CN112300033A - Device and method for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene - Google Patents
Device and method for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene Download PDFInfo
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Abstract
The invention discloses a device for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene, 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 collection kettle. The device comprises a first storage tank, a first metering pump, a first tubular reactor, a three-way mixer, a first tubular reactor, a second metering pump, a three-way mixer, a second tubular reactor and a waste gas absorption kettle, wherein the first storage tank is communicated with the first metering pump, the first metering pump is communicated with the first tubular reactor, the first tubular reactor is communicated with the three-way mixer, the second metering pump is communicated with the three-way mixer, the three-way mixer is communicated with the second tubular reactor, the second tubular reactor is communicated with the collection kettle, and the waste gas absorption kettle is communicated with the collection kettle. The device design and the method based on the device realize the synthesis of the target product by adopting a tubular reaction mode, and solve the technical defects of difficult recovery and large pollution amount of the existing kettle type preparation waste acid.
Description
Technical Field
The invention relates to the field of 2-nitro-4-methylsulfonylbenzoic acid synthesis devices, in particular to a device and a method for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene.
Background
2-nitro-4-methylsulfonylbenzoic acid (NMSBA) is an important organic synthesis intermediate, which is mainly used for synthesizing the herbicide mesotrione. Because the mesotrione has the advantages of wide weed control spectrum, good weed control effect, small damage to afterreap crops, safe use and the like, the mesotrione is widely used, stably lives in the front of the corn field herbicide market, can be mixed with other herbicides for use, and the market demand is increased year by year. The prior process for synthesizing 2-nitro-4-methylsulfonylbenzoic acid mainly takes 4-methylsulfonyl toluene as a raw material and is prepared by two steps of reactions of nitration and oxidation.
Synthetic reaction formula of 2-nitro-4-methylsulfonylbenzoic acid
At present, the reaction for preparing the 2-nitro-4-methylsulfonylbenzoic acid mostly adopts a kettle type 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 wastewater amount is large in the industrial preparation process.
In the synthesis method of 2-nitro-4-methylsulfonylbenzoic acid disclosed in the prior art, the nitration reaction mainly uses p-methylsulfonyltoluene, sulfuric acid and nitric acid as raw materials, and the original kettle type process is modified into a continuous flow process which has been reported. For example, the Chinese patent application number is: CN110845373A, CN110759837A and CN110305047A disclose synthesis methods for 2-nitro-4-methylsulfonyltoluene.
In most of the methods reported in the above patent documents, 4-methylsulfonyltoluene is dissolved in sulfuric acid, mixed with a nitric acid-sulfuric acid solution, and continuously fed into a continuous flow reactor for reaction. A large amount of sulfuric acid waste acid is generated in the reaction process, and can be recycled, but on one hand, the post-treatment process is increased, and on the other hand, the sulfuric acid impurities accumulated after being recycled and reused for many times are reduced, and the product quality is reduced.
The Chinese patent application numbers are: CN1995014 reports a method for preparing 2-nitro-4-methylsulfonyl toluene by using a solid super acid catalyst, wherein 4-methylsulfonyl toluene is used as a raw material, solid super acid 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-methylsulfonyltoluene is dissolved by an organic solvent, acetic anhydride and the organic solvent need to be separated after the reaction is finished, and the catalyst also needs to be further treated for reuse.
The synthesis method of 2-nitro-4-methylsulfonylbenzoic acid is various, such as a cyano hydrolysis method and an oxidation method, but substrates of the cyano hydrolysis method are extremely toxic and expensive, and are not suitable for industrial production, and the conventional synthesis method is the oxidation method, wherein 2-nitro-4-methylsulfonylbenzoic acid is prepared by oxidizing methyl on an aromatic ring into carboxyl by using an oxidant.
However, two strong electron-withdrawing groups are connected to the aromatic ring of 2-nitro-4-methylsulfonyl toluene, so that methyl oxidation on the aromatic ring becomes difficult, and therefore, a strong oxidant and a catalyst are needed for accelerating the reaction. There are many oxidation modes reported so far.
Stoichiometric oxidation, and the oxidant is high valence metal salt such as potassium dichromate, potassium permanganate and the like, and has strong oxidizing capability. For example, the Chinese patent application number is: CN201610778084 discloses a method for oxidation of potassium dichromate. However, the method has mild and simple operation conditions and high yield, but can generate heavy metal pollution and is not environment-friendly.
