CN112300033B - Device and method for fully continuously synthesizing 2-nitro-4-methylsulfonyl benzoic acid from 4-methylsulfonyl toluene - Google Patents
Device and method for fully continuously synthesizing 2-nitro-4-methylsulfonyl benzoic acid from 4-methylsulfonyl toluene Download PDFInfo
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Abstract
The invention discloses a device for fully continuously synthesizing 2-nitro-4-methylsulfonyl benzoic acid from 4-methylsulfonyl toluene, which comprises a first storage tank, a second storage tank, a first metering pump, a second metering pump, a first tubular reactor, a second tubular reactor and a collecting kettle. The invention also discloses a method for synthesizing 2-nitro-4-methylsulfonyl benzoic acid by adopting a tubular reaction mode based on the device. The device design and the device-based method realize the synthesis of the target product by adopting a tubular reaction mode, and solve the technical defects of difficult recovery and large pollution of the existing kettle type preparation waste acid.
Description
Technical Field
The invention relates to the field of 2-nitro-4-methylsulfonyl benzoic acid synthesis devices, in particular to a device and a method for fully continuously synthesizing 2-nitro-4-methylsulfonyl benzoic acid from 4-methylsulfonyl toluene.
Background
2-nitro-4-methylsulfonylbenzoic acid (NMSBA) is an important organic synthesis intermediate, mainly used for synthesizing herbicide mesotrione. Because of the advantages of wide grass-killing spectrum, good grass-killing effect, small damage to aftercrop, safe use and the like, the mesotrione is widely used, stably occupies the market of corn field herbicides, can be mixed with other herbicides for use, and has increased market demands year by year. The existing process for synthesizing 2-nitro-4-methylsulfonyl benzoic acid is mainly prepared by taking 4-methylsulfonyl toluene as a raw material and performing two-step reactions of nitration and oxidation.
Synthesis reaction formula of 2-nitro-4-methylsulfonyl benzoic acid
At present, kettle type reaction is mostly adopted for preparing 2-nitro-4-methylsulfonyl benzoic acid by the reaction, and the kettle type reaction has the defects that a large amount of concentrated sulfuric acid is needed, and the concentrated sulfuric acid cannot be recycled, so that the amount of wastewater is large in the industrial preparation process.
In the synthesis method of 2-nitro-4-methylsulfonyl benzoic acid disclosed in the prior art, the nitration reaction mainly uses p-methylsulfonyl toluene, sulfuric acid and nitric acid as raw materials, and the original kettle type process is transformed into a continuous flow process. For example, the Chinese patent application number is: CN110845373A, CN110759837a and CN110305047a disclose synthetic methods for 2-nitro-4-methylsulfonyl toluene.
In the methods reported in the above patent documents, 4-methylsulfonyl toluene is usually dissolved in sulfuric acid, and mixed with a nitric acid-sulfuric acid solution, followed by continuous transfer to a continuous flow reactor for reaction. The reaction process generates a large amount of sulfuric acid waste acid, and the sulfuric acid waste acid can be recycled and reused, so that on one hand, the post-treatment process is increased, and on the other hand, the sulfuric acid waste acid is recycled and reused for multiple times, the impurity accumulation is carried out, and the product quality is reduced.
The Chinese patent application number is: CN1995014 reports "a method for preparing 2-nitro-4-methylsulfonyl toluene with a solid superacid catalyst", wherein 4-methylsulfonyl toluene is used as a raw material, the solid superacid is used as a catalyst, and acetic anhydride is used for replacing sulfuric acid.
In the technical scheme disclosed in the patent, although the use of sulfuric acid is avoided, 4-methylsulfonyl toluene is dissolved by adopting an organic solvent, acetic anhydride and the organic solvent are required to be separated after the reaction is finished, and the catalyst also needs to be further treated for application.
The synthesis modes of 2-nitro-4-methylsulfonyl benzoic acid are various, such as a cyano hydrolysis method and an oxidation method, but a cyano hydrolysis method substrate is extremely toxic and expensive, and is not suitable for industrial production, and the common synthesis method is an oxidation method at present, wherein 2-nitro-4-methylsulfonyl toluene is taken as a raw material, and an oxidant is used for oxidizing methyl on an aromatic ring into carboxyl to prepare 2-nitro-4-methylsulfonyl benzoic acid.
However, the aromatic ring of the 2-nitro-4-methylsulfonyl toluene is connected with two strong electron withdrawing groups, so that the oxidation of methyl on the aromatic ring becomes difficult, and a stronger oxidant and a catalyst are needed to accelerate the reaction. There are various oxidation modes reported at present.
The stoichiometric oxidation is carried out, the oxidant is high-valence metal salts such as potassium dichromate and the like, and the oxidation capability is strong. For example, the Chinese patent application number is: CN201610778084 discloses a method for oxidizing potassium dichromate. However, the method has mild and simple operation conditions and higher yield, but can produce heavy metal pollution and is not friendly to the environment.
