CN114890901A - Synthesis method for synthesizing m-toluidine by 2-chloro-3-nitrotoluene one-step method - Google Patents
Synthesis method for synthesizing m-toluidine by 2-chloro-3-nitrotoluene one-step method Download PDFInfo
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- toluidine
- nitrotoluene
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- JJYPMNFTHPTTDI-UHFFFAOYSA-N 3-methylaniline Chemical compound CC1=CC=CC(N)=C1 JJYPMNFTHPTTDI-UHFFFAOYSA-N 0.000 title claims abstract description 267
- XTSGZXRUCAWXKY-UHFFFAOYSA-N 2-chloro-1-methyl-3-nitrobenzene Chemical compound CC1=CC=CC([N+]([O-])=O)=C1Cl XTSGZXRUCAWXKY-UHFFFAOYSA-N 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 35
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 20
- 238000001308 synthesis method Methods 0.000 title claims abstract description 11
- 238000006722 reduction reaction Methods 0.000 claims abstract description 67
- 230000009467 reduction Effects 0.000 claims abstract description 53
- 239000003054 catalyst Substances 0.000 claims abstract description 41
- 229910052751 metal Inorganic materials 0.000 claims abstract description 24
- 239000002184 metal Substances 0.000 claims abstract description 24
- 239000001257 hydrogen Substances 0.000 claims abstract description 20
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 20
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000002156 mixing Methods 0.000 claims abstract description 3
- 239000012043 crude product Substances 0.000 claims description 64
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 60
- 238000005406 washing Methods 0.000 claims description 35
- 229910052757 nitrogen Inorganic materials 0.000 claims description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 27
- 239000000047 product Substances 0.000 claims description 19
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 230000018044 dehydration Effects 0.000 claims description 14
- 238000006297 dehydration reaction Methods 0.000 claims description 14
- 238000004821 distillation Methods 0.000 claims description 13
- 239000007789 gas Substances 0.000 claims description 13
- 238000003825 pressing Methods 0.000 claims description 11
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 8
- 150000004994 m-toluidines Chemical class 0.000 claims description 7
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 6
- UKVIEHSSVKSQBA-UHFFFAOYSA-N methane;palladium Chemical compound C.[Pd] UKVIEHSSVKSQBA-UHFFFAOYSA-N 0.000 claims description 6
- 238000010189 synthetic method Methods 0.000 claims description 6
- 229910052725 zinc Inorganic materials 0.000 claims description 6
- 239000011701 zinc Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 238000005086 pumping Methods 0.000 claims description 5
- 238000007664 blowing Methods 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 11
- 230000015572 biosynthetic process Effects 0.000 abstract description 9
- 238000003786 synthesis reaction Methods 0.000 abstract description 9
- 239000002994 raw material Substances 0.000 abstract description 7
- QZYHIOPPLUPUJF-UHFFFAOYSA-N 3-nitrotoluene Chemical compound CC1=CC=CC([N+]([O-])=O)=C1 QZYHIOPPLUPUJF-UHFFFAOYSA-N 0.000 abstract description 4
- 239000002699 waste material Substances 0.000 abstract description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- 238000001514 detection method Methods 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 238000010992 reflux Methods 0.000 description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 7
- 238000005070 sampling Methods 0.000 description 6
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 125000003277 amino group Chemical group 0.000 description 4
- 125000000449 nitro group Chemical group [O-][N+](*)=O 0.000 description 4
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 3
- 238000002845 discoloration Methods 0.000 description 3
- 238000004817 gas chromatography Methods 0.000 description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000005984 hydrogenation reaction Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000741 silica gel Substances 0.000 description 2
- 229910002027 silica gel Inorganic materials 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000006298 dechlorination reaction Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
- C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
- C07C209/36—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups by reduction of nitro groups bound to carbon atoms of six-membered aromatic rings in presence of hydrogen-containing gases and a catalyst
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/82—Purification; Separation; Stabilisation; Use of additives
- C07C209/84—Purification
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/82—Purification; Separation; Stabilisation; Use of additives
- C07C209/86—Separation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to the technical field of m-toluidine synthesis, in particular to a synthesis method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene in a one-step method. The method comprises the following steps: adding 2-chloro-3-nitrotoluene and a metal catalyst, and mixing hydrogen to perform a reduction reaction to synthesize m-toluidine. In the prior art, m-toluidine is synthesized by using m-nitrotoluene as a raw material. Compared with the prior art, the invention provides a novel m-toluidine synthesis method, which widens the raw material source of m-toluidine synthesis, and has the advantages of simple process route and effective reduction of three wastes generated in the synthesis process.
