CN110294675B - Method and system for preparing methyl acetoacetate by adopting tubular continuous flow reactor - Google Patents
Method and system for preparing methyl acetoacetate by adopting tubular continuous flow reactor Download PDFInfo
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- WRQNANDWMGAFTP-UHFFFAOYSA-N Methylacetoacetic acid Chemical compound COC(=O)CC(C)=O WRQNANDWMGAFTP-UHFFFAOYSA-N 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 33
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 155
- 239000003054 catalyst Substances 0.000 claims abstract description 77
- 238000006243 chemical reaction Methods 0.000 claims abstract description 66
- 150000002148 esters Chemical class 0.000 claims abstract description 56
- WASQWSOJHCZDFK-UHFFFAOYSA-N diketene Chemical compound C=C1CC(=O)O1 WASQWSOJHCZDFK-UHFFFAOYSA-N 0.000 claims abstract description 44
- 238000002156 mixing Methods 0.000 claims abstract description 34
- 230000001105 regulatory effect Effects 0.000 claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 claims abstract description 13
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000000126 substance Substances 0.000 claims abstract description 9
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 33
- UAOMVDZJSHZZME-UHFFFAOYSA-N diisopropylamine Chemical compound CC(C)NC(C)C UAOMVDZJSHZZME-UHFFFAOYSA-N 0.000 claims description 24
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims description 15
- 239000000376 reactant Substances 0.000 claims description 11
- 229940043279 diisopropylamine Drugs 0.000 claims description 8
- HPNMFZURTQLUMO-UHFFFAOYSA-N diethylamine Chemical compound CCNCC HPNMFZURTQLUMO-UHFFFAOYSA-N 0.000 claims description 7
- 230000003068 static effect Effects 0.000 claims description 4
- 238000001816 cooling Methods 0.000 abstract description 6
- 238000005086 pumping Methods 0.000 abstract description 4
- 238000010992 reflux Methods 0.000 abstract description 3
- 238000010923 batch production Methods 0.000 abstract description 2
- 238000012824 chemical production Methods 0.000 abstract description 2
- 238000000926 separation method Methods 0.000 abstract description 2
- 238000007086 side reaction Methods 0.000 abstract description 2
- 238000009835 boiling Methods 0.000 description 4
- HQABUPZFAYXKJW-UHFFFAOYSA-N butan-1-amine Chemical compound CCCCN HQABUPZFAYXKJW-UHFFFAOYSA-N 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- WGYKZJWCGVVSQN-UHFFFAOYSA-N propylamine Chemical compound CCCN WGYKZJWCGVVSQN-UHFFFAOYSA-N 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- 238000009833 condensation Methods 0.000 description 3
- 230000005494 condensation Effects 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 description 2
- UUIQMZJEGPQKFD-UHFFFAOYSA-N Methyl butyrate Chemical compound CCCC(=O)OC UUIQMZJEGPQKFD-UHFFFAOYSA-N 0.000 description 2
- 238000005886 esterification reaction Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000003128 rodenticide Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 239000005794 Hymexazol Substances 0.000 description 1
- XVOKUMIPKHGGTN-UHFFFAOYSA-N Imazethapyr Chemical compound OC(=O)C1=CC(CC)=CN=C1C1=NC(C)(C(C)C)C(=O)N1 XVOKUMIPKHGGTN-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 125000002490 anilino group Chemical group [H]N(*)C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- 239000003899 bactericide agent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229920003086 cellulose ether Polymers 0.000 description 1
- 239000012461 cellulose resin Substances 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 238000005112 continuous flow technique Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- BXNANOICGRISHX-UHFFFAOYSA-N coumaphos Chemical compound CC1=C(Cl)C(=O)OC2=CC(OP(=S)(OCC)OCC)=CC=C21 BXNANOICGRISHX-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- FHIVAFMUCKRCQO-UHFFFAOYSA-N diazinon Chemical compound CCOP(=S)(OCC)OC1=CC(C)=NC(C(C)C)=N1 FHIVAFMUCKRCQO-UHFFFAOYSA-N 0.000 description 1
- 125000001664 diethylamino group Chemical group [H]C([H])([H])C([H])([H])N(*)C([H])([H])C([H])([H])[H] 0.000 description 1
- CJHXCRMKMMBYJQ-UHFFFAOYSA-N dimethirimol Chemical compound CCCCC1=C(C)NC(N(C)C)=NC1=O CJHXCRMKMMBYJQ-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000032050 esterification Effects 0.000 description 1
