CN118026850A - Method for continuously preparing 2-chloro-5-nitromethyl phenylacetate - Google Patents
Method for continuously preparing 2-chloro-5-nitromethyl phenylacetate Download PDFInfo
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- CN118026850A CN118026850A CN202410293848.1A CN202410293848A CN118026850A CN 118026850 A CN118026850 A CN 118026850A CN 202410293848 A CN202410293848 A CN 202410293848A CN 118026850 A CN118026850 A CN 118026850A
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- 238000000034 method Methods 0.000 title claims abstract description 45
- IPBVNPXQWQGGJP-UHFFFAOYSA-N acetic acid phenyl ester Natural products CC(=O)OC1=CC=CC=C1 IPBVNPXQWQGGJP-UHFFFAOYSA-N 0.000 title description 3
- 229940049953 phenylacetate Drugs 0.000 title description 3
- WLJVXDMOQOGPHL-UHFFFAOYSA-N phenylacetic acid Chemical compound OC(=O)CC1=CC=CC=C1 WLJVXDMOQOGPHL-UHFFFAOYSA-N 0.000 title description 3
- 239000002253 acid Substances 0.000 claims abstract description 105
- 238000006243 chemical reaction Methods 0.000 claims abstract description 51
- KHBWTRFWQROKJZ-UHFFFAOYSA-N methyl 2-(2-chlorophenyl)acetate Chemical compound COC(=O)CC1=CC=CC=C1Cl KHBWTRFWQROKJZ-UHFFFAOYSA-N 0.000 claims abstract description 46
- 238000006396 nitration reaction Methods 0.000 claims abstract description 26
- 238000002156 mixing Methods 0.000 claims abstract description 15
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 14
- 238000001914 filtration Methods 0.000 claims abstract description 9
- 239000012295 chemical reaction liquid Substances 0.000 claims abstract description 7
- 238000001704 evaporation Methods 0.000 claims abstract description 5
- 230000001546 nitrifying effect Effects 0.000 claims abstract 2
- 239000012071 phase Substances 0.000 claims description 52
- 239000012074 organic phase Substances 0.000 claims description 40
- NMTXRGYKJNMEFK-UHFFFAOYSA-N methyl 2-(2-chloro-5-nitrophenyl)acetate Chemical compound COC(=O)CC1=CC([N+]([O-])=O)=CC=C1Cl NMTXRGYKJNMEFK-UHFFFAOYSA-N 0.000 claims description 37
- 239000007788 liquid Substances 0.000 claims description 26
- -1 polytetrafluoroethylene Polymers 0.000 claims description 21
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 21
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 21
- 238000002360 preparation method Methods 0.000 claims description 14
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 claims description 12
- 239000011148 porous material Substances 0.000 claims description 11
- 239000002904 solvent Substances 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 238000004064 recycling Methods 0.000 claims description 8
- 230000007797 corrosion Effects 0.000 claims description 7
- 238000005260 corrosion Methods 0.000 claims description 7
- 238000007599 discharging Methods 0.000 claims description 4
- 239000000706 filtrate Substances 0.000 claims description 3
- 239000002994 raw material Substances 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 230000007547 defect Effects 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 46
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 19
- 239000000463 material Substances 0.000 description 12
- 239000013078 crystal Substances 0.000 description 11
- 238000001514 detection method Methods 0.000 description 9
- 239000000118 hair dye Substances 0.000 description 9
- 238000001816 cooling Methods 0.000 description 5
- 239000007791 liquid phase Substances 0.000 description 5
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 4
- 239000008346 aqueous phase Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000004821 distillation Methods 0.000 description 4
- 238000005886 esterification reaction Methods 0.000 description 4
- 238000007086 side reaction Methods 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 229940089960 chloroacetate Drugs 0.000 description 2
- 239000012043 crude product Substances 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004043 dyeing Methods 0.000 description 2
- 230000032050 esterification Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000005457 ice water Substances 0.000 description 2
- 239000012452 mother liquor Substances 0.000 description 2
- 239000000049 pigment Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- CRZQGDNQQAALAY-UHFFFAOYSA-N Me ester-Phenylacetic acid Natural products COC(=O)CC1=CC=CC=C1 CRZQGDNQQAALAY-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229940106681 chloroacetic acid Drugs 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000005112 continuous flow technique Methods 0.000 description 1
- 230000032798 delamination Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 125000000449 nitro group Chemical group [O-][N+](*)=O 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000012265 solid product Substances 0.000 description 1
- 230000000638 stimulation Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/141—Feedstock
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for continuously preparing 2-chloro-5-methyl nitroacetate, which comprises the following steps: (a) Respectively carrying out micro-flow mixing on the o-chlorophenylacetic acid methyl ester solution and the mixed acid to carry out nitration reaction to obtain reaction liquid; the mixed acid contains nitric acid, and the molar ratio of the nitric acid to the o-chlorophenylacetic acid methyl ester is 1-1.5: 1, a step of; the flow rate of the o-chloroacetic acid methyl ester solution is larger than that of the mixed acid, the flow rate of the o-chloroacetic acid methyl ester solution is 20-65 ml/min, and the flow rate of the mixed acid is 5.0-35.0 ml/min; (b) Separating, evaporating, concentrating, crystallizing and filtering the reaction liquid to obtain the 2-chloro-5-methyl nitrophenylacetate. The defect that the continuous reaction is required to be carried out for 4-5 hours in a low-temperature environment (-5 ℃) in the process of nitrifying the o-chlorophenylacetic acid methyl ester is effectively overcome, and the consumption of high-level cold public engineering can be greatly reduced, so that the production cost is reduced.