Hydrogen peroxide catalytic oxidation, strong hydrogen peroxide oxidizing ability and accords with the green chemical idea. The Chinese patent application number is: patent CN102584650A, CN10153383A and other patents report that the process uses hydrogen peroxide as an oxidant to oxidize 2-nitro-4-methylsulfonyl toluene in sulfuric acid, but the high yield of 2-nitro-4-methylsulfonyl benzoic acid is realized, the hydrogen peroxide consumption is large, and the production cost is high.
The molecular oxygen is used as an oxidant for catalytic oxidation, and the cost is low and the environment is protected. However, the oxygen molecules are in the ground state at normal temperature, the oxidation activity is not high enough, and the addition of a catalyst and the enhancement of reaction conditions are generally required. The Chinese patent application number is: CN106496079A, CN103787934a reports a multi-element catalytic system consisting of heteropolyacid-metal oxide-halogen. The Chinese patent application number is: CN108530326a reports a catalytic oxidation system for N-hydroxylamine compounds. US patent 5591890 reports a catalytic oxidation system with cobalt acetate as catalyst. However, the methods have the defects of complicated catalyst preparation and recovery, long reaction time, low safety and the like due to the adoption of a kettle type high-pressure system.
The nitric acid is catalyzed and oxidized, the nitric acid is cheap and easy to obtain, the oxidizing ability is strong, and the method is adopted in the current industrialized mass production. As in the prior art, see in particular: green synthesis studies of 2-nitro-4-methylsulfonylbenzoic acid, university of lehuqin, zhejiang university of industry report, 2009,37 (3): 267-271 the process uses nitric acid as oxidant, vanadium pentoxide as catalyst and concentrated sulfuric acid as solvent. Although the sulfuric acid can realize higher reaction temperature, a large amount of waste acid is generated by post-reaction treatment, the application is difficult, and the use of the high-concentration sulfuric acid can easily generate dinitration side reaction in the reaction process, so that the reaction time is long and the reaction efficiency is low due to the dropwise addition of nitric acid. And kettle type operation is adopted, so that the safety is low.
As in the prior art, see in particular: the research on the process for preparing 2-nitro-4-methylsulfonyl benzoic acid by gas-liquid oxidation by combining a plurality of processes, liu Hu, anhui chemical industry, 2013,39 (04): 48-50. The combination of nitric acid oxidation and molecular oxygen oxidation. However, the disadvantages of the nitric acid oxidation process are not addressed.
Disclosure of Invention
The invention aims to provide a device and a method for fully continuously synthesizing 2-nitro-4-methylsulfonyl benzoic acid from 4-methylsulfonyl toluene.
The conception of the invention is as follows:
the results of the kinetics study on the nitration show that the 4-methylsulfonyl benzoic acid can realize rapid nitration under mild conditions under the catalysis of concentrated sulfuric acid, and the substrate nitration is easy to carry out and has low activation energy. The nitration reaction of aromatic hydrocarbon is influenced by the concentration of sulfuric acid and the reaction temperature, when the concentration of sulfuric acid is consistent, the higher the temperature is, the more easy the nitration is, and under the condition of a certain temperature, the higher the concentration of sulfuric acid is, the stronger the nitration capability of the system is. Nitric acid has a strong nitration capacity, especially when the concentration of nitric acid is high. However, at high temperatures, the oxidizing nature of nitric acid tends to be more pronounced. The flow chemistry technology can realize the accurate control of the reaction conditions, and can realize the nitrification reaction and inhibit the oxidation reaction simultaneously by controlling the temperature of the nitrification reaction in a sectionalized and accurate way and adjusting the concentration of nitric acid. The research on the oxidation of the nitric acid-sulfuric acid mixed acid shows that nitric acid is easy to be heated and decomposed or boiled in the reaction process and is separated from a reaction system, so that the oxidation performance is reduced and the waste of nitric acid is caused, and meanwhile, the high-concentration sulfuric acid in the system enables the protonation of nitric acid to be serious, so that the improvement of the nitrification capability and the reduction of the oxidation capability are reflected. The method can avoid the protonation of nitric acid after the sulfuric acid is removed, and simultaneously adopts a fluidization technology to pressurize and strengthen the reaction process, and the nitric acid can be used under the temperature condition that the normal pressure is higher than the boiling point. Nitric acid is not easy to separate from the reaction system. The addition of molecular oxygen and the heating of nitric acid produce free radicals, which can catalyze the molecular oxygen in the ground state into high-activity oxygen free radicals well, thereby reducing the consumption of nitric acid.
