CN110172023A - A kind of method of adiabatic nitration preparation mononitrotoluene - Google Patents
A kind of method of adiabatic nitration preparation mononitrotoluene Download PDFInfo
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- CN110172023A CN110172023A CN201910269638.8A CN201910269638A CN110172023A CN 110172023 A CN110172023 A CN 110172023A CN 201910269638 A CN201910269638 A CN 201910269638A CN 110172023 A CN110172023 A CN 110172023A
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- mononitrotoluene
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
- C07C201/06—Preparation of nitro compounds
- C07C201/08—Preparation of nitro compounds by substitution of hydrogen atoms by nitro groups
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Abstract
The present invention relates to a kind of methods of adiabatic nitration preparation mononitrotoluene, belong to chemical production technical field.This method uses dilute sulfuric acid as solvent, and fuming nitric aicd realizes that the highly selective mono-nitration of high temperature of toluene, conversion ratio are greater than 99.9%, product purity is greater than 98.7%, and dinitrotoluene (DNT) by-product is less than 1% as nitrating agent under adiabatic condition.The method of adiabatic nitration preparation mononitrotoluene of the invention, compared with traditional batch low-temperature heat exchange method, essential safety, the maximum temperature that reaction heat makes reaction system heat up is well below explosion danger temperature.Adiabatic nitration therein does not have to cryogenic media and exchanges heat, therefore saved a large amount of energy consumptions, and the production cost of mononitrotoluene is greatly reduced.When high temperature nitrifies, reaction speed is fast, and material does not accumulate, and will not generate temperature runaway accident；And high temperature nitrifies, and is conducive to improve materials conversion rate and nitric acid utilization rate.
Description
Technical field
The present invention relates to a kind of methods of adiabatic nitration preparation mononitrotoluene, belong to chemical production technical field.
Background technique
Mononitrotoluene is important fine chemicals intermediate, including ortho-methylnitrobenzene, meta-nitrotoluene and to nitro
Three kinds of isomers of toluene are widely used in the industries such as medicine, pesticide and dyestuff.Such as para-nitrotoluene is used to manufacture DSD
Acid, open-chain crown ether and TNT, ortho-methylnitrobenzene are used to manufacture o-toluidine and TNT, and meta-nitrotoluene is used to manufacture a methyl
Aniline.Currently, domestic mononitrotoluene design production can up to 370,000 tons/year.
Toluene mono-nitration reaction route figure is shown in Fig. 1.It is widely used for preparing the technique of mononitrotoluene at present being nitration mixture (sulfuric acid
And nitric acid) nitration processes, which the use of 95% sulfuric acid is solvent and 98% nitric acid is nitrating agent, uses low-temperature cooling media
Low-temp reaction process is maintained with the inner coil pipe of larger heat exchange area.There are huge security risks for the technique, once heat exchange is
There are mechanical or other failures and stops working in system, and the temperature of reaction system out of control immediately can set off an explosion.In addition, maintaining low
Heat exchange needed for temperature reaction brings very high energy consumption；High-concentration sulfuric acid causes dinitrotoluene (DNT) byproduct to increase, and yield is caused to drop
Low and subsequent product purification difficult, increased costs；High-concentration sulfuric acid leads to wastewater treatment using reaction system color burn is also made
Difficulty, increased costs.Under the requirement of safe green production, the toluene mono-nitration technology for developing a kind of essential safety has very
Important meaning.
Summary of the invention
The purpose of the present invention is to propose to a kind of methods of adiabatic nitration preparation mononitrotoluene, deposit for current nitration processes
Shortcoming, especially in the presence of major safety risks, use dilute sulfuric acid as solvent, fuming nitric aicd is as nitrification examination
The highly selective mono-nitration of high temperature of toluene is realized in agent under adiabatic condition.Conversion ratio is greater than 99.9%, and product purity is greater than
98.7%, dinitrotoluene (DNT) by-product is less than 1%.
