CN114920685A - Continuous synthesis method of N-alkyl-4-nitrophthalimide - Google Patents
Continuous synthesis method of N-alkyl-4-nitrophthalimide Download PDFInfo
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- CN114920685A CN114920685A CN202210613406.1A CN202210613406A CN114920685A CN 114920685 A CN114920685 A CN 114920685A CN 202210613406 A CN202210613406 A CN 202210613406A CN 114920685 A CN114920685 A CN 114920685A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D209/00—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
- C07D209/02—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
- C07D209/44—Iso-indoles; Hydrogenated iso-indoles
- C07D209/48—Iso-indoles; Hydrogenated iso-indoles with oxygen atoms in positions 1 and 3, e.g. phthalimide
Abstract
Disclosed is a continuous synthesis method of N-alkyl-4-nitrophthalimide, comprising (i) mixing a strong acid solution of N-alkyl phthalimide with nitric acid to obtain a mixed solution; (ii) feeding the mixed solution into an extrusion flow reactor to react at the temperature of 30-80 ℃ for 4-20 minutes to obtain a reaction product; the inner diameter phi of the plug flow reactor is 0.5-15.0 mm; the length is 500-15,000 mm; the reaction product is substantially free of polynitrogen.
Description
Technical Field
The invention relates to a continuous synthesis method for preparing N-alkyl-4-nitrophthalimide, which can greatly improve the production efficiency and shorten the reaction retention time, and can also greatly reduce the 3-nitro compound of a side reaction product in a final reaction mixture and basically does not contain polynitro compound.
Background
N-alkyl-4-nitro phthalimide is an important monomer for synthesizing polyimide resin and is also an excellent modifier for various resins, and can be used for preparing polyimide, disperse dyes, synthetic resin intermediates and products, and the final products are applied to the fields of aerospace, printing and dyeing, pharmacy and the like.
One method of preparing N-alkyl-4-nitrophthalimide is to introduce a nitro group into N-alkylphthalimide by nitration, the reaction equation of which is as follows:
the nitration reaction is to introduce nitro group into organic compound molecular template material, i.e. N-alkyl phthalimide or substrate material, and to utilize the electron withdrawing property of nitro group to nitrify other substituent on aromatic ring.
A method for preparing bis-N-methylphthalimide ether (ODPA) by heating 4 nitro-N-methylphthalimide (4NPI), chinese patent application CN1079734A filed by shanghai institute of synthetic resins (shanghai plastic research institute limited). The raw material 4NPI is produced by the company, N-methylphthalimide is dissolved in a stirring reaction kettle containing concentrated sulfuric acid, nitric acid is slowly dripped into the solution of the reaction kettle, and the batch kettle type mixed acid nitration method is adopted to synthesize the 4 NPI.
Due to the reaction characteristics of the kettle type nitration, the uneven distribution of the components of the kettle type nitration easily causes local overheating to cause reaction runaway. The kettle type reaction is based on the characteristics of 'back mixing', the concentration of raw materials is reduced, and the production efficiency is low; because the temperature is not easy to control and stable, the product selectivity is low, and the byproduct 3-nitro compound (such as N-methyl-3-nitro-phthalimide-3 NPI) is relatively more; the sulfuric acid and nitric acid are excessive, and waste acid is generated. Long reaction time, low volume utilization rate of equipment, high operation cost, environmental protection, production control, product quality and other factors, and is limited in large-scale application.
Chinese patent application CN113396146A describes a process for preparing N- (C) 1-8 A process for the preparation of alkyl) -4-nitrophthalimide by continuous nitration in a microreactor. Compared with the traditional kettle type reaction, the microreactor technology has the advantages of high mass and heat transfer efficiency, safety, reliability and high integration level, and the N- (C) obtained by the method 1-8 Alkyl) -4-nitrophthalimide advantageously reduces the amount of dinitro by-product. As can be seen from the test results, this method can control the amounts of the polynitro byproduct and 3-nitro byproduct to levels of 2.5 to 3.0 wt%, respectively. In addition, this document also mentions that the dinitro by-product can be almost completely destroyed when the reaction temperature exceeds 100 ℃.
Polynitro species (such as 3, 5-dinitro-4-hydroxy-N-alkylphthalimide, DNPI) produced by nitration can lead to a reduction in some key indicators during subsequent conversion to polyimides or synthetic resins and can darken the polymer leading to end product color non-uniformity, poor performance, and impact in applications such as in the aerospace and electronics industries. Clearly there is still a need to further reduce the level of impurities in the product.
