CN113979905A - Method for synthesizing liquid isopropyl methionine - Google Patents
Method for synthesizing liquid isopropyl methionine Download PDFInfo
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- CN113979905A CN113979905A CN202111593625.XA CN202111593625A CN113979905A CN 113979905 A CN113979905 A CN 113979905A CN 202111593625 A CN202111593625 A CN 202111593625A CN 113979905 A CN113979905 A CN 113979905A
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- 239000007788 liquid Substances 0.000 title claims abstract description 169
- SRMCAKWGHOOMDV-ZETCQYMHSA-N (2s)-4-methylsulfanyl-2-(propan-2-ylamino)butanoic acid Chemical compound CSCC[C@@H](C(O)=O)NC(C)C SRMCAKWGHOOMDV-ZETCQYMHSA-N 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 27
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 23
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 100
- 229930182817 methionine Natural products 0.000 claims abstract description 68
- FFEARJCKVFRZRR-BYPYZUCNSA-N L-methionine Chemical compound CSCC[C@H](N)C(O)=O FFEARJCKVFRZRR-BYPYZUCNSA-N 0.000 claims abstract description 66
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- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
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- 238000000066 reactive distillation Methods 0.000 claims description 27
- 239000003054 catalyst Substances 0.000 claims description 20
- 238000010992 reflux Methods 0.000 claims description 18
- 238000010533 azeotropic distillation Methods 0.000 claims description 14
- 230000002378 acidificating effect Effects 0.000 claims description 12
- 238000006460 hydrolysis reaction Methods 0.000 claims description 10
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 9
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- 230000007062 hydrolysis Effects 0.000 claims description 7
- 239000011347 resin Substances 0.000 claims description 7
- 229920005989 resin Polymers 0.000 claims description 7
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 6
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 6
- 239000003456 ion exchange resin Substances 0.000 claims description 6
- 229920003303 ion-exchange polymer Polymers 0.000 claims description 6
- 230000014759 maintenance of location Effects 0.000 claims description 6
- 238000005886 esterification reaction Methods 0.000 claims description 5
- SIWVGXQOXWGJCI-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;2-ethenylbenzenesulfonic acid Chemical compound C=CC1=CC=CC=C1C=C.OS(=O)(=O)C1=CC=CC=C1C=C SIWVGXQOXWGJCI-UHFFFAOYSA-N 0.000 claims description 3
- ZAFNJMIOTHYJRJ-UHFFFAOYSA-N Diisopropyl ether Chemical compound CC(C)OC(C)C ZAFNJMIOTHYJRJ-UHFFFAOYSA-N 0.000 claims description 3
- 238000010931 ester hydrolysis Methods 0.000 claims description 2
- 238000003786 synthesis reaction Methods 0.000 abstract description 7
- 238000002360 preparation method Methods 0.000 abstract description 4
- -1 Methionine hydroxy isopropyl ester Chemical class 0.000 description 21
- 239000000178 monomer Substances 0.000 description 19
- 239000013638 trimer Substances 0.000 description 19
- 150000002148 esters Chemical class 0.000 description 14
- 150000002741 methionine derivatives Chemical class 0.000 description 11
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- 230000002441 reversible effect Effects 0.000 description 5
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- 238000010189 synthetic method Methods 0.000 description 5
- 238000011084 recovery Methods 0.000 description 4
- KIYYUMANFSBVAV-MZIWDXLGSA-N (3r,3as,5ar,5br,7ar,9s,11ar,11br,13ar,13bs)-5a,5b,8,8,11a,13b-hexamethyl-3-propan-2-yl-1,2,3,3a,4,5,6,7,7a,9,10,11,11b,12,13,13a-hexadecahydrocyclopenta[a]chrysen-9-ol Chemical compound C([C@]1(C)[C@H]2CC[C@H]34)C[C@H](O)C(C)(C)[C@@H]1CC[C@@]2(C)[C@]4(C)CC[C@@H]1[C@]3(C)CC[C@@H]1C(C)C KIYYUMANFSBVAV-MZIWDXLGSA-N 0.000 description 3
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- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000000539 dimer Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000007086 side reaction Methods 0.000 description 3
- VWWOJJANXYSACS-UHFFFAOYSA-N 2-hydroxy-4-methylsulfanylbutanenitrile Chemical compound CSCCC(O)C#N VWWOJJANXYSACS-UHFFFAOYSA-N 0.000 description 2
- PICCHNWCTUUCAQ-UHFFFAOYSA-N 2-hydroxypentanethioic s-acid Chemical compound CCCC(O)C(O)=S PICCHNWCTUUCAQ-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 210000004767 rumen Anatomy 0.000 description 2
- YZUPZGFPHUVJKC-UHFFFAOYSA-N 1-bromo-2-methoxyethane Chemical compound COCCBr YZUPZGFPHUVJKC-UHFFFAOYSA-N 0.000 description 1
