CN114349678B - Continuous industrial production method of N-alkyl-nitrophthalimide - Google Patents
Continuous industrial production method of N-alkyl-nitrophthalimide Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000009776 industrial production Methods 0.000 title claims abstract description 20
- 230000032683 aging Effects 0.000 claims abstract description 68
- 238000006243 chemical reaction Methods 0.000 claims abstract description 39
- 238000006396 nitration reaction Methods 0.000 claims abstract description 29
- 238000010790 dilution Methods 0.000 claims abstract description 28
- 239000012895 dilution Substances 0.000 claims abstract description 28
- 238000001035 drying Methods 0.000 claims abstract description 24
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 24
- 239000002994 raw material Substances 0.000 claims abstract description 20
- 230000032798 delamination Effects 0.000 claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 claims abstract description 16
- 239000007788 liquid Substances 0.000 claims description 89
- 239000000463 material Substances 0.000 claims description 81
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 74
- 239000012074 organic phase Substances 0.000 claims description 57
- 239000000243 solution Substances 0.000 claims description 51
- 238000000926 separation method Methods 0.000 claims description 34
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 33
- 229910017604 nitric acid Inorganic materials 0.000 claims description 32
- 238000002425 crystallisation Methods 0.000 claims description 31
- 230000008025 crystallization Effects 0.000 claims description 31
- 238000002156 mixing Methods 0.000 claims description 30
- 230000007062 hydrolysis Effects 0.000 claims description 28
- 238000006460 hydrolysis reaction Methods 0.000 claims description 28
- 239000002253 acid Substances 0.000 claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 239000002351 wastewater Substances 0.000 claims description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 14
- 239000007787 solid Substances 0.000 claims description 14
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 10
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 9
- VPLDXHDOGVIETL-UHFFFAOYSA-N 2-propan-2-ylisoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(C(C)C)C(=O)C2=C1 VPLDXHDOGVIETL-UHFFFAOYSA-N 0.000 claims description 8
- 230000002431 foraging effect Effects 0.000 claims description 8
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 6
- 230000001546 nitrifying effect Effects 0.000 claims description 6
- DLGAPXQHTIJNJA-UHFFFAOYSA-N 2-(2-methylpropyl)isoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CC(C)C)C(=O)C2=C1 DLGAPXQHTIJNJA-UHFFFAOYSA-N 0.000 claims description 5
- OXMDWHVDKVTUQL-UHFFFAOYSA-N 2-(3-methylbutyl)isoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CCC(C)C)C(=O)C2=C1 OXMDWHVDKVTUQL-UHFFFAOYSA-N 0.000 claims description 5
- JZDSOQSUCWVBMV-UHFFFAOYSA-N 2-ethylisoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CC)C(=O)C2=C1 JZDSOQSUCWVBMV-UHFFFAOYSA-N 0.000 claims description 5
- ZXLYYQUMYFHCLQ-UHFFFAOYSA-N 2-methylisoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(C)C(=O)C2=C1 ZXLYYQUMYFHCLQ-UHFFFAOYSA-N 0.000 claims description 5
- 125000000217 alkyl group Chemical group 0.000 claims description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 5
- 239000002904 solvent Substances 0.000 claims description 5
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 claims description 4
- QUSNBJAOOMFDIB-UHFFFAOYSA-N Ethylamine Chemical compound CCN QUSNBJAOOMFDIB-UHFFFAOYSA-N 0.000 claims description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 4
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 claims description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 4
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims description 4
- WGYKZJWCGVVSQN-UHFFFAOYSA-N propylamine Chemical compound CCCN WGYKZJWCGVVSQN-UHFFFAOYSA-N 0.000 claims description 4
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 claims description 3
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 claims description 3
- DLKDEVCJRCPTLN-UHFFFAOYSA-N 2-butylisoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CCCC)C(=O)C2=C1 DLKDEVCJRCPTLN-UHFFFAOYSA-N 0.000 claims description 2
- RLARUBPTQYKZKA-UHFFFAOYSA-N 2-propylisoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CCC)C(=O)C2=C1 RLARUBPTQYKZKA-UHFFFAOYSA-N 0.000 claims description 2
- DKPFZGUDAPQIHT-UHFFFAOYSA-N Butyl acetate Natural products CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 claims description 2
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 2
- 125000004432 carbon atom Chemical group C* 0.000 claims description 2
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 claims description 2
- 239000011736 potassium bicarbonate Substances 0.000 claims description 2
- 229910000028 potassium bicarbonate Inorganic materials 0.000 claims description 2
- 235000015497 potassium bicarbonate Nutrition 0.000 claims description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 2
- SRFRJCMUBGZTAP-UHFFFAOYSA-N 2-pentylisoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CCCCC)C(=O)C2=C1 SRFRJCMUBGZTAP-UHFFFAOYSA-N 0.000 claims 1
- 239000012527 feed solution Substances 0.000 claims 1
- 229940072395 n-butylphthalimide Drugs 0.000 claims 1
- 239000000047 product Substances 0.000 abstract description 24
- 238000000605 extraction Methods 0.000 abstract description 3
- 239000012467 final product Substances 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract 1
- 238000005086 pumping Methods 0.000 description 51
- 230000003068 static effect Effects 0.000 description 25
- -1 N-methylphthalimide sulfuric acid Chemical compound 0.000 description 20
- 238000001816 cooling Methods 0.000 description 15
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 12
- 238000002360 preparation method Methods 0.000 description 8
- 238000004064 recycling Methods 0.000 description 6
- 239000002699 waste material Substances 0.000 description 5