The hydrogen peroxide has strong oxidizing ability and conforms to the green chemical concept. The Chinese patent application numbers are: patents CN102584650A, CN10153383A, etc. report that in this process, hydrogen peroxide is used as an oxidizing agent to oxidize 2-nitro-4-methylsulfonyl toluene in sulfuric acid, but the high yield of 2-nitro-4-methylsulfonyl benzoic acid is to be achieved, the amount of hydrogen peroxide is large, and the production cost is high.
The molecular oxygen is used as an oxidant, so that the cost is low and the environment is protected. However, at normal temperature, the oxygen molecules are in the ground state, the oxidation activity is not high enough, and a catalyst is usually added and the reaction conditions are usually strengthened. The Chinese patent application numbers are: CN106496079A, CN103787934A report a multi-element catalytic system composed of heteropoly acid-metal oxide-halogen. The Chinese patent application numbers are: CN108530326A reports a catalytic oxidation system for N-hydroxylamine compounds. US patent US5591890 reports a catalytic oxidation system with cobalt acetate as catalyst. However, the methods have the defects of complicated preparation and recycling of the catalyst, long reaction time, low safety and the like due to the adoption of a kettle type high-pressure system.
The nitric acid is used for catalytic oxidation, the nitric acid is cheap and easy to obtain, and the oxidation capacity is strong, so that the method is adopted in the current industrial large-scale production. As in the prior art, see in particular: green synthesis study of 2-nitro-4-methylsulfonylbenzoic acid, written in university of sakinzu, zhejiang, 2009,37 (3): 267-271, the process uses nitric acid as oxidant, vanadium pentoxide as catalyst and concentrated sulfuric acid as solvent. Although sulfuric acid can realize higher reaction temperature, a large amount of waste acid is generated after reaction, and the waste acid is difficult to realize indiscriminate application, and the use of high-concentration sulfuric acid enables a dinitration side reaction to easily occur in the reaction process, and the dropwise addition of nitric acid results in long reaction time and low reaction efficiency. And the 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-methylsulfonylbenzoic acid by gas-liquid oxidation, Liu Hu, Anhui chemical industry, 2013,39(04):48-50, and the combination of nitric acid oxidation and molecular oxygen oxidation. But does not address the deficiencies of the nitric acid oxidation process.
Disclosure of Invention
The invention aims to solve the technical problem of providing a device and a method for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyl toluene.
The concept of the invention is as follows:
through the dynamics research of the nitration reaction, the result shows that the 4-methylsulfonylbenzoic acid can realize the rapid nitration reaction under the catalysis of concentrated sulfuric acid under the mild condition, and the substrate nitration reaction is proved to be easy to carry out and the activation energy is lower. The aromatic hydrocarbon nitration reaction is influenced by the concentration of sulfuric acid and the reaction temperature, when the concentration of the sulfuric acid is consistent, the higher the temperature is, the easier the nitration is carried out, and under the condition of a certain temperature, the higher the concentration of the sulfuric acid is, the stronger the nitration capability of the system is. Nitric acid has a strong nitration ability originally, especially when the concentration of nitric acid is high. However, at high temperatures, the oxidation of nitric acid tends to be more pronounced. The flow chemistry technology can realize the accurate control of the reaction condition, and can realize the nitration reaction and inhibit the oxidation reaction by the accurate control of the temperature of the nitration reaction in sections and the allocation of the nitric acid concentration. The results of the research on the oxidation of the nitric acid-sulfuric acid mixed acid show that the nitric acid is easily decomposed or boiled by heating in the reaction process and separated from the reaction system, so that the oxidation performance is reduced and the waste of the nitric acid is caused, and meanwhile, the high-concentration sulfuric acid in the system ensures that the nitric acid is seriously protonated, which shows that the nitration capability is improved and the oxidation capability is reduced. The protonation of nitric acid can be avoided after sulfuric acid is eliminated, and the reaction process is pressurized and strengthened by adopting a fluidization technology, so that the nitric acid can be used under the condition of normal pressure and the temperature higher than the boiling point. Nitric acid is not easy to separate from the reaction system. Adding molecular oxygen, nitric acid is heated to generate free radicals, and basic molecular oxygen can be catalyzed into high-activity oxygen free radicals, so that the dosage of nitric acid is reduced.
