Purification method of 3, 4-dimethyl-2, 6-dinitro-N-(2-amyl) aniline

Abstract

The invention relates to the technical field of aniline substance purification, in particular to a purification method of 3, 4-dimethyl-2, 6-dinitro-N-(2-amyl) aniline, which comprises the following steps: step 1, adding a 3, 4-dimethyl-2, 6-dinitro-N-(2-amyl) aniline crude product into a first reaction kettle, adding a hydrochloric acid solution, fully mixing, reacting for 1-4 hours, and discharging reaction liquid; 2, heating the discharged reaction liquid, collecting the volatilized hydrogen chloride gas, and collecting the reaction liquid into a second reaction kettle; 3, a hydrochloric acid solution continues to be added into the first reaction kettle containing the 3, 4-dimethyl-2, 6-dinitro-N-(2-amyl) aniline crude product, according to the purification method, the 3, 4-dimethyl-2, 6-dinitro-N-(2-amyl) aniline crude product is gradually dissolved through hydrochloric acid, a small amount of organic impurities in separation liquid are removed through activated carbon, and the purity of the 3, 4-dimethyl-2, 6-dinitro-N-(2-amyl) aniline is improved. Finally, the 3, 4-dimethyl-2, 6-dinitro-N-(2-amyl) aniline salt is converted into 3, 4-dimethyl-2, 6-dinitro-N-(2-amyl) aniline through an alkali solution, purification is completed, and the whole process is convenient and rapid.

Description

Technical Field

[0001] The invention relates to the technical field of aniline purification, in particular to a method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline. Background Art

[0002] Pendimethalin is a dinitroaniline herbicide that is mainly absorbed by the germinating weed shoots, binds to the microtubule protein in the plant body, inhibits plant cell mitosis, and thus causes the death of weeds. It is mainly used in a variety of dry fields including cotton, corn, etc. and dry rice seedling fields.

[0003] In the synthesis process of pendimethalin, due to the presence of a small amount of 2-pentanone impurity in the raw materials, 2-pentanone will eventually react with 3,5-dinitro-4-chloro-o-xylene to generate 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline. Studies have found that 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline has certain effects in the fields of pesticides, coatings, plastics, etc. During the synthesis process of 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline, some raw materials will be over-nitrated to generate nitrosamines, which have a serious impact on the quality of the product. Therefore, we propose a purification method for 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings in the prior art and to provide a method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0005] A method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline comprises the following steps:

[0006] Step 1, adding crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline into the first reaction kettle, adding hydrochloric acid solution, mixing thoroughly, reacting for 1-4 hours, and discharging the reaction liquid;

[0007] Step 2, heating the discharged reaction liquid, collecting the volatilized hydrogen chloride gas, and collecting the reaction liquid into a second reaction kettle;

[0008] Step 3, continue to add hydrochloric acid solution to the first reaction kettle containing crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline, react for 1-4 hours, and then discharge the reaction liquid;

[0009] Step 4, repeating step 2 and step 3 until the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the first reaction kettle is completely reacted;

[0010] Step 5, adding activated carbon to the reaction liquid collected in the second reactor, stirring sufficiently, filtering, and collecting the filtrate into the third reactor;

[0011] Step 6: Add an alkaline solution into the third reaction kettle to react fully. After the reaction is complete, filter and wash the precipitate generated in the third reaction kettle, collect the precipitate, and dry the precipitate to obtain purified 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0012] In the step 1 and step 3, the reaction temperature is 20-40°C.

[0013] In the step 2, when the discharged reaction liquid is heated, the heating temperature is 80-95°C.

[0014] In step 2, the collected hydrogen chloride gas is absorbed by deionized water and can be reused.

[0015] In the step 1, the concentration of the hydrochloric acid solution is 0.5-2 mol / L. In the step 6, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the alkaline solution is 0.5-2 mol / L.

[0016] In the step 5, the amount of activated carbon added is 1% to 5% of the crude quality of 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0017] In step 6, the reaction temperature in the third reaction kettle is controlled at 20-40°C.

[0018] In step 4, whether the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline is completely reacted can be determined by monitoring the COD change of the solution in the first reaction kettle.