Description
Technical Field
The invention belongs to the technical field of organic synthesis, relates to a synthesis method of 2-chloro-5-nitromethyl acetate, and in particular relates to a method for continuously preparing 2-chloro-5-nitromethyl acetate.
Background
Hair dyes are classified into mineral type hair dyes, natural plant type hair dyes, and chemically synthesized type hair dyes according to different sources of materials. Wherein, the mineral hair dye is gradually eliminated due to the potential harm of heavy metals contained in the mineral hair dye to human bodies; the natural plant pigment has the advantages of complicated extraction steps, low extraction rate and poor stability, and is applied less at present; the chemical synthetic hair dye is the most widely used hair dye at present. The 2-chloro-5-nitrophenylacetic acid methyl ester is an important dye, pigment, macromolecule and pesticide intermediate, is mainly used for synthesizing efficient hair dye, has wide dyeing range (from cyan to purple), has no stimulation, has better regulation effect on hair, has long dyeing time and is not easy to elute, thus having very broad market prospect.
Chinese patent 201811465332.1 discloses a methyl 2-chloro-5-nitrophenylacetate esterification and nitration process method, which comprises the following steps: o-chloroacetic acid and methanol are put into an esterification kettle to carry out an esterification reaction process; pumping the material after the esterification reaction into a nitration kettle, and adding nitric acid and chloroform into the nitration kettle to perform a nitration reaction process; layering the discharged material after the nitration reaction; distilling and separating out the material from the layered material, and recovering chloroform; and finally, cooling and drying the separated material and extracting. However, the nitration reaction is a strong exothermic reaction, and the o-chloroacetic acid methyl ester is unstable in the nitration reaction process and is easy to produce side reaction, so that the yield is reduced. In addition, the introduction of a nitro group can release about 153kJ/mol of heat, and the higher the temperature is, the faster the nitration reaction rate is, and the more heat is released, so that the explosion caused by temperature runaway is extremely easy to occur. Therefore, it is highly demanded to improve the mass transfer and heat transfer capacity in the process of the nitration reaction of the methyl o-chlorophenylacetate so as to reduce the accumulation of heat in the reactor and effectively improve the safety of the nitration process.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for continuously preparing 2-chloro-5-methyl nitroacetate.
In order to achieve the above purpose, the invention adopts the following technical scheme: a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate comprising the steps of:
(a) Respectively carrying out micro-flow mixing on the o-chlorophenylacetic acid methyl ester solution and the mixed acid to carry out nitration reaction to obtain reaction liquid; the mixed acid contains nitric acid, and the molar ratio of the nitric acid to the o-chlorophenylacetic acid methyl ester is 1-1.5: 1, a step of; the flow rate of the o-chloroacetic acid methyl ester solution is larger than that of the mixed acid, the flow rate of the o-chloroacetic acid methyl ester solution is 20-65 ml/min, and the flow rate of the mixed acid is 5.0-35.0 ml/min;
(b) Separating, evaporating, concentrating, crystallizing and filtering the reaction liquid to obtain the 2-chloro-5-methyl nitrophenylacetate.
Optimally, in the step (a), the o-chlorophenylacetic acid methyl ester solution is obtained by dissolving o-chlorophenylacetic acid methyl ester in dichloroethane, wherein the mass ratio of the o-chlorophenylacetic acid methyl ester to the dichloroethane is 1: 1-4.
Further, in the step (a), the mixed acid is HNO 3 and H 2SO4 according to a mass ratio of 1: 1-5.
