A production process of antioxidant o-phenylenediamine

Abstract

The invention discloses a kind of antioxidant o-phenylenediamine production process, belongs to the technical field of o-phenylenediamine preparation, comprises the following steps: add skeleton nickel catalyst, o-nitroaniline, methanol to autoclave, pass into the air of hydrogen replacement reaction system, stir and heat up, pass into hydrogen, close air inlet valve to react, cool, discharge, steam out solvent methanol, obtain crude o-phenylenediamine; put crude o-phenylenediamine into rectifying tower after slicing and carry out vacuum decompression rectification, remove fore fraction and tar when the temperature of rectifying tower top is constant at 130 ℃, obtain liquid A; put liquid A into rectifying tower for secondary rectification, collect liquid B at rectifying tower top; liquid B is transported to crystallization kettle, adds antioxidant, stir and mix, cooling crystallization, suction filtration, drying, obtain antioxidant o-phenylenediamine. The antioxidant o-phenylenediamine obtained by production technology of the present invention can be exposed to air under the conditions of 25 ± 5 ℃ for 72‑73h without discoloration.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of o-phenylenediamine, and in particular relates to a production process of antioxidant o-phenylenediamine. Background Art

[0002] O-phenylenediamine is an aromatic amine with the molecular formula C6H4(NH2)2, also known as "1,2-phenylenediamine". It is a colorless monoclinic crystal at room temperature, and its color becomes darker in the air. Since the 1970s, in addition to being a raw material for dyes, o-phenylenediamine has also been the main raw material for producing benzimidazole fungicides such as carbendazim, thiophanate-methyl, mebendazole, and methylthiophanate. Moreover, the benzimidazole compounds derived from o-phenylenediamine can also prevent plastic pollution and improve the strength of resins, which is of great significance for accelerating the development and promotion of antibacterial plastics. Therefore, the demand for benzimidazole agricultural fungicides is increasing, and their proportion is increasing day by day.

[0003] However, pure o-phenylenediamine is a white crystal, which will turn yellow after being exposed to air for a long time, greatly affecting the quality of o-phenylenediamine. At present, with the development of technology, the market demand for high-quality o-phenylenediamine is increasing year by year, and the added value of high-quality products is very high. Therefore, it is necessary to provide a production process for antioxidant o-phenylenediamine. Summary of the invention

[0004] The purpose of the present invention is to provide a production process of antioxidant o-phenylenediamine to solve the technical problem of o-phenylenediamine oxidizing and turning yellow when exposed to air for a long time.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A production process of antioxidant o-phenylenediamine comprises the following steps:

[0007] Step 1: Add skeleton nickel catalyst, o-nitroaniline and methanol to the autoclave, introduce hydrogen to replace the air in the reaction system 3-5 times, stir and heat, introduce hydrogen to increase the pressure in the autoclave to 1.5MPa, close the air inlet valve to react, cool, discharge, and evaporate the solvent methanol to obtain crude o-phenylenediamine;

[0008] Step 2: Slice the crude o-phenylenediamine and put it into a distillation tower for vacuum distillation. When the temperature at the top of the distillation tower is constant at 130° C., remove the front fraction and tar to obtain liquid A;

[0009] Step 3, putting liquid A into a distillation tower for secondary distillation, and collecting liquid B (o-phenylenediamine liquid) at the top of the distillation tower;

[0010] Step 4: transport liquid B to a crystallization kettle, add an antioxidant, stir and mix, cool and crystallize, filter and dry to obtain antioxidant o-phenylenediamine.

[0011] As a further scheme of the present invention, the usage ratio of the skeleton nickel catalyst, o-nitroaniline and methanol in step 1 is 0.05-0.15g:50-150g:200-600mL, the stirring speed is 900-1000r / min, the reaction temperature is 100-105°C, the reaction pressure is 0.8-1.2MPa, and the reaction time is 100-150min.

[0012] As a further embodiment of the present invention, the distillation temperature in step 2 is 124-130°C.

[0013] As a further solution of the present invention, the pressure of the distillation tower in step 3 is 7.89 kPa, and the distillation temperature is 140-210°C.

[0014] As a further embodiment of the present invention, the dosage ratio of the liquid B to the antioxidant in step 4 is 200-600 mL: 0.4-2.4 g, and the antioxidant is sodium thiosulfate.

[0015] Beneficial effects of the present invention:

[0016] The invention is a conventional preparation process and is prior art. The crude o-phenylenediamine obtained by catalytic hydrogenation of o-nitroaniline is distilled, mixed with colorless antioxidant sodium thiosulfate, and further crystallized, filtered and dried to obtain antioxidant o-phenylenediamine.