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- 238000000605 extraction Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C319/00—Preparation of thiols, sulfides, hydropolysulfides or polysulfides
- C07C319/14—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides
- C07C319/20—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides by reactions not involving the formation of sulfide groups
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C319/00—Preparation of thiols, sulfides, hydropolysulfides or polysulfides
- C07C319/26—Separation; Purification; Stabilisation; Use of additives
- C07C319/28—Separation; Purification
-
- 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
- Y02P20/10—Process efficiency
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- Chemical & Material Sciences (AREA)
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- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a method for synthesizing liquid isopropyl methionine, which comprises the following steps: (1) mixing liquid methionine and isopropanol to obtain a mixed raw material solution, introducing the mixed raw material solution into a reaction rectifying tower to obtain a mixed solution of isopropanol and water at the tower top, and obtaining a reaction tower kettle solution at the tower bottom; (2) mixing the mixed solution with an entrainer to obtain isopropanol and a ternary azeotrope, and carrying out two-phase separation on the ternary azeotrope to obtain an organic phase and a water phase; (3) carrying out reduced pressure rectification treatment on the reaction tower residue to obtain liquid isopropyl methionine and residual mixed liquor; (4) and (3) mechanically applying the residual mixed solution with the water phase separated in the step (2) to obtain a hydrolysate, mechanically applying the hydrolysate to the step (1), mechanically applying isopropanol in the step (2), supplementing liquid methionine, and carrying out continuous cycle production. The invention can be widely applied to the technical field of organic synthesis preparation.
Description
Technical Field
The application belongs to the technical field of organic synthesis preparation, and particularly relates to a synthesis method of liquid isopropyl methionine.
Background
Methionine hydroxy isopropyl ester (HMBI), also known as liquid isopropyl methionine, is a methionine analogue, is an isopropanol compound of the methionine hydroxy analogue, can be rapidly absorbed in rumen epithelium, thereby avoiding the degradation of microorganisms, has biological activity in rumen of 40% -58%, and is an ideal methionine additive for ruminants.
The existing synthesis process routes of liquid isopropyl methionine (D, L-2-hydroxy-4-methylthiobutyrate) have three types: 1) the D, L-2-hydroxy-4-methylthio butyrate is used as a raw material for preparation; 2) 2-hydroxy-4-methylthiobutyronitrile is used as a raw material for preparation, and a patent CN103534388B discloses a scheme for preparing D, L-2-hydroxy-4-methylthiobutyrate by using self-synthesized 2-hydroxy-4-methylthiobutyronitrile and alcohol (methanol, ethanol, isopropanol and isobutanol) as raw materials and concentrated sulfuric acid as a catalyst; 3) d, L-2-hydroxy-4-methylthiobutyric acid is used as a raw material, concentrated sulfuric acid, phosphoric acid or acidic resin is used as a catalyst, and is directly subjected to esterification reaction with alcohol to obtain the D, L-2-hydroxy-4-methylthiobutyric acid ester.
Patent US6660880B uses a third method, using isopropanol and liquid methionine as raw materials (68% monomer, 20% oligomer, 12% water), with an alcoholic-to-acid ratio of 2-10: 1, concentrated sulfuric acid or acidic resin Amberlyst15 is used as a catalyst, batch reaction is carried out at the reaction temperature of 80-100 ℃, and after 5 hours of reaction, the reaction product contains unreacted liquid methionine, unreacted isopropanol, liquid methionine monomer ester and liquid methionine oligomer ester. The reaction product is neutralized, distilled to remove water and alcohol, and rectified to obtain the monomer ester. The method separately introduces the catalyst, and needs neutralization and other treatment steps in the product purification process. In the process of recovering the byproduct stream or the heavy recycle stream mentioned in the examples, the reaction and the catalyst recovery steps still need to be carried out again, which is not beneficial to industrial continuous production.