Optimally, in the step (a), the o-chlorophenylacetic acid methyl ester solution and the mixed acid are subjected to micro-flow mixing in a micro-channel reactor so as to carry out nitration reaction;
The microchannel reactor comprises a reaction unit and cover plates arranged at two ends of the reaction unit, wherein the reaction unit comprises a heat exchange plate, an acid phase feeding plate, a polytetrafluoroethylene microporous plate and an organic phase feeding plate which are sequentially and tightly laminated;
The acid phase feeding plate comprises an acid phase feeding plate body, a first groove micro-channel and an acid phase discharging hole, wherein the acid phase feeding hole and the acid phase discharging hole are correspondingly formed in the acid phase feeding plate body, and the first groove micro-channel is formed in the surface, facing the polytetrafluoroethylene micro-pore plate, of the acid phase feeding plate body;
The heat exchange plate comprises a heat exchange plate body, a heat exchange channel and a heat transfer oil inlet and a heat transfer oil outlet which are correspondingly arranged on the heat exchange plate body, and the heat exchange channel is at least arranged on the surface of the heat exchange plate body facing the acid phase feeding plate;
The organic phase feeding plate comprises an organic phase feeding plate body, a second groove micro-channel and an organic phase feeding hole, wherein the organic phase feeding hole is formed in the organic phase feeding plate body, and the second groove micro-channel is formed in the surface, facing the polytetrafluoroethylene micro-pore plate, of the organic phase feeding plate body; the first groove micro-channel and the second groove micro-channel independently comprise a plurality of circulation grooves with diameters of 0.5-2 mm;
The polytetrafluoroethylene micro-porous plate comprises a corrosion-resistant plate body and a plurality of micro-pores which are arranged on the corrosion-resistant plate body and are communicated with the first groove micro-channel and the second groove micro-channel; the diameter of the micropores is 100-900 mu m.
Further, the pressure at the organic phase feeding plate is larger than the pressure at the acid phase feeding plate, so that the o-chlorophenylacetic acid methyl ester solution enters the acid phase feeding plate through the micropores to carry out nitration reaction with mixed acid in the acid phase feeding plate.
Still further, sealing sheets are provided independently of each other between the heat exchange plate and the acid phase feed plate, between the acid phase feed plate and the polytetrafluoroethylene micro-porous plate, and between the polytetrafluoroethylene micro-porous plate and the organic phase feed plate.
Still further, the first groove microchannel and the second groove microchannel independently comprise a plurality of flow grooves having a diameter of 1 mm; the diameter of the micropores is 500 μm.
Further, in the step (a), the residence time of the raw material for the nitration reaction in the microchannel reactor is 4.0-35 s.
Optimally, in the step (a), the o-chlorophenylacetic acid methyl ester solution and the mixed acid are mutually and independently subjected to precooling treatment before mixing, wherein the precooling temperature is-5-30 ℃; preferably, the precooling temperature is-5-20 ℃.
Further, the method also comprises the following steps:
(c) And concentrating the lower water phase obtained by separating the liquid, recycling and applying, and recycling and applying the filtrate obtained by evaporating and concentrating the distilled solvent, crystallizing and filtering.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: according to the method for continuously preparing the 2-chloro-5-nitromethyl acetate, the nitration reaction is carried out by micro-flow mixing, so that the defect that the continuous reaction is required to be carried out for 4-5 hours in a low-temperature environment (-5 ℃) in the nitration process of the o-chlorophenylacetic methyl ester is effectively overcome, the consumption of high-level cold public engineering can be greatly reduced, and the production cost is reduced.
The micro-channel reactor with a specific structure is adopted to carry out continuous flow process, the reaction time is shortened from original 4-5 hours to 4.0-35 s, the reaction time is less than original 0.2%, the reaction time is greatly shortened, and the production efficiency is improved; meanwhile, the micro-channel reactor has small channel inner volume, small equipment occupation area and safer reaction. The nitration reaction is a strong exothermic reaction, releases a large amount of heat in a short time, and can be matched with efficient heat exchange of the microchannel reactor, so that the reaction temperature can be controlled to be carried out at 20 ℃, the proportion of other side reactions of the reaction materials in a high-temperature strong-oxidability environment for a long time can be greatly reduced, and the reaction yield, the product yield and the purity are improved.
Drawings
FIG. 1 is a schematic structural view of an apparatus for continuously producing methyl 2-chloro-5-nitrophenylacetate according to the present invention;
FIG. 2 is a schematic structural view of a microchannel reactor according to the present invention;
FIG. 3 is a schematic view of a heat exchange plate according to the present invention;
FIG. 4 is a schematic view of the structure of the acid phase feed plate of the present invention;
FIG. 5 is a schematic diagram of the structure of a polytetrafluoro-plate according to the present invention;
FIG. 6 is a schematic diagram of the structure of the organic phase feed plate of the present invention.
Detailed Description
The following detailed description of the preferred embodiments of the present invention will be provided in connection with.
Example 1
This example provides a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate which was continuously produced using the apparatus shown in FIG. 1.
The device mainly comprises an acid mixing feeding component, an organic phase feeding component, a micro-channel reactor 7, a liquid-liquid layering device 8, a first evaporator 10 and a crystallizer 11, and can realize micro-flow mixing reaction by accurately controlling the feeding amount of each raw material.