[0019] The beneficial effects of the present invention are:

[0020] 1. The purification method proposed by the present invention comprises the following steps: using hydrochloric acid to gradually dissolve a crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline to generate a 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline salt, so that the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline salt is separated from insoluble nitrosamine substances, and a small amount of organic impurities in the separation liquid is removed by activated carbon, and finally the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline salt is converted into 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline by an alkaline solution to complete the purification, and the whole process is convenient and fast.

[0021] 2. The purification method proposed by the present invention adopts a volatile hydrochloric acid solution to participate in the reaction. During the purification process, the discharged reaction liquid is heated and the volatilized hydrogen chloride gas is collected, which can reduce the subsequent use of alkaline solution. At the same time, the collected hydrogen chloride gas is absorbed by deionized water and can be reused, thereby improving the utilization rate of raw materials. DETAILED DESCRIPTION

[0022] The present invention will be further explained below in conjunction with specific embodiments.

[0023] In Example 1, a method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline comprises the following steps:

[0024] Step 1, adding crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline into the first reaction kettle, adding hydrochloric acid solution, mixing thoroughly, reacting for 1 hour, and discharging the reaction liquid;

[0025] Step 2, heating the discharged reaction liquid, collecting the volatilized hydrogen chloride gas, and collecting the reaction liquid into a second reaction kettle;

[0026] Step 3, continue to add hydrochloric acid solution into the first reaction kettle containing crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline, react for 1 hour, and then discharge the reaction liquid;

[0027] Step 4, repeating step 2 and step 3 until the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the first reaction kettle is completely reacted;

[0028] Step 5, adding activated carbon to the reaction liquid collected in the second reactor, stirring sufficiently, filtering, and collecting the filtrate into the third reactor;

[0029] Step 6: Add an alkaline solution into the third reaction kettle to react fully. After the reaction is complete, filter and wash the precipitate generated in the third reaction kettle, collect the precipitate, and dry the precipitate to obtain purified 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0030] In the step 1 and step 3, the reaction temperature is 20°C.

[0031] In the step 2, when the discharged reaction liquid is heated, the heating temperature is 80°C.

[0032] In step 2, the collected hydrogen chloride gas is absorbed by deionized water and can be reused.

[0033] In the step 1, the concentration of the hydrochloric acid solution is 0.5 mol / L. In the step 6, the alkaline solution is a potassium hydroxide solution, and the concentration of the alkaline solution is 0.5 mol / L.

[0034] In the step 5, the amount of activated carbon added is 1% of the crude quality of 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0035] In step 6, the reaction temperature in the third reactor is controlled at 20°C.

[0036] In step 4, whether the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline is completely reacted can be determined by monitoring the COD change of the solution in the first reaction kettle.

[0037] In Example 2, a method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline comprises the following steps:

[0038] Step 1, adding crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline into the first reaction kettle, adding hydrochloric acid solution, mixing thoroughly, reacting for 4 hours, and discharging the reaction liquid;

[0039] Step 2, heating the discharged reaction liquid, collecting the volatilized hydrogen chloride gas, and collecting the reaction liquid into a second reaction kettle;

[0040] Step 3, continue to add hydrochloric acid solution into the first reaction kettle containing crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline, react for 4 hours, and then discharge the reaction liquid;

[0041] Step 4, repeating step 2 and step 3 until the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the first reaction kettle is completely reacted;

[0042] Step 5, adding activated carbon to the reaction liquid collected in the second reactor, stirring sufficiently, filtering, and collecting the filtrate into the third reactor;

[0043] Step 6: Add an alkaline solution into the third reaction kettle to react fully. After the reaction is complete, filter and wash the precipitate generated in the third reaction kettle, collect the precipitate, and dry the precipitate to obtain purified 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0044] In the step 1 and step 3, the reaction temperature is 40°C.

[0045] In the step 2, when the discharged reaction liquid is heated, the heating temperature is 95°C.

[0046] In step 2, the collected hydrogen chloride gas is absorbed by deionized water and can be reused.

[0047] In the step 1, the concentration of the hydrochloric acid solution is 2 mol / L. In the step 6, the alkaline solution is a sodium hydroxide solution, and the concentration of the alkaline solution is 2 mol / L.

[0048] In the step 5, the amount of activated carbon added is 5% of the crude quality of 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0049] In step 6, the reaction temperature in the third reactor is controlled at 40°C.

[0050] In step 4, the COD change of the solution in the first reaction kettle can be monitored to determine whether the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline has been completely reacted.