Through the analysis of the prior art, the following problems exist: 1) the recovery process of heavy components (comprising liquid methionine monomer, dimer, trimer, liquid methionine monomer ester, dimer ester, trimer ester and the like) obtained in the reaction separation process is not completely discontinuous; 2) the catalyst introduced in the reaction process needs to be neutralized to remove the residual inorganic acid catalyst in the reaction liquid or filtered out in the post-treatment stage; 3) excess isopropanol during the reaction and low water utilization during the reaction.
Disclosure of Invention
The invention aims to solve the defects of the background technology and provides a synthetic method of liquid isopropyl methionine, which has low cost and can completely reuse heavy components in the reaction process.
Therefore, the invention provides a method for synthesizing liquid isopropyl methionine, which comprises the following steps:
(1) fully mixing liquid methionine and isopropanol to obtain a mixed raw material solution, continuously introducing the mixed raw material solution into a reaction rectifying tower, controlling the temperature and the pressure to perform esterification reaction, obtaining a mixed solution of isopropanol and water at the tower top of the reaction rectifying tower, and obtaining a reaction tower kettle solution at the tower bottom of the reaction rectifying tower;
(2) mixing the mixed liquid at the top of the reactive distillation tower in the step (1) with an entrainer, carrying out azeotropic distillation treatment to obtain isopropanol and a ternary azeotrope, and carrying out two-phase separation on the ternary azeotrope to obtain an organic phase and a water phase containing the isopropanol;
(3) carrying out reduced pressure rectification treatment on the reaction tower bottom liquid in the step (1), and controlling the temperature, the pressure and the reflux ratio to obtain liquid isopropyl methionine and residual mixed liquid;
(4) and (3) indiscriminately applying the mixed solution obtained in the step (3) to the water phase separated in the step (2) for ester hydrolysis to obtain a hydrolysate, indiscriminately applying the obtained hydrolysate to the step (1), recovering isopropanol indiscriminately applied in the step (2), supplementing liquid methionine, and carrying out continuous cycle production.
Preferably, in step (1), the molar ratio of isopropanol to liquid methionine is 2-4: 1.
Preferably, in the step (1), an acidic resin catalyst is arranged in the reactive distillation column, and the acidic resin catalyst is one or more of Amberlyst35 ion exchange resin, Amberlyst25 ion exchange resin and Amberlyst15 ion exchange resin.
Preferably, in the reactive distillation tower in the step (1), the reaction temperature is controlled to be 90-110 ℃, the pressure is controlled to be 60-100 kpa, the residence time is 3-8h, and the reflux ratio is 4-1: 1.
Preferably, in the reactive distillation column in the step (1), isopropanol vapor is continuously introduced into the reactive distillation column, the temperature of the isopropanol vapor is 100-130 ℃, and the isopropanol vapor is 0.4-0.7 times of the mass of the mixed raw material liquid.
Preferably, in the step (2), the azeotropic distillation is performed in an azeotropic distillation tower, the two-phase separation is performed in a two-phase separator, and the organic phase obtained by the two-phase separator is refluxed into the azeotropic distillation tower.
Preferably, in the step (2), the entrainer is one or more of toluene, isopropyl ether, ethylene glycol and benzene.
Preferably, in the step (3), the temperature is controlled to be 150-: 1.
preferably, in step (4), the hydrolysis of the remaining mixed liquor is carried out in a full mixed liquor reactor, and the amount of water used in step (2) is 5-30% of the volume of the remaining mixed liquor.
Preferably, in the step (4), the hydrolysis temperature is 100-140 ℃, and the retention time is 4-8 h.
The invention has the beneficial effects that:
(1) the invention provides a method for synthesizing liquid isopropyl methionine, which adopts an acidic catalyst fixed bed reactor, and the steps that isopropanol and liquid methionine are introduced into a reaction rectifying tower for reaction and rectification are omitted, so that the catalyst needs to be separated from reaction liquid, and the liquid methionine product obtained after rectification does not need to be washed.
(2) In the reaction rectification process of the method for synthesizing the liquid isopropyl methionine, superheated isopropanol vapor is introduced into the bottom of the reaction rectification tower, so that water in a reaction liquid phase is transferred into a gas phase, water produced in the reaction process and excessive isopropanol can be taken away in an accelerated manner, and the forward progress of an esterification reaction is promoted. The isopropanol and the water are separated from the mixture of the isopropanol and the water obtained from the top of the reactive distillation column through azeotropy and two-phase separation and are continuously used, so that the cost is saved.