- JBCHWGTZAAZJKG-UHFFFAOYSA-N 2-methyl-5-nitroisoindole-1,3-dione Chemical compound C1=C([N+]([O-])=O)C=C2C(=O)N(C)C(=O)C2=C1 JBCHWGTZAAZJKG-UHFFFAOYSA-N 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- ZFOUJAHAOQQDPB-UHFFFAOYSA-N 4-nitro-2-propan-2-ylisoindole-1,3-dione Chemical compound C1=CC([N+]([O-])=O)=C2C(=O)N(C(C)C)C(=O)C2=C1 ZFOUJAHAOQQDPB-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
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- 238000010924 continuous production Methods 0.000 description 2
- 208000012839 conversion disease Diseases 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000000802 nitrating effect Effects 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- OFJQZKXNQMOMHY-UHFFFAOYSA-N 2-ethyl-4-nitroisoindole-1,3-dione Chemical compound C1=CC([N+]([O-])=O)=C2C(=O)N(CC)C(=O)C2=C1 OFJQZKXNQMOMHY-UHFFFAOYSA-N 0.000 description 1
- FWIZOFDVGZCRTB-UHFFFAOYSA-N 2-methyl-4-nitroisoindole-1,3-dione Chemical compound C1=CC([N+]([O-])=O)=C2C(=O)N(C)C(=O)C2=C1 FWIZOFDVGZCRTB-UHFFFAOYSA-N 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
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- 238000007599 discharging Methods 0.000 description 1
- 238000010981 drying operation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
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Abstract
The invention discloses a continuous industrial production method of N-alkyl-nitrophthalimide, which comprises the following steps: (1) raw material pretreatment; (2) continuous nitration; (3) aging; (4) dilution delamination; (5) neutralization delamination; (6) crystallizing, separating and drying; the whole production operation process is dynamically and continuously carried out to prepare the N-alkyl-nitro phthalimide. According to the invention, a microchannel reactor is adopted for continuous nitration reaction, and an organic extractant is not required to be used for extraction in the post-treatment process, so that the operation is simple, the safety and the environmental protection are realized, and the prepared product has high yield and high purity (the product purity is more than or equal to 99.5 percent); the whole production process of raw material reaction and post-treatment operation is dynamically and continuously carried out, the production efficiency is high, the labor cost is greatly reduced, the quality of the final product is stable and controllable, and large-scale industrial production can be realized.
Description
Technical Field
The invention relates to the technical field of chemical industry, in particular to a continuous industrial production method of N-alkyl-nitrophthalimide.
Background
N-alkyl-nitrophthalimide is an important chemical intermediate, and has very important roles in the industries of chemical engineering, medical treatment, dye and the like. The structure of the compound is shown as formula I:
I
Wherein R can be alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, amyl and the like.
At present, the method for preparing N-alkyl-nitrophthalimide generally takes N-alkyl phthalimide as a reaction raw material and carries out reaction in the presence of a nitrifying reagent, a catalyst and a dehydrating agent. Chinese patent application CN104086476a discloses a method for preparing 4-nitro-N-methylphthalimide, firstly cooling fuming nitric acid to 5-10 ℃, then dripping concentrated sulfuric acid with a metering ratio, and preparing mixed acid at 10-15 ℃; stirring and dissolving N-methylphthalimide and concentrated sulfuric acid at 0 ℃, dropwise adding mixed acid, reacting for 3-4 hours, extracting nitrites in the reaction by using an organic extractant, and separating an upper organic phase and a lower sulfuric acid solution after layering; recovering the upper organic phase to obtain 4-nitro-N-methylphthalimide, centrifuging, filtering and drying to obtain the finished product. The preparation method adopts a mode of dropwise adding the nitrating agent to carry out intermittent reaction, is similar to the traditional kettle type nitrating technology, is difficult to carry out uniform mass and heat transfer, is difficult to remove reaction heat in time, is easy to cause reaction 'flying temperature', thereby causing safety accidents, and is not suitable for industrial production in the chemical environment.
In recent years, the application of the micro-channel reactor in the nitration reaction is wider and wider, and compared with the conventional kettle-type reactor, the micro-channel reactor has the advantages of small liquid holdup, safety, rapid material heating and heat transfer reaction, uniform material mixing and the like. Chinese patent application CN109305933A discloses a method for preparing N-alkyl-4-nitrophthalimide, which adopts micro-channel reactors with different structures to carry out nitration reaction of N-alkyl phthalimide, and carries out post-treatment operations such as cooling, water washing, filtering, collecting, drying and the like after the reaction is finished, thus preparing the N-methyl-4-nitrophthalimide. However, the preparation method realizes continuity only in the nitration reaction process, the subsequent extraction process of the product is still a traditional intermittent post-treatment mode, the purity of the finally obtained product is low, the requirement of the subsequent reaction on the purity cannot be met, and the product can be used for the next reaction only by further purification; and the post-treatment adopts a water washing mode, so that a large amount of acid waste liquid can be generated, more energy sources are consumed during recovery, and the production cost can be increased; in addition, the batch production process is difficult to control the quality of the final product stably, which is a problem faced in the traditional industrial production at present.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a continuous industrial production method of N-alkyl-nitrophthalimide, which has high reaction yield, high product purity and stable and controllable product quality.