In addition, the existing method adopting the microreactor has the defects of high equipment investment and limited production scale. Therefore, there is still a need to develop a continuous synthesis method of N-alkyl-4-nitrophthalimide, which can further reduce the content of product impurities based on the existing microreactor method without using high temperature, and has the advantages of low equipment investment and large production scale.
Disclosure of Invention
One object of the present invention is to provide a method for synthesizing N-alkyl-4-nitrophthalimide, which can further reduce the content of product impurities without using high temperature, and has the advantages of low equipment manufacturing cost, convenient maintenance, flexible production design, long service life and scale effect.
Accordingly, the present invention relates to a continuous process for the synthesis of N-hydrocarbyl-4-nitrophthalimide, comprising the steps of:
mixing the strong acid solution of N-alkyl phthalimide with nitric acid to obtain a mixed solution;
feeding the mixed solution into a plug flow reactor to react at the temperature of 30-80 ℃ for 4-20 minutes to obtain a reaction product;
the inner diameter phi of the plug flow reactor is 0.5-15.0 mm; the length is 500-15,000 mm;
the reaction product is substantially free of polynitrogen.
The invention also relates to the use of a plug flow reactor for nitrating N-alkylphthalimide to synthesize N-alkylphthalimide.
Detailed Description
Plug flow reactors are known to be tubular reactors in which the flow ideally has a strictly uniform radial velocity profile, the material flows forward like a plug (this flow is called plug flow), and there is no back mixing in the reactor. The flow in a practical plug flow reactor can be close to this ideal flow to varying degrees.
The inventors of the present invention have found that, although a microreactor as a tubular reactor has many advantages and is also a type of a plug flow reactor in a broad sense, when a plug flow reactor is used instead of a microreactor in a reaction for producing N-hydrocarbyl-4-nitrophthalimide by nitration, in addition to reduction of equipment investment and enlargement of production scale, the amount of 3-nitro by-products in the product can be further reduced by controlling the residence time and the feed rate, and the object of being substantially free of polynitro by-products can be achieved at a lower reaction temperature. The present invention has been completed on the basis of this finding.
The term "substantially free of polynitro by-products" in the context of the present invention means that the product is not detectable by quantitative analysis by digital Fourier NMR.
The method of the invention involvesSynthesis of N-hydrocarbyl-4-nitrophthalimides, the hydrocarbyl groups comprising groups derived from alkanes and aromatics, e.g. from C 1 -C 6 Preferably C 1 -C 4 Straight or branched chain paraffins and C 6 -C 10 A substituted or unsubstituted aromatic hydrocarbon group.
Non-limiting examples of suitable alkane-derived groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and the like.
Non-limiting examples of suitable aromatic hydrocarbon-derived groups are, for example, phenyl, naphthyl, etc., which may be unsubstituted or derived from C 1 -C 6 Linear or branched paraffins. Non-limiting examples of suitable substituents are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and the like.
1. Mixing the strong acid solution of N-alkyl phthalimide and nitric acid to obtain a mixed solution
The strong acid solution of N-alkylphthalimide comprises a sulfuric acid solution of N-alkylphthalimide.
In one embodiment of the invention, the sulfuric acid forming the strong acid solution is selected from concentrated sulfuric acid with a mass fraction of 90-100%, and fuming sulfuric acid.
In one embodiment of the present invention, the mass ratio of the N-alkylphthalimide (or template) to the sulfuric acid in the strong acid solution of N-alkylphthalimide is in the range of 1:1 to 1:10, preferably 1:1 to 1:8, more preferably 1:1 to 1:6, and most preferably 1:2 to 1: 4.
In one embodiment of the invention, the nitric acid used for mixing with the strong acid solution is selected from concentrated nitric acid and fuming nitric acid with the mass fraction of 60-100%. In one embodiment of the present invention, the molar equivalent ratio (acid-to-oil ratio) of nitric acid to the template material is in the range of 1.03 to 1.80, preferably 1.05 to 1.50, and most preferably 1.07 to 1.30.
The method of mixing both is not particularly limited, and may be any conventional mixing method known in the art.
