Recovery and treatment method for by-products of 4,4-dinitrodiphenyl ether

Abstract

The present invention provides a method for recovering and treating a 4,4-dinitrodiphenyl ether by-product, and belongs to the technical field of organic synthesis. The present invention adjusts the pH value to 3-4 to remove substances that can react with acid in the by-product salt, and the functions of ferrous sulfate and the first activated carbon are to decolorize and remove the color of the 4,4-dinitrodiphenyl ether material. The pH value is then adjusted to 6-8 to remove ferrous sulfate, and then a second decolorization is performed to obtain a white solid salt. The function of hydrogen peroxide is to remove organic matter in the reaction, and the resin column elution ensures that p-chloronitrobenzene, sodium p-nitrophenolate, and DNP organic matter are completely removed. Finally, a solid salt having a sodium chloride content of ≥99.1g / 100g and a TOC (total organic carbon) of less than 50mg / kg is obtained. The obtained solid salt does not have the odor of p-nitrochlorobenzene, meets the industrial salt standard, and realizes the recovery and use of the 4,4-dinitrodiphenyl ether by-product, thereby reducing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a method for recovering and treating 4,4-dinitrodiphenyl ether by-products. Background Art

[0002] 4,4-Dinitrodiphenyl ether is an important intermediate in the synthesis of polyimide. Polyimide is one of the most thermally stable polymers to date and has excellent mechanical properties, high radiation resistance, and good dielectric properties. During the synthesis of 4,4-Dinitrodiphenyl ether, a byproduct is produced, which is a pale yellow powdery solid with a characteristic odor. In existing technologies, this byproduct is directly discharged, resulting in a waste of resources. Summary of the Invention

[0003] In view of this, the present invention aims to provide a method for recovering and treating the byproduct 4,4-dinitrodiphenyl ether. The recovery method of the present invention produces a salt with a sodium chloride content of ≥99.1 g / 100 g and a TOC (total organic carbon) of less than 50 mg / kg, meeting industrial salt standards.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for recovering and treating 4,4-dinitrodiphenyl ether by-products, comprising the following steps:

[0006] The 4,4-dinitrodiphenyl ether by-product is sequentially dried, dissolved in water, and solid-liquid separated to obtain a liquid to be treated;

[0007] The pH value of the liquid to be treated is adjusted to 3-4, and then mixed with ferrous sulfate and first activated carbon for first decolorization to obtain a first decolorized solution;

[0008] The pH value of the first decolorized solution is adjusted to 6-8, followed by solid-liquid separation, and the pH value of the resulting solution is further adjusted to 8-9, followed by a second decolorization with the first activated carbon to obtain a second decolorized solution;

[0009] mixing the second decolorizing solution with hydrogen peroxide and eluting the mixture with a resin column to obtain an eluate;

[0010] The eluate is sequentially distilled and dried to obtain a solid salt.

[0011] Preferably, the amount of water used is 2.5 to 3 times the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0012] Preferably, the amount of the first activated carbon is 0.4-0.5 wt % of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0013] Preferably, the amount of ferrous sulfate used is 0.4-0.5 wt % of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0014] Preferably, the amount of the second activated carbon is 0.4-0.5 wt % of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0015] Preferably, the hydrogen peroxide is added in the form of hydrogen peroxide, the mass ratio of the second decolorizing solution to the hydrogen peroxide is 100:0.4-0.6, and the mass concentration of the hydrogen peroxide is 30%.

[0016] Preferably, the resin column used for the resin column elution includes XDA-1G or Seplite-001.

[0017] Preferably, the eluent for eluting the resin column is a methanol solution.

[0018] Preferably, the distillation is reduced pressure distillation, the vacuum degree of the reduced pressure distillation is -0.08 MPa to -0.09 MPa, and the temperature is 50 to 70°C.