The invention solves the technical problems through the following technical scheme:
the device for fully continuously synthesizing the 2-nitro-4-methylsulfonyl benzoic acid from the 4-methylsulfonyl toluene comprises a first storage tank, a second storage tank, a first metering pump, a second metering pump, a first tubular reactor, a second tubular reactor and a collecting kettle;
the liquid outlet end of the first storage tank is connected with the liquid inlet end of the first metering pump;
the liquid outlet end of the first metering pump is connected with the liquid inlet end of the first tubular reactor;
the liquid outlet end of the first tubular reactor is communicated with a three-way mixer, and the three-way mixer is provided with a first liquid inlet end, a second liquid inlet end and a liquid outlet end;
the liquid outlet end of the first tubular reactor is communicated with the first liquid inlet end of the three-way mixer, and the liquid outlet end of the second metering pump is communicated with the second liquid inlet end of the three-way mixer;
the liquid outlet end of the three-way mixer is communicated with the liquid inlet end of the second tubular reactor;
the liquid outlet end of the second tubular reactor is communicated with the liquid inlet end of the collecting kettle;
the device for fully continuously synthesizing the 2-nitro-4-methylsulfonyl benzoic acid from the 4-methylsulfonyl toluene further comprises an exhaust gas absorption kettle which is communicated with the collecting kettle.
Preferably, the liquid outlet end of the first storage tank is communicated with a first metering pump through a first pipeline;
the liquid outlet end of the first tubular reactor is communicated with the liquid inlet end of the second tubular reactor through a second pipeline;
the liquid outlet end of the second tubular reactor is communicated with the collecting kettle through a third pipeline;
the liquid outlet end of the second storage tank is communicated with the liquid inlet end of the three-way mixer through a fourth pipeline;
the top of the collecting kettle is communicated with the air inlet end of the waste gas absorbing kettle through an exhaust pipeline.
Preferably, the first tubular reactor is provided with a plurality of thermometers;
the third pipeline is provided with a back pressure valve.
Preferably, the device for fully continuously synthesizing the 2-nitro-4-methylsulfonyl benzoic acid by using the 4-methylsulfonyl toluene further comprises an oxygen supply component communicated with the fourth pipeline;
oxygen is pumped into the fourth pipeline through the oxygen supply component, and enters the second tubular reactor through the three-way mixer.
Preferably, the oxygen supply part comprises an oxygen supply tank, the air outlet end of the oxygen supply tank is communicated with a fifth pipeline, a gas flow controller is arranged on the fifth pipeline, the gas flow controller is communicated with a gas buffer tank, the air outlet end of the gas buffer tank is communicated with a sixth pipeline, and the sixth pipeline is communicated with a fourth pipeline.
Preferably, a gas pressure regulating valve is arranged between the oxygen supply tank and the gas flow controller;
and a one-way valve is arranged between the air outlet end of the sixth pipeline and the fourth pipeline.
The invention also discloses a method for synthesizing 2-nitro-4-methylsulfonyl benzoic acid based on the device, which comprises the following steps:
(1) Dissolving 4-methylsulfonyl toluene and nitric acid to prepare a reaction feed liquid, placing the reaction feed liquid in a first storage tank, dissolving a catalyst in nitric acid, and placing the catalyst in a second storage tank;
(2) Controlling the reaction temperature of the first tubular reactor to be 70-135 ℃, controlling the reaction temperature of the second tubular reactor to be 120-175 ℃ and controlling the internal pressure of the first tubular reactor and the second tubular reactor to be 0.4-4.5MPa;
(3) Pumping the material in the first storage tank into a first tubular reactor for reaction for 1-30min, discharging the material in the first tubular reactor after the reaction is finished, discharging the material in the second storage tank, mixing with the material discharged in the first tubular reactor, and pumping into a second tubular reactor for oxidation reaction for 20-300min;
(4) After the oxidation reaction is finished, pumping the materials into a collecting kettle, recovering nitric acid by reduced pressure distillation in the collecting kettle, and regulating the residual acidic materials to be alkaline by adopting a sodium hydroxide solution;
and (3) filtering after fully stirring to remove the completely unreacted nitrified product, regulating the pH value of the filtrate to be acidic, separating out the product at the moment, filtering and drying to obtain the product, and supplementing the unreacted nitrified product into the first or second storage tank for continuous use.
Preferably, the catalyst is one or a mixture of any two or more of a vanadium reagent, a copper reagent, a zirconium reagent and an N-hydroxylamine reagent.
Preferably, the vanadium reagent is any one of vanadium pentoxide, vanadium nitrate, metavanadate and ammonium metavanadate;
the copper reagent is any one of copper nitrate, copper oxide, copper acetate and copper chloride;
the zirconium reagent is any one of zirconium nitrate, zirconium chloride and zirconium acetate;
the N-hydroxylamine reagent is any one of N-hydroxyphthalimide, N '-dihydroxyphthalimide and N, N' -trihydroxyisocyanuric acid.
