CN103922933A - Preparation method of ethyl lactate - Google Patents
Preparation method of ethyl lactate Download PDFInfo
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- CN103922933A CN103922933A CN201410165748.7A CN201410165748A CN103922933A CN 103922933 A CN103922933 A CN 103922933A CN 201410165748 A CN201410165748 A CN 201410165748A CN 103922933 A CN103922933 A CN 103922933A
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- ethyl lactate
- lactide
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- ethanol
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/03—Preparation of carboxylic acid esters by reacting an ester group with a hydroxy group
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/30—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group
- C07C67/31—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by introduction of functional groups containing oxygen only in singly bound form
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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
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- Chemical & Material Sciences (AREA)
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- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
The invention provides a preparation method of an ethyl lactate and belongs to the fields of the synthesis of organic solvents and green chemical industry. The preparation method of the ethyl lactate solves the problems of low product yield, entrainment of toxic solvents in products, poor quality of products and the like of a traditional ethyl lactate synthesis method. The method comprises the steps of reacting a lactide with ethanol in the presence of a catalyst under a heating reflux condition, and then carrying out reduced pressure distillation and purification to obtain the ethyl lactate. The major ingredient of the after-cut of distillation is lactyl ethyl lactate which is capable of continuously reacting with the ethanol distilled out to further generate the ethyl lactate; the total conversation rate of the lactide in the two reactions is more than 98%. The method has the advantages of high reaction speed, mild conditions, easy separation of raw materials and product and high quality of product, and is safe and environmental friendly.
Description
Technical field
The invention belongs to the synthetic and green chemical industry field of organic solvent, be specifically related to a kind of preparation method of ethyl lactate.
Background technology
The molecular formula of ethyl lactate is C
5h
10o
3, fusing point-126 ℃, 154 ℃ of boiling points, can dissolve each other with water, are a kind of important industrial chemicals.Because it is nontoxic, solvability good, not volatile, the advantage such as biodegradable, as " green solvent " that have exploitation value, can be used for replacing traditional noxious solvent of current industrial use, as halo class, ethers, fluorochlorohydrocarbon kind solvent, as cleaned oil field pipe, preparing all kinds of high-grade paint etc.; Ethyl lactate is also a kind of flavouring agent, has aroma, for modulating various drinks and food flavour, also can be used in fodder industry as flavouring agent; In addition the lubricant of using as slugging in pharmaceutical industry, pharmaceutical intermediate etc.; Ethyl lactate has a wide range of applications in industry.
The synthetic esterification process that conventionally adopts of ethyl lactate, lactic acid and ethanol is dehydration reaction under an acidic catalyst exists, and generates ester, then carries out purifying by underpressure distillation.But ordinary method mainly contains two problems, the first is in order to obtain high as far as possible transformation efficiency, manage to remove the water that reaction generates, and impels reaction to carry out to positive dirction, conventionally adopts organic solvent that benzene, toluene etc. are poisonous as band aqua; Its two, the catalyzer of vitriol oil Chang Zuowei reaction, causes the shortcomings such as long reaction time, equipment corrosion is serious, by product is many, had a strong impact on the quality of product, and work brings difficulty to subsequent purification.
Rac-Lactide is the intermediate product of two-step approach production poly(lactic acid), and molecular formula is C
6h
10o
4, according to opticity, being divided into L-rac-Lactide, D-rac-Lactide and Study of Meso-Lactide, the acquisition of general rac-Lactide is oligomeric by lactic acid shrink, obtains the oligopolymer of lactic acid, then obtains rac-Lactide through cracking.General L lactic acid makes L rac-Lactide, and D lactic acid makes D rac-Lactide, but due to the easy racemization of rac-Lactide, has the generation of some Study of Meso-Lactide in producing rac-Lactide process.Because crystal property and the resistance toheat of poly(lactic acid) affected by opticity in polymkeric substance, for the rac-Lactide Study of Meso-Lactide too high levels of polymerization, can cause the degradation of poly(lactic acid), so the use of racemization rac-Lactide is restricted.And ethyl lactate does not have optically-active requirement as solvent or pharmaceutical intermediate etc., therefore with racemization rac-Lactide lactic acid producing in next life ethyl ester, both realized comprehensive utilization, again can the high-quality ethyl lactate of acquisition quick, high yield.
