JPH0446261B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for removing orthophenylenediamine from phenylenediamines. More specifically, orthophenylene is produced by adding dimethylformamide and an acid or a bisulfite adduct of dimethylformamide to phenylene diamine containing orthophenylene diamine, and causing orthophenylene diamine and the additive to react with heat. The present invention relates to a method for removing ortho-phenylene diamine from phenylene diamines, which comprises converting the diamine into a high-boiling substance and then distilling it. 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. Normally, about 1 to 10% by weight of orthophenylenediamine is present as an impurity. 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 phenylenediamines in a normal pressure system or a reduced pressure system, and it is difficult to perform industrial implementation. In this case, there are disadvantages in that it is essential 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. The present inventors have overcome the drawbacks of these conventional methods,
As a result of extensive research into a simpler and more efficient method to obtain meta- and para-phenylene diamines containing very little to no ortho-phenylene diamine, we discovered that ortho-phenylene diamine was reacted with a specific compound. The present invention was achieved by discovering that highly pure phenylenediamines can be obtained by distilling the phenylenediamines. That is, the present invention involves heat-treating phenylene diamines containing ortho-phenylene diamine at about 100 to 270°C in the presence of dimethylformamide and an acid or a bisulfite adduct of dimethylformamide, and then distilling the mixture. The present invention provides a method for efficiently removing orthophenylenediamine from phenylenediamines containing orthophenylenediamine by distillation at a temperature of 100 to 270°C. In carrying out the method of the present invention, the phenylene diamines containing orthophenylene diamine used as the treatment target are not particularly limited, but are usually metaphenylene diamine produced by reduction of metadinitrobenzene or para-aminoazobenzene. Preferred are paraphenylene diamines produced by reduction and ammonolysis of chloroaniline with ammonia, reduction of nitroaniline, amination of hydroxyl groups of aminophenol with ammonia, ammonolysis of dichlorobenzene with ammonia, and the like. Generally, the phenylene diamines produced by these methods contain about 10% by weight or less of the ortho form. In carrying out the process of the present invention, dimethylformamide and an acid or a bisulfite adduct of dimethylformamide are added to the phenylene diamines to react with the ortho-phenylene diamine present in the phenylene diamines. Acids used in combination with dimethylformamide include sulfuric acid, hydrochloric acid, benzenesulfonic acid, toluenesulfonic acid, acetic acid, benzoic acid, and the like. The amount of dimethylformamide added is determined by the content of orthophenylenediamine in the phenylenediamines, but the molar ratio of dimethylformamide to the orthophenylenediamine normally contained is 1 or more, preferably 1.05 to 1.05. 4
Used within the range of When the molar ratio of dimethylformamide to orthophenylenediamine is less than 1, the removal rate of orthophenylenediamine decreases, and on the other hand, when it is in excess of 4, unreacted dimethylformamide must be treated, which is industrially undesirable. The amount of acid added is generally 0.1 or more, preferably 0.3 to 2 in molar ratio to orthophenylene diamine present in the phenylene diamine. However, if only dimethylformamide is added to a phenylene diamine containing ortho-phenylene diamine in the absence of an acid and then heat-treated, the ortho-phenylene diamine cannot be sufficiently removed. Furthermore, examples of bisulfites used in the present invention include sodium salts and ammonium salts of sulfite. Bisulfite adducts of dimethylformamide can be easily prepared by mixing dimethylformamide and bisulfite, or by adding dimethylformamide and bisulfite separately to phenylenediamines. You can get the same effect no matter what. The amount of the bisulfite adduct of dimethylformamide to be added is preferably 1 or more in molar ratio to orthophenylenediamine normally contained.
It is desirable that it be around 1.05 to 4. When the molar ratio of bisulfite adduct of dimethylformamide 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 dimethylformamide is removed. It is not desirable industrially because it requires treatment. In carrying out the method of the present invention, a mixture of phenylene diamines containing ortho-phenylene diamine and the above additive is reacted with the additive to convert the ortho-phenylene diamine into a high boiling point product. heated for. The temperature when dimethylformamide and an acid or a bisulfite adduct of dimethylformamide are added to phenylene diamines and then subjected to heat treatment or distillation under heat treatment conditions varies depending on the amount and type of additives added, but generally If the temperature exceeds 270°C, the decomposition and tar formation of phenylene diamines will be accelerated, and the yield of recovered meta- and para-phenylene diamines will be significantly reduced.
If the temperature is lower than 100℃, the removal rate of orthophenylenediamine will be lower, so it is usually 100 to 270℃.
Processed for a temperature range of ℃. The heat treatment time is not particularly limited, but is usually several seconds or more.
About 60 minutes is sufficient. There is no particular problem even if the heat treatment time is made longer. The phenylene diamines heat-treated as described above are then subjected to distillation treatment to separate and recover the desired phenylene diamines that do not contain the ortho form. The distillation temperature may be arbitrarily selected in relation to the operating pressure. In the above description, the case where additives are added to phenylene diamines, heat treated, and then distilled is 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 is approximately
Conducted at 100-270°C. The reason is the same as the heat treatment conditions. Thus, the content of ortho isomers in the phenylenediamine fraction obtained by distillation is 0.5% by weight or less,
Desirably, the content 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. In addition, the percentages in the examples are % by weight.
It is. Example 1 3.0% orthophenylenediamine and 2.4%
paraphenylenediamine containing aniline
Pour 330g into a 500c.c. round bottom flask, introduce nitrogen gas from the capillary, and raise the pot temperature to 165-180.
After complete dissolution at
2.9 times the molar equivalent) and 7.5 g of 36% hydrochloric acid were sequentially added to the pot liquid, and total reflux was carried out for 30 minutes. Then 30～
Simple distillation was carried out under a reduced pressure of 60 mmHg at a pot temperature of 160 to 180°C, and after removing 33 g of the initial distillate containing aniline, water, dimethylformamide, etc., 275 g of a distillate containing paraphenylene diamine 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 no hydrochloric acid was added. As a result, the concentration of orthophenylenediamine in the paraphenylenediamine fraction obtained was 2.8%. Example 2 Paraphenylenediamine with the same composition as Example 1
After charging 300 g into the same equipment used in Example 1 and completely dissolving it in the same manner, 16.0 g of 50% ammonium bisulfite aqueous solution and 18.3 g of dimethylformamide (based on orthophenylenediamine) were added.
A mixed solution of 3.0 times the molar equivalent) was added to the pot liquid, and total reflux was carried out for 60 minutes. Then 30~60mm
Simple distillation is carried out under reduced pressure of Hg at a pot temperature of 160 to 180℃.
After removing 38 g of the first fraction containing aniline, water, dimethylformamide, etc., 236 g of a fraction containing paraphenylenediamine as a main component was obtained. The concentration of orthophenylenediamine in the paraphenylenediamine fraction was 0.18%. Examples 3 to 7 Paraphenylenediamine with the same composition as Example 1
After 350 g was charged into the same apparatus used in Example 1 and completely dissolved in the same manner, dimethylformamide and acid were added in the proportions shown in Table 1, and after 40 minutes of total reflux, the temperature was 30-60 mmHg. Simple distillation was carried out under reduced pressure at a pot temperature of 160 to 180°C, and after removing 35 to 40 g of the initial distillate, a fraction containing paraphenylenediamine as a main component was obtained. The concentration of orthophenylenediamine in the paraphenylenediamine fraction was analyzed. The results are shown in Table 1.

