JPH0446259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing orthophenylenediamine diamine from aromatic diamines. More specifically, a bisulfite adduct of formamide is added to an aromatic diamine containing orthophenylenediamine, and the orthophenylenediamine and the additive are heated to react, thereby converting the orthophenylenediamine into a high-boiling substance. The present invention relates to a method for removing orthophenylenediamine from aromatic diamines, which comprises distilling the aromatic diamines.

Meta- and paraphenylenediamines have long been used in large quantities in the rubber chemical industry and dye/pigment industry, and have recently found important industrial use as raw materials for heat-resistant polyamides.
Usually, meta-phenylene diamine is produced by reduction of metadinitrobenzene, and para-phenylene diamine is produced by reduction of para-nitroaniline or para-aminoazobenzene. Usually orthophenylenediamine is about 1
Exists as an impurity at ~10% by weight.

Conventionally, as a method for removing orthophenylene diamine from meta- and para-phenylene diamines containing such ortho-phenylene diamine, for example, glucose or glyoxal or its polymers have been used as disclosed in Japanese Patent Publication No. 7623/1983. A method of separating orthoaromatic diamines by adding a sulfite adduct and distilling, and a method of adding formamide or formamide and an acid and distilling after heat treatment, as shown in Japanese Patent Publication No. 57-7624, Methods for separating orthoaromatic diamines are known.

However, in these methods, it is difficult to directly add glyoxal and formamide during distillation because the boiling point of glyoxal and formamide is lower than the melting point of aromatic diamines in a normal pressure system or a reduced pressure system. In this case, there are disadvantages in that it is necessary to carry out pretreatment of the pressurized system and in that a large amount of reagent must be used in order to obtain a sufficient effect.

In addition, when adding an acid together with a reagent, it exhibits a remarkable effect compared to not adding it, but since the acid reacts with aromatic diamines and produces diamine salts, the aromatic diamines that are the target of recovery are Not only is there a disadvantage that the recovery rate is lowered, but in the industrial production method, the acid used causes a problem of corrosion of the equipment, and it is necessary to use expensive equipment.

The present inventors have endeavored to overcome the shortcomings of these conventional methods and to develop a method for obtaining meta- and para-phenylene diamines that contain extremely little to no ortho-phenylene diamine in a simpler and more efficient manner. As a result of repeated studies, the inventors discovered that highly pure aromatic diamines can be obtained when orthophenylene diamine is reacted with a specific compound and distilled, and the present invention has been achieved. That is, the present invention involves heating aromatic diamines containing orthophenylenediamine in the presence of a bisulfite adduct of formamide at about 100 to 270°C and then distilling them, or distilling them at a temperature of about 100 to 270°C. An object of the present invention is to provide a method for efficiently removing orthophenylenediamine from aromatic diamines containing orthophenylenediamine by distillation.

In carrying out the method of the present invention, the aromatic diamines containing orthophenylenediamine used as the treatment target are not particularly limited;
It is usually produced by reduction of metaphenylenediamine or para-aminoazobenzene produced by reduction of metadinitrobenzene, ammonolysis of chloroaniline with ammonia and reduction of nitroaniline, amination of hydroxyl group of aminophenol with ammonia, and ammonolysis of chlorobenzene with ammonia. Paraphenylene diamine and the like are preferably used.

Generally, the aromatic diamines produced by these methods contain about 10% by weight or less of the ortho isomer.

In carrying out the process of the invention, a bisulfite adduct of formamide is added to the aromatic diamines and reacted with the orthophenylene diamine present in the aromatic diamines.

Examples of bisulfites used in the present invention include sodium salts and ammonium salts of sulfite.

Bisulfite adducts of formamide can be easily prepared by mixing formamide and bisulfite, or by adding formamide and bisulfite separately to aromatic diamines. You can get the effect.

The amount of the bisulfite adduct of formamide to be added is desirably 1 or more, preferably about 1.05 to 4 in molar ratio to the orthophenylene diamine normally contained.

When the molar ratio of bisulfite adduct of formamide to orthophenylene diamine is less than 1, the removal rate of orthophenylene diamine decreases, while when it is in excess of 4, unreacted bisulfite adduct of formamide is removed. It is not desirable industrially because it requires treatment.

In the present invention, bisulfites of formamide can obtain effects that are not obtained at all or hardly when formamide and acid are added.
It was also revealed that the method of the present invention is more effective in removing orthophenylenediamine than when only formamide is added.
It has become clear that this method is industrially more desirable than the case where an acid is added as shown in the publication.

In carrying out the method of the present invention, a mixture of aromatic diamines containing orthophenylene diamine and the above additive is reacted with the additive to convert orthophenylene diamine into a high boiling point product. heated for. The temperature when adding bisulfite adducts of formamide to aromatic diamines and distilling them under heat treatment or heat treatment conditions varies depending on the amount and type of additives added, but generally the temperature is 270°C or higher. If the temperature is lower than 100°C, the decomposition and tar formation of phenylene diamines will be promoted and the yield of meta- and para-phenylene diamines will be significantly reduced. Since the temperature is low, it is usually processed at a temperature range of 100 to 270°C.

The heat treatment time is not particularly limited, but usually several seconds to about 60 minutes is sufficient. There is no particular problem even if the heat treatment time is made longer.

