CN104628563A - Synthetic process for preparing lactate from lactic acid - Google Patents
Synthetic process for preparing lactate from lactic acid Download PDFInfo
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- C07—ORGANIC CHEMISTRY
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- C07C67/00—Preparation of carboxylic acid esters
- C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
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- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
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Abstract
The invention relates to an improved synthetic process for preparing lactate from lactic acid. The synthetic process is characterized in that polylactic acid is directly prepared from lactic acids of different concentrations by virtue of a water separating agent through azeotropic dehydration, after the water separating agent is recycled by virtue of reduced pressure distillation, alcohol with 2-7 times of molar weights of lactic acids is added and is heated at 100-130 DEG, and transesterification is carried out, so as to synthesize corresponding lactate. According to the synthetic process, water produced in a reaction system can be efficiently and rapidly removed, the increase of lactate conversion rate is promoted, the esterification rate of the process can reach above 98%, and the chemical purity of the product can reach above 99.5%.
Description
Technical field
The invention belongs to field of chemical technology, be specifically related to the improvement synthesis technique that lactic acid prepares lactate, this technique well can solve efficient fast dewatering in lactate building-up process, reduce the problem of product or significant loss, and then reaches the object improving feed stock conversion and product yield.
Background technology
Lactate mostly is colourless volatile liquid, often has sweet fruital smell, is often applied to in the food flavour of modulation Rum, milk, cream, grape wine, fruit wine etc. and wine perfume formulation; Simultaneously lactate low toxicity and there is biodegradable, have Development volue and application prospect " green solvent ", people are usually made the environmentally friendly solvent of the products such as cold coating, tackiness agent, ink, be used as lubricant in pharmaceutical industry, electron trade is used as clean-out system, have purposes prospect very widely in the industry.In addition, the chirality L obtained by the lactic acid of natural chiral or D-ALPHA-Hydroxypropionic acid ester can be used as chiral synthesize raw material, stereotaxis synthesizes various Chiral pesticide (as metalaxyl-M (the R isomer of metaxanin), quizalofopPethyl and fragrant oxygen phenoxy propionic acid weedicide etc.) and chiral drug (as glutamine dipeptide etc.), has important value to raising product drug effect.
Lactate synthesis report is a lot, and has their own characteristics each, and is that the main production synthetic method of starting raw material can sum up three major types below with lactic acid:
One, take lactic acid as raw material direct esterification synthesis method, this synthetic method is that material acid and alcohol carry out the obtained target product lactate of direct esterification reaction under an acidic catalyst condition, the method is the main method that current traditional industry is produced, correlative study report is too many, main research in the recent period concentrates on catalyzer improvement aspect, bibliographical information a large amount of new catalyst is as super acids resin, solid-carrying heteropolyacid, modified molecular screen, Zeo-karb, acidic ion liquid, metal oxide or muriate etc., the an acidic catalyst that the classics of summary document are common has the vitriol oil [agricultural chemicals, 2001, 40 (8): 17, Chinese Journal of Pharmaceuticals, 1984, (02): 37 ~ 39, Kongop Hwahak, 2005,16 (2): 243 ~ 249, Biomacromolecules, 2010,11 (8): 2008-2015, print during chemical industry, 2002,16 (4): 48 ~ 49, CN200910016867.5 (2009), CN200810239459.1 (2008)], tosic acid [Journal of the American Chemical Society, 1962,84:1940, Journal of the Chemical Society [Section] C:Organic, 1971, (13): 2432 ~ 40], FeCl3 [prints during chemical industry, 1999, (4): 7 ~ 12, CN200710020367.X (2007)], boric acid [Organic Letters, 2004, 6 (5), 679 ~ 681], various hydrosulfate [synthetic chemistry, 2001:9 (4): 375 ~ 37, CN201310059696. (2013)], SOCl2 [Journal of Organic Chemistry, 1987,52 (22): 4978, Journal of the American ChemicalSociety, 2004,126 (35): 10992-11008], HCl [Organic & Biomolecular Chemistry, 2005,3 (20): 3749 ~ 3756], Fe2 (SO4) 3-H2SO4 [Journal of Chemical Research, 2004, (3): 226 ~ 227], strong-acid ion exchange resin [fine-chemical intermediate, 2007,37(4): 2223, chemical industry in Jiangsu Province, 2007,35(5): 37 ~ 39, Henan chemical industry, 2004,11:12 ~ 14, U.S. 20060014977 (2006), KR2012009879 (2012), 3rd National Chemical engineering and biochemical industry annual meeting and first Guangxi chemical postgraduate academic marketplace, 2006,268 ~ 273], NaH2PO4/SiO2 solid acid catalyst [Industrial Catalysis, 2009,17 (90): 12 ~ 16], various solid super acid catalyst [chemical research and application, 2004,16 (4): 505-506, chemical intermediate, 2012, (7): 50 ~ 52] and acidic ionic liquid [CN 200810046258.X(2008), CN 201010211280.2 (2010), WO 2014125020 (2014)] etc., in addition, take lactic acid as the synthesis method also having a kind of lactic acid autocatalysis concept in the synthesis method of raw material, namely react and directly carry out under the condition not adding catalyzer, its representative document has CN200980128567.4(2009), BE1017951A3 (2008) and IN2001DE00078(2001) etc.
