CA1065889A - Isolation of carboxylic acids from their aqueous solutions - Google Patents
Isolation of carboxylic acids from their aqueous solutionsInfo
- Publication number
- CA1065889A CA1065889A CA262,961A CA262961A CA1065889A CA 1065889 A CA1065889 A CA 1065889A CA 262961 A CA262961 A CA 262961A CA 1065889 A CA1065889 A CA 1065889A
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- Canada
- Prior art keywords
- acid
- extractant
- aqueous solutions
- carboxylic acids
- radicals
- 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.)
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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
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- 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)
- Extraction Or Liquid Replacement (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE: Carboxylic acids of the ge-neral formula I
where R1 is hydrogen, methyl, ethyl or vinyl, are isolated from their dilute aqueous solutions by extraction followed by distillation of the mixtures obtained, the extractant used being a secondary amide of the general formula II
II
where R2 and R3 are alkyl, cycloalkyl, aryl or aralkyl or con-jointly are 1,4- or 1,5-alkylene, in each case of not more than 8 carbon atoms, with the proviso that the sum of the carbon atoms of R2 and R3 is from 7 to 14 and that only one of these radicals is aryl, and where R4 is one of the radicals R1.
where R1 is hydrogen, methyl, ethyl or vinyl, are isolated from their dilute aqueous solutions by extraction followed by distillation of the mixtures obtained, the extractant used being a secondary amide of the general formula II
II
where R2 and R3 are alkyl, cycloalkyl, aryl or aralkyl or con-jointly are 1,4- or 1,5-alkylene, in each case of not more than 8 carbon atoms, with the proviso that the sum of the carbon atoms of R2 and R3 is from 7 to 14 and that only one of these radicals is aryl, and where R4 is one of the radicals R1.
Description
O.Z. 31,607 ~L06S8~9 ISOLATION OF CARBOXYLIC ACIDS FROM THEIR AQUEOUS SOLUTIONS
. .
The present invention relates to a new process for isolat-ing carboxylic acids of the general formula I
R - COOH
where R1 is hydrogen, methyl, ethyl or vinyl, from their aqueous solutions.
A number of synthe~es result in carboxylic acids I being obtained in the form of their dilute aqueous solutions.
Experience has 9hown th~t if it is desired to isolate the pure or concentrated acids therefrom, substantial technical diffi-culties are encountered. Removal of the water by distillationwhioh in the case of formic acid is in any case not possible at commercially acceptable expense, because of azeotrope forma-tion, re~uires in all other cases both a large amount of energy and expensive distillation columns with numerous trays, since the degree of separation of the acid~water system achieved by a single tray is slight.
6 ~ ~ 8~
O.Z. ~1,607 It is true that the water can be removed more rapidly, and with less expensive equipment, by azeotropic distillation with : :
a water-insoluble liquid such as ethyl acetate or benzene, but this of course requires even more energy than a simple distil-lation For these reasons, numerous separation processes have been developed, which are based on the extraction of the acid with a liquid extractant such as isoamyl acetate or methyl isopropyl ketone.
However, the efficiency of the extractants of the prior art is not fully satisfactory, since the extractants take up insuffi-cient acid and too much water. Hence, mixtures of extractants, acid and water are obtained in every case and these, in turn, require relatively expensiwe further processing since, in the case o~ none of these extractants, the three components can be separated by ~imple distillation.
It is an object of the present invention to increase the e~ficiency of extraction of a carboxylic acid I from its dilute agueous solutions, by providing more suitable extraçtants.
We have found that this object is achieved and that carb-oxylic acids of the general formula I
R1 _ COOH
where R1 is hydrogen, methyl, ethyl or vinyl, can be obtained by extracting their dilute aqueous solutions and then distilling bhe mixtures obtained~ if the extractant used is a secondary amide of the general formula II
R \ O
/ N - C - R II
where R2 and R3 are alkyl, cycloalkyl, aryl or aralkyl or con-joinkly are 1,4- or 1,5-alkylene, in each case of 1 to 8 carbon atoms, with the proviso that the sum of the carbon atoms of R2
. .