Description
Technical Field
The invention relates to the technical field of m-toluidine synthesis, in particular to a synthesis method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene in a one-step method.
Background
M-toluidine, a colorless oily liquid, is an important organic synthetic intermediate, and is widely applied to the synthesis of medicines, dyes and pesticides. The existing preparation method is to take m-nitrotoluene as a raw material, add metal catalysts such as iron, nickel and the like, carry out hydrogenation reduction, remove water in a crude product by layered dehydration, and then carry out rectification to obtain qualified m-toluidine.
Chinese patent discloses a catalyst for preparing m-toluidine by gas phase hydrogenation of m-nitrotoluene, a preparation method and a regeneration method thereof [ application No.: CN200810234622.5, publication No.: CN101733099A ] includes: the catalyst takes SiO2 as a carrier and copper as a main active component, and takes the weight of the catalyst as a reference, Cu accounts for 10-30%, and the balance is SiO 2. When preparing the catalyst, weighing copper nitrate and silica gel, and adding distilled water into the copper nitrate until the copper nitrate is completely dissolved; adding ammonia solution until no precipitate is generated in the solution; adjusting the pH value, adding silica gel into the prepared solution, and stirring; filtering the obtained solution, washing until the filtrate is colorless, drying, and roasting to obtain the final product. Although the technical scheme of the patent provides a novel catalyst, when m-toluidine is synthesized, m-nitrotoluene is still used as a basic raw material, and a brand-new m-toluidine synthesis method cannot be provided.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a synthetic method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene in a one-step method.
In order to solve the technical problems, the invention provides the following technical scheme:
a synthetic method for synthesizing m-toluidine by 2-chloro-3-nitrotoluene through a one-step method comprises the following steps: adding 2-chloro-3-nitrotoluene and a metal catalyst, and mixing hydrogen to perform a reduction reaction to synthesize m-toluidine.
In the actual reaction process, under the action of a metal catalyst, hydrogen and 2-chloro-3-nitrotoluene are subjected to reduction reaction, the nitro group of the 2-chloro-3-nitrotoluene is reduced into amino group, and a benzene ring is dechlorinated, so that m-toluidine is synthesized. Therefore, the invention provides a new synthesis method, which widens the raw material source of m-toluidine on one hand, and has simpler process route on the other hand, thereby effectively reducing the three wastes generated in the synthesis process.
Further, 2-chloro-3-nitrotoluene and a metal catalyst are added into the reduction kettle, nitrogen is introduced into the reduction kettle to replace the gas in the reduction kettle, and when replacement is completed, hydrogen is introduced to carry out reduction reaction to synthesize m-toluidine.
Further, the method also comprises the following steps:
a reduction step: adding 2-chloro-3-nitrotoluene and a metal catalyst into a reduction kettle, introducing nitrogen into the reduction kettle for gas replacement, and introducing hydrogen for reduction reaction to synthesize a m-toluidine crude product when the gas replacement is finished;
a filter pressing step: separating the m-toluidine crude product from the metal catalyst;
washing, layering and dehydrating: washing the separated m-toluidine crude product, standing the m-toluidine crude product to obtain a layered m-toluidine crude product when washing is finished, and removing water from the layered m-toluidine crude product;
a rectification step: and distilling the dehydrated m-toluidine crude product under reduced pressure to obtain a m-toluidine pure product.
Further, the filter pressing step also comprises:
pressing the mixture of the m-toluidine crude product and the metal catalyst into a filter to separate the m-toluidine crude product and the metal catalyst;
blowing the separated metal catalyst back to the reduction kettle;
transferring the separated m-toluidine crude product into a buffer tank;
and introducing nitrogen into the buffer tank so as to enable the air pressure in the buffer tank to be micro-positive pressure.
Further, the washing, layering and dehydrating step further comprises the following steps:
pumping the separated m-toluidine crude product into a washing kettle, and injecting water into the washing kettle to wash the separated m-toluidine crude product;
when the washing is finished, standing the m-toluidine crude product in the washing kettle to obtain a layered m-toluidine crude product;
transferring the layered m-toluidine crude product into a dehydration kettle to remove moisture of the layered m-toluidine.
