CN1594313A - Process for continuous preparation of lactide - Google Patents
Process for continuous preparation of lactide Download PDFInfo
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- CN1594313A CN1594313A CN 200410013457 CN200410013457A CN1594313A CN 1594313 A CN1594313 A CN 1594313A CN 200410013457 CN200410013457 CN 200410013457 CN 200410013457 A CN200410013457 A CN 200410013457A CN 1594313 A CN1594313 A CN 1594313A
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Abstract
The invention relates to a process for continuous preparation of lactide which consists of, charging raw material lactic acid into container A, the low polymerization lactic acid obtained in container A entering container B under the action of pressure difference, pyrolytic cracking the low polymerization lactic acid, obtaining lactide crude product through vacuum distillation, disintegrating and purifying the crude product to obtain the lactide.
Description
Technical field
The present invention relates to the preparation method of rac-Lactide, belong to the organic synthesis field.
Background technology
The structure of rac-Lactide is as follows:
In the present invention's explanation,, only in narration, replace with words such as left-handed, dextrorotation, racemize and mesos with in the chemical structure examination of rac-Lactide, not showing its steric configuration.
Rac-Lactide is a monomer of making the degradable polyester poly(lactic acid), generally is that the thermal degradation from lact-acid oligomer obtains.The classical synthetic method of rac-Lactide, as described in United States Patent (USP) (US Pat.6277951B1): lactic acid is placed polycondensation obtains low-molecular-weight poly(lactic acid) under the effect of certain process conditions and catalyzer, low-molecular-weight poly(lactic acid) thermo-cracking can be obtained rac-Lactide.
It should be noted that " continuously " described in the present disclosed in the world document make the method (USPat.6277951B1, US Pat.6326458B1) of rac-Lactide and remain the manufacture method at intermittence in fact; That is to say, steps A and step B are separate in above-mentioned reaction, steps A is only supplied raw materials for step B, and steps A or step B self also be a rhythmic reaction process, can not realize that the serialization of two reactions is carried out and the continuous flow of material between two flow processs.
There is serious problem in this traditional intermittent reaction method, promptly preparing in the process of rac-Lactide in cracking causes material to conduct heat slowly because of reactant viscosity constantly increases easily, system is heated inhomogeneous, local temperature is too high, and the result causes side reactions such as material charing, the decline of rac-Lactide productive rate, optical activity rac-Lactide generation racemization; If heat for a long time also decomposition reaction might take place, generate materials such as undesirable carbon monoxide, vinylformic acid and aldehyde.
A kind of way that overcomes this situation is to adopt some inert solvents, and therefore for example high boiling alkane, but poisonous, the inflammable often compound of these high boiling solvents make the manufacturing of rac-Lactide become dangerous.
Summary of the invention
Problem to be solved by this invention provides a kind of method of continuous manufacturing rac-Lactide, and this method adopts continuous reaction, and is safe and reliable, the productive rate height.
The contriver finds under same temperature condition, low this fact of the viscosity of long-time heating afterreaction material in the viscosity ratio thermal cracking processes of lact-acid oligomer, consider to reduce the viscosity of reaction mass by the method that adds lact-acid oligomer, conduct heat and mass transfer process thereby improve, reduce the generation of side reaction, improve speed and yield that rac-Lactide is made.
Technical scheme provided by the invention is: a kind of method of continuous manufacturing rac-Lactide, with container A and container B by the conduit connection is reaction vessel, in the mode of continuous adding reaction mass material acid being joined temperature of reaction is 50～150 ℃, in the container A of pressure 0.001MPa～0.1MPa, the polymerization degree that generates in container A is that to enter temperature of reaction under the effect of pressure difference be 160～250 ℃ for 2～30 lact-acid oligomer, in the container B of pressure 1Pa～0.001MPa, enter the lact-acid oligomer generation thermo-cracking of container B, the rac-Lactide crude product that underpressure distillation goes out to generate, crude product obtains rac-Lactide through separation and purification; Steam in the process at rac-Lactide, in container A, add material acid continuously by the elution speed of rac-Lactide.
The present invention makes lactic acid (as L-lactic acid by the mode of continuous adding reaction mass, D-lactic acid or D, L-lactic acid) reaction generates lact-acid oligomer incessantly, then at high temperature the mode by continuous adding reaction mass make lact-acid oligomer incessantly thermo-cracking generate rac-Lactide.Promptly can be used for polyreaction after rac-Lactide is purified.The entire reaction course that the present invention makes rac-Lactide from lactic acid is continual.This method is safe and reliable, the productive rate height.