The present invention relates to a new process for isolat-ing carboxylic acids of the general formula I
R - COOH
where R1 is hydrogen, methyl, ethyl or vinyl, from their aqueous solutions.
A number of synthe~es result in carboxylic acids I being obtained in the form of their dilute aqueous solutions.
Experience has 9hown th~t if it is desired to isolate the pure or concentrated acids therefrom, substantial technical diffi-culties are encountered. Removal of the water by distillationwhioh in the case of formic acid is in any case not possible at commercially acceptable expense, because of azeotrope forma-tion, re~uires in all other cases both a large amount of energy and expensive distillation columns with numerous trays, since the degree of separation of the acid~water system achieved by a single tray is slight.
6 ~ ~ 8~
O.Z. ~1,607 It is true that the water can be removed more rapidly, and with less expensive equipment, by azeotropic distillation with : :
a water-insoluble liquid such as ethyl acetate or benzene, but this of course requires even more energy than a simple distil-lation For these reasons, numerous separation processes have been developed, which are based on the extraction of the acid with a liquid extractant such as isoamyl acetate or methyl isopropyl ketone.
However, the efficiency of the extractants of the prior art is not fully satisfactory, since the extractants take up insuffi-cient acid and too much water. Hence, mixtures of extractants, acid and water are obtained in every case and these, in turn, require relatively expensiwe further processing since, in the case o~ none of these extractants, the three components can be separated by ~imple distillation.
It is an object of the present invention to increase the e~ficiency of extraction of a carboxylic acid I from its dilute agueous solutions, by providing more suitable extraçtants.
We have found that this object is achieved and that carb-oxylic acids of the general formula I
R1 _ COOH
where R1 is hydrogen, methyl, ethyl or vinyl, can be obtained by extracting their dilute aqueous solutions and then distilling bhe mixtures obtained~ if the extractant used is a secondary amide of the general formula II
R \ O
/ N - C - R II
where R2 and R3 are alkyl, cycloalkyl, aryl or aralkyl or con-joinkly are 1,4- or 1,5-alkylene, in each case of 1 to 8 carbon atoms, with the proviso that the sum of the carbon atoms of R2
- 2 -~ 5~89 o.z. 31,607 and R3 is from 7 to 14 and that only one of these radicals is aryl, and where R4 is one o~ the radicals R1.
Since a trans-amidation with the acid I can take place, extractants where R4 and R1 are identical are always preferred.
Accordingly, formic acid is advantageously extracted with a form-amide, acetic acid with an acetamide, propionic acid with a propion-amide and acrylic acid with an acrylamide II, so that the occurrence of the trans-amidation is outwardly not detectable I~ it is in-tended to isolate mixtures of different acids 3 eO g. formic acid and acetic acidg it is preferred to use the compounds of the form-amide series, as being the most ef~icient compounds of the category which has been defined~
From the point o~ view o~ the amide groupings, particularly suitable compounds II, and their mixtures, are those derived from N-ethyl-N-cyclohexylamine, N,N-dicyclohexylamine, N-methyl-N-benzylamine, N-methylaniline, N-ethylaniline, N,N-diamylamine, N-methyl-N-2~ethylhexylamine, N-n-butyl-N-cyclohexylamine, N-methyl-N 2-heptylamine or N-propyl-N cyclohexylamine. The dibutylform-amides,including above all di-n-bukylformamide, have proved best for rOrmic acid, and N-n-butyl-N-2-ethylhexylacetamide and N-n-butyl-N-cyclohexYlacetamide have proved best for acetic acid.
The amides II are either known compounds or are readily accessible by conventional methods. If their ~reezing point is above the extraction temperature, it is necessary to use mixtures of the extractants II, or to work in the presence of a solvent, preferably an aromatic hydrocarbon such as p-diisopropylbenzene, which does not form an azeotrope with the acids. It is true that in this variant the efficiency of the extractant I~ is reduced, but nevertheless sufficient advantages over conventional methods remain, since the amount of solvent normally required to lower the ~reezing point is low, namely from 10 to 40% by weight, hased on II.