This method except catalyzer in its lactate synthesis technique dewatering also very important; majority method adopts point aqua (as hexanaphthene, benzene, toluene etc.) or self alcohol azeotropic point water law householder method to promote that [CN200410057324.5 (2004), CN200380104917.6 (2003) are carried out in reaction smoothly; CN200380104918.0 (2003); Hebei College of Science and Engineering's journal, 2001,23 (4): 55 ~ 57; Jiangxi chemical industry, 2000,17 (12): 714 ~ 716], but during azeotropic water removing, often product lactate also can be taken out of, and particularly azeotropic water removing method poor effect during methyl lactate synthesis, affects productive rate and improves; Also occurred that use permeable membrane was except water law is to realize dewatering process [Chemical Engineering Journal, 2010,165 (2): 693 ~ 700 in recent years; CN200710020367.X(2007)], but this method permeable membrane price is high, and often needs pressurization or decompression for making water be separated from system smoothly, and this will affect the permselective property of film, increase technique controlling difficulty.
Two, lactic acid prepares rac-Lactide synthesis method, Chinese patent CN201010262384.6(2010), CN201010261242.8(2010) and CN201210128250.4(2012) report and use the refined lactide prepared by lactic acid to be the method for Material synthesis lactate, the method great advantage is the high-optical-purity that can be ensured lactate by the polishing purification of chirality rac-Lactide, because transesterify system is anhydrous, conversion rate of esterification is high, but disadvantage is rac-Lactide prepares that productive rate is low, temperature of reaction and cleansing temp all compared with high, energy consumption is large.
Three, take lactic acid salt as Material synthesis method; the sodium of lactic acid or calcium salt reacting by heating in the High Temperature High Pressure system of methyl alcohol and carbonic acid gas directly can generate methyl lactate [Industrial & Engineering Chemistry Research; 2012,51 (4): 1498 ~ 1505; WO2011027211 (2011)]; Another US Patent No. 20120142945(2012), CN200910068835(2009), CN94101298(1994) etc. report the lactic acid ammonium salt using fermenation raw liquid ammonification to obtain react with alcohol the synthetic method preparing lactate under an acidic catalyst such as sulfuric acid or biological enzyme condition.This method is mainly used in lower concentration lactic acid fermentation liquid and produces ester by esterification, and then product ester and lactic acid and water, alcohol azeotropic are taken out of, reach high efficiency separation lactic acid object, therefore the productive rate of product ester and purity are all not high.
The document synthetic method that above-mentioned lactic acid prepares lactate differs from one another, also there are respective relative merits, but obviously can find out that its esterification dehydration is also very important except catalyst choice in the factor of the lactated productive rate of impact, seek a kind of efficient, simple and direct, good method of sloughing water in esterification system fast, will be conducive to significantly improving synthetic yield.
Summary of the invention
The object of this invention is to provide a kind of new lactic acid to prepare lactate and improve synthesis technique, this technique can efficient fast dewatering, and reduce product or significant loss, technological process is simple, and energy high yield, high purity obtain target product lactate.