[0017] Compared with the prior art, the invention is innovative in that: the fore fraction and tar are removed by distillation at 124-130° C.; the remaining liquid A is subjected to secondary distillation to obtain o-phenylenediamine liquid;

[0018] It was further testified that since o-nitroaniline is prepared by catalytic hydrogenation of o-phenylenediamine, since methanol can methylate o-phenylenediamine under the action of the catalyst, it inevitably contains color impurities N-methyl o-phenylenediamine and 2,3-dimethylquinoxaline, and since the boiling point of N-methyl o-phenylenediamine is 123-124°C and the boiling point of 2,3-dimethylquinoxaline is 130°C, they can be removed by distillation at 124-130°C;

[0019] On the other hand, in the prior art, due to the high boiling point of o-phenylenediamine, crude o-phenylenediamine is intermittently distilled under vacuum conditions to remove water and light components from the top of the tower in turn, and then an o-phenylenediamine product is obtained. The o-phenylenediamine product is then mixed with an antioxidant and further crystallized and dried to obtain antioxidant o-phenylenediamine. Colored impurities are not effectively removed, and the presence of impurities will cause o-phenylenediamine to change color. Even if various antioxidants are added to o-phenylenediamine, it is difficult to achieve the desired effect.

[0020] The o-phenylenediamine prepared by the production process of the invention can be exposed to air at 25±5°C for 72-73 hours without changing color. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings.

[0022] Figure 1 This is a photo of the antioxidant o-phenylenediamine produced by the production process of an antioxidant o-phenylenediamine according to Example 1-3 of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] A production process of antioxidant o-phenylenediamine comprises the following steps:

[0026] Step 1: add 0.05g of skeleton nickel catalyst, 50g of o-nitroaniline and 200mL of methanol into the autoclave, introduce hydrogen to replace the air in the reaction system 3 times, stir and heat to 100-105°C at a speed of 900r / min, introduce hydrogen to increase the pressure in the autoclave to 1.5MPa, close the air inlet valve to react (the reaction pressure is 0.8-1.2MPa) for 100min, cool, discharge, and evaporate the solvent methanol to obtain crude o-phenylenediamine;

[0027] Step 2: Slice the crude o-phenylenediamine and put it into a distillation tower for vacuum distillation (distillation temperature is 124-130° C.), remove the front fraction and tar when the temperature at the top of the distillation tower is constant at 130° C., and obtain liquid A;

[0028] Step 3: Put liquid A into a distillation tower (the pressure of the distillation tower is 7.89 kPa) for secondary distillation (the distillation temperature is 140-210° C.), and collect liquid B at the top of the distillation tower;

[0029] Step 4: Transfer 200 mL of liquid B to a crystallization kettle, add 0.4 g of an antioxidant sodium thiosulfate, stir and mix, cool and crystallize, filter and dry to obtain antioxidant o-phenylenediamine.

[0030] Example 2

[0031] A production process of antioxidant o-phenylenediamine comprises the following steps:

[0032] Step 1, add 0.15g skeleton nickel catalyst, 150g o-nitroaniline, 600mL methanol into the autoclave, introduce hydrogen to replace the air in the reaction system 5 times, stir at a speed of 1000r / min and heat to 100-105°C, introduce hydrogen to increase the pressure in the autoclave to 1.5MPa, close the air inlet valve to react (the reaction pressure is 0.8-1.2MPa) for 150min, cool, discharge, and evaporate the solvent methanol to obtain crude o-phenylenediamine;

[0033] Step 2: Slice the crude o-phenylenediamine and put it into a distillation tower for vacuum distillation (distillation temperature is 124-130° C.), remove the front fraction and tar when the temperature at the top of the distillation tower is constant at 130° C., and obtain liquid A;

[0034] Step 3: Put liquid A into a distillation tower (the pressure of the distillation tower is 7.89 kPa) for secondary distillation (the distillation temperature is 140-210° C.), and collect liquid B at the top of the distillation tower;

[0035] Step 4: Transfer 600 mL of liquid B to a crystallization kettle, add 2.4 g of an antioxidant sodium thiosulfate, stir and mix, cool and crystallize, filter and dry to obtain antioxidant o-phenylenediamine.

[0036] Example 3

[0037] A production process of antioxidant o-phenylenediamine comprises the following steps:

[0038] Step 1: add 0.10g of skeleton nickel catalyst, 100g of o-nitroaniline and 400mL of methanol to the autoclave, introduce hydrogen to replace the air in the reaction system 4 times, stir and heat to 100-105°C at a speed of 900r / min, introduce hydrogen to increase the pressure in the autoclave to 1.5MPa, close the air inlet valve to react (the reaction pressure is 0.8-1.2MPa) for 125min, cool, discharge, and evaporate the solvent methanol to obtain crude o-phenylenediamine;

[0039] Step 2: Slice the crude o-phenylenediamine and put it into a distillation tower for vacuum distillation (distillation temperature is 124-130° C.), remove the front fraction and tar when the temperature at the top of the distillation tower is constant at 130° C., and obtain liquid A;

[0040] Step 3: Put liquid A into a distillation tower (the pressure of the distillation tower is 7.89 kPa) for secondary distillation (the distillation temperature is 140-210° C.), and collect liquid B at the top of the distillation tower;

[0041] Step 4: Transfer 400 mL of liquid B to a crystallization kettle, add 1.4 g of an antioxidant sodium thiosulfate, stir and mix, cool and crystallize, filter and dry to obtain antioxidant o-phenylenediamine.