Preferably, the molar ratio of 4-methylsulfonyl toluene dissolution to nitric acid in the step (1) is 1.5-20:1;
the molar ratio of nitric acid to 4-methylsulfonyl toluene in the material discharged from the second storage tank in the step (3) is 1.5-25:1;
the mass ratio of the 4-methylsulfonyl toluene to the catalyst is 20-2000:1;
the concentration of nitric acid in the first storage tank is 40-95%, and the concentration of nitric acid in the second storage tank is 50-98%.
Preferably, the first tubular reactor and the second tubular reactor are made of any one of a tetrafluoro-lined stainless steel metal tube, a steel wire-lined tetrafluoro hose, a zirconium tube, a tantalum tube and the like;
the length of the first tubular reactor is 0.5-30m, and the length of the second tubular reactor is 5-100m. The first tubular reactor and the second tubular reactor adopt oil bath or externally-added jackets for heat exchange.
Compared with the prior art, the invention has the following advantages:
the invention discloses a device for fully continuously synthesizing 2-nitro-4-methylsulfonyl benzoic acid from 4-methylsulfonyl toluene, which comprises a first storage tank, a second storage tank, a first metering pump, a second metering pump, a first tubular reactor, a second tubular reactor and a collecting kettle.
1. The use of sulfuric acid is avoided.
2. Nitric acid and unreacted 2-nitro-4-methylsulfonyl toluene can be conveniently recycled, and the process is more environment-friendly.
3. The nitration reaction product does not need separation and purification, so that the reaction procedures are reduced, and the reaction cost is reduced.
4. Continuous production, accurate control of reaction parameters and small reaction amplification effect. The safety and the efficiency are effectively improved.
Provides a device which can be used for fully continuously synthesizing 2-nitro-4-methylsulfonyl benzoic acid from 4-methylsulfonyl toluene, and replaces the traditional kettle type synthesis device.
Drawings
FIG. 1 is a schematic overall structure of an embodiment of the present invention;
FIG. 2 is a schematic view showing the structure of an oxygen supplying member in the embodiment of the present invention;
FIG. 3 is a nuclear magnetic spectrum of 2-nitro-4-methylsulfonyl toluene synthesized and prepared by a first tubular reactor in example 4 of the present invention;
FIG. 4 is a nuclear magnetic spectrum of 2-nitro-4-methylsulfonyl benzoic acid synthesized and prepared by a second tubular reactor in example 4 of the present invention;
FIG. 5 is a liquid phase diagram of the material solution after the end of the reaction in the second tubular reactor in example 4 of the present invention.
FIG. 6 is a liquid phase diagram of the material solution after the end of the reaction in the first tubular reactor in example 4 of the present invention.
Detailed Description
The following describes in detail the examples of the present invention, which are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of protection of the present invention is not limited to the following examples.
EXAMPLE 1 4-device for full-continuous synthesis of 2-nitro-4-methylsulfonylbenzoic acid from methylsulfonylmethylbenzene
1-2, a device for fully continuously synthesizing 2-nitro-4-methylsulfonyl benzoic acid from 4-methylsulfonyl toluene comprises a first storage tank 1, a second storage tank 2, a first metering pump 111, a second metering pump 211, a first tubular reactor 3, a second tubular reactor 4 and a collecting kettle 6; the liquid outlet end of the first storage tank 1 is connected with the liquid inlet end of the first metering pump 111; the liquid outlet end of the first metering pump 111 is connected with the liquid inlet end of the first tubular reactor 3; the liquid outlet end of the first tubular reactor 3 is communicated with a three-way mixer a.
The three-way mixer a is provided with a first liquid inlet end, a second liquid inlet end and a liquid outlet end; the liquid outlet end of the first tubular reactor 3 is communicated with the first liquid inlet end of the three-way mixer a, and the liquid outlet end of the second metering pump 211 is communicated with the second liquid inlet end of the three-way mixer a; the liquid outlet end of the three-way mixer a is communicated with the liquid inlet end of the second tubular reactor 4.
The liquid outlet end of the second tubular reactor 4 is communicated with the liquid inlet end of the collecting kettle 6; the device also comprises an exhaust gas absorption kettle 7 communicated with the collecting kettle 6.
Specifically, the liquid outlet end of the first storage tank 1 is communicated with a first metering pump 111 through a first pipeline 11; the liquid outlet end of the first pipeline 11 is communicated with a first metering pump 111;
the liquid outlet end of the first tubular reactor 3 is communicated with the liquid inlet end of the second tubular reactor through a second pipeline 32; the liquid outlet end of the second tubular reactor 4 is communicated with a collecting kettle 6 through a third pipeline; the liquid outlet end of the second storage tank 2 is communicated with the liquid inlet end of the three-way mixer a through a fourth pipeline 21; the top of the collecting kettle 6 is communicated with the air inlet end of the waste gas absorbing kettle 7 through an exhaust pipeline.