The mixed acid feeding assembly is used for conveying a mixed acid solution and comprises a mixed acid tank 1 and a first precooler 3 connected with the mixed acid tank 1 through a mixed acid conveying pump 2. Namely, a mixed acid delivery pump 2 is connected between the mixed acid tank 1 and the first precooler 3, and the first precooler 3 is connected with the microchannel reactor 7, so that the mixed acid stored in the mixed acid tank 1 is delivered downstream by the mixed acid delivery pump 2 so as to flow through the first precooler 3, and is input into the microchannel reactor 7 after being precooled. The organic phase feeding component comprises an o-chlorophenylacetic acid methyl ester solution tank 4 and a second precooler 6 connected with the o-chlorophenylacetic acid methyl ester solution tank 4 through a solution delivery pump 5. The solution delivery pump 5 is connected between the methyl o-chloroacetate solution tank 4 and the second precooler 6, and the second precooler 6 is also connected with the microchannel reactor 7, so that the solution delivery pump 5 is utilized to deliver the methyl o-chloroacetate solution stored in the solution delivery pump 5 to the downstream so as to enable the solution to flow through the second precooler 6, and the solution is input into the microchannel reactor 7 after being precooled (the first precooler 3 and the second precooler 6 cool the flowing materials to-5-30 ℃ independently).
The micro-channel reactor 7 is respectively connected with the mixed acid feeding component and the organic phase feeding component (namely respectively connected with the first precooler 3 and the second precooler 6) and is used for receiving the mixed acid solution and the o-chlorophenylacetic acid methyl ester solution and mixing and reacting the mixed acid solution and the o-chlorophenylacetic acid methyl ester solution. In this embodiment, as shown in fig. 2 to 6, the microchannel reactor 7 includes a reaction unit and cover plates 71 mounted at both ends of the reaction unit (the cover plates 71 may be mounted at both ends of the reaction unit by fasteners such as conventional bolts so that the cover plates 71 and the reaction unit are fastened together), the reaction unit includes a heat exchange plate 72, an acid phase feed plate 73, a polytetrafluoroethylene plate 74 (the polytetrafluoroethylene plate 74 may be made of other materials as required, so long as it has corrosion resistance, does not participate in the reaction, and is a preferred material) and an organic phase feed plate 75, which are stacked in this order; sealing sheets 76 are also provided independently of each other between the heat exchange plate 72 and the acid phase feed plate 73, between the acid phase feed plate 73 and the polytetrafluoroethylene micro-porous plate 74, and between the polytetrafluoroethylene micro-porous plate 74 and the organic phase feed plate 75, thereby ensuring the sealability of the entire microchannel reactor 7. Specifically, the acid phase feeding plate 73 includes an acid phase feeding plate body 731, a first groove micro-channel 732, and an acid phase feeding port 733 and an acid phase discharging port 734 correspondingly disposed on the acid phase feeding plate body 731, the first groove micro-channel 732 being opened on a surface facing the polytetrafluoroethylene micro-porous plate 74 in the acid phase feeding plate body 731; the heat exchange plate 72 includes a heat exchange plate body 721, a heat exchange channel 722, and a heat transfer oil inlet 723 and a heat transfer oil outlet 724 correspondingly disposed on the heat exchange plate body 721, wherein the heat exchange channel 722 is at least disposed on a surface of the heat exchange plate body 721 facing the acid phase feeding plate 73, for timely removing reaction heat (the heat exchange plate body 721 may also be disposed on two surfaces with the heat exchange channel 722, thereby improving heat exchange effect); the organic phase feeding plate 75 includes an organic phase feeding plate body 751, a second groove micro-channel 752, and an organic phase feeding port 753 provided on the organic phase feeding plate body 751, the second groove micro-channel 752 being opened on a surface facing the polytetrafluoroethylene micro-plate 74 in the organic phase feeding plate body 751; the polytetrafluoroethylene micro-porous plate 74 comprises a corrosion-resistant plate body and a plurality of micro-pores 741 which are arranged on the corrosion-resistant plate body and are communicated with the first groove micro-channel 732 and the second groove micro-channel 752; at this time, the feeding pressure of the organic phase is required to be slightly higher than the feeding pressure of the mixed acid, so that the o-chloroacetic acid methyl ester solution enters the acid phase feeding plate 73 through the micropores 741 of the polytetrafluoroethylene microporous plate 74 to perform nitration reaction, namely, the o-chloroacetic acid methyl ester is highly dispersed in the mixed acid, so that the mass transfer capacity between the liquid phase and the liquid phase is greatly enhanced, and the instant uniform mixing and efficient heat transfer of materials can be realized. In the microchannel reactor 7, the o-chlorophenylacetic acid methyl ester is dispersed into micro-droplets with small diameter, so that the contact area of liquid phase and liquid phase is greatly increased, and the problem that the process is controlled by mass transfer in the traditional liquid-liquid phase reaction is solved.