The aromatic diamines heat-treated as described above are then subjected to distillation treatment to separate and recover the target phenylene diamine that does not contain the ortho form.

The distillation temperature may be arbitrarily selected in relation to the operating pressure.

In the above explanation, the case where additives are added to aromatic diamines and distilled after heat treatment has been explained, but the method of the present invention can also carry out the heat treatment and distillation at the same time, which is a particularly preferred embodiment. . For such embodiments, the distillation temperature is approximately
Conducted at 100-270°C. The reason is the same as the heat treatment conditions.

Thus, the content of the ortho isomer in the phenylenediamine fraction obtained by distillation is 0.1% by weight or less,
If desired, it can be reduced to 0.01% by weight or less, and its industrial value is extremely high.

According to the method of the present invention as detailed above, it is possible to obtain meta- or para-phenylene diamine containing very little to no ortho-phenylene diamine with a small amount of additives compared to conventionally known methods. The industrial benefits of being able to do so are demonstrated.

Furthermore, the method of the present invention is easy to implement in that it does not require a pressurized reaction unlike conventional methods.

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.

Example 1 3.9% orthophenylenediamine and 2.5%
paraphenylenediamine containing aniline
Pour 310g into a 500c.c. round bottom flask, and while introducing nitrogen gas from the capillary, raise the kettle temperature to 165-170℃.
After completely dissolving the solution, add 39.9 g of 50% ammonium bisulfite aqueous solution (1.8 times the molar equivalent to orthophenylenediamine) and 9.1 g of formamide.
g (1.8 times the molar equivalent to orthophenylenediamine) was added to the pot solution, and heat-treated at 170° C. for 40 minutes at normal pressure. Next, the pot temperature
Simple distillation was performed at 165-180°C under reduced pressure of 30-60 mmHg to remove 35 g of the first distillate containing aniline, water, formamide, etc., and then 249 g of a fraction containing paraphenylenediamine as the main component was obtained. .

The concentration of orthophenylenediamine in the paraphenylenediamine fraction was 0.01%.

On the other hand, for comparison, the same treatment as above was carried out except that the 50% ammonium bisulfite aqueous solution was not added. The concentration of orthophenylenediamine in the resulting paraphenylenediamine fraction was 0.89%.

For comparison, the same procedure as above was carried out except that a 50% aqueous ammonium bisulfite solution was added and formamide was not added. The concentration of orthophenylenediamine in the resulting paraphenylenediamine fraction was 1.37%.

Example 2 305g of paraphenylenediamine containing 4.2% orthophenylenediamine was charged into the same equipment as used in Example 1, completely dissolved in the same manner, and then sulfur dioxide gas was absorbed into 20% aqueous ammonia. ammonium bisulfite 53.6% and ammonium sulfite 6.2% and ammonium sulfate
Immediately after adding 46.8 g of a 3.6% mixed aqueous solution to the pot solution, 8.8 g of formamide was added, and total reflux was carried out for 30 minutes. Then, under reduced pressure of 30-60mmHg, the pot temperature was 165-
Simple distillation was carried out at 180°C to remove 25 g of the first fraction containing water, formamide, etc., and 258 g of a fraction containing paraphenylenediamine as the main component was obtained. The concentration of orthophenylenediamine in the paraphenylenediamine fraction was 0.09%.

Example 3 Paraphenylenediamine with the same composition as Example 1
After charging 350 g into the same equipment used in Example 1 and completely dissolving it in the same manner, a mixed solution of 81.8 g of 36% sodium bisulfite aqueous solution and 12.4 g of formamide was added to the pot liquid, and the total reflux was brought to a boil. It was conducted for 40 minutes. Then, under reduced pressure of 30 to 60 mmHg, the pot temperature was 165
After performing simple distillation at ~180℃ and removing 48g of the first distillate,
Distillate 286 whose main component is paraphenylenediamine
I got g. The concentration of orthophenylenediamine in the paraphenylenediamine fraction was 0.04%.

Example 4 4.3% orthophenylenediamine and 13.2
% paraphenylene diamine was charged into a 500 c.c. round bottom flask, and after completely dissolving it at a pot temperature of 155 to 160 °C while introducing nitrogen gas from the capillary, A mixed solution of 46.4 g of % ammonium bisulfite aqueous solution and 9.2 g of formamide was added to the pot liquid,
Total reflux was performed for 30 minutes. Next, set the pot temperature to 160-185.
C. and under reduced pressure of 25 to 50 mmHg to remove 38 g of the initial distillate, to obtain 272 g of a fraction containing metaphenylenediamine as a main component. The concentration of orthophenylenediamine in the metaphenylenediamine fraction is 0.07%, and the concentration of paraphenylenediamine is 13.9.
It was %.

On the other hand, for comparison, treatment was carried out in exactly the same manner as above except that the 50% aqueous ammonium bisulfite solution was not added. The concentration of orthophenylenediamine in the resulting metaphenylenediamine fraction was 1.23%, and the concentration of paraphenylenediamine was
It was 13.5%.

Claims (1)

[Claims] 1. Aromatic diamines containing orthophenylenediamine are heat treated at about 100 to 270°C in the presence of a bisulfite adduct of formamide and then distilled, or distilled at a temperature of about 100 to 270°C. A method for removing orthophenylene diamine from aromatic diamines, characterized by: