boiling monoamines and have a higher partition coefficient with respect to water than diaminodiphenyl ether, and it was confirmed by experiments that diboiling monoamines can be removed by washing with diaminodiphenyl ether.

That is, the present invention has the following configuration.
(1) When diaminodiphenyl ether is washed with water and purified, either benzene, toluene or xylene or a mixture thereof is added to the washing water as a washing aid in a mass ratio of 2 to 6 times that of diaminodiphenyl ether. And a method for purifying diaminodiphenyl ether.
(2) The method for purifying diaminodiphenyl ether according to (1) above, wherein the diaminodiphenyl ether is 4,4′-diaminodiphenyl ether or 3,4′-diaminodiphenyl ether.
(3) The method for purifying diaminodiphenyl ether according to (1) above, wherein the diaminodiphenyl ether is distilled diaminodiphenyl ether.

  According to the present invention, impurities in diaminodiphenyl ether can be removed by washing with water to which a cleaning aid has been added, and high purity of diaminodiphenyl ether can be achieved. The diaminodiphenyl ether thus obtained does not contain impurities that serve as polymerization inhibitors and can therefore be used as a raw material for functional polyamides and polyimides.

Next, the present invention will be described in detail with reference to preferred embodiments.
As the diaminodiphenyl ether purified by the present invention, those in the form of oxydianiline such as 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether can be used, preferably 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether. 4'-diaminodiphenyl ether.

  A general method for producing diaminodiphenyl ether in the present invention is a method in which aminophenol and chloronitrobenzene are condensed in a solvent using a condensing agent. As the solvent used for the condensation reaction, dimethylformamide (DMF), N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO) are used. Among these, it is preferable to use dimethyl sulfoxide which does not decompose at the reaction temperature and hardly evaporates, but a trace amount of methyl mercaptoaniline is produced. A crude diaminodiphenyl ether is obtained by reducing the condensate aminonitrodiphenyl ether. Although this is purified by distillation, it is not sufficiently pure. In the distillation operation, the column top temperature is 183 ° C. if the column top pressure is 1.3 hectopascals.

  Although the melting point of diaminodiphenyl ether is about 80 ° C. depending on the type, it is difficult to perform an industrial water washing operation because of its high viscosity. Therefore, when washing with water, it is necessary to add a washing aid to diaminodiphenyl ether to lower the viscosity. As a cleaning aid for that purpose, benzene, toluene or xylene is preferable from the viewpoints of water insolubility, affinity with diaminodiphenyl ether, low toxicity, easy handling, and economic effects. Among these cleaning aids, it is more preferable to use toluene having low toxicity and having an appropriate boiling point.

  Diaminodiphenyl ether after distillation has a purity of 99% or more, but contains low-boiling monoamine and about 0.01% by mass of methyl mercaptoaniline as impurities. These impurities are removed and purified by the purification method of the present invention.

  If the temperature of the water washing operation, which is a purification method, is 75 ° C. or lower, the diaminodiphenyl ether does not melt, so that a washing effect cannot be obtained. Moreover, although operation is possible by pressurizing even at a high temperature of 100 ° C. or higher, it is not preferable from an economical viewpoint. Accordingly, it is desirable that the temperature be as low as possible above the temperature at which diaminodiphenyl ether melts. Considering the temperature uniformity of the devices, about 85 ° C. is a temperature at which operation is easy.

The water washing operation is performed by mixing and stirring water added with a cleaning aid and diaminodiphenyl ether at or above the melting temperature of diaminodiphenyl ether. Stirring is terminated when water and the cleaning aid solution of diaminodiphenyl ether are completely mixed, and stirring is stopped. After leaving, oil and water are separated and the water sinks, so the water is discarded. The oil phase diaminodiphenyl ether is analyzed to confirm the presence or absence of the above impurities, and if a large amount of impurities still remain, it is washed again with water. In this way, when the water washing is repeated to achieve a predetermined impurity concentration, it is judged that the water washing operation is completed, and the solvent as a washing aid and diaminodiphenyl ether are separated. The separation method can be evaporation or recrystallization, but is preferably a method of evaporating under reduced pressure near the boiling point of the solvent. The recrystallization method is not preferable because moisture is entrapped in the crystal lump, and it is necessary to take a method such as pulverization for drying.
When using toluene as a cleaning aid, it is preferable to evaporate under reduced pressure at about 110 ° C. This is because toluene and water form an azeotrope so that the diaminodiphenyl ether is more dried.

