CN1488628A - Method for preparing lactide - Google Patents
Method for preparing lactide Download PDFInfo
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- CN1488628A CN1488628A CNA03142029XA CN03142029A CN1488628A CN 1488628 A CN1488628 A CN 1488628A CN A03142029X A CNA03142029X A CN A03142029XA CN 03142029 A CN03142029 A CN 03142029A CN 1488628 A CN1488628 A CN 1488628A
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- lactide
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- lactic acid
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Abstract
The invention refers to a method for producing lactide. The character lies in: under the protection of inert gas, the invention uses instillation to eliminate the water in lactic acid, then uses an azeotropic solvent which can make the condensation reaction advantage to generate lactide, the solvent is good solvent to lactide and the bad solvent to lactic acid polymer, the solvent flows back in the protection of inert gas continuously, make the lactic acid is condensed into lactide, then decompression distillation is carried on, through recrystallization there gets the high purity lactide.
Description
[technical field]
The present invention relates to chemical field, a kind of specifically method for preparing rac-Lactide.
[technical background]
Poly(lactic acid) is a kind of synthetic macromolecular compound of energy complete biodegradable.Because material acid can utilize the agricultural-food fermentation to make, thereby is considered to Sustainable development, eco-friendly compound.And because poly(lactic acid) has excellent biological compatibility, metabolic in vivo intermediate product is the eubolism product lactic acid of sugar, and final meta-bolites is carbonic acid gas and water.Therefore poly(lactic acid) has extensive studies and application prospect as controlled release drug delivery system mechanism material, operating sutures, tissue engineering bracket material and bone renovating material.
Usually, the preparation of poly(lactic acid) has two lines, i.e. direct polycondensation method and ring-opening polymerization method.Direct polycondensation method is because gained polylactic acid molecule amount is not high, and gained poly(lactic acid) using value is not high, does not adopt usually.The report that direct polycondensation method prepares poly(lactic acid) sees USP2174491, USP2396994, USP2438208.At present, the method of ring-opening polymerization is generally adopted in the preparation of poly(lactic acid), promptly earlier with the oxide compound of amphoteric metal as catalyzer, zinc oxide for example, weisspiessglanz etc., or the halogenide of tellurium, zinc chloride for example, antimonic fluorides etc. become the lower oligopolymer of molecular weight with lactic acid polymerizes, under high temperature, high vacuum, oligopolymer is cracked into rac-Lactide then, as the report among DRP267826, DD53074, DE1083275, the DE07501.The organic compound that second step was used tellurium makes the lactide ring-opening polymerization become macromolecular compound as catalyzer.This class report sees Brit1007347, Brit932392, Fr142533, DD36499, DE1112293.In ring-opening polymerization, the purity of lactide is the most important factor of decision polymericular weight, obtain high molecular weight polymers, must select for use highly purified lactide as raw material.But produce in the technology of rac-Lactide at the Pintsch process lactic acid oligomers that adopts usually at present, one time yield is lower, and the gained lactide is yellow, purity is not high, need repeatedly recrystallization just can obtain the higher lactide of purity, this just makes the total productive rate of lactide low, the cost height.
[summary of the invention]
Purpose of the present invention provides a kind of preparation method who is used for the raw material rac-Lactide of synthesizing polylactic acid for solving the low problem of rac-Lactide productive rate, and its step is as follows:
A, dewater: adopt the method for underpressure distillation after the first air distillation to remove moisture content in the lactic raw material, reflux temperature is 60-180 ℃, and vacuum tightness is 0.1-200mmHg, and this process is an inert protective gas with nitrogen or argon gas;
B, the lactic acid after dewatering; in the presence of catalyzer and azeotropic solvent, reflux for a long time; here azeotropic solvent also is the good solvent of lactide, and most of water that generates is earlier told by water separator in this process, and the small portion water that the back the generates tower that is dried absorbs; reflux temperature is 100-160 ℃; reaction thoroughly back is steamed except that azeotropic solvent, and underpressure distillation then steams the lactide in the system at a lower temperature; obtain highly purified white lactide, this process is an inert protective gas with nitrogen or argon gas.
