CN1260223C - Process for preparation of lactide by using ionic liquid as catalyst - Google Patents
Process for preparation of lactide by using ionic liquid as catalyst Download PDFInfo
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- CN1260223C CN1260223C CN 200410013456 CN200410013456A CN1260223C CN 1260223 C CN1260223 C CN 1260223C CN 200410013456 CN200410013456 CN 200410013456 CN 200410013456 A CN200410013456 A CN 200410013456A CN 1260223 C CN1260223 C CN 1260223C
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- ionic liquid
- acid
- lactide
- charged ion
- alpha hydroxy
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Abstract
The present invention relates to a process for preparing lactide by using an ionic liquid as a catalyst, which comprises: alpha-carboxylic acid is subjected to polycondensation reaction at 50 to 150 DEG C and 1Pa to 0.01MPa to produce low-polymerization alpha-carboxylic acid with the polymerization degree of 2 to 30; then, the low-polymerization alpha-carboxylic acid is depolymerized into the lactide in the presence of the ionic liquid as the catalyst and a reaction medium at 50 to 150 DEG C and 1Pa to 0.01MPa, and the quality ratio of the ionic liquid to the oligomerization alpha-carboxylic acid is from 1: 1000 to 1000: 1. The method has the following advantages that firstly, the ionic liquid can obviously accelerate the speed rate of polycondensation reaction and depolymerization reaction; the reaction can be completed in a short time; secondly, the ionic liquid can reduce the viscidity of the reaction system and improve the system mass transfer and the heat transfer condition; and thirdly, the ionic liquid replaces inflammable and highly toxic ordinary organic solvents, and accordingly, the manufacturing process of the lactide is more efficient and safer.
Description
Technical field
The present invention relates to the method for ionic liquid-catalyzed manufacturing lactide, belong to the organic synthesis field.
Background technology
The structure of the lactide that the present invention relates to is as follows:
R=H,CH
3
Compound is a glycollide when R=H, R=CH
3The time compound be rac-Lactide.In this manual, will in the chemical structural formula of lactide, not show its steric configuration when relating to the steric configuration of lactide, only in narration, replace with words such as left-handed, dextrorotation, racemize and mesos.
Lactide is a monomer of making the poly-alpha hydroxy acid of high molecular degradable polyester, generally is that the thermal degradation from oligomeric alpha hydroxy acid obtains.Classical lactide synthetic method, as United States Patent (USP) (US Pat.6277951B1,5374743) and world patent (WO02083661) described: alpha hydroxy acid is placed polycondensation obtains low-molecular-weight poly-alpha hydroxy acid under the effect of certain process conditions and catalyzer, low-molecular-weight poly-alpha hydroxy acid thermo-cracking can be obtained lactide.Yet there is important disadvantages in this method, promptly preparing in the process of lactide in cracking causes material to conduct heat slowly because of reactant viscosity constantly increases easily, system is heated inhomogeneous, and local temperature is too high, and the result causes side reactions such as the decline of lactide productive rate, optical activity 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 lactide become dangerous.
Ionic liquid at room temperature claims room temperature fused salt again, is a kind of in room temperature or be bordering on the ionic compound that is in a liquid state under the room temperature.Ionic liquid generally has some particular performances, as the use temperature of lower fusing point, adjustable lewis acidity, negligible vapour pressure, broad and special solvability etc.And ionic liquid at room temperature is easy to reach with reaction product by means such as distillations and separates.In recent ten years, by nitrogen-containing heterocycle compound such as halogenated alkyl pyridine, halogenation 1,3-alkyl imidazole synthetic ionic liquid has received increasing attention as a kind of catalyzer, solvent and heat-transfer medium of cleaning.
Summary of the invention
Problem to be solved by this invention provides a kind of method of ionic liquid-catalyzed manufacturing lactide, and this method is safety not only, and can obviously accelerate the speed of polycondensation and depolymerization reaction, reduces the viscosity of reaction system, improves system mass transfer and heat transfer conditions.
Technical scheme provided by the invention is: a kind of method of ionic liquid-catalyzed manufacturing lactide, polycondensation takes place under 50~150 ℃, 1Pa~0.01MPa condition alpha hydroxy acid, and to generate the polymerization degree be 2~30 oligomeric alpha hydroxy acid, under 150~250 ℃, 1Pa~0.01MPa condition, be catalyzer and reaction medium with oligomeric alpha hydroxy acid then, be cracked into lactide with the ionic liquid; The mass ratio of ionic liquid and oligomeric alpha hydroxy acid is 1: 1000~1000: 1.
