JPH0446260B2 - - 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 furfural or a bisulfite additive of furfural and acid or furfural to phenylene diamines containing orthophenylene diamine, and causing orthophenylene diamine and the additive to react with heat. This 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. Usually 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 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. After repeated studies, we reacted orthophenylenediamine with a specific compound,
The present invention was achieved by discovering that highly pure phenylene diamines can be obtained by distillation. That is, the present invention involves heat-treating phenylene diamines containing ortho-phenylene diamine at about 100 to 270°C in the presence of furfural or furfural and an acid or a bisulfite adduct of furfural, and then distilling the mixture. It is an object of the present invention to provide 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, furfural or a bisulfite adduct of furfural and acid or furfural is added to the phenylene diamines and reacted with the orthophenylene diamine present in the phenylene diamines. Acids used in combination with furfural include sulfuric acid, hydrochloric acid, benzenesulfonic acid, toluenesulfonic acid, acetic acid, benzoic acid, and the like. The amount of furfural added is determined by the content of orthophenylenediamine in the phenylenediamines, but the molar ratio of furfural to the orthophenylenediamine normally contained is 1 or more, preferably 1.05 to 4. Used in range. When the molar ratio of furfural 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 furfural must be treated, which is industrially undesirable. When carrying out the method of the present invention, orthophenylenediamine can be removed by adding only furfural to phenylenediamines containing orthophenylenediamine and heat-treating, but addition of furfural and acid or bisulfite of furfural If carried out in the presence of a substance, the reaction between orthophenylenediamine and furfural will be significantly improved, and the target orthophenylenediamine can be removed by heat treatment at a lower temperature and in a shorter time, making it an industrially excellent product. It's a method. 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. Furthermore, examples of bisulfites used in the present invention include sodium salts and ammonium salts of sulfite. Bisulfite adducts of furfural can be easily produced by mixing furfural and bisulfite, or by adding furfural and bisulfite separately to phenylene diamines. You can get the effect. The amount of the bisulfite adduct of furfural 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 the bisulfite adduct of furfural to ortho-phenylene diamine is less than 1, the removal rate of ortho-phenylene diamine decreases, while when it is in excess of 4, the removal rate of the bisulfite adduct of furfural that has not reacted is removed. This is not desirable industrially. 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 furfural and an acid or a bisulfite adduct of furfural are added to phenylene diamines and subjected to heat treatment or distillation under heat treatment conditions varies depending on the amount and type of additives added, but generally the temperature is If the temperature is higher than 270℃, the decomposition and tar formation of phenylene diamines will be promoted, and the yield of meta- and para-phenylenediamines will be significantly reduced. Since the removal rate of nylene diamine is low, the treatment is usually carried out at a temperature range of 100 to 270°C. 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 perform the heat treatment and distillation at the same time, which is a particularly preferred embodiment. For such embodiments, the distillation is about 100
Performed at ~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 1.0% by weight or less,
Desirably, the content can be reduced to 0.05% 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 or 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 2.8% orthophenylenediamine and 2.3%
paraphenylenediamine containing aniline
Pour 307g into a 500c.c. round bottom flask, and while introducing nitrogen gas from the capillary, raise the pot temperature to 165-180.
After completely dissolving at °C, 19.1 g of furfural
(2.5 times molar equivalent to orthophenylenediamine) and 50% ammonium bisulfite aqueous solution
14.1 g were added to the pot solution in order, and total reflux was carried out for 30 minutes. Then reduce the pressure to 30-60mmHg and reduce the pot temperature to 160-
Simple distillation was performed at 180°C to remove 31 g of the first distillate containing aniline, water, furfural, etc., and then 252 g of a distillate containing paraphenylenediamine as the main component was obtained.
The concentration of orthophenylenediamine in the paraphenylenediamine fraction was 0.05%. On the other hand, for comparison, treatment was carried out in exactly the same manner as above except that furfural and 50% aqueous ammonium bisulfite solution were not added. the result,
The concentration of orthophenylenediamine in the paraphenylenediamine fraction obtained was 2.4%. 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, 29.8 g of furfural (relative to orthophenylene diamine) was added.
4.0 times the molar equivalent) was added to the pot solution, and total reflux was carried out for 90 minutes. Next, simple distillation is performed under reduced pressure of 30 to 60 mmHg to obtain 24 g of the first distillate containing aniline, furfural, etc., followed by the paraphenylenediamine fraction.
Obtained 258g. The concentration of orthophenylenediamine in the paraphenylenediamine fraction was 0.45%. Example 3 28.7 g of furfural (relative to ortho-phenylene diamine) to 320 g of para-phenylene diamine containing 17.8% meta-phenylene diamine in a 500 c.c. round bottom flask.
2.2 times molar equivalent) and ammonium sulfite 9%
After adding 35.6 g of an aqueous solution containing 34% ammonium hydrogen sulfite, the mixture was heated under reduced pressure while introducing nitrogen gas from the capillary, and after the whole was completely dissolved, the pot temperature was 160-190°C and 30-45 mmHg. Simple distillation was performed under reduced pressure to remove 38 g of the first distillate containing water, furfural, etc., and then 275 g of a fraction containing paraphenylenediamine as the main component was obtained. The concentration of orthophenylenediamine in the paraphenylenediamine fraction was 0.9%, and the concentration of metaphenylenediamine was 16.3%. Examples 4 to 9 Paraphenylene diamine with the same composition as Example 1
After charging 350 g into the same equipment used in Example 1 and dissolving it in the same manner, furfural and acid were added in the proportions shown in Table 1, and after 40 minutes of total reflux, the temperature was reduced to 160°C under vacuum at 30 to 60 mmHg. Simple distillation was carried out at ~180°C, and after removing 35 to 40 g of the initial fraction, a fraction containing paraphenylenediamine as the main component was obtained. Table 1 shows the results of analyzing the concentration of orthophenylenediamine in the paraphenylenediamine fraction. 【table】

Claims (1)

[Claims] 1. Aromatic diamines containing orthophenylenediamine are heat-treated at about 100 to 270°C in the presence of furfural or furfural and an acid or a bisulfite adduct of furfural, and then distilled, or about 100 to 270°C A method for removing orthophenylenediamine from phenylenediamines, which comprises distilling at a temperature of .