CA2179768A1 - Isolation of hydroxy carboxylic acids from aqueous solutions - Google Patents
Isolation of hydroxy carboxylic acids from aqueous solutionsInfo
- Publication number
- CA2179768A1 CA2179768A1 CA 2179768 CA2179768A CA2179768A1 CA 2179768 A1 CA2179768 A1 CA 2179768A1 CA 2179768 CA2179768 CA 2179768 CA 2179768 A CA2179768 A CA 2179768A CA 2179768 A1 CA2179768 A1 CA 2179768A1
- Authority
- CA
- Canada
- Prior art keywords
- hydroxy carboxylic
- carboxylic acids
- acid
- aqueous solutions
- extraction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical class OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 title claims abstract description 30
- 239000007864 aqueous solution Substances 0.000 title claims abstract description 11
- 238000002955 isolation Methods 0.000 title description 3
- 238000000034 method Methods 0.000 claims abstract description 24
- 238000000605 extraction Methods 0.000 claims abstract description 19
- 238000004821 distillation Methods 0.000 claims abstract description 8
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 7
- 125000002768 hydroxyalkyl group Chemical group 0.000 claims abstract description 7
- 125000003710 aryl alkyl group Chemical group 0.000 claims abstract description 6
- 125000003118 aryl group Chemical group 0.000 claims abstract description 6
- 125000000753 cycloalkyl group Chemical group 0.000 claims abstract description 6
- 239000000284 extract Substances 0.000 claims abstract description 6
- 125000004432 carbon atom Chemical group C* 0.000 claims abstract description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 3
- 239000001257 hydrogen Substances 0.000 claims abstract description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims abstract description 3
- 150000003334 secondary amides Chemical class 0.000 claims abstract description 3
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims description 12
- 239000004310 lactic acid Substances 0.000 claims description 6
- 235000014655 lactic acid Nutrition 0.000 claims description 6
- 238000000855 fermentation Methods 0.000 claims description 3
- 230000004151 fermentation Effects 0.000 claims description 3
- NZMAJUHVSZBJHL-UHFFFAOYSA-N n,n-dibutylformamide Chemical compound CCCCN(C=O)CCCC NZMAJUHVSZBJHL-UHFFFAOYSA-N 0.000 claims description 3
- 150000002763 monocarboxylic acids Chemical class 0.000 claims 1
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 150000001408 amides Chemical class 0.000 description 9
- 238000005192 partition Methods 0.000 description 7
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 6
- 239000002253 acid Substances 0.000 description 5
- 235000015165 citric acid Nutrition 0.000 description 5
- 150000003254 radicals Chemical class 0.000 description 5
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- 150000001735 carboxylic acids Chemical class 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 description 2
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- RGHNJXZEOKUKBD-SQOUGZDYSA-N D-gluconic acid Chemical compound OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C(O)=O RGHNJXZEOKUKBD-SQOUGZDYSA-N 0.000 description 2
- AEMRFAOFKBGASW-UHFFFAOYSA-N Glycolic acid Chemical compound OCC(O)=O AEMRFAOFKBGASW-UHFFFAOYSA-N 0.000 description 2
- -1 N,N-Dibutylformamide Lactic acid Chemical compound 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- OJGMBLNIHDZDGS-UHFFFAOYSA-N N-Ethylaniline Chemical compound CCNC1=CC=CC=C1 OJGMBLNIHDZDGS-UHFFFAOYSA-N 0.000 description 2
- AFBPFSWMIHJQDM-UHFFFAOYSA-N N-methylaniline Chemical compound CNC1=CC=CC=C1 AFBPFSWMIHJQDM-UHFFFAOYSA-N 0.000 description 2
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 description 2
- 239000008346 aqueous phase Substances 0.000 description 2
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 description 2
