JPS60146850A - Purification of phenylenediamine - Google Patents

Abstract

PURPOSE:To obtain a phenylenediamine useful as a raw material for heat-resistant polyamide, etc. simply, efficiently in high purity, by bringing a liquid crude phenylenediamine into contact with an alkali metal hydroxide or an alkaline earth metal hydroxide. CONSTITUTION:A liquid crude phenylenediamine containing a small amount of impurities such as phenols, aminophenols, acid components, etc. is brought into contact with at least one of an alkali metal hydroxide or an alkaline earth metal hydroxide (preferably sodium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, etc.), or it is distilled and evaporated in the presence of at least one above-mentioned hydroxide, so that the phenylenediamine is purified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining highly purified phenylene diamines from crude phenylene diamines.

Phenyl diamines have long been used in large quantities in the rubber chemical industry and the dye/pigment industry, and recently meta- and para-phenylene diamines in particular have important industrial uses as raw materials for heat-resistant polyamides.

It is known that phenylenediamines are generally obtained by reduction of dinitrobenzene or nitroaniline or ammonolysis of aminophenol. To obtain the ortho, meta, and para isomers of phenylenediamine, there are a wide range of raw materials to choose from.

The phenylenediamines produced by such a method are obtained by removing the solvent, catalyst, unreacted raw materials, byproducts, etc. used in the reaction.

This removal method is usually carried out by distillation, but
Unreacted raw materials, by-products, and acid components are completely removed in this distillation operation.
It was not possible to completely eliminate them, and a small amount remained.

Meta- and para-phenylene diamines obtained by the above-mentioned methods usually contain a small amount of ortho-phenylene diamine. When it is necessary to remove this orthophenylenediamine, as shown in Japanese Patent Publication No. 57-7263, bisulfite of glucose and glyoxal are added with formamide and acid as shown in Japanese Patent Publication No. 57-7624. By adopting a method of distillation after heat treatment, I can obtain
In this method, a small amount of the added acid components and the like are mixed into the obtained meta- and para-phenylenediamine, and the remaining unreacted raw materials and by-products mentioned above are not removed. In particular, in order to obtain high-purity phenylene diamines, such as raw materials for heat-resistant polyamides, it is necessary to repeat high-level rectification or crystallization, which has the disadvantage of high purification costs for industrial implementation. are doing.

The present inventors have conducted intensive studies on a method for overcoming the shortcomings of these conventional methods and obtaining phenylene diamines of higher purity than crude phenylene diamines in a simpler and more efficient manner. The present invention was accomplished by discovering that highly pure phenylenediamines can be obtained by contact treatment with an alkali metal or alkaline earth metal hydroxide.

That is, the present invention involves distilling or evaporating liquid crude phenylene diamines after contact treatment with at least one hydroxide of an alkali metal or alkaline earth metal or in the presence of at least one hydroxide. This is a method for purifying phenylenediamines.

The crude phenylene diamines used in the present invention refer to phenylene diamines synthesized by the reduction method of dinitrobenzene, nitroaniline, and aminoazobenzene, or the ammonolysis method of aminophenol, and from which solvents, catalysts, etc. are removed by ordinary distillation operations. It is a phenylene diamine that contains small amounts of impurities such as phenols, aminophenols, and acid components, such as phenylene diamines obtained by adding an acid component for isomer separation.

The hydroxides of alkali metals or alkaline earth metals used in the present invention include readily available commercially available sodium hydroxide, magnesium hydroxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, and hydroxide. Barium and the like are preferred, and can be used in the form of an aqueous solution or as a solid. It is preferable to use hydroxides of in situ metals or alkaline earth metals in the form of aqueous solutions. The required amount of alkali metal or alkaline earth metal hydroxide varies depending on the content of acid, phenol, or aminophenol in the crude phenylenediamine, but it is usually equivalent to the acid, aminophenol, or phenol. It is sufficient if the amount is not less than 20% by weight relative to the crude phenylenediamine.

If the amount of alkali metal or alkaline earth metal hydroxide added is less than the amount indicated in the present invention, not only will a sufficient effect not be obtained, but the phenylenediamine obtained as a product may be colored. It has the disadvantage of being

On the other hand, if it is added in a large amount exceeding the amount shown in the present invention, the purity and coloring prevention effect are sufficient, but the amount of alkali metal or alkaline earth metal hydroxide used increases, making it uneconomical. In addition, the viscosity of the high-boiling substances remaining at the bottom of the rectification column or evaporator shown in the treatment method described later becomes abnormally high, making extraction and other handling difficult, which is undesirable.

