CN113880715A - Purification method for electrochemically synthesizing dimethyl sebacate - Google Patents

Purification method for electrochemically synthesizing dimethyl sebacate Download PDF

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CN113880715A
CN113880715A CN202111169306.6A CN202111169306A CN113880715A CN 113880715 A CN113880715 A CN 113880715A CN 202111169306 A CN202111169306 A CN 202111169306A CN 113880715 A CN113880715 A CN 113880715A
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dimethyl sebacate
rectification
tower
purification
crude
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CN113880715B (en
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栾谨鑫
杜旺明
钱向阳
张永振
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Wanhua Chemical Group Co Ltd
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    • 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
    • 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
    • C07C67/62—Use of additives, e.g. for stabilisation

Abstract

The invention provides a purification method for electrochemically synthesizing dimethyl sebacate. The method comprises the steps of adding 2, 6-di-tert-butyl-1, 4-benzoquinone and magnesium formate into a crude product of electrochemically synthesized dimethyl sebacate, and obtaining the dimethyl sebacate through decompression and hypergravity rectification to complete separation and purification. The purification method can solve the problems of low product purity, large acid value, low rectification yield and easy polymerization of heavy components in the tower bottom in the traditional rectification and purification process, has the advantages of simple process and low energy consumption, and is suitable for wide industrial application.

Description

Purification method for electrochemically synthesizing dimethyl sebacate
Technical Field
The invention relates to a purification method for electrochemically synthesizing dimethyl sebacate, in particular to a mode for realizing the purification of dimethyl sebacate through salt effect and hypergravity rectification.
Background
Dimethyl sebacate is a plasticizer, a lubricant and a diluent of the lubricant in the wide plastic industry, can be used as a plasticizer, a softener and a solvent of cellulose resin, vinyl resin and synthetic rubber, is widely used as a main raw material for producing light stabilizers UV-770, UV-750, UV-123 and the like, is used as a solvent and a plasticizer of cellulose and vinyl resin, and can also be used as an intermediate of organic synthesis.
Adipic acid is used as a raw material to be esterified to synthesize adipate compounds, then Brown-Walker electrolytic decarboxylation coupling is carried out to synthesize sebacate compounds, and then hydrolysis is carried out to obtain sebacic acid. For example, the following technical scheme is disclosed in the document 'preparation of sebacic acid from adipic acid. Liaoning chemical industry, 1981(03): 66-67':
esterification of adipic acid to monomethyl adipate:
HOOC(CH2)4COOH+CH3OH→CH3OOC(CH2)4COOH+H2O
decarboxylation coupling of monomethyl adipate to dimethyl sebacate:
2CH3OOC(CH2)4COOH→CH3OOC(CH2)8COOCH3+H2+2CO2
hydrolysis of dimethyl sebacate to sebacic acid:
CH3OOC(CH2)8COOCH3+2H2O→HOOC(CH2)8COOH+2CH3OH
the dimethyl sebacate reaction liquid prepared by the existing electrochemical method is added with water, and rectified to remove methanol and methyl pentaenoate to obtain a crude dimethyl sebacate product, but the inventor finds that 0.5-3% of raw material monomethyl adipate and 2-6% of heavy components can be remained in the crude dimethyl sebacate product, and the monomethyl adipate and the dimethyl sebacate are subjected to azeotropic distillation in the rectification process, so that the purity of the product dimethyl sebacate is not high, the acid value is more than 2mgKOH/g, the requirements of downstream manufacturers can not be met (less than 0.08mgKOH/g), meanwhile, the traditional reduced pressure rectification is adopted, the heavy component residue is easy to polymerize in the concentration increasing process and is easy to adhere to the pipe wall to cause blockage, so that the residual part of dimethyl sebacate in the rectification process is required to dilute the residue concentration to slow down the polymerization, and the heavy component stays in the high-temperature tower kettle for a long time, the polymerization and solidification of heavy components can be accelerated, so that a large amount of dimethyl sebacate enters a kettle residue, the overall yield of the vacuum distillation is low, and no effective means for solving the problem exists at present.
CN 103319340B provides a method for separating and continuously rectifying dimethyl sebacate. Pumping a crude product of dimethyl sebacate into a light component removal tower, heating, and refluxing and distilling to obtain a light component; and feeding the crude ester in the light component removal tower into a heavy component removal tower to reflux and collect the product, discharging the heavy component from the bottom of a reboiler, and cooling the reflux and collected product to obtain the finished product of the dimethyl sebacate. The crude product of the dimethyl sebacate is generated by esterifying sebacic acid and methanol under the action of a catalyst, and does not contain monomethyl adipate azeotropic with the dimethyl sebacate and heavy components with higher viscosity, so the separation technology is not suitable for an electrochemical method for synthesizing the dimethyl sebacate by using the monomethyl adipate as a raw material.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a purification method for electrochemically synthesizing dimethyl sebacate, which can obviously reduce the acid value of a product, avoid polymerization of heavy components in a tower kettle and improve the yield and purity of the dimethyl sebacate product.