- 239000001630 malic acid Substances 0.000 description 2
- 235000011090 malic acid Nutrition 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000012074 organic phase Substances 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- YGSDEFSMJLZEOE-UHFFFAOYSA-N salicylic acid Chemical compound OC(=O)C1=CC=CC=C1O YGSDEFSMJLZEOE-UHFFFAOYSA-N 0.000 description 2
- 150000003335 secondary amines Chemical class 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 150000003512 tertiary amines Chemical class 0.000 description 2
- 238000007056 transamidation reaction Methods 0.000 description 2
- MTCFGRXMJLQNBG-REOHCLBHSA-N (2S)-2-Amino-3-hydroxypropansäure Chemical compound OC[C@H](N)C(O)=O MTCFGRXMJLQNBG-REOHCLBHSA-N 0.000 description 1
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- RGHNJXZEOKUKBD-UHFFFAOYSA-N D-gluconic acid Natural products OCC(O)C(O)C(O)C(O)C(O)=O RGHNJXZEOKUKBD-UHFFFAOYSA-N 0.000 description 1
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 1
- XBPCUCUWBYBCDP-UHFFFAOYSA-N Dicyclohexylamine Chemical compound C1CCCCC1NC1CCCCC1 XBPCUCUWBYBCDP-UHFFFAOYSA-N 0.000 description 1
- AYFVYJQAPQTCCC-GBXIJSLDSA-N L-threonine Chemical compound C[C@@H](O)[C@H](N)C(O)=O AYFVYJQAPQTCCC-GBXIJSLDSA-N 0.000 description 1
- OUYCCCASQSFEME-QMMMGPOBSA-N L-tyrosine Chemical compound OC(=O)[C@@H](N)CC1=CC=C(O)C=C1 OUYCCCASQSFEME-QMMMGPOBSA-N 0.000 description 1
- VCUFZILGIRCDQQ-KRWDZBQOSA-N N-[[(5S)-2-oxo-3-(2-oxo-3H-1,3-benzoxazol-6-yl)-1,3-oxazolidin-5-yl]methyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C1O[C@H](CN1C1=CC2=C(NC(O2)=O)C=C1)CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F VCUFZILGIRCDQQ-KRWDZBQOSA-N 0.000 description 1
- XTUVJUMINZSXGF-UHFFFAOYSA-N N-methylcyclohexylamine Chemical compound CNC1CCCCC1 XTUVJUMINZSXGF-UHFFFAOYSA-N 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- MTCFGRXMJLQNBG-UHFFFAOYSA-N Serine Natural products OCC(N)C(O)=O MTCFGRXMJLQNBG-UHFFFAOYSA-N 0.000 description 1
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 1
- AYFVYJQAPQTCCC-UHFFFAOYSA-N Threonine Natural products CC(O)C(N)C(O)=O AYFVYJQAPQTCCC-UHFFFAOYSA-N 0.000 description 1
- 239000004473 Threonine Substances 0.000 description 1
- 235000011054 acetic acid Nutrition 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- JZOWELQSRSLFSD-UHFFFAOYSA-N benzene;2-hydroxypropanoic acid Chemical compound CC(O)C(O)=O.C1=CC=CC=C1 JZOWELQSRSLFSD-UHFFFAOYSA-N 0.000 description 1
- 235000010633 broth Nutrition 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- WZHCOOQXZCIUNC-UHFFFAOYSA-N cyclandelate Chemical compound C1C(C)(C)CC(C)CC1OC(=O)C(O)C1=CC=CC=C1 WZHCOOQXZCIUNC-UHFFFAOYSA-N 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- JQVDAXLFBXTEQA-UHFFFAOYSA-N dibutylamine Chemical compound CCCCNCCCC JQVDAXLFBXTEQA-UHFFFAOYSA-N 0.000 description 1
- 230000002255 enzymatic effect Effects 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 125000002485 formyl group Chemical group [H]C(*)=O 0.000 description 1
- 238000005194 fractionation Methods 0.000 description 1
- 239000000174 gluconic acid Substances 0.000 description 1
- 235000012208 gluconic acid Nutrition 0.000 description 1
- ZXORIQDKFRZFHV-UHFFFAOYSA-N n,n-dibutyl-2-hydroxypropanamide Chemical compound CCCCN(C(=O)C(C)O)CCCC ZXORIQDKFRZFHV-UHFFFAOYSA-N 0.000 description 1
- XAROAZKXMDRYAF-UHFFFAOYSA-N n,n-dibutylpropanamide Chemical compound CCCCN(C(=O)CC)CCCC XAROAZKXMDRYAF-UHFFFAOYSA-N 0.000 description 1
- ARCMPHHHUFVAOI-UHFFFAOYSA-N n,n-dipropylpropanamide Chemical compound CCCN(CCC)C(=O)CC ARCMPHHHUFVAOI-UHFFFAOYSA-N 0.000 description 1
- VXXLEXCQCSPKFI-UHFFFAOYSA-N n-butylcyclohexanamine Chemical compound CCCCNC1CCCCC1 VXXLEXCQCSPKFI-UHFFFAOYSA-N 0.000 description 1
- AGVKXDPPPSLISR-UHFFFAOYSA-N n-ethylcyclohexanamine Chemical compound CCNC1CCCCC1 AGVKXDPPPSLISR-UHFFFAOYSA-N 0.000 description 1