The method of contact treatment of crude phenylene diamines with an alkali metal or alkaline earth metal hydroxide involves first making the crude phenylene diamines liquid at a temperature above the melting point and maintaining this state before bringing the hydroxide into contact with the crude phenylene diamines. . When the hydroxide is an aqueous solution, it is brought into contact by a known liquid-liquid contact method, separated into two phases, and the phenylenediamine layer is taken out and subjected to subsequent distillation or evaporation. When the hydroxide is a solid, a known solid-liquid contact method may be used, for example, a liquid crude phenylenediamine and the hydroxide are placed in a container equipped with a stirrer, stirred and mixed, and then a known solid-liquid contact method is used. There is a method in which a liquid phase is taken out by a liquid separation method, and a method in which the crude phenylenediamine is passed through a tower filled with the solid hydroxide and brought into contact with it to be taken out.

The contact time between the crude phenylene diamine and the alkali metal or alkaline earth metal hydroxide is not particularly limited, but usually several minutes to about 60 minutes is sufficient. The contact treatment temperature may be at least the melting point at which the crude phenylenediamine becomes liquid. If the temperature is too high, it will decompose, so the upper limit is 2.
The temperature is about 70°C. For distillation or evaporation in the presence of an alkali metal, metal or alkaline earth metal hydroxide, an aqueous solution or granular solid of the hydroxide is mixed with liquid crude phenylenediamine and the mixture is directly transferred to a distillation apparatus or evaporation apparatus. Just supply it.

Alternatively, if the hydroxide is previously present at the bottom of the distillation device or evaporation device, the crude phenylenediamine and the hydroxide may be separately supplied to the bottom of the device.

The equipment for distillation and evaporation used in the present invention does not need to be special. The choice between distillation and evaporation depends on the purity required for the purified phenylenediamine obtained. Needless to say, distillation is used when higher purity is required.

The conditions for distilling or evaporating crude phenylenediamines after treatment with or in the presence of an alkali metal or alkaline earth metal hydroxide may be either continuous or batchwise. The temperature conditions need to be about 270°C or lower. If the temperature is higher than this, thermal decomposition of phenylenediamines occurs, which not only reduces the amount recovered, but also causes coloration and an increase in impurities, resulting in a decrease in purity, making the addition of hydroxide meaningless.

The pressure is the vapor pressure corresponding to the temperature, about 200 am H
g or less.

By the method of the present invention, phenols, aminophenols, acids, acids, and acids added for isomer separation, which are generated during the production of phenylenediamines and remain unreacted, are removed, resulting in purification with a purity of 99% by weight or more. Phenylenediamines are obtained.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited in any way by these Examples. Note that the percentages in the examples are by weight. The analysis was also carried out by gas chromatography.

Example 1 Aniline 40.5 was added to a 500 ml reactor equipped with a stirrer, thermometer, condenser and NOx gas inlet.
f, 29.61 g of sulfuric acid, and 286.5 g of water were charged, cooled to -3 to 3°C with sufficient stirring, and NOx gas, in which nitrogen monoxide and oxygen had been sufficiently mixed together as a diazotizing agent, was added to the
After cooling to 0°C, a theoretical amount of NOx gas for reaction was blown under atmospheric pressure to complete the diazotization reaction. 50O of aniline
Add the solution after the completion of the diazotization reaction to a round bottom flask equipped with a stirrer, a thermometer, and a condenser, and heat at 35°C for 30 minutes.
After sufficient stirring for several minutes, the reaction temperature was raised to 75°C, and after reacting for 6 hours, 729 g of 25% female water was added to perform a sulfuric acid neutralization reaction. After the neutralization reaction was completed, static liquid separation was performed and the aqueous layer was separated to obtain aniline 1tlJ 560 f/. An autoclave was charged with 560 f of aniline layer and 5.2 f of Raney nickel, and a reduction reaction was carried out under the conditions of a reaction temperature of 100 to 110°C and a hydrogen pressure of 9 Kf 10n2G.

Hydrogen absorption was completed in about 3 hours, at which point aminoazobenzene had completely disappeared. After the reduction reaction is completed, the catalyst is removed by filtration, distilled under reduced pressure to separate and collect low-boiling fractions such as aniline, and dimethylformamide is added in an amount equivalent to 2 times the mole of orthophenylenediamine and 1.1 times the amount of orthophenylenediamine. To 30 y of crude para-phenylene diamine obtained by adding mol equivalent of acetic acid to 32 g of crude para-phenylene diamine, powdered sodium hydroxide was added to 30 g of crude para-phenylene diamine.
After adding 7f and heating at a reaction temperature of 160°C for 30 minutes, simple distillation was performed under reduced pressure of 7 to 121111+- to obtain 289 para-phenylene diamines with a purity of 99.9% as a distillate.