The partition coe~ficient, which is defined in Example 3 and -- 3 ~
~ 65~9 o. z . 31,607 is quoted for several acid/extractant systems is a measure of the suitability of the extractants. The lower is this coefficient, the greater the expense of the equipment required for the extraction~
However, it is not only the partition coeffi~ient for the acid but also the partition coefficient ~or water which has to be taken into account, since, naturally, the isolation of pure or concentrated acid requires less energy if the extractant takes up very little water; this latter condition is fulfilled satisfactorily by all of the extractants of the invention.
The requisite amount of extractant II depends on various para-meters, including, above all, the temperature, the amount and con-centration of acidg the number of separation stages and the other details of the equipment which affect equilibration and hence af~ect the residence time. The amount of extractant II required does not vary fundamentally with the particular extractant used and the particular acid involved.
The preferred temperature range for the extraction is from 0 to 70 C. It is true that at the lower end of this range, the extractant can absorb more acid than at higher temperatures, but on the other hand the rate of equilibration is lower. The economic optimum is in the range of from 20 to l10C.
In the range of fr~m 20 to 40C, from 1 to 10 kg of extractant II are normally required for extracting 1 kg of acid at a contact time Or from 1 to 5 minutes. The amount Or extractant is less ror longer contact times and vice versa. The stated contact times apply to the preferred embodiment of counter-current extraction, in a simple extraction column without other auxiliaries such as ba~les, trays or packing, and under Gonditions where the lighter extractant forms the continuous phase. The efficiency is increased by using multi-stage extraction apparatus, e.g. packed columns or tray columns with, preferably, from 3 to 6 theoretical plates, so that the amount of the extractant can be reduced in accordance with the conventional rules.
~ 4 --5 ~ ~ ~
OOZo 31,607 The above data-~elate to acid concentrations of from 5 to 50% by weight Or the aqueous solution, these being the most commonly encountered concentrations in industry. The depletion ratio, of from 95 to 99% by weight, is relatively constant, i.e.
if the initial solution is of 30% strength, from Oo l to 0O3 of acid remain in the aqueous medium, whilst if a 10% strength solution is extracted, a solution containing from 0005 to 001%
of acid remainsO In general3 it is most economical to take the exkraction to the point that a mixture of the extractant and an acid of from 10 to 40 per cent strength by weight is obtained.
The water is then distilled from this mixture, after which the acid is distilled off in a downstream columnO It is also possible3 using conventional methods, to use an arrangement where only a part of the water is removed in the first column, whilst in the second column the residual water is distilled off together with the acid. In that case, a commercial concentrated acid is obtained instead of the p~re acidO
The above comments relate to the continuous manufacture of carboxylic acids I, which in industry is virtually the only embodiment of importanceJ However, the process can of course also be carried out batchwise, if desired,in which case the general sense of the conditions outlined above must be adhered to.
It should be pointed out that the feature of the process which is essential to the invention is the nature of the ex-tractant, and not the extraction technique used, which is the conventional tec~nique~ To that extent, the condil;ions outlined merelY represent guidelines, from which it is possible to deviate~ in individual cases, in accordance with conventional rules and the conventional process technology, should this be advisable; an example is the treatment of effluent, where the purification of the water is more important than the isolation
Since a trans-amidation with the acid I can take place, extractants where R4 and R1 are identical are always preferred.
Accordingly, formic acid is advantageously extracted with a form-amide, acetic acid with an acetamide, propionic acid with a propion-amide and acrylic acid with an acrylamide II, so that the occurrence of the trans-amidation is outwardly not detectable I~ it is in-tended to isolate mixtures of different acids 3 eO g. formic acid and acetic acidg it is preferred to use the compounds of the form-amide series, as being the most ef~icient compounds of the category which has been defined~
From the point o~ view o~ the amide groupings, particularly suitable compounds II, and their mixtures, are those derived from N-ethyl-N-cyclohexylamine, N,N-dicyclohexylamine, N-methyl-N-benzylamine, N-methylaniline, N-ethylaniline, N,N-diamylamine, N-methyl-N-2~ethylhexylamine, N-n-butyl-N-cyclohexylamine, N-methyl-N 2-heptylamine or N-propyl-N cyclohexylamine. The dibutylform-amides,including above all di-n-bukylformamide, have proved best for rOrmic acid, and N-n-butyl-N-2-ethylhexylacetamide and N-n-butyl-N-cyclohexYlacetamide have proved best for acetic acid.