[0051] In Example 3, a method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline comprises the following steps:

[0052] Step 1, adding crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline into the first reaction kettle, adding hydrochloric acid solution, mixing thoroughly, reacting for 1-4 hours, and discharging the reaction liquid;

[0053] Step 2, heating the discharged reaction liquid, collecting the volatilized hydrogen chloride gas, and collecting the reaction liquid into a second reaction kettle;

[0054] Step 3, continue to add hydrochloric acid solution to the first reaction kettle containing crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline, react for 1-4 hours, and then discharge the reaction liquid;

[0055] Step 4, repeating step 2 and step 3 until the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the first reaction kettle is completely reacted;

[0056] Step 5, adding activated carbon to the reaction liquid collected in the second reactor, stirring sufficiently, filtering, and collecting the filtrate into the third reactor;

[0057] Step 6: Add an alkaline solution into the third reaction kettle to react fully. After the reaction is complete, filter and wash the precipitate generated in the third reaction kettle, collect the precipitate, and dry the precipitate to obtain purified 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0058] In the step 1 and step 3, the reaction temperature is 30°C.

[0059] In the step 2, when the discharged reaction liquid is heated, the heating temperature is 90°C.

[0060] In step 2, the collected hydrogen chloride gas is absorbed by deionized water and can be reused.

[0061] In the step 1, the concentration of the hydrochloric acid solution is 1 mol / L, and in the step 6, the alkaline solution is a sodium hydroxide solution, and the concentration of the alkaline solution is 1 mol / L.

[0062] In the step 5, the amount of activated carbon added is 3% of the crude quality of 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

[0063] In step 6, the reaction temperature in the third reactor is controlled at 30°C.

[0064] In step 4, the COD change of the solution in the first reaction kettle can be monitored to determine whether the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline is completely reacted. When the solid content in the first reaction kettle remains substantially unchanged, the COD of the solution is detected every 10 minutes. If the change is less than 5%, it indicates that the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline is completely reacted.

[0065] Main reaction formula:

[0066]

[0067] Wherein, reaction formula (1) and reaction formula (2) are the main reaction formulas for the synthesis of 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline; reaction formula (3) is the main reaction process of step 1; and reaction formula (4) is the main reaction process of step 6.

[0068] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline, characterized in that: The following steps are involved: Step 1, adding crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline into the first reaction kettle, adding hydrochloric acid solution, mixing thoroughly, reacting for 1-4 hours, and discharging the reaction liquid; Step 2, heating the discharged reaction liquid, collecting the volatilized hydrogen chloride gas, and collecting the reaction liquid into a second reaction kettle; Step 3, continue to add hydrochloric acid solution to the first reaction kettle containing crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline, react for 1-4 hours, and then discharge the reaction liquid; Step 4, repeating step 2 and step 3 until the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the crude 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline in the first reaction kettle is completely reacted; Step 5, adding activated carbon to the reaction liquid collected in the second reactor, stirring sufficiently, filtering, and collecting the filtrate into the third reactor; Step 6: Add an alkaline solution into the third reaction kettle to react fully. After the reaction is complete, filter and wash the precipitate generated in the third reaction kettle, collect the precipitate, and dry the precipitate to obtain purified 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

2. A method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline according to claim 1, characterized in that: In the step 1 and step 3, the reaction temperature is 20-40°C.

3. A method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline according to claim 1, characterized in that: In the step 2, when the discharged reaction liquid is heated, the heating temperature is 80-95°C.

4. A method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline according to claim 1, characterized in that: In step 2, the collected hydrogen chloride gas is absorbed by deionized water and can be reused.

5. A method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline according to claim 1, characterized in that: In the step 1, the concentration of the hydrochloric acid solution is 0.5-2 mol / L. In the step 6, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the alkaline solution is 0.5-2 mol / L.

6. A method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline according to claim 1, characterized in that: In the step 5, the amount of activated carbon added is 1% to 5% of the crude quality of 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline.

7. A method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline according to claim 1, characterized in that: In step 6, the reaction temperature in the third reaction kettle is controlled at 20-40°C.

8. The method for purifying 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline according to claim 1, characterized in that: In step 4, whether the 3,4-dimethyl-2,6-dinitro-N-(2-pentyl)aniline is completely reacted can be determined by monitoring the COD change of the solution in the first reaction kettle.

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