The method of adiabatic nitration preparation mononitrotoluene proposed by the present invention, comprising the following steps:
(1) dilute sulfuric acid that mass concentration is 60%~80% is prepared；
(2) control temperature is lower than 35 degrees Celsius, and mass concentration is slowly added drop-wise in dilute sulfuric acid for 98% concentrated nitric acid and is configured
The mass ratio of mixed acid solution, dilute sulfuric acid and concentrated nitric acid is 12:(25~1)；
(3) dilute sulfuric acid prepared by above-mentioned steps (1) is mutually mixed with toluene 6.96:1 in mass ratio, mixing speed is
1000 revolutions per seconds, mixing time is 5 minutes, obtains mixed solution；
(4) at room temperature, the mixed acid solution of step (2) preparation is once added in the mixed solution that step (3) obtains, is added
Mixed acid solution and mixed solution mass ratio be (0.4~1.6): 1, so that reaction temperature is reached 50~90 DEG C, the reaction time 1
~10 minutes, it is naturally cooling to room temperature, obtains reaction mixture；
(5) reaction mixture of step (4) is being stored at room temperature 30 minutes, is then using separatory funnel split-phase, separates
Layer organic phase and lower layer's acid phase, the sodium hydrate aqueous solution and pure water for being successively 10% with concentration, washing has respectively at room temperature
Machine mutually twice, until the pH value of organic phase is neutrality, obtains mononitrotoluene product.
The method of adiabatic nitration preparation mononitrotoluene proposed by the present invention, its advantage is that:
1, the method for adiabatic nitration of the invention preparation mononitrotoluene, compared with traditional batch low-temperature heat exchange method, this
Matter safety, the maximum temperature that reaction heat makes reaction system heat up is well below explosion danger temperature.
2, the method for the present invention is adiabatic nitration, does not have to cryogenic media and exchanges heat, therefore saved a large amount of energy consumptions, list is greatly reduced
The production cost of nitrotoleune.
3, for the method for the present invention when high temperature nitrifies, reaction speed is fast, and material does not accumulate, and will not generate temperature runaway accident；And
And high temperature nitrifies, and is conducive to improve materials conversion rate and nitric acid utilization rate, wherein conversion ratio is greater than 99.9%, and product purity is greater than
98.7%, dinitrotoluene (DNT) by-product is less than 1%.
4, toluene and sulfuric acid concentration used in the method for the present invention are low, and the selectivity of mononitrotoluene is high, dinitrotoluene (DNT)
By-products content is low, and reaction system is of light color, and purifying products and wastewater treatment are simple, significantly save the cost.
5, the dilute sulfuric acid in the method for the present invention can also be recycled after being simply concentrated, further decrease the life of product
Produce cost.
Detailed description of the invention
Fig. 1 is the synthetic route chart of mononitrotoluene in prior art.
Specific embodiment
The method of adiabatic nitration preparation mononitrotoluene proposed by the present invention, comprising the following steps:
(1) dilute sulfuric acid that mass concentration is 60%~80% is prepared；
(2) control temperature is lower than 35 degrees Celsius, and mass concentration is slowly added drop-wise in dilute sulfuric acid for 98% concentrated nitric acid and is configured
The mass ratio of mixed acid solution, dilute sulfuric acid and concentrated nitric acid is 12:(25~1)；
(3) dilute sulfuric acid prepared by above-mentioned steps (1) is mutually mixed with toluene 6.96:1 in mass ratio, mixing speed is
1000 revolutions per seconds, mixing time is 5 minutes, obtains mixed solution；
(4) at room temperature, the mixed acid solution of step (2) preparation is once added in the mixed solution that step (3) obtains, is added
Mixed acid solution and mixed solution mass ratio be (0.4~1.6): 1, so that reaction temperature is reached 50~90 DEG C, the reaction time 1
~10 minutes, it is naturally cooling to room temperature, obtains reaction mixture；
(5) reaction mixture of step (4) is being stored at room temperature 30 minutes, is then using separatory funnel split-phase, separates
Layer organic phase and lower layer's acid phase, the sodium hydrate aqueous solution and pure water for being successively 10% with concentration, washing has respectively at room temperature
Machine mutually twice, until the pH value of organic phase is neutrality, obtains mononitrotoluene product.