[0019] Preferably, the distillation amount is 1.4 to 1.7 times the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0020] The invention provides a method for recovering and treating a 4,4-dinitrodiphenyl ether by-product. The method comprises the following steps: sequentially drying, dissolving in water, and performing solid-liquid separation on the 4,4-dinitrodiphenyl ether by-product to obtain a liquid to be treated; adjusting the pH value of the liquid to be treated to 3-4, and then mixing the liquid with ferrous sulfate and a first activated carbon to perform a first decolorization to obtain a first decolorization solution; adjusting the pH value of the first decolorization solution to 6-8, and then performing solid-liquid separation; further adjusting the pH value of the obtained solution to 8-9, and then performing a second decolorization with the first activated carbon to obtain a second decolorization solution; mixing the second decolorization solution with hydrogen peroxide, and then performing resin column elution to obtain an eluate; and sequentially distilling and drying the eluate to obtain a solid salt.

[0021] According to the invention, the pH value is adjusted to 3-4 to remove substances that can react with acid in the by-products, the ferrous sulfate and the first activated carbon are used to decolorize and remove the color of the 4,4-dinitrodiphenyl ether material, the pH value is then adjusted to 6-8 to remove the ferrous sulfate, and then a second decolorization is performed to make the obtained solid salt white, the hydrogen peroxide is used to remove oxidized residual organic matter (including p-chloronitrobenzene, sodium p-nitrophenolate, N,N-dimethyl-4-nitroaniline, etc.) in the reaction, and the resin column is used for elution to ensure that p-chloronitrobenzene, sodium p-nitrophenolate and DNP (4,4-dinitrodiphenyl ether) organic matter are completely removed, and finally a solid salt with a sodium chloride content of ≥99.1 g / 100 g and a TOC (total organic carbon) of less than 50 mg / kg is obtained. The obtained solid salt does not have the odor of p-nitrochlorobenzene and meets the industrial salt standard, and the 4,4-dinitrodiphenyl ether by-product can be recycled and reused, thereby reducing costs and improving economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a graph showing the relationship between the solubility of salt in the product after reduced pressure distillation in Example 1 and temperature. DETAILED DESCRIPTION

[0023] The present invention provides a method for recovering and treating 4,4-dinitrodiphenyl ether by-products, comprising the following steps:

[0024] The 4,4-dinitrodiphenyl ether by-product is sequentially dried, dissolved in water, and solid-liquid separated to obtain a liquid to be treated;

[0025] The pH value of the liquid to be treated is adjusted to 3-4, and then mixed with ferrous sulfate and first activated carbon for first decolorization to obtain a first decolorized solution;

[0026] The pH value of the first decolorized solution is adjusted to 6-8, followed by solid-liquid separation, and the pH value of the resulting solution is further adjusted to 8-9, followed by a second decolorization with the first activated carbon to obtain a second decolorized solution;

[0027] mixing the second decolorizing solution with hydrogen peroxide and eluting the mixture with a resin column to obtain an eluate;

[0028] The eluate is sequentially distilled and dried to obtain a solid salt.

[0029] The present invention sequentially performs drying, water dissolution and solid-liquid separation on a 4,4-dinitrodiphenyl ether by-product to obtain a liquid to be treated.

[0030] In the present invention, the 4,4-dinitrodiphenyl ether by-product is preferably obtained from the by-product of preparing 4,4-dinitrodiphenyl ether by using p-chloronitrobenzene and p-nitrophenol as raw materials, DMF as solvent, and sodium chloride and sodium carbonate as catalysts.

[0031] In the present invention, the amount of water used is preferably 2.5 to 3 times the dry weight of the 4,4-dinitrodiphenyl ether by-product. The function of the water is to remove water-insoluble substances.

[0032] The present invention has no particular limitation on the specific methods of drying and solid-liquid separation, and methods well known to those skilled in the art may be used, such as drying and filtering.

[0033] In the present invention, the filtration obtains the liquid to be treated and a filter cake, the liquid to be treated is a yellow relatively clear liquid, the product and unreacted raw materials are obtained on the filter cake, and are preferably recovered. In the present invention, p-chloronitrobenzene, sodium p-nitrophenolate, and N,N-dimethyl-4-nitroaniline are soluble in water, and 4,4-dinitrodiphenyl ether is insoluble in water.

[0034] After obtaining the liquid to be treated, the present invention adjusts the pH value of the liquid to be treated to 3-4 and then mixes it with ferrous sulfate and first activated carbon to perform a first decolorization to obtain a first decolorization solution;

[0035] The present invention preferably uses an acidic substance to adjust the pH to 3-4. The type and concentration of the acidic substance are not particularly limited; any substance familiar to those skilled in the art can be used, specifically, a 30 wt% hydrochloric acid solution. Adjusting the pH to 3-4 removes acid-reactive substances (sodium p-nitrophenolate and sodium carbonate) from the by-product salt of 4-dinitrodiphenyl ether.