- BBXXLROWFHWFQY-UHFFFAOYSA-N ethirimol Chemical compound CCCCC1=C(C)NC(NCC)=NC1=O BBXXLROWFHWFQY-UHFFFAOYSA-N 0.000 description 1
- 230000002363 herbicidal effect Effects 0.000 description 1
- 239000004009 herbicide Substances 0.000 description 1
- KGVPNLBXJKTABS-UHFFFAOYSA-N hymexazol Chemical compound CC1=CC(O)=NO1 KGVPNLBXJKTABS-UHFFFAOYSA-N 0.000 description 1
- 239000002917 insecticide Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- -1 pyrimidephos Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/46—Preparation of carboxylic acid esters from ketenes or polyketenes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
The invention belongs to the field of chemical production, and relates to a method and a system for preparing methyl acetoacetate by adopting a tubular continuous flow reactor. The method comprises the steps of respectively pumping methanol and a catalyst into a catalyst mixing section, mixing the methanol and the catalyst, starting a diketene metering pump, pumping diketene and an alcohol solution into a tubular continuous flow reactor, regulating the reaction pressure through a pressure regulating valve, cooling the crude ester after the reaction through a condenser, flowing into a buffer tank, refluxing low-boiling-point substances in the crude ester into the buffer tank after the low-boiling-point substances pass through the condenser, evacuating non-condensable gas, pumping the crude ester in the buffer tank into a rectifying tower through the metering pump, and rectifying the crude ester to obtain the methyl acetoacetate product. Compared with the traditional batch process, the method has the advantages that the reaction residence time is greatly shortened, thereby reducing the generation of side reactions, improving the yield and content of products, further reducing the difficulty of rectification separation, reducing the production cost and greatly reducing the safety risk of production.
Description
Technical Field
The invention belongs to the field of chemical production, and particularly relates to a method and a system for preparing methyl acetoacetate by adopting a tubular continuous flow reactor.
Background
Methyl acetoacetate, alias: methyl butanoate; methyl acetoacetate; english name: methyl acetoacetate; appearance properties: colorless liquid, having a very bad smell; solubility: is easy to dissolve in water; the molecular formula is C5H8O3; molecular weight 116.12; melting point (. Degree. C.): -28 ℃; density (g/ml, 25/4 ℃): 1.077. the methyl acetoacetate is mainly applied to the medical industry and is an intermediate of bactericide hymexazol, dimethirimol, ethirimol, insecticide diazinon, coumaphos, pyrimidephos, herbicide imazethapyr, rodenticide, rodenticide and the like. It can also be used as the component of the solvent of cellulose ether and the mixed solvent of cellulose resin, and also used in the organic synthesis of pesticides, medicines, dyes, high polymer stabilizers, etc. The synthesis process in the prior art comprises the following steps:
the traditional methyl acetoacetate preparation process adopts an intermittent kettle reaction, firstly, methanol and a catalyst are mixed, then the temperature is raised to reflux of the methanol, then diketene is dripped according to a certain proportion, the dripping time is 3-4h, the temperature of reaction liquid is raised to 100-110 ℃ after dripping, the temperature is kept for 0.5-1 h, and after the crude ester is cooled, the crude ester is subjected to negative pressure rectification, so that a finished methyl acetoacetate product is prepared. Because of the long reaction time of the batch process, the diketene is extremely easy to self-polymerize at a higher temperature, the reaction yield is low, the selectivity is poor, and the safety risk of the process is high from the safety aspect. Therefore, the invention develops a continuous flow reaction process of methyl acetoacetate, a tubular continuous flow reactor is adopted, the equipment space occupation rate is low, the production cost investment is low, a spiral mixing piece is arranged in the reactor, diketene and alcohol can be fully mixed in the reactor, the reaction residence time is short, the yield and the content of methyl acetoacetate are higher, the continuous flow reaction belongs to a plug flow reaction, the back mixing is small, and the safety coefficient of the process is higher.