The invention is realized by the following technical scheme:
A continuous industrial production method of N-alkyl-nitrophthalimide, comprising the following steps: (1) raw material pretreatment; (2) continuous nitration; (3) aging; (4) dilution delamination; (5) neutralization delamination; (6) crystallizing, separating and drying;
The whole production operation processes of raw material pretreatment, continuous nitration, aging, dilution layering, neutralization layering, crystallization, separation and drying are dynamically and continuously carried out;
The raw material pretreatment in the step (1) is to add N-alkyl phthalimide into sulfuric acid according to a certain proportion, and obtain an N-alkyl phthalimide sulfuric acid solution after mixing and dissolving; wherein the molar ratio of the N-alkylphthalimide to the sulfuric acid is 1:1-1:10; the pretreatment temperature is 0-100 ℃;
Continuously nitrifying the step (2) to continuously pump the pretreated N-alkylphthalimide sulfuric acid solution and nitric acid into a microchannel reactor according to a certain proportion to mix for nitrifying reaction; wherein the molar ratio of the N-alkyl phthalimide to the nitric acid is 1:1-1:10; the reaction temperature is 30-95 ℃; the mixing residence time of the N-alkylphthalimide sulfuric acid solution and nitric acid in the micro-channel reactor is 5 s-500 s;
Aging in the step (3) is that nitrified materials flowing out of the microchannel reactor are continuously pumped into an aging reactor for aging, the aging temperature is controlled to be 30-200 ℃, the aged materials continuously flow out of the aging reactor, and the residence time in the aging reactor is controlled to be 10-600 min;
The step (4) of dilution and layering is that the materials flowing out from the aging reactor are continuously pumped into a dilution hydrolysis reactor, pure water is simultaneously and continuously pumped in according to a proportion, sulfuric acid concentration is diluted to 10% -85% by mixing the materials for hydrolysis, the hydrolyzed materials enter a first knockout for layering continuously, an upper organic phase and a lower acid solution are formed, and the upper organic phase flows out from the first knockout continuously; wherein the temperature in the dilution hydrolysis reactor and the first knockout is controlled to be 20-100 ℃;
the neutralization layering is that an upper organic phase flowing out of a first knockout is continuously pumped into a neutralization reactor, alkaline feed liquid is continuously pumped in proportion, the pH of the system is adjusted to 6-8 by mixing the alkaline feed liquid with an organic phase, and the neutralized material continuously enters a second knockout for layering to form an upper waste water layer and a lower organic phase, and the lower organic phase continuously flows out of the second knockout; wherein the temperature in the neutralization reactor and the second knockout is controlled to be 20-100 ℃;
And (3) crystallizing, separating and drying in the step (6) to obtain the N-alkyl-nitrophthalimide, wherein a crystallization solvent is added into a crystallization kettle, a lower organic phase flowing out through a second knockout is continuously pumped into the crystallization kettle, solid-liquid separation is carried out after cooling crystallization, and the obtained solid is dried.
The alkyl of the raw material N-alkylphthalimide adopted by the invention can be selected from any one of alkyl groups with 1-10 carbon atoms; specifically, the N-alkylphthalimide may be any one selected from N-methylphthalimide, N-ethylphthalimide, N-N-propylphthalimide, N-isopropylphthalimide, N-N-butylphthalimide, N-isobutylphthalimide, N-N-pentylphthalimide, and N-isopentylphthalimide.
The sulfuric acid in the pretreatment of the raw material in the step (1) is concentrated sulfuric acid with the mass concentration of more than 90%, and the nitric acid in the continuous nitrification in the step (2) is concentrated nitric acid with the mass concentration of more than 90%.
The molar ratio of the N-alkylphthalimide to the nitric acid in the continuous nitration in the step (2) is preferably 1:1.05-1:2.
According to the invention, a microchannel reactor is adopted to carry out continuous nitration reaction of N-alkylphthalimide, the mixing residence time of N-alkylphthalimide sulfuric acid solution and nitric acid in the microchannel reactor is controlled by controlling the pumping speed of raw materials according to the specifications of the microchannel reactor, the conversion rate of the short nitration reaction is low due to the excessive mixing residence time, and the production efficiency is reduced due to the excessive mixing residence time. Preferably, the mixing residence time of the N-alkylphthalimide sulfuric acid solution and nitric acid in the microchannel reactor is 10 s-100 s.
The micro-channel reactor can accurately control the reaction temperature within the required range of the invention, the temperature is too high, so that the reaction byproducts are increased, the temperature is higher than the boiling point of concentrated nitric acid, the pressure of the micro-channel reactor is increased, and the investment of equipment is increased.
The invention carries out aging step after nitration reaction, further makes nitration reaction full, and improves reaction conversion rate. The materials subjected to the nitration reaction through the microchannel reactor are directly and continuously pumped into the ageing reaction kettle for ageing, the ageing finished materials can continuously flow out of the ageing reaction kettle in an overflow mode, and the stay ageing time of the materials in the ageing reactor can be controlled by controlling the pumping speed of the materials according to the specification of the ageing reaction kettle so as to ensure that the reaction conversion rate can be effectively improved in the dynamic continuous production process. In the required aging temperature range, the nitration reaction can reach higher conversion rate, if the temperature is too high, reaction byproducts are increased, and the final target product conversion rate is reduced; preferably, the aging temperature is controlled to be 40-120 ℃.
According to the invention, the dilution and layering of the setting step (4) are added, and pure water with a certain proportion is adopted to dilute the sulfuric acid concentration in the material subjected to the aging reaction to be less than or equal to 85%, so that the target product can be hydrolyzed and separated out from the reaction system, and the purification purpose is achieved; the higher the pure water proportion is, the more favorable for the hydrolysis and precipitation of the target product, but excessive water can generate a large amount of waste acid, so that the energy consumption of acid liquor concentration is increased, and the cost is increased; preferably, the ratio of the pure water to the materials subjected to the aging reaction is that the concentration of sulfuric acid is diluted to 30% -60%, so that the target product can be more completely separated out, and excessive waste acid can not be generated.
Through pumping pure water and aged materials into a dilution hydrolysis reactor continuously according to a certain proportion for hydrolysis, the hydrolyzed materials continuously enter a first knockout and are layered, the upper layer is an organic phase of a target product, the lower layer is waste acid, the feeding speed is controlled according to the specification of the knockout, the upper layer organic phase continuously flows out of the knockout in an overflow mode, layering in the knockout is maintained in a dynamic balance, and the production process is ensured to be dynamically and continuously carried out. The waste acid at the lower layer is collected and can be reused after being concentrated.