Summary of the invention
In order to solve, the lactic acid yield existing in traditional ethyl lactate synthetic method is low, carry the problems such as noxious solvent, poor product quality secretly in product, the invention provides a kind of preparation method of ethyl lactate.
The preparation method who the invention provides a kind of ethyl lactate, comprising:
Rac-Lactide and ethanol, under catalyst action, are reacted under reflux condition, then purify and obtain ethyl lactate through underpressure distillation.
Preferably, described rac-Lactide is selected from one or more in L rac-Lactide, D rac-Lactide or Study of Meso-Lactide.
Preferably, described ethanol is dehydrated alcohol.
Preferably, described catalyzer is Lewis acid or pink salt.
Preferably, described Lewis acid comprises tosic acid or aluminum chloride.
Preferably, described pink salt comprises stannous octoate, tin protochloride or benzoic acid stannous.
Preferably, described temperature of reaction is 80-100 ℃, and the reaction times is 2-10h.
Preferably, the mol ratio of described rac-Lactide and ethanol is 1:(2-10).
Preferably, described method also comprise by the after cut lactyllactic acid ethyl ester obtaining after underpressure distillation again with ethanol synthesis.
Beneficial effect of the present invention
The invention provides a kind of preparation method of ethyl lactate, the method under catalyst action, is reacted rac-Lactide and ethanol under reflux condition, then purifies and obtain through underpressure distillation.Method of the present invention obtains product except target product ethyl lactate and intermediate product lactyllactic acid ethyl ester, do not have other byproducts to generate, and lactyllactic acid ethyl ester can also further change into ethyl lactate, final product only has ethyl lactate, and the atom of participating in reaction in chemical reaction all enters into final product; Secondly, the raw materials used rac-Lactide of the present invention does not have optically-active requirement, both can be L rac-Lactide, D rac-Lactide, can also be racemization rac-Lactide, or the mixture of several rac-Lactides, the applied range of raw material, especially can will be unfavorable for that the racemization rac-Lactide of producing high-quality poly(lactic acid) re-uses production ethyl lactate, both realize the comprehensive utilization of raw material, and also can reach the maximization of economic benefit, had quite high economic worth; Again, rac-Lactide and ethanol synthesis, the transformation efficiency of rac-Lactide is high, can reach more than 98%, the reuse repeatedly of excessive ethanol, production cost is low.In addition, by rac-Lactide and the direct Synthesis of ethyl lactate of ethanol, due to aspect boiling point, ethanol, ethyl lactate, lactyllactic acid ethyl ester and rac-Lactide differ larger, product is easy to obtain purifying by distillation, does not also have other solvent to participate in reaction, can obtain highly purified ethyl lactate product.
Embodiment
The preparation method who the invention provides a kind of ethyl lactate, comprising:
Rac-Lactide and ethanol, under catalyst action, are reacted under reflux condition, then purify and obtain ethyl lactate through underpressure distillation.
According to the present invention, the described transesterification reaction that is mainly, reaction process is carried out in two steps: rac-Lactide elder generation and a part ethanol synthesis, open loop generates lactyllactic acid ethyl ester, lactyllactic acid ethyl ester again with another molecules of ethanol generation transesterify, generate bimolecular ethyl lactate, wherein the first step speed of response is very fast, the second step of reaction is rate-limiting step, and its reaction process is as follows:
According to the present invention, described does not have optically-active requirement to rac-Lactide raw material, is preferably selected from one or more in L rac-Lactide, D rac-Lactide or Study of Meso-Lactide.Described ethanol is preferably dehydrated alcohol, both mixtures is added to catalyzer post-heating back flow reaction under anhydrous condition, until reaction reaches balance, stops the introducing of water, to reduce the hydrolysis of rac-Lactide and the generation of by product lactic acid in reaction process.