[0042] Comparative Example 1

[0043] Compared with Example 1, the comparative example omits the operation of "adding 0.4 g of antioxidant sodium thiosulfate and stirring to mix" in step 4, that is, no antioxidant is added, and the remaining steps and parameters are the same.

[0044] Comparative Example 2

[0045] A production process of antioxidant o-phenylenediamine comprises the following steps:

[0046] Step 1, add 0.15g skeleton nickel catalyst, 150g o-nitroaniline, 600mL methanol into the autoclave, introduce hydrogen to replace the air in the reaction system 5 times, stir at a speed of 1000r / min and heat to 100-105°C, introduce hydrogen to increase the pressure in the autoclave to 1.5MPa, close the air inlet valve to react (the reaction pressure is 0.8-1.2MPa) for 150min, cool, discharge, and evaporate the solvent methanol to obtain crude o-phenylenediamine;

[0047] Step 2, the crude o-phenylenediamine is sliced ​​and put into a distillation tower (the pressure of the distillation tower is 7.89 kPa) for distillation (the distillation temperature is 140-210° C.), and the liquid B at the top of the distillation tower is collected;

[0048] Step 4: Transfer 600 mL of liquid B to a crystallization kettle, add 2.4 g of an antioxidant sodium thiosulfate, stir and mix, cool and crystallize, filter and dry to obtain antioxidant o-phenylenediamine.

[0049] Performance Testing

[0050] (1) Color test: Observe the antioxidant o-phenylenediamine obtained in Examples 1-3 and record it with photos; please refer to Figure 1 As shown;

[0051] Depend on Figure 1 It can be seen that the antioxidant o-phenylenediamines obtained in Examples 1-3 are all white crystals, which meet the industry standard HG 3310-1999;

[0052] (2) The antioxidant o-phenylenediamine prepared in Example 1-3 and Comparative Example 1-2 was subjected to an antioxidant test: the antioxidant o-phenylenediamine was exposed to air at 25±5° C., and the time when the color began to change was recorded; the results are shown in Table 1.

[0053] Table 1

[0054] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Color change time 73 73 72 2 0

[0055] It can be seen from Table 1 that the antioxidant o-phenylenediamine produced by the antioxidant o-phenylenediamine production process of Examples 1-3 can be exposed to air at 25±5°C for 72-73 hours without changing color, has better antioxidant properties than the antioxidant o-phenylenediamine produced in Comparative Example 1, and has higher quality than Comparative Example 2.

[0056] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0057] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for producing an antioxidant o-phenylenediamine, characterized in that: The steps include: Step 1: Add skeleton nickel catalyst, o-nitroaniline and methanol to the autoclave, introduce hydrogen to replace the air in the reaction system 3-5 times, stir and heat, introduce hydrogen to increase the pressure in the autoclave to 1.5MPa, close the air inlet valve to react, cool, discharge, and evaporate the solvent methanol to obtain crude o-phenylenediamine; Step 2: Slice the crude o-phenylenediamine and put it into a distillation tower for vacuum distillation. When the temperature at the top of the distillation tower is constant at 130° C., remove the front fraction and tar to obtain liquid A; Step 3: Put liquid A into a distillation tower for secondary distillation, and collect liquid B at the top of the distillation tower; Step 4, transporting liquid B to a crystallization kettle, adding an antioxidant, stirring and mixing, cooling and crystallizing, filtering, and drying to obtain antioxidant o-phenylenediamine; The distillation temperature in step 2 is 124-130°C; In step 3, the pressure of the distillation tower is 7.89 kPa, and the distillation temperature is 140-210°C.

2. A process for producing an antioxidant o-phenylenediamine according to claim 1, characterized in that: The usage ratio of the skeleton nickel catalyst, o-nitroaniline and methanol is 0.05-0.15g:50-150g:200-600mL, the stirring speed is 900-1000r / min, the reaction temperature is 100-105°C, the reaction pressure is 0.8-1.2MPa, and the reaction time is 100-150min.

3. A process for producing an antioxidant o-phenylenediamine according to claim 1, characterized in that: The dosage ratio of the liquid B to the antioxidant is 200-600 mL: 0.4-2.4 g, and the antioxidant is sodium thiosulfate.

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