And (3) in the neutralization layering, the alkaline feed liquid is used for neutralization to more completely remove the residual acid liquid in the target product. The alkaline feed liquid is selected from any one of sodium carbonate solution, sodium bicarbonate solution, potassium carbonate solution, potassium bicarbonate solution, sodium hydroxide solution, calcium hydroxide solution, methylamine solution, ethylamine solution, ethylenediamine solution or propylamine solution with the pH value of more than 7. The invention provides a preferable operation mode, wherein a PH meter can be arranged at the outlet end of the neutralization reactor, and the PH meter and the feeding speed of alkaline feed liquid are controlled in a linkage manner, so that the proportion of the alkaline feed liquid can be controlled, and the pH value of a final material system is 6-8.
The alkaline feed liquid and the organic phase of the target product are continuously pumped into a neutralization reactor according to a certain proportion to carry out neutralization reaction, the neutralized material continuously enters a second knockout and is layered, the upper layer is a wastewater layer, the lower layer is the organic phase of the target product, and the feeding speed and the discharging speed of the organic phase of the lower layer are controlled according to the specification of the knockout, so that the layering in the knockout is maintained in a dynamic balance, and the dynamic continuous production process is ensured. Recovering the upper waste water layer.
The aging reactor, the dilution hydrolysis reactor and the neutralization reactor are reaction devices with mixing and heat preservation functions; the reaction device with the mixing and heat-preserving functions can be specifically selected from a kettle type reactor with stirring, a tubular type reactor with stirring, a static mixer and the like; different specifications and different types of reactors can be selected according to actual production requirements to realize the invention.
The first liquid separator and the second liquid separator are devices with liquid separating functions, and particularly, a liquid separating column, a liquid separating tower and the like can be selected; according to actual production requirements, different specifications and different types of dispensers can be selected to realize the invention.
The crystallization solvent in the step (6) is selected from any one or more of methyl acetate, ethyl acetate, butyl acetate, methanol, ethanol, isopropanol, acetone and butanone.
According to actual production needs, a plurality of crystallization kettles can be arranged to realize continuous proceeding from crystallization to subsequent solid-liquid separation and drying steps.
And in the step of solid-liquid separation after crystallization, device equipment with a solid-liquid separation function such as a centrifugal machine, a plate frame filter or a suction filtration tank can be selected according to actual production requirements to perform solid-liquid separation operation.
And in the drying step, a rotary drum dryer, a double cone dryer, a fluidized bed, a boiling dryer, a spiral dryer or other devices with equivalent effects can be selected for drying operation according to actual production requirements.
Compared with the prior art, the invention has the following beneficial effects:
The continuous industrial production method of the N-alkyl-nitrophthalimide adopts the microchannel reactor to carry out continuous nitration reaction, does not need to use an organic extractant for extraction in the post-treatment process, has simple operation, is safe and environment-friendly, and has high product yield and high purity (the product purity is more than or equal to 99.5 percent); the whole production process of raw material reaction and post-treatment operation is dynamically and continuously carried out, the production efficiency is high, the labor cost is greatly reduced, the quality of the final product is stable and controllable, and large-scale industrial production can be realized.
Drawings
FIG. 1 is a schematic flow chart of a continuous industrial production method of N-alkyl-nitrophthalimide according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by those skilled in the art without departing from the spirit of the invention, which falls within the scope of the invention.
The reagents used in the examples and comparative examples of the present invention are all commercially available, but are not limited to these materials.
The method for testing the purity of the product comprises the following steps: the invention adopts gas chromatography to test the concentration of the product.
Test conditions:
Chromatographic column: HP-5, 30 mX0.32 mm X0.25. Mu.m;
solvent: dichloromethane;
Concentration: 2mg/ml;
sample inlet temperature: 280 ℃;
The split ratio is 30:1;
column box temperature: the initial temperature is 100 ℃, the residence time is 1min, the temperature is increased to 260 ℃ at the heating speed of 15 ℃/min, and the residence time is 1min;
detector temperature: 280 ℃; air: 400ml/min; h 2: 40ml/min; tail gas: 30ml/min;
Column flow rate: 1.4ml/min.