The micropores 741 are micron-sized, and are usually arranged in rows or columns in an array manner, and the diameter of the micropores is 100-900 μm (500 μm in the embodiment); the first groove microchannel 732 and the second groove microchannel 752 independently comprise a plurality of flow grooves (1 mm in this embodiment) having diameters of 0.5 to 2mm, and these flow grooves are usually connected in parallel (eight channels in this embodiment, and a liquid separation channel and a liquid combination channel are formed at both ends thereof, respectively) to further reduce the flow rate of the materials participating in the reaction. Specifically, the heat exchange plate 72, the acid phase feeding plate 73 and the heat exchange channels 722, the first groove micro-channels 732 and the second groove micro-channels 752 on the organic phase feeding plate 75 are in a mirror image corresponding relationship integrally, and the distribution positions of the micro-holes 741 correspond to the positions of the groove micro-channels. In operation, since the pressure in the second recessed micro-channels 752 of the organic phase feeding plate 75 is slightly higher than the pressure in the first recessed micro-channels 732 of the acid phase feeding plate 73, the organic phase can enter the first recessed micro-channels 732 of the acid phase feeding plate 73 from the second recessed micro-channels 752 of the organic phase feeding plate 75 through the micro-holes 741 of the polytetrafluoroethylene micro-holes plate 74 to be mixed and reacted.
The liquid-liquid separator 8 is connected to the microchannel reactor 7 (specifically, to the acid phase outlet 734) and is configured to receive the liquid from the microchannel reactor 7 and separate the liquid into an upper organic liquid and a lower aqueous phase. The first evaporator 10 is connected with the liquid-liquid separator 8 and is used for receiving the upper organic liquid and carrying out reduced pressure distillation on the upper organic liquid; specifically, the first evaporator 10 is connected to the liquid-liquid separator 8 through an upper organic liquid transfer pump 9, so that the upper organic liquid in the liquid-liquid separator 8 is pumped into the first evaporator 10 by the upper organic liquid transfer pump 9 for reduced pressure distillation.
The second evaporator 15 is connected with the liquid-liquid separator 8 and is used for receiving the lower water phase of the liquid-liquid separator 8 so as to dehydrate and concentrate the lower water phase; the top of the second evaporator 15 is connected with a steam water tank 17 through a steam condensing pipe 16, so that the steam evaporated by the second evaporator 15 is condensed into condensed water which is stored in the steam water tank 17 for recycling. The bottom of the second evaporator 15 is also connected with the mixed acid tank 1, so that the concentrated sulfuric acid (the concentrated solution at the bottom of the second evaporator 15) is returned to the mixed acid tank 1 (i.e. reintroduced into the mixed acid tank 1) and is applied to the process, the recycling of sulfuric acid is realized, and the waste acid emission is reduced.
The first evaporator 10 is connected to a distilled solvent tank 14 through a condenser 13, so that distilled solvent (solvent dissolving methyl o-chlorophenoacetate, preferably dichloroethane) of the first evaporator 10 is stored in liquid form in the distilled solvent tank 14 after being cooled by the condenser 13. The first evaporator 10 is also connected with a crystallizer 11, and is used for receiving the liquid out of the first evaporator 10 (the concentrated liquid of the first evaporator 10) and cooling and crystallizing the liquid (the crystallized product is 2-chloro-5-methyl nitrophenylacetate crystal); the crystallizer 11 is also connected to a filter 12 for filtering the crystallized product; the concentrated solution in the first evaporator 10 is cooled and crystallized by a crystallizer 11 to obtain 2-chloro-5-methyl nitroacetate crystals and crystallized mother liquor, and the 2-chloro-5-methyl nitroacetate solid product is obtained by filtering and washing by a filter 12. In this embodiment, the distilled solvent tank 14 and the filter 12 are also connected to the o-chlorophenylacetic acid methyl ester solution tank 4 independently of each other for guiding the distilled solvent, filtrate back to the o-chlorophenylacetic acid methyl ester solution tank 4; the solvent is distilled off, and the filtered crystallization mother liquor is returned to the o-chlorophenylacetic acid methyl ester solution tank 4 and is applied to the process, so that the recycling of the solvent dichloroethane is realized. The embodiment realizes the continuous preparation of the methyl 2-chloro-5-nitrophenylacetate and the recycling of the solvent and the sulfuric acid by using the device for continuously preparing the methyl 2-chloro-5-nitrophenylacetate, and realizes the economic, efficient and green process.