In order to achieve the technical effects, the invention adopts the following technical scheme:
the invention provides a purification method for electrochemically synthesizing dimethyl sebacate, which is characterized in that 2, 6-di-tert-butyl-1, 4-benzoquinone and magnesium formate are added into a crude product of electrochemically synthesized dimethyl sebacate, and the dimethyl sebacate is obtained by decompression and supergravity rectification to complete separation and purification.
In the method, the electrochemically synthesized crude product of the dimethyl sebacate is obtained by adding water into a dimethyl sebacate reaction solution prepared by the existing electrochemical method and rectifying to remove methanol and methyl valerate and methyl pentenoate;
preferably, the electrochemically synthesized crude dimethyl sebacate comprises the following components in percentage by mass: 88 to 93 weight percent of dimethyl sebacate, 0.5 to 3 weight percent of monomethyl adipate, 0.5 to 3 weight percent of dimethyl tetradecanedioate, and the balance of heavy components; wherein the heavy component is present in an amount of about 4.5 to 7 wt% and comprises predominantly C14H24O7 1-4wt％、C18H32O6 0.5-2wt％、C40H70O8 1-3wt％；
More preferably, the electrochemically synthesized crude dimethyl sebacate comprises the following components in percentage by mass: 90-92 wt% of dimethyl sebacate, 1.5-2 wt% of monomethyl adipate and 1-1.5 wt% of dimethyl tetradecanedioate;
preferably, the electrochemically synthesized dimethyl sebacate reaction solution is prepared by electrolyzing monomethyl adipate by using an anode electrode, and the anode preferably adopts platinum, platinum titanium and Ti-based PbO2、PtO2、IrO2、RuO2Or tin antimony oxide.
In the method, the adding amount of the 2, 6-di-tert-butyl-1, 4-benzoquinone is 0.5-2 per mill, preferably 1-1.5 per mill of the mass of the crude dimethyl sebacate.
In the method, the adding amount of the magnesium formate is 1-5 percent, preferably 2-4 percent of the mass of the crude dimethyl sebacate.
In the method, the decompression hypergravity rectification is carried out, the vacuum degree (absolute pressure) is 0.5-20KPa, preferably 5-10 KPa; the rotation speed is 1000-; the heating temperature of the tower kettle is 255 ℃ plus 220 ℃, and preferably 240 ℃ plus 230 ℃; the reflux ratio is 5: 1-0.5:1, preferably 2: 1-1:1.
In the method, the decompression hypergravity rectification is completed by a hypergravity rectification machine, and the hypergravity rectification machine is selected from BZ650 and BZ850 of chemical equipment Limited in Chuangjiang, Shanghai dynasty, BZ650 of environmental protection engineering Limited in Shanghai dynasty, BZ650 and BZ750 of chemical equipment Limited in Hangzhou science, and preferably is BZ650-3P of chemical equipment Limited in Hangzhou science.
Preferably, the internal rotor packing of the supergravity rectifying machine is an integral type regular packing selected from any one or a combination of at least two of foam silicon carbide corrugated regular packing, foam nickel regular packing, titanium alloy regular packing, fin guide plate regular packing and modified plastic regular packing; preferably a foamed silicon carbide corrugated structured packing and/or a titanium alloy structured packing.
Preferably, the internal diameter of the integrated packing of the supergravity rectifying machine is 10-300mm, the external diameter is 650-850mm, and the height is 100-500 mm.
In the method, the decompression hypergravity rectification starts to time from the appearance of the first drop of liquid at the top of the hypergravity rectification machine, and the light components at the top of the rectification tower collected within 3-5h are collected to obtain the purified dimethyl sebacate;
preferably, the light component extraction temperature is 155-170 ℃, namely the collection is started when the first drop of liquid appears at the top of the tower at the temperature of about 155 ℃, the collection is stopped when the temperature rises to 170 ℃, and the collection time is about 3-5h, preferably 4.1-4.6 h;
preferably, the mass of the purified dimethyl sebacate extracted from the top of the supergravity rectifying tower is more than 87%, preferably more than 90%, and more preferably more than 92% of the mass of the raw dimethyl sebacate feed;
in the method, the light component extracted from the top of the supergravity rectifying machine is purified dimethyl sebacate, the purity reaches more than 99.5 percent, and the recovery rate of the dimethyl sebacate is more than 98 percent; the acid value of the purified dimethyl sebacate is lower than 0.05mgKOH/g, preferably 0.02-0.04 mgKOH/g;
the heavy component composition extracted from the tower bottom of the supergravity rectifying machine comprises: dimethyl sebacate, magnesium formate, monomethyl adipate, 2, 6-di-tert-butyl-1, 4-benzoquinone and heavy components; wherein the dimethyl sebacate accounts for less than 14 percent, and other components comprise 8 to 36 percent of magnesium formate, 4 to 18 percent of monomethyl adipate, 0.4 to 1.3 percent of 2, 6-di-tert-butyl-1, 4-benzoquinone and about 38 to 51 percent of heavy component (mainly comprising C)14H24O7、C18H32O6、C40H70O8) (ii) a The polymerization conversion of the heavies was less than 5%.