The present invention makes lactic acid reaction for a long time in the good solvent of lactide, directly is condensed into rac-Lactide, has avoided the technology of lactic acid oligomers Pintsch process, thereby has improved the yield and the purity of product greatly, is worthy of popularization.
[embodiment]
Below in conjunction with example the present invention is elaborated, this technology of preparing is still more clearly concerning this professional people, also can be applicable to the technical field of preparation glycollide.
Lactic raw material of the present invention can be optically active (as: D-or L-lactic acid), also can right and wrong optically active (promptly being D, L-lactic acid), and the purity of lactic raw material is 40-99.5%.
In the dewatering process, adopt fractional column, utilize the method for refluxed evaporator to remove moisture content in the lactic raw material under protection of inert gas, temperature for removing water is 60-180 ℃, and optimum is 100-160 ℃, and vacuum tightness is 0.1-200mmHg.
In the condensation reaction dewatering process, the high-pure lactic acid after dewatering refluxes under the condition of azeotropic solvent and catalyzer existence for a long time, and temperature is 80-200 ℃, is optimum with 100-180 ℃; Being chosen in of azeotropic solvent has a special requirement here: it must be the good solvent of lactide, and be the poor solvent of lactic acid oligomers, according to chemical equilibrium theory, in this solvent, reaction helps carrying out to the direction of direct generation rac-Lactide, and used azeotropic solvent is a kind of or wherein any two or more the mixed solvent in the pentanone that satisfies above principle, hexanone, heptanone, 4-methyl-3-amylene-2-ketone, 4-methyl-2 pentanone, toluene, dimethylbenzene, trimethylbenzene, phenylate, dimethyl phenylate, benzyl benzene ditane, the diphenylethane; Preparation is optimum with the phenylate during rac-Lactide, in the reflux course, the water that generate early stage is told by water separator, return reactor after the packing tower condensation dehydration of the azeotropic solvent that later stage steams through being filled with siccative, water-retaining agent, used catalyzer is the oxide compound of tellurium, for example zinc oxide, stannic oxide, weisspiessglanz and plumbous oxide etc. wherein are optimum with the weisspiessglanz; React thoroughly back steaming except that azeotropic solvent, underpressure distillation gets white solid, and distillation temperature is 120-200 ℃, and optimum is 160-180 ℃, and vacuum tightness is 0.01-10mmHg.
[specific embodiment]
Embodiment 1:
In the there-necked flask of the 1L that is furnished with thermometer, the D that adds 600g88%, L-lactic acid, and be positioned in the oil bath pan, temperature rises to 120 ℃, after this there is water to steam, go out water speed after about 3 hours and slow down, system temperature continues to rise, and slowly is evacuated to 100mmHg, temperature rises to 150 ℃ after 2 hours, gets high purity lact-acid oligomer 519g; The 519g lact-acid oligomer that obtains changed over to be furnished with thermometer, nitrogen ingress pipe, condenser, water trap, in the reactor of the 3L of molecular sieve filling drying tower, add 1.5L toluene and 1.03g antimonous oxide again, logical nitrogen, reflux, after 6 hours, no longer include water droplet in the water separator and form, open the drying tower piston this moment, continue to reflux 24 hours, steam then and remove toluene, underpressure distillation under nitrogen atmosphere, oil bath temperature are 175 ℃, and vacuum tightness is 5mmHg, collect 155-158 ℃ cut, obtain purity and be 96% white D, L-rac-Lactide 281g is 71.4% of theoretical yield.
Embodiment 2:
Experimental installation is identical with embodiment 1 with condition, replaces D with L-lactic acid, L-lactic acid, and vacuum tightness is 5mmHg, collects 154-158 ℃ of cut, getting purity is 96% white L-rac-Lactide 297g, is 71.5% of theoretical yield.