The invention solves the technical problems through the following technical scheme:
a device for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene 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 collection 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 a first liquid inlet end of the three-way mixer, and the liquid outlet end of the second metering pump is communicated with a 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 collection kettle;
the device for fully and continuously synthesizing the 2-nitro-4-methylsulfonylbenzoic acid from the 4-methylsulfonyltoluene also comprises a waste gas absorption kettle communicated with the collection kettle.
Preferably, the liquid outlet end of the first storage tank is communicated with a first metering pump through a first pipeline;
the first metering pump is communicated with the first tubular reactor, and 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 collection 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 collection kettle is communicated with the air inlet end of the waste gas absorption kettle through an exhaust pipeline.
Preferably, the first tubular reactor is provided with a plurality of thermometers;
a back pressure valve is assembled on the third pipeline.
Preferably, the device for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene further comprises an oxygen supply component communicated with the fourth pipeline;
and pumping oxygen into the fourth pipeline through the oxygen supply part, wherein the oxygen enters the second tubular reactor through the three-way mixer.
Preferably, the oxygen supply part comprises an oxygen supply tank, the gas outlet end of the oxygen supply tank is communicated with a fifth pipeline, the fifth pipeline is provided with a gas flow controller, the gas flow controller is communicated with a gas buffer tank, the gas 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 assembled between the air outlet end of the sixth pipeline and the fourth pipeline.
The invention also discloses a method for synthesizing 2-nitro-4-methylsulfonylbenzoic 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 the nitric acid, and placing the reaction feed liquid 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-;
(3) pumping the materials in the first storage tank into the first tubular reactor for reaction for 1-30min, discharging the materials in the first tubular reactor after the reaction is finished, discharging the materials in the second storage tank, mixing the materials with the materials discharged from the first tubular reactor, and pumping the materials into the second tubular reactor for oxidation reaction for 20-300 min;
(4) after the oxidation reaction is finished, pumping the material into a collection kettle, carrying out reduced pressure distillation in the collection kettle to recover nitric acid, and adjusting the residual acidic material to be alkaline by adopting a sodium hydroxide solution;
fully stirring and filtering, removing the nitration product which is not completely reacted, adjusting the pH value of the filtrate to acidity, separating out the product, filtering and drying to obtain the product, and supplementing the unreacted nitration product into the first or second storage tank for continuous use.
Preferably, the catalyst is one of a vanadium reagent, a copper reagent, a zirconium reagent and an N-hydroxylamine reagent or a mixture of any two or more of the vanadium reagent, the copper reagent, the zirconium reagent and the 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' -trihydroxy isocyanuric acid.
Preferably, the molar ratio of 4-methylsulfonyltoluene 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 the nitric acid in the first storage tank is 40-95%, and the concentration of the 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 teflon-lined stainless steel metal tube, a steel wire-lined teflon 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 an additional jacket for heat exchange.
Compared with the prior art, the invention has the following advantages:
the invention discloses a device for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene, 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 collection 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 to be separated and purified, so that the reaction procedures are reduced, and the reaction cost is reduced.
4. Continuous production, accurate reaction parameter control and small reaction amplification effect. The safety and the efficiency are effectively improved.
Provides a device which can be used for synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene in a full-continuous way and replaces the traditional kettle type synthesis device.
Drawings
FIG. 1 is a schematic diagram of the overall structure of an embodiment of the present invention;
FIG. 2 is a schematic structural view of an oxygen supplying part in an embodiment of the present invention;
FIG. 3 is a nuclear magnetic spectrum of 2-nitro-4-methylsulfonyltoluene synthesized and prepared in the first tubular reactor in example 4 of the present invention;
FIG. 4 is a nuclear magnetic spectrum of 2-nitro-4-methylsulfonylbenzoic acid synthesized in the second tubular reactor in example 4 of the present invention;
FIG. 5 is a liquid phase diagram of a feed 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 a feed solution after the end of the reaction in the first tubular reactor in example 4 of the present invention.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
Example 14 device for the fully continuous Synthesis of 2-nitro-4-methylsulfonylbenzoic acid from Methylsulfonyluene
As shown in fig. 1-2, a device for fully continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene 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 collection 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 collection kettle 6; the device also comprises a waste gas absorption kettle 7 communicated with the collection 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 the collection 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 collection kettle 6 is communicated with the air inlet end of the waste gas absorption 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; a back pressure valve is fitted to the third pipe and a temperature metering device is fitted to the second tubular reactor 4.