In the prior art, adipic acid is used as a starting material, and in a dimethyl sebacate crude product synthesized by an electrochemical method, due to the fact that the adipic acid contains monomethyl adipate, heavy components and the like, the rectification has the problem of azeotropy with dimethyl sebacate, high purity and dimethyl sebacate are difficult to obtain, and the problem of pipeline blockage is caused by the polymerization of the heavy components at high temperature. The invention adopts the hypergravity rectification technology to purify the crude dimethyl sebacate, strengthens interphase mass transfer by using centrifugal force, can increase the content of light components in gas-phase products, and achieves more excellent separation effect. The addition of magnesium formate can increase the relative volatility between monomethyl adipate and dimethyl sebacate by salt effect, so that adipic acid isThe constant boiling points of monomethyl ester and dimethyl sebacate move upward. In addition, the added magnesium formate and 2, 6-di-tert-butyl-1, 4-benzoquinone can inhibit C in the tower kettle14H24O7，C18H32O6，C40H70O8The equal weight components are polymerized at high temperature, wherein the magnesium formate can be added to have esterification reaction with hydroxyl functional groups in the weight components, so that the magnesium formate is prevented from being polymerized with other molecular carboxyl groups of the weight components, the 2, 6-di-tert-butyl-1, 4-benzoquinone can inhibit the polymerization reaction initiated by unsaturated bonds in the weight components, and the problem of pipeline blockage caused by polymerization of the weight components is effectively avoided under the combined action of the magnesium formate and the 2, 6-di-tert-butyl-1, 4-benzoquinone.
According to the invention, magnesium formate and 2, 6-di-tert-butyl-1, 4-benzoquinone are simultaneously introduced into a rectification system for electrochemically synthesizing dimethyl sebacate, the separation effect is improved and the polymerization of heavy components is inhibited through the synergistic effect of the magnesium formate and the 2, 6-di-tert-butyl-1, 4-benzoquinone, the reduced pressure hypergravity rectification is adopted, the interphase mass transfer is enhanced by using the centrifugal force, the residue of dimethyl sebacate in monomethyl adipate is reduced, the product purity is improved, the retention time of materials in a tower kettle is reduced, and the possibility that the heavy components in the tower kettle are polymerized to block a pipeline is further reduced. The purity of the purified dimethyl sebacate can reach more than 99.5 percent, and the yield can reach more than 98 percent.
Detailed Description
The present invention is further illustrated by the following examples, which should be construed as limiting the scope of the invention.
The main raw materials and equipment information used in the embodiment of the invention are as follows:
crude dimethyl sebacate 1: electrolyzing monomethyl adipate with platinum electrode as anode to obtain reaction solution, adding water, rectifying to remove methanol and methyl penta (enoate), and making into (dimethyl sebacate 93 wt%), monomethyl adipate 0.5 wt%, dimethyl tetradecanedioate 0.5 wt%, and heavy component 6 wt% (mainly including C)14H24O73wt％、C18H32O61.5wt％、C40H70O81.5wt％)；
Crude dimethyl sebacate 2: electrolyzing monomethyl adipate by using a platinum-titanium electrode as an anode to obtain a reaction solution, adding water, and rectifying to remove methanol and methyl penta (enoate) to obtain the catalyst, wherein the catalyst comprises 92 wt% of dimethyl sebacate, 1 wt% of monomethyl adipate, 1.5 wt% of dimethyl tetradecanedioate and 5.5 wt% of heavy components (mainly comprising C)14H24O72wt％、C18H32O60.5wt％、C40H70O83wt％)；
Crude dimethyl sebacate 3: from Ti-based PbO2The electrode is used as an anode to electrolyze monomethyl adipate to obtain reaction liquid, and the reaction liquid is prepared by adding water, rectifying to remove methanol and methyl penta (enoate) and comprises 88 wt% of dimethyl sebacate, 3 wt% of monomethyl adipate, 2 wt% of dimethyl tetradecanedioate and 7 wt% of heavy components (wherein the heavy components mainly comprise C)14H24O74wt％、C18H32O62wt％、C40H70O81wt％)；
Crude dimethyl sebacate 4: from Ti-based PtO2The electrode is used as an anode to electrolyze monomethyl adipate to obtain reaction liquid, and the reaction liquid is prepared by adding water, rectifying to remove methanol and methyl penta (enoate) and comprises 90 wt% of dimethyl sebacate, 2 wt% of monomethyl adipate, 1 wt% of dimethyl tetradecanedioate and 7 wt% of heavy components (wherein the heavy components mainly comprise C)14H24O74wt％、C18H32O61.5wt％、C40H70O81.5wt％)；
Crude dimethyl sebacate 5: IrO from Ti group2The electrode is used as an anode to electrolyze monomethyl adipate to obtain reaction liquid, and the reaction liquid is prepared by adding water, rectifying to remove methanol and methyl penta (enoate), and the components of the reaction liquid comprise 91 wt% of dimethyl sebacate, 1.5 wt% of monomethyl adipate, 3 wt% of dimethyl tetradecanedioate and 4.5 wt% of heavy components (mainly comprising C)14H24O71wt％、C18H32O61.5wt％、C40H70O82wt％)；
Unless otherwise specified, all others are common raw materials purchased from the market.