Embodiment 3:
Experimental installation is identical with embodiment one, and with the oxyacetic acid replacement D of 600g98%, L-lactic acid replaces toluene with 4-methyl-2 pentanone, and vacuum tightness is 5mmHg, collects 148-152 ℃ of cut, gets glycollide 268g, is 65% of theoretical yield.
Claims (8)
1, a kind of method for preparing rac-Lactide is characterized in that may further comprise the steps:
A, dewater: under protection of inert gas, the decompression dehydration method is removed the moisture in the lactic acid behind the first normal pressure, 100～200 ℃ of reflux temperature controls, and vacuum tightness is 0.01-200mmHg;
B, contract and react: the lactic acid after dewatering refluxes under protection of inert gas after adding catalyzer and azeotropic solvent for a long time, and discharge the water that reaction generates by water separator, the reflux course later stage allows azeotropic solvent by molecule plug drying tower, thoroughly to remove the water in the system, 100～200 ℃ of reflux temperature controls; Decompression or normal pressure steam and desolventize, and underpressure distillation gets rac-Lactide under protection of inert gas again, 120～200 ℃ of temperature controls, and vacuum tightness is 0.1～10mmHg.
2, a kind of method for preparing rac-Lactide as claimed in claim 1 is characterized in that said lactic raw material is an optical activity or non-optical active, and the purity of lactic raw material is 10%～99.5%.
3, a kind of method for preparing rac-Lactide as claimed in claim 1 is characterized in that used azeotropic solvent must be the good solvent of lactide, is the poor solvent of oligopolymer simultaneously, and in this solvent, reaction helps carrying out to the direction of direct generation rac-Lactide; Used azeotropic solvent is specially pentanone, pimelinketone, heptanone, acetyl-acetone, 4-methyl-3-amylene-2-ketone, 4-methyl-2 pentanone, toluene, dimethylbenzene, trimethylbenzene, phenylate, dimethyl phenylate, benzyl phenylate, ditane, the diphenylethane, 1 that satisfies above principle, 1-toluylene, 4-isopropyl-phenol or wherein any two or more mixture.
4, a kind of method for preparing rac-Lactide as claimed in claim 1 is characterized in that said catalyzer can be the oxide compound of amphoteric metal compound, specifically adopts antimonous oxide, zinc oxide, stannic oxide, plumbous oxide etc.
5, a kind of method for preparing rac-Lactide as claimed in claim 1, it is characterized in that contracting and react in reaction times be 4～48 hours.
6, a kind of method for preparing rac-Lactide as claimed in claim 1 is characterized in that the mass ratio between lactic acid and the catalyzer is 5～10000: 1.
7, a kind of method for preparing rac-Lactide as claimed in claim 1, the volume ratio that it is characterized in that lactic acid and azeotropic solvent is 1: 1～15.