Example 1
(1) Pretreatment of raw materials: 320kg of N-methylphthalimide and 300kg of concentrated sulfuric acid (the mass fraction is 98%) are put into a preparation kettle, mixed and dissolved, and then heated to 40 ℃ for pretreatment, thus obtaining N-methylphthalimide sulfuric acid solution; wherein, the molar ratio of the N-methyl phthalimide to the sulfuric acid is 1:1.5;
(2) Continuous nitration: continuously pumping the pretreated N-methylphthalimide sulfuric acid solution into a microchannel reactor at a flow rate of 5kg/min and a flow rate of 5.3kg/min by concentrated nitric acid (the mass fraction is 95%) to mix for nitration reaction; wherein the molar ratio of the N-alkylphthalimide to the nitric acid is 1:5, the reaction temperature is 90 ℃, and the mixing residence time of the N-methylphthalimide sulfuric acid solution and the concentrated nitric acid in the microchannel reactor is 60s;
(3) Aging: continuously pumping the nitrified material flowing out of the microchannel reactor into an aging reactor at a flow rate of 10.3kg/min for aging, controlling the aging temperature to be 90 ℃, and continuously flowing out of the aging reactor; the residence time of the materials in the aging reactor is 120min;
(4) Dilution and delamination: continuously pumping the material flowing out of the aging reactor into a dilution hydrolysis reactor at a flow rate of 10.3kg/min, continuously pumping pure water at a flow rate of 5.6kg/min, mixing with the material to dilute the sulfuric acid concentration to 60% for hydrolysis, keeping the temperature in the kettle at 90 ℃, continuously feeding the material into a first liquid separation column after the hydrolysis is completed, keeping the temperature in the liquid separation column at 90 ℃, layering into an upper organic phase and a lower acid liquid, continuously overflowing the upper organic phase from the first liquid separation column, and collecting the lower acid liquid for reuse after concentration;
(5) Neutralization and delamination: continuously pumping an upper organic phase flowing out of a first liquid separating column into a static mixer at a flow rate of 3.5kg/min, continuously pumping 10% sodium carbonate solution according to a certain proportion, keeping the temperature in the static mixer at 90 ℃, arranging a PH meter at the outlet end of the static mixer, forming linkage control with the pumping speed of the sodium carbonate solution, controlling the flow rate of the sodium carbonate solution to enable the pH value of a material flowing out of the outlet end of the static mixer to be 7.5, continuously feeding the neutralized material into a second liquid separating column, keeping the temperature in the liquid separating column at 90 ℃, layering the neutralized material into an upper waste water layer and a lower organic phase, continuously flowing out of the lower organic phase from the second liquid separating column, and simultaneously recycling the upper waste water layer;
(6) Crystallizing, separating and drying: adding 1200kg of methyl acetate into a crystallization kettle, continuously pumping a lower organic phase flowing out through a second liquid separation column into the crystallization kettle for cooling and crystallizing, cooling to room temperature, centrifuging by a centrifuge to separate solid from liquid, and drying the obtained solid wet material by a biconical dryer to obtain N-methyl-nitrophthalimide; the yield was 95.9% and the purity was 99.6%.
Example 2
(1) Pretreatment of raw materials: 320kg of N-isobutyl phthalimide and 640kg of concentrated sulfuric acid (the mass fraction is 98%) are put into a preparation kettle, and mixed and dissolved to obtain N-isobutyl phthalimide sulfuric acid solution; wherein, the mol ratio of the N-isobutyl phthalimide to the sulfuric acid is 1:4;
(2) Continuous nitration: continuously pumping the pretreated N-isobutyl phthalimide sulfuric acid solution into a microchannel reactor at a flow rate of 5.1kg/min and a flow rate of 1.1kg/min by concentrated nitric acid (the mass fraction is 95%) for mixing and carrying out nitration reaction; wherein the molar ratio of the N-isobutyl phthalimide to the nitric acid is 1:2, the reaction temperature is 70 ℃, and the mixing residence time of the N-isobutyl phthalimide sulfuric acid solution and the concentrated nitric acid in the microchannel reactor is 400s;
(3) Aging: continuously pumping the nitrified material flowing out of the microchannel reactor into an aging reactor at a flow rate of 6.2kg/min for aging, controlling the aging temperature to be 70 ℃, and continuously flowing out of the aging reactor after aging; the residence time of the materials in the aging reactor is 240min;
(4) Dilution and delamination: continuously pumping the material flowing out of the aging reactor into a dilution hydrolysis reactor at a flow rate of 6.2kg/min, continuously pumping pure water at a flow rate of 2.27kg/min, mixing with the material to dilute the sulfuric acid concentration to 60% for hydrolysis, keeping the temperature in the kettle at 70 ℃, continuously feeding the material into a first liquid separation column after the hydrolysis is completed, keeping the temperature in the liquid separation column at 70 ℃, layering into an upper organic phase and a lower acid liquid, continuously overflowing the upper organic phase from the first liquid separation column, and collecting the lower acid liquid for reuse after concentration;
(5) Neutralization and delamination: continuously pumping an upper organic phase flowing out of a first liquid separating column into a static mixer at a flow rate of 2.08kg/min, simultaneously continuously pumping 10% sodium hydroxide solution according to a certain proportion, keeping the temperature in the static mixer at 90 ℃, arranging a PH meter at the outlet end of the static mixer, forming linkage control with the pumping speed of the sodium hydroxide solution, controlling the flow rate of the sodium hydroxide solution to ensure that the pH value of a material flowing out of the outlet end of the static mixer is 7.5, continuously feeding the neutralized material into a second liquid separating column, keeping the temperature in the liquid separating column at 70 ℃, layering the neutralized material into an upper waste water layer and a lower organic phase, continuously flowing out of the lower organic phase from the second liquid separating column, and simultaneously recycling the upper waste water layer;
(6) Crystallizing, separating and drying: adding 1200kg of ethyl acetate into a crystallization kettle, continuously pumping a lower organic phase flowing out through a second liquid separation column into the crystallization kettle for cooling and crystallizing, cooling to room temperature, centrifuging by a centrifuge to separate solid from liquid, and drying the obtained solid wet material by a biconical dryer to obtain N-isobutyl-nitrophthalimide; the yield was 95.0% and the purity was 99.8%.