According to the present invention, described catalyzer is preferably Lewis acid or pink salt.Described Lewis acid preferably includes tosic acid or aluminum chloride; Described pink salt preferably includes stannous octoate, tin protochloride or benzoic acid stannous.Described catalytic amount is preferably the 0.1-3% of rac-Lactide quality.
According to the present invention, described reflux refers to the mixing solutions of rac-Lactide and ethanol, under normal pressure, is heated to azeotropic, steams gas phase part and after cooling water condensation, is back to continuation participation reaction in reaction flask again, described temperature of reaction is preferably 80-100 ℃, more preferably 85-95 ℃; Reaction times is preferably 2-10h, more preferably 6-8h.
According to the present invention, described rac-Lactide and the mol ratio of ethanol are preferably as 1:(2-10), 1:(4-8 more preferably), the transformation efficiency height of single reaction rac-Lactide with add the amount of ethanol relevant, add the amount of ethanol more, while reaching balance, the content of lactyllactic acid ethyl ester is lower, while reaching balance, the content of rac-Lactide changes not quite, it is main because the first step reaction is rapid reaction, and the energy of lactyllactic acid ethyl ester is lower, stable compared with rac-Lactide, during balance, the content of rac-Lactide is very low, react more abundant, and the speed of lactyllactic acid ethyl ester and ethanol synthesis is lower, Gibbs free energy between product and reactant is more or less the same, by adding into the way of ethanol, reaction forward to be carried out, improve single reaction lactide conversions, the add-on of ethanol should take into full account energy consumption and reaction conversion ratio balance between the two simultaneously, realize minimization of cost.
According to the present invention, after described reflux, obtain reaction solution, carry out distillation purifying, because the boiling point of reactant and product differs greatly, distillation purifying is easy to, because the boiling point of ethyl lactate is higher, still-process should under reduced pressure carry out, first steam ethanol, steam subsequently ethyl lactate, remaining is after cut.The ethanol steaming can utilize again, reacts Synthesis of ethyl lactate with rac-Lactide.
According to the present invention, the described after cut distilling out is mainly lactyllactic acid ethyl ester, and a small amount of ethyl lactate, contains a small amount of unreacted rac-Lactide in addition.Preferred described method also comprise by the after cut lactyllactic acid ethyl ester obtaining after underpressure distillation again with ethanol synthesis Synthesis of ethyl lactate, finally raw material rac-Lactide all can be changed into ethyl lactate, theoretical yield reaches 100%.
Below in conjunction with specific embodiment, the present invention is done to further detailed description, the raw material relating in embodiment is commercially available.
Embodiment 1
In the there-necked flask of 1000mL, add 214.5gL lactide powder, add again 6g tosic acid as catalyzer and induction stirring, side mouth of there-necked flask inserts thermometer, another side mouth is equipped with constant pressure funnel, 280g dehydrated alcohol is housed, middle port connects spherical condenser, upper end of condenser connects nitrogen ball, guarantee system sealing normal pressure, after first system being vacuumized, pass into nitrogen, three times so repeatedly, next ethanol is splashed in there-necked flask, start to stir and heating, at 85 ℃, atmospheric pressure reflux is 6 hours, after end, composition with gas chromatographic analysis reaction solution, show that the amount that remains rac-Lactide in reactant is less than 0.5%, the transformation efficiency of primary first-order equation ethyl lactate reaches 91.9%, the amount that is converted into lactyllactic acid ethyl ester is 7.4%, the transformation efficiency that obtains ethyl lactate after reaction finishes is as shown in table 1.