[0036] After the pH value is adjusted to 3-4, the present invention further preferably includes stirring for 10 minutes.

[0037] In the present invention, the amount of the first activated carbon is preferably 0.4-0.5 wt % of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0038] In the present invention, the amount of ferrous sulfate used is preferably 0.4-0.5 wt % of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0039] In the present invention, the first activated carbon and ferrous sulfate are used to remove the color of the 4,4-dinitrodiphenyl ether material.

[0040] In the present invention, the function of the ferrous sulfate and the first activated carbon is to decolorize the 4,4-dinitrodiphenyl ether material.

[0041] In the present invention, the first decolorization time is preferably 1 hour, and the first decolorization is preferably performed under stirring. The present invention has no special limitation on the stirring speed.

[0042] After the first decolorization is completed, the present invention preferably filters to filter out the first activated carbon and ferrous sulfate to obtain the first decolorization solution.

[0043] After obtaining the first decolorization solution, the present invention adjusts the pH value of the first decolorization solution to 6-8 and then performs solid-liquid separation, and then adjusts the pH value of the obtained solution to 8-9 and then performs a second decolorization with the first activated carbon to obtain a second decolorization solution.

[0044] The present invention preferably uses liquid caustic soda to adjust the pH value of the first decolorization solution to 6 to 8. The present invention has no particular limitation on the type and concentration of the liquid caustic soda. The function of this step is to ensure that the iron ions are completely removed.

[0045] The present invention preferably uses liquid caustic soda to adjust the pH value of the obtained solution to 8 to 9. The present invention has no particular limitation on the type and concentration of the liquid caustic soda.

[0046] In the present invention, the amount of the second activated carbon is preferably 0.4-0.5 wt % of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0047] In the present invention, the second decolorization process is to ensure that the obtained solid salt has a white appearance.

[0048] In the present invention, the second decolorization time is preferably 1 hour, and the second decolorization is preferably performed under stirring. The present invention has no special limitation on the stirring speed.

[0049] In the present invention, after the second decolorization is completed, filtration is preferably performed to obtain the second decolorized solution.

[0050] After obtaining the second decolorizing solution, the present invention mixes the second decolorizing solution with hydrogen peroxide and then performs elution on a resin column to obtain an eluate.

[0051] In the present invention, the hydrogen peroxide is preferably added in the form of hydrogen peroxide, the mass ratio of the second decolorizing solution to hydrogen peroxide is preferably 100:0.4-0.6, more preferably 100:0.5, and the mass concentration of the hydrogen peroxide is preferably 30%.

[0052] In the present invention, the role of the hydrogen peroxide is to remove organic matter in the reaction.

[0053] In the present invention, the mixing is preferably performed under stirring conditions, the stirring time is preferably 2 to 3 hours, and the stirring temperature is preferably 45 to 65°C.

[0054] In the present invention, the type of resin column used for the resin column elution preferably includes XDA-1G or Seplite-001.

[0055] In the present invention, the eluent for eluting the resin column is preferably a methanol solution, and the mass concentration of the methanol solution is preferably 80-90%.

[0056] In the present invention, the amount of the methanol solution is preferably 2 to 3 times the amount of the resin, and the preferred treatment time of the methanol solution is 1 to 2 hours.

[0057] In the present invention, the resin column is eluted to obtain a desorption liquid, and the desorption liquid is preferably distilled before being used.

[0058] After obtaining the eluate, the present invention sequentially distills and dries the eluate to obtain a solid salt.

[0059] In the present invention, the distillation is preferably reduced pressure distillation, the vacuum degree of the reduced pressure distillation is preferably -0.08 MPa to -0.09 MPa, and the temperature is preferably 50 to 70°C.