The publication number is CN105384631, and the name is a continuous methyl acetoacetate production process. The production process of methyl acetoacetate includes separating esterification kettle into heat insulating bin and cooling bin, spreading coarse ester, dropping methanol and diketene into the cooling bin, pressurizing the cooling bin, overflowing the product to the heat insulating bin via overflow pipe, dropping diketene into the overflow port, pumping the heat insulating bin to the rectifying tower to obtain the product. The disadvantage of this process is: 1) The diketene is dropwise added twice, and the molar ratio of the reaction is difficult to accurately control; 2) After a certain amount of accumulation in the thermal insulation bin, the thermal insulation bin is discharged by a pump, so that the retention time of materials is greatly prolonged, the thermal insulation bin is a semi-continuous process, and products are easy to decompose at a higher temperature, so that the product yield is reduced.
Publication number CN103864616 A2), entitled a process for the preparation of methyl acetoacetate. The invention discloses a method for preparing methyl acetoacetate, which comprises the steps of continuously adding diketene and methanol from a raw material port, continuously adding an extracting agent from an extraction port, simultaneously adding two materials into a reactive extraction rectifying tower, carrying out total reflux reaction, obtaining mixed liquid of methyl acetoacetate and the extracting agent at the tower bottom, and discharging methanol from the tower top, wherein the product yield is 95% and the content is 99.3%. The process has the defects that the extraction agent is introduced into a reaction system, the separation difficulty of products is increased, the operation difficulty is high, the production cost is increased, and the yield and the content of the products are slightly low.
Disclosure of Invention
In order to solve the problems described above, an object of the present invention is to provide a method and system for preparing methyl acetoacetate using a tubular continuous flow reactor.
The invention researches a process for preparing methyl acetoacetate by adopting a tubular continuous flow reactor, after premixing methanol and a catalyst, fully mixing the diketene and the diketene in the tubular reactor, and carrying out continuous esterification reaction under certain pressure and temperature.
The technical scheme of the invention is as follows:
a method for preparing methyl acetoacetate by using a tubular continuous flow reactor, which is characterized in that: the method comprises the following steps:
firstly, methanol and a catalyst are respectively pumped into a catalyst mixing section from a methanol metering tank and a catalyst metering tank through metering pumps according to certain proportion of flow, after the methanol and the catalyst are mixed, a diketene metering pump is started, diketene and an alcohol solution are pumped into a tubular continuous flow reactor according to certain flow, the reaction temperature is 50-150 ℃, the reaction residence time is 0.5-60 min, the reaction pressure is regulated by a pressure regulating valve and is 0-1 MPa, after the reaction, crude ester is cooled to 30-65 ℃ by a condenser, then flows into a buffer tank, low-boiling-point substances in the crude ester are returned to the buffer tank after passing through the condenser, noncondensable gas is emptied, the crude ester in the buffer tank is pumped into a rectifying tower through the metering pump, and the crude ester is rectified to obtain methyl acetoacetate;
the mol ratio of the diketene to the methanol is as follows: 1:1 to 1.4;
the dosage of the catalyst accounts for 0.03-2% of the total mass of the reactants;
the catalyst is one or more selected from propylamine, butylamine, diethylamine, triethylamine, diethylenetriamine, aniline and diisopropylamine.
According to the method for preparing methyl acetoacetate by adopting the tubular continuous flow reactor, the content of the methyl acetoacetate product obtained by the method is 99.7-99.9%, and the product yield is 98.8-99.0%.
Further, the molar ratio of the diketene to the methanol is as follows: 1:1.01-1.2.
Further, the catalyst accounts for 0.05 to 1.5 percent of the total mass of the reactants.
Further, the catalyst is selected from one or more of diethylamine, triethylamine, aniline and diisopropylamine.
According to the method for preparing methyl acetoacetate by adopting the tubular continuous flow reactor, the internal mixing element unit structure of the tubular continuous flow reactor is one of SV type, SK type, SX type, SH type and SL type.