In order to improve transformation efficiency, by the distillation of primary first-order equation liquid, reclaim ethanol, target product is separated from reaction solution, then by the ethanol and the after cut reflux that reclaim, under identical condition, carried out secondary reaction.
Concrete operation method is: above-mentioned reaction solution is carried out to underpressure distillation, difference extraction ethanol 131g, ethyl lactate 322g, after cut 45g, the after cut overwhelming majority is lactyllactic acid ethyl ester, contain a small amount of ethyl lactate, catalyzer, also has a small amount of rac-Lactide and other impurity in addition.The ethanol steaming is joined in this after cut, after dissolving completely, with the content of gas Chromatographic Determination ethyl lactate, so as with react after contrast, wherein have 6.1% ethyl lactate existence.By this mixed solution, by method reflux as previously mentioned 6 hours, after refluxing and finishing, the content that records ethyl lactate in reaction solution was 92.3%, and the lactyllactic acid ethyl ester and the ethanol synthesis that in after cut, have 86.3% are described, was further converted to ethyl lactate.Comprehensive two secondary responses, have 98.3% rac-Lactide and finally change into ethyl lactate.
Embodiment 2
In the there-necked flask of 1000mL, add 215gD lactide powder, add again 6g tosic acid as catalyzer and induction stirring, side mouth of there-necked flask inserts thermometer, another side mouth is equipped with constant pressure funnel, 138g dehydrated alcohol is housed, middle port connects spherical condenser, upper end of condenser connects nitrogen ball, guarantee system sealing normal pressure, after first system being vacuumized, pass into nitrogen, three times so repeatedly, next ethanol is splashed in there-necked flask, start to stir and heating, at 95 ℃, atmospheric pressure reflux is 6 hours, after end, composition with gas chromatographic analysis reaction solution, result is as shown in table 1.
Embodiment 3
In the there-necked flask of 1000mL, add 215g Study of Meso-Lactide powder, add again 6g tosic acid as catalyzer and induction stirring, side mouth of there-necked flask inserts thermometer, another side mouth is equipped with constant pressure funnel, 414g dehydrated alcohol is housed, middle port connects spherical condenser, upper end of condenser connects nitrogen ball, guarantee system sealing normal pressure, after first system being vacuumized, pass into nitrogen, three times so repeatedly, next ethanol is splashed in there-necked flask, start to stir and heating, at 90 ℃, atmospheric pressure reflux is 8 hours, after end, composition with gas chromatographic analysis reaction solution, result is as shown in table 1.
Embodiment 4
In the there-necked flask of 1000mL, add 215gL lactide powder, add again 6g tosic acid as catalyzer and induction stirring, side mouth of there-necked flask inserts thermometer, another side mouth is equipped with constant pressure funnel, 552g dehydrated alcohol is housed, middle port connects spherical condenser, upper end of condenser connects nitrogen ball, guarantee system sealing normal pressure, after first system being vacuumized, pass into nitrogen, three times so repeatedly, next ethanol is splashed in there-necked flask, start to stir and heating, at 90 ℃, atmospheric pressure reflux is 6 hours, after end, composition with gas chromatographic analysis reaction solution, result is as shown in table 1.
Table 1
The explanation of above embodiment is just for helping to understand method of the present invention and core concept thereof.It should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention, can also carry out some improvement and modification to the present invention, these improvement and modification also fall in the protection domain of the claims in the present invention.
Above-mentioned explanation to the disclosed embodiments, makes professional and technical personnel in the field can realize or use the present invention.To the multiple modification of these embodiment, will be apparent for those skilled in the art, General Principle as defined herein can, in the situation that not departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention will can not be restricted to these embodiment shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (9)
1. a preparation method for ethyl lactate, is characterized in that, comprising:
Rac-Lactide and ethanol, under catalyst action, are reacted under reflux condition, then purify and obtain ethyl lactate through underpressure distillation.