Continuous manufacturing of the present invention is meant that lactic acid polycondensation and these two reaction process of lact-acid oligomer cracking are non-stop, rather than refers to that the front and back between the technical process are connected in proper order; In other words, on one side promptly can add reaction mass in the reaction process, Yi Bian generate product and enter next flow process, material can continuous flow between two flow processs; The lactic raw material that adopts is any one in D-lactic acid, dextrolactic acid or the racemic lactic acid; The final rac-Lactide of making can be levorotatory lactide, dextrorotation rac-Lactide, rac-lactide or Study of Meso-Lactide; Lactic acid polycondensation and lact-acid oligomer cracking are all carried out under heating condition; Lactic acid polycondensation and lact-acid oligomer cracking are all carried out under the vacuum decompression condition; Catalyzer can be used in lactic acid polycondensation or the lact-acid oligomer cracking process, also catalyzer can be do not used; Catalyst consumption is the 0.01%-10% of material acid quality; The catalyzer that uses comprises zinc powder, zinc oxide, zinc lactate, glass putty, tin protoxide, stannous octoate etc.; The rac-Lactide crude product that the lactic acid cracking obtains needs further separation and purification; Separation and purification can be filtration, washing, distillation or recrystallization; The by product that obtains after the further separation and purification of the rac-Lactide that the lactic acid cracking obtains can be used as raw material and enters lactic acid polycondensation reaction; The by product of separation and purification can be the undesirable cut that obtains in the waste liquid, distillation after the filtrate that obtains after the filtration of crude product, the washing and the mother liquor of recrystallization.
Description of drawings
Accompanying drawing is the structural representation of the used reaction vessel of the present invention.Wherein: 1 is opening for feed; 2,7 is vacuum orifice; 3,6 be respectively steam outlet, rac-Lactide discharge port; 4 is the conduit together with reaction vessel A and B; 5 are the piston of control from the A container to B container feeding rate; The A container is a lactic acid polycondensation reaction device, and the B container is made the rac-Lactide device for the lact-acid oligomer cracking; A is a lactic acid, and b is a rac-Lactide, and c is a by product, and d is a water.
Embodiment
Below be embodiments of the invention, these embodiment should not be counted as limitation of the present invention.
Embodiment 1: referring to accompanying drawing, with conduit 4 connection reaction flask A and another reaction flask B of a band piston 5, reaction flask A is provided with opening for feed 1, vacuum orifice 2 and steam outlet 3, and reaction flask B is provided with discharge port 6 and vacuum orifice 7.In advance 500 grams, 85% racemic lactic acid and 5 gram zinc powders are dropped among the reaction flask A, induction stirring, 100 ℃ with 0.001MPa under carry out polycondensation to obtain the polymerization degree be 10 oligomeric racemic lactic acid.Temperature among the reaction flask B is 200 ℃, pressure 100Pa.Oligomeric racemic lactic acid speed with about 5 gram/minute under the effect of the pressure difference of two bottles of A, B enters the B bottle from the A bottle, enter the oligomeric racemic lactic acid generation thermo-cracking of B bottle, the rac-lactide crude product that underpressure distillation goes out to generate, the crude product washing with alcohol is filtered and is obtained white rac-lactide.Steam in the process at rac-lactide, in the A bottle, add racemic lactic acid continuously, keep material balance by the elution speed of rac-lactide.The elution speed of rac-lactide is 4 hours with the control residence time of lactic acid in the A bottle.Dropwise 5 00 gram lactic acid can get rac-Lactide 183 grams, productive rate 47%.