In order to control the reaction temperature, the first tubular reactor 3 is provided with a plurality of thermometers 31; the third pipe is equipped with a back pressure valve and the second pipe reactor 4 is equipped with a temperature metering device.
In practical work, it was found that the entire reaction, if a gas having oxidizing property is introduced, can improve the reaction effect, and therefore, the following design was performed:
the device for fully continuously synthesizing the 2-nitro-4-methylsulfonyl benzoic acid by using the 4-methylsulfonyl toluene also comprises an oxygen supply component communicated with the fourth pipeline 21;
oxygen is pumped into the fourth pipe 21 through the oxygen supply means, and the oxygen enters the second pipe reactor 4 through the three-way mixer a.
Specifically, the oxygen supply part includes oxygen supply tank 8, the end intercommunication of giving vent to anger of oxygen supply tank 8 has the fifth pipeline, be equipped with gas flow controller 11 on the fifth pipeline, gas flow controller 11 communicates has gas buffer tank 9, the end intercommunication of giving vent to anger of gas buffer tank 9 has the sixth pipeline, the sixth pipeline communicates fourth pipeline 21.
An air pressure regulating valve 12 is arranged between the oxygen supply tank 8 and the air flow controller, and the air pressure of the pumped oxygen is regulated through the air pressure regulating valve 12.
A check valve 10 is arranged between the air outlet end of the sixth pipeline and the fourth pipeline 21, and the material is prevented from flowing back through the check valve 10.
In the actual working process, in order to increase the contact between oxygen and materials, baffles or fillers are assembled in the second tubular reactor 4 according to the conventional mode; the baffle plate filler is used for guiding the reaction materials and promoting the mixing of gas and liquid phases, in particular to the oxygen of the reaction materials.
The method is applied to the reaction process, and comprises the following steps:
the reaction material 4-methylsulfonyl toluene is dissolved in nitric acid solution and is placed in a first storage tank 1, the catalyst used for reaction is dissolved in nitric acid with concentration and is placed in a second storage tank 2, and the temperature settings of a first tubular reactor 3 and a second tubular reactor 4 are set. The flow rate of the first metering pump 111 is regulated to be equal to that of the second metering pump 211, and the materials enter the first tubular reactor 3 and the second tubular reactor 4 for reaction.
The material solution enters into a collecting kettle 6 for collection, and the waste gas generated in the collecting process enters into a waste gas absorption kettle 7 for recovery treatment.
The device component design realizes the synthesis of the 2-nitro-4-methylsulfonyl benzoic acid by adopting a tubular reaction mode, and solves the technical defect that the preparation of the 2-nitro-4-methylsulfonyl benzoic acid only adopts a kettle reaction disclosed in the prior art.
Example 22 Synthesis of nitro-4-methylsulfonylbenzoic acid
The synthesis steps of the 2-nitro-4-methylsulfonyl benzoic acid are as follows:
as shown in FIGS. 1-2, 170g of 4-methylsulfonyl toluene was dissolved in 405g of a 78% strength nitric acid solution and placed in a first tank 1, 0.5g of vanadium pentoxide, 3.4g of THICA was dissolved in 1115g of 85% strength nitric acid and placed in a second tank 2. The first tubular reactor 3 is evenly divided into three sections for temperature control, wherein the first section is 85 ℃, the second section is 100 ℃, and the third section is 130 ℃. The temperature of the second tubular reactor 4 was set at 150 ℃. The flow rate of the first metering pump is 2mL/min, and the flow rate of the second metering pump is 8mL/min. The pressure was 1.2MPa. The residence time of the first tubular reactor 3 is 15min (after the reaction is finished, the nuclear magnetic detection is carried out after sampling and purification, the nuclear magnetic detection result is shown in figure 3), the reaction liquid flowing out of the first tubular reactor is mixed with the feed liquid conveyed by the second metering pump in a T-shaped mixer without treatment, and then the mixture enters the second tubular reactor 4 for residence time of 50min (after the reaction is finished, the nuclear magnetic detection is carried out after sampling and purification, and the nuclear magnetic detection result is shown in figure 4).
The product in the collecting kettle 6 is decompressed and steamed into paste. The pasty product is regulated to be alkaline by a sodium hydroxide solution under the condition of full stirring, stirring is continued for 20min, then filtering is carried out, the filtrate is yellow, hydrochloric acid is added dropwise into the filtrate or dilute nitric acid recovered after distillation is added until the filtrate is acidic, a large amount of light yellow solid is precipitated at the moment, 192g of light yellow solid is obtained after drying, the single pass yield is 78%, and the purity is 99%. The filter cake after alkali washing was slurried with a small amount of 65% nitric acid and filtered to give 46g of a white solid as unreacted 2-nitro-4-methylsulfonyl toluene.
Sampling liquid phase detection is carried out at the outlet of the first tubular reactor 3, and the nitration yield of the 4-methylsulfonyl toluene is 99%.