Example 3
(1) Pretreatment of raw materials: 320kg of N-isopropyl phthalimide and 550kg of concentrated sulfuric acid (the mass fraction is 98%) are put into a preparation kettle, mixed and dissolved, and then heated to 60 ℃ for pretreatment, thus obtaining N-isopropyl phthalimide sulfuric acid solution; wherein, the mol ratio of the N-isopropyl phthalimide to the sulfuric acid is 1:3.3;
(2) Continuous nitration: continuously pumping the pretreated N-isopropyl phthalimide sulfuric acid solution into a microchannel reactor at a flow rate of 5.1kg/min and a flow rate of 0.72kg/min by concentrated nitric acid (the mass fraction is 95 percent) to mix for nitration reaction; wherein the molar ratio of the N-isopropyl phthalimide to the nitric acid is 1:1.1, the reaction temperature is 80 ℃, and the mixing residence time of the N-isopropyl phthalimide sulfuric acid solution and the concentrated nitric acid in the micro-channel reactor is 10s;
(3) Aging: continuously pumping the nitrified material flowing out of the microchannel reactor into an aging reactor at a flow rate of 5.82kg/min for aging, controlling the aging temperature to be 80 ℃, and continuously flowing out of the aging reactor; the residence time of the materials in the aging reactor is 240min;
(4) Dilution and delamination: continuously pumping the material flowing out of the aging reactor into a dilution hydrolysis reactor at a flow rate of 5.82kg/min, continuously pumping pure water at a flow rate of 3.2kg/min, mixing with the material to dilute the sulfuric acid concentration to 50% for hydrolysis, keeping the temperature in the kettle at 80 ℃, continuously feeding the material into a first liquid separation column after the hydrolysis is completed, keeping the temperature in the liquid separation column at 80 ℃, layering into an upper organic phase and a lower acid liquid, continuously overflowing the upper organic phase from the first liquid separation column, and collecting the lower acid liquid for reuse after concentration;
(5) Neutralization and delamination: continuously pumping an upper organic phase flowing out of a first liquid separating column into a static mixer at a flow rate of 1.95kg/min, continuously pumping 5% potassium hydroxide solution according to a certain proportion, keeping the temperature in the static mixer at 80 ℃, arranging a PH meter at the outlet end of the static mixer, forming linkage control with the pumping speed of the potassium hydroxide solution, controlling the flow rate of the potassium hydroxide solution to enable the pH value of a material flowing out of the outlet end of the static mixer to be 7.5, continuously feeding the neutralized material into a second liquid separating column, keeping the temperature in the liquid separating column at 80 ℃, layering the neutralized material into an upper waste water layer and a lower organic phase, continuously flowing out of the lower organic phase from the second liquid separating column, and simultaneously recycling the upper waste water layer;
(6) Crystallizing, separating and drying: adding 1200kg of ethanol into a crystallization kettle, continuously pumping a lower organic phase flowing out through a second liquid separation column into the crystallization kettle for cooling crystallization, cooling to room temperature, centrifuging by a centrifuge to separate solid from liquid, and drying the obtained solid wet material by a biconical dryer to obtain N-isopropyl-nitrophthalimide; the yield was 97.0% and the purity was 99.6%.
Example 4
Example 4 differs from example 3 only in that in the dilution and stratification of step (4), pure water is added in such a ratio that the sulfuric acid concentration in the material is diluted to 70%, specifically as follows:
(1) Pretreatment of raw materials: 320kg of N-isopropyl phthalimide and 550kg of concentrated sulfuric acid (the mass fraction is 98%) are put into a preparation kettle, mixed and dissolved, and then heated to 60 ℃ for pretreatment, thus obtaining N-isopropyl phthalimide sulfuric acid solution; wherein, the mol ratio of the N-isopropyl phthalimide to the sulfuric acid is 1:3.3;
(2) Continuous nitration: continuously pumping the pretreated N-isopropyl phthalimide sulfuric acid solution into a microchannel reactor at a flow rate of 5.1kg/min and a flow rate of 0.72kg/min by concentrated nitric acid (the mass fraction is 95 percent) to mix for nitration reaction; wherein the molar ratio of the N-isopropyl phthalimide to the nitric acid is 1:1.1, the reaction temperature is 80 ℃, and the mixing residence time of the N-isopropyl phthalimide sulfuric acid solution and the concentrated nitric acid in the micro-channel reactor is 10s;
(3) Aging: continuously pumping the nitrified material flowing out of the microchannel reactor into an aging reactor at a flow rate of 5.82kg/min for aging, controlling the aging temperature to be 80 ℃, and continuously flowing out of the aging reactor; the residence time of the materials in the aging reactor is 240min;
(4) Dilution and delamination: continuously pumping the material flowing out of the aging reactor into a dilution hydrolysis reactor at a flow rate of 5.82kg/min, continuously pumping pure water at a flow rate of 1.38kg/min, mixing with the material to dilute the sulfuric acid concentration to 70% for hydrolysis, keeping the temperature in the kettle at 80 ℃, continuously feeding the material into a first liquid separation column after the hydrolysis is completed, keeping the temperature in the liquid separation column at 80 ℃, layering into an upper organic phase and a lower acid liquid, continuously overflowing the upper organic phase from the first liquid separation column, and collecting the lower acid liquid for reuse after concentration;
(5) Neutralization and delamination: continuously pumping an upper organic phase flowing out of a first liquid separating column into a static mixer at a flow rate of 1.95kg/min, continuously pumping 5% potassium hydroxide solution according to a certain proportion, keeping the temperature in the static mixer at 80 ℃, arranging a PH meter at the outlet end of the static mixer, forming linkage control with the pumping speed of the potassium hydroxide solution, controlling the flow rate of the potassium hydroxide solution to enable the pH value of a material flowing out of the outlet end of the static mixer to be 7.5, continuously feeding the neutralized material into a second liquid separating column, keeping the temperature in the liquid separating column at 80 ℃, layering the neutralized material into an upper waste water layer and a lower organic phase, continuously flowing out of the lower organic phase from the second liquid separating column, and simultaneously recycling the upper waste water layer;
(6) Crystallizing, separating and drying: adding 1200kg of ethanol into a crystallization kettle, continuously pumping a lower organic phase flowing out through a second liquid separation column into the crystallization kettle for cooling crystallization, cooling to room temperature, centrifuging by a centrifuge to separate solid from liquid, and drying the obtained solid wet material by a biconical dryer to obtain N-isopropyl-nitrophthalimide; the yield was 90.0% and the purity was 99.6%.