A hypergravity rectifying machine: stage number is 3, rotor diameter is 650mm, inner cavity height of the rectifier is 900mm, and Hangzhou Keli chemical engineering equipment Limited company BZ 650-3P;
foam silicon carbide corrugated structured packing: 150mm in inner diameter, 650mm in outer diameter, 200mm in height, SUS316L, Hangzhou Keli chemical engineering equipment Co., Ltd;
fin guide plate structured packing: 150mm in inner diameter, 650mm in outer diameter, 200mm in height, SUS316L, Hangzhou Keli chemical engineering equipment Co., Ltd;
foam nickel regular packing: 150mm in inner diameter, 650mm in outer diameter, 200mm in height, SUS316L, Hangzhou Keli chemical engineering equipment Co., Ltd;
the titanium alloy structured packing has the inner diameter of 100mm, the outer diameter of 850mm and the height of 300mm, and the height is 850 x 300 of chemical and mechanical equipment Limited of Jiangxingxing chemical and mechanical engineering company;
the modified plastic structured packing has an inner diameter of 300mm, an outer diameter of 650mm and a height of 500mm, and is 650 x 500 from Shanghaihuang environmental protection engineering Co.
The detection method used in the examples is described below:
the conversion rate and selectivity are determined by using gas chromatography area correction normalized analysis, and the chromatographic analysis conditions are as follows:
the instrument model is as follows: shimadzu GC 2010; a chromatographic column: DB-5 (30X 0.32X 0.25); column temperature: temperature programming (keeping the temperature at 50 ℃ for 4min, then increasing the temperature to 100 ℃ at the temperature increasing rate of 5 ℃/min, then increasing the temperature to 300 ℃ at the temperature increasing rate of 25 ℃/min, and keeping the temperature for 5 min); sample inlet temperature: 230 ℃; FID temperature: 300 ℃; n is a radical of2Flow rate: 1 mL/min; h2Flow rate: 40 mL/min; shock insulator purging (N)2) Flow rate: 3 mL/min; carrier gas (N)2) Flow rate: 1 mL/min; split-flow sample introduction, split-flow ratio: 50; sample introduction amount: 0.1. mu.L.
Example 1
The internal rotor packing of the hypergravity rectifying machine is foam silicon carbide corrugated regular packing, the inner diameter of the packing is 150mm, the outer diameter of the packing is 650mm, and the height of the packing is 200 mm.
The crude product of the dimethyl sebacate to be purified is 1 mass percentComprises the following steps: 93 wt% of dimethyl sebacate, 0.5 wt% of monomethyl adipate, 0.5 wt% of dimethyl tetradecanedioate and 6 wt% of heavy components (mainly comprising C)14H24O73wt％、C18H32O61.5wt％、C40H70O81.5wt％)。
A purification method for electrochemically synthesizing dimethyl sebacate comprises the following steps:
taking 300Kg of crude dimethyl sebacate, adding 0.15Kg of 2, 6-di-tert-butyl-1, 4-benzoquinone and 15Kg of magnesium formate, uniformly mixing, wherein the mass of the 2, 6-di-tert-butyl-1, 4-benzoquinone accounts for 0.5 per mill of the crude raw material, the mass of the magnesium formate accounts for 5 percent of the crude raw material, and transferring the mixture to a supergravity rectifying machine for vacuum rectification. Setting the vacuum degree (absolute pressure) of the rectification process to be 0.5KPa, starting the hypergravity rectification machine, gradually adjusting the rotating speed to be 1000rpm, and heating the oil in the tower kettle to 230 ℃.