Example 32 Synthesis of nitro-4-methylsulfonylbenzoic acid
As shown in fig. 1-2, the present example synthesizes 2-nitro-4-methylsulfonyl benzoic acid based on the device disclosed in example 1, and comprises the following specific steps:
170g of 4-methylsulfonyl toluene was dissolved in 540g of a 70% strength nitric acid solution and placed in a first tank 1, 0.5g of vanadium pentoxide, 1.0g of zirconium acetate was dissolved in 1260g of 90% strength nitric acid and placed in a second tank 2. The first tubular reactor 3 is evenly divided into two sections for temperature control, wherein the first section is 120 ℃ and the second section is 130 ℃. The temperature of the second tubular reactor 4 was set at 160 ℃. The flow rate of the first metering pump is 2mL/min, and the flow rate of the second metering pump is 6.3mL/min. The pressure was 1.5MPa.
The residence time of the first tubular reactor 3 was 12min and the residence time of the second tubular reactor 4 was 80min. The product in the collecting kettle 6 is decompressed and steamed into paste. The pasty product is regulated to be alkaline by a sodium hydroxide solution under the condition of full stirring, stirring is continued for 20min, then filtering is carried out, the filtrate is yellow, hydrochloric acid is added dropwise into the filtrate or dilute nitric acid recovered after distillation is added until the filtrate is acidic, a large amount of light yellow solid is precipitated at the moment, 233g of earthy yellow solid is obtained after drying, and the single pass yield is 95% and the purity is 98%.
The filter cake after alkali washing was slurried with a small amount of 65% nitric acid, washed and filtered to give 10g of a white solid as unreacted 2-nitro-4-methylsulfonyl toluene. Sampling liquid phase detection is carried out at the outlet of the first tubular reactor 3, and the nitration yield of the 4-methylsulfonyl toluene is 99%.
Example 4 2 Synthesis of nitro-4-methylsulfonylbenzoic acid
As shown in fig. 1-2, the present example synthesizes 2-nitro-4-methylsulfonyl benzoic acid based on the device disclosed in example 1, and comprises the following specific steps:
170g of 4-methylsulfonyl toluene was dissolved in 405g of a 78% strength nitric acid solution and placed in a first tank 1, 0.5g of vanadium pentoxide, 1.0g of copper nitrate was dissolved in 760g of a 90% strength nitric acid solution and placed in a second tank 2. The first tubular reactor 3 is evenly divided into two sections for temperature control, wherein the first section is 120 ℃ and the second section is 130 ℃. The temperature of the second tubular reactor 4 was set at 160 ℃. The flow rate of the first metering pump is 2mL/min, the flow rate of the second metering pump is 5mL/min, and the flow rate of oxygen is 20sccm. The pressure was 1.8MPa. The residence time of the first tubular reactor 3 is 12min, and the reaction liquid flowing out of the first tubular reactor is directly mixed with the oxygen and the feed liquid conveyed by the second metering pump in a cross-shaped mixer without post-treatment to form uniform gas-liquid mixed flow, and then flows into the second tubular reactor. The residence time in the second tubular reactor 4 was 60 minutes (after the completion of the reaction, the results of the sampling detection are shown in FIG. 5, and the results of the nuclear magnetic resonance detection after purifying the reaction solution are shown in FIG. 2). The product in the collecting kettle 6 is decompressed and steamed into paste. The pasty product is regulated to be alkaline by a sodium hydroxide solution under the condition of full stirring, stirring is continued for 20min, then filtering is carried out, the filtrate is yellow, hydrochloric acid is added dropwise into the filtrate or dilute nitric acid recovered after distillation is added until the filtrate is acidic, a large amount of light yellow solid is precipitated at the moment, and 240g of yellow solid is obtained after drying, wherein the single pass yield is 98%, and the purity is 99%. The filter cake after alkali washing was slurried with a small amount of 65% nitric acid, washed and filtered to give 2.5g of a white solid as unreacted 2-nitro-4-methylsulfonyl toluene. Liquid phase detection (the detection result is shown in fig. 6, nuclear magnetic detection is carried out after the reaction liquid is purified, the result is shown in fig. 1) is sampled at the outlet of the first tubular reactor 3, and the nitrification yield of 4-methylsulfonyl toluene is 99%.
Example 5 2 Synthesis of nitro-4-methylsulfonylbenzoic acid
As shown in fig. 1-2, the present example synthesizes 2-nitro-4-methylsulfonyl benzoic acid based on the device disclosed in example 1, and comprises the following specific steps:
145g of 4-methylsulfonyl toluene was dissolved in 335g of 80% strength nitric acid solution and placed in the first tank 1, 25g of recovered unreacted 2-nitro-4-methylsulfonyl toluene, 0.5g of vanadium pentoxide, 3.0g of THICA was dissolved in 1260g of 80% strength nitric acid and placed in the second tank 2. The first tubular reactor 3 is evenly divided into two sections for temperature control, wherein the first section is 115 ℃ and the second section is 132 ℃. The temperature of the second tubular reactor 4 was set at 155 ℃.
