o-Nitroaniline purification process

Abstract

The invention discloses a kind of o-nitroaniline purification process, belong to the field of purification technology, comprise the following steps:The first step, prepare adsorbent:Hydrotalcite-like substance and absolute ethanol are mixed, vinyl trimethylsiloxane is added, stirring 30min, pH is adjusted, stirring reaction 4h, obtains carrier;Cetyl trimethyl ammonium bromide is added in deionized water, under the condition of temperature being 40 DEG C, carrier, methacryloyloxyethyl trimethyl ammonium chloride, unsaturated monomer, N, N-methylene bisacrylamide and benzoyl peroxide are added while stirring, stirring reaction, obtains adsorbent;Second step, adsorption treatment:Adsorbent is added to the o-nitroaniline crude product prepared, carries out adsorption treatment.The present invention, by adding adsorbent in the purification process of the conventional purification process of o-nitroaniline, by the chloride ion in adsorbent adsorption crude product, improves o-nitroaniline purity, meets the requirement of subsequent workshop section.

Description

Technical Field

[0001] The invention belongs to the technical field of purification, and in particular relates to a process for purifying o-nitroaniline. Background Art

[0002] o-Nitroaniline, a basic chemical raw material, is an intermediate for many dyes, pesticides, and pharmaceuticals, and is also used in additives and other fields. The current o-nitroaniline preparation method involves mixing o-nitrochlorobenzene and ammonia water in an ammoniation reaction vessel under high temperature and high pressure to produce o-nitroaniline, ammonium chloride, and water. After separating the aqueous phase from the ammoniation product, the remaining product is washed several times with process hot water to remove the ammonium chloride, and then vacuum dried to obtain o-nitroaniline. Since o-nitroaniline is slightly soluble in water, some o-nitroaniline is dissolved and carried away by water with each water washing. Moreover, even after several water washings, the chloride ions dispersed in the o-nitroaniline cannot be completely removed, resulting in a low o-nitroaniline yield, poor product purity, and a high chloride ion content. Since o-nitroaniline is mainly used in the subsequent process to prepare o-phenylenediamine through hydrogenation, the hydrogenation reaction has very high requirements for the quality of o-nitroaniline. Therefore, the quality of o-nitroaniline currently cannot meet the requirements of the subsequent process. In addition, this method produces a large amount of difficult-to-treat ammonium chloride wastewater, which corrodes pipelines and affects the normal operation of workshop equipment. Summary of the Invention

[0003] The object of the present invention is to provide a process for purifying o-nitroaniline.

[0004] The invention solves the problems of high chloride ion content and low purity of o-nitroaniline.

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

[0006] The o-nitroaniline purification process comprises the following steps:

[0007] Step 1: Prepare the adsorbent: Mix hydrotalcite-like substance and anhydrous ethanol, stir and disperse, add vinyl trimethylsiloxane, stir at 20-30°C for 30 minutes, add ammonia water to adjust the pH value to 4, maintain the temperature at 40°C, continue stirring and react for 4 hours, and after the reaction is completed, filter and dry to obtain a carrier;

[0008] Hexadecyltrimethylammonium bromide was added to deionized water, and a carrier, methacryloyloxyethyltrimethylammonium chloride, an unsaturated monomer, N,N-methylenebisacrylamide, and benzoyl peroxide were added while stirring at 40°C. The mixture was stirred at 75°C for 5 hours. After the reaction, the mixture was washed with deionized water and ethanol in sequence, and dried at 70°C under vacuum to constant weight to obtain an adsorbent.

[0009] Step 2: adsorption treatment: adding an adsorbent to the prepared crude o-nitroaniline product, carrying out adsorption treatment at a temperature of 30°C. After the adsorption is completed, the o-nitroaniline is obtained by concentrating under reduced pressure.

[0010] Furthermore, in the first step, the usage ratio of hydrotalcite-like compound, vinyl trimethylsiloxane and anhydrous ethanol is 1 g:9 g:100 mL; the usage ratio of hexadecyl trimethyl ammonium bromide, deionized water, carrier, methacryloyloxyethyl trimethyl ammonium chloride, unsaturated monomer, N,N-methylene bisacrylamide and benzoyl peroxide is 0.04 g:60 mL:20 g:5 g:5 g:0.2 g:0.25 g.

[0011] Furthermore, the unsaturated monomer is one of methyl methacrylate and butyl acrylate or a mixture of the two in any proportion.

[0012] Furthermore, the amount of adsorbent added is 1-2 g / L.