Further, in a washing kettle, the mass ratio of the separated m-toluidine crude product to water is 1: 1 to 10: 1, preferably 3:1 to 7: 1; in the dehydration kettle, the dehydration temperature is 100 ℃ to 110 ℃, preferably 105 ℃ to 110 ℃, and the vacuum degree is-0.06 MPa to-0.09 MPa, preferably-0.06 MPa to-0.08 MPa.
Further, the rectification step further comprises:
transferring the dehydrated m-toluidine crude product into a light component removal tower, and carrying out reduced pressure distillation to remove front cut fractions;
transferring the m-toluidine crude product without the front cut fraction into a rectifying tower, and carrying out reduced pressure distillation to obtain a m-toluidine pure product;
transferring the pure m-toluidine into a receiving tank, and adding triethanolamine into the receiving tank.
Further, in the rectifying tower, the tower top temperature is 80-110 ℃, preferably 90-100 ℃; in the rectifying tower, the vacuum degree is between-0.08 and-0.099 MPa, preferably between-0.09 and-0.099 MPa; the mass ratio of the triethanolamine to the m-toluidine pure product is 1: 1000 to 10: 1000, preferably 4: 1000 to 6: 1000.
further, the metal catalyst adopts one of a zinc catalyst, a nickel catalyst or a palladium carbon catalyst; the mass of the metal catalyst is 1% to 10%, preferably 3% to 10% of the mass of 2-chloro-3-nitrotoluene.
Further, the reaction temperature of the reduction reaction is 120 ℃ to 190 ℃, preferably 120 ℃ to 170 ℃, and the reaction pressure is 0.1Mpa to 2.0Mpa, preferably 0.75Mpa to 1.8 Mpa.
Compared with the prior art, the invention has the following advantages:
the invention provides a novel m-toluidine synthesis method, which widens the source of m-toluidine synthesis raw materials on one hand, and has simpler process route and effectively reduces three wastes generated in the synthesis process on the other hand.
In the implementation process of the method, the by-product industrial hydrochloric acid is generated, so that the method can be effectively adapted to the production of downstream products, and a new choice is provided for downstream products requiring industrial hydrochloric acid.
Drawings
FIG. 1: the overall flow chart.
Detailed Description
The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.
The first embodiment is as follows:
a synthetic method for synthesizing m-toluidine by 2-chloro-3-nitrotoluene through a one-step method comprises the following steps:
a reduction step:
1000kg of melted 2-chloro-3-nitrotoluene and 60kg of nickel catalyst are added into a reduction kettle. And introducing nitrogen into the reduction kettle to replace the gas in the reduction kettle, so that the reduction kettle is filled with the nitrogen. In the gas replacement process, an oxygen content detector is used for detecting the oxygen content in the reduction kettle. When the numerical value of the oxygen content reaches the qualified numerical value, stopping introducing the nitrogen, introducing the hydrogen into the reduction kettle, and replacing the nitrogen in the reduction kettle. At this time, the agitator was opened, and the circulating water and chilled water pipeline valves were adjusted. The temperature in the reduction kettle is controlled to be 135 ℃, and the reaction pressure is about 1.0 Mpa. The rotating speed of the stirrer is controlled to be 146 r/min. At this time, the hydrogen and 2-chloro-3-nitrotoluene are subjected to a reduction reaction at the temperature and the reaction pressure under the influence of a metal catalyst, so that the nitro group of the 2-chloro-3-nitrotoluene is reduced to an amino group, and the benzene ring is dechlorinated, thereby synthesizing a crude m-toluidine product. Sampling is carried out after the reaction is carried out for 13 hours, after the gas chromatography detection is qualified, the introduction of hydrogen is stopped, and nitrogen is introduced into the reduction kettle to replace the hydrogen.
A filter pressing step:
the mixture of the crude m-toluidine and the nickel catalyst in the reduction kettle is pressed into a filter by using 0.2Mpa of nitrogen, and the crude m-toluidine is separated from the nickel catalyst by using the filter. The separated nickel catalyst is blown back to the reduction kettle by nitrogen for continuous use. And transferring the separated m-toluidine crude product into a buffer tank, and introducing nitrogen into the buffer tank to ensure that the pressure in the buffer tank is slightly positive.
Washing, layering and dehydrating:
pumping the m-toluidine crude product in the buffer tank into a washing kettle, adding water into the washing kettle, and controlling the mass ratio of the m-toluidine crude product to the water to be 7: 1. The crude m-toluidine was stirred and washed for half an hour. After washing, the m-toluidine crude product in the washing kettle is allowed to stand for one hour, so that the m-toluidine crude product is precipitated and finally separated from water. Transferring the layered m-toluidine crude product into a dehydration kettle, starting jacket steam, controlling the temperature in the dehydration kettle at 105 ℃ and the vacuum degree at-0.08 Mpa to remove the water of the m-toluidine crude product.