The mixing step described above may be carried out in a mixer. In one example of the invention the mixer has the following dimensions: the inner diameter phi is 0.5 to 15.0mm, preferably 0.8 to 12.0 mm. In one embodiment of the invention, the mixer comprises an in-line pipe static mixer, and the suitable in-line pipe static mixer can be selected from in-line pipe static mixers with an opening angle of an inner insert of 30-150 °, preferably 45 ° or 60 ° or 90 °.
2. Sending the mixed solution into a plug flow reactor for reaction to obtain a reaction product
The plug flow reactor suitable for the method of the present invention is not particularly limited as long as the inner diameter phi thereof is 0.5 to 15.0mm, preferably 0.8 to 13.0mm, more preferably 1.0 to 10.0 mm; the length is 500 to 15,000mm, preferably 600 to 13,000mm, more preferably 800 to 12,000 mm.
In one embodiment of the invention, the plug flow reactor is jacketed for heat exchange. In another example of the present invention, the plug flow reactor is selected from the group consisting of a single tube (e.g., straight tube, coiled tube, U-tube, etc.) plug flow reactor, a shell and tube tubular plug flow reactor, and any combination thereof, either in series or in parallel.
The material of the suitable plug flow reactor is not particularly limited, and may be conventional material known in the art, and in one example of the present invention, the material includes stainless steel, hastelloy.
In one embodiment of the invention, the reactor inlet of the plug flow reactor is further provided with a sparger. The form of the distributor to be used is not particularly limited, and may be, for example, a ring-shaped distributor, a cross-shaped distributor, or the like.
The reactor internals of the plug flow reactor are not particularly limited, and in one embodiment of the invention, the plug flow reactor is filled with quartz, star-shaped, honeycomb-shaped, cylindrical and the like, and can be a hollow tube.
The process of the invention is carried out at a temperature of from 30 to 80 ℃ and preferably from 45 to 75 ℃ and more preferably from 50 to 65 ℃ with a residence time of the reaction of from 4 to 20 minutes, preferably from 5 to 15 minutes and more preferably from 8 to 12 minutes.
In one embodiment of the invention, the product may dilute the reaction thermal control reaction hot zone temperature at the reactor outlet by recycling a portion of the reflux line to the reactor inlet. In a preferred embodiment of the present invention, the mass ratio of the reflux amount to the discharge amount of the continuous nitration reaction is 0 to 1.0, preferably 0.1 to 0.8, and most preferably 0.2 to 0.7.
In one embodiment of the present invention, the feed temperature is controlled to be 15 to 40 ℃, preferably 20 to 35 ℃.
In one embodiment of the invention, the plug flow reactor may be provided with an external circulation temperature control system for controlling the feed preheat temperature and heat removal during the reaction.
The external circulation medium can be water, heat conduction oil, heat conduction salt and the like, and is better water.
In the method, the conversion rate of the nitration template substance is more than or equal to 95.0 percent, the selectivity of the nitration target product is more than or equal to 90.0 percent, the content of the 3-bit nitro substance of the side reaction product is low, and no multi-nitro substance is found.
In one embodiment of the present invention, the method comprises the steps of: dissolving a template substance N-alkyl-phthalimide into concentrated sulfuric acid, wherein the mass ratio of the template substance to the concentrated sulfuric acid is 1:1.8-2.2, the acid-oil ratio is 1.0-1.2, dissolving the template substance into the concentrated sulfuric acid to form a homogeneous solution, statically mixing the homogeneous solution with nitric acid on line, then entering a plug flow reactor for continuous nitration reaction, and determining the form, the feeding rate and the control range of a circulating temperature control hot zone through the nitration reaction heat to obtain the solution of the N-alkyl-4-nitrophthalimide. After pretreatment, the product is subjected to NMR quantitative analysis by a Digital Fourier nuclear magnetic resonance instrument (Bruker Avance400MHz2-Bay-Digital FT), the conversion rate of a template substance is more than 98.0 percent, the selectivity of the product N-methyl-4-nitrophthalimide is more than 95.0 percent, and polynitro substances are not seen.
The prior art with microreactors (e.g. CN113396146A) has considered that the formation of polynitro substituents during the reaction can only be prevented when the reaction temperature reaches 100 ℃. In fact, a microreactor is also a broad plug flow reactor, and its fine reactor size brings many advantages not possessed by conventional reactors, and is regarded as a potential reactor device. However, the inventors of the present invention have found that for such nitration reactions, the formation of polynitro substituents during the reaction can be effectively prevented at lower temperatures by using the preferred plug flow reactor, which is not mentioned or contemplated by the prior art, thereby reducing the production cost of the product and achieving good economic benefits.