Embodiment 2: device is with embodiment 1.Dextrolactic acid with 600 grams 85% drops among the reaction flask A in advance, induction stirring, carrying out polycondensation under 140 ℃ and 0.01MPa, to obtain the polymerization degree be 15 oligomeric dextrolactic acid, conduit with a band piston is communicated with flask A and another reaction flask B, temperature among the reaction flask B is 180 ℃, pressure 10Pa, oligomeric dextrolactic acid is at A, speed with about 5 gram/minute under the effect of the pressure difference that B is two bottles enters the B bottle from the A bottle, enter the oligomeric dextrolactic acid generation thermo-cracking of B bottle, the dextrorotation rac-Lactide crude product that underpressure distillation goes out to generate, the crude product re-crystallizing in ethyl acetate is filtered and is obtained white dextrorotation rac-Lactide.Steam in the process at the dextrorotation rac-Lactide, in the A bottle, add dextrolactic acid continuously, keep material balance by the elution speed of dextrorotation rac-Lactide.The elution speed of dextrorotation rac-Lactide is 2 hours with the control residence time of lactic acid in the A bottle.Dropwise 5 00 gram lactic acid can get dextrorotation rac-Lactide 285 grams, productive rate 70%.
Embodiment 3: device is with embodiment 1.In advance in the D-lactic acid and 3 gram zinc oxide reaction flask A with 550 grams 85%, induction stirring, carrying out polycondensation under 140 ℃ and 0.01MPa, to obtain the polymerization degree be 18 low PLLA, conduit with a band piston is communicated with flask A and another reaction flask B, temperature among the reaction flask B is 180 ℃, pressure 10Pa, low PLLA is at A, speed with about 5 gram/minute under the effect of the pressure difference that B is two bottles enters the B bottle from the A bottle, enter the low PLLA generation thermo-cracking of B bottle, the levorotatory lactide crude product that underpressure distillation goes out to generate, the crude product re-crystallizing in ethyl acetate is filtered and is obtained white levorotatory lactide.Steam in the process at levorotatory lactide, in the A bottle, add D-lactic acid continuously, keep material balance by the elution speed of levorotatory lactide.The elution speed of levorotatory lactide is 2 hours with the control residence time of lactic acid in the A bottle.Dropwise 5 00 gram lactic acid can get levorotatory lactide 221 grams, productive rate 87%.
Embodiment 4: device is with embodiment 1.5 gram zinc lactates are dropped among the reaction flask A, induction stirring under 100 ℃ and 0.001MPa vacuum decompression, get 600 grams, 85% racemic lactic acid and splash into a bottle A with the speed of 5 gram/minute, the conduit that the polymerization degree that obtains is 16 oligomeric racemic lactic acid by above-mentioned band piston is at A, speed with about 3 gram/minute under the effect of the pressure difference that B is two bottles enters the B bottle from the A bottle, temperature among the reaction flask B is 200 ℃, pressure 5Pa, enter the oligomeric racemic lactic acid generation thermo-cracking of B bottle, the rac-lactide crude product that underpressure distillation goes out to generate, the crude product washing with alcohol, filtration obtains white rac-lactide 196 grams, productive rate 48%.
Embodiment 5: device is with embodiment 1.5 gram glass puttys are dropped among the reaction flask A, induction stirring under 150 ℃ and 0.001MPa vacuum decompression, get 1200 grams, 85% D-lactic acid and splash into a bottle A with the speed of 5 gram/minute, the conduit that the polymerization degree that obtains is 25 low PLLA by above-mentioned band piston is at A, speed with about 3 gram/minute under the effect of the pressure difference that B is two bottles enters the B reaction flask from the A bottle, temperature among the reaction flask B is 190 ℃, pressure 10Pa, enter the low PLLA generation thermo-cracking of B bottle, the levorotatory lactide crude product that underpressure distillation goes out to generate, the crude product washing with alcohol, filtration obtains white levorotatory lactide 785 grams, productive rate 82%.
Embodiment 6: device is with embodiment 1.5 gram tin protoxides are dropped among the reaction flask A, induction stirring under 100 ℃ and 0.01MPa vacuum decompression, get the mother liquor that produces in the 500 gram rac-lactide recrystallization processes, splash into a bottle A by a dropping funnel that is connected on bottle A with the speed of 5 gram/minute, the conduit of the oligomeric racemic lactic acid that obtains by above-mentioned band piston with oligomeric racemic lactic acid at A, speed with about 4 gram/minute under the effect of the pressure difference that B is two bottles enters the B reaction flask from the A bottle, temperature among the reaction flask B is 200 ℃, pressure 5Pa, enter the oligomeric racemic lactic acid generation thermo-cracking of B bottle, the rac-lactide crude product that underpressure distillation goes out to generate, the crude product washing with alcohol, filtration obtains white rac-lactide 220 grams, productive rate 44%.