The method for continuously preparing the 2-chloro-5-nitro methyl phenylacetate comprises the following steps:
(a) The method comprises the steps of mixing an o-chloroacetic acid methyl ester solution (the o-chloroacetic acid methyl ester is dissolved in dichloroethane, the concentration of the o-chloroacetic acid methyl ester is 25 wt%), mixed acid (nitric acid (the concentration is 98 wt%) and sulfuric acid (the concentration is 98 wt%) according to a mass ratio of 1:3), and specifically comprises the following steps: taking 250 ml three-mouth bottles, preparing a mixed acid solution, adding 26 g nitric acid (the concentration is 98 wt%) to the temperature of 0-10 ℃, dropwise adding 65g sulfuric acid (the concentration is 98 wt%) after 30 minutes of dropwise adding to obtain mixed acid), respectively performing micro-flow mixing (namely respectively inputting the mixed acid into the micro-channel reactor 7 through an organic phase feeding component and an mixed acid feeding component, wherein the flow rate of the o-chloroacetic acid methyl ester solution is 24 ml/min, the flow rate of the mixed acid is 6.3ml/min, and the mole ratio of HNO 3 to the o-chloroacetic acid methyl ester is 1.1: 1) To carry out nitration reaction to obtain reaction liquid (reaction temperature is about 20 ℃ and residence time is 15.3 s; the feeding pressure of the o-chloroacetic acid methyl ester solution is slightly higher than that of the mixed acid, so that the o-chloroacetic acid methyl ester solution is highly dispersed in the mixed acid and subjected to nitration reaction in the acid phase feeding plate 73);
(b) Quenching the reaction solution (the reaction solution outputted from the microchannel reactor 7) with ice water, and standing for 10 min to form an organic phase (upper organic phase) and an aqueous phase (lower aqueous phase) for delamination; taking an upper organic phase (comprising 2-chloro-5-methyl nitroacetate), carrying out reduced pressure distillation (the conventional process), cooling and crystallizing to obtain a crude product of the 2-chloro-5-methyl nitroacetate, filtering, washing with water, and obtaining the refined 2-chloro-5-methyl nitroacetate.
The detection shows that the conversion rate of the o-chlorophenylacetic acid methyl ester is 99.7%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 89.8%, the purity is 99.5%, and the appearance is white solid.
Example 2
This example provides a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate, which is substantially identical to that of example 1, except that: in the step (a), the flow rate of the o-chlorophenylacetic acid methyl ester solution is 13 ml/min, the flow rate of the mixed acid is 3.2ml/min, the reaction temperature is about-5 ℃ and the residence time is 30.1s.
Through detection, the conversion rate of the o-chlorophenylacetic acid methyl ester is 98.5%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 85.0%, the purity is 99.1%, and the appearance is white crystals.
Example 3
This example provides a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate, which is substantially identical to that of example 1, except that: in the step (a), the flow rate of the o-chlorophenylacetic acid methyl ester solution is 63 ml/min, the flow rate of the mixed acid is 34.7ml/min, the reaction temperature is about 30 ℃ and the residence time is 4.8s.
Through detection, the conversion rate of the o-chlorophenylacetic acid methyl ester is 99.8%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 80.9%, the purity is 99.4%, and the appearance is white crystals.
Example 4
This example provides a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate, which is substantially identical to that of example 1, except that: in the step (a), the flow rate of the o-chlorophenylacetic acid methyl ester solution is 24ml/min, the flow rate of the mixed acid is 5.4ml/min, the reaction temperature is about 20 ℃ and the residence time is 15.8s.
Through detection, the conversion rate of the o-chlorophenylacetic acid methyl ester is 97.1%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 78.4%, the purity is 99.0%, and the appearance is white crystals.
Example 5
This example provides a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate, which is substantially identical to that of example 4, except that: in the step (a), nitric acid (the concentration is 98 wt%) and sulfuric acid (the concentration is 98 wt%) are mixed according to the mass ratio of 1:5, mixing; the flow rate of the o-chlorophenylacetic acid methyl ester solution is 22ml/min, and the flow rate of the mixed acid is 7.4ml/min.
Through detection, the conversion rate of the o-chlorophenylacetic acid methyl ester is 99.2%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 82.5%, the purity is 99.1%, and the appearance is white crystals.
Example 6
This example provides a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate, which is substantially identical to that of example 1, except that: in the step (a), the flow rate of the o-chloroacetic acid methyl ester solution is 24ml/min, the flow rate of the mixed acid is 5.5ml/min, and the mol ratio of HNO 3 to the o-chloroacetic acid methyl ester is 1.05:1.
Through detection, the conversion rate of the o-chlorophenylacetic acid methyl ester is 97.8%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 78.7%, the purity is 99.0%, and the appearance is white crystals.
Example 7
This example provides a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate, which is substantially identical to that of example 1, except that: in the step (a), the flow rate of the o-chloroacetic acid methyl ester solution is 24ml/min, the flow rate of the mixed acid is 6.8ml/min, and the mol ratio of HNO 3 to the o-chloroacetic acid methyl ester is 1.5: 1.
Through detection, the conversion rate of the o-chlorophenylacetic acid methyl ester is 97.8%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 84.6%, the purity is 99.2%, and the appearance is white crystals.