- RIWRFSMVIUAEBX-UHFFFAOYSA-N n-methyl-1-phenylmethanamine Chemical compound CNCC1=CC=CC=C1 RIWRFSMVIUAEBX-UHFFFAOYSA-N 0.000 description 1
- BGWFQRDYRSCOCO-UHFFFAOYSA-N n-methylheptan-2-amine Chemical compound CCCCCC(C)NC BGWFQRDYRSCOCO-UHFFFAOYSA-N 0.000 description 1
- JACMPVXHEARCBO-UHFFFAOYSA-N n-pentylpentan-1-amine Chemical compound CCCCCNCCCCC JACMPVXHEARCBO-UHFFFAOYSA-N 0.000 description 1
- PXKCSKRXWAZGFK-UHFFFAOYSA-N n-propylcyclohexanamine Chemical compound CCCNC1CCCCC1 PXKCSKRXWAZGFK-UHFFFAOYSA-N 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- FJKROLUGYXJWQN-UHFFFAOYSA-N papa-hydroxy-benzoic acid Natural products OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 235000019260 propionic acid Nutrition 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 description 1
- 230000006340 racemization Effects 0.000 description 1
- 238000009666 routine test Methods 0.000 description 1
- 229960004889 salicylic acid Drugs 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000011975 tartaric acid Substances 0.000 description 1
- 235000002906 tartaric acid Nutrition 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- OUYCCCASQSFEME-UHFFFAOYSA-N tyrosine Natural products OC(=O)C(N)CC1=CC=C(O)C=C1 OUYCCCASQSFEME-UHFFFAOYSA-N 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 238000010626 work up procedure Methods 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/48—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The present invention relates to a process for isolating hydroxy carboxylic acids by extraction from their dilute aqueous solutions and subsequent distillation of the extracts obtained in this way, wherein the extractant used is a secondary amide of the general formula I
I
where R1 is hydrogen, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups and R2 and R3 are, independently of one another, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups, with the proviso that the total of the carbon atoms in R1, R2 and R3 is from 7 to 14.
I
where R1 is hydrogen, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups and R2 and R3 are, independently of one another, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups, with the proviso that the total of the carbon atoms in R1, R2 and R3 is from 7 to 14.
Description
- 217976~
The isolation of hydroxy carboxylic acids from aqueous solutions The present invention relates to a novel process for isolating hydroxy carboxylic acids from their aqueous solutions.
Besides chemical syntheses, hydroxy carboxylic acids are frequently also prepared by enzymatic processes. In this case, the hydroxy carboxylic acids result in the form of dilute aqueous 10 solutions in the fermentation medium. A series of elaborate enrichment processes is necessary in order to obtain the hydroxy carboxylic acids, most of which have excellent solubility in water, therefrom in pure or concentrated form.
It is not usually worthwhile to remove the water by direct distillation or using a water-insoluble entrainer because of the high energy input costs.
Because the hydroxy carboxylic acids have high solubility in 20 water, extraction with conventional solvents such as ethyl acetate, methylene chloride or butanol is not particularly efficient, and satisfactory results can be obtained only with elaborate multiple extractions.
To solve this problem, reactive extractions have been proposed;
in these, water-insoluble higher secondary or tertiary amines have been added to the organic extractor, and these form with the hydroxy carboxylic acids the corresponding ammonium salts whose extractability is better.
Chem. Ing.-Techn. 58 (1986) 308-317 describes the possibility of increasing the partition coefficient of salicylic acid in the xylene/water system by a factor of 50 by adding a secondary amine (LA-2).