The amides II are either known compounds or are readily accessible by conventional methods. If their ~reezing point is above the extraction temperature, it is necessary to use mixtures of the extractants II, or to work in the presence of a solvent, preferably an aromatic hydrocarbon such as p-diisopropylbenzene, which does not form an azeotrope with the acids. It is true that in this variant the efficiency of the extractant I~ is reduced, but nevertheless sufficient advantages over conventional methods remain, since the amount of solvent normally required to lower the ~reezing point is low, namely from 10 to 40% by weight, hased on II.
The partition coe~ficient, which is defined in Example 3 and -- 3 ~
~ 65~9 o. z . 31,607 is quoted for several acid/extractant systems is a measure of the suitability of the extractants. The lower is this coefficient, the greater the expense of the equipment required for the extraction~
However, it is not only the partition coeffi~ient for the acid but also the partition coefficient ~or water which has to be taken into account, since, naturally, the isolation of pure or concentrated acid requires less energy if the extractant takes up very little water; this latter condition is fulfilled satisfactorily by all of the extractants of the invention.
The requisite amount of extractant II depends on various para-meters, including, above all, the temperature, the amount and con-centration of acidg the number of separation stages and the other details of the equipment which affect equilibration and hence af~ect the residence time. The amount of extractant II required does not vary fundamentally with the particular extractant used and the particular acid involved.
The preferred temperature range for the extraction is from 0 to 70 C. It is true that at the lower end of this range, the extractant can absorb more acid than at higher temperatures, but on the other hand the rate of equilibration is lower. The economic optimum is in the range of from 20 to l10C.
In the range of fr~m 20 to 40C, from 1 to 10 kg of extractant II are normally required for extracting 1 kg of acid at a contact time Or from 1 to 5 minutes. The amount Or extractant is less ror longer contact times and vice versa. The stated contact times apply to the preferred embodiment of counter-current extraction, in a simple extraction column without other auxiliaries such as ba~les, trays or packing, and under Gonditions where the lighter extractant forms the continuous phase. The efficiency is increased by using multi-stage extraction apparatus, e.g. packed columns or tray columns with, preferably, from 3 to 6 theoretical plates, so that the amount of the extractant can be reduced in accordance with the conventional rules.
~ 4 --5 ~ ~ ~
OOZo 31,607 The above data-~elate to acid concentrations of from 5 to 50% by weight Or the aqueous solution, these being the most commonly encountered concentrations in industry. The depletion ratio, of from 95 to 99% by weight, is relatively constant, i.e.
if the initial solution is of 30% strength, from Oo l to 0O3 of acid remain in the aqueous medium, whilst if a 10% strength solution is extracted, a solution containing from 0005 to 001%
of acid remainsO In general3 it is most economical to take the exkraction to the point that a mixture of the extractant and an acid of from 10 to 40 per cent strength by weight is obtained.
The water is then distilled from this mixture, after which the acid is distilled off in a downstream columnO It is also possible3 using conventional methods, to use an arrangement where only a part of the water is removed in the first column, whilst in the second column the residual water is distilled off together with the acid. In that case, a commercial concentrated acid is obtained instead of the p~re acidO
The above comments relate to the continuous manufacture of carboxylic acids I, which in industry is virtually the only embodiment of importanceJ However, the process can of course also be carried out batchwise, if desired,in which case the general sense of the conditions outlined above must be adhered to.