Example 8
This example provides a process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate, which is substantially identical to that of example 1, except that: in the step (a), the flow rate of the o-chlorophenylacetic acid methyl ester solution is 30ml/min, the flow rate of the mixed acid is 6.3ml/min, and the residence time is 13s.
Through testing, the conversion rate of the o-chlorophenylacetic acid methyl ester is 98.8%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 87.8%, the purity is 99.1%, and the appearance is white crystals.
Comparative example 1
The example provides a preparation method of 2-chloro-5-nitromethyl phenylacetate, which comprises the following steps:
taking 250 ml three-mouth bottles, preparing a mixed acid solution, adding 26 g nitric acid (the concentration is 98 wt%) to the mixed acid solution, cooling to 0-10 ℃, and dripping 65g sulfuric acid (the concentration is 98 wt%) to the mixed acid solution for 30 minutes.
Taking 500 ml three-mouth bottles, and adding 69 g o-chlorophenylacetic acid methyl ester and 208 g dichloroethane; controlling the reaction temperature to be 20 ℃, dropwise adding mixed acid, and finishing the dropwise adding for 3.5 hours; the reaction was continued for 1h at constant temperature. After the reaction is finished, quenching the reaction solution with ice water, and standing for 10 min, and then layering an organic phase and an aqueous phase; taking an organic phase containing 2-chloro-5-methyl nitroacetate, carrying out reduced pressure distillation, cooling and crystallization to obtain a crude product of the 2-chloro-5-methyl nitroacetate, filtering, and washing with water to obtain refined 2-chloro-5-methyl nitroacetate.
Through detection, the conversion rate of the o-chlorophenylacetic acid methyl ester is 99.6%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 75.8%, the purity is 99.1%, and the appearance is white crystals.
Comparative example 2
This example provides a process for the preparation of methyl 2-chloro-5-nitrophenylacetate, which is substantially identical to that of comparative example 1, except that: 69 g o-chlorophenylacetic acid methyl ester and 280 g dichloroethane are added into a 500 ml three-mouth bottle; controlling the reaction temperature to be-5 ℃, and dropwise adding mixed acid for 3.5 hours.
Through detection, the conversion rate of the o-chlorophenylacetic acid methyl ester is 99.7%, the yield of the 2-chloro-5-nitrophenylacetic acid methyl ester is 76.4%, the purity is 99.1%, and the appearance is white crystals.
As can be seen from the results of examples 1 to 8 of the present invention, the selectivity of methyl 2-chloro-5-nitrophenylacetate was higher than that of comparative examples 1 to 2 (conventional nitration reaction process, batch tank reaction). In the microchannel reactor, the liquid-liquid two phases (organic phase and acid phase) are dispersed into micro-droplets with small diameters, so that the contact area of the liquid-liquid two phases is greatly increased, the heat transfer efficiency is high, and the problem that the process is controlled by mass transfer and heat transfer in the traditional liquid-liquid two-phase nitration reaction is solved. The most selective methyl 2-chloro-5-nitrophenylacetate of example 1 is the most preferred example. Compared with example 1, examples 2-3, the reaction temperature is reduced or increased, the temperature is increased, and the reaction rate is accelerated; the temperature is too high, the selectivity is reduced, and the side reaction is increased. Examples 4-7, the dosage of sulfuric acid and nitric acid is reduced or increased, the dosage of sulfuric acid and nitric acid is increased, and the reaction rate is accelerated; the consumption of sulfuric acid and nitric acid is too high, the selectivity is reduced, and the side reaction is increased. Examples 4, 8 reduce or increase the amount of dichloroethane used during the reaction; the consumption of dichloroethane is increased, the viscosity of the system can be reduced, and the mass transfer effect is improved; the excessive dosage of dichloroethane plays a role in dilution, and reduces the concentration of reactants, thereby reducing the reaction rate.
The above embodiments are provided for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the present invention and to implement the same, but are not intended to limit the scope of the present invention, and all equivalent changes or modifications according to the spirit of the present invention should be included in the scope of the present invention.
Claims (10)
1. A process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate, comprising the steps of:
(a) Respectively carrying out micro-flow mixing on the o-chlorophenylacetic acid methyl ester solution and the mixed acid to carry out nitration reaction to obtain reaction liquid; the mixed acid contains nitric acid, and the molar ratio of the nitric acid to the o-chlorophenylacetic acid methyl ester is 1-1.5: 1, a step of; the flow rate of the o-chloroacetic acid methyl ester solution is larger than that of the mixed acid, the flow rate of the o-chloroacetic acid methyl ester solution is 20-65 ml/min, and the flow rate of the mixed acid is 5.0-35.0 ml/min;
(b) Separating, evaporating, concentrating, crystallizing and filtering the reaction liquid to obtain the 2-chloro-5-methyl nitrophenylacetate.