According to the method for preparing methyl acetoacetate by adopting the tubular continuous flow reactor, the reaction temperature is 55-135 ℃; the residence time ranges from 6 minutes to 45 minutes; the reaction pressure ranges from 0.02MPa to 0.5MPa; the cooling temperature of the crude ester ranges from 35 to 55 ℃.
The invention also provides a system for preparing methyl acetoacetate by using the tubular continuous flow reactor, the method for preparing methyl acetoacetate by using the tubular continuous flow reactor can be applied to the system,
the system comprises a methanol metering tank 1, wherein the methanol metering tank 1 and a catalyst metering tank 6 are connected with an inlet of a catalyst mixing section 7, a methanol metering pump 4 is arranged between the methanol metering tank 1 and the catalyst mixing section 7, and a catalyst metering pump 5 is arranged between the catalyst metering tank 6 and the catalyst mixing section 7; the outlet of the catalyst mixing section 7 is connected with the inlet of the tubular continuous flow reactor 8 of the diketene metering tank 2, and a diketene metering pump 3 is arranged between the diketene metering tank 2 and the reaction section 8; the outlet of the reaction section 8 is sequentially connected with a pressure regulating valve 9, a crude ester condenser 10, a crude ester buffer tank 12 and a crude ester knockout pump 13; a condenser 11 is provided above the crude ester buffer tank 12.
Detailed description of the invention:
the invention mainly aims at the problems of overlong reaction time, high safety risk, low product yield and content and the like in the existing methyl acetoacetate preparation process, and develops a process for preparing methyl acetoacetate by adopting a tubular continuous flow reactor, wherein the reaction system is shown in figure 1, the reaction flow is shown in figure 2, and the specific operation steps are as follows:
firstly, methanol and a catalyst are respectively pumped into a catalyst mixing section 7 from a methanol metering tank 1 and a catalyst metering tank 6 according to certain proportion of flow through metering pumps 4 and 5, after the methanol and the catalyst are mixed, a diketene metering pump 3 is started, diketene and an alcohol solution are pumped into a tubular continuous flow reactor 8 according to certain flow, the reaction temperature is 50-150 ℃, the reaction residence time is 0.5-60 min, the reaction pressure is regulated by a pressure regulating valve 9, the reaction pressure is 0-1 MPa, crude ester is cooled to 30-65 ℃ by a condenser 10 after the reaction, then flows into a buffer tank 12, low-boiling-point substances in the crude ester are returned to the buffer tank 12 after the condenser 11, noncondensable gas is exhausted, the crude ester in the buffer tank 12 is pumped into a rectifying tower through a metering pump 13, the product content is 99.7-99.9% after the crude ester is rectified, and the product yield is 98.8-99.0%.
1) The mol ratio of the diketene to the methanol is as follows: 1:1 to 1.4, preferably 1:1.01 to 1.2;
2) The dosage of the catalyst accounts for 0.03 to 2 percent of the total mass of the reactants, and is preferably 0.05 to 1.5 percent;
3) The catalyst is one or more of propylamine, butylamine, diethylamine, triethylamine, diethylenetriamine, aniline and diisopropylamine, preferably diethylamine, triethylamine, aniline and diisopropylamine;
4) The internal mixing element unit structure of the tubular reactor is one of SV type, SK type, SX type, SH type and SL type, wherein the SV type unit is a cylinder assembled by corrugated plates with certain specification; the SK type unit is formed by assembling and welding spiral slices twisted left and right of a single pore canal; the SX-shaped units are formed into a plurality of X-shaped units by crossed cross bars according to a certain rule; the SH type unit consists of double pore channels, spiral sheets are placed in the pore channels, and the directions of the double pore channels of the adjacent units are staggered by 90 degrees; the SL units are formed into single X-shaped units by crossed cross bars according to a certain rule;
5) Preferably, the reaction temperature ranges from 55 to 135 ℃; the residence time ranges from 6 minutes to 45 minutes; the reaction pressure ranges from 0.02MPa to 0.5MPa; the cooling temperature of the crude ester ranges from 35 to 55 ℃.