A rectification step:
transferring the dehydrated m-toluidine crude product into a light component removal tower, and controlling the temperature at the top of the light component removal tower to be 85 ℃ for reduced pressure distillation. And when the reduced pressure distillation is finished, starting a reflux pump, and adjusting the reflux ratio to extract the front fraction after the reflux detection is qualified. And simultaneously, sampling and detecting the bottom of the light component removal tower, transferring the m-toluidine crude product without the front fraction into a rectifying tower after the detection is qualified, controlling the temperature at the top of the rectifying tower to be 96 ℃, and carrying out reduced pressure distillation under the vacuum degree of-0.094 Mpa to obtain main fraction m-toluidine, namely a pure m-toluidine product. Transferring the pure m-toluidine into a receiving tank, adding triethanolamine into the receiving tank, wherein the mass ratio of the triethanolamine to the pure m-toluidine is 4: 1000, so as to protect m-toluidine pure products from discoloration.
Example two:
a synthetic method for synthesizing m-toluidine by 2-chloro-3-nitrotoluene through a one-step method comprises the following steps:
a reduction step:
1000kg of melted 2-chloro-3-nitrotoluene and 30kg of palladium carbon catalyst are added into a reduction kettle. And introducing nitrogen into the reduction kettle to replace the gas in the reduction kettle, so that the reduction kettle is filled with the nitrogen. In the gas replacement process, an oxygen content detector is used for detecting the oxygen content in the reduction kettle. When the numerical value of the oxygen content reaches the qualified numerical value, stopping introducing the nitrogen, introducing the hydrogen into the reduction kettle, and replacing the nitrogen in the reduction kettle. At this time, the agitator was opened, and the circulating water and chilled water pipeline valves were adjusted. The temperature in the reduction kettle is controlled at 120 ℃, and the reaction pressure is 0.8 Mpa. The rotating speed of the stirrer is controlled to be 146 r/min. At this time, the hydrogen and 2-chloro-3-nitrotoluene are subjected to a reduction reaction at the temperature and the reaction pressure under the influence of a metal catalyst, so that the nitro group of the 2-chloro-3-nitrotoluene is reduced to an amino group, and the benzene ring is dechlorinated, thereby synthesizing a crude m-toluidine product. Sampling is carried out after the reaction is carried out for 10 hours, after the gas chromatography detection is qualified, the introduction of hydrogen is stopped, and nitrogen is introduced into the reduction kettle to replace the hydrogen.
A filter pressing step:
and (3) pressing the mixture of the m-toluidine crude product and the palladium-carbon catalyst in the reduction kettle into a filter by using 0.3Mpa of nitrogen, and separating the m-toluidine crude product from the palladium-carbon catalyst by using the filter. The separated palladium carbon catalyst is blown back to the reduction kettle by nitrogen for continuous use. And transferring the separated m-toluidine crude product into a buffer tank, and introducing nitrogen into the buffer tank to ensure that the pressure in the buffer tank is slightly positive.
Washing, layering and dehydrating:
pumping the m-toluidine crude product in the buffer tank into a washing kettle, adding water into the washing kettle, and controlling the mass ratio of the m-toluidine crude product to the water to be 3: 1. The crude m-toluidine was stirred and washed for half an hour. After washing, the m-toluidine crude product in the washing kettle is allowed to stand for one hour, so that the m-toluidine crude product is precipitated and finally separated from water. Transferring the layered m-toluidine crude product into a dehydration kettle, starting jacket steam, controlling the temperature in the dehydration kettle at 110 ℃ and the vacuum degree at-0.06 Mpa to remove the water in the m-toluidine crude product.
A rectification step:
transferring the dehydrated m-toluidine crude product to a lightness-removing column, and controlling the temperature at the top of the lightness-removing column to be 85 ℃ for reduced pressure distillation. And when the reduced pressure distillation is finished, starting a reflux pump, and adjusting the reflux ratio to extract the front fraction after the reflux detection is qualified. And simultaneously, sampling and detecting the bottom of the light component removal tower, transferring the m-toluidine crude product without the front fraction into a rectifying tower after the detection is qualified, controlling the temperature at the top of the rectifying tower to be 98 ℃, and carrying out reduced pressure distillation under the vacuum degree of-0.09 Mpa to obtain main fraction m-toluidine, namely a pure m-toluidine product. Transferring the pure m-toluidine into a receiving tank, adding triethanolamine into the receiving tank, wherein the mass ratio of the triethanolamine to the pure m-toluidine is 5: 1000, so as to protect m-toluidine pure products from discoloration.