Example 5
(1) Pretreatment of raw materials: 320kg of N-ethyl phthalimide and 1886kg of sulfuric acid (the mass fraction is 95%) are put into a preparation kettle, mixed and dissolved, and then heated to 40 ℃ for pretreatment, thus obtaining N-ethyl phthalimide sulfuric acid solution; wherein, the mol ratio of the N-ethyl phthalimide to the sulfuric acid is 1:10;
(2) Continuous nitration: continuously pumping the pretreated N-ethylphthalimide sulfuric acid solution into a microchannel reactor at a flow rate of 5.1kg/min and a flow rate of 0.56kg/min by concentrated nitric acid (the mass fraction is 95%) for mixing and carrying out nitration reaction; wherein the molar ratio of the N-ethylphthalimide to the nitric acid is 1:2, the reaction temperature is 80 ℃, and the mixing residence time of the N-ethylphthalimide sulfuric acid solution and the concentrated nitric acid in the microchannel reactor is 300s;
(3) Aging: continuously pumping the nitrified material flowing out of the microchannel reactor into an aging reactor at a flow rate of 5.66kg/min for aging, controlling the aging temperature to be 80 ℃, and continuously flowing out of the aging reactor; the residence time of the materials in the aging reactor is 240min;
(4) Dilution and delamination: continuously pumping the material flowing out of the aging reactor into a dilution hydrolysis reactor at a flow rate of 5.66kg/min, continuously pumping pure water at a flow rate of 10.17kg/min, mixing with the material to dilute the sulfuric acid concentration to 30% for hydrolysis, keeping the temperature in the kettle at 80 ℃, continuously feeding the material into a first liquid separation column after the hydrolysis is completed, keeping the temperature in the liquid separation column at 80 ℃, layering into an upper organic phase and a lower acid liquid, continuously overflowing the upper organic phase from the first liquid separation column, and collecting the lower acid liquid for reuse after concentration;
(5) Neutralization and delamination: continuously pumping an upper organic phase flowing out of a first liquid separating column into a static mixer at a flow rate of 0.8kg/min, continuously pumping 5% potassium hydroxide solution according to a certain proportion, keeping the temperature in the static mixer at 80 ℃, arranging a PH meter at the outlet end of the static mixer, forming linkage control with the pumping speed of the potassium hydroxide solution, controlling the flow rate of the potassium hydroxide solution to enable the pH value of a material flowing out of the outlet end of the static mixer to be 7.5, continuously feeding the neutralized material into a second liquid separating column, keeping the temperature in the liquid separating column at 80 ℃, layering the neutralized material into an upper waste water layer and a lower organic phase, continuously flowing out of the lower organic phase from the second liquid separating column, and simultaneously recycling the upper waste water layer;
(6) Crystallizing, separating and drying: adding 1200kg of ethanol into a crystallization kettle, continuously pumping a lower organic phase flowing out through a second liquid separation column into the crystallization kettle for cooling and crystallizing, cooling to room temperature, centrifuging by a centrifuge to separate solid from liquid, and drying the obtained solid wet material by a biconical dryer to obtain N-ethyl-nitrophthalimide; the yield was 96.0% and the purity was 99.7%.
Example 6
(1) Pretreatment of raw materials: 320kg of N-isopentyl phthalimide and 608kg of sulfuric acid (the mass fraction is 95%) are put into a preparation kettle, mixed and dissolved, and then heated to 40 ℃ for pretreatment, so as to obtain an N-isopentyl phthalimide sulfuric acid solution; wherein, the mol ratio of the N-isopentyl phthalimide to the sulfuric acid is 1:4;
(2) Continuous nitration: continuously pumping the pretreated N-isopentyl phthalimide sulfuric acid solution into a microchannel reactor at a flow rate of 5.1kg/min and a flow rate of 2.69kg/min for mixing and nitrifying reaction; wherein the molar ratio of the N-isopentyl phthalimide to the nitric acid is 1:5, the reaction temperature is 75 ℃, and the mixing residence time of the N-isopentyl phthalimide sulfuric acid solution and the concentrated nitric acid in the microchannel reactor is 300s;
(3) Aging: continuously pumping the nitrified material flowing out of the microchannel reactor into an aging reactor at a flow rate of 7.79kg/min for aging, controlling the aging temperature to be 75 ℃, and continuously flowing out of the aging reactor; the residence time of the materials in the aging reactor is 240min;
(4) Dilution and delamination: continuously pumping the material flowing out of the aging reactor into a dilution hydrolysis reactor at a flow rate of 7.79kg/min, continuously pumping pure water at a flow rate of 7.79kg/min, mixing with the material to dilute the sulfuric acid concentration to 30% for hydrolysis, keeping the temperature in the kettle at 60 ℃, continuously feeding the material into a first liquid separation column after the hydrolysis is completed, keeping the temperature in the liquid separation column at 60 ℃, layering into an upper organic phase and a lower acid liquid, continuously overflowing the upper organic phase from the first liquid separation column, and collecting the lower acid liquid for reuse after concentration;
(5) Neutralization and delamination: continuously pumping an upper organic phase flowing out of a first liquid separating column into a static mixer at a flow rate of 1.8kg/min, simultaneously continuously pumping 5% potassium hydroxide solution according to a certain proportion, keeping the temperature in the static mixer at 60 ℃, arranging a PH meter at the outlet end of the static mixer, forming linkage control with the pumping speed of the potassium hydroxide solution, controlling the flow rate of the potassium hydroxide solution to ensure that the pH value of a material flowing out of the outlet end of the static mixer is 7.5, continuously feeding the neutralized material into a second liquid separating column, keeping the temperature in the liquid separating column at 60 ℃, layering the neutralized material into an upper waste water layer and a lower organic phase, continuously flowing out of the lower organic phase from the second liquid separating column, and simultaneously recycling the upper waste water layer;
(6) Crystallizing, separating and drying: adding 1200kg of ethanol into a crystallization kettle, continuously pumping a lower organic phase flowing out through a second liquid separation column into the crystallization kettle for cooling crystallization, cooling to room temperature, centrifuging by a centrifuge to separate solid from liquid, and drying the obtained solid wet material by a biconical dryer to obtain N-isopentyl-nitrophthalimide; the yield was 96.8% and the purity was 99.6%.