The invention aims to overcome the defects of the prior art and provides a continuous synthesis process for preparing N-alkyl-4-nitrophthalimide by adopting a nitration plug flow reactor. The method of the invention adopts relatively simple equipment structure, can be flexibly adjusted according to different production scales, and is a high-efficiency continuous nitration synthesis method for mass transfer and heat transfer. Through controlling the characteristics of different template substances, the nitration reaction heat of the template substances, the acid-oil ratio, the acid ratio, the retention time, the hot zone temperature and the like, a proper reactor kit (group) and a circulating heat tracing mode are selected pertinently, the template substances complete continuous nitration through the reactor kit, an unexpected result is obtained, the conversion rate and the selectivity reach over 90 percent, the side reaction product 3-position nitro compound is less, and a plurality of nitro compounds are not generated. The process control is safe and reliable, the production efficiency of the product is greatly improved, and the product purity is high.
Compared with the intermittent kettle type nitration method, the plug flow reactor has the advantages of short reaction residence time, more accurate reaction temperature range, safe and reliable process, stable process control, high product yield and small product selectivity fluctuation. Compared with a micro-channel reactor, the device has the advantages of low manufacturing cost, convenient maintenance, flexible capacity design, long service life and scale effect. The invention is not only suitable for small and medium scale, such as medicine and fine chemical industry, but also suitable for large-scale basic chemical industry and petrochemical industry.
Examples
Example 1 (plug flow reactor)
Template material: dissolving N-methyl-phthalimide in concentrated sulfuric acid, wherein the mass ratio of a template substance to the concentrated sulfuric acid is 1:2, the acid-oil ratio is 1.1, dissolving the template substance in the concentrated sulfuric acid to form a homogeneous solution, mixing the homogeneous solution with nitric acid in an online static manner, then entering a plug flow reactor for continuous nitration reaction, and determining the form, the feeding rate and the control range of a circulating temperature control hot zone through the nitration reaction heat. The inner diameter of the mixer and the reactor is phi 10mm, the length of the pipe of the plug flow reactor with the clamp sleeve is 2,000mm, and the mixer and the reactor are made of stainless steel. The feeding temperature is controlled to be 25 ℃, the hot zone temperature of the plug flow reactor is controlled to be 50 ℃, and the retention time is controlled to be 5 min. A solution of N-methyl-4-nitrophthalimide is obtained. After pretreatment, the product was quantitatively analyzed by Digital Fourier nuclear magnetic resonance (Bruker Avance400MHz2-Bay-Digital FT) NMR, and the conversion of the template substance was 98.8%, the selectivity of the product N-methyl-4-nitrophthalimide was 95.6%, and polynitro species were not observed.
Comparative example 1 (kettle reactor)
Template material: dissolving N-methyl-phthalimide in concentrated sulfuric acid, putting the concentrated sulfuric acid into a 500ml flask, starting stirring, putting the flask into a water bath at 25 ℃, slowly dropwise adding nitric acid into the flask, controlling the temperature of the reaction liquid to be not more than 50 ℃ through the temperature of the water bath, keeping the molar ratio of the total addition of the nitric acid to the template substance to be 1.1, and continuously stirring for 1 hour after all the nitric acid is added to obtain the solution of the N-methyl-4-nitrophthalimide. Through nuclear magnetic NMR quantitative analysis, the conversion rate of a template substance is 89.8 percent, the selectivity of the product N-methyl-4-nitrophthalimide is 90.6 percent, and the mass fraction of the impurity polynitro substance is 3.3 percent.
From example 1 and comparative example 1, it can be seen that: in the comparative example 1, nitric acid is intermittently dripped into the kettle reactor, the fluctuation range of the reaction temperature reaches 5-6 ℃, and the fluctuation of different batches is different, so that the batch instability of the product quality is caused. While example 1 uses a plug flow reactor as the synthesis site for the continuous nitration reaction, with the nitric acid being added on-line, the following unexpected results were obtained:
(1) the conversion rate reaches more than 98 percent and is 8 percent higher than that of a batch kettle,
(2) the selectivity of the target product reaches more than 95 percent, is 5 percent higher than that of the batch kettle reaction, has high product purity, the 3-site nitro content of the side reaction product is only half of that of the kettle reaction, and no polynitro impurity exists,
(3) the continuous nitration reaction process is safe, reliable and stable in control.