The polycondensation of above-mentioned alpha hydroxy acid is catalyzer and reaction medium with the ionic liquid, and the mass ratio of ionic liquid and alpha hydroxy acid is 1: 1000~1000: 1.
The present invention uses ionic liquid to be catalyzer and reaction medium, and the thermo-cracking of polycondensation of catalysis alpha hydroxy acid and oligomeric alpha hydroxy acid is made lactide.Ionic liquid is not only catalysts, and serves as reaction medium; The alpha hydroxy acid raw material that adopts is any one in oxyacetic acid, D-lactic acid, dextrolactic acid or the racemic lactic acid; The final lactide of making can be glycollide, levorotatory lactide, dextrorotation rac-Lactide or rac-lactide; Alpha hydroxy acid polycondensation and oligomeric alpha hydroxy acid cracking are all carried out under heating and vacuum decompression condition; Ionic liquid can add in the process of oligomeric alpha hydroxy acid cracking manufacturing lactide, also can add when the alpha hydroxy acid polycondensation becomes oligomeric alpha hydroxy acid.
The ionic liquid that uses among the present invention is made up of positively charged ion and negatively charged ion two portions, and forming ionic liquid cationic can be 1,3-dialkylimidazolium ion [R
1R
3Im], alkyl pyridine ion (Py), quaternary amine ion (NR
4); Forming ionic liquid anionic can be Tetrafluoroboric acid negatively charged ion (BF
4), phosphofluoric acid negatively charged ion (PF
6), trifluoromethane sulfonic acid negatively charged ion (OTf), D-lactic acid negatively charged ion (LLA), dextrolactic acid negatively charged ion (DLA); The alkyl substituent of forming on cationic nitrogen heterocyclic ring and the aminated compounds can be C
1-C
18The alkyl of linear or branching.
This method has the following advantages and positively effect: at first, ionic liquid can obviously be accelerated the speed of polycondensation and depolymerization reaction, and reaction is accomplished at short notice; Secondly, ionic liquid can reduce the viscosity of reaction system, improves system mass transfer and heat transfer conditions; Once more, inflammable, highly toxic ordinary organic solvents that ionic liquid has substituted makes that the lactide manufacturing processed is more efficient, safety.
Embodiment
Below be embodiments of the invention, these embodiment should not be counted as limitation of the present invention.
Embodiment 1.
With 76 gram oxyacetic acids and 152 gram [R
1R
3Im] [BF
4] mix and drop into 250 milliliters round-bottomed flask, induction stirring, to obtain the polymerization degree in 1 hour be 10 low polyglycolic acid to vacuum decompression under 150 ℃ and 0.01MPa, keep same vacuum tightness, elevated temperature to 215 ℃ makes low polyglycolic acid generation thermo-cracking, the glycollide crude product that underpressure distillation goes out to generate, crude product filters and obtains white glycollide 55 grams, productive rate 95% through re-crystallizing in ethyl acetate.
Embodiment 2.
Racemic lactic acid and 48 gram [R with 600 grams 85%
1R
3Im] [OT
f] mix and drop into 1000 milliliters round-bottomed flask, induction stirring, to obtain the polymerization degree in 1 hour be 2 oligomeric racemic lactic acid to vacuum decompression under 50 ℃ and 0.001MPa, keep same vacuum tightness, elevated temperature to 180 ℃ makes oligomeric racemic lactic acid generation thermo-cracking, the rac-lactide crude product that underpressure distillation goes out to generate, the crude product washing with alcohol is filtered and is obtained white racemize lactide 201 grams, productive rate 49%.
Embodiment 3.
D-lactic acid and 240 gram [R with 600 grams 85%
1R
3Im] [PF
6] mix and drop into 1000 milliliters round-bottomed flask, induction stirring, to obtain the polymerization degree in 1 hour be 12 low PLLA to vacuum decompression under 140 ℃ and 0.001MPa, keep same vacuum tightness, elevated temperature to 180 ℃ makes low PLLA generation thermo-cracking, the levorotatory lactide crude product that underpressure distillation goes out to generate, crude product obtains white levorotatory lactide 388 grams, productive rate 95% after filtration.
Embodiment 4.
600 grams, 85% dextrolactic acid is dropped into 1000 milliliters round-bottomed flask, induction stirring, to obtain the polymerization degree in 1 hour be 6 oligomeric dextrolactic acid to vacuum decompression under 110 ℃ and 0.01MPa, keeps same vacuum tightness, elevated temperature to 165 ℃, add 120 gram [Py] [DLA], make oligomeric dextrolactic acid generation thermo-cracking, the dextrorotation rac-Lactide crude product that underpressure distillation goes out to generate, crude product is through re-crystallizing in ethyl acetate, filtration obtains white dextrorotation rac-Lactide 360 grams, productive rate 88%.