[0060] In the present invention, the distilled water obtained by the distillation contains some raw materials (trace amounts of para-chloronitrobenzene), which is harmful to the sewage biochemical pool. Therefore, it is preferably subjected to electrolysis treatment. Preferably, the distilled water is electrolyzed using the potential difference generated by the micro-electrolysis material itself. The hydrogen and iron ions generated during the electrolysis treatment preferably undergo redox reactions with the components in the distilled water, destroying the colored substances in the distilled water and even breaking the chains, thereby achieving the effect of degradation and decolorization, and adsorbing the dispersed tiny particles (including metal particles and organic macromolecules) in the distilled water to meet the biodegradable standards.

[0061] In the present invention, the distillation time is preferably until more salt precipitation is observed and less water is observed (45-50 wt% of water is distilled out), and then the temperature is lowered to ≤30°C and centrifuged to obtain a relatively dry white solid salt, which is then dried to obtain the solid salt (sodium chloride).

[0062] In the present invention, the distillation amount is preferably 1.4 to 1.7 times the dry weight of the 4,4-dinitrodiphenyl ether by-product.

[0063] In the present invention, the drying is preferably oven drying.

[0064] To further illustrate the present invention, the method for recovering and treating the 4,4-dinitrodiphenyl ether by-product provided by the present invention is described in detail below with reference to examples, but these examples should not be construed as limiting the scope of protection of the present invention.

[0065] The 4,4-dinitrodiphenyl ether by-product used in the embodiments of the present invention comes from: a by-product of preparing 4,4-dinitrodiphenyl ether using p-chloronitrobenzene and p-nitrophenol as raw materials, DMF as solvent, and sodium chloride and sodium carbonate as catalysts.

[0066] Example 1:

[0067] Take 500g 4,4-dinitrodiphenyl ether by-product, add 1250g water, stir and dissolve at 60℃ for 1 hour, and filter. The filter cake is DNP and unreacted raw materials, which are recovered. The filtrate is a by-product salt solution, which is a yellow clear liquid. 30% hydrochloric acid is added to the salt solution to adjust the acidity to pH 3. 101g hydrochloric acid is used. After the pH value reaches 3, stirring is continued for 10min. The pH value remains unchanged. 2.5g of ferrous sulfate and activated carbon are added for decolorization. After decolorization and stirring for 1 hour, filter and filter out activated carbon and ferrous sulfate. Adjust the pH value of the filtrate to 6, filter out insoluble matter, adjust the pH value to 8, add 2.5g of activated carbon for secondary decolorization, and decolorize. After stirring for 1 hour, filter, add 30wt% hydrogen peroxide to the filtrate (the mass ratio of wastewater to hydrogen peroxide is 100:0.4), keep warm and stir for 2 hours, enter the resin column (XDA-1G) for reprocessing, and elute with 20g methanol solution (mass fraction 80%) for 1h. The effluent is subjected to vacuum distillation (-0.08MPa, 50℃), 800g of water is evaporated, and the temperature is lowered to 30℃ for filtration to obtain white solid salt. Put it into an oven and dry it at 80℃ for 2 hours to obtain dry white solid sodium chloride. After testing, TOC: 36mg / Kg, sodium chloride content 99.85g / 100g, which meets the "Standard for Regenerated Industrial Salt".

[0068] Figure 1 This is a graph showing the relationship between the solubility of salt in the product after reduced pressure distillation and temperature.

[0069] Example 2:

[0070] Take 500g 4,4-dinitrodiphenyl ether by-product, add 1250g water, stir and dissolve at 70℃ for 1 hour, and filter. The filter cake is DNP and unreacted raw materials, which are recovered. The filtrate is a by-product salt solution, which is a yellow clear liquid. 30% hydrochloric acid is added to the salt solution to adjust the acidity to pH 4. 10g hydrochloric acid is used. After the pH value reaches 4, stirring is continued for 10min. The pH value remains unchanged. 2.5g of ferrous sulfate and activated carbon are added for decolorization. After decolorization and stirring for 1 hour, filter and filter out activated carbon and ferrous sulfate. Adjust the pH value of the filtrate to 7, filter out insoluble matter, adjust the pH value to 9, add 2.5g of activated carbon for secondary decolorization, and decolorize. After stirring for 1 hour, filter, add 30wt% hydrogen peroxide (the mass ratio of wastewater to hydrogen peroxide is 100:0.6) to the filtrate, keep warm and stir for 2 hours, enter the resin column (XDA-1G) for reprocessing, and elute with 20 methanol solution (mass fraction 80%) for 1 hour. The effluent is subjected to vacuum distillation (-0.08MPa, 50℃), 800g of water is evaporated, and the temperature is lowered to 30℃ for filtration to obtain white solid salt. Put it into an oven and dry it at 90℃ for 2 hours to obtain dry white solid sodium chloride. After testing, TOC: 33mg / Kg, sodium chloride content 99.86g / 100g, which meets the "Standard for Regenerated Industrial Salt".