Embodiment 7: device is with embodiment 1.Be 30 low PLLA in advance with the 200 gram polymerization degree with 3 gram stannous octoates input reaction flask A in, induction stirring, 140 ℃ of temperature, vacuum tightness 0.01MPa, conduit with a band piston is communicated with reaction flask A and another reaction flask B, temperature among the reaction flask B is 180 ℃, pressure 10Pa, lact-acid oligomer enters the B bottle from the A bottle under the effect of the pressure difference of two bottles of A, B, enter the low PLLA generation thermo-cracking of B bottle, the levorotatory lactide crude product that underpressure distillation goes out to generate, the crude product re-crystallizing in ethyl acetate is filtered and is obtained white levorotatory lactide.Steam in the process at levorotatory lactide, in the A bottle, add D-lactic acid continuously, keep material balance by the elution speed of levorotatory lactide.The elution speed of levorotatory lactide is 2 hours with the control residence time of lactic acid in the A bottle.Add 500 gram lactic acid and can get rac-Lactide 221 grams, productive rate 87%.
Claims (7)
1. method of making continuously rac-Lactide, it is characterized in that: with container A and container B by the conduit connection is reaction vessel, in the mode of continuous adding reaction mass material acid being joined temperature of reaction is 50～150 ℃, in the container A of pressure 0.001MPa～0.1MPa, the polymerization degree that generates in container A is that to enter temperature of reaction under the effect of pressure difference be 160～250 ℃ for 2～30 lact-acid oligomer, in the container B of pressure 1Pa～0.001MPa, enter the lact-acid oligomer generation thermo-cracking of container B, the rac-Lactide crude product that underpressure distillation goes out to generate, crude product obtains rac-Lactide through separation and purification; Steam in the process at rac-Lactide, in container A, add material acid continuously by the elution speed of rac-Lactide.
2. the method for continuous manufacturing rac-Lactide according to claim 1 is characterized in that: raw materials used lactic acid is D-lactic acid, dextrolactic acid or racemic lactic acid.
3. the method for continuous manufacturing rac-Lactide according to claim 1 and 2 is characterized in that: be added with catalyzer in the lactic acid in the container A.
4. the method for continuous manufacturing rac-Lactide according to claim 3 is characterized in that: catalyzer is zinc powder, zinc oxide, zinc lactate, glass putty, tin protoxide or stannous octoate.
5. the method for continuous manufacturing rac-Lactide according to claim 3 is characterized in that: catalyst consumption is the 0.01%-10% of material acid quality.
6. the method for continuous manufacturing rac-Lactide according to claim 1 and 2 is characterized in that: the elution speed of rac-Lactide is control in 2～4 hours by material acid residence time in container A.
7. the method for continuous manufacturing rac-Lactide according to claim 1 and 2 is characterized in that: separation and purification is filtration, washing, distillation or recrystallization.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410013457 CN1284779C (en) | 2004-07-13 | 2004-07-13 | Process for continuous preparation of lactide |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410013457 CN1284779C (en) | 2004-07-13 | 2004-07-13 | Process for continuous preparation of lactide |
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| CN1594313A true CN1594313A (en) | 2005-03-16 |
| CN1284779C CN1284779C (en) | 2006-11-15 |
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| CN 200410013457 Expired - Fee Related CN1284779C (en) | 2004-07-13 | 2004-07-13 | Process for continuous preparation of lactide |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100444947C (en) * | 2005-06-16 | 2008-12-24 | 中国纺织科学研究院 | Lactide analog monomer continuous polymerization device and process |
| CN102348673A (en) * | 2009-04-14 | 2012-02-08 | 银河股份公司 | Chemical recycling of pla by hydrolysis |