Example 2
Template material: dissolving N-isopropyl-phthalimide in concentrated sulfuric acid, wherein the mass ratio of the template substance to the concentrated sulfuric acid is 1:5, and the acid-oil ratio is 1.4. Dissolving the template substance in concentrated sulfuric acid to form a homogeneous solution, and statically mixing the homogeneous solution with nitric acid on line, and then entering a plug flow reactor for continuous nitration reaction. The inner diameter of the mixer and the reactor is phi 6mm, the length of the pipe of the plug flow reactor with the clamp sleeve is 3,000mm, and the mixer and the reactor are made of stainless steel. The feeding temperature is controlled to be 35 ℃, the hot zone temperature of the plug flow reactor is controlled to be 75 ℃, and the retention time is controlled to be 10 min. A solution of N-isopropyl-4-nitrophthalimide is obtained. Quantitative analysis by nuclear magnetic NMR showed that the conversion of the template material was 96.9%, the selectivity of the product was 94.1%, and no polynitro species was observed.
Example 3
Template material: dissolving N-phenyl-phthalimide in concentrated sulfuric acid, wherein the mass ratio of a template substance to the concentrated sulfuric acid is 1:5, the acid-oil ratio is 1.5, dissolving the template substance in the concentrated sulfuric acid to form a homogeneous solution, mixing the homogeneous solution with nitric acid in an online static manner, and then entering an extrusion flow reactor for continuous nitration reaction, wherein the reflux ratio is controlled within the range of 0.3-0.5. The inner diameter of the mixer and the reactor is 10mm, the length of the pipe of the plug flow reactor with the clamp sleeve is 5,000mm, and the mixer and the reactor are made of stainless steel. The feeding temperature is controlled at 40 ℃, the hot zone temperature of the plug flow reactor is controlled at 80 ℃, and the retention time is controlled for 12 min. A solution of N-phenyl-4-nitrophthalimide is obtained. Quantitative analysis by nuclear magnetic NMR showed that the conversion of the template material was 97.5%, the selectivity of the product was 93.2%, and no polynitro species was observed.
Example 4
Template material: dissolving N-N-butyl-phthalimide in concentrated sulfuric acid, wherein the mass ratio of a template substance to the concentrated sulfuric acid is 1:4, the acid-oil ratio is 1.5, dissolving the template substance in the concentrated sulfuric acid to form a homogeneous solution, and performing online static mixing with nitric acid and then entering an extrusion flow reactor for continuous nitration reaction. The inner diameter of the mixer and the reactor is phi 15mm, the length of the pipe of the plug flow reactor with the clamp sleeve is 2,000mm, and the mixer and the reactor are made of stainless steel. The feeding temperature is controlled at 30 ℃, the temperature of the hot zone of the plug flow reactor is controlled at 70 ℃, and the retention time is controlled for 15 min. Obtaining the solution of N-butyl-4-nitrophthalimide. Quantitative analysis by nuclear magnetic NMR showed that the conversion of the template material was 96.1%, the selectivity of the product was 95.1%, and no polynitro species was observed.
Example 5
Template material: dissolving N-sec-butyl-phthalimide in concentrated sulfuric acid, wherein the mass ratio of a template substance to the concentrated sulfuric acid is 1:6, the acid-oil ratio is 1.3, dissolving the template substance in the concentrated sulfuric acid to form a homogeneous solution, mixing the homogeneous solution with nitric acid in an online static manner, and then entering an extrusion flow reactor for continuous nitration reaction, wherein the reflux ratio is controlled within the range of 0.2-0.3. The inner diameter of the mixer and the reactor is 10mm, the length of the pipe of the plug flow reactor with the clamp sleeve is 3,000mm, and the mixer and the reactor are made of stainless steel. The feeding temperature is controlled at 30 ℃, the hot zone temperature of the plug flow reactor is controlled at 65 ℃, and the retention time is controlled for 20 min. A solution of N-sec-butyl-4-nitrophthalimide is obtained. Quantitative analysis by nuclear magnetic NMR shows that the conversion rate of the template substance is 97.0 percent, the selectivity of the product is 94.7 percent, and polynitro substances are not seen.