In actual work, it was found that the reaction effect can be improved if an oxidizing gas is introduced into the whole reaction, and therefore, the following design is made:
the device for fully and continuously synthesizing the 2-nitro-4-methylsulfonylbenzoic acid by the 4-methylsulfonyltoluene also comprises an oxygen supply component communicated with the fourth pipeline 21;
oxygen is pumped into the fourth pipeline 21 through the oxygen supply part, and enters the second tubular reactor 4 through the three-way mixer a.
Specifically, the oxygen supply part comprises an oxygen supply tank 8, a fifth pipeline is communicated with the air outlet end of the oxygen supply tank 8, a gas flow controller 11 is assembled on the fifth pipeline, the gas flow controller 11 is communicated with a gas buffer tank 9, a sixth pipeline is communicated with the air outlet end of the gas buffer tank 9, and the sixth pipeline is communicated with a fourth pipeline 21.
An air pressure regulating valve 12 is arranged between the oxygen supply tank 8 and the gas 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 backflow of materials is avoided through the check valve 10.
In the actual working process, in order to increase the contact between oxygen and materials, the second tubular reactor 4 is provided with baffles or added with fillers according to the conventional mode; the baffle plate fillers are used for guiding the reaction materials and promoting the mixing of gas phase and liquid phase, in particular to the reaction material oxygen.
The method is applied to the reaction process, and comprises the following steps:
dissolving a reaction material 4-methylsulfonyltoluene in a nitric acid solution, placing the solution in a first storage tank 1, dissolving a catalyst used for reaction in nitric acid with concentration, placing the solution in a second storage tank 2, and setting the temperature settings of a first tubular reactor 3 and a second tubular reactor 4. The flow rate of the first metering pump 111 and the flow rate of the second metering pump 211 are adjusted, and the materials enter the first tubular reactor 3 and the second tubular reactor 4 for reaction.
The material solution enters a collection kettle 6 for collection, and the waste gas generated in the collection process enters a waste gas absorption kettle 7 for recovery treatment.
The device component design realizes the synthesis of the 2-nitro-4-methylsulfonylbenzoic acid by adopting a tubular reaction mode, and solves the technical defect that the prior art only adopts kettle type reaction to prepare the 2-nitro-4-methylsulfonylbenzoic acid.
EXAMPLE 22 Synthesis of nitro-4-methylsulfonylbenzoic acid
The synthesis steps of the 2-nitro-4-methylsulfonylbenzoic acid are as follows:
as shown in FIG. 1-2, 170g of 4-methylsulfonyltoluene was dissolved in 405g of a 78% nitric acid solution and placed in a first tank 1, and 0.5g of vanadium pentoxide and 3.4g of THICA were dissolved in 1115g of 85% nitric acid and placed in a second tank 2. The first tubular reactor 3 is equally divided into three sections for controlling the temperature, wherein the first section is 85 ℃, the second section is 100 ℃ and the third section is 130 ℃. The second tubular reactor 4 was set to a temperature of 150 ℃. The first metering pump flow rate was 2mL/min and the second metering pump flow rate was 8 mL/min. The pressure was 1.2 MPa. The residence time of the first tubular reactor 3 was 15min (after the reaction, after sampling and purification, nuclear magnetic detection was performed, and nuclear magnetic results are shown in fig. 3), the reaction solution flowing out of the first tubular reactor was mixed with the feed solution delivered by the second metering pump in a T-shaped mixer without treatment and then entered the second tubular reactor 4 for 50min (after the reaction, after sampling and purification, nuclear magnetic detection was performed, and nuclear magnetic results are shown in fig. 4).
And (3) carrying out reduced pressure rotary evaporation on the product in the collection kettle 6 until the product is pasty. Adjusting the pasty product to be alkaline by using a sodium hydroxide solution under the condition of fully stirring, continuously stirring for 20min, then filtering to obtain yellow filtrate, dropwise adding hydrochloric acid or dilute nitric acid recovered after distillation into the filtrate until the filtrate is acidic, precipitating a large amount of light yellow solid, and drying to obtain 192g of light yellow solid, wherein the one-way yield is 78% and the purity is 99%. After the alkali washing, the filter cake was subjected to beating washing with a small amount of 65% nitric acid and filtered to obtain 46g of a white solid, which was unreacted 2-nitro-4-methylsulfonyltoluene.