When the first drop of liquid appears on the top of the supergravity rectifying machine, light components begin to be collected, the temperature of the top of the tower is 155 ℃ at the moment, the reflux ratio is 5:1, after the light components are collected for 5 hours, the temperature of the top of the tower rises to 170 ℃ at the moment, the collection is stopped, 276Kg of light components are collected from the top of the tower, the light components are 92 percent of the mass of the raw dimethyl sebacate, and the rest of the materials are heavy components collected from the bottom of the tower.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 99.8 percent, and the purification yield is 98.7 percent; the acid value was 0.05 mgKOH/g.
The heavy component extracted from the bottom of the tower is about 39.15kg and comprises the following components: 9.07% of dimethyl sebacate and about 45.98% of heavy components (mainly including C)14H24O723％、C18H32O611.5％、C40H70O811.5 percent) and other components of magnesium formate, monomethyl adipate and 2, 6-di-tert-butyl-1, 4-benzoquinone. The tower kettle has no solidified material, and the polymerization conversion rate of heavy components is 2 percent.
Example 2
The internal rotor packing of the supergravity rectifying machine is foam nickel regular packing, the inner diameter of the packing is 150mm, the outer diameter of the packing is 650mm, and the height of the packing is 200 mm.
Sebacic acid to be purifiedThe dimethyl ester crude product 2 comprises the following components in percentage by mass: 92 wt% of dimethyl sebacate, 1 wt% of monomethyl adipate, 1.5 wt% of dimethyl tetradecanedioate and 5.5 wt% of heavy components (mainly comprising C)14H24O72wt％、C18H32O60.5wt％、C40H70O83wt％)。
A purification method for electrochemically synthesizing dimethyl sebacate comprises the following steps:
taking 300kg of a crude dimethyl sebacate product, adding 0.3kg of 2, 6-di-tert-butyl-1, 4-benzoquinone and 12kg of magnesium formate, uniformly mixing, wherein the mass of the 2, 6-di-tert-butyl-1, 4-benzoquinone accounts for 1 per mill of the crude product raw material, the mass of the magnesium formate accounts for 4 percent of the crude product raw material, and transferring the crude product raw material to a supergravity rectifying machine for vacuum rectification. Setting the vacuum degree (absolute pressure) in the rectification process to be 5KPa, starting the hypergravity rectification machine, gradually adjusting the rotating speed to 2000rpm, and heating the oil in the tower kettle to 240 ℃.
When the first drop of liquid appears on the top of the supergravity rectifying machine, light components begin to be collected, the temperature of the top of the tower is 155 ℃ at the moment, the reflux ratio is 2:1, after the light components are collected for 4.7 hours, the temperature of the top of the tower rises to 170 ℃, the collection is stopped, 272Kg of light components are collected from the top of the tower, the light components are 91 percent of the feeding mass of the crude dimethyl sebacate, and the rest of the materials are heavy components collected from the bottom of the tower.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 99.5 percent, and the purification yield is 98.1 percent; the acid value was 0.04 mgKOH/g.
About 40.3Kg of heavy components are extracted from the bottom of the column, and the composition of the heavy components comprises: 13.3% of dimethyl sebacate and 47.2% of heavy component (mainly including C)14H24O7 14.9wt％、C18H32O610wt％、C40H70O822.3 wt.%), and the other components are magnesium formate, monomethyl adipate, and 2, 6-di-tert-butyl-1, 4-benzoquinone. The tower bottom has no solidified material, and the polymerization conversion rate of heavy components is 3.1 percent.
Example 3
The supergravity rectifying machine uses titanium alloy structured packing as rotor packing, the inner diameter of the packing is 100mm, the outer diameter is 850mm, and the height is 300 mm.
The to-be-purified dimethyl sebacate crude product 3 comprises the following components in percentage by mass: 88 wt% of dimethyl sebacate, 3 wt% of monomethyl adipate, 2 wt% of dimethyl tetradecanedioate and 7 wt% of heavy components (mainly comprising C)14H24O74wt％、C18H32O62wt％、C40H70O81wt％)。
A purification method for electrochemically synthesizing dimethyl sebacate comprises the following steps:
taking 300Kg of crude dimethyl sebacate, adding 0.45Kg of 2, 6-di-tert-butyl-1, 4-benzoquinone and 6Kg of magnesium formate, uniformly mixing, wherein the mass of the 2, 6-di-tert-butyl-1, 4-benzoquinone accounts for 1.5 per mill of the crude raw material, the mass of the magnesium formate accounts for 2 per mill of the crude raw material, and transferring the mixture to a supergravity rectifying machine for vacuum rectification. Setting the vacuum degree (absolute pressure) of the rectification process to be 10KPa, starting the hypergravity rectification machine, gradually adjusting the rotating speed to be 3000rpm, and heating the oil in the tower kettle to be 220 ℃.