It should be pointed out that the feature of the process which is essential to the invention is the nature of the ex-tractant, and not the extraction technique used, which is the conventional tec~nique~ To that extent, the condil;ions outlined merelY represent guidelines, from which it is possible to deviate~ in individual cases, in accordance with conventional rules and the conventional process technology, should this be advisable; an example is the treatment of effluent, where the purification of the water is more important than the isolation
3 651~8~
OOZ. 31,607 of the acidO Furthermore, it is posslble to use ~he stated extractants for the extractive distillation of the aqueous acidsO
The present process permits a substantial saving in energy and investment costs, both in comparison to other extraction processes and in comparison to distillative treatment~ It par-ticularly represents an advance where the isolation of pure or concentrated formic acid or acetic acid is concerned, and where aqueous solutions which con~ain several acids I have to be lQ worked up~
1 kg per hour of a 21 per cent strength by weight aqueous formic acid, as obtained by industrial synthesis from methanol and carbon monoxide, was fed, at from 20 to 25C, into the top of a packed column into which 0.9 kg per hour of di-n-butylformamide was fed, in counter-current, at the bottom. The extractant formed the continuous phase.
1.2 kg per hour of extract phase were taken o~f a settling zone at the upper end of the column; this phase contained vir-tually all the formic acid (210 g), together with 90 g of water, i.e. 300 g of 70% strength ~ormic acid. This acid was separated ~rom the extractant by simple continuous distillation in a packed column at 45C (column top temperature) and Go mm Hgo The extractant, which still contained traces of ~ormic acid, was recycled from the bottom of the distillation column to the extraction column.
In order to obtain ~ormic acid of about 90 per cent strength by weight, 70 g per hour of water were distilled from the extract phase first obtained, in a packed column (atmospheric pressure, bottom temperature lL~3C), after which the mixture ~0 remaining in the bottom of this column was subjected to a second distillation in a column with 25 bubble-cap trays, at 60 mm Hg .. . . . .
3~;1658~9 -~; OOZ~ 31,~07 and 42 C (column top temperature), giving a 90% strength acid as the distillateO
Using a similar method and employing the two columns, vir-tually anhydrous formic acid was obtained from the 90% acidO
1 kg per hour of a 15 per cent strength by weight aqueous acetic acid was fed, at room temperature, into the top of a column with 12 sieve tra~s, whilst 0.75 kg per hour of N-n-butyl-N-2-ethylhexylacetamide were fed in at the bottomO 81 per cent strength by weight acetic acid and anhydrous acetic acid were produced, by the method described in Example 1~ from the extract phase, which contained virtually all the acetic acid, together with 4% by weight of water, Since the suitability of the extractants depends above all on the partition coefficient concentration of the acid in the organic phase C = ~
concentration of the acid in the aqueous phase these coefficients were determined, for the practical require-ments of the present process, by stirring 100 g of the extrac-tant with 143 g of a 30 per cent strength by weight acid (cor-responding to 100 g of water) at 25C, until equilibrium was reached. The quotient C was then calculated from the acid con-centrations in the organic phase and in the aqueous phase.
The Table which follows gives a survey of the partition coefficients of some extractants according to the invention, and, by way of comparisD~, of some conventional extractantsO
F = formic acid A = acetic acid P - propionic acid Acr = acrylic acid ,: .
5~39 oO z o 31, 607 Extractant AcidPartition coefficient C
according to the invention N-Di-n-butylformamide F 1012 Acr 6.91 N-Di-n-butylacetamide F 1,33 N-Methyl-N-2-heptylformamide F 1018 N-n-Butyl-N-2-ethylhexylacetamide A 1007 N-n-Butyl-N-cyclohexylacetamide A 1039 50% by weigHt of N-di-n-butylformamide 50% by weight o~ N-di-cyclohexyl-formamide F 1~ o4 67% by weight of N~di-n-butylacetamide + ~ .
33% by weight of N-dicyclohexylacet-amide A1.4ll 80% by weight of N dl-n-butylformamide +
20% by weight of p-diisopropylbenzene F o.98 N-Ethyl-N-cyclohexylformamide F 1.26 N-Ethylformanilide F oO96 N-Dibutylpropionamide P 4002 conventional Benzene F 0.006 Methylene chloride F 00014 Trichloroethylene F 0O002 Diisopropyl ether F 00267 8 ~
OOZo 31,607 Extractant Acid Partition coeff'icient C
Isobutyl acetate F 0034 A oO56 Methyl isopropyl ketone F oO84 Acr 3049 Cyclohexyl formate F 0~31 Cyclohexanol F 0038 _ g _
OOZ. 31,607 of the acidO Furthermore, it is posslble to use ~he stated extractants for the extractive distillation of the aqueous acidsO
The present process permits a substantial saving in energy and investment costs, both in comparison to other extraction processes and in comparison to distillative treatment~ It par-ticularly represents an advance where the isolation of pure or concentrated formic acid or acetic acid is concerned, and where aqueous solutions which con~ain several acids I have to be lQ worked up~
1 kg per hour of a 21 per cent strength by weight aqueous formic acid, as obtained by industrial synthesis from methanol and carbon monoxide, was fed, at from 20 to 25C, into the top of a packed column into which 0.9 kg per hour of di-n-butylformamide was fed, in counter-current, at the bottom. The extractant formed the continuous phase.