The tubular reactor is in the prior art, the internal mixing part structure of the tubular reactor is a static mixer, the static mixer means that no moving element exists in a pipeline, only a static element exists in the pipeline, the tubular reactor can be classified into sv type, SK type and the like, and specific structures can be obtained by inquiring keywords.
The reaction system of the invention consists of 13 parts: 1 is a methanol metering tank, 2 is a diketene metering tank, 3 is a diketene metering pump, 4 is a methanol metering pump, 5 is a catalyst metering pump, 6 is a catalyst metering tank, 7 is a catalyst mixing section, 8 is a tubular continuous flow reactor, 9 is a pressure regulating valve, 10 is a crude ester condenser, 11 is a permeable air condenser, 12 is a crude ester buffer tank, and 13 is a crude ester material pump.
The invention has the beneficial technical effects that:
1) The intermittent process is changed into a continuous flow process, so that the reaction time is shortened, the generation of side reactions is reduced, and the yield and the content of methyl acetoacetate are improved (the content of a product is more than 99.7 percent, and the yield of the product is more than 98.8 percent);
2) The whole process is continuous operation from the mixing of the raw materials and the catalyst to the mixing reaction of the raw materials and the rectification of the crude ester, and the process operation is simpler;
3) Compared with batch reaction, the method adopts the tubular continuous flow reactor to prepare the methyl acetoacetate, has small space occupation rate of equipment and lower safety risk.
Drawings
FIG. 1 is a diagram of a reaction system for preparing methyl acetoacetate using a tubular continuous flow reactor;
FIG. 2 is a flow chart of a process for preparing methyl acetoacetate using a tubular continuous flow reactor.
Wherein: 1-methanol metering tank, 2-dk metering tank, 3-dk metering pump, 4-methanol metering pump, 5-catalyst metering pump, 6-catalyst metering tank, 7-catalyst mixing section, 8-tubular continuous flow reactor, 9-pressure regulating valve, 10-crude ester condenser, 11-permeable air condenser, 12-crude ester buffer tank and 13-crude ester pump.
Detailed Description
The invention is further illustrated below in connection with examples, which are to be understood by those skilled in the art as being illustrative only and not limiting in any way.
Example 1:
a method for preparing methyl acetoacetate by using a tubular continuous flow reactor, which comprises the following steps: firstly, methanol and a catalyst are respectively injected into a catalyst mixing section 7 from a methanol metering tank 1 and a catalyst metering tank 6 according to the flow rates of a certain proportion through metering pumps 4 and 5, after the methanol and the catalyst are mixed, a diketene metering pump 3 is started, diketene and an alcohol solution are injected into a tubular continuous flow reactor 8 according to the flow rates, the unit structure of the mixing part in the tubular reactor is SV, the mol ratio of diketene to the methanol is 1:1.01, the catalyst is diethylamine, the catalyst is 0.05% of the total mass of reactants, the reaction temperature is 55 ℃, the reaction residence time is 45min, the reaction pressure is regulated through a pressure regulating valve 9, the reaction pressure is 0.02MPa, after the reaction, crude ester is cooled to 35 ℃ through a condenser 10 and then flows into a buffer tank 12, low boiling matters in the crude ester flow back to the buffer tank 12 after the condensation pump 11, the non-condensable gas is emptied, the crude ester in the buffer tank 12 is injected into a rectifying tower through 13, the content of the crude ester is 99.7% after the rectification, and the product yield is 98.8%.
Example 2:
a method for preparing methyl acetoacetate by using a tubular continuous flow reactor, which comprises the following steps: firstly, methanol and a catalyst are respectively injected into a catalyst mixing section 7 from a methanol metering tank 1 and a catalyst metering tank 6 according to the flow of a certain proportion through metering pumps 4 and 5, after the methanol and the catalyst are mixed, a diketene metering pump 3 is started, diketene and an alcohol solution are injected into a tubular continuous flow reactor 8 according to a certain flow, the internal mixing element unit structure of the tubular reactor is SX-type, the mol ratio of diketene to the methanol is 1:1.04, the catalyst is triethylamine, the catalyst is used for 0.1 percent of the total mass of the reactants, the reaction temperature is 105 ℃, the reaction residence time is 10min, the reaction pressure is regulated through a pressure regulating valve 9, the reaction pressure is 0.3MPa, after the reaction, crude ester is cooled to 40 ℃ through a condenser 10, and then flows into a buffer tank 12, low-boiling substances in the crude ester flow back to the buffer tank 12 after the condensation of the crude ester is emptied through a buffer tank 12, the crude ester is injected into a rectifying tower through the buffer tank 13, the content of the crude ester is 99.8 percent after the rectification, and the product yield is 98.9 percent.