[Table] Example 8 300g of paraphenylenediamine containing 4.5% orthophenylenediamine and 2.0% metaphenylenediamine was placed in a 500c.c. round bottom flask, and while nitrogen gas was introduced from the capillary, the temperature of the flask was adjusted.
After completely dissolving at 165-180℃, add 6.3% of acetic acid.
A mixed solution of g and 20.9 g of dimethylformamide (equivalent to 2.3 times the mole relative to orthophenylenediamine) was added to the pot liquid, and total reflux was carried out for 20 minutes. Distillation was then carried out at a reflux ratio of 5 under reduced pressure of 30 to 60 mmHg, and after removing 18 g of the first fraction containing dimethylformamide etc., 245 g of a fraction containing paraphenylenediamine as a main component was obtained. The concentration of orthophenylenediamine in the paraphenylenediamine fraction is 0.03%, and the concentration of metaphenylenediamine is 1.9.
It was %. Example 9 A 500 c.c. round bottom flask was charged with 315 g of metaphenylene diamine containing 3.1% orthophenylene diamine and 6.8% paraphenylene diamine.
While introducing nitrogen gas from the capillary, the pot temperature was increased.
After completely dissolving at 160 to 190°C, a solution of 14.7 g of dimethylformamide (equivalent to 2.2 times the mole relative to orthophenylenediamine) and 12.6 g of para-toluenesulfonic acid was added to the pot liquid. Total reflux was performed for 45 minutes. Next, simple distillation was carried out under reduced pressure of 30 to 45 mmHg to remove 32 g of the first distillate containing dimethylformamide and the like, yielding 248 g of a fraction containing metaphenylenediamine as a main component. The concentration of orthophenylenediamine in the metaphenylenediamine fraction was 0.02%, and the concentration of paraphenylenediamine was 6.2%.

Claims (1)

[Claims] 1 A phenylene diamine containing orthophenylene diamine is heat-treated at about 100 to 270°C in the presence of dimethylformamide and an acid or a bisulfite adduct of dimethylformamide, and then distilled, or about 100 to 270°C A method for removing orthophenylenediamine from phenylenediamines, the method comprising distillation at a temperature of .