[0013] Furthermore, the crude o-nitroaniline product is obtained by the following steps:

[0014] o-Chloronitrobenzene and liquid ammonia are mixed to undergo an ammonolysis reaction to obtain a mixed solution containing o-nitroaniline, ammonium chloride and water. Unreacted liquid ammonia is recovered by a pressure relief method, and a solvent is added after recovery. The ammonium chloride is then removed by filtration to obtain a crude o-nitroaniline product.

[0015] Furthermore, the solvent is one of benzene and toluene.

[0016] Furthermore, the reaction conditions of the ammonolysis reaction are a gauge pressure of 7-8 MPa, a temperature of 160-180° C., and a reaction time of 8-10 h.

[0017] Beneficial effects of the present invention:

[0018] The invention adds an adsorbent to the purification process of the conventional o-nitroaniline purification process, and the adsorbent adsorbs chloride ions in the crude product, thereby improving the purity of the o-nitroaniline and meeting the requirements of subsequent work sections.

[0019] The catalyst of the present invention uses a hydrotalcite-like substance as a carrier and treats the hydrotalcite-like substance through a polymerization reaction to improve the adsorption capacity and regeneration degree. The hydrotalcite-like substance itself has a certain adsorption capacity, but its adsorption efficiency is limited and cannot meet industrial needs. In the present invention, a quaternary ammonium group is introduced to dissociate hydroxide ions, adsorb chloride ions, and perform dechlorination, which not only improves the dechlorination efficiency but also facilitates the regeneration of the adsorbent. DETAILED DESCRIPTION

[0020] 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 embodiments described 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0021] Example 1

[0022] This embodiment provides a hydrotalcite-like substance, which is prepared by the following steps:

[0023] 20g of CO(NH2)2 was added to 100mL of 50% aqueous ethanol. 6.40g of Mg(NO3)2, 6H20, and 3.75g of Al(NO3)3·9H20 were added to 100mL of deionized water. The two solutions were mixed and stirred at 50°C for 20 minutes. The mixed solution was transferred to a polytetrafluoroethylene-lined crystallization kettle and placed in an oven. After crystallization at 150°C for 12 hours, the kettle was removed and cooled to room temperature. The resulting precipitate was filtered, washed repeatedly with deionized water several times, and dried at 100°C for 6 hours to obtain a hydrotalcite-like substance.

[0024] Example 2

[0025] This embodiment provides a process for purifying o-nitroaniline, comprising the following steps:

[0026] The first step is to prepare an adsorbent: the hydrotalcite-like substance prepared in Example 1 is mixed with anhydrous ethanol, stirred and dispersed, and vinyl trimethylsiloxane is added. The mixture is stirred at 20°C for 30 minutes, and ammonia is added to adjust the pH value to 4. The temperature is maintained at 40°C and the stirring reaction is continued for 4 hours. After the reaction is completed, the mixture is filtered and dried to obtain a carrier; wherein the amount ratio of hydrotalcite-like substance, vinyl trimethylsiloxane and anhydrous ethanol is 1g:9g:100mL;

[0027] Hexadecyltrimethylammonium bromide is added to deionized water, and a carrier, methacryloyloxyethyltrimethylammonium chloride, an unsaturated monomer, N,N-methylenebisacrylamide and benzoyl peroxide are added while stirring at 40°C. The mixture is stirred and reacted at 75°C for 5 hours. After the reaction, the mixture is washed with deionized water and ethanol in sequence, and dried to a constant weight at 70°C under vacuum to obtain an adsorbent. The amount ratio of hexadecyltrimethylammonium bromide, deionized water, carrier, methacryloyloxyethyltrimethylammonium chloride, unsaturated monomer, N,N-methylenebisacrylamide and benzoyl peroxide is 0.04g:60mL:20g:5g:5g:0.2g:0.25g; the unsaturated monomer is methyl methacrylate.

[0028] Step 2: Adsorption treatment: o-chloronitrobenzene and liquid ammonia are mixed to undergo an ammonolysis reaction. The reaction conditions for the ammonolysis reaction are a gauge pressure of 7 MPa, a temperature of 160°C, and a reaction time of 8 hours. A mixed solution containing o-nitroaniline, ammonium chloride, and water is obtained. Unreacted liquid ammonia is recovered by a pressure relief method, and toluene is added after recovery. The ammonium chloride is then removed by filtration to obtain a crude o-nitroaniline product. The dosage ratio of o-chloronitrobenzene to toluene is 1:5.

[0029] An adsorbent was added to the prepared crude o-nitroaniline product in an amount of 1 g / L. Adsorption treatment was performed at a temperature of 30° C. After the adsorption was completed, o-nitroaniline was obtained by concentrating under reduced pressure.