2. the preparation method of a kind of ethyl lactate according to claim 1, is characterized in that, described rac-Lactide is selected from one or more in L rac-Lactide, D rac-Lactide or Study of Meso-Lactide.
3. the preparation method of a kind of ethyl lactate according to claim 1, is characterized in that, described ethanol is dehydrated alcohol.
4. the preparation method of a kind of ethyl lactate according to claim 1, is characterized in that, described catalyzer is Lewis acid or pink salt.
5. the preparation method of a kind of ethyl lactate according to claim 4, is characterized in that, described Lewis acid comprises tosic acid or aluminum chloride.
6. the preparation method of a kind of ethyl lactate according to claim 4, is characterized in that, described pink salt comprises stannous octoate, tin protochloride or benzoic acid stannous.
7. the preparation method of a kind of ethyl lactate according to claim 1, is characterized in that, described temperature of reaction is 80-100 ℃, and the reaction times is 2-10h.
8. the preparation method of a kind of ethyl lactate according to claim 1, is characterized in that, described rac-Lactide and the mol ratio of ethanol are 1:(2-10).
9. the preparation method of a kind of ethyl lactate according to claim 1, is characterized in that, described method also comprise by the after cut lactyllactic acid ethyl ester obtaining after underpressure distillation again with ethanol synthesis.
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| CN201410165748.7A CN103922933A (en) | 2014-04-22 | 2014-04-22 | Preparation method of ethyl lactate |
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| CN201410165748.7A CN103922933A (en) | 2014-04-22 | 2014-04-22 | Preparation method of ethyl lactate |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104803844A (en) * | 2015-03-27 | 2015-07-29 | 中国科学院长春应用化学研究所 | Method for preparing lactate from waste containing polylactic acid chain segments |
| CN105061201A (en) * | 2015-07-31 | 2015-11-18 | 福建农林大学 | Preparation method of lactic ester |
| CN112552168A (en) * | 2020-12-16 | 2021-03-26 | 盐城市春竹香料有限公司 | Process method for preparing ethyl lactate by rectification |
| CN112707851A (en) * | 2015-11-12 | 2021-04-27 | 诺华丝国际股份有限公司 | Sulfur-containing compounds as solvents |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0840983A (en) * | 1994-08-01 | 1996-02-13 | Mitsubishi Chem Corp | Production of lactic acid ester |
| CN101511769A (en) * | 2006-07-06 | 2009-08-19 | 斯蒂潘公司 | Alkyl lactyllactates and processes of making the same |
| CN102675102A (en) * | 2012-04-27 | 2012-09-19 | 孝感市易生新材料有限公司 | Continuous production method of high-content high-optical-purity lactate |
-
2014
- 2014-04-22 CN CN201410165748.7A patent/CN103922933A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0840983A (en) * | 1994-08-01 | 1996-02-13 | Mitsubishi Chem Corp | Production of lactic acid ester |
| CN101511769A (en) * | 2006-07-06 | 2009-08-19 | 斯蒂潘公司 | Alkyl lactyllactates and processes of making the same |
| CN102675102A (en) * | 2012-04-27 | 2012-09-19 | 孝感市易生新材料有限公司 | Continuous production method of high-content high-optical-purity lactate |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104803844A (en) * | 2015-03-27 | 2015-07-29 | 中国科学院长春应用化学研究所 | Method for preparing lactate from waste containing polylactic acid chain segments |
| CN105061201A (en) * | 2015-07-31 | 2015-11-18 | 福建农林大学 | Preparation method of lactic ester |
| CN112707851A (en) * | 2015-11-12 | 2021-04-27 | 诺华丝国际股份有限公司 | Sulfur-containing compounds as solvents |
| CN112552168A (en) * | 2020-12-16 | 2021-03-26 | 盐城市春竹香料有限公司 | Process method for preparing ethyl lactate by rectification |
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Application publication date: 20140716 |