1.2 kg per hour of extract phase were taken o~f a settling zone at the upper end of the column; this phase contained vir-tually all the formic acid (210 g), together with 90 g of water, i.e. 300 g of 70% strength ~ormic acid. This acid was separated ~rom the extractant by simple continuous distillation in a packed column at 45C (column top temperature) and Go mm Hgo The extractant, which still contained traces of ~ormic acid, was recycled from the bottom of the distillation column to the extraction column.
In order to obtain ~ormic acid of about 90 per cent strength by weight, 70 g per hour of water were distilled from the extract phase first obtained, in a packed column (atmospheric pressure, bottom temperature lL~3C), after which the mixture ~0 remaining in the bottom of this column was subjected to a second distillation in a column with 25 bubble-cap trays, at 60 mm Hg .. . . . .
3~;1658~9 -~; OOZ~ 31,~07 and 42 C (column top temperature), giving a 90% strength acid as the distillateO
Using a similar method and employing the two columns, vir-tually anhydrous formic acid was obtained from the 90% acidO
1 kg per hour of a 15 per cent strength by weight aqueous acetic acid was fed, at room temperature, into the top of a column with 12 sieve tra~s, whilst 0.75 kg per hour of N-n-butyl-N-2-ethylhexylacetamide were fed in at the bottomO 81 per cent strength by weight acetic acid and anhydrous acetic acid were produced, by the method described in Example 1~ from the extract phase, which contained virtually all the acetic acid, together with 4% by weight of water, Since the suitability of the extractants depends above all on the partition coefficient concentration of the acid in the organic phase C = ~
concentration of the acid in the aqueous phase these coefficients were determined, for the practical require-ments of the present process, by stirring 100 g of the extrac-tant with 143 g of a 30 per cent strength by weight acid (cor-responding to 100 g of water) at 25C, until equilibrium was reached. The quotient C was then calculated from the acid con-centrations in the organic phase and in the aqueous phase.
The Table which follows gives a survey of the partition coefficients of some extractants according to the invention, and, by way of comparisD~, of some conventional extractantsO
F = formic acid A = acetic acid P - propionic acid Acr = acrylic acid ,: .
5~39 oO z o 31, 607 Extractant AcidPartition coefficient C
according to the invention N-Di-n-butylformamide F 1012 Acr 6.91 N-Di-n-butylacetamide F 1,33 N-Methyl-N-2-heptylformamide F 1018 N-n-Butyl-N-2-ethylhexylacetamide A 1007 N-n-Butyl-N-cyclohexylacetamide A 1039 50% by weigHt of N-di-n-butylformamide 50% by weight o~ N-di-cyclohexyl-formamide F 1~ o4 67% by weight of N~di-n-butylacetamide + ~ .
33% by weight of N-dicyclohexylacet-amide A1.4ll 80% by weight of N dl-n-butylformamide +
20% by weight of p-diisopropylbenzene F o.98 N-Ethyl-N-cyclohexylformamide F 1.26 N-Ethylformanilide F oO96 N-Dibutylpropionamide P 4002 conventional Benzene F 0.006 Methylene chloride F 00014 Trichloroethylene F 0O002 Diisopropyl ether F 00267 8 ~
OOZo 31,607 Extractant Acid Partition coeff'icient C
Isobutyl acetate F 0034 A oO56 Methyl isopropyl ketone F oO84 Acr 3049 Cyclohexyl formate F 0~31 Cyclohexanol F 0038 _ g _
Claims (4)
1. A process for isolating a carboxylic acid of the general formula I
where R1 is hydrogen, methyl, ethyl or vinyl, from its aqueous solution by extracting the aqueous solution with an extractant and then distilling the mixture obtained, wherein the extractant used is a secondary amine of the general formula II
II
where R2 and R3 are alkyl, cycloalkyl, aryl or aralkyl or con-jointly are 1,4- or 1,5-alkylene, in each case of not more than 8 carbon atoms, with the proviso that the sum of the carbon atoms of R2 and R3 is from 7 to 14 and that only one of these radicals is aryl, and where R4 is one of the radicals R1.