2. The method for continuously preparing 2-chloro-5-nitrophenylacetic acid methyl ester according to claim 1, wherein: in the step (a), the o-chlorophenylacetic acid methyl ester solution is obtained by dissolving o-chlorophenylacetic acid methyl ester in dichloroethane, wherein the mass ratio of the o-chlorophenylacetic acid methyl ester to the dichloroethane is 1: 1-4.
3. The process for continuously preparing methyl 2-chloro-5-nitrophenylacetate according to claim 1 or 2, characterized in that: in the step (a), the mixed acid is HNO 3 and H 2SO4 according to the mass ratio of 1: 1-5.
4. The method for continuously preparing 2-chloro-5-nitrophenylacetic acid methyl ester according to claim 1, wherein: in step (a), the o-chlorophenylacetic acid methyl ester solution and the mixed acid are subjected to micro-flow mixing in a micro-channel reactor (7) to carry out nitration reaction;
The microchannel reactor (7) comprises a reaction unit and cover plates (71) arranged at two ends of the reaction unit, wherein the reaction unit comprises a heat exchange plate (72), an acid phase feeding plate (73), a polytetrafluoroethylene micro-pore plate (74) and an organic phase feeding plate (75) which are sequentially and tightly laminated;
The acid phase feeding plate (73) comprises an acid phase feeding plate body (731), a first groove micro-channel (732) and an acid phase feeding port (733) and an acid phase discharging port (734) which are correspondingly arranged on the acid phase feeding plate body (731), wherein the first groove micro-channel (732) is formed in the surface, facing the polytetrafluoroethylene micro-pore plate (74), of the acid phase feeding plate body (731);
The heat exchange plate (72) comprises a heat exchange plate body (721), a heat exchange channel (722), and a heat transfer oil inlet (723) and a heat transfer oil outlet (724) which are correspondingly arranged on the heat exchange plate body (721), wherein the heat exchange channel (722) is at least arranged on the surface of the heat exchange plate body (721) facing the acid phase feeding plate (73);
The organic phase feeding plate (75) comprises an organic phase feeding plate body (751), a second groove micro-channel (752) and an organic phase feeding port (753) arranged on the organic phase feeding plate body (751), wherein the second groove micro-channel (752) is arranged on the surface, facing the polytetrafluoroethylene micro-pore plate (74), of the organic phase feeding plate body (751); the first groove micro-channel (732) and the second groove micro-channel (752) independently comprise a plurality of flow grooves with diameters of 0.5-2 mm;
the polytetrafluoroethylene micro-pore plate (74) comprises a corrosion-resistant plate body and a plurality of micro-pores (741) which are arranged on the corrosion-resistant plate body and are communicated with the first groove micro-channel (732) and the second groove micro-channel (752); the diameter of the micropores (741) is 100-900 mu m.
5. The method for continuously preparing 2-chloro-5-nitrophenylacetic acid methyl ester according to claim 4, wherein: the pressure of the organic phase feeding plate (75) is larger than that of the acid phase feeding plate (73), so that the o-chlorophenylacetic acid methyl ester solution enters the acid phase feeding plate (73) through the micropores (741) to carry out nitration reaction with mixed acid in the acid phase feeding plate.
6. The process for continuously preparing methyl 2-chloro-5-nitrophenylacetate according to claim 4 or 5, wherein: sealing thin plates (76) are arranged between the heat exchange plate (72) and the acid phase feeding plate (73), between the acid phase feeding plate (73) and the polytetrafluoroethylene micro-pore plate (74) and between the polytetrafluoroethylene micro-pore plate (74) and the organic phase feeding plate (75) independently of each other.
7. The process for continuously preparing methyl 2-chloro-5-nitrophenylacetate according to claim 4 or 5, wherein: the first groove microchannel (732) and the second groove microchannel (752) independently comprise a plurality of flow-through grooves having a diameter of 1 mm; the diameter of the micropores (741) is 500 μm.
8. The process for continuously preparing methyl 2-chloro-5-nitrophenylacetate according to claim 4 or 5, wherein: in the step (a), the residence time of the nitrifying raw material in the microchannel reactor (7) is 4.0-35 s.
9. The method for continuously preparing 2-chloro-5-nitrophenylacetic acid methyl ester according to claim 1, wherein: in the step (a), the o-chlorophenylacetic acid methyl ester solution and the mixed acid are mutually and independently subjected to precooling treatment before mixing, and the precooling temperature is-5-30 ℃.
10. The process for the continuous preparation of methyl 2-chloro-5-nitrophenylacetate according to claim 1 or 9, further comprising the steps of:
(c) And concentrating the lower water phase obtained by separating the liquid, recycling and applying, and recycling and applying the filtrate obtained by evaporating and concentrating the distilled solvent, crystallizing and filtering.
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