When the first drop of liquid appears on the top of the supergravity rectifying machine, light components begin to be collected, the temperature of the top of the tower is 155 ℃ at the moment, the reflux ratio is 1:1, after the light components are collected for 4.2 hours, the temperature of the top of the tower rises to 170 ℃ at the moment, the collection is stopped, 261Kg of light components are collected from the top of the tower, the light components are 87 percent of the feeding mass of the crude dimethyl sebacate, and the rest of the materials are heavy components collected from the bottom of the tower.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 99.6 percent, and the purification yield is 98.5 percent; the acid value was 0.02 mgKOH/g.
About 45.45Kg of heavy components extracted from the bottom of the column consists of: 8.9% of dimethyl sebacate and about 46.2% of heavy component (mainly including C)14H24O726.4wt％、C18H32O613.2wt％、C40H70O86.6 wt.%), and other components including magnesium formate, monomethyl adipate, and 2, 6-di-tert-butyl-1, 4-benzoquinone. The tower bottom has no solidified material, and the polymerization conversion rate of heavy components is 5.0 percent.
Example 4
The internal rotor packing of the hypergravity rectifying machine is fin guide plate regular packing, the inner diameter of the packing is 150mm, the outer diameter of the packing is 650mm, and the height of the packing is 200 mm.
The to-be-purified dimethyl sebacate crude product 4 comprises the following components in percentage by mass: 90 wt% of dimethyl sebacate, 2 wt% of monomethyl adipate, 1 wt% of dimethyl tetradecanedioate and 7 wt% of heavy components (mainly comprising C)14H24O74wt％、C18H32O61.5wt％、C40H70O81.5wt％)。
A purification method for electrochemically synthesizing dimethyl sebacate comprises the following steps:
taking 300Kg of crude dimethyl sebacate, adding 0.6Kg of 2, 6-di-tert-butyl-1, 4-benzoquinone and 9Kg of magnesium formate, uniformly mixing, wherein the mass of the 2, 6-di-tert-butyl-1, 4-benzoquinone accounts for 2 per mill of the crude raw material, the mass of the magnesium formate accounts for 3 percent of the crude raw material, and transferring the mixture to a supergravity rectifying machine for vacuum rectification. Setting the vacuum degree (absolute pressure) of the rectification process to be 20KPa, starting the hypergravity rectification machine, gradually adjusting the rotating speed to be 4000rpm, and heating the oil in the tower kettle to be 255 ℃.
When the first drop of liquid appears on the top of the supergravity rectifying machine, light components begin to be collected, the temperature of the top of the tower is 155 ℃ at the moment, the reflux ratio is 0.5:1, after the light components are collected for 3.3 hours, the temperature of the top of the tower rises to 170 ℃, the collection is stopped, 268Kg of light components are collected from the top of the tower, the light components are 89% of the feeding mass of the crude dimethyl sebacate product, and the rest of the materials are heavy components collected from the bottom of the tower.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 99.9 percent, and the purification yield is 99.1 percent; the acid value was 0.03 mgKOH/g.
About 41.6Kg of heavy components are extracted from the bottom of the column, and the composition of the heavy components comprises: dimethyl sebacate in 5.45 wt% and heavy component in 50.6 wt% (mainly including C)14H24O728.8wt％、C18H32O610.8wt％、C40H70O811.0 wt.%), magnesium formate, monomethyl adipate, 2, 6-di-tert-butyl-1, 4-benzoquinone, among others. The tower bottom has no solidified material, and the polymerization conversion rate of heavy components is 3.2 percent.
Example 5
The internal rotor packing of the hypergravity rectifying machine is modified plastic regular packing, the inner diameter of the packing is 300mm, the outer diameter of the packing is 650mm, and the height of the packing is 500 mm.
The to-be-purified dimethyl sebacate crude product 5 comprises the following components in percentage by mass: 91 wt% of dimethyl sebacate, 1.5 wt% of monomethyl adipate, 3 wt% of dimethyl tetradecanedioate and 4.5 wt% of heavy components (mainly comprising C)14H24O71wt％、C18H32O61.5wt％、C40H70O82wt％)。
A purification method for electrochemically synthesizing dimethyl sebacate comprises the following steps:
taking 300Kg of crude dimethyl sebacate, adding 0.45Kg of 2, 6-di-tert-butyl-1, 4-benzoquinone and 3Kg of magnesium formate, uniformly mixing, wherein the mass of the 2, 6-di-tert-butyl-1, 4-benzoquinone accounts for 1.5 per mill of the crude raw material, the mass of the magnesium formate accounts for 1 percent of the crude raw material, and transferring the crude product to a supergravity rectifying machine for vacuum rectification. Setting the vacuum degree (absolute pressure) of the rectification process to be 10KPa, starting the hypergravity rectification machine, gradually adjusting the rotating speed to be 1000rpm, and heating the oil in the tower kettle to be 240 ℃.