Liquid phase detection is carried out on a sample at the outlet of the first tubular reactor 3, and the nitration yield of the 4-methylsulfonyl toluene is 99 percent.
Example Synthesis of 32-Nitro-4-Methylsulfonylbenzoic acid
As shown in fig. 1-2, this example synthesizes 2-nitro-4-methylsulfonylbenzoic acid based on the apparatus disclosed in example 1, and includes the following steps:
170g of 4-methylsulfonyltoluene is dissolved in 540g of 70% nitric acid solution and placed in a first storage tank 1, 0.5g of vanadium pentoxide and 1.0g of zirconium acetate are dissolved in 1260g of 90% nitric acid and placed in a second storage tank 2. The first tubular reactor 3 is equally divided into two sections for controlling the temperature, wherein the temperature of the first section is 120 ℃, and the temperature of the second section is 130 ℃. The second tubular reactor 4 was set to a temperature of 160 ℃. The first metering pump flow rate was 2mL/min and the second metering pump flow rate was 6.3 mL/min. The pressure was 1.5 MPa.
The residence time in the first tubular reactor 3 was 12min and in the second tubular reactor 480 min. And (3) carrying out reduced pressure rotary evaporation on the product in the collection kettle 6 until the product is pasty. Adjusting the pasty product to be alkaline by using a sodium hydroxide solution under the condition of fully stirring, continuously stirring for 20min, then filtering to obtain yellow filtrate, dropwise adding hydrochloric acid or dilute nitric acid recovered after distillation into the filtrate until the filtrate is acidic, precipitating a large amount of light yellow solid, and drying to obtain 233g of earthy yellow solid, wherein the one-way yield is 95%, and the purity is 98%.
After the alkali washing, the filter cake was subjected to beating washing with a small amount of 65% nitric acid and filtered to obtain 10g of a white solid, which was unreacted 2-nitro-4-methylsulfonyltoluene. Liquid phase detection is carried out on a sample at the outlet of the first tubular reactor 3, and the nitration yield of the 4-methylsulfonyl toluene is 99 percent.
Example 42 Synthesis of nitro-4-methylsulfonylbenzoic acid
As shown in fig. 1-2, this example synthesizes 2-nitro-4-methylsulfonylbenzoic acid based on the apparatus disclosed in example 1, and includes the following steps:
170g of 4-methylsulfonyltoluene are dissolved in 405g of a 78% nitric acid solution and placed in a first storage tank 1, and 0.5g of vanadium pentoxide and 1.0g of copper nitrate are dissolved in 760g of a 90% nitric acid solution and placed in a second storage tank 2. The first tubular reactor 3 is equally divided into two sections for controlling the temperature, wherein the temperature of the first section is 120 ℃, and the temperature of the second section is 130 ℃. The second tubular reactor 4 was set to a temperature of 160 ℃. The first metering pump flow is 2mL/min, the second metering pump flow is 5mL/min, and the oxygen flow is 20 sccm. The pressure was 1.8 MPa. 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 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 60min (after the reaction, the results of sampling and detection are shown in FIG. 5, and the results of nuclear magnetic detection after purification of the reaction solution are shown in FIG. 2). And (3) carrying out reduced pressure rotary evaporation on the product in the collection kettle 6 until the product is pasty. Adjusting the pasty product to be alkaline by using a sodium hydroxide solution under the condition of fully stirring, continuously stirring for 20min, then filtering to obtain yellow filtrate, dropwise adding hydrochloric acid or dilute nitric acid recovered after distillation into the filtrate until the filtrate is acidic, precipitating a large amount of light yellow solid, and drying to obtain 240g of yellow solid, wherein the once-through yield is 98% and the purity is 99%. After the alkali washing, the filter cake was subjected to beating washing with a small amount of 65% nitric acid and filtered to obtain 2.5g of a white solid, which was unreacted 2-nitro-4-methylsulfonyltoluene. Liquid phase detection is carried out by sampling at the outlet of the first tubular reactor 3 (the detection result is shown in figure 6, and nuclear magnetic detection is carried out after the reaction liquid is purified, and the result is shown in figure 1), and the nitration yield of the 4-methylsulfonyltoluene is 99%.