Example 3:
a method for preparing methyl acetoacetate by using a tubular continuous flow reactor, which comprises the following steps: firstly, methanol and a catalyst are respectively injected into a catalyst mixing section 7 from a methanol metering tank 1 and a catalyst metering tank 6 according to the flow of a certain proportion through metering pumps 4 and 5, after the methanol and the catalyst are mixed, a diketene metering pump 3 is started, diketene and an alcohol solution are injected into a tubular continuous flow reactor 8 according to a certain flow, the unit structure of the mixed part in the tubular reactor is SH, the mol ratio of diketene to the methanol is 1:1.1, the catalyst is aniline, the dosage of the catalyst accounts for 0.2% of the total mass of reactants, the reaction temperature is 120 ℃, the reaction residence time is 20min, the reaction pressure is regulated through a pressure regulating valve 9, the reaction pressure is 0.2MPa, after the reaction, crude ester is cooled to 45 ℃ through a condenser 10 and then flows into a buffer tank 12, low boiling substances in the crude ester are returned to the buffer tank 12 after being injected into a rectifying tower through a metering pump 13, the crude ester in the buffer tank 12 is emptied through non-condensable gas, the content of 99.7%, and the product yield is 99.0%.
Example 4:
a method for preparing methyl acetoacetate by using a tubular continuous flow reactor, which comprises the following steps: firstly, methanol and a catalyst are respectively injected into a catalyst mixing section 7 from a methanol metering tank 1 and a catalyst metering tank 6 according to the flow of a certain proportion through metering pumps 4 and 5, after the methanol and the catalyst are mixed, a diketene metering pump 3 is started, diketene and an alcohol solution are injected into a tubular continuous flow reactor 8 according to a certain flow, the unit structure of the mixing part in the tubular reactor is SL, the mol ratio of diketene to the methanol is 1:1.2, the catalyst is diisopropylamine, the dosage of the catalyst accounts for 1% of the total mass of reactants, the reaction temperature is 135 ℃, the reaction residence time is 6min, the reaction pressure is regulated through a pressure regulating valve 9, the reaction pressure is 0.5MPa, after the reaction, crude ester is cooled to 55 ℃ through a condenser 10 and then flows into a buffer tank 12, low boiling matters in the crude ester flow back to the buffer tank 12 after the condensation pump 11, the non-condensable gas is emptied, the crude ester in the buffer tank 12 is injected into a rectifying tower through 13, the content of the crude ester is 99.9% after the rectification, and the product yield is 99.0%.
Example 4:
a method for preparing methyl acetoacetate by using a tubular continuous flow reactor, which comprises the following steps: firstly, methanol and a catalyst are respectively injected into a catalyst mixing section 7 from a methanol metering tank 1 and a catalyst metering tank 6 through metering pumps 4 and 5 according to certain proportion of flow, after the methanol and the catalyst are mixed, a diketene metering pump 3 is started, diketene and an alcohol solution are injected into a tubular continuous flow reactor 8 according to certain flow, the unit structure of a mixing part in the tubular reactor is of SH type, the mol ratio of the diketene to the methanol is 1:1.2, the catalyst is a mixture of triethylamine and diisopropylamine, and the mixing proportion is m (triethylamine): m (diisopropylamine) =1: 1, the catalyst accounts for 0.5% of the total mass of reactants, the reaction temperature is 115 ℃, the reaction residence time is 25min, the reaction pressure is regulated by a pressure regulating valve 9, the reaction pressure is 0.1MPa, the crude ester is cooled to 55 ℃ by a condenser 10 after the reaction and flows into a buffer tank 12, low-boiling-point substances in the crude ester flow back to the buffer tank 12 after passing through the condenser 11, noncondensable gas is exhausted, the crude ester in the buffer tank 12 is pumped into a rectifying tower by a metering pump 13, the content of the product is 99.8% after the crude ester is rectified, and the product yield is 98.8%.