| CN102766132A (en) * | 2012-08-14 | 2012-11-07 | 北京普利玛科技有限责任公司 | Method for preparing lactide continuously |
| CN101747314B (en) * | 2009-12-25 | 2013-02-13 | 南开大学 | Process method for synthesizing L-lactide by molecular sieve catalytic pyrolysis method |
| CN102007159B (en) * | 2008-04-15 | 2013-03-13 | 巴斯夫欧洲公司 | Method for the continuous production of biodegradable polyesters |
| CN105218512A (en) * | 2014-06-09 | 2016-01-06 | 江南大学 | A kind of new preparation process of glycollide |
| CN106146817A (en) * | 2015-04-21 | 2016-11-23 | 上海浦景化工新材料有限公司 | Hydroxy alkanoic acid zinc polyester catalyst, the application of its preparation method and this catalyst |
| CN109160913A (en) * | 2018-04-27 | 2019-01-08 | 北京理工大学 | A kind of method of the rodlike long crystal of L- lactide of synthesizing optical purity is high |
| US10392362B2 (en) | 2016-02-24 | 2019-08-27 | The Hong Kong Research Institute Of Textiles And Apparel Limited | Method for synthesizing lactide by means of catalysis of lactid acid |
| CN111153886A (en) * | 2020-01-16 | 2020-05-15 | 南京大学 | Method and device for synthesizing lactide with high yield and rapidness |
| CN112480064A (en) * | 2020-12-21 | 2021-03-12 | 天津科技大学 | Method for synthesizing lactide through back-pack type continuous rectification |
| CN115073418A (en) * | 2022-07-27 | 2022-09-20 | 中国科学院青岛生物能源与过程研究所 | Magnesium catalyst and method for recovering racemic lactide by depolymerizing high-regularity polylactic acid by using same |
-
2004
- 2004-07-13 CN CN 200410013457 patent/CN1284779C/en not_active Expired - Fee Related
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100444947C (en) * | 2005-06-16 | 2008-12-24 | 中国纺织科学研究院 | Lactide analog monomer continuous polymerization device and process |
| CN102007159B (en) * | 2008-04-15 | 2013-03-13 | 巴斯夫欧洲公司 | Method for the continuous production of biodegradable polyesters |
| CN102348673A (en) * | 2009-04-14 | 2012-02-08 | 银河股份公司 | Chemical recycling of pla by hydrolysis |
| CN102348673B (en) * | 2009-04-14 | 2015-04-15 | 银河股份公司 | Chemical recycling of pla by hydrolysis |
| CN101747314B (en) * | 2009-12-25 | 2013-02-13 | 南开大学 | Process method for synthesizing L-lactide by molecular sieve catalytic pyrolysis method |
| CN102766132A (en) * | 2012-08-14 | 2012-11-07 | 北京普利玛科技有限责任公司 | Method for preparing lactide continuously |
| CN102766132B (en) * | 2012-08-14 | 2015-08-19 | 北京普利玛科技有限责任公司 | A kind of method of continuous production rac-Lactide |
| CN105218512B (en) * | 2014-06-09 | 2018-03-02 | 毛文学 | A kind of preparation technology of glycolide |
| CN105218512A (en) * | 2014-06-09 | 2016-01-06 | 江南大学 | A kind of new preparation process of glycollide |
| CN106146817A (en) * | 2015-04-21 | 2016-11-23 | 上海浦景化工新材料有限公司 | Hydroxy alkanoic acid zinc polyester catalyst, the application of its preparation method and this catalyst |
| CN106146817B (en) * | 2015-04-21 | 2019-04-05 | 上海浦景化工新材料有限公司 | Hydroxy alkanoic acid zinc polyester catalyst, the application of preparation method and the catalyst |
| US10392362B2 (en) | 2016-02-24 | 2019-08-27 | The Hong Kong Research Institute Of Textiles And Apparel Limited | Method for synthesizing lactide by means of catalysis of lactid acid |
| CN109160913A (en) * | 2018-04-27 | 2019-01-08 | 北京理工大学 | A kind of method of the rodlike long crystal of L- lactide of synthesizing optical purity is high |
| CN111153886A (en) * | 2020-01-16 | 2020-05-15 | 南京大学 | Method and device for synthesizing lactide with high yield and rapidness |
| CN112480064A (en) * | 2020-12-21 | 2021-03-12 | 天津科技大学 | Method for synthesizing lactide through back-pack type continuous rectification |
| CN115073418A (en) * | 2022-07-27 | 2022-09-20 | 中国科学院青岛生物能源与过程研究所 | Magnesium catalyst and method for recovering racemic lactide by depolymerizing high-regularity polylactic acid by using same |
| CN115073418B (en) * | 2022-07-27 | 2024-01-26 | 中国科学院青岛生物能源与过程研究所 | Zinc complex catalyst and method for depolymerizing high-regularity polylactic acid and recycling racemic lactide |
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| CN1284779C (en) | 2006-11-15 |
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