Example three:
a synthetic method for synthesizing m-toluidine by 2-chloro-3-nitrotoluene through a one-step method comprises the following steps:
a reduction step:
1000kg of melted 2-chloro-3-nitrotoluene and 100kg of zinc catalyst are added into a reduction kettle. And introducing nitrogen into the reduction kettle to replace the gas in the reduction kettle, so that the reduction kettle is filled with the nitrogen. In the gas replacement process, an oxygen content detector is used for detecting the oxygen content in the reduction kettle. When the numerical value of the oxygen content reaches the qualified numerical value, stopping introducing the nitrogen, introducing the hydrogen into the reduction kettle, and replacing the nitrogen in the reduction kettle. At this time, the agitator was opened, and the circulating water and chilled water pipeline valves were adjusted. The temperature in the reduction kettle is controlled at 160 ℃, and the reaction pressure is 1.8 Mpa. The rotating speed of the stirrer is controlled to be 146 r/min. At this time, the hydrogen and 2-chloro-3-nitrotoluene are subjected to a reduction reaction at the temperature and the reaction pressure under the influence of a metal catalyst, so that the nitro group of the 2-chloro-3-nitrotoluene is reduced to an amino group, and the benzene ring is dechlorinated, thereby synthesizing a crude m-toluidine product. Sampling is carried out after the reaction is carried out for 19 hours, after the gas chromatography detection is qualified, the introduction of hydrogen is stopped, and nitrogen is introduced into the reduction kettle to replace the hydrogen.
A filter pressing step:
and (3) pressing the mixture of the crude m-toluidine and the zinc catalyst in the reduction kettle into a filter by using 0.3Mpa of nitrogen, and separating the crude m-toluidine from the zinc catalyst by using the filter. The separated zinc catalyst is blown back to the reduction kettle by nitrogen for continuous use. And transferring the separated m-toluidine crude product into a buffer tank, and introducing nitrogen into the buffer tank to ensure that the pressure in the buffer tank is slightly positive.
Washing, layering and dehydrating:
pumping the m-toluidine crude product in the buffer tank into a washing kettle, adding water into the washing kettle, and controlling the mass ratio of the m-toluidine crude product to the water to be 5: 1. The crude m-toluidine was stirred and washed for half an hour. After washing, the m-toluidine crude product in the washing kettle is allowed to stand for one hour, so that the m-toluidine crude product is precipitated and finally separated from water. Transferring the layered m-toluidine crude product into a dehydration kettle, starting jacket steam, controlling the temperature in the dehydration kettle at 108 ℃ and the vacuum degree at-0.07 Mpa to remove the water in the m-toluidine crude product.
A rectification step:
transferring the dehydrated m-toluidine crude product into a light component removal tower, and controlling the temperature at the top of the light component removal tower to be 85 ℃ for reduced pressure distillation. And when the reduced pressure distillation is finished, starting a reflux pump, and adjusting the reflux ratio to extract the front fraction after the reflux detection is qualified. And simultaneously, sampling and detecting the bottom of the light component removal tower, transferring the m-toluidine crude product without the front fraction into a rectifying tower after the detection is qualified, controlling the temperature at the top of the rectifying tower to be 90 ℃, and carrying out reduced pressure distillation under the vacuum degree of-0.097 Mpa to obtain main fraction m-toluidine, namely a pure m-toluidine product. Transferring the pure m-toluidine into a receiving tank, adding triethanolamine into the receiving tank, wherein the mass ratio of the triethanolamine to the pure m-toluidine is 6: 1000, so as to protect the m-toluidine pure product from discoloration.