The amount of the cleaning aid used is 2 to 6 times, preferably 2.5 to 3.5 times the mass of diaminodiphenyl ether. If it is less than 2 times, since the specific gravity of the oil phase in which diaminodiphenyl ether is dissolved is high, separation from the aqueous phase becomes difficult. When it exceeds 6 times, it is not preferable from the point of economical efficiency.
The amount of water used for cleaning need not be determined, but may be determined according to the capacity of the apparatus. Usually, the amount of water is 0.1 to 2 times the mass of diaminodiphenyl ether.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
[Synthesis example]
[Synthesis of 4,4′-diaminodiphenyl ether]
In a 2000 ml flask equipped with a stirrer, 221 g (2 mol) of 4-aminophenol, 318 g (2 mol) of 4-chloronitrobenzene, 155 g (2.2 mol) of potassium carbonate as a condensing agent, and 539 g of dimethyl sulfoxide as a solvent And reacted at 140 ° C. for 5 hours.
Thereafter, 22 g of activated carbon and 11 g (0.2 mol) of iron (III) chloride were added thereto, hydrazine was added dropwise to react for 3 hours, and the completion of the reduction was confirmed by gas chromatography.
The reaction liquid was cooled and distilled to obtain 372 g of 4,4′-diaminodiphenyl ether having a purity of 99.6% by mass. This diaminodiphenyl ether had a methyl mercaptoaniline concentration of 0.01% by mass and a monoamine concentration of 0.25% by mass.

[Synthesis of 3,4'-diaminodiphenyl ether]
In the above synthesis, 4-aminophenol was replaced with 3-aminophenol, and the same operation was performed.
In this manner, 358 g of 3,4'-diaminodiphenyl ether having a purity of 99.8% by mass was obtained. This diaminodiphenyl ether had a methyl mercaptoaniline concentration of 0.01% by mass and a monoamine concentration of 0.12% by mass.

Example 1
3.5 g of water and 105 g of toluene were added to 35 g of the above 4,4′-diaminodiphenyl ether, and the mixture was stirred at 85 ° C., and then left to stand to discard the separated water. The methyl mercaptoaniline concentration in the oil phase at this time was 0.01% by mass or less on the basis of diaminodiphenyl ether, and the monoamine concentration was 0.14% by mass on the same basis. Accordingly, 3.5 g of water was further added to carry out a water washing operation. As a result, the monoamine concentration was 0.01% by mass or less based on diaminodiphenyl ether. This was dried under reduced pressure to obtain 32.6 g of 4,4′-diaminodiphenyl ether having a methyl mercaptoaniline concentration of 0.01% by mass or less and a monoamine concentration of 0.01% by mass.

Example 2
The same operation as in Example 1 was carried out instead of benzene. The washing was performed twice.
Example 3
The same operation as in Example 1 was carried out by replacing toluene with xylene. Washing with water was performed twice.
Example 4
The same operation as in Example 1 was performed except that the amount of toluene was 180 g. Washing with water was performed twice.
Example 5
The same operation as in Example 1 was performed except that the amount of water was 35 g. The washing was performed once.

Example 6
3.5 g of water and 105 g of toluene were added to 35 g of 3,4′-diaminodiphenyl ether, and the mixture was stirred at 85 ° C., and then left to stand to discard the separated water. The methyl mercaptoaniline concentration of the oil phase at this time was 0.01% by mass or less on the basis of diaminodiphenyl ether, and the monoamine concentration was 0.01% by mass or less on the same basis. This was dried under reduced pressure to obtain 33.6 g of 3,4'-diaminodiphenyl ether having a methyl mercaptoaniline concentration of 0.01% by mass or less and a monoamine concentration of 0.01% by mass or less.

Example 7
The same operation as in Example 6 was carried out by replacing toluene with benzene. One washing was performed.
Example 8
The same operation as in Example 6 was performed, except that toluene was replaced with xylene. The washing was performed once.
Example 9
The same operation as in Example 6 was performed except that the amount of toluene was 180 g. One washing was performed.

Comparative Example 1
The same operation as in Example 1 was performed except that the amount of toluene was 50 g. Although washing with water was performed, water and a toluene solution of diaminodiphenyl ether were insufficiently separated.
Comparative Example 2
The same operation as in Comparative Example 1 was conducted except that diaminodiphenyl ether was replaced with 3,4'-diaminodiphenyl ether. Although washing with water was performed, water and a toluene solution of diaminodiphenyl ether were insufficiently separated.

As mentioned above, the result of the Example and the comparative example was put together in Table 1-1 and 1-2.
According to the method of the present invention, methyl mercaptoaniline and diaminodiphenyl ethers having a low monoamine concentration can be obtained.

According to the present invention, it is a method for purifying diaminodiphenyl ether that can remove impurities by washing diaminodiphenyl ether after distillation with a cleaning aid and water. Since the obtained diaminodiphenyl ether has high purity, it can be used as a raw material for functional polyamide and polyimide.

Claims (3)

  In purifying diaminodiphenyl ether by washing with water, it is characterized in that benzene, toluene, xylene or a mixture thereof is added to the washing water as a washing aid in a mass ratio of 2 to 6 times that of diaminodiphenyl ether. And a method for purifying diaminodiphenyl ether.   The method for purifying diaminodiphenyl ether according to claim 1, wherein the diaminodiphenyl ether is 4,4'-diaminodiphenyl ether or 3,4'-diaminodiphenyl ether. The method for purifying diaminodiphenyl ether according to claim 1, wherein the diaminodiphenyl ether is diaminodiphenyl ether after distillation.