As can be seen from the above examples, the continuous industrial production method of N-alkyl-nitrophthalimide of the present invention can realize that the whole production process from raw material reaction and post-treatment operation is dynamically and continuously carried out, after continuous nitration reaction, the post-treatment steps of aging, dilution layering, neutralization layering, crystallization, separation and drying are dynamically and continuously carried out, so that the yield and purity of the product can be effectively improved, the purity of the prepared product reaches 99.5% or more, and the product can be directly used in the next reaction; meanwhile, the product quality can be ensured to be stable and controllable.
Claims (7)
1. A continuous industrial production method of N-alkyl-nitrophthalimide, which is characterized by comprising the following steps: (1) raw material pretreatment; (2) continuous nitration; (3) aging; (4) dilution delamination; (5) neutralization delamination; (6) crystallizing, separating and drying;
The whole production operation processes of raw material pretreatment, continuous nitration, aging, dilution layering, neutralization layering, crystallization, separation and drying are dynamically and continuously carried out;
The raw material pretreatment in the step (1) is to add N-alkyl phthalimide into sulfuric acid according to a certain proportion, and obtain an N-alkyl phthalimide sulfuric acid solution after mixing and dissolving; wherein the molar ratio of the N-alkylphthalimide to the sulfuric acid is 1:1-1:10; the pretreatment temperature is 0-100 ℃;
Continuously nitrifying the step (2) to continuously pump the pretreated N-alkylphthalimide sulfuric acid solution and nitric acid into a microchannel reactor according to a certain proportion to mix for nitrifying reaction; wherein the molar ratio of the N-alkyl phthalimide to the nitric acid is 1:1-1:10; the reaction temperature is 30-95 ℃; the mixing residence time of the N-alkylphthalimide sulfuric acid solution and nitric acid in the micro-channel reactor is 10 s-100 s;
aging in the step (3) is that nitrified materials flowing out of the microchannel reactor are continuously pumped into an aging reactor for aging, the aging temperature is controlled to be 40-120 ℃, the aged materials continuously flow out of the aging reactor, and the residence time in the aging reactor is controlled to be 10-240 min;
The step (4) of dilution and layering is that the materials flowing out from the aging reactor are continuously pumped into a dilution hydrolysis reactor, pure water is simultaneously and continuously pumped in according to a proportion, sulfuric acid concentration is diluted to 10% -85% by mixing the materials for hydrolysis, the hydrolyzed materials enter a first knockout for layering continuously, an upper organic phase and a lower acid solution are formed, and the upper organic phase flows out from the first knockout continuously; wherein the temperature in the dilution hydrolysis reactor and the first knockout is controlled to be 20-100 ℃;
the neutralization layering is that an upper organic phase flowing out of a first knockout is continuously pumped into a neutralization reactor, alkaline feed liquid is continuously pumped in proportion, the pH of the system is adjusted to 6-8 by mixing the alkaline feed liquid with an organic phase, and the neutralized material continuously enters a second knockout for layering to form an upper waste water layer and a lower organic phase, and the lower organic phase continuously flows out of the second knockout; wherein the temperature in the neutralization reactor and the second knockout is controlled to be 20-100 ℃;
The step (6) of crystallization, separation and drying is to add a crystallization solvent into a crystallization kettle, continuously pump a lower organic phase flowing out through a second knockout into the crystallization kettle, cool and crystallize, perform solid-liquid separation, and dry the obtained solid to prepare N-alkyl-nitrophthalimide;
The alkyl of the N-alkylphthalimide in the step (1) is selected from any one of alkyl groups with 1-10 carbon atoms.
2. The continuous industrial production method of N-alkyl-nitrophthalimide according to claim 1, wherein the N-alkyl-phthalimide is selected from any one of N-methylphthalimide, N-ethylphthalimide, N-propylphthalimide, N-isopropylphthalimide, N-butylphthalimide, N-isobutylphthalimide, N-pentylphthalimide or N-isopentylphthalimide.
3. The continuous industrial production method of N-alkyl-nitrophthalimide according to claim 1, wherein the sulfuric acid in step (1) is concentrated sulfuric acid with a mass concentration of more than 90%; the nitric acid in the step (2) is concentrated nitric acid with the mass concentration of more than 90 percent.
4. The continuous industrial production method of N-alkyl-nitrophthalimide according to claim 1, wherein the molar ratio of the N-alkyl-phthalimide to nitric acid in the step (2) is 1:1.05-1:2.
5. The continuous industrial production method of N-alkyl-nitrophthalimide according to claim 1, wherein pure water is pumped in the step (4) to dilute the sulfuric acid concentration of the material to 30% -60%.
6. The continuous industrial production method of N-alkyl-nitrophthalimide according to claim 1, wherein the alkaline feed solution in the step (5) is selected from any one of sodium carbonate solution, sodium bicarbonate solution, potassium carbonate solution, potassium bicarbonate solution, sodium hydroxide solution, calcium hydroxide solution, methylamine solution, ethylamine solution, ethylenediamine solution or propylamine solution having a PH of more than 7.
7. The continuous industrial production method of N-alkyl-nitrophthalimide according to claim 1, wherein the crystallization solvent in the step (6) is selected from any one or more of methyl acetate, ethyl acetate, butyl acetate, methanol, ethanol, isopropanol, acetone or butanone.
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