In conclusion, the invention provides a novel m-toluidine synthesis method, which widens the raw material source of m-toluidine, and has the advantages of simpler process route, synthesis of a m-toluidine crude product in one step and effective reduction of three wastes generated in the production process. Meanwhile, in the reduction reaction, hydrogen chloride reaction waste gas generated after dechlorination of benzene rings of 2-chloro-3-nitrotoluene is absorbed by water in the washing, layering and dehydrating steps to generate hydrochloric acid as a byproduct. Therefore, the method can also be effectively matched with other downstream products.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
Claims (10)
1. A synthetic method for synthesizing m-toluidine by a 2-chloro-3-nitrotoluene one-step method is characterized by comprising the following steps: the method comprises the following steps: adding 2-chloro-3-nitrotoluene and a metal catalyst, and mixing hydrogen to perform a reduction reaction to synthesize m-toluidine.
2. The one-step synthesis method of m-toluidine by using 2-chloro-3-nitrotoluene according to claim 1, wherein: the method comprises the following steps: adding the 2-chloro-3-nitrotoluene and the metal catalyst into a reduction kettle, introducing nitrogen into the reduction kettle to replace the gas in the reduction kettle, and introducing the hydrogen to carry out reduction reaction to synthesize the m-toluidine when replacement is completed.
3. The one-step synthesis method of m-toluidine by using 2-chloro-3-nitrotoluene according to claim 1, wherein: further comprising the steps of:
a reduction step: adding the 2-chloro-3-nitrotoluene and the metal catalyst into a reduction kettle, introducing nitrogen into the reduction kettle for gas replacement, and introducing hydrogen for reduction reaction to synthesize a m-toluidine crude product when the gas replacement is finished;
a filter pressing step: separating the crude m-toluidine from the metal catalyst;
washing, layering and dehydrating: washing the separated m-toluidine crude product, standing the m-toluidine crude product to obtain a layered m-toluidine crude product when washing is finished, and removing water from the layered m-toluidine crude product;
a rectification step: and distilling the dehydrated m-toluidine crude product under reduced pressure to obtain a m-toluidine pure product.
4. The method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene in one step as claimed in claim 3, wherein: the filter pressing step further comprises:
pressing the mixture of the crude m-toluidine and the metal catalyst into a filter to separate the crude m-toluidine and the metal catalyst;
blowing the separated metal catalyst back to the reduction kettle;
transferring the separated m-toluidine crude product into a buffer tank;
and introducing nitrogen into the buffer tank so as to enable the air pressure in the buffer tank to be micro-positive pressure.
5. The method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene in one step as claimed in claim 3, wherein: the washing and layering dehydration step further comprises:
pumping the separated m-toluidine crude product into a washing kettle, and injecting water into the washing kettle to wash the separated m-toluidine crude product;
when washing is finished, standing the m-toluidine crude product in the washing kettle to obtain the layered m-toluidine crude product;
and transferring the layered m-toluidine crude product to a dehydration kettle to remove the moisture of the layered m-toluidine.
6. The method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene in one step as claimed in claim 5, wherein: in the washing kettle, the mass ratio of the separated m-toluidine crude product to water is 1: 1 to 10: 1;
in the dehydration kettle, the dehydration temperature is 100 ℃ to 110 ℃, and the vacuum degree is-0.06 Mpa to-0.09 Mpa.
7. The method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene in one step as claimed in claim 3, wherein: the rectification step further comprises:
transferring the dehydrated m-toluidine crude product into a light component removal tower, and carrying out reduced pressure distillation to remove front cut fraction;
transferring the m-toluidine crude product without the front cut fraction into a rectifying tower, and carrying out reduced pressure distillation to obtain the m-toluidine pure product;
transferring the pure m-toluidine product into a receiving tank, and adding triethanolamine into the receiving tank.
8. The method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene in one step as claimed in claim 7, wherein: in the rectifying tower, the tower top temperature is 80-110 ℃;
in the rectifying tower, the vacuum degree is between-0.08 MPa and-0.099 MPa;
the mass ratio of the triethanolamine to the pure m-toluidine product is 1: 1000 to 10: 1000.
9. the method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene as claimed in any one of claims 1 to 8, wherein: the metal catalyst adopts one of a zinc catalyst, a nickel catalyst or a palladium carbon catalyst;
the mass of the metal catalyst is 1 to 10 percent of the mass of the 2-chloro-3-nitrotoluene.
10. The method for synthesizing m-toluidine by using 2-chloro-3-nitrotoluene as claimed in any one of claims 1 to 8, wherein: the reaction temperature of the reduction reaction is 120 ℃ to 190 ℃, and the reaction pressure is 0.1MPa to 2.0 MPa.
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| GB859251A (en) * | 1958-09-17 | 1961-01-18 | Du Pont | A process for reducing organic nitro-compounds to amines and a catalyst for the same |
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