The present invention synthesizes imagination, and to derive from lactic acid be bifunctional structure, and the ultimate principle of conventional lactate synthesis is that lactic acid carries out esterification with alcohol and obtains target compound lactate under an acidic catalyst condition, for its reaction equation of methanol esterification is:
In fact this synthesis is the reversible equilibrium system of a relatively complicated polycomponent mixing, this is because lactic acid is bifunctional, also self esterification side reaction be can there is when itself and alcohol esterification and dimer or chain polyester by product generated, also can there is transesterification reaction and produce dimer or chain polyester by product in the product lactate even after esterification, this is also the high but major cause that isolated yield is not high of usual esterification yied as improper in distillation procedure in acid condition.The water produced by theoretical analysis known increase alcohol consumption and timely removing is conducive to the carrying out of esterification, and the increase of alcohol consumption is conducive to reaction and transforms, but not only increases alcohol distillation amount during separation and purification product, and the azeotropy of alcohol and ester also reduces isolated yield; Effective means is compared in dehydration, azeotropic dehydration conventional before this produces the polycomponent azeotropic system of ester, alcohol, water and point aqua often, this will affect productive rate improve and the reaction times longer, use rectifying azeotropic dehydration or azeotropic liquid siccative (as CaO, magnesium sulfate, sodium sulfate and molecular sieve etc.) dryness shrinkage creek or use permeable membrane permeating and dewatering method can head it off, but too increase production process and equipment investment, production cost all can significantly improve simultaneously.When the present invention considers that lactic acid prepares lactate, esterification terminal can be a lactate all the time, alcohol, polyester, the reversible equilibrium system that Determining Micro Acid and water etc. form jointly, and raffinate usually after distillage usually can recovery, alcoholysis improves product yield again, therefore the present invention propose new lactic acid prepare lactate improve synthesis technique, lactate synthesis is divided into two stages by this technique: first lactic acid uses a point aqua azeotropic band water direct esterification to obtain poly(lactic acid) under an acidic catalyst katalysis, this method not only can slough the water between lactic acid molecules fast, and slough the water of esterification generation easily, owing to not producing the lactate of small-molecular-weight in this process, under common point of aqua reflux temperature, lactic acid saturated vapor pressure is not high, thus the azeotropic loss of raw material and product is avoided, guarantee is provided for improving productive rate, secondly, Distillation recovery directly adds alcohol and carries out acid catalyzed transesterify alcoholysis reaction after dividing aqua, the same reversible equilibrium system that can reach lactate, alcohol, polyester, Determining Micro Acid and water etc. and jointly form, this equilibrium system and the equilibrium system that common synthetic method obtains are almost consistent, finally can obtain target product lactate with ordinary method separation and purification.
Synthesis technique specific features of the present invention is: the lactic acid of various concentration directly uses a point aqua azeotropic dehydration to obtain poly(lactic acid) under an acidic catalyst condition, the alcohol heating under pressurization or condition of normal pressure adding 2 ~ 7 times of lactic acid mole numbers after distillation removing point aqua is carried out transesterification reaction and is synthesized corresponding lactate, after conventional processing rectification under vacuum high-purity target product lactate.
Lactic acid of the present invention can be 50 ~ 100%(weight ratio) the commercially available lactic acid of various concentration also can be the raffinate after lactic acid molecules distillation; Its point of aqua can be common benzene, toluene, hexanaphthene or the heptane etc. of esterification.
An acidic catalyst of the present invention can use esterification catalysts, namely can be common various mineral acids, Acidic inorganic salts, super acids resin, solid-carrying heteropolyacid or Zeo-karb, because namely this catalyzer will be used for the preparation of poly(lactic acid), again for poly(lactic acid) alcoholysis synthesizing lactic acid ester, and homogeneous acid catalyst and strongly acidic catalyst are conducive to reaction completes, therefore preferred acidic catalyzer of the present invention is the vitriol oil, tosic acid and sodium pyrosulfate.An acidic catalyst consumption is 0.2 ~ 5.0% of corresponding pure lactic acid quality, and preferable amount is 0.5 ~ 2.0%.