(3) In the method for synthesizing the liquid isopropyl methionine, the residual mixed solution after reduced pressure rectification is applied mechanically to the water phase of the two-phase separator to generate reversible reaction for converting polymer ester into polymer, the obtained polymer can be applied mechanically continuously, so that the components of the overall reaction are constant, the generation of the liquid methionine polymer in the reaction process is reduced, and the stability of the reaction yield is improved. In the invention, heavy components in the reaction process can be completely recycled, so that the cost is saved, the recovery utilization rate is high, and the concept of energy conservation and environmental protection is met.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a schematic view of a liquid isopropyl methionine production apparatus of the present invention;
FIG. 2 is a reaction formula of liquid methionine monomer and isopropanol to form liquid methionine monomer ester according to the present invention;
FIG. 3 is a reaction formula of a liquid methionine monomer to form a liquid methionine dimer in the present invention;
FIG. 4 is a reaction formula of liquid methionine dimer and liquid methionine monomer to form liquid methionine trimer according to the present invention;
FIG. 5 is a schematic representation of the formation of a liquid methionine dimer ester with isopropanol in accordance with the present invention;
FIG. 6 is a schematic diagram showing the formation of a liquid methionine trimer ester from isopropyl alcohol in the present invention.
The symbols in the drawings illustrate that:
1. a mixing device; 2. a reactive distillation column; 3. an azeotropic distillation column; 4. a two-phase separator; 5. a vacuum rectification column; 6. a complete mixing flow reactor.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Example 1 a synthesis method of liquid isopropyl methionine, a synthesis device of liquid methionine for implementing the synthesis method described in this example, as shown in fig. 1, the synthesis device includes a mixing device 1, an azeotropic distillation column 3, a two-phase separator 4, a reactive distillation column 2, a vacuum distillation column 5 and a total mixed flow reactor 6, wherein the mixing device 1 includes but is not limited to a stirred tank.
Further, the reactive distillation tower 2 is provided with a distillation section, a reaction section and a stripping section from top to bottom in sequence. Wherein the reaction section is filled with an acidic resin catalyst which is Amberlyst35 ion exchange resin, the rectification section and the stripping section are filled with metal packing with the diameter of 3mm, the rectification section is provided with a reflux ratio controller, and the stripping section is provided with a reboiler.
The specific steps of the synthetic method of the liquid isopropyl methionine in the embodiment are as follows:
(1) liquid methionine 200g/h and isopropanol are fully mixed in a stirring kettle according to 144g/h to obtain brown clear and transparent mixed raw material liquid. Continuously introducing the obtained mixed raw material liquid into the upper part of a reaction section in a reaction rectifying tower 2, controlling the temperature of a tower kettle of the reaction rectifying tower 2 to be 90 ℃, the pressure to be 80kpa and the residence time to be 8h, continuously introducing 100 ℃ isopropanol steam into the lower part of the reaction section in the reaction rectifying tower 2, wherein the isopropanol steam is 0.4 time of the mass of the mixed raw material liquid, controlling the temperature of the tower top of the reaction rectifying tower 2 to be 74 ℃, controlling the reflux ratio of the tower top of the reaction rectifying tower 2 to be 5:5, obtaining a mixed liquid of isopropanol and water at the tower top of the reaction rectifying tower 2, the flow of the mixed liquid is about 350g/h, and the content of the isopropanol is about 87.4%; the bottom of the reactive distillation column 2 is used to obtain a reaction column bottom liquid, the main reaction in the reactive distillation column 2 is shown in fig. 2, and the side reactions are shown in fig. 3-6, i.e. the reaction column bottom liquid contains liquid isopropyl methionine, liquid methionine dimer, liquid methionine trimer, liquid methionine dimer ester and liquid methionine trimer ester.
(2) Introducing mixed liquid at the top of the reaction rectifying tower 2 into the middle of an azeotropic rectifying tower 3, introducing an azeotropic agent isopropyl ether into the upper part of the azeotropic rectifying tower 3, condensing and extracting a ternary azeotrope at the top of the azeotropic rectifying tower 3, separating the ternary azeotrope in a two-phase separator 4 to obtain an upper organic phase and a lower water phase, and refluxing the organic phase to the azeotropic rectifying tower 3; the isopropanol with the content of more than 99 percent is extracted from the tower bottom of the azeotropic distillation tower 3, the extracted flow is about 317g/h, 144g of the isopropanol is recycled to the stirring kettle, and the rest is recycled to the tower bottom of the reactive distillation tower 2.