Comparative Example 1 Crude para-phenylenediamine with a purity of 98.5% obtained in the same manner as in Example 1 was treated in exactly the same manner except that sodium hydroxide was not added. The purity of the resulting para-phenylenediamine fraction was 98.8%.

Example 2 0.89 g of potassium hydroxide was added to 35 g of crude para-phenylene diamine with a purity of 98.7 obtained by the same method as in Example 1.
was added and heat treated at a reaction temperature of 160°C for 30 minutes.
Simple distillation was performed under reduced pressure of ~12 mHg to obtain 32y of para-phenylenediamine with a purity of 99.9% as a distillate.

Example 3 1.4 g of 48% sodium hydroxide aqueous solution was added to crude para-phenylenediamine 359 with a purity of 98.7% obtained in the same manner as in Example 1, and evaporated under reduced pressure of 7 to 12%. 31F with a purity of 99.7% was obtained as a condensate.

Example 4 Calcium hydroxide 1.2 was added to 351 crude paraphenylenediamine with a purity of 98.6% obtained by the same method as in Example 1.
After heat treatment at a reaction temperature of 160° C. for 30 minutes, simple distillation was performed under reduced pressure of 7 to 12 mHg to obtain 321 para-phenylenediamine with a purity of 99.7% as a distillate.

Example 5 Crude meta-dinitrobenzene containing 1.2 units of ortho-dinitrobenzene 42. Of and ethanol 300- and 2.6 g of commercially available 5-T Pd-activated carbon supported catalyst (manufactured by Nippon Engelhard Co., Ltd.) as a catalyst were placed in an autoclave.
The reduction reaction was carried out under the conditions of a reaction temperature of 100 to 110°C and a hydrogen pressure of 9/2G. Hydrogen absorption was completed in about 3 hours, at which point dinitrobenzene had completely disappeared. After the completion of the hydrogen reduction reaction, the catalyst was removed by filtration, and low-boiling fractions such as water and ethanol were separated and collected by vacuum distillation, and dimethylformamide and orthophenylenediamine sauce were added in an amount equivalent to twice the mole of orthophenylenediamine. 1
．． 160 to 1 at normal pressure after adding twice the mole equivalent of acetic acid.
Heat treatment was performed at 65°C for 40 minutes. After that, simple distillation was carried out under reduced pressure of 10 to 15 m to obtain 21.8 N'4 of crude metaphenylenediamine with a purity of 98.2%. 0.259 ml of powdered sodium hydroxide was added to 20 f of crude metaphenylene diamine, and after heat treatment at a reaction temperature of 150°C for 30 minutes,
Simple distillation was carried out under reduced pressure using 11g of water, and the distillate had a purity of 9.
9.8% of metaphenylene diamine was obtained.

Comparative Example 2 20 g of crude meta-phenylenediamine with a purity of 98.3% obtained by the same method as in Example 5 was treated in the same manner except that sodium hydroxide was not added.The resulting meta-phenylenediamine The purity of the fraction was 98.6%.

Example 6 Crude para-phenylenediamine 175F with a purity of 98.7% obtained by the same method as in Example 1 was charged into a 300-liter reactor equipped with a stirrer and heated from the outside to completely dissolve it, followed by flaky water. 14f of sodium oxide was added. contact temperature
After processing at 180-165°C for 30 minutes with stirring,
The solution from which flaky sodium hydroxide was removed through a heated glass filter was distilled under reduced pressure in 6 to 10 ml to obtain 164 g of para-phenylene diamine with a purity of 99.8%.

Example 7 250 f of pure [98.8% crude para-phenylenediamine containing 0.9% para-aminophenol and 0.2% phenol] was placed in a column filled with 30 y of pellet-shaped sodium hydroxide having a diameter of about 5 wm at a temperature of 170 y. ~175℃, contact time 40 minutes, and the resulting liquid was heated at 6~10mH.
Evaporation was carried out under reduced pressure to obtain 228 g of paraphenylenediamine with a purity of 99.9% as a condensate.

Claims (1)

[Claims] (1) Contact treatment of liquid crude phenylene diamines with at least one hydroxide of an alkali metal or alkaline earth metal followed by distillation or evaporation, or distillation in the presence of at least one hydroxide. or a method for purifying phenylenediamines, characterized by evaporation.