The embodiment of the method for the present invention introduced below:
Embodiment 1
(1) 640 grams of dilute sulfuric acid that mass concentration is 60% are prepared；
(2) control temperature is lower than 35 degrees Celsius, and the concentrated nitric acid that 32 gram mass concentration are 98% is slowly added drop-wise to 320 grams
Mixed acid solution is prepared in 60% dilute sulfuric acid；
(3) 320 grams of dilute sulfuric acids of above-mentioned steps (1) preparation and 46 grams of toluene are added at room temperature in 1L there-necked flask,
Unlatching is stirred, and mixing speed is 1000 revolutions per seconds, and mixing time is 5 minutes；
(4) at room temperature, in the mixed liquor that step (2) preparation is once added in the nitration mixture that step (3) obtains, reaction system is fast
After speed is warming up to 65 DEG C, and start to cool down quickly, can stop reacting after temperature drops to room temperature, entire reaction process is 8 points
Clock；
(5) reaction mixture of step (4) is being stored at room temperature 30 minutes, is then using separatory funnel split-phase, separates
Layer organic phase and lower layer's acid phase are successively used the sodium hydrate aqueous solution and 20mL pure water of 20mL10%, are washed respectively at room temperature
Organic phase twice, until the pH value of organic phase is neutrality, obtains mononitrotoluene product.Gas chromatographic detection result are as follows: toluene
(0.4%), ortho-methylnitrobenzene (58.5%), meta-nitrotoluene (4.2%), para-nitrotoluene (36.4%), dinitrotoluene (DNT)
(0.5%).
Embodiment 2
(1) 480 grams of dilute sulfuric acid that mass concentration is 60% are prepared；
(2) control temperature is lower than 35 degrees Celsius, and the concentrated nitric acid that 32 gram mass concentration are 98% is slowly added drop-wise to 160 grams
Mixed acid solution is prepared in 60% dilute sulfuric acid；
(3) 320 grams of dilute sulfuric acids of above-mentioned steps (1) preparation and 46 grams of toluene are added at room temperature in 1L there-necked flask,
Unlatching is stirred, and mixing speed is 1000 revolutions per seconds, and mixing time is 5 minutes；
(4) at room temperature, in the mixed liquor that step (2) preparation is once added in the nitration mixture that step (3) obtains, reaction system is fast
After speed is warming up to 85 DEG C, and start to cool down quickly, can stop reacting after temperature drops to room temperature, entire reaction process is 10 points
Clock；
(5) reaction mixture of step (4) is being stored at room temperature 30 minutes, is then using separatory funnel split-phase, separates
Layer organic phase and lower layer's acid phase are successively used the sodium hydrate aqueous solution and 20mL pure water of 20mL10%, are washed respectively at room temperature
Organic phase twice, until the pH value of organic phase is neutrality, obtains mononitrotoluene product.Gas chromatographic detection result are as follows: toluene
(0.2%), ortho-methylnitrobenzene (58.1%), meta-nitrotoluene (4.6%), para-nitrotoluene (36.2%), dinitrotoluene (DNT)
(0.9%).
Embodiment 3
(1) 640 grams of dilute sulfuric acid that mass concentration is 70% are prepared；
(2) control temperature is lower than 35 degrees Celsius, and the concentrated nitric acid that 32 gram mass concentration are 98% is slowly added drop-wise to 320 grams
Mixed acid solution is prepared in 70% dilute sulfuric acid；
(3) 320 grams of dilute sulfuric acids of above-mentioned steps (1) preparation and 46 grams of toluene are added at room temperature in 1L there-necked flask,
Unlatching is stirred, and mixing speed is 1000 revolutions per seconds, and mixing time is 5 minutes；
(4) at room temperature, in the mixed liquor that step (2) preparation is once added in the nitration mixture that step (3) obtains, reaction system is fast
After speed is warming up to 60 DEG C, and start to cool down quickly, can stop reacting after temperature drops to room temperature, entire reaction process is 6 points
Clock；
(5) reaction mixture of step (4) is being stored at room temperature 30 minutes, is then using separatory funnel split-phase, separates
Layer organic phase and lower layer's acid phase are successively used the sodium hydrate aqueous solution and 20mL pure water of 20mL10%, are washed respectively at room temperature
Organic phase twice, until the pH value of organic phase is neutrality, obtains mononitrotoluene product.Gas chromatographic detection result are as follows: toluene
(0.4%), ortho-methylnitrobenzene (58.3%), meta-nitrotoluene (4.1%), para-nitrotoluene (36.6%), dinitrotoluene (DNT)
(0.6%).