where R1 is hydrogen, methyl, ethyl or vinyl, from its aqueous solution by extracting the aqueous solution with an extractant and then distilling the mixture obtained, wherein the extractant used is a secondary amine of the general formula II
II
where R2 and R3 are alkyl, cycloalkyl, aryl or aralkyl or con-jointly are 1,4- or 1,5-alkylene, in each case of not more than 8 carbon atoms, with the proviso that the sum of the carbon atoms of R2 and R3 is from 7 to 14 and that only one of these radicals is aryl, and where R4 is one of the radicals R1.
2. A process as claimed in claim 1, wherein R4 in the ex-tractant II is identical with R1 in the acid to be isolated.
3. A process as claimed in claim 1, wherein a N dibutyl-formamide is employed as the extractant for formic acid.
4. A process as claimed in claim 1, wherein N-n-butyl-2-ethylhexylacetamide or N-n-butyl-N-cyclohexylacetamide is employed as the extractant for acetic acid.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2545658A DE2545658C2 (en) | 1975-10-11 | 1975-10-11 | Process for the production of carboxylic acids from their aqueous solutions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1065889A true CA1065889A (en) | 1979-11-06 |
Family
ID=5958936
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA262,961A Expired CA1065889A (en) | 1975-10-11 | 1976-10-07 | Isolation of carboxylic acids from their aqueous solutions |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS6016410B2 (en) |
| BE (1) | BE847154A (en) |
| BR (1) | BR7606734A (en) |
| CA (1) | CA1065889A (en) |
| DE (1) | DE2545658C2 (en) |
| ES (1) | ES452288A1 (en) |
| FR (1) | FR2327215A1 (en) |
| GB (1) | GB1554172A (en) |
| IT (1) | IT1068121B (en) |
| NL (1) | NL188405C (en) |
| NO (1) | NO148068C (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2853991A1 (en) * | 1978-12-14 | 1980-07-03 | Basf Ag | METHOD FOR DETERMINING WATER-FREE OR MOSTLY WATER-FREE FORMIC ACID |
| DE2914671A1 (en) * | 1979-04-11 | 1980-10-23 | Basf Ag | METHOD FOR DETERMINING WATER-FREE OR MOSTLY WATER-FREE FORMIC ACID |
| NL8103517A (en) * | 1981-07-24 | 1983-02-16 | Badger Bv | METHOD FOR SEPARATING CARBONIC ACIDS FROM MIXTURES WITH NON-ACIDS BY AN ABSORPTION STRIP TREATMENT. |
| DE3411384A1 (en) * | 1984-03-28 | 1985-10-10 | Basf Ag, 6700 Ludwigshafen | METHOD FOR THE EXTRACTION OF WATER-FREE OR MOSTLY WATER-FREE FORMIC ACID BY HYDROLYSIS OF METHYLFORMIAT |
| DE3417790A1 (en) * | 1984-05-14 | 1985-11-14 | Basf Ag, 6700 Ludwigshafen | METHOD FOR PRODUCING FORMIC ACID |
| DE4023353A1 (en) * | 1990-07-23 | 1992-01-30 | Basf Ag | METHOD FOR OBTAINING CARBONIC ACIDS FROM THEIR AQUEOUS SOLUTIONS |
| DE4211141A1 (en) * | 1992-04-03 | 1993-10-07 | Basf Ag | Process for the preparation of formic acid by thermal cleavage of quaternary ammonium formates |
| US5728872A (en) * | 1994-06-27 | 1998-03-17 | Lutz Riemenschneider | Stabilized acrylic acid compositions |