When the first drop of liquid appears on the top of the supergravity rectifying machine, light components begin to be collected, the temperature of the top of the tower is 155 ℃ at the moment, the reflux ratio is 1:1, the light components are collected for 250min, the temperature of the top of the tower rises to 170 ℃ at the moment, the collection is stopped, 270Kg of the light components are collected from the top of the tower, the light components are 90 percent of the feeding mass of the crude dimethyl sebacate, and the rest of the materials are heavy components collected from the bottom of the tower.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 99.5 percent, and the purification yield is 98.4 percent; the acid value was 0.04 mgKOH/g.
About 33.45Kg of heavy components are extracted from the bottom of the column and comprise: 13% of dimethyl sebacate and about 40.36% of heavy component (mainly including C)14H24O78.97wt％、C18H32O613.45wt％、C40H70O817.94 wt.%), magnesium formate, monomethyl adipate, 2, 6-di-tert-butyl-1, 4-benzoquinone, among others. The tower bottom has no solidified material, and the polymerization conversion rate of heavy components is 2.4 percent.
Comparative example 1
The purification method of the embodiment 1 is carried out according to the difference that 2, 6-di-tert-butyl-1, 4-benzoquinone is not added, the crude product of the pure dimethyl sebacate is directly fed into a hypergravity rectifying machine for rectification, and other operations and parameters are the same as those of the embodiment 1.
248Kg of light components are extracted from the tower top, which is 83 percent of the feeding mass of the crude dimethyl sebacate product.
The light component extracted from the tower top is purified dimethyl sebacate with the purity of 81.5 percent and the purification yield of 72 percent; the acid value was 2.5 mgKOH/g.
12.6Kg of solid material was collected at the bottom of the column, and the polymerization conversion rate of the heavy component was 70.2%.
Comparative example 2
The purification process of example 1 was followed, except that 2, 6-di-tert-butyl-1, 4-benzoquinone was replaced with p-benzoquinone of equal mass, which was then rectified in a super gravity rectifier, and the other operations and parameters were the same as in example 1.
236Kg of light components are extracted from the top of the tower and are 78.7 percent of the mass of the raw feed of the dimethyl sebacate.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 91.8 percent, and the purification yield is 78 percent; the acid value was 3.2 mgKOH/g.
15.5Kg of solid material was collected at the bottom of the column, and the polymerization conversion of the heavy component was 86%.
Comparative example 3
The purification method of example 1 was followed, except that magnesium formate was not added, and the crude dimethyl sebacate was directly rectified in a super-gravity rectifier, and the other operations and parameters were the same as in example 1.
231Kg of light components are extracted from the top of the tower and are 77 percent of the mass of the raw feed of the dimethyl sebacate.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 90.1%, and the purification yield is 73%; the acid value was 2.8 mgKOH/g.
7.65Kg of solid material was collected at the bottom of the column, and the polymerization conversion of the heavy component was 42.5%.
Comparative example 4
The purification process of example 1 was followed, except that magnesium formate was replaced with equal mass of sodium formate, which was then rectified in a super gravity rectifier, and the other operations and parameters were the same as in example 1.
225Kg of light components are extracted from the top of the tower and are 75 percent of the mass of the raw feed of the dimethyl sebacate.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 89.4%, and the purification yield is 72%; the acid value was 1.66 mgKOH/g.
4.82Kg of solid material was collected at the bottom of the column, and the polymerization conversion of the heavy component was 26.8%.
Comparative example 5
The purification process of example 1 was followed, except that the supergravity rectifier was used in accordance with a conventional rectification column without opening the centrifuge, and other operations and parameters were the same as those of example 1.
235Kg of light components are extracted from the tower top, which is 78 percent of the feeding mass of the crude dimethyl sebacate product.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 92.1 percent, and the purification yield is 78 percent; the acid value was 3.7 mgKOH/g.
10.66Kg of solid material was collected at the bottom of the column, and the polymerization conversion of the heavy component was 59.2%.
Comparative example 6
The method adopts a dimethyl sebacate conventional rectification mode (common rectification without adding 2, 6-di-tert-butyl-1, 4-benzoquinone and magnesium formate), and comprises the following steps:
the common rectifying tower is filled with regular titanium alloy packing with the diameter of 100mm and the height of 2000 mm.