[0030] Example 3

[0031] This embodiment provides a process for purifying o-nitroaniline, comprising the following steps:

[0032] The first step is to prepare an adsorbent: the hydrotalcite-like substance prepared in Example 1 is mixed with anhydrous ethanol, stirred and dispersed, and vinyl trimethylsiloxane is added. The mixture is stirred at 25°C for 30 minutes, and ammonia is added to adjust the pH value to 4. The temperature is maintained at 40°C and the stirring reaction is continued for 4 hours. After the reaction is completed, the mixture is filtered and dried to obtain a carrier. The ratio of hydrotalcite-like substance, vinyl trimethylsiloxane and anhydrous ethanol is 1g:9g:100mL.

[0033] Hexadecyltrimethylammonium bromide is added to deionized water, and a carrier, methacryloyloxyethyltrimethylammonium chloride, an unsaturated monomer, N,N-methylenebisacrylamide and benzoyl peroxide are added while stirring at 40°C. The mixture is stirred and reacted at 75°C for 5 hours. After the reaction, the mixture is washed with deionized water and ethanol in sequence, and dried to a constant weight at 70°C under vacuum to obtain an adsorbent. The amount ratio of hexadecyltrimethylammonium bromide, deionized water, carrier, methacryloyloxyethyltrimethylammonium chloride, unsaturated monomer, N,N-methylenebisacrylamide and benzoyl peroxide is 0.04g:60mL:20g:5g:5g:0.2g:0.25g; the unsaturated monomer is butyl acrylate.

[0034] Step 2: Adsorption treatment: o-chloronitrobenzene and liquid ammonia are mixed to undergo an ammonolysis reaction. The reaction conditions for the ammonolysis reaction are a gauge pressure of 9 MPa, a temperature of 170°C, and a reaction time of 9 hours. A mixed solution containing o-nitroaniline, ammonium chloride, and water is obtained. Unreacted liquid ammonia is recovered by a pressure relief method, and toluene is added after recovery. The ammonium chloride is then removed by filtration to obtain a crude o-nitroaniline product. The dosage ratio of o-chloronitrobenzene to toluene is 1:5.

[0035] An adsorbent was added to the prepared crude o-nitroaniline product in an amount of 1.5 g / L. Adsorption treatment was carried out at a temperature of 30° C. After the adsorption was completed, o-nitroaniline was obtained by concentrating under reduced pressure.

[0036] Example 4

[0037] This embodiment provides a process for purifying o-nitroaniline, comprising the following steps:

[0038] The first step is to prepare an adsorbent: the hydrotalcite-like substance prepared in Example 1 is mixed with anhydrous ethanol, stirred and dispersed, and vinyl trimethylsiloxane is added. The mixture is stirred at 30°C for 30 minutes, and ammonia is added to adjust the pH value to 4. The temperature is maintained at 40°C and the stirring reaction is continued for 4 hours. After the reaction is completed, the mixture is filtered and dried to obtain a carrier. The ratio of hydrotalcite-like substance, vinyl trimethylsiloxane and anhydrous ethanol is 1g:9g:100mL.

[0039] Hexadecyltrimethylammonium bromide is added to deionized water, and a carrier, methacryloyloxyethyltrimethylammonium chloride, an unsaturated monomer, N,N-methylenebisacrylamide and benzoyl peroxide are added while stirring at 40°C. The mixture is stirred and reacted at 75°C for 5 hours. After the reaction, the mixture is washed with deionized water and ethanol in sequence, and dried to a constant weight under vacuum at 70°C to obtain an adsorbent. The amount ratio of hexadecyltrimethylammonium bromide, deionized water, carrier, methacryloyloxyethyltrimethylammonium chloride, unsaturated monomer, N,N-methylenebisacrylamide and benzoyl peroxide is 0.04g:60mL:20g:5g:5g:0.2g:0.25g; the unsaturated monomer is a mixture of methyl methacrylate and butyl acrylate in a mass ratio of 2:3.

[0040] Step 2: Adsorption treatment: o-chloronitrobenzene and liquid ammonia are mixed to undergo ammonolysis reaction. The reaction conditions for the ammonolysis reaction are a gauge pressure of 8 MPa, a temperature of 180°C, and a reaction time of 10 hours. A mixed solution containing o-nitroaniline, ammonium chloride, and water is obtained. Unreacted liquid ammonia is recovered by a pressure relief method, and toluene is added after recovery. The ammonium chloride is then removed by filtration to obtain a crude o-nitroaniline product. The dosage ratio of o-chloronitrobenzene to toluene is 1:5.

[0041] An adsorbent was added to the prepared crude o-nitroaniline product in an amount of 2 g / L. Adsorption treatment was carried out at a temperature of 30° C. After the adsorption was completed, o-nitroaniline was obtained by concentrating under reduced pressure.