The flow rate of the first metering pump is 2mL/min, and the flow rate of the second metering pump is 7mL/min. The pressure was 1.5MPa. The residence time of the first tubular reactor 3 was 15min and the residence time of the second tubular reactor 4 was 80min. The product in the collecting kettle 6 is decompressed and steamed into paste. The pasty product is regulated to be alkaline by a sodium hydroxide solution under the condition of full stirring, stirring is continued for 20min, then filtering is carried out, the filtrate is yellow, hydrochloric acid is added dropwise into the filtrate or dilute nitric acid recovered after distillation is added until the filtrate is acidic, a large amount of light yellow solid is precipitated at the moment, 221g of earthy yellow solid is obtained after drying, and the single pass yield is 90% and the purity is 98%.
The filter cake after alkali washing was slurried with a small amount of 65% nitric acid and filtered to give 20g of a white solid as unreacted 2-nitro-4-methylsulfonyl toluene. Sampling liquid phase detection is carried out at the outlet of the first tubular reactor 3, and the nitration yield of the 4-methylsulfonyl toluene is 99%.
Example 6 2 Synthesis of nitro-4-methylsulfonylbenzoic acid
As shown in fig. 1-2, the present example synthesizes 2-nitro-4-methylsulfonyl benzoic acid based on the device disclosed in example 1, and comprises the following specific steps:
170g of 4-methylsulfonyl toluene was dissolved in 540g of a 70% strength nitric acid solution and placed in a first tank 1, 0.5g of vanadium pentoxide, 1.0g of copper nitrate, 2.5g of THICA was dissolved in 1260g of 90% strength nitric acid and placed in a second tank 2. The first tubular reactor 3 is evenly divided into two sections for temperature control, wherein the first section is 120 ℃ and the second section is 130 ℃. The temperature of the second tubular reactor 4 was set at 160 ℃. The flow rate of the first metering pump is 4mL/min, and the flow rate of the second metering pump is 8.5mL/min. The pressure was 1.5MPa. The residence time of the first tubular reactor 3 was 12min and the residence time of the second tubular reactor 4 was 60min. The product in the collecting kettle 6 is decompressed and steamed into paste. The pasty product is regulated to be alkaline by a sodium hydroxide solution under the condition of full stirring, stirring is continued for 20min, then filtering is carried out, the filtrate is yellow, hydrochloric acid is added dropwise into the filtrate or dilute nitric acid recovered after distillation is added until the filtrate is acidic, a large amount of light yellow solid is precipitated at the moment, and 211g of earthy yellow solid is obtained after drying, wherein the single pass yield is 86%, and the purity is 99%. The filter cake after alkali washing was slurried with a small amount of 65% nitric acid, washed and filtered to give 10g of a white solid as unreacted 2-nitro-4-methylsulfonyl toluene. Sampling liquid phase detection is carried out at the outlet of the first tubular reactor 3, and the nitration yield of the 4-methylsulfonyl toluene is 99%.
Through complete reaction tracking and mass analysis, a small amount of products are completely decomposed in the oxidation stage. So that the recovered 2-nitro-4-methylsulfonyl toluene is less than the theoretical value.
Example 7 comparison to the prior art
The Chinese patent application number is as follows: CN104557639a discloses a process as comparative example 1; the Chinese patent application number is as follows: CN104803815a discloses a process as comparative example 2; comparative example 3 was prepared by the technical method reported in the prior literature; the process disclosed by the specific embodiment of the invention is taken as an experimental example, and the comparison result is shown in table 1:
TABLE 1
As can be seen from the data disclosed in Table 1, compared with the existing process, the industrial method disclosed by the invention has the advantages that the reaction time is greatly reduced under the condition that the yield is basically the same, and the recycling is convenient to operate and the cost is lower although the use amount of nitric acid is increased after the use of sulfuric acid is abandoned.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (6)
1. The method for synthesizing 2-nitro-4-methylsulfonylbenzoic acid is characterized by comprising a device for fully continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonylboluene, wherein the device for fully continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonylboluene comprises a first storage tank, a second storage tank, a first metering pump, a second metering pump, a first tubular reactor, a second tubular reactor and a collecting kettle;
the liquid outlet end of the first storage tank is connected with the liquid inlet end of the first metering pump;
the liquid outlet end of the first metering pump is connected with the liquid inlet end of the first tubular reactor;
the liquid outlet end of the first tubular reactor is communicated with a three-way mixer, and the three-way mixer is provided with a first liquid inlet end, a second liquid inlet end and a liquid outlet end;
the liquid outlet end of the first tubular reactor is communicated with the first liquid inlet end of the three-way mixer, and the liquid outlet end of the second metering pump is communicated with the second liquid inlet end of the three-way mixer;