8, a kind of method for preparing rac-Lactide as claimed in claim 1 can also be applied in the technical field of preparation glycollide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA03142029XA CN1488628A (en) | 2003-08-01 | 2003-08-01 | Method for preparing lactide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA03142029XA CN1488628A (en) | 2003-08-01 | 2003-08-01 | Method for preparing lactide |
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| CN1488628A true CN1488628A (en) | 2004-04-14 |
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| CNA03142029XA Pending CN1488628A (en) | 2003-08-01 | 2003-08-01 | Method for preparing lactide |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102675277A (en) * | 2012-04-24 | 2012-09-19 | 南阳理工学院 | Method for preparing lactide by catalytic method under reduced pressure |
| CN101747314B (en) * | 2009-12-25 | 2013-02-13 | 南开大学 | Process method for synthesizing L-lactide by molecular sieve catalytic pyrolysis method |
| CN101925591B (en) * | 2007-12-26 | 2013-12-04 | 克坦顿有限公司 | Process for production of cyclic diesters of alpha-hydroxyacids |
| CN107324989A (en) * | 2017-06-09 | 2017-11-07 | 安徽丰原发酵技术工程研究有限公司 | It is a kind of by being dehydrated the method that extraction prepares lactic acid and lactide |
| WO2018176884A1 (en) * | 2017-03-28 | 2018-10-04 | 南京大学 | Method for producing optically pure l-/d-lactide with all-green closed cycle process |
| 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 |
| TWI700279B (en) * | 2015-02-13 | 2020-08-01 | 普拉克生化公司 | Method for manufacturing lactide |
| CN112939933A (en) * | 2021-02-26 | 2021-06-11 | 中国科学院长春应用化学研究所 | Thiactide monomer based on lactic acid or amino acid, recoverable polythioester and preparation method |
| CN113651794A (en) * | 2021-09-15 | 2021-11-16 | 珠海格力新材料有限公司 | Lactide synthesis method |
| CN114621179A (en) * | 2022-03-17 | 2022-06-14 | 中国神华煤制油化工有限公司 | Method for synthesizing glycolide |
| CN115028615A (en) * | 2022-07-27 | 2022-09-09 | 万华化学(四川)有限公司 | L, L-lactide and preparation method and application thereof |
| CN115253994A (en) * | 2022-08-25 | 2022-11-01 | 陕西德信祥能源科技有限公司 | Device and method for preparing lactide |
-
2003
- 2003-08-01 CN CNA03142029XA patent/CN1488628A/en active Pending
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101925591B (en) * | 2007-12-26 | 2013-12-04 | 克坦顿有限公司 | Process for production of cyclic diesters of alpha-hydroxyacids |
| CN101747314B (en) * | 2009-12-25 | 2013-02-13 | 南开大学 | Process method for synthesizing L-lactide by molecular sieve catalytic pyrolysis method |
| CN102675277A (en) * | 2012-04-24 | 2012-09-19 | 南阳理工学院 | Method for preparing lactide by catalytic method under reduced pressure |
| TWI700279B (en) * | 2015-02-13 | 2020-08-01 | 普拉克生化公司 | Method for manufacturing lactide |
| 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 |
| WO2018176884A1 (en) * | 2017-03-28 | 2018-10-04 | 南京大学 | Method for producing optically pure l-/d-lactide with all-green closed cycle process |
| CN110845326A (en) * | 2017-06-09 | 2020-02-28 | 安徽丰原发酵技术工程研究有限公司 | Method for preparing lactic acid and lactide by dehydration extraction |
| CN107324989A (en) * | 2017-06-09 | 2017-11-07 | 安徽丰原发酵技术工程研究有限公司 | It is a kind of by being dehydrated the method that extraction prepares lactic acid and lactide |
| CN112939933A (en) * | 2021-02-26 | 2021-06-11 | 中国科学院长春应用化学研究所 | Thiactide monomer based on lactic acid or amino acid, recoverable polythioester and preparation method |
| CN113651794A (en) * | 2021-09-15 | 2021-11-16 | 珠海格力新材料有限公司 | Lactide synthesis method |
| CN114621179A (en) * | 2022-03-17 | 2022-06-14 | 中国神华煤制油化工有限公司 | Method for synthesizing glycolide |
| CN114621179B (en) * | 2022-03-17 | 2024-03-26 | 中国神华煤制油化工有限公司 | synthesis method of glycolide |
| CN115028615A (en) * | 2022-07-27 | 2022-09-09 | 万华化学(四川)有限公司 | L, L-lactide and preparation method and application thereof |
| CN115028615B (en) * | 2022-07-27 | 2024-01-09 | 万华化学(四川)有限公司 | L, L-lactide and preparation method and application thereof |
| CN115253994A (en) * | 2022-08-25 | 2022-11-01 | 陕西德信祥能源科技有限公司 | Device and method for preparing lactide |
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