Chem. Ing.-Techn. 63 (1991) 809-816 refers, for example, to the reactive extraction of lactic acid using the tertiary amine Alamin 336 (tri-n-(C8-C10)-amine).
40 However, the subsequent workup of the extract is industrially difficult because separation of hydroxy carboxylic acids and amines by distillation even under reduced pressure requires relatively high temperatures at which the hydroxy carboxylic acids decompose or undergo unwanted side reactions.
~ 2179768 In the case of enantiomerically pure hydroxy carboxylic acids under these conditions there is often partial racemization of the product, which sets limits on the application of this process.
DE 25 45 658 discloses that the carboxylic acids formic acid, acetic acid, propionic acid and acrylic acid can be extracted from their aqueous solutions satisfactorily with amides. However, there is no reference in this document to whether this process can also be used for carboxylic acids other than the four 10 indicated above.
It is an object of the present invention to provide a process for isolating hydroxy carboxylic acids from their dilute aqueous solutions which does not have the disadvantages described above.
We have found that this object is achieved by isolating hydroxy carboxylic acids by extraction from their dilute aqueous solutions and subsequent distillation of the extracts obtained in this way when the extractant used is a secondary amide of the 20 general formula I
Rl C ~ R2 N ~
where Rl is hydrogen, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups and R2 and R3 are, independently of one another, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups, 30 with the proviso that the total of the carbon atoms in Rl, R2 and R3 is from 7 to 14.
Hydroxy carboxylic acids mean those organic acids which, besides one or more suitable COOH groups, contain at least one hydroxyl group. The process according to the invention can be applied, for example, to mono-, di-, tri- and polyhydroxy carboxylic acids.
The process is particularly suitable for naturally occurring hydroxy carboxylic acids such as glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, mandelic 40 acid, serine, threonine and tyrosine.
The process is very particularly suitable for isolating lactic acid, in particular also enantiomerically pure lactic acid.
Concerning the radicals R2 and.R3 in the amides I, particularly suitable compounds or mixtures thereof are derived from N-ethyl-N-cyclohexylamine, N,N-dicyclohexylamine, N,N-dibutylamine, 21797~8 _ N-methyl-N-benzylamine, N-methylaniline, N-ethylaniline, N,N-diamylamine, N-methyl-N-cyclohexylamine, N-n-butyl-N-cyclo-hexylamine, N-methyl-N-2-heptylamine or N-propyl-N-cyclohexyl-amine.
Concerning the radical Rl, formyl and lower alkyl or hydroxyalkyl groups are preferred.
Since it is sometimes possible for transamidation of the amide I
10 with the hydroxy carboxylic acid to occur, it may be advantagéous to choose as radical Rl in the amide the same radical as the hydroxy carboxylic acid 80 that any transamidation occurring has no adverse effect on the product.
Amides I which are preferably used are those in which the total number of carbon atoms in the radicals Rl, R2 and R3 is less than or equal to 10.
The amides of the formula I either are known or can easily be 20 obtained by known methods. As a rule, the amides I are used without other solvents because the effectiveness of the extraction is maximized in this way. If, however, an extraction is to be carried out at relatively low temperature, ie. below the solidification point of the amide I, it is advisable to add an organic solvent which brings about a reduction in the solidification point.
A measure of the suitability of the extractants is the partition coefficient, which indicates the concentration of the hydroxy 30 carboxylic acid in the extractant in relation to the concentration of the hydroxy carboxylic acid in water.
The complexity of the apparatu~ needed for the extraction increases as this value decreases.
The partition coefficient for water is not so crucial in the process according to the invention because the water dissolved in the extract can easily be removed, together with the extractant, from the hydroxy carboxylic acid by distillation.
The amount of extractant required depends on various parameters, including the temperature, the amount and concentration of the hydroxy carboxylic acid, the number of separation stages and other characteristics of the apparatus and is familiar to the skilled worker or can easily be determined by him.
A temperature range from 0C to 100C is suitable and preferred for the extraction. Although the uptake capacity of the extractant for the hydroxy carboxylic acid is greater at the lower values in this range than at higher temperatures, on the other hand the rate of phase separation is slower. The economic optimum is, as a rule, at from 40C to 80C, and it can easily be determined by a number of routine tests.