the liquid outlet end of the three-way mixer is communicated with the liquid inlet end of the second tubular reactor;
the liquid outlet end of the second tubular reactor is communicated with the liquid inlet end of the collecting kettle;
the device for fully continuously synthesizing the 2-nitro-4-methylsulfonyl benzoic acid from the 4-methylsulfonyl toluene also comprises an exhaust gas absorption kettle which is communicated with the collecting kettle;
the method for synthesizing the 2-nitro-4-methylsulfonyl benzoic acid comprises the following steps of:
(1) Dissolving 4-methylsulfonyl toluene and nitric acid to prepare a reaction feed liquid, placing the reaction feed liquid in a first storage tank, dissolving a catalyst in nitric acid, and placing the catalyst in a second storage tank;
(2) Controlling the reaction temperature of the first tubular reactor to be 70-135 ℃, controlling the reaction temperature of the second tubular reactor to be 120-175 ℃ and controlling the internal pressure of the first tubular reactor and the second tubular reactor to be 0.4-4.5MPa;
(3) Pumping the material in the first storage tank into a first tubular reactor for reaction for 1-30min, discharging the material in the first tubular reactor after the reaction is finished, discharging the material in the second storage tank, mixing with the material discharged in the first tubular reactor, and pumping into a second tubular reactor for oxidation reaction for 20-300min;
(4) After the oxidation reaction is finished, pumping the materials into a collecting kettle, recovering nitric acid by reduced pressure distillation in the collecting kettle, and regulating the residual acidic materials to be alkaline by adopting a sodium hydroxide solution;
fully stirring, filtering, removing the completely unreacted nitrified product, regulating the pH value of the filtrate to be acidic, separating out the product at the moment, filtering and drying to obtain the product, and supplementing the unreacted nitrified product into a first or a second storage tank for continuous application;
the molar ratio of 4-methylsulfonyl toluene dissolution to nitric acid in the step (1) is 1.5-20:1;
the molar ratio of nitric acid to 4-methylsulfonyl toluene in the material discharged from the second storage tank in the step (3) is 1.5-25:1;
the mass ratio of the 4-methylsulfonyl toluene to the catalyst is 20-2000:1;
the concentration of nitric acid in the first storage tank is 40-95%, and the concentration of nitric acid in the second storage tank is 50-98%;
the catalyst in the step (1) is as follows: any one or two or more of vanadium pentoxide, cobalt acetate and copper nitrate.
2. The method for synthesizing 2-nitro-4-methylsulfonyl benzoic acid according to claim 1, wherein the liquid outlet end of the first storage tank is communicated with a first metering pump through a first pipeline;
the liquid outlet end of the first tubular reactor is communicated with the liquid inlet end of the second tubular reactor through a second pipeline;
the liquid outlet end of the second tubular reactor is communicated with the collecting kettle through a third pipeline;
the liquid outlet end of the second storage tank is communicated with the liquid inlet end of the three-way mixer through a fourth pipeline;
the top of the collecting kettle is communicated with the air inlet end of the waste gas absorbing kettle through an exhaust pipeline.
3. The method for synthesizing 2-nitro-4-methylsulfonyl benzoic acid according to claim 1 wherein the first tubular reactor is equipped with a plurality of thermometers;
the third pipeline is provided with a back pressure valve.
4. The method for synthesizing 2-nitro-4-methylsulfonyl benzoic acid according to claim 1, wherein the 4-methylsulfonyl toluene fully continuous synthesis 2-nitro-4-methylsulfonyl benzoic acid device further comprises an oxygen supply component communicated with a fourth pipeline;
oxygen is pumped into the fourth pipeline through the oxygen supply component, and enters the second tubular reactor through the three-way mixer.
5. The method for synthesizing 2-nitro-4-methylsulfonyl benzoic acid according to claim 4 wherein the oxygen supply means comprises an oxygen supply tank, the outlet end of the oxygen supply tank being in communication with a fifth conduit, the fifth conduit being fitted with a gas flow controller, the gas flow controller being in communication with a gas buffer tank, the outlet end of the gas buffer tank being in communication with a sixth conduit, the sixth conduit being in communication with a fourth conduit;
an air pressure regulating valve is arranged between the oxygen supply tank and the air flow controller;
and a one-way valve is arranged between the air outlet end of the sixth pipeline and the fourth pipeline.
6. The method for synthesizing 2-nitro-4-methylsulfonyl benzoic acid according to claim 1, wherein the first tubular reactor and the second tubular reactor are made of any one of a metal tube lined with tetrafluoro stainless steel, a steel wire lined with tetrafluoro hose, a zirconium tube, a tantalum tube and the like;
the length of the first tubular reactor is 0.5-30m, and the length of the second tubular reactor is 5-100 m; the first tubular reactor and the second tubular reactor adopt oil bath or externally-added jackets for heat exchange.
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