(3) And (3) introducing all reaction tower bottoms into the middle part of a vacuum rectifying tower 5, carrying out vacuum rectification treatment, controlling the pressure to be 2.5kpa, the temperature to be 160 ℃, and the reflux ratio to be 6:3, and obtaining 231.02g of a clear and transparent product at the tower top of the vacuum rectifying tower 5, wherein the content of liquid isopropyl methionine is 97.21%, and the yield is 98.56%. 79.60g of dark brown residual mixed liquid is obtained at the bottom of the vacuum rectifying tower, and the main components of the mixed liquid are 52.9 percent of liquid methionine dimer isopropyl ester, 25.3 percent of liquid methionine trimer isopropyl ester, 3.88 percent of liquid methionine dimer, 5.16 percent of liquid methionine trimer and 8.65 percent of liquid methionine monomer isopropyl ester.
(4) And (3) introducing all the residual mixed liquor into a continuous full mixed liquor reactor 6, mechanically applying the water phase separated in the step (3), wherein the water amount mechanically applied in the step (3) is 5% of the volume of the residual mixed liquor, controlling the reaction temperature at 140 ℃ and the retention time at 8h, and performing hydrolysis reaction, namely performing reversible reaction on the liquid methionine dimer ester and the liquid methionine trimer ester to complete the conversion of the polymer ester to the monomer to obtain a hydrolysis product. And (3) recycling the hydrolysate to the stirring kettle in the step (1), recycling the isopropanol separated in the step (3), supplementing liquid methionine, and maintaining the molar ratio of the isopropanol to the liquid methionine to be 2:1 for continuous cycle production.
Example 2 a method for synthesizing liquid isopropyl methionine, an apparatus for synthesizing liquid methionine implementing the synthesis method described in this example was the same as in example 1, wherein Amberlyst25 ion exchange resin was used as the acidic catalyst.
The specific steps of the synthetic method of the liquid isopropyl methionine in the embodiment are as follows:
(1) liquid methionine 200g/h and isopropanol 286g/h are fully mixed in a stirring kettle to obtain brown clear transparent mixed raw material liquid. Continuously introducing the mixed raw material liquid into the upper part of a reaction section in a reaction rectifying tower 2, controlling the temperature of a tower kettle of the reaction rectifying tower 2 to be 110 ℃, the pressure to be 100kpa, isopropanol vapor to be 0.5 times of the mass of the mixed raw material liquid, keeping the residence time to be 3h, continuously introducing the isopropanol vapor of 120 ℃ into the lower part of the reaction section in the reaction rectifying tower 2, controlling the temperature of the tower top of the reaction rectifying tower 2 to be 80 ℃, controlling the reflux ratio of the tower top of the reaction rectifying tower 2 to be 12:3, obtaining a mixed liquid of isopropanol and water at the tower top of the reaction rectifying tower 2, wherein the flow of the mixed liquid is about 323g/h, and the content of the isopropanol is about 88%; the bottom of the reactive distillation column 2 is used to obtain a reaction column bottom liquid, the main reaction in the column of the reactive distillation column 2 is shown in fig. 2, and the side reactions are shown in fig. 3-6, i.e. the reaction column bottom liquid contains liquid isopropyl methionine, liquid methionine dimer, liquid methionine trimer, liquid methionine dimer ester and liquid methionine trimer ester.
(2) Introducing mixed liquid at the top of the reaction rectifying tower 2 into the middle of an azeotropic rectifying tower 3, introducing an entrainer glycol into the upper part of an azeotropic rectifying tower 6, condensing and extracting a ternary azeotrope at the top of the azeotropic rectifying tower 3, separating the ternary azeotrope in a two-phase separator 4 to obtain an upper organic phase and a lower water phase, and refluxing the organic phase to the azeotropic rectifying tower 3; the isopropanol with the content of more than 99 percent is extracted from the tower bottom of the azeotropic distillation tower 3, the extracted flow is about 323g/h, wherein 286g of the isopropanol is recycled to the stirring kettle, and the rest is recycled to the tower bottom of the reactive distillation tower 2.
(3) And (3) introducing all reaction tower bottoms into the middle part of a vacuum rectifying tower 5, carrying out vacuum rectification treatment, controlling the pressure to be 5kpa, the temperature to be 170 ℃, and the reflux ratio to be 9:3, and obtaining 241g/h of a clear and transparent product at the tower top of the vacuum rectifying tower 5, wherein the content of the liquid isopropyl methionine is 98.63%, and the yield is 98.72%. The bottom of the vacuum rectifying tower 5 obtains a dark brown residual mixed solution 69.23g/h, and the main components are 32.46 percent of liquid methionine dimer isopropyl ester, 22.54 percent of liquid methionine trimer isopropyl ester, 4.44 percent of liquid methionine monomer, 5.44 percent of liquid methionine dimer, 7.68 percent of liquid methionine trimer and 11.88 percent of liquid methionine monomer isopropyl ester.