The fact that the partition coefficients are distinctly lower at 10 higher temperature than at low temperatures can be additionally exploited by carrying out a temperature-change extraction.
This entails extracting the aqueous hydroxy carboxylic acid solution with amide I at low temperature, eg. 20C to 40C, and subjecting the extract phase to a back-extraction with water at high temperature, eg. 60C to 80C.
The extraction can be carried out continuously or batchwise. In industrial application, continuous extraction by the 20 countercurrent process is preferred.
It is possible if required further to increase the effectiveness by using multistage extraction apparatus, for example batteries of mixers and separators or packed columns, which are familiar in principle to the skilled worker.
The essential feature of the present invention is not the extraction technique, which is conventional, but is the nature of the extractant.
After the extraction step, the extracted phase is separated in a manner familiar to the skilled worker into hydroxy carboxylic acid and extractant and, where appropriate, water by distillation. The result of the overall process is the hydroxy carboxylic acid in pure form or, alternatively, as concentrated solution.
The process according to the invention can be applied to the isolation of hydroxy carboxylic acids which have been prepared 40 chemically or biotechnologically and are in the form of aqueous solutions. It is also suitable furthermore for waste water purification if the aim is to remove hydroxy carboxylic acid. It is particularly suitable for isolating hydroxy carboxylic acid from fermentation broths.
The process according to the invention makes considerable savings possible in energy and capital costs, both by comparison with other extraction processes and by comparison with fractionation by distillation.
The following examples serve to illustrate the invention further.
Example 1 10 Since the suitability of the extractants depends essentially on the partition coefficients Concentration of the acid in the organic phase K =
Concentration of the acid in the aqueous phase this coefficient was determined as follows:
50 g of a 7 ~ strength aqueous solution of the appropriate hydroxy carboxylic acid were stirred with 50 g of extractant at 20 40C until equilibrium was reached. The stirrer was then switched off and the mixture was left until the organic and aqueous phases had clearly separated.
The partition coefficient was formed from the acid concentration which was determined by titration.
The following table summarizes the partition coefficients of some extractants according to the invention and compares them with conventional ones:
21797fi8 Extractant Acid K at 40C
N,N-Dibutylformamide Lactic acid 1.37 " Malic acid 1.36 " Citric acid 2.07 N,N-Dibutylacetamide Lactic acid 1.52 N,N-Dipropylpropionamide ~ 1.23 N,N-Dibutylpropionamide " 1.00 N,N-Di-n-butyllactamide ~ 0.65 Conventional extractants Benzene Lactic acid ~ 0.01 Ethyl acetate " 0.29 Chloroform " 0.01 i-Butanol " 0.84 i-Butanol Citric acid 0.52 20 Example 2 This example shows the temperature dependence of the K value for lactic acid in the N,N-di-n-butylformamide/water system.
The procedure for determining the K value was as indicated in Example 1.
Temperature in C R value 1.37 1.24 1.15 Example 3 This example shows the concentration dependence of the K value of citric acid at 40C in the N,N-di-n-butylformamide/water system.
40 The procedure for determining the X value was as indicated in Example 1.
Equilibrium concentration of K Yalue citric acid in water at 40C
in percent by weight 0.5 2.70 1.1 2.47 2.5 2.07
The isolation of hydroxy carboxylic acids from aqueous solutions The present invention relates to a novel process for isolating hydroxy carboxylic acids from their aqueous solutions.
Besides chemical syntheses, hydroxy carboxylic acids are frequently also prepared by enzymatic processes. In this case, the hydroxy carboxylic acids result in the form of dilute aqueous 10 solutions in the fermentation medium. A series of elaborate enrichment processes is necessary in order to obtain the hydroxy carboxylic acids, most of which have excellent solubility in water, therefrom in pure or concentrated form.
It is not usually worthwhile to remove the water by direct distillation or using a water-insoluble entrainer because of the high energy input costs.
Because the hydroxy carboxylic acids have high solubility in 20 water, extraction with conventional solvents such as ethyl acetate, methylene chloride or butanol is not particularly efficient, and satisfactory results can be obtained only with elaborate multiple extractions.
To solve this problem, reactive extractions have been proposed;
in these, water-insoluble higher secondary or tertiary amines have been added to the organic extractor, and these form with the hydroxy carboxylic acids the corresponding ammonium salts whose extractability is better.