| DE10002793A1 (en) * | 2000-01-24 | 2001-07-26 | Basf Ag | Production of anhydrous formic acid involves hydrolysis of methyl formate followed by distillation, extraction with amide and further distillations, using the amide also as a foam suppressant in first distillation stage |
| DE102008053315A1 (en) | 2008-10-27 | 2010-04-29 | Kiefer, Hans, Dr. | Preparation of tetrahydrofuran, comprises heating 1,4-diacetoxy butane in the presence of a strong acid and excess water to reflux and continuously separating the formed tetrahydrofuran by rectification |
| WO2012000964A1 (en) | 2010-06-29 | 2012-01-05 | Basf Se | Method for producing formic acid |
| US8901350B2 (en) | 2010-06-29 | 2014-12-02 | Basf Se | Process for the preparation of formic acid |
| CN104024203B (en) | 2011-12-20 | 2016-09-21 | 巴斯夫欧洲公司 | The method producing formic acid |
| US8889905B2 (en) | 2011-12-20 | 2014-11-18 | Basf Se | Process for preparing formic acid |
| RU2014129627A (en) | 2011-12-20 | 2016-02-10 | Басф Се | METHOD FOR PRODUCING FORMIC ACID |
| US8835683B2 (en) | 2011-12-20 | 2014-09-16 | Basf Se | Process for preparing formic acid |
| CN104812731A (en) | 2012-11-27 | 2015-07-29 | 巴斯夫欧洲公司 | Method for producing formic acid |
| US9428438B2 (en) | 2012-11-27 | 2016-08-30 | Basf Se | Process for preparing formic acid |
| CN109053421A (en) * | 2018-09-18 | 2018-12-21 | 福建师范大学福清分校 | The device and method of mixed acid waste water during a kind of extraction-partition wall rectification process Carboxylic Acid Fibre is plain |
| CN117545734A (en) | 2021-05-14 | 2024-02-09 | 瑞环控股株式会社 | Process for recovering carboxylic acid |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2408011A1 (en) * | 1974-02-20 | 1975-09-04 | Hoechst Ag | METHOD FOR OBTAINING TECHNICALLY PURE ACETIC ACID BY EXTRACTIVE DISTILLATION |
-
1975
- 1975-10-11 DE DE2545658A patent/DE2545658C2/en not_active Expired
-
1976
- 1976-09-29 IT IT27806/76A patent/IT1068121B/en active
- 1976-10-07 NL NLAANVRAGE7611111,A patent/NL188405C/en not_active IP Right Cessation
- 1976-10-07 CA CA262,961A patent/CA1065889A/en not_active Expired
- 1976-10-07 BR BR7606734A patent/BR7606734A/en unknown
- 1976-10-07 GB GB41693/76A patent/GB1554172A/en not_active Expired
- 1976-10-08 FR FR7630284A patent/FR2327215A1/en active Granted
- 1976-10-08 NO NO763447A patent/NO148068C/en unknown
- 1976-10-09 ES ES452288A patent/ES452288A1/en not_active Expired
- 1976-10-11 BE BE171402A patent/BE847154A/en not_active IP Right Cessation
- 1976-10-12 JP JP51121368A patent/JPS6016410B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6016410B2 (en) | 1985-04-25 |
| DE2545658C2 (en) | 1985-12-19 |
| NL188405C (en) | 1992-06-16 |
| NL7611111A (en) | 1977-04-13 |
| JPS5248614A (en) | 1977-04-18 |
| BR7606734A (en) | 1977-11-16 |
| GB1554172A (en) | 1979-10-17 |
| FR2327215A1 (en) | 1977-05-06 |
| NO148068C (en) | 1983-08-03 |
| DE2545658A1 (en) | 1977-04-21 |
| NO763447L (en) | 1977-04-13 |
| ES452288A1 (en) | 1978-03-01 |
| NO148068B (en) | 1983-04-25 |
| BE847154A (en) | 1977-04-12 |
| FR2327215B1 (en) | 1980-05-09 |
| IT1068121B (en) | 1985-03-21 |
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