Example 52 Synthesis of nitro-4-methylsulfonylbenzoic acid
As shown in fig. 1-2, this example synthesizes 2-nitro-4-methylsulfonylbenzoic acid based on the apparatus disclosed in example 1, and includes the following steps:
145g of 4-methylsulfonyltoluene is dissolved in 335g of 80% nitric acid solution and placed in a first storage tank 1, 25g of recovered unreacted 2-nitro-4-methylsulfonyltoluene, 0.5g of vanadium pentoxide and 3.0g of THICA are dissolved in 1260g of 80% nitric acid and placed in a second storage tank 2. The first tubular reactor 3 is equally divided into two sections with the temperature controlled, the first section is 115 ℃ and the second section is 132 ℃. The second tubular reactor 4 was set to a temperature of 155 ℃.
The first metering pump flow rate was 2mL/min and the second metering pump flow rate was 7 mL/min. The pressure was 1.5 MPa. The residence time in the first tubular reactor 3 was 15min and in the second tubular reactor 480 min. And (3) carrying out reduced pressure rotary evaporation on the product in the collection kettle 6 until the product is pasty. Adjusting the pasty product to be alkaline by using a sodium hydroxide solution under the condition of fully stirring, continuously stirring for 20min, then filtering to obtain yellow filtrate, dropwise adding hydrochloric acid or dilute nitric acid recovered after distillation into the filtrate until the filtrate is acidic, precipitating a large amount of light yellow solid, and drying to obtain 221g of earthy yellow solid, wherein the one-way yield is 90% and the purity is 98%.
After the alkali washing, the filter cake was subjected to beating washing with a small amount of 65% nitric acid and filtered to obtain 20g of a white solid, which was unreacted 2-nitro-4-methylsulfonyltoluene. Liquid phase detection is carried out on a sample at the outlet of the first tubular reactor 3, and the nitration yield of the 4-methylsulfonyl toluene is 99 percent.
EXAMPLE 62 Synthesis of nitro-4-methylsulfonylbenzoic acid
As shown in fig. 1-2, this example synthesizes 2-nitro-4-methylsulfonylbenzoic acid based on the apparatus disclosed in example 1, and includes the following steps:
170g of 4-methylsulfonyltoluene are dissolved in 540g of 70% nitric acid solution and placed in a first storage tank 1, and 0.5g of vanadium pentoxide, 1.0g of copper nitrate and 2.5g of THICA are dissolved in 1260g of 90% nitric acid and placed in a second storage tank 2. The first tubular reactor 3 is equally divided into two sections for controlling the temperature, wherein the temperature of the first section is 120 ℃, and the temperature of the second section is 130 ℃. The second tubular reactor 4 was set to a temperature of 160 ℃. The first metering pump flow rate was 4mL/min and the second metering pump flow rate was 8.5 mL/min. The pressure was 1.5 MPa. The residence time in the first tubular reactor 3 was 12min and in the second tubular reactor 4 60 min. And (3) carrying out reduced pressure rotary evaporation on the product in the collection kettle 6 until the product is pasty. Adjusting the pasty product to be alkaline by using a sodium hydroxide solution under the condition of fully stirring, continuously stirring for 20min, then filtering to obtain yellow filtrate, dropwise adding hydrochloric acid or dilute nitric acid recovered after distillation into the filtrate until the filtrate is acidic, precipitating a large amount of light yellow solid, and drying to obtain 211g of earthy yellow solid, wherein the one-way yield is 86% and the purity is 99%. After the alkali washing, the filter cake was subjected to beating washing with a small amount of 65% nitric acid and filtered to obtain 10g of a white solid, which was unreacted 2-nitro-4-methylsulfonyltoluene. Liquid phase detection is carried out on a sample at the outlet of the first tubular reactor 3, and the nitration yield of the 4-methylsulfonyl toluene is 99 percent.
By the complete tracking of the reaction and the mass analysis, a small amount of products are completely decomposed in the oxidation stage. Therefore, the recovered 2-nitro-4-methylsulfonyl toluene is less than the theoretical value.