Example 5:
a method for preparing methyl acetoacetate by using a tubular continuous flow reactor, which comprises the following steps: firstly, methanol and a catalyst are respectively injected into a catalyst mixing section 7 from a methanol metering tank 1 and a catalyst metering tank 6 through metering pumps 4 and 5 according to certain proportion of flow, after the methanol and the catalyst are mixed, a diketene metering pump 3 is started, diketene and an alcohol solution are injected into a tubular continuous flow reactor 8 according to certain flow, the internal mixing element unit structure of the tubular reactor is of an SX type, the mol ratio of the diketene to the methanol is 1:1.1, the catalyst is a mixture of aniline, diethylamine and triethylamine, and the mixing proportion is m (aniline): m (diethylamine): m (triethylamine) =1: 1:1, the catalyst accounts for 0.3 percent of the total mass of reactants, the reaction temperature is 120 ℃, the reaction residence time is 22min, the reaction pressure is regulated by a pressure regulating valve 9, the reaction pressure is 0.3MPa, the crude ester is cooled to 45 ℃ by a condenser 10 after the reaction and flows into a buffer tank 12, low-boiling-point substances in the crude ester flow back to the buffer tank 12 after passing through the condenser 11, noncondensable gas is exhausted, the crude ester in the buffer tank 12 is pumped into a rectifying tower by a metering pump 13, the content of the product is 99.9 percent after the crude ester is rectified, and the product yield is 98.9 percent.
The present invention has been described in terms of preferred embodiments, but not limited thereto, and equivalents or alternatives thereof are contemplated as falling within the scope of the present invention.
Claims (5)
1. A method for preparing methyl acetoacetate by using a tubular continuous flow reactor, which is characterized in that: the method comprises the following steps:
firstly, methanol and a catalyst are respectively pumped into a catalyst mixing section from a methanol metering tank and a catalyst metering tank through metering pumps according to certain proportion of flow, after the methanol and the catalyst are mixed, a diketene metering pump is started, diketene and an alcohol solution are pumped into a tubular continuous flow reactor according to certain flow, the reaction temperature range is 55-135 ℃, the residence time range is 6-45 min, the reaction pressure is regulated by a pressure regulating valve and is 0.02-0.5 MPa, after the reaction, crude ester is cooled to 35-55 ℃ by a condenser and flows into a buffer tank, low-boiling-point substances in the crude ester flow back to the buffer tank through the condenser, noncondensable gas is exhausted, the crude ester in the buffer tank is pumped into a rectifying tower through the metering pump, and the crude ester is rectified to obtain methyl acetoacetate;
the mol ratio of the diketene to the methanol is as follows: 1:1.01-1.2;
the dosage of the catalyst accounts for 0.03-2% of the total mass of the reactants;
the catalyst is selected from one or more of diethylamine, triethylamine, aniline and diisopropylamine;
the internal mixing element structure of the tubular continuous flow reactor is a static mixer.
2. A process for preparing methyl acetoacetate using a tubular continuous flow reactor according to claim 1, wherein: the methyl acetoacetate product obtained by the method has the content of 99.7-99.9% and the product yield of 98.8-99.0%.
3. A process for preparing methyl acetoacetate using a tubular continuous flow reactor according to claim 1, wherein: the dosage of the catalyst accounts for 0.05 to 1.5 percent of the total mass of the reactants.
4. A process for preparing methyl acetoacetate using a tubular continuous flow reactor according to claim 1, wherein: the catalyst is selected from triethylamine.
5. A process for preparing methyl acetoacetate using a tubular continuous flow reactor according to claim 1, wherein: the internal mixing element unit structure of the tubular continuous flow reactor is one of SV type, SK type, SX type, SH type and SL type.
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| CN112409165A (en) * | 2020-11-06 | 2021-02-26 | 山东汇海医药化工有限公司 | Method for recovering ethyl acetoacetate distillation head |
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