Claims (10)
1. A method for synthesizing N-alkyl-4-nitrophthalimide comprises the following steps:
(i) mixing a strong acid solution of N-alkyl phthalimide with nitric acid to obtain a mixed solution;
(ii) feeding the mixed solution into a plug flow reactor to react at the temperature of 30-80 ℃ for 4-20 minutes to obtain a reaction product;
the inner diameter phi of the plug flow reactor is 0.5-15.0 mm; the length is 500-15,000 mm;
the reaction product is substantially free of polynitrogen.
2. The method of claim 1, wherein said hydrocarbon group is selected from the group consisting of alkyl and aryl derived from an alkane selected from the group consisting of C 1 -C 6 Preferably C 1 -C 4 Linear or branched paraffins, the aromatic hydrocarbon being selected from C 6 -C 10 A substituted or unsubstituted aromatic hydrocarbon group.
3. The method of claim 2, wherein the alkane is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl;
the arene is selected from benzene, which may be unsubstituted or substituted with a group selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, or combinations thereof.
4. The synthesis process according to any one of claims 1 to 3, characterized in that the strong acid is selected from sulfuric acid;
it is preferable that
The sulfuric acid for forming the strong acid solution is selected from concentrated sulfuric acid with the mass fraction of 90-100% and fuming sulfuric acid;
the mass ratio of the N-alkyl phthalimide to the sulfuric acid in the strong acid solution of the N-alkyl phthalimide is 1:1 to 1:10, preferably 1:2 to 1: 6.
5. The synthesis method according to claim 4, characterized in that the plug flow reactor is provided with an external circulation temperature control system for controlling the feed preheating temperature and the heat removal in the reaction process;
the external circulation medium can be water, heat transfer oil, and the like, and is preferably water.
6. The synthesis method according to any one of claims 1 to 3, characterized in that the nitric acid used for mixing with the strong acid solution is selected from concentrated nitric acid and fuming nitric acid with a mass fraction of 60-100%;
the molar equivalent ratio of the nitric acid to the N-alkylphthalimide is in the range of 1.05 to 1.80, preferably 1.05 to 1.50.
7. The synthesis process according to any one of claims 1 to 3, characterized in that step (i) is carried out in a mixer having the following dimensions: the inner diameter is 0.5-15.0 mm, preferably 0.8-12.0 mm; the opening angle of the inner plug is 30-150 degrees; the inner diameter phi of the plug flow reactor is preferably 0.8-13.0 mm, more preferably 1.0-10.0 mm; the length is 600 to 13,000mm, preferably 800 to 12,000 mm.
The reactor is a reactor with a heat exchange jacket;
the reactor comprises a single tube, and can be a straight tube, a coil, a U-shaped tube, a tubular reactor and any combination of the series connection or the parallel connection of the tubular reactors.
8. A synthesis process according to any one of claims 1 to 3, characterised in that it is carried out at a temperature of from 45 to 75 ℃, preferably from 50 to 65 ℃, and in that the reaction residence time is from 5 to 15 minutes, preferably from 8 to 12 minutes.
9. A synthesis process according to any one of claims 1 to 3, characterised in that the feed temperature is controlled between 15 and 40 ℃, preferably between 20 and 35 ℃.
10. Use of a plug flow reactor for nitrating N-alkylphthalimide to synthesize N-alkyl-4-nitrophthalimide.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106083732A (en) * | 2016-06-22 | 2016-11-09 | 袁氏(宿迁)生物技术有限公司 | A kind of preparation method of high yield different luminol luminescence reagent |
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| CN114349678A (en) * | 2021-11-24 | 2022-04-15 | 珠海派锐尔新材料有限公司 | Continuous industrial production method of N-alkyl-nitrophthalimide |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106083732A (en) * | 2016-06-22 | 2016-11-09 | 袁氏(宿迁)生物技术有限公司 | A kind of preparation method of high yield different luminol luminescence reagent |
| CN109305933A (en) * | 2018-10-30 | 2019-02-05 | 浙江万丰化工有限公司 | A method of preparing N- alkyl -4- nitrophthalimide |
| CN112679358A (en) * | 2020-12-29 | 2021-04-20 | 常州大学 | Method for continuously preparing 3, 5-dinitrobenzoic acid by using microchannel reactor |
| CN114349678A (en) * | 2021-11-24 | 2022-04-15 | 珠海派锐尔新材料有限公司 | Continuous industrial production method of N-alkyl-nitrophthalimide |
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