The present invention uses point aqua azeotropic dehydration 1 ~ 4 h.When using a point aqua azeotropic dehydration to obtain poly(lactic acid), intermolecular aqueous solvent can separate by azeotropic fast, continue the water that reflux water-dividing can separate esterification generation, promote the generation of poly(lactic acid), usual 1 ~ 4 h just can reach the almost anhydrous effect continuing to separate, the distilled that now can reduce pressure reclaims a point aqua, final outer bath temperature can reach 110 ~ 130 DEG C, reduced vacuum degree gauge pressure is 0.60 ~ 0.98Mpa, can distillation dehydration further under this condition, improve polylactic acid molecule amount, test result shows that the poly(lactic acid) viscosity-average molecular weight that this method obtains mostly is between 1000 ~ 8000, lactate transformation efficiency difference corresponding within the scope of this is no more than 1.5%, therefore its viscosity-average molecular weight of poly(lactic acid) of preparation is greater than more than 2000 and namely can be used for the next step.
Alcohol of the present invention is the alcohol at different levels of C1 ~ C8, and its consumption is unsuitable too much be 2 ~ 7 times of lactic acid mole number, wherein preferably 2 ~ 4 times.
Poly(lactic acid) of the present invention and alcohol Hybrid Heating carry out transesterification reaction can synthesize corresponding lactate, temperature of reaction is very large to alcoholysis rate, improve temperature of reaction and be conducive to the quickening of alcoholysis speed, usually the ester conversion rate reaction times that normal methanol eddy alcoholysis completes more than 98% needs more than 12h, and temperature of reaction is when reaching 120 DEG C, reaction solution directly uses high resolving power proton magnetic to follow the tracks of reaction, after known 3 h, its poly(lactic acid) transformation efficiency can reach more than 98.6%, but temperature of reaction is also unsuitable too high, after more than 130 DEG C, the side reaction of the etherification reaction of alcohol and the dehydration generation alkene of alcohol and product lactate increases gradually, particularly lactate hydroxyls dehydrate reaction generation acrylate is easily polymerized, this not only directly reduces reaction yield, and the polyacrylic ester generated is at purifying products last stage meeting product wrapping, isolated yield is reduced further, therefore the temperature of reaction that the present invention uses is 80 ~ 150 DEG C, reaction times 1.0 ~ 12.0 h, its preferable reaction temperature is 100 ~ 130 DEG C, reaction times 1.5 ~ 5.0 h.Improve system temperature of reaction for low-boiling point alcohols such as methyl alcohol, ethanol, propyl alcohol by pressuring method, its pressure is low pressure range, is generally 0.15 ~ 0.30Mpa, the low pressure requirements of reaction can not significantly produce in equipment investment.
Product of the present invention is by rectification under vacuum mode purifying, this mode can reduce distillation temperature, be conducive to reducing product ester and exchange polymerization side reactions, improve product separation productive rate, decrease corresponding alcohol simultaneously and produce, increase product purity, products obtained therefrom purity of the present invention can reach more than 99.5%, in addition, its vinasse main component is still poly-lactic acid ester, and this raffinate can be directly used in Alcoholysis Step and reclaim use.
The recovery that the present invention can be used for the lactic acid raffinate after molecular distillation uses, this raffinate main component is lactic acid oligomer and lactic acid, but the unknown organism in the trace amount acid also obtained containing lactic acid high temperature dehydration and polyacrylic acid and fermented liquid, this raffinate uses synthesis technique of the present invention can obtain the ester of various correspondence, reach recovery application target, because raffinate purity is not high, and toughness foreign matter content is high, therefore product separation yield is lower, productive rate is about between 72 ~ 86%, raffinate toughness impurity after esterified prod distillation is simultaneously a lot, be unworthy again reclaiming use, experiment shows as vinasse directly reclaims alcoholysis, isolate product volume only about 5%, reclaim use as raffinate added reaction system, then thickness impurity product wrapping directly affects product separation productive rate, and now isolated yield can drop to 53 ~ 65%.
Characteristic of the present invention and beneficial effect are:
1, compared with preparing lactate synthesis technique with conventional lactic acid, maximum feature of the present invention is the esterification of directly not carrying out lactic acid and alcohol, but utilize lactic acid bifunctional characteristic to carry out self fat polymerization, and use point direct azeotropic of aqua to slough the water of reaction system, carry out transesterify alcoholysis synthesizing lactic acid ester again, this reaction system dewatering type is not only fast efficient, ester is produced when there is not the azeotropic dehydration of ordinary method, alcohol, the polycomponent azeotropic system of water and point aqua, avoid the loss of product ester or alcohol, this will be conducive to the raising of productive rate, and this dewatering type makes synthesis technique of the present invention have wide spectrum suitability, almost be applicable to the lactate synthesis of all alcohol, particularly be applied to its advantage in the methyl lactate synthesis being not suitable for using point water law to prepare more obvious.
2, synthesis technique lactate transformation efficiency of the present invention is very high, can reach more than 98%, even can reach the degree of almost esterification completely, this is that this greatly facilitates esterification and carries out to forward owing to having completed sloughing of water that the aqueous solvent of reaction system and esterification produce early stage.
Lactic acid provided by the invention is prepared lactate and is improved synthesis technique easily-controlled operation, and last handling process is simple, is applicable to scale operation.
Embodiment
The present invention is illustrated further by following unrestriced embodiment, but needs to understand described embodiment only in order to the present invention to be described, and is not used to limit the scope of the invention.
embodiment onethermometer is being housed, profit water trap, industrial weight ratio 80% lactic acid of 28.2 g is added in the three-necked flask of reflux condensing tube, 0.2 mL sulfuric acid and 30 mL hexanaphthenes (or benzene), be placed in magnetic agitation well heater, thermal dehydration under induction stirring, to separating rear stopping heating without the globule, about 1.5 h, separate the water layer in profit water trap, change vacuum distillation apparatus, bath temperature 120 DEG C and reduced vacuum degree gauge pressure are that under 0.60 ~ 0.95Mpa condition, decompression steams a point aqua outside, residual solution dehydration lactic acid is continued to employ, and point aqua reclaims and uses.
The acid of above-mentioned dehydrated milk, 20mL dehydrated alcohol, the 0.25 mL vitriol oil is added successively in the glass tube sealing of 50 mL, outer bath temperature rises to 130 DEG C, back flow reaction 6 h, after being cooled to room temperature, sampling uses the known ester conversion rate of high resolving power proton Magnetic testi about 99.2%, direct vacuum fractionation recycling design and distillage after reaction solution calcium peroxide bed course, collect 54 DEG C/11mmHg cut and obtain 26.6g product, productive rate 90.1%, product chemical purity 99.5%, vinasse reclaims and uses.
embodiment twothermometer is being housed, profit water trap, industrial weight ratio 50% lactic acid of 90.0 g is added in the three-necked flask of reflux condensing tube, 1.2 g tosic acid and 30 mL hexanaphthenes (or benzene), be placed in magnetic agitation well heater, thermal dehydration under induction stirring, to separating rear stopping heating without the globule, about 3 h, separate the water layer in profit water trap, change vacuum distillation apparatus, bath temperature 110 DEG C and reduced vacuum degree gauge pressure are that under 0.90Mpa condition, decompression steams a point aqua outside, residual solution is that dehydration lactic acid is continued to employ, and point aqua reclaims and uses.
In the there-necked flask of 100 mL, add the above-mentioned dehydration lactic acid of 10.0 g, 37.3. g primary isoamyl alcohol, the 0.25 mL vitriol oil successively, be warming up to interior temperature 122 DEG C, reflux 4 h.After being cooled to room temperature, under ice-water bath condition, adding saturated sodium bicarbonate solution, to be neutralized to pH value be 7 ~ 8; Add 40 mL extraction into ethyl acetate layerings except aqueous phase, stay organic phase; The aqueous phase separated adds 10 mL extraction into ethyl acetate again, stays organic phase and together with merging with organic phase above, adds appropriate anhydrous sodium sulphate dried overnight, then suction filtration removing sodium sulfate, reserved filtrate.Under pump vacuum degree is 0.098 Mpa condition, be warmed up to 120 DEG C gradually and carry out vacuum distillation recovered solvent and primary isoamyl alcohol, use oil pump instead and proceed underpressure distillation, namely the cut collecting 65 DEG C/2mmHg obtains product isoamyl lactate 18.5 g, productive rate 83.5%, chemical purity 98.6%, in bottle, residue residual rate 9.3 % is recyclable.
embodiment threethermometer is being housed, profit water trap, 45.0 g weight ratio 100% molecular distillation lactic acid are added in the three-necked flask of reflux condensing tube, 1.0g sodium pyrosulfate and 30 mL toluene, be placed in magnetic agitation well heater, thermal dehydration under induction stirring, to separating rear stopping heating without the globule, about 4 h, separate the water layer in profit water trap, change vacuum distillation apparatus, bath temperature 125 DEG C and reduced vacuum degree gauge pressure are that under 0.96Mpa condition, decompression steams a point aqua outside, residual dehydration lactic acid is continued to employ, and point aqua reclaims and uses.
Add in reaction flask by above-mentioned dehydration lactic acid, 120.0 g butanols, the 1.2 mL vitriol oils, reflux 5 h to be warming up to interior temperature 115 DEG C (oil bath 150 DEG C).After being cooled to room temperature, under ice-water bath condition, adding saturated sodium bicarbonate solution, to be neutralized to pH value be 7 ~ 8; Add 240 mL extraction into ethyl acetate layerings except aqueous phase, stay organic phase; The aqueous phase separated adds 80 mL extraction into ethyl acetate once again, and organic phase merges together, adds appropriate anhydrous sodium sulphate dried overnight, then suction filtration removing sodium sulfate, reserved filtrate.Under vacuum tightness is 0.099 Mpa condition, heat up gradually and carry out vacuum fractionation, recycling design and butanols, namely the cut collecting 80 DEG C obtains product n-butyl lactate, productive rate 87%, chemical purity 99.0%.
embodiment fourthermometer is being housed, profit water trap, in the three-necked flask of reflux condensing tube, is adding industrial weight ratio 80% lactic acid of 1125 g, 10mL sulfuric acid and 500 mL toluene, be placed in magnetic agitation well heater, thermal dehydration under induction stirring, to separating rear stopping heating without the globule, about 3 h, separate the water layer in profit water trap, change vacuum distillation apparatus, bath temperature 120 DEG C and reduced vacuum degree gauge pressure are that under 0.97Mpa condition, decompression steams a point aqua outside, residual dehydration lactic acid is continued to employ, and point aqua reclaims and uses.
1000 mL anhydrous methanols and the 5.0 mL vitriol oils are added to above-mentioned debris, be uniformly mixed, moving to 2L is with in teflon-lined autoclave pressure, back flow reaction 3h under temperature of reaction 120 DEG C of conditions, stopped reaction, leaves standstill, cooling, sampling uses the known ester conversion rate of high resolving power proton Magnetic testi about 98.8%, with appropriate bases neutralization reaction liquid, filters neutralizer directly carries out distillation purifying.
Carry out air distillation to above-mentioned neutralizer after the three-necked flask that thermometer and decompression distillation system are housed installs additional the long fractional column of about 50cm and reclaim methyl alcohol, this methyl alcohol is containing micro-azeotropic product, recyclable.After air distillation, progressively improve distillation system vacuum tightness to gauge pressure 0.05 ~ 0.06MPa, further removing methyl alcohol, product is steamed without vacuum tightness decompression can be promoted during obvious cut further, collect 58 DEG C/0.099MPa cut about 1228 g, productive rate 93.4%, product chemical purity 99.6%, residue is recyclable.
embodiment fivethermometer is being housed, profit water trap, 45.0 g molecular distillation lactic acid raffinates are added in the three-necked flask of reflux condensing tube, 1.0g sodium pyrosulfate-ferric sulfate (1:1) mixture and 30 mL benzene, be placed in magnetic agitation well heater, thermal dehydration under induction stirring, to separating rear stopping heating without the globule, about 3 h, separate the water layer in profit water trap, change vacuum distillation apparatus, bath temperature 125 DEG C and reduced vacuum degree gauge pressure are that under 0.95Mpa condition, decompression steams a point aqua outside, residual dehydration lactic acid is continued to employ, and point aqua reclaims and uses.
Add 40 mL anhydrous methanols and the 1.0 mL vitriol oils to above-mentioned debris, be uniformly mixed, move to 100 mL and be with in teflon-lined autoclave pressure, back flow reaction 3h under temperature of reaction 130 DEG C of conditions, stopped reaction, leaves standstill, cooling, directly vacuum fractionation purified product is carried out after neutralization reaction liquid, collect 54 ~ 58 DEG C/0.099MPa cut about 42.4 g, productive rate 81.6%, product chemical purity 99.0%, residue about 17.3%, this residue can not reclaim use.
Claims (10)
1. a lactic acid prepares the synthesis technique of lactate, it is characterized in that: lactic acid direct use under an acidic catalyst condition divides an aqua azeotropic dehydration to obtain poly(lactic acid), the alcohol adding 2 ~ 7 times of lactic acid mole numbers after underpressure distillation removing point aqua is pressurizeing or is heating the lactate carrying out transesterification reaction and synthesize correspondence under condition of normal pressure.
2. synthesis technique according to claim 1, is characterized in that: described lactic acid be weight percentage 50 ~ 100% commercially available lactic acid or lactic acid molecules distillation after raffinate.
3. synthesis technique according to claim 1, is characterized in that: described point of aqua is benzene, toluene, hexanaphthene or heptane.
4. synthesis technique according to claim 1, it is characterized in that: described an acidic catalyst is mineral acid, Acidic inorganic salts, super acids resin, solid-carrying heteropolyacid or Zeo-karb, and wherein preferred acidic catalyzer is the vitriol oil, tosic acid and sodium pyrosulfate.
5. the synthesis technique according to claim 1 or 4, is characterized in that: an acidic catalyst consumption is 0.2 ~ 5.0% of corresponding pure lactic acid quality.
6. synthesis technique according to claim 5, is characterized in that: an acidic catalyst consumption is 0.2 ~ 2.0% of corresponding pure lactic acid quality.
7. synthesis technique according to claim 1, is characterized in that: use point aqua azeotropic dehydration 1 ~ 4 h, and then bath temperature 110 ~ 130 DEG C, reduced vacuum degree gauge pressure are the distilled recovery point aqua that reduces pressure under 0.60 ~ 0.98Mpa condition outside.
8. synthesis technique according to claim 1, is characterized in that: described alcohol is the alcohol at different levels of C1 ~ C8, and its consumption is 2 ~ 4 times of lactic acid mole number.
9. synthesis technique according to claim 1, is characterized in that: the temperature of reaction that transesterification reaction synthesis is carried out in described heating is 80 ~ 150 DEG C, reaction times 1.0 ~ 12.0 h.
10. the synthesis technique according to claim 1 or 8, is characterized in that: described alcohol is methyl alcohol, ethanol or propyl alcohol, and the pressure of transesterification reaction synthesis is 0.15 ~ 0.30Mpa.
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| CN106045853A (en) * | 2016-07-13 | 2016-10-26 | 盐城华德（郸城）生物工程有限公司 | Esterification technology for lactic acid and isoctyl alcohol |
| CN107376031A (en) * | 2017-08-02 | 2017-11-24 | 北京华信佳音医疗科技发展有限责任公司 | A kind of preparation method of collagen PLA hardened composite |
| KR20180106799A (en) * | 2017-03-15 | 2018-10-01 | 씨제이제일제당 (주) | Method for preparation of alkyl lactate |
| CN109438228A (en) * | 2018-09-28 | 2019-03-08 | 武汉三江航天固德生物科技有限公司 | The energy-saving processing technique and device of ethyl lactate |
| CN111269158A (en) * | 2020-03-11 | 2020-06-12 | 西安玄德医药科技有限公司 | Preparation method of α -hydroxy acid ester compound |
| CN111777508A (en) * | 2020-07-09 | 2020-10-16 | 上海浦景化工技术股份有限公司 | Method for recovering glycollate |
| CN115124421A (en) * | 2022-06-23 | 2022-09-30 | 苏州润亚旭日生物科技有限公司 | Synthetic method of lactate |
| CN115504958A (en) * | 2022-10-20 | 2022-12-23 | 山东寿光巨能金玉米开发有限公司 | Method for joint production of lactide and lactate |
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| KR20180106799A (en) * | 2017-03-15 | 2018-10-01 | 씨제이제일제당 (주) | Method for preparation of alkyl lactate |
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| CN111777508B (en) * | 2020-07-09 | 2024-04-30 | 上海浦景化工技术股份有限公司 | Recovery method of glycolate |
| CN115124421A (en) * | 2022-06-23 | 2022-09-30 | 苏州润亚旭日生物科技有限公司 | Synthetic method of lactate |
| CN115504958A (en) * | 2022-10-20 | 2022-12-23 | 山东寿光巨能金玉米开发有限公司 | Method for joint production of lactide and lactate |
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