(4) And (3) introducing all the residual mixed liquor into a continuous full mixed liquor reactor 6, mechanically applying the water phase separated in the step (2), wherein the water amount mechanically applied in the step (2) is 30% of the volume of the residual mixed liquor, controlling the reaction temperature at 120 ℃ and the retention time at 6h, and performing hydrolysis reaction, namely performing reversible reaction on the liquid methionine dimer ester and the liquid methionine trimer ester to complete the conversion of the polymer ester to the monomer to obtain a hydrolysis product. And (3) recycling the hydrolysate to the stirring kettle in the step (1), recycling the isopropanol separated in the step (2), supplementing liquid methionine, and maintaining the molar ratio of the isopropanol to the liquid methionine to be 4:1 for continuous cycle production.
Example 3 a method for synthesizing liquid isopropyl methionine, an apparatus for synthesizing liquid methionine implementing the synthesis method described in this example was the same as in example 1, wherein Amberlyst15 ion exchange resin was used as the acidic catalyst.
The specific steps of the synthetic method of the liquid isopropyl methionine in the embodiment are as follows:
(1) liquid methionine 200g/h and isopropanol 214g/h are fully mixed in a stirring kettle to obtain brown clear transparent mixed raw material liquid. Continuously introducing the obtained mixed raw material liquid into the upper part of a reaction section in a reaction rectifying tower 2, controlling the tower kettle temperature of the reaction rectifying tower 2 to be 100 ℃, the pressure to be 60kpa and the residence time to be 6 hours, continuously introducing 130 ℃ isopropanol steam into the lower part of the reaction section in the reaction rectifying tower 2, wherein the isopropanol steam is 0.7 time of the mass of the mixed raw material liquid, controlling the tower top temperature of the reaction rectifying tower 2 to be 68 ℃, controlling the tower top reflux ratio of the reaction rectifying tower 2 to be 6:3, obtaining a mixed liquid of isopropanol and water at the tower top of the reaction rectifying tower 2, the flow of the mixed liquid is about 324g/h, and the content of the isopropanol is about 87%; the bottom of the reactive distillation column 2 is used to obtain a reaction column bottom liquid, the main reaction in the column of the reactive distillation column 2 is shown in fig. 2, and the side reactions are shown in fig. 3-6, i.e. the reaction column bottom liquid contains liquid isopropyl methionine, liquid methionine dimer, liquid methionine trimer, liquid methionine dimer ester and liquid methionine trimer ester.
(2) Introducing mixed liquid at the top of the reaction rectifying tower 2 into the middle part of an azeotropic rectifying tower 3, introducing an entrainer toluene into the upper part of the azeotropic rectifying tower 3, condensing and extracting a ternary azeotrope at the top of the azeotropic rectifying tower 3, separating the ternary azeotrope in a two-phase separator 4 to obtain an upper organic phase and a lower water phase, and refluxing the organic phase to the azeotropic rectifying tower 3; the isopropanol with the content of more than 99 percent is extracted from the tower bottom of the azeotropic distillation tower 3, the extracted flow is about 285g/h, 214g of the isopropanol is recycled to the stirring kettle, and the rest is recycled to the tower bottom of the reactive distillation tower 2.
(3) And (3) introducing all reaction tower bottoms into the middle part of a vacuum rectifying tower 5, carrying out vacuum rectification treatment, controlling the pressure to be 0.5kpa, the temperature to be 150 ℃, and the reflux ratio to be 3:3, and obtaining 228.4g of a clear and transparent product at the tower top of the vacuum rectifying tower 5, wherein the content of the liquid isopropyl methionine is 99.4%, and the yield is 99.1%. 65.3g of dark brown residual mixed liquid is obtained at the bottom of the vacuum rectifying tower, and the main components of the mixed liquid are 48.72 percent of liquid methionine dimer isopropyl ester, 22.85 percent of liquid methionine tripolymer isopropyl ester, 0.74 percent of liquid methionine monomer, 0.91 percent of liquid methionine dimer, 3.94 percent of liquid methionine tripolymer and 2.89 percent of liquid methionine monomer isopropyl ester.