[0042] Comparative Example 1

[0043] Compared with Example 4, this comparative example is different from Example 4 in that the adsorbent is replaced with the hydrotalcite-like substance prepared in Example 1, and the other raw materials and preparation process remain the same as those in Example 4.

[0044] The samples prepared in Examples 2 to 4 and Comparative Example 1 were tested for purity and chloride ion content. After adsorption, the adsorbent was recovered and rinsed with a 4% sodium hydroxide aqueous solution at a flow rate of 5 m / h for 30 min. The regeneration degree was recorded. The regeneration degree was calculated as the saturated adsorption capacity S. 吸 and the amount of chloride ions desorbed S 解 The relationship between regeneration degree (%) and S 解 / S 吸 .

[0045] The results are shown in Table 1:

[0046] Table 1

[0047] project Example 2 Example 3 Example 4 Comparative Example 1 Gas chromatography purity / % ＞99.98 ＞99.98 ＞99.98 ＜99.98 <![CDATA[Cl - Content]]> <50ppm <50ppm <50ppm >50ppm Regeneration rate / % 93.7 94.4 94.8 85.4

[0048] As can be seen from Table 1, the present invention provides a purification process for o-nitroaniline that can well adsorb chloride ions in o-nitroaniline. The prepared product has higher purity and can meet the requirements of subsequent processes. In addition, the prepared adsorbent has high regeneration and good reuse rate.

[0049] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0050] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A process for purifying o-nitroaniline, characterized in that: The steps include: Step 1: Prepare the adsorbent: Mix hydrotalcite-like substance and anhydrous ethanol, add vinyl trimethylsiloxane, stir at 20-30°C for 30 minutes, adjust the pH value to 4, maintain the temperature at 40°C, and continue stirring for 4 hours to obtain a carrier; add hexadecyl trimethyl ammonium bromide into deionized water, and add the carrier, methacryloyloxyethyl trimethyl ammonium chloride, unsaturated monomer, N, N-methylene bisacrylamide and benzoyl peroxide while stirring at 40°C, and stir at 75°C. The mixture was stirred and reacted for 5 hours to obtain an adsorbent; the amount ratio of hydrotalcite-like substance, vinyl trimethylsiloxane and anhydrous ethanol was 1 g:9 g:100 mL; the amount ratio of hexadecyl trimethyl ammonium bromide, deionized water, carrier, methacryloyloxyethyl trimethyl ammonium chloride, unsaturated monomer, N,N-methylene bisacrylamide and benzoyl peroxide was 0.04 g:60 mL:20 g:5 g:5 g:0.2 g:0.25 g; the unsaturated monomer was one or two of methyl methacrylate and butyl acrylate mixed in any proportion; The hydrotalcite-like substance is prepared by the following steps: 20 g of CO(NH2)2 was added to 100 mL of 50% ethanol aqueous solution, and 6.40 g of Mg(NO3)2·6H2O and 3.75 g of Al(NO3)3·9H2O were added to 100 mL of deionized water. The two solutions were mixed and stirred at 50°C for 20 min. The mixed solution was transferred to a crystallization kettle lined with polytetrafluoroethylene and placed in an oven. After constant temperature crystallization at 150°C for 12 h, the crystallization kettle was taken out and cooled to room temperature. The resulting precipitate was filtered, washed repeatedly with deionized water several times, and dried at 100°C for 6 h to obtain a hydrotalcite-like substance. Step 2: adsorption treatment: adding an adsorbent to the prepared crude o-nitroaniline product, carrying out adsorption treatment at a temperature of 30°C. After the adsorption is completed, the o-nitroaniline is obtained by concentrating under reduced pressure.

2. The o-nitroaniline purification process according to claim 1, wherein The amount of adsorbent added is 1-2 g / L.

3. The o-nitroaniline purification process according to claim 1, wherein The crude o-nitroaniline product is obtained by the following steps: o-Chloronitrobenzene and liquid ammonia are mixed to undergo an ammonolysis reaction to obtain a mixed solution containing o-nitroaniline, ammonium chloride and water. Unreacted liquid ammonia is recovered by a pressure relief method, and a solvent is added after recovery. The ammonium chloride is then removed by filtration to obtain a crude o-nitroaniline product.

4. The o-nitroaniline purification process according to claim 3, wherein: The solvent is one of benzene and toluene.

5. The o-nitroaniline purification process according to claim 3, wherein: The reaction conditions of the ammonolysis reaction are: gauge pressure of 7-8 MPa, temperature of 160-180° C., and reaction time of 8-10 h.