The crude dimethyl sebacate to be purified is the same as in example 1.
300Kg of crude dimethyl sebacate is taken to a common rectifying tower for vacuum rectification operation. The vacuum degree (absolute pressure) in the rectification process is set to be 0.5KPa, and the temperature of the heating oil in the tower kettle is set to be 220 ℃.
Collecting light components when the first drop of liquid appears at the top of the supergravity rectifying machine, timing the temperature at the top of the tower at 160 ℃ and the reflux ratio at 10:1, collecting for 400min, stopping collecting when the temperature at the top of the tower rises to 170 ℃,
195Kg of light components are extracted from the tower top and are 65 percent of the mass of the raw feed of the dimethyl sebacate.
The light component extracted from the tower top is purified dimethyl sebacate, the purity is 87.6 percent, and the purification yield is 61 percent; the acid value was 2.6 mgKOH/g.
16.97Kg of solid material is collected at the bottom of the tower, and the polymerization conversion rate of heavy components is 94.3%.

Claims (10)

1. The method is characterized in that 2, 6-di-tert-butyl-1, 4-benzoquinone and magnesium formate are added into a crude product of electrochemically synthesized dimethyl sebacate, and the dimethyl sebacate is obtained through reduced pressure and supergravity rectification to complete separation and purification.
2. The purification method of claim 1, wherein the electrochemically synthesized crude dimethyl sebacate is obtained by adding water to a reaction solution of dimethyl sebacate prepared by an electrochemical method, and rectifying to remove methanol and methyl valerate and methyl pentenoate;
preferably, the electrochemically synthesized crude dimethyl sebacate comprises the following components in percentage by mass: 88 to 93 weight percent of dimethyl sebacate, 0.5 to 3 weight percent of monomethyl adipate, 0.5 to 3 weight percent of dimethyl tetradecanedioate, and the balance of heavy components; wherein the weight fraction of the heavy components is about 4.5 to 7 wt%, including C14H24O7 1-4wt％、C18H32O6 0.5-2wt％、C40H70O8 1-3wt％；
More preferably, the electrochemically synthesized crude dimethyl sebacate comprises the following components in percentage by mass: 90-92 wt% of dimethyl sebacate, 1.5-2 wt% of monomethyl adipate and 1-1.5 wt% of dimethyl tetradecanedioate.
3. Purification process according to claim 1 or 2, characterized in that the 2, 6-di-tert-butyl-1, 4-benzoquinone is added in an amount of 0.5 to 2%, preferably 1 to 1.5%, by mass of the crude dimethyl sebacate.
4. Purification process according to any one of claims 1 to 3, characterized in that the magnesium formate is added in an amount of 1 to 5%, preferably 2 to 4%, by mass of the crude dimethyl sebacate.
5. Purification process according to any one of claims 1 to 4, characterized in that the rectification under reduced pressure is carried out by hypergravity with a vacuum of 0.5 to 20KPa, preferably of 5 to 10 KPa; the rotation speed is 1000-; the heating temperature of the tower kettle is 255 ℃ plus 220 ℃, and preferably 240 ℃ plus 230 ℃; the reflux ratio is 5: 1-0.5:1, preferably 2: 1-1:1.
6. The purification method according to any one of claims 1 to 5, wherein the reduced pressure super gravity rectification is performed by a super gravity rectification machine selected from BZ650 and BZ850 of Chujiang creative chemical industry, Inc., BZ650 and BZ750 of Shanghai Dynasty environmental protection engineering, Inc., and BZ650-3P of Hangzhou Keli chemical industry, Inc.
7. The purification method according to any one of claims 1 to 6, wherein the internal rotor packing of the hypergravity rectifying machine is monolithic structured packing selected from any one of or a combination of at least two of foamed silicon carbide corrugated structured packing, foamed nickel structured packing, titanium alloy structured packing, fin guide plate structured packing, modified plastic structured packing; preferably a foamed silicon carbide corrugated structured packing and/or a titanium alloy structured packing.
8. The purification method as claimed in any one of claims 1 to 7, wherein the internal diameter of the integrated packing of the super gravity rectifier is 10-300mm, the external diameter is 650-850mm, and the height is 100-500 mm.
9. The purification method according to any one of claims 1 to 8, wherein the decompression hypergravity rectification is performed, and the light components at the top of the tower which are extracted within 3 to 5 hours are collected from the beginning of the appearance of the first drop of liquid at the top of the hypergravity rectification machine, so as to obtain the purified dimethyl sebacate.
10. Purification method according to any one of claims 1 to 9, characterized in that the light fraction is withdrawn at a temperature of 155 ℃ and 170 ℃ for a time of 3 to 5h, preferably 4.1 to 4.6 h.
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