(4) And (3) introducing all the residual mixed liquor into a continuous full mixed liquor reactor 6, mechanically applying the water phase separated in the step (2), wherein the water amount mechanically applied in the step (2) is 27% of the volume of the residual mixed liquor, controlling the reaction temperature to be 100 ℃ and the retention time to be 4h, and performing hydrolysis reaction, namely performing reversible reaction on the liquid methionine dimer ester and the liquid methionine trimer ester to complete the conversion of the polymer ester to the monomer to obtain a hydrolysis product. And (3) recycling the hydrolysate to the stirring kettle in the step (1), recycling the isopropanol separated in the step (2), supplementing liquid methionine, and maintaining the molar ratio of the isopropanol to the liquid methionine to be 3:1 for continuous cycle production.
Comparative example 1 Synthesis of liquid isopropyl methionine with 95% concentrated sulfuric acid as catalyst
(1) In a three-neck flask, 0.2mol (34.98g) of liquid methionine with the mass fraction of 88 percent is added, 0.3 to 0.8mol (18.00 to 48.01 g) of isopropanol is added, 4.02g of 95 percent concentrated sulfuric acid is added, and the reaction is carried out for 2 hours at the temperature of 89 ℃.
(2) The three-necked flask was supplemented with 2.17 to 1.67mol (122.41 to 92.42 g) of isopropanol. Heating to reflux temperature with reflux ratio of 1, refluxing for 5min, and azeotropic distilling to obtain excessive isopropanol and water via azeotropic rectifying tower. Along with azeotropic extraction, the temperature of the tower kettle of the azeotropic distillation tower is raised to 95 ℃, and then the reaction is stopped. After the temperature is reduced to room temperature, sampling and testing are carried out, the content of the liquid isopropyl methionine in the reaction liquid is 43.90 percent, and the yield of the liquid isopropyl methionine is calculated to be 87.44 percent.
Comparative example 2 Amberlyst35 Synthesis of liquid isopropyl methionine by fixed bed reactive distillation
The reaction section used a 25mm diameter rectification column, 300mm in length, packed with 200ml Amberlyst35 catalyst. The rectifying section is filled with 3mm theta ring packing. Feeding isopropanol and 88% of liquid methionine according to the molar ratio of 2:1, wherein the flow rate is 26g/h, and feeding at the upper part of a rectifying section. The isopropanol is fed by saturated steam, the flow rate is 15.7g/h, and the feeding position is positioned at the bottom of the rectifying section. The reaction rectification adopts normal pressure operation, and after the operation is stable with the reflux ratio of 2:1, the reboiler at the bottom of the tower has the temperature of about 120 ℃ and the temperature at the top of the tower is about 80 ℃. The flow rate of the top of the tower is about 26.6g/h, and the flow rate of the bottom of the tower is about 15.1 g/h.
The content of liquid isopropyl methionine in the components extracted from the tower bottom is 62%, and the calculated yield is 53.95%. The isopropyl ester content of the liquid methionine dimer is about 12%, the monomer content of the liquid methionine is 18.8%, the dimer content of the liquid methionine is 4.5%, and the trimer content of the liquid methionine is 1.8%.
Here, it should be noted that the liquid methionine in examples 1-3 and comparative examples 1-2 was composed of 67% liquid methionine monomer, 16% liquid methionine dimer, 5% liquid methionine trimer and 12% water.
And (4) experimental conclusion:
as is clear from examples 1 to 3 and comparative example 1, the yield of liquid isopropyl methionine prepared by using the reactive distillation column containing an acidic catalyst in examples 1 to 3 of the present invention is significantly higher than that of liquid isopropyl methionine prepared by the conventional synthesis method.
As is clear from examples 1 to 3 and comparative example 2, the yield of liquid isopropyl methionine prepared by the synthesis method of examples 1 to 3 of the present invention could not be achieved even when the reactive distillation column containing the acidic catalyst was used alone.
In summary, the following steps: according to the synthetic method of the liquid isopropyl methionine, the isopropanol and the liquid methionine are introduced into the reaction rectifying tower to react and rectify, so that the step that a catalyst needs to be separated from reaction liquid is omitted, and the rectified liquid methionine product does not need to be washed. In addition, the mixture of isopropanol and water can be obtained at the top of the reaction rectifying tower, and the isopropanol and the water are separated through azeotropy and two-phase separation and are continuously recycled, so that the cost is saved.