Embodiment 4
(1) 640 grams of dilute sulfuric acid that mass concentration is 80% are prepared；
(2) control temperature is lower than 35 degrees Celsius, and the concentrated nitric acid that 32 gram mass concentration are 98% is slowly added drop-wise to 320 grams
Mixed acid solution is prepared in 80% dilute sulfuric acid；
(3) 320 grams of dilute sulfuric acids of above-mentioned steps (1) preparation and 46 grams of toluene are added at room temperature in 1L there-necked flask,
Unlatching is stirred, and mixing speed is 1000 revolutions per seconds, and mixing time is 5 minutes；
(4) at room temperature, in the mixed liquor that step (2) preparation is once added in the nitration mixture that step (3) obtains, reaction system is fast
After speed is warming up to 75 DEG C, and start to cool down quickly, can stop reacting after temperature drops to room temperature, entire reaction process is 4 points
Clock；
(5) reaction mixture of step (4) is being stored at room temperature 30 minutes, is then using separatory funnel split-phase, separates
Layer organic phase and lower layer's acid phase are successively used the sodium hydrate aqueous solution and 30mL pure water of 30mL10%, are washed respectively at room temperature
Organic phase twice, until the pH value of organic phase is neutrality, obtains mononitrotoluene product.Gas chromatographic detection result are as follows: toluene
(0.1%), ortho-methylnitrobenzene (58.4%), meta-nitrotoluene (4.0%), para-nitrotoluene (36.6%), dinitrotoluene (DNT)
(0.9%).
Embodiment 5
(1) 800 grams of dilute sulfuric acid that mass concentration is 60% are prepared；
(2) control temperature is lower than 35 degrees Celsius, and the concentrated nitric acid that 32 gram mass concentration are 98% is slowly added drop-wise to 480 grams
Mixed acid solution is prepared in 60% dilute sulfuric acid；
(3) 320 grams of dilute sulfuric acids of above-mentioned steps (1) preparation and 46 grams of toluene are added at room temperature in 1L there-necked flask,
Unlatching is stirred, and mixing speed is 1000 revolutions per seconds, and mixing time is 5 minutes；
(4) at room temperature, in the mixed liquor that step (2) preparation is once added in the nitration mixture that step (3) obtains, reaction system is fast
After speed is warming up to 50 DEG C, and start to cool down quickly, can stop reacting after temperature drops to room temperature, entire reaction process is 7 points
Clock；
(5) reaction mixture of step (4) is being stored at room temperature 30 minutes, is then using separatory funnel split-phase, separates
Layer organic phase and lower layer's acid phase are successively used the sodium hydrate aqueous solution and 20mL pure water of 20mL10%, are washed respectively at room temperature
Organic phase twice, until the pH value of organic phase is neutrality, obtains mononitrotoluene product.Gas chromatographic detection result are as follows: toluene
(0.7%), ortho-methylnitrobenzene (58.8%), meta-nitrotoluene (3.9%), para-nitrotoluene (36.4%), dinitrotoluene (DNT)
(0.2%).
Claims (1)
1. a kind of method of adiabatic nitration preparation mononitrotoluene, it is characterised in that method includes the following steps:
(1) dilute sulfuric acid that mass concentration is 60%~80% is prepared；
(2) control temperature is lower than 35 degrees Celsius, and mass concentration is slowly added drop-wise in dilute sulfuric acid for 98% concentrated nitric acid and configures nitration mixture
The mass ratio of solution, dilute sulfuric acid and concentrated nitric acid is 12:(25~1)；
(3) dilute sulfuric acid prepared by above-mentioned steps (1) is mutually mixed with toluene 6.96:1 in mass ratio, mixing speed 1000
Revolutions per second, mixing time is 5 minutes, obtains mixed solution；
(4) at room temperature, the mixed acid solution of step (2) preparation is once added in the mixed solution that step (3) obtains, addition mixes
The mass ratio of acid solution and mixed solution is (0.4~1.6): 1, so that reaction temperature is reached 50~90 DEG C, the reaction time is 1~10
Minute, it is naturally cooling to room temperature, obtains reaction mixture；
(5) reaction mixture of step (4) is being stored at room temperature 30 minutes, is then using separatory funnel split-phase, separating upper layer has
Machine phase and lower layer's acid phase, the sodium hydrate aqueous solution and pure water for being successively 10% with concentration, wash organic phase respectively at room temperature
Twice, until the pH value of organic phase is neutrality, mononitrotoluene product is obtained.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111004124A (en) * | 2019-12-10 | 2020-04-14 | 清华大学 | Method for preparing mononitrotoluene by continuously and adiabatically nitrifying toluene at high temperature |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111004124A (en) * | 2019-12-10 | 2020-04-14 | 清华大学 | Method for preparing mononitrotoluene by continuously and adiabatically nitrifying toluene at high temperature |
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