Chem. Ing.-Techn. 58 (1986) 308-317 describes the possibility of increasing the partition coefficient of salicylic acid in the xylene/water system by a factor of 50 by adding a secondary amine (LA-2).
Chem. Ing.-Techn. 63 (1991) 809-816 refers, for example, to the reactive extraction of lactic acid using the tertiary amine Alamin 336 (tri-n-(C8-C10)-amine).
40 However, the subsequent workup of the extract is industrially difficult because separation of hydroxy carboxylic acids and amines by distillation even under reduced pressure requires relatively high temperatures at which the hydroxy carboxylic acids decompose or undergo unwanted side reactions.
~ 2179768 In the case of enantiomerically pure hydroxy carboxylic acids under these conditions there is often partial racemization of the product, which sets limits on the application of this process.
DE 25 45 658 discloses that the carboxylic acids formic acid, acetic acid, propionic acid and acrylic acid can be extracted from their aqueous solutions satisfactorily with amides. However, there is no reference in this document to whether this process can also be used for carboxylic acids other than the four 10 indicated above.
It is an object of the present invention to provide a process for isolating hydroxy carboxylic acids from their dilute aqueous solutions which does not have the disadvantages described above.
We have found that this object is achieved by isolating hydroxy carboxylic acids by extraction from their dilute aqueous solutions and subsequent distillation of the extracts obtained in this way when the extractant used is a secondary amide of the 20 general formula I
Rl C ~ R2 N ~
where Rl is hydrogen, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups and R2 and R3 are, independently of one another, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups, 30 with the proviso that the total of the carbon atoms in Rl, R2 and R3 is from 7 to 14.
Hydroxy carboxylic acids mean those organic acids which, besides one or more suitable COOH groups, contain at least one hydroxyl group. The process according to the invention can be applied, for example, to mono-, di-, tri- and polyhydroxy carboxylic acids.
The process is particularly suitable for naturally occurring hydroxy carboxylic acids such as glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, mandelic 40 acid, serine, threonine and tyrosine.
The process is very particularly suitable for isolating lactic acid, in particular also enantiomerically pure lactic acid.
Concerning the radicals R2 and.R3 in the amides I, particularly suitable compounds or mixtures thereof are derived from N-ethyl-N-cyclohexylamine, N,N-dicyclohexylamine, N,N-dibutylamine, 21797~8 _ N-methyl-N-benzylamine, N-methylaniline, N-ethylaniline, N,N-diamylamine, N-methyl-N-cyclohexylamine, N-n-butyl-N-cyclo-hexylamine, N-methyl-N-2-heptylamine or N-propyl-N-cyclohexyl-amine.
Concerning the radical Rl, formyl and lower alkyl or hydroxyalkyl groups are preferred.
Since it is sometimes possible for transamidation of the amide I
10 with the hydroxy carboxylic acid to occur, it may be advantagéous to choose as radical Rl in the amide the same radical as the hydroxy carboxylic acid 80 that any transamidation occurring has no adverse effect on the product.
Amides I which are preferably used are those in which the total number of carbon atoms in the radicals Rl, R2 and R3 is less than or equal to 10.
The amides of the formula I either are known or can easily be 20 obtained by known methods. As a rule, the amides I are used without other solvents because the effectiveness of the extraction is maximized in this way. If, however, an extraction is to be carried out at relatively low temperature, ie. below the solidification point of the amide I, it is advisable to add an organic solvent which brings about a reduction in the solidification point.
A measure of the suitability of the extractants is the partition coefficient, which indicates the concentration of the hydroxy 30 carboxylic acid in the extractant in relation to the concentration of the hydroxy carboxylic acid in water.
The complexity of the apparatu~ needed for the extraction increases as this value decreases.
The partition coefficient for water is not so crucial in the process according to the invention because the water dissolved in the extract can easily be removed, together with the extractant, from the hydroxy carboxylic acid by distillation.
The amount of extractant required depends on various parameters, including the temperature, the amount and concentration of the hydroxy carboxylic acid, the number of separation stages and other characteristics of the apparatus and is familiar to the skilled worker or can easily be determined by him.