Example 7 comparative prior art
The Chinese patent application number is as follows: CN104557639A as comparative example 1; the Chinese patent application number is as follows: CN104803815A as comparative example 2; the technical method reported in the prior literature is taken as a comparative example 3; the process method 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 prior art, 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 kept equal, and the use of sulfuric acid is abandoned, although the use amount of nitric acid is increased, the recycling is convenient, and the cost is lower.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The device for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene is characterized by comprising 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 collection 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 a first liquid inlet end of the three-way mixer, and the liquid outlet end of the second metering pump is communicated with a 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 collection kettle;
the device for fully and continuously synthesizing the 2-nitro-4-methylsulfonylbenzoic acid from the 4-methylsulfonyltoluene also comprises a waste gas absorption kettle communicated with the collection kettle.
2. The device for fully and continuously synthesizing 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene according to claim 1, wherein the liquid outlet end of the first storage tank is communicated with the first metering pump through a first pipeline;
the first metering pump is communicated with the first tubular reactor, and 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 collection 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 collection kettle is communicated with the air inlet end of the waste gas absorption kettle through an exhaust pipeline.
3. The device for the full-continuous synthesis of 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene according to claim 1, wherein the first tubular reactor is equipped with a plurality of thermometers;
a back pressure valve is assembled on the third pipeline.
4. The device for the full-continuous synthesis of 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene according to claim 1, wherein the device for the full-continuous synthesis of 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene further comprises an oxygen supply component communicated with the fourth pipeline;
and pumping oxygen into the fourth pipeline through the oxygen supply part, wherein the oxygen enters the second tubular reactor through the three-way mixer.
5. The device for the fully continuous synthesis of 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene according to claim 4, wherein the oxygen supply component comprises an oxygen supply tank, the gas outlet end of the oxygen supply tank is communicated with a fifth pipeline, the fifth pipeline is equipped with a gas flow controller, the gas flow controller is communicated with a gas buffer tank, the gas outlet end of the gas buffer tank is communicated with a sixth pipeline, and the sixth pipeline is communicated with a fourth pipeline;
a gas pressure regulating valve is assembled between the oxygen supply tank and the gas flow controller;
and a one-way valve is assembled between the air outlet end of the sixth pipeline and the fourth pipeline.
6. A method for synthesizing 2-nitro-4-methylsulfonylbenzoic acid based on the apparatus for the fully continuous preparation of 2-nitro-4-methylsulfonylbenzoic acid from 4-methylsulfonyltoluene according to any one of claims 1 to 4, 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 the nitric acid, and placing the reaction feed liquid 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-;
(3) pumping the materials in the first storage tank into the first tubular reactor for reaction for 1-30min, discharging the materials in the first tubular reactor after the reaction is finished, discharging the materials in the second storage tank, mixing the materials with the materials discharged from the first tubular reactor, and pumping the materials into the second tubular reactor for oxidation reaction for 20-300 min;
(4) after the oxidation reaction is finished, pumping the material into a collection kettle, carrying out reduced pressure distillation in the collection kettle to recover nitric acid, and adjusting the residual acidic material to be alkaline by adopting a sodium hydroxide solution;
fully stirring and filtering, removing the nitration product which is not completely reacted, adjusting the pH value of the filtrate to acidity, separating out the product, filtering and drying to obtain the product, and supplementing the unreacted nitration product into the first or second storage tank for continuous use.
7. The method for synthesizing 2-nitro-4-methylsulfonylbenzoic acid according to claim 6, wherein 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.
8. The method for synthesizing 2-nitro-4-methylsulfonylbenzoic acid according to claim 7, wherein 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' -trihydroxy isocyanuric acid.
9. The method for synthesizing 2-nitro-4-methylsulfonylbenzoic acid according to claim 8, wherein the molar ratio of 4-methylsulfonyltoluene solution to nitric acid in 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 the nitric acid in the first storage tank is 40-95%, and the concentration of the nitric acid in the second storage tank is 50-98%.
10. The method of synthesizing 2-nitro-4-methylsulfonylbenzoic acid according to claim 9, wherein the first tubular reactor and the second tubular reactor are made of any one of a tetrafluoro-lined stainless steel metal tube, a tetrafluoro-lined steel hose, a zirconium tube, a tantalum tube, etc.;
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 an additional jacket for heat exchange.
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