Embodiment 5.
600 grams, 85% D-lactic acid is dropped into 1000 milliliters round-bottomed flask, induction stirring, to obtain the polymerization degree in 1 hour be 12 low PLLA to vacuum decompression under 140 ℃ and 0.001MPa, keeps same vacuum tightness, elevated temperature to 165 ℃ adds 100 gram [NR
4] [OTf], making low PLLA generation thermo-cracking, the levorotatory lactide crude product that underpressure distillation goes out to generate, crude product filter and obtain white levorotatory lactide 368 grams, productive rate 90% through re-crystallizing in ethyl acetate.
Embodiment 6.
D-lactic acid and 250 gram [NR with 600 grams 85%
4] [LLA] mix to drop into 1000 milliliters round-bottomed flask, induction stirring, to obtain the polymerization degree in 1 hour be 30 the oligomeric left-handed lactic acid that revolves to vacuum decompression under 100 ℃ and 1MPa, keep same vacuum tightness, elevated temperature to 180 ℃ makes oligomeric outer D-lactic acid generation thermo-cracking, the levorotatory lactide crude product that underpressure distillation goes out to generate, the crude product washing with alcohol is filtered and is obtained white levorotatory lactide 460 grams, productive rate 96%.
Used ionic liquid is the commercially available prod in the foregoing description.Can obtain identical result with used ionic liquid in other ionic liquids replacement the foregoing descriptions of the present invention.
Claims (5)
1. the method for an ionic liquid-catalyzed manufacturing lactide, it is characterized in that: polycondensation takes place under 50~150 ℃, 1Pa~0.01MPa condition alpha hydroxy acid, and to generate the polymerization degree be 2~30 oligomeric alpha hydroxy acid, under 150~250 ℃, 1Pa~0.01MPa condition, be catalyzer and reaction medium with oligomeric alpha hydroxy acid then, be cracked into lactide with the ionic liquid; The mass ratio of ionic liquid and oligomeric alpha hydroxy acid is 1: 0.5~10.625.
2. method according to claim 1 is characterized in that: the polycondensation of alpha hydroxy acid is catalyzer and reaction medium with the ionic liquid, and the mass ratio of ionic liquid and alpha hydroxy acid is 1: 0.5~1000.
3. method according to claim 1 and 2 is characterized in that: the alpha hydroxy acid of employing is oxyacetic acid, D-lactic acid, dextrolactic acid or racemic lactic acid.
4. method according to claim 1 and 2 is characterized in that: ionic liquid is by positively charged ion and negatively charged ion ionic compound dimerous; The ionic liquid positively charged ion is selected from 1,3-dialkylimidazolium ion, alkyl pyridine ion, quaternary amine ion; The ionic liquid negatively charged ion is selected from Tetrafluoroboric acid negatively charged ion, phosphofluoric acid negatively charged ion, trifluoromethane sulfonic acid negatively charged ion, D-lactic acid negatively charged ion, dextrolactic acid negatively charged ion.
5. method according to claim 4 is characterized in that: the alkyl substituent on cationic nitrogen heterocyclic ring of ionic liquid and the aminated compounds is C
1-C
18The alkyl of linear or branching.
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CN 200410013456 CN1260223C (en) | 2004-07-13 | 2004-07-13 | Process for preparation of lactide by using ionic liquid as catalyst |
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CN 200410013456 CN1260223C (en) | 2004-07-13 | 2004-07-13 | Process for preparation of lactide by using ionic liquid as catalyst |
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CN1594312A CN1594312A (en) | 2005-03-16 |
CN1260223C true CN1260223C (en) | 2006-06-21 |
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Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
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CN104892564B (en) * | 2015-06-04 | 2017-07-07 | 中国科学院长春应用化学研究所 | A kind of method that poly-lactic acid in high molecular weight prepares lactide |
CN105646441A (en) * | 2016-03-11 | 2016-06-08 | 东华大学 | Method for preparing lactide |
CN114957196B (en) * | 2022-05-06 | 2023-11-14 | 哈尔滨工业大学(威海) | Method for synthesizing diester-based cyclic ester by catalysis of ionic liquid analogue |
CN115650948B (en) * | 2022-11-01 | 2023-12-19 | 中国科学院长春应用化学研究所 | Preparation method of glycolide-lactide |
CN115745946B (en) * | 2022-11-01 | 2024-03-26 | 中国科学院长春应用化学研究所 | Low-temperature preparation method of glycolide and lactide |
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