[0071] Example 3:

[0072] Take 500g 4,4-dinitrodiphenyl ether by-product, add 1250g water, stir and dissolve at 80℃ for 1 hour, and filter. The filter cake is DNP and unreacted raw materials, which are recovered. The filtrate is a by-product salt solution, which is a yellow clear liquid. 30% hydrochloric acid is added to the salt solution to adjust the acidity to pH 4. 100g hydrochloric acid is used. After the pH value reaches 4, stirring is continued for 10min. The pH value remains unchanged. 2.5g of ferrous sulfate and activated carbon are added for decolorization. After decolorization and stirring for 1 hour, filter and filter out the activated carbon and ferrous sulfate. The filtrate is adjusted to pH 8, the insoluble matter is filtered out, and the pH is adjusted to 9. 2.5g of activated carbon is added for secondary decolorization. After stirring for 1 hour, the mixture was filtered. 30wt% hydrogen peroxide was added to the filtrate (the mass ratio of wastewater to hydrogen peroxide was 100:0.5). After being kept warm and stirred for 2 hours, the mixture entered a resin column (Seplite-001) for reprocessing and was eluted with 20g methanol solution (mass fraction 80%) for 1h. The effluent was subjected to vacuum distillation (-0.08MPa, 50℃) to evaporate 800g of water. The mixture was cooled to 30℃ and filtered to obtain a white solid salt. The salt was placed in an oven and dried at 80℃ for 2 hours to obtain dry white solid sodium chloride. The TOC was 40mg / Kg and the sodium chloride content was 99.85g / 100g, which met the "Standard for Regenerated Industrial Salt".

[0073] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for recovering and treating 4,4-dinitrodiphenyl ether by-products, characterized in that: The specific steps are as follows: The 4,4-dinitrodiphenyl ether by-product is sequentially dried, dissolved in water, and solid-liquid separated to obtain a liquid to be treated; The pH value of the liquid to be treated is adjusted to 4, and then mixed with ferrous sulfate and first activated carbon for first decolorization to obtain a first decolorized solution; The pH value of the first decolorized solution is adjusted to 7, followed by solid-liquid separation, and the pH value of the resulting solution is adjusted to 9, followed by a second decolorization with a second activated carbon to obtain a second decolorized solution; The second decolorizing solution is mixed with hydrogen peroxide and then eluted with a resin column to obtain an eluent; the eluent used for the resin column elution is a methanol solution; the hydrogen peroxide is added in the form of hydrogen peroxide, the mass ratio of the second decolorizing solution to the hydrogen peroxide is 100:0.6, and the mass concentration of the hydrogen peroxide is 30%; the type of resin column used for the resin column elution is XDA-1G; The eluate is sequentially distilled and dried to obtain a solid salt.

2. The recycling method according to claim 1, characterized in that: The amount of water used is 2.5 to 3 times the dry weight of the 4,4-dinitrodiphenyl ether by-product.

3. The recycling method according to claim 1, characterized in that: The amount of the first activated carbon used is 0.4-0.5 wt % of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

4. The recycling method according to claim 1 or 3, characterized in that: The amount of ferrous sulfate used is 0.4-0.5 wt% of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

5. The recycling method according to claim 1, characterized in that: The amount of the second activated carbon used is 0.4-0.5 wt % of the dry weight of the 4,4-dinitrodiphenyl ether by-product.

6. The recycling method according to claim 1, characterized in that: The distillation is a reduced pressure distillation, the vacuum degree of the reduced pressure distillation is -0.08MPa to -0.09MPa, and the temperature is 50 to 70°C.

7. The recycling method according to claim 1 or 6, characterized in that: The distillation amount is 1.4 to 1.7 times the dry weight of the 4,4-dinitrodiphenyl ether by-product.

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