In the reaction rectification process of the method for synthesizing the liquid isopropyl methionine, superheated isopropanol vapor is introduced into the bottom of the reaction rectification tower, so that water in a reaction liquid phase is transferred into a gas phase, water produced in the reaction process and excessive isopropanol can be taken away in an accelerated manner, and the forward progress of an esterification reaction is promoted. The isopropanol and the water are separated from the mixture of the isopropanol and the water obtained from the top of the reactive distillation column through azeotropy and two-phase separation and are continuously used, so that the cost is saved.
In the method for synthesizing the liquid isopropyl methionine, the residual mixed solution after the reduced pressure rectification is applied mechanically to the water phase of the two-phase separator to generate the reversible reaction of converting polymer ester to polymer, the obtained polymer can be applied mechanically continuously, so that all components of the whole reaction are constant, and the stability of the reaction yield is improved. In the invention, heavy components in the reaction process can be completely recycled, so that the cost is saved, the recovery utilization rate is high, and the concept of energy conservation and environmental protection is met.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. A method for synthesizing liquid isopropyl methionine is characterized by comprising the following steps:
(1) fully mixing liquid methionine and isopropanol to obtain a mixed raw material solution, continuously introducing the mixed raw material solution into a reaction rectifying tower, controlling the temperature and the pressure to perform esterification reaction, obtaining a mixed solution of isopropanol and water at the tower top of the reaction rectifying tower, and obtaining a reaction tower kettle solution at the tower bottom of the reaction rectifying tower;
(2) mixing the mixed liquid at the top of the reactive distillation tower in the step (1) with an entrainer, carrying out azeotropic distillation treatment to obtain isopropanol and a ternary azeotrope, and carrying out two-phase separation on the ternary azeotrope to obtain an organic phase and a water phase containing the isopropanol;
(3) carrying out reduced pressure rectification treatment on the reaction tower bottom liquid in the step (1), and controlling the temperature, the pressure and the reflux ratio to obtain liquid isopropyl methionine and residual mixed liquid;
(4) and (3) indiscriminately applying the mixed solution obtained in the step (3) to the water phase separated in the step (2) for ester hydrolysis to obtain a hydrolysate, indiscriminately applying the obtained hydrolysate to the step (1), recovering isopropanol indiscriminately applied in the step (2), supplementing liquid methionine, and carrying out continuous cycle production.
2. The method for synthesizing liquid isopropyl methionine according to claim 1, wherein: in the step (1), the molar ratio of the isopropanol to the liquid methionine is 2-4: 1.
3. The method for synthesizing liquid isopropyl methionine according to claim 1, wherein: in the step (1), an acidic resin catalyst is arranged in the reactive distillation tower, and the acidic resin catalyst is one or more of Amberlyst35 ion exchange resin, Amberlyst25 ion exchange resin and Amberlyst15 ion exchange resin.
4. The method for synthesizing liquid isopropyl methionine according to claim 1, wherein: in the reactive distillation tower in the step (1), the reaction temperature is controlled to be 90-110 ℃, the pressure is controlled to be 60-100 kpa, the retention time is 3-8h, and the reflux ratio is 4-1: 1.
5. The method for synthesizing liquid isopropyl methionine according to claim 1, wherein: and (2) in the reactive distillation tower in the step (1), continuously introducing isopropanol vapor into the reactive distillation tower, wherein the temperature of the isopropanol vapor is 100-130 ℃, and the isopropanol vapor is 0.4-0.7 time of the mass of the mixed raw material liquid.
6. The method for synthesizing liquid isopropyl methionine according to claim 1, wherein: in the step (2), the azeotropic distillation is carried out in an azeotropic distillation tower, the two-phase separation is carried out in a two-phase separator, and an organic phase obtained by the two-phase separator flows back to the azeotropic distillation tower.
7. The method for synthesizing liquid isopropyl methionine according to claim 1, wherein: in the step (2), the entrainer is one or more of toluene, isopropyl ether, ethylene glycol and benzene.
8. The method for synthesizing liquid isopropyl methionine according to claim 1, wherein: in the step (3), the temperature is controlled to be 150-: 1.
9. the method for synthesizing liquid isopropyl methionine according to claim 1, wherein: in the step (4), the hydrolysis of the residual mixed liquor is carried out in a full mixed liquor reactor, and the water amount in the step (2) is mechanically applied to be 5-30% of the volume of the residual mixed liquor.
10. The method for synthesizing liquid isopropyl methionine according to claim 1, wherein: in the step (4), the hydrolysis temperature is 100-140 ℃, and the retention time is 4-8 h.
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