A temperature range from 0C to 100C is suitable and preferred for the extraction. Although the uptake capacity of the extractant for the hydroxy carboxylic acid is greater at the lower values in this range than at higher temperatures, on the other hand the rate of phase separation is slower. The economic optimum is, as a rule, at from 40C to 80C, and it can easily be determined by a number of routine tests.
The fact that the partition coefficients are distinctly lower at 10 higher temperature than at low temperatures can be additionally exploited by carrying out a temperature-change extraction.
This entails extracting the aqueous hydroxy carboxylic acid solution with amide I at low temperature, eg. 20C to 40C, and subjecting the extract phase to a back-extraction with water at high temperature, eg. 60C to 80C.
The extraction can be carried out continuously or batchwise. In industrial application, continuous extraction by the 20 countercurrent process is preferred.
It is possible if required further to increase the effectiveness by using multistage extraction apparatus, for example batteries of mixers and separators or packed columns, which are familiar in principle to the skilled worker.
The essential feature of the present invention is not the extraction technique, which is conventional, but is the nature of the extractant.
After the extraction step, the extracted phase is separated in a manner familiar to the skilled worker into hydroxy carboxylic acid and extractant and, where appropriate, water by distillation. The result of the overall process is the hydroxy carboxylic acid in pure form or, alternatively, as concentrated solution.
The process according to the invention can be applied to the isolation of hydroxy carboxylic acids which have been prepared 40 chemically or biotechnologically and are in the form of aqueous solutions. It is also suitable furthermore for waste water purification if the aim is to remove hydroxy carboxylic acid. It is particularly suitable for isolating hydroxy carboxylic acid from fermentation broths.
The process according to the invention makes considerable savings possible in energy and capital costs, both by comparison with other extraction processes and by comparison with fractionation by distillation.
The following examples serve to illustrate the invention further.
Example 1 10 Since the suitability of the extractants depends essentially on the partition coefficients Concentration of the acid in the organic phase K =
Concentration of the acid in the aqueous phase this coefficient was determined as follows:
50 g of a 7 ~ strength aqueous solution of the appropriate hydroxy carboxylic acid were stirred with 50 g of extractant at 20 40C until equilibrium was reached. The stirrer was then switched off and the mixture was left until the organic and aqueous phases had clearly separated.
The partition coefficient was formed from the acid concentration which was determined by titration.
The following table summarizes the partition coefficients of some extractants according to the invention and compares them with conventional ones:
21797fi8 Extractant Acid K at 40C
N,N-Dibutylformamide Lactic acid 1.37 " Malic acid 1.36 " Citric acid 2.07 N,N-Dibutylacetamide Lactic acid 1.52 N,N-Dipropylpropionamide ~ 1.23 N,N-Dibutylpropionamide " 1.00 N,N-Di-n-butyllactamide ~ 0.65 Conventional extractants Benzene Lactic acid ~ 0.01 Ethyl acetate " 0.29 Chloroform " 0.01 i-Butanol " 0.84 i-Butanol Citric acid 0.52 20 Example 2 This example shows the temperature dependence of the K value for lactic acid in the N,N-di-n-butylformamide/water system.
The procedure for determining the K value was as indicated in Example 1.
Temperature in C R value 1.37 1.24 1.15 Example 3 This example shows the concentration dependence of the K value of citric acid at 40C in the N,N-di-n-butylformamide/water system.
40 The procedure for determining the X value was as indicated in Example 1.
Equilibrium concentration of K Yalue citric acid in water at 40C
in percent by weight 0.5 2.70 1.1 2.47 2.5 2.07
Claims (5)
1. A process for isolating hydroxy carboxylic acids by extraction from their dilute aqueous solutions and subsequent distillation of the extracts obtained in this way, wherein the extractant used is a secondary amide of the general formula I
I
where R1 is hydrogen, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups and R2 and R3 are, independently of one another, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups, with the proviso that the total of the carbon atoms in R1, R2 and R3 is from 7 to 14.
I
where R1 is hydrogen, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups and R2 and R3 are, independently of one another, alkyl, cycloalkyl, aryl, aralkyl or hydroxyalkyl groups, with the proviso that the total of the carbon atoms in R1, R2 and R3 is from 7 to 14.
2. A process as claimed in claim 1, wherein a monohydroxy monocarboxylic acid is extracted.
3. A process as claimed in claim 2, wherein lactic acid is extracted.
4. A process as claimed in claim 1, wherein di-n-butylformamide is used as extractant.
5. A process as claimed in claim 1, wherein the dilute aqueous solution is a fermentation broth.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19522377.2 | 1995-06-22 | ||
| DE1995122377 DE19522377A1 (en) | 1995-06-22 | 1995-06-22 | Process for the production of hydroxycarboxylic acids from aqueous solutions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2179768A1 true CA2179768A1 (en) | 1996-12-23 |
Family
ID=7764791
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2179768 Abandoned CA2179768A1 (en) | 1995-06-22 | 1996-06-21 | Isolation of hydroxy carboxylic acids from aqueous solutions |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0749951A1 (en) |
| JP (1) | JPH0912505A (en) |
| CA (1) | CA2179768A1 (en) |
| DE (1) | DE19522377A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL1013682C2 (en) * | 1999-11-26 | 2001-05-30 | Purac Biochem Bv | Method and device for purifying an aqueous solution of lactic acid. |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2578698A (en) * | 1948-09-24 | 1951-12-18 | Kellogg M W Co | Dehydration of organic acids |
| US4251671A (en) * | 1979-10-05 | 1981-02-17 | Miles Laboratories, Inc. | Extraction of citric acid |
-
1995
- 1995-06-22 DE DE1995122377 patent/DE19522377A1/en not_active Withdrawn
-
1996
- 1996-06-13 EP EP96109505A patent/EP0749951A1/en not_active Withdrawn
- 1996-06-21 CA CA 2179768 patent/CA2179768A1/en not_active Abandoned
- 1996-06-24 JP JP16326396A patent/JPH0912505A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0912505A (en) | 1997-01-14 |
| DE19522377A1 (en) | 1997-01-02 |
| EP0749951A1 (en) | 1996-12-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4275234A (en) | Recovery of acids from aqueous solutions | |
| US4076948A (en) | Process for treatment of adipic acid mother liquor | |
| US9126917B2 (en) | Method for purifying vanillin by liquid-liquid extraction | |
| US4353784A (en) | Method of recovery of acetic acid | |
| EP0711269A4 (en) | ||
| CA1065889A (en) | Isolation of carboxylic acids from their aqueous solutions | |
| EP1385593A1 (en) | Process for obtaining an organic acid from an organic acid ammonium salt, an organic acid amide, or an alkylamine organic acid complex | |
| EP1654212A1 (en) | Process for separating and recovering 3-hydroxypropionic acid and acrylic acid | |
| US6140536A (en) | Process for obtaining 2-hydroxy-4-methylthiobutyric acid (MHA) | |
| KR20040086369A (en) | Method for extracting a macrolide from biomatter | |
| CA2179768A1 (en) | Isolation of hydroxy carboxylic acids from aqueous solutions | |
| US4551208A (en) | Recovery of formic acid by distillation | |
| EP1646597A2 (en) | Process for separating and recovering 3-hydroxypropionic acid and acrylic acid | |
| US5189216A (en) | Isolation of a carboxylic acid from an aqueous solution thereof | |
| US4231994A (en) | Separation of zirconium from hafnium by solvent extraction | |
| KR960006664B1 (en) | Process for the extractive separation of a carboxylic acid from an aqueous solution of the said acid | |
| DE69614108D1 (en) | METHOD FOR OBTAINING ASCORBIC ACID | |
| CN114315603B (en) | Extraction method of 1, 5-pentanediamine and 1, 5-pentanediamine product obtained by extraction method | |
| US4339596A (en) | Treatment of byproduct stream from adipic acid manufacture | |
| CN110914239A (en) | Method for preparing levetiracetam | |
| JPS61176552A (en) | Method for extracting fatty acid | |
| US2876259A (en) | Process for the purification of alkylamino propionate salts | |
| EP0274135B1 (en) | Method for the separation of leucine | |
| US3840593A (en) | Separation of 2,4,5-t and 2,3,7,8-tetrachlorodibenzo-p-dioxin from 2-(2,4,5-trichlorophenoxy)propionic acid contaminated therewith | |
| US6172242B1 (en) | Process for the production of erythorbic acid |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |