WO2010027103A1 - Process for preparing fluorocarboxylic acid - Google Patents
Process for preparing fluorocarboxylic acid Download PDFInfo
- Publication number
- WO2010027103A1 WO2010027103A1 PCT/JP2009/065879 JP2009065879W WO2010027103A1 WO 2010027103 A1 WO2010027103 A1 WO 2010027103A1 JP 2009065879 W JP2009065879 W JP 2009065879W WO 2010027103 A1 WO2010027103 A1 WO 2010027103A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- fluorocarboxylic acid
- fluorocarboxylic
- mass
- phase
- acid
- Prior art date
Links
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
Definitions
- the present invention relates to a process for preparing a fluorocarboxylic acid. More particularly, it relates to a process for preparing a fluorocarboxylic acid in high purity and in high yield.
- Fluorocarboxylic acids such as C 8 fluorocarboxylic acids and their salts, are known to have excellent chemical stability based on good heat resistance, chemical resistance, and oxidation resistance, in addition to good surface activity.
- fluorocarboxylic acids as well as their ammonium salts and metal salts, are widely known as surfactants used for polymerization of fluoroolefins such as tetrafluoroethylene, surfactants for an aqueous dispersion, and water and oil repellents. It is well known that such fluorocarboxylic acids are generally prepared by hydrolyzing the corresponding fluorocarboxylic acid fluorides.
- the following process can be cited as an example of a process for preparing fluorocarboxylic acids. That is, the process comprises the steps of hydrolyzing fluorocarboxylic acid fluorides in the presence of a sulfuric acid aqueous solution to form a reaction product containing fluorocarboxylic acids and hydrogen fluorides, and removing at least some of the hydrofluoric acids from the reaction product by washing the reaction product with the sulfuric acid aqueous solution (for example, see Patent Document 1) .
- fluorocarboxylic acids are rendered into a molten state and separated into a hydrogen fluoride-containing sulfuric acid aqueous phase and a fluorocarboxylic acid-containing organic phase based on the low solubility of the fluorocarboxylic acids to the sulfuric acid aqueous solution.
- a fluorocarboxylic acid phase is obtained. Distillation is carried out on the fluorocarboxylic acid phase, so that fluorocarboxilic acids can be obtained in comparatively high purity.
- the above fluorocarboxylic acids can be prepared by recovering and regenerating the fluorocarboxylic acids after used in surfactants for polymerization (for example, see Patent Document 2) .
- Patent Document 1 JP-W 2006-500423
- Patent Document 2 JP-W 2006-501300
- the object of the present invention is to provide a process for industrially preparing a fluorocarboxylic acid in high purity and in high yield.
- the present invention is a process for preparing a fluorocarboxylic acid, which comprises: a dehydration step of removing from a mixture containing a fluorocarboxylic acid and water at least a part of said water to obtain a dehydrated fluorocarboxylic acid solution; and a purification step of purifying said dehydrated fluorocarboxylic acid solution.
- Patent Document 1 includes separation of a sulfuric acid aqueous phase from a fluorocarboxylic acid phase (hereinafter, referred to as liquid-liquid separation) .
- fluorocarboxylic acids obtained through this liquid-liquid separation may be further subjected to a simple distillation, so that fluorocarboxylic acids can be obtained in comparatively high purity.
- achieving the higher yield lowers the purity.
- Such behavior can be seen also in the fluorocarboxylic acids obtained by the process for preparing fluorocarboxylic acids by recovering and regenerating the same, which is disclosed in Patent Document 2.
- Fluorocarboxylic acids obtained by the above liquid-liquid separation contain at least a few percents of water.
- the fluorocarboxylic acids azeotrope with water, and form gel with water over a wide range in composition. Consequently, distillation presumably tends to be unstable.
- coexistence of water and the fluorocarboxylic acids having surface active properties presumably prevents purification, for example, by generating bubbles inside a distillation column.
- fluoroethercarboxylic acids represented by the general formula (i) :
- X-RfCOOH (i) wherein X is a H, F, or Cl, and Rf is a linear or branched fluoroalkylene group containing 4 to 14 carbon atoms, preferably 5 to 7 carbon atoms.
- Rf include a linear or branched fluoroalkylene group containing 7 carbon atoms, and particularly, a linear or branched perfluoroalkylene group.
- Examples of compounds represented by the general formula (i) include C 5 F H COOH, C 6 F I3 COOH, and C 7 Fi 5 COOH.
- C 5 F H COOH is desirable because it can be highly dehydrated, so that the compound in high purity is obtained ultimately.
- fluorocarboxylic acid there may also be mentioned fluoroethercarboxylic acids represented by the general formula (ii) :
- M 1 represents monovalent alkali metal, NH 4 or H;
- p represents 1 or 2;
- q represents 1 or 2;
- r represents 0, 1 or 2.
- fluoroethercarboxylic acid represented by the general formula (ii) there may be mentioned CF 3 OCF (CF 3 ) CF 2 OCF (CF 3 ) COONH 4 , CF 3 CF 2 OCF 2 CF 2 OCF 2 COONH 4 ,
- fluorocarboxylic acid there may also be mentioned fluoroethercarboxylic acids represented by the general formula (iii) :
- Desirable examples of compounds represented by the general formula (iii) include CF 3 -O-CF(CF 3 )CF 2 O-CF(CF 3 )COOH.
- fluorocarboxylic acid there may also be mentioned fluoroethercarboxylic acids represented by the general formula (iv) :
- fluorocarboxylic acid there may also be mentioned fluoroethercarboxylic acids represented by the general formula (v) :
- fluoroethercarboxylic acids represented by the general formula (vi) : Rf 3 OCF 2 CF 2 O(CF 2 ) P COOM 1 (vi) wherein Rf 3 represents a partially or wholly fluorine-substituted alkyl group, M 1 represents a monovalent alkali metal, NH 4 or H, p represents 1 or 2. Rf 3 is preferably an alkyl group containing 1 to 3 carbon atoms.
- fluoroethercarboxylic acid represented by the general formula (vi ) there may be mentioned CF 3 CF 2 OCF 2 CF 2 OCF 2 COONH 4 ,
- fluoroethercarboxylic acids represented by the general formula (vii) : Rf 4 OCHFCF 2 COOM 1 (vii) wherein Rf 4 represents a linear partially or wholly fluorine-substituted aliphatic group or a linear partially or wholly fluorine-substituted aliphatic group interrupted with one or more oxygen atoms, M 1 represents a monovalent alkali metal,
- Rf 4 is preferably an aliphatic group containing 1 to
- fluoroethercarboxylic acid represented by the general formula (vii) there may be mentioned CF 3 CF 2 OCF 2 CF 2 OCF 2 COONH 4 , CF 3 CF 2 OCF 2 CF 2 OCF 2 COOH, for instance.
- the preparation process of the present invention comprises a dehydration step of removing, from a mixture containing a fluorocarboxylic acid and water, at least a part of the water to obtain a dehydrated fluorocarboxylic acid solution.
- the dehydration step desirably includes adding concentrated sulfuric acid to the mixture containing a fluorocarboxylic acid and water. Addition of concentrated sulfuric acid advances the dehydration quite effectively.
- Solubility of a fluorocarboxylic acid to concentrated sulfuric acid and solubility of concentrated sulfuric acid to a fluorocarboxylic acid are both low. That means fine separability between a fluorocarboxylic acid phase and a concentrated sulfuric acid phase.
- the amount of the fluorocarboxylic acid in the organic phase is not particularly limited, and is desirably 80% by mass or more, and is more desirably 90% by mass or more.
- concentrated sulfuric acid refers to a sulfuric acid aqueous solution containing sulfuric acid at a concentration of 95% by mass or more.
- the concentrated sulfuric acid desirably has a sulfuric acid concentration of more than 95% by mass.
- the quantity ratio of the fluorocarboxylic acid and concentrated sulfuric acid to be used in the reaction is not particularly limited, as long as it can maintain the later-described sulfuric acid concentration.
- the dehydration step may be carried out under any suitable conditions with use of any suitable instruments, as long as the fluorocarboxylic acid is present in a liquid state.
- Dehydration is generally carried out at a temperature higher than the melting point of the fluorocarboxylic acid, normally at a temperature at least 3°C higher than the melting point, and desirably at a temperature at least 5°C higher than the melting point.
- dehydration is carried out at a temperature 5 to 15°C higher than the melting point.
- This condition can achieve substantially 100% dehydration in a comparatively short time.
- dehydration at a temperature of 60 to 70°C for two minutes can provide a dehydration product with the dehydration ratio of substantially 100%.
- dehydration reaction may be carried out either in a batchwise manner or in a continuous manner.
- Dehydration reaction in a batchwise manner is carried out as follows. First, a fluorocarboxylic acid and concentrated sulfuric acid are sufficiently mixed. Next, the mixed solution is allowed to stand so as to be separated into an aqueous phase containing sulfuric acids and an organic phase containing a target flurocarboxylic acid, and then, the organic phase is recovered. If needed, the obtained organic phase is again mixed with concentrated sulfuric acid and the mixture is placed still, so that the organic phase containing a smaller amount of water can be obtained. This operation is repeated until the water concentration in the organic phase has become lower than the desired level. [0030]
- the dehydration step is a kind of extraction operation, and therefore, an organic phase may be continuously contacted with an aqueous phase in a liquid-liquid heterophase dispersed system including an organic phase and an aqueous phase.
- an organic phase is desirably dispersed in an aqueous phase, or an aqueous phase is desirably dispersed in an organic phase.
- the dehydration reaction can be carried out by, for example, dispersing liquid droplets of a mixture (organic phase) of a fluorocarboxylic acid and water as the dispersed phase in the concentrated sulfuric acid (aqueous phase) as the continuous phase.
- the dehydration reaction is carried out by mixing the organic phase and the aqueous phase for a given period of time.
- the dehydrated fluorocarboxylic acid solution can be obtained by halting the mixing, subjecting the organic phase and the aqueous phase in the mixture to liquid separation, and collecting the organic phase.
- the dehydration step may include, in a liquid-liquid heterophase dispersed system including an aqueous phase and an organic phase, continuously contacting the organic phase with the aqueous phase, and separateing the organic phase and the aqueous phase.
- Fig. 1 shows a static mixer
- Fig.2 shows a liquid-liquid separation column.
- a fluorocarboxylic acid solution and concentrated sulfuric acid are together fed into the static mixer 10 from feed opening 11 and 12.
- a dehydration reaction is carried out continuously in the static mixer 10 and both liquids are sent to the liquid-liquid separation column 20 from a discharge opening 14.
- dehydration can be continuously carried out by feeding the mixture and a sulfuric acid to a contacting column so that they flow countercurrent to each other. More specifically, dehydration may be carried out as follows. Either of the mixture and the concentrated sulfuric acid is fed as the light (i.e. lower density) liquid and the other material is fed as the heavy (i.e.
- a mixture containing a fluorocarboxylic acid and water may be contacted with diphosphorus pentoxide and/or zeolite at a temperature equal to or higher than the melting point of the fluorocarboxylic acid.
- concentrated sulfuric acid is not necessarily added.
- at least one material selected from the group consisting of concentrated sulfuric acid, diphosphorus pentoxide, and zeolites may be added to the mixture containing a fluorucarboxylic acid and water. Examples of zeolites include aluminosilicate .
- the dehydrated fluorocarboxylic acid solution is obtainable after the dehydration reaction, and contains a fluorocarboxylic acid, sulfuric acid, and water.
- the dehydrated fluorocarboxylic acid solution desirably contains water at 1.0% by mass or less, because foaming and gel formation at purification can be avoided. If the water content is more than 1.0% by mass, a fluorocarboxylic acid may be ultimately obtained in lower purity and in lower yield.
- the water content is more desirably 0.7% by mass or less.
- the sulfuric acid concentration is desirably 70.0 to 99.9% by mass in the dehydration step.
- the sulfuric acid concentration is a sulfuric acid concentration of an aqueous phase (concentration to the total weight of the aqueous phase) in the dehydration step. If the sulfuric acid concentration is too low, the dehydration reaction may not proceed sufficiently.
- the sulfuric acid concentration is more desirably 80.0 to 99.9% by mass, further desirably 90.0 to 99.9% by mass, and particularly desirably 95.0 to 99.9% by mass.
- the mixture containing a fluorocarboxylic acid and water used in the dehydration step may be prepared by any suitable methods and may contain another component, as long as it does not adversely affect the process of the present invention.
- the mixture examples include a material obtainable from the process for obtaining a fluorocarboxylic acid by hydrolyzing or oxidizing fluorocarboxylic acid fluorides, fluorocarboxylates, or the like.
- the mixture may be obtained by following the method disclosed in Patent Documents 1 and 2, and the like.
- the dehydrated fluorocarboxylic acid solution obtained in the dehydration step is purified.
- the purification may be carried out by distillation, crystallization, and the like.
- the distillation is desirably multi-stage distillation, because a fluorocarboxylic acid can be obtained in high purity.
- the multi-stage distillation can be adopted, and therefore, it is possible to prepare a fluorocarboxylic acid in high purity by separating the target component and impurities in high yield.
- the fluorocarboxylic acid obtained by the process of the present invention may be treated with ammonia or alkali so as to be made into ammonium salts or alkali metal salts.
- the obtained material may be suitably used as a surfactant for polymerizing fluoromonomers and as a surfactant for stabilizing aqueous dispersion of fluoropolymers .
- Fig. 1 is a schematic view showing a static mixer.
- Fig. 2 is a schematic view showing a liquid-liquid separation column.
- Fig. 3 is a schematic view showing a Karr column extractor.
- compositions of a top phase and a bottom phase are determined by the following method.
- the concentration was measured by the HPLC method under the following conditions: Column Shodex 5C8 4D (produced by SHOWA DENKO K. K),
- Feeding quantity 100 ⁇ l, Column temperature: 4O 0 C,
- the water content was measured by the Karl Fischer method under the following conditions:
- a 50-ml erlenmeyer flask with a stirrer was used.
- Concentrated sulfuric acid (sulfuric acid concentration of 98% by mass, 10 g) was conditioned to have a temperature of 70°C in the flask and 10 g of C 7 Fi S COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 93.3% by mass of C 7 Fi 5 COOH, 6.3% by mass of water, and 0.4% by mass of sulfuric acids) was added thereto. Then, the mixture was stirred for 10 minutes and allowed to stand for 60 minutes, so that the mixture was separated into a top phase and a bottom phase.
- the top phase was an organic phase containing C 7 Fi 5 COOH and the bottom phase was an aqueous phase containing sulfuric acids and water.
- composition of the bottom phase was determined and the following results were obtained.
- Example 2 The same procedure as that in Example 1 was conducted, except that C 5 F H COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 93.8% by mass of C 5 F 11 COOH, 6.0% by mass of water, and 0.2% by mass of sulfuric acids) was used and the temperature was changed to 30°C. [0051] The top phase (dehydrated fluorocarboxylic acid (CsF 11 COOH) ) was separated and recovered, and its composition was determined. The following results were obtained.
- C 5 F H COOH mixture prepared by the method disclosed in Patent Document 1, a mixture containing 93.8% by mass of C 5 F 11 COOH, 6.0% by mass of water, and 0.2% by mass of sulfuric acids
- composition of the bottom phase was determined and the following result was obtained.
- Example 2 The same procedure as that in Example 1 was conducted, except that CF 3 OCF (CF 3 ) CF 2 OCF (CF 3 ) COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 91.4% by mass of CF 3 OCF(CF 3 )CF 2 OCF(CF 3 )COOH, 8.2% by mass of water, and 0.4% by mass of sulfuric acids) was used and the temperature was changed to 3O 0 C. [0055] The top phase (dehydrated fluorocarboxylic acid (CF 3 OCF(CF 3 )CF 2 OCF(CF 3 )COOH) ) was separated and recovered, and its composition was determined. The following results were obtained.
- composition of the bottom phase was determined and the following result was obtained.
- Multistage distillation was carried out on 200 g of the top phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained.
- the yield was 99.5% by mass.
- a sulfuric acid ion in a fluorocarboxylic acid distillate was below the detection limit.
- Example 4 The same procedure as that in Example 1 was conducted in each Reference Example, except that the amount of concentrated sulfuric acid to be used for dehydration was changed. Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration. [0059] Example 4
- Example 4 The same procedure as that in Example 1 was conducted, except that the amount of concentrated sulfuric acid to be used for dehydration was changed.
- the top phase was an aqueous phase containing sulfuric acids and water
- the bottom phase was an organic phase containing C 7 Fi S COOH. Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration.
- Multistage distillation was carried out on 200 g of the organic phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained.
- the yield represented table 1.
- a sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit.
- Example 1 The same procedure as that in Example 1 was conducted in each Reference Example, except that C 5 F 11 COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 93.8% by mass of C 5 F H COOH, 6.0% by mass of water, and 0.2% by mass of sulfuric acids) was used and the temperature was changed to 3O 0 C.
- Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration.
- Example 5 The same procedure as that in Example 1 was conducted in each Reference Example, except that C 5 F 11 COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 93.8% by mass of C 5 F H COOH, 6.0% by mass of water, and 0.2% by mass of sulfuric acids) was used and the temperature was changed to 3O 0 C.
- the top phase was an aqueous phase containing sulfuric acids and water
- the bottom phase was an organic phase containing C 5 F H COOH.
- Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration.
- Example 1 The same procedure as that in Example 1 was conducted in each Reference Example, except that CF 3 OCF(CF 3 )CF 2 OCF(CF 3 )COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 91.4% by mass of CF 3 OCF(CF 3 )CF 2 OCF(CF 3 )COOH, 8.2% by mass of water, and 0.4% by- mass of sulfuric acids) was used and the temperature was changed to 30 0 C.
- the top phase was an organic phase containing CF 3 OCF(CF 3 )CF 2 OCF(CF 3 )COOH
- the bottom phase was an aqueous phase containing sulfuric acids and water. Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration.
- Multistage distillation was carried out on 200 g of the organic phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained.
- Table 1 shows the yield.
- a sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit.
- Multistage distillation (10 trays) was conducted on 200 g of C 7 Fi 5 COOH mixture used in Example 1. However, foaming was found in the column and distillation could not be carried out. In the same manner, multistage distillation was respectively conducted on 200 g of C 5 F H COOH mixture used in Example 2 and 200 g of CF 3 OCF(CF 3 )CF 2 OCF(CF 3 )COOH mixture used in Example 3. Foaming in the column was found also in each of these cases, and distillation could not be carried out. [0072]
- Example 7 a static mixer 10 shown in Fig. 1 and a liquid-liquid separation column 20 shown in Fig. 2 were used.
- a static mixer with 12 pieces of elements 13 produced by Noritake Co., Limited was used as the static mixer.
- a column measuring 25 mm in diameter and 1300 mm in length was used as the liquid-liquid separation column.
- a fluorocarboxylic acid solution containing 93.3% by mass of C 5 F H COOH, 6.3% by mass of H 2 O, and 0.4% by mass of sulfuric acid, and concentrated sulfuric acid were together fed into the static mixer 10 from feed opening 11 and 12 at a flow rate of 25 cc/min.
- a dehydration reaction was carried out continuously in the static mixer 10 and both liquids were sent to the liquid-liquid separation column 20 from a discharge opening 14.
- Liquid-liquid separation of the both liquids fed from a feed opening 23 was carried out in the liquid-liquid separation column 20, and thereby a heavy liquid 21 and a light liquid 22 were obtained.
- a fluorocarboxylic acid phase (light liquid) separated in the liquid-liquid separation column 20 was recovered and the composition thereof was determined. The following result was obtained.
- Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained.
- the yield was 99.3% by mass .
- a sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit.
- a fluorocarboxylic acid phase was recovered in the same manner as in Example 7, except that the fluorocarboxylic acid solution having the below composition was used and the flow rate of the fluorocarboxylic acid solution and the concentrated sulfuric acid was changed. The composition thereof was determined and the results shown in Table 4 were obtained. [0078]
- Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained.
- the yield was 99.5% by mass .
- a sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit.
- a fluorocarboxylic acid phase was recovered in the same manner as in Example 7, except that the fluorocarboxylic acid solution having the below composition was used, and its composition was determined. The following results were obtained. [0083] The composition of the fluorocarboxylic acid solution C 7 Fi 5 COOH 92.6 % by mass H 2 O 6.8 % by mass H 2 SO 4 0.6 % by mass
- the Karr column extractor 30 shown in the fig.3 was used in Exmaple 10.
- the column has a cylindrical section 31 (length, 3.0 m) of 2.5 cm diameter, above and below which are positioned receptacles 33 and 34 as decanters.
- disk-like plates 55 plates positioned at 5 cm intervals
- a concentrated sulfuric acid solution (98% by mass) was continuously fed as the heavy liquid at a flow rate of 150 cc/min from the vicinity of the top end 37 of the cylindrical seciton.
- a fluorocarboxylic acid solution (C 5 FnCOOH 93% by mass, H 2 O 6.6% by mass, H 2 SO 4 0.4% by mass) was continuously fed as the light liquid at a flow rate of 150 cc/min from a feed opening 32 provided at a position 0.6 m from the bottom end 36 of the cylindrical section.
- the a fluorocarboxylic acid solution rose in the form of liquid droplets withiin the aqueous sulfuric acid solution.
- the water in the fluorocarboxylic acid solution was present in the fluorocarboxylic acid phase serving as the dispersed organic phase, but during continuously extracted
- a fluorocarboxylic acid phase was recovered in the same manner as in Example 10, except that the fluorocarboxylic acid solution having the below composition was used, and its composition was determined. The following results were obtained.
- the composition of the fluorocarboxylic acid solution is a fluorocarboxylic acid solution having the below composition.
- Example 12 A fluorocarboxylic acid phase was recovered in the same manner as in Example 10, except that the fluorocarboxylic acid solution having the below composition was used, and its composition was determined. The following results were obtained.
- composition of the fluorocarboxylic acid phase CF 3 OCF(CF 3 )CF 2 OCF(CF 3 )COOH 98.0 % by mass
- Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained.
- the yield was 98.1% by mass .
- a sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit.
- the process of the present invention can be suitably used as a process for preparing a fluorocarboxylic acid useful as a surfactant for polymerization.
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 object of the present invention is to provide a process for industrially preparing a fluorocarboxylic acid in high purity and in high yield. The present invention is a process for preparing a fluorocarboxylic acid, which comprises: a dehydration step of removing from a mixture containing a fluorocarboxylic acid and water at least a part of said water to obtain a dehydrated fluorocarboxylic acid solution; and a purification step of purifying said dehydrated fluorocarboxylic acid solution.
Description
DESCRIPTION
PROCESS FOR PREPARING FLUOROCARBOXYLIC ACID
CROSS-REFERENCE TO RELATED APPLICATIONS
This Application claims benefit under 35 U. S. C. §119 (e) of U.S. Provisional Application No.61/095, 107 filed September 8, 2008, incorporated herein by reference in its entirety.
TECHNICAL FIELD [0001]
The present invention relates to a process for preparing a fluorocarboxylic acid. More particularly, it relates to a process for preparing a fluorocarboxylic acid in high purity and in high yield.
BACKGROUND ART [0002] Fluorocarboxylic acids, such as C8 fluorocarboxylic acids and their salts, are known to have excellent chemical stability based on good heat resistance, chemical resistance, and oxidation resistance, in addition to good surface activity. These fluorocarboxylic acids, as well as their ammonium salts and metal salts, are widely known as surfactants used for polymerization of fluoroolefins such as tetrafluoroethylene, surfactants for an aqueous dispersion, and water and oil repellents. It is well known that such fluorocarboxylic acids are generally prepared by hydrolyzing the corresponding fluorocarboxylic acid fluorides. [0003]
The following process can be cited as an example of a process for preparing fluorocarboxylic acids. That is, the process comprises the steps of hydrolyzing fluorocarboxylic acid fluorides in the presence of a sulfuric acid aqueous
solution to form a reaction product containing fluorocarboxylic acids and hydrogen fluorides, and removing at least some of the hydrofluoric acids from the reaction product by washing the reaction product with the sulfuric acid aqueous solution (for example, see Patent Document 1) . In this method, at a temperature equal to or higher than the melting point of fluorocarboxylic acids, fluorocarboxylic acids are rendered into a molten state and separated into a hydrogen fluoride-containing sulfuric acid aqueous phase and a fluorocarboxylic acid-containing organic phase based on the low solubility of the fluorocarboxylic acids to the sulfuric acid aqueous solution. As a result, a fluorocarboxylic acid phase is obtained. Distillation is carried out on the fluorocarboxylic acid phase, so that fluorocarboxilic acids can be obtained in comparatively high purity. [0004]
In addition, the above fluorocarboxylic acids can be prepared by recovering and regenerating the fluorocarboxylic acids after used in surfactants for polymerization (for example, see Patent Document 2) . [0005]
Patent Document 1: JP-W 2006-500423 Patent Document 2: JP-W 2006-501300
SUMMARY OF THE INVENTION
[0006]
There is a need for a process for preparing fluorocarboxylic acids in higher purity and in higher yield compared to those achieved in the conventional process for preparing fluorocarboxylic acids. Accordingly, the object of the present invention is to provide a process for industrially preparing a fluorocarboxylic acid in high purity and in high yield.
[0007] The present invention is a process for preparing a
fluorocarboxylic acid, which comprises: a dehydration step of removing from a mixture containing a fluorocarboxylic acid and water at least a part of said water to obtain a dehydrated fluorocarboxylic acid solution; and a purification step of purifying said dehydrated fluorocarboxylic acid solution. [0008]
The present invention is specifically described in the following. [0009]
The process disclosed in Patent Document 1 includes separation of a sulfuric acid aqueous phase from a fluorocarboxylic acid phase (hereinafter, referred to as liquid-liquid separation) . As above described, fluorocarboxylic acids obtained through this liquid-liquid separation may be further subjected to a simple distillation, so that fluorocarboxylic acids can be obtained in comparatively high purity. However, there has been a problem that achieving the higher purity significantly lowers the yield. On the other hand, there has been a problem that achieving the higher yield lowers the purity. Such behavior can be seen also in the fluorocarboxylic acids obtained by the process for preparing fluorocarboxylic acids by recovering and regenerating the same, which is disclosed in Patent Document 2. [0010]
Research to clarify the reason for this has brought the inventors to reach the below presumption. Fluorocarboxylic acids obtained by the above liquid-liquid separation contain at least a few percents of water. Here, the fluorocarboxylic acids azeotrope with water, and form gel with water over a wide range in composition. Consequently, distillation presumably tends to be unstable. In addition, coexistence of water and the fluorocarboxylic acids having surface active properties presumably prevents purification, for example, by generating bubbles inside a distillation column.
[0011]
Based on these findings, the inventors have found out that preparation of fluorocarboxylic acids in high purity and in high yield is enabled by a dehydration step for obtaining a dehydrated fluorocarboxylic acid solution by removing at least a part of water contained in a mixture. Accordingly, the inventors have completed the present invention. [0012]
According to the process of the present invention, it is possible to prepare a fluorocarboxylic acid in high yield, without lowering the purity. [0013]
As the above-mentioned fluorocarboxylic acid, there may be mentioned fluoroethercarboxylic acids represented by the general formula (i) :
X-RfCOOH (i) wherein X is a H, F, or Cl, and Rf is a linear or branched fluoroalkylene group containing 4 to 14 carbon atoms, preferably 5 to 7 carbon atoms. Examples of Rf include a linear or branched fluoroalkylene group containing 7 carbon atoms, and particularly, a linear or branched perfluoroalkylene group. [0014]
Examples of compounds represented by the general formula (i) include C5FHCOOH, C6FI3COOH, and C7Fi5COOH. In particular, C5FHCOOH is desirable because it can be highly dehydrated, so that the compound in high purity is obtained ultimately. [0015]
As the above-mentioned fluorocarboxylic acid, there may also be mentioned fluoroethercarboxylic acids represented by the general formula (ii) :
X1 (CF2) P-O-CX2X3- (CF2) C3-O-CX4X5- (CF2) r-COOM1 ( ii ) in which X1, X2, X3, X4 and X5 are the same or different and each represents a H, F or CF3; M1 represents monovalent alkali metal, NH4 or H; p represents 1 or 2; q represents 1 or 2; r represents 0, 1 or 2. As a fluoroethercarboxylic acid
represented by the general formula (ii) , there may be mentioned CF3OCF (CF3) CF2OCF (CF3) COONH4, CF3CF2OCF2CF2OCF2COONH4 ,
CF3OCF2CF2CF2OCHFCF2COONH4, for instance. [0016] As the above-mentioned fluorocarboxylic acid, there may also be mentioned fluoroethercarboxylic acids represented by the general formula (iii) :
X- (CF2Jm-O- (CF(CF3)CF2O)n-CF(CF3)COOH (iii) wherein X is a H, F, or Cl, m is an integer from 1 to 10, such as 5, and n is an integer from 0 to 5, such as 1. [0017]
Desirable examples of compounds represented by the general formula (iii) include CF3-O-CF(CF3)CF2O-CF(CF3)COOH. [0018] As the above-mentioned fluorocarboxylic acid, there may also be mentioned fluoroethercarboxylic acids represented by the general formula (iv) :
X-(CF2J1n-O-(CF(CF3)CF2O)n-CHFCF2COOH (iv) wherein X, m, and n are defined as above. [0019]
As the above-mentioned fluorocarboxylic acid, there may also be mentioned fluoroethercarboxylic acids represented by the general formula (v) :
X-(CF2)H1-O-(CF(CF3)CF2O)n-CH2CF2COOH (v) wherein X, m, and n are defined as above. [0020]
As the above-mentioned fluorocarboxylic acid, there may also be mentioned fluoroethercarboxylic acids represented by the general formula (vi) : Rf3OCF2CF2O(CF2)PCOOM1 (vi) wherein Rf3 represents a partially or wholly fluorine-substituted alkyl group, M1 represents a monovalent alkali metal, NH4 or H, p represents 1 or 2. Rf3 is preferably an alkyl group containing 1 to 3 carbon atoms. As a fluoroethercarboxylic acid represented by the general formula
(vi ) , there may be mentioned CF3CF2OCF2CF2OCF2COONH4 ,
CF3CF2OCF2CF2OCF2COOH , for instance .
[ 0021 ]
As the above-mentioned fluorocarboxylic acid, there may also be mentioned fluoroethercarboxylic acids represented by the general formula (vii) : Rf4OCHFCF2COOM1 (vii) wherein Rf4 represents a linear partially or wholly fluorine-substituted aliphatic group or a linear partially or wholly fluorine-substituted aliphatic group interrupted with one or more oxygen atoms, M1 represents a monovalent alkali metal,
NH4 or H. Rf4 is preferably an aliphatic group containing 1 to
3 carbon atoms. As a fluoroethercarboxylic acid represented by the general formula (vii) , there may be mentioned CF3CF2OCF2CF2OCF2COONH4, CF3CF2OCF2CF2OCF2COOH, for instance.
[0022]
The preparation process of the present invention comprises a dehydration step of removing, from a mixture containing a fluorocarboxylic acid and water, at least a part of the water to obtain a dehydrated fluorocarboxylic acid solution.
[0023]
The dehydration step desirably includes adding concentrated sulfuric acid to the mixture containing a fluorocarboxylic acid and water. Addition of concentrated sulfuric acid advances the dehydration quite effectively.
[0024]
Solubility of a fluorocarboxylic acid to concentrated sulfuric acid and solubility of concentrated sulfuric acid to a fluorocarboxylic acid are both low. That means fine separability between a fluorocarboxylic acid phase and a concentrated sulfuric acid phase. The system allowed to stand easily forms a phase interface, and is separated into an aqueous phase mainly containing sulfuric acid and an organic phase mainly containing a fluorocarboxylic acid. Accordingly, the
dehydration step proceeds in a liquid (aqueous phase) -liquid (organic phase) heterophase dispersed (or mixed) system at any stage in the process from the addition of concentrated sulfuric acid to the completion of a dehydration reaction. The amount of the fluorocarboxylic acid in the organic phase is not particularly limited, and is desirably 80% by mass or more, and is more desirably 90% by mass or more. [0025]
Water is more likely to be present in the aqueous phase than in the organic phase containing carboxylic acids. Accordingly, after the completion of dehydration reaction, the aqueous phase is separated and the organic phase is recovered, and thus a dehydrated fluorocarboxylic acid solution is obtained. [0026]
In the present description, the term "concentrated sulfuric acid" refers to a sulfuric acid aqueous solution containing sulfuric acid at a concentration of 95% by mass or more. The concentrated sulfuric acid desirably has a sulfuric acid concentration of more than 95% by mass. [0027]
The quantity ratio of the fluorocarboxylic acid and concentrated sulfuric acid to be used in the reaction is not particularly limited, as long as it can maintain the later-described sulfuric acid concentration. [0028]
The dehydration step may be carried out under any suitable conditions with use of any suitable instruments, as long as the fluorocarboxylic acid is present in a liquid state. Dehydration is generally carried out at a temperature higher than the melting point of the fluorocarboxylic acid, normally at a temperature at least 3°C higher than the melting point, and desirably at a temperature at least 5°C higher than the melting point. For example, dehydration is carried out at a temperature 5 to 15°C higher than the melting point. This
condition can achieve substantially 100% dehydration in a comparatively short time. For example, in the case of preparing a linear C7Fi5COOH, dehydration at a temperature of 60 to 70°C for two minutes can provide a dehydration product with the dehydration ratio of substantially 100%. [0029]
In the present invention, dehydration reaction may be carried out either in a batchwise manner or in a continuous manner. Dehydration reaction in a batchwise manner is carried out as follows. First, a fluorocarboxylic acid and concentrated sulfuric acid are sufficiently mixed. Next, the mixed solution is allowed to stand so as to be separated into an aqueous phase containing sulfuric acids and an organic phase containing a target flurocarboxylic acid, and then, the organic phase is recovered. If needed, the obtained organic phase is again mixed with concentrated sulfuric acid and the mixture is placed still, so that the organic phase containing a smaller amount of water can be obtained. This operation is repeated until the water concentration in the organic phase has become lower than the desired level. [0030]
The dehydration step is a kind of extraction operation, and therefore, an organic phase may be continuously contacted with an aqueous phase in a liquid-liquid heterophase dispersed system including an organic phase and an aqueous phase. For example, an organic phase is desirably dispersed in an aqueous phase, or an aqueous phase is desirably dispersed in an organic phase. More specifically, the dehydration reaction can be carried out by, for example, dispersing liquid droplets of a mixture (organic phase) of a fluorocarboxylic acid and water as the dispersed phase in the concentrated sulfuric acid (aqueous phase) as the continuous phase. It promotes contact and material transfer between the aqueous phase as the continuous phase and the organic phase as the dispersed phase, so that dehydration reaction subsequently proceeds. The
dispersed phase and the continuous phase may be reversed. The dehydration reaction is carried out by mixing the organic phase and the aqueous phase for a given period of time. The dehydrated fluorocarboxylic acid solution can be obtained by halting the mixing, subjecting the organic phase and the aqueous phase in the mixture to liquid separation, and collecting the organic phase.
Also, the dehydration step may include, in a liquid-liquid heterophase dispersed system including an aqueous phase and an organic phase, continuously contacting the organic phase with the aqueous phase, and separateing the organic phase and the aqueous phase. Fig. 1 shows a static mixer, Fig.2 shows a liquid-liquid separation column. A fluorocarboxylic acid solution and concentrated sulfuric acid are together fed into the static mixer 10 from feed opening 11 and 12. A dehydration reaction is carried out continuously in the static mixer 10 and both liquids are sent to the liquid-liquid separation column 20 from a discharge opening 14. Liquid-liquid separation of the both liquids fed from a feed opening 23 is carried out in the liquid-liquid separation column 20, and thereby a heavy liquid 21 and a light liquid 22 are obtained. A fluorocarboxylic acid phase separated in the liquid-liquid separation column 20 can be recovered. [0031] In the dehydration step, dehydration can be continuously carried out by feeding the mixture and a sulfuric acid to a contacting column so that they flow countercurrent to each other. More specifically, dehydration may be carried out as follows. Either of the mixture and the concentrated sulfuric acid is fed as the light (i.e. lower density) liquid and the other material is fed as the heavy (i.e. higher density) liquid into a differential contacting extraction device, so to say "an extraction column (for example, Karr column extractor and the like) ". Then, countercurrent contact is induced between the two liquids . The operation may be carried out with the aqueous phase
serving as the continuous phase, and the organic phase serving as the dispersed phase, and vice versa.
[0032]
In the dehydration step, a mixture containing a fluorocarboxylic acid and water may be contacted with diphosphorus pentoxide and/or zeolite at a temperature equal to or higher than the melting point of the fluorocarboxylic acid. In this case, concentrated sulfuric acid is not necessarily added. Namely, in the dehydration step, at least one material selected from the group consisting of concentrated sulfuric acid, diphosphorus pentoxide, and zeolites may be added to the mixture containing a fluorucarboxylic acid and water. Examples of zeolites include aluminosilicate . [0033] The dehydrated fluorocarboxylic acid solution is obtainable after the dehydration reaction, and contains a fluorocarboxylic acid, sulfuric acid, and water. The dehydrated fluorocarboxylic acid solution desirably contains water at 1.0% by mass or less, because foaming and gel formation at purification can be avoided. If the water content is more than 1.0% by mass, a fluorocarboxylic acid may be ultimately obtained in lower purity and in lower yield. The water content is more desirably 0.7% by mass or less. [0034] The sulfuric acid concentration is desirably 70.0 to 99.9% by mass in the dehydration step. The sulfuric acid concentration is a sulfuric acid concentration of an aqueous phase (concentration to the total weight of the aqueous phase) in the dehydration step. If the sulfuric acid concentration is too low, the dehydration reaction may not proceed sufficiently. The sulfuric acid concentration is more desirably 80.0 to 99.9% by mass, further desirably 90.0 to 99.9% by mass, and particularly desirably 95.0 to 99.9% by mass. [0035] The mixture containing a fluorocarboxylic acid and water
used in the dehydration step may be prepared by any suitable methods and may contain another component, as long as it does not adversely affect the process of the present invention. Examples of the mixture include a material obtainable from the process for obtaining a fluorocarboxylic acid by hydrolyzing or oxidizing fluorocarboxylic acid fluorides, fluorocarboxylates, or the like. The mixture may be obtained by following the method disclosed in Patent Documents 1 and 2, and the like. [0036]
In the purification step, the dehydrated fluorocarboxylic acid solution obtained in the dehydration step is purified. The purification may be carried out by distillation, crystallization, and the like. The distillation is desirably multi-stage distillation, because a fluorocarboxylic acid can be obtained in high purity. [0037]
In the process of the present invention, the multi-stage distillation can be adopted, and therefore, it is possible to prepare a fluorocarboxylic acid in high purity by separating the target component and impurities in high yield. [0038]
The fluorocarboxylic acid obtained by the process of the present invention may be treated with ammonia or alkali so as to be made into ammonium salts or alkali metal salts. The obtained material may be suitably used as a surfactant for polymerizing fluoromonomers and as a surfactant for stabilizing aqueous dispersion of fluoropolymers .
EFFECT OF THE INVENTION
[0039]
The process of the present invention is as above described, and therefore, it is possible to prepare a fluorocarboxylic acid in high purity and in high yield.
[0040]
BRIEF DESCRIPTION OF THE DRAWINGS
[Fig. 1] Fig. 1 is a schematic view showing a static mixer. [Fig. 2] Fig. 2 is a schematic view showing a liquid-liquid separation column.
[Fig. 3] Fig. 3 is a schematic view showing a Karr column extractor.
BEST MODE FOR CARRYING OUT THE INVENTION [0041]
Examples and Comparative Examples are shown in the following, and the present invention is specifically described.
[0042]
In the present examples, compositions of a top phase and a bottom phase are determined by the following method.
[0043]
Concentration of the fluorocarboxylic acid
The concentration was measured by the HPLC method under the following conditions: Column Shodex 5C8 4D (produced by SHOWA DENKO K. K),
Mobile phase: acetonitrile/0.6% by mass per chloric acid aqueous solution = 1/1 (vol/vol) ,
Current speed: 1.0 ml/min.,
Feeding quantity: 100 μl, Column temperature: 4O0C,
Detection: UV 210 ran.
[0044]
Water content
The water content was measured by the Karl Fischer method under the following conditions:
Reagent AQUAMICRON AKX/CXU (produced by Mitsubishi
Chemical Corporation)
Measurement: Electometric titration
[0045] Sulfuric acid ion concentration
The concentration was measured by ion chromatography under the following conditions:
Column: IonPac AS4A (4 x 250 mm) (produced by Nippon Dionex K. K.) Mobile phase: sodium carbonate (2.5 mmol/1) and sodium hydrogen carbonate (1 mmol/1) Current speed: 0.5 ml/min., Feeding quantity: 50 μl,
Detector: electric conductivity detector. [0046]
Example 1
A 50-ml erlenmeyer flask with a stirrer was used. Concentrated sulfuric acid (sulfuric acid concentration of 98% by mass, 10 g) was conditioned to have a temperature of 70°C in the flask and 10 g of C7FiSCOOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 93.3% by mass of C7Fi5COOH, 6.3% by mass of water, and 0.4% by mass of sulfuric acids) was added thereto. Then, the mixture was stirred for 10 minutes and allowed to stand for 60 minutes, so that the mixture was separated into a top phase and a bottom phase. The top phase was an organic phase containing C7Fi5COOH and the bottom phase was an aqueous phase containing sulfuric acids and water.
[0047] The top phase (dehydrated fluorocarboxylic acid
(C7Fi5COOH) ) was separated and recovered, and its composition was determined. The following results were obtained.
C7Fi5COOH 99% by mass
H2O 6800 ppm by mass [0048]
The composition of the bottom phase was determined and the following results were obtained.
C7Fi5COOH 1500 ppm by mass
H2SO4 95% by mass [ 0049 ]
Multistage distillation was carried out on 200 g of the top phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 99.3% by mass. A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit. [0050] Example 2
The same procedure as that in Example 1 was conducted, except that C5FHCOOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 93.8% by mass of C5F11COOH, 6.0% by mass of water, and 0.2% by mass of sulfuric acids) was used and the temperature was changed to 30°C. [0051] The top phase (dehydrated fluorocarboxylic acid (CsF11COOH) ) was separated and recovered, and its composition was determined. The following results were obtained.
C5F11COOH 99% by mass
H2O 400 ppm by mass [0052]
The composition of the bottom phase was determined and the following result was obtained.
H2SO4 94% by mass [0053] Multistage distillation was carried out on 200 g of the top phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 99.7% by mass . A sulfuric acid ion in a fluorocarboxylic acid distillate was below the detection limit. [0054] Example 3
The same procedure as that in Example 1 was conducted, except that CF3OCF (CF3) CF2OCF (CF3) COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing
91.4% by mass of CF3OCF(CF3)CF2OCF(CF3)COOH, 8.2% by mass of water, and 0.4% by mass of sulfuric acids) was used and the temperature was changed to 3O0C. [0055] The top phase (dehydrated fluorocarboxylic acid (CF3OCF(CF3)CF2OCF(CF3)COOH) ) was separated and recovered, and its composition was determined. The following results were obtained.
CF3OCF(CF3)CF2OCF(CF3)COOH 99% by mass H2O 450 ppm by mass [0056]
The composition of the bottom phase was determined and the following result was obtained.
H2SO4 91% by mass [0057]
Multistage distillation was carried out on 200 g of the top phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 99.5% by mass. A sulfuric acid ion in a fluorocarboxylic acid distillate was below the detection limit. [0058] Reference Examples 1 and 2
The same procedure as that in Example 1 was conducted in each Reference Example, except that the amount of concentrated sulfuric acid to be used for dehydration was changed. Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration. [0059] Example 4
The same procedure as that in Example 1 was conducted, except that the amount of concentrated sulfuric acid to be used for dehydration was changed. In Example 4, the top phase was an aqueous phase containing sulfuric acids and water, and the bottom phase was an organic phase containing C7FiSCOOH. Table
1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration.
[0060]
Multistage distillation was carried out on 200 g of the organic phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield represented table 1. A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit. [0061]
Reference Examples 3 to 4
The same procedure as that in Example 1 was conducted in each Reference Example, except that C5F11COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 93.8% by mass of C5FHCOOH, 6.0% by mass of water, and 0.2% by mass of sulfuric acids) was used and the temperature was changed to 3O0C. Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration. [0062]
Example 5
The same procedure as that in Example 1 was conducted in each Reference Example, except that C5F11COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 93.8% by mass of C5FHCOOH, 6.0% by mass of water, and 0.2% by mass of sulfuric acids) was used and the temperature was changed to 3O0C. In Example 5, the top phase was an aqueous phase containing sulfuric acids and water, and the bottom phase was an organic phase containing C5FHCOOH. Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration. [0063]
Multistage distillation was carried out on 200 g of the organic phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified
fluorocarboxylic acid was obtained. The yield represented table 1. A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit. [0064] Reference Examples 5 and 6
The same procedure as that in Example 1 was conducted in each Reference Example, except that CF3OCF(CF3)CF2OCF(CF3)COOH mixture (prepared by the method disclosed in Patent Document 1, a mixture containing 91.4% by mass of CF3OCF(CF3)CF2OCF(CF3)COOH, 8.2% by mass of water, and 0.4% by- mass of sulfuric acids) was used and the temperature was changed to 300C. In both of Reference Examples, the top phase was an organic phase containing CF3OCF(CF3)CF2OCF(CF3)COOH, and the bottom phase was an aqueous phase containing sulfuric acids and water. Table 1 shows the results of analysis of the organic phase and the aqueous phase obtained after dehydration.
[0065]
Example 6
The same procedure as that in Reference Example 5 was conducted, except that the amount of concentrated sulfuric acid to be used for dehydration was changed.
[0066]
Multistage distillation was carried out on 200 g of the organic phase (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. Table 1 shows the yield.
A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit.
[0068]
Reference Example 7
In order to confirm that multistage distillation of the dehydrated carboxylic acid can provide a carboxylic acid in high purity, multistage distillation was carried out on the mixed solution containing 200 g of CF3OCF(CF3)CF2OCF(CF3)COOH, 6.O g of C7Fi5COOH, and 6.0 g of C5FHCOOH, and having a water concentration of 600 ppm by mass. Examination was carried out in a 15-tray Oldershaw distillation column, and the distillate was separated into 8 parts and respectively collected. Table 2 shows the results of analysis of C5FHCOOH concentration and C7Fi5COOH concentration of each distillate. [0069] [Table 2]
[0070]
As shown in Table 2, C5FHCOOH and C7Fi5COOH were not contained in distillates 5 and 6. Accordingly, it was found out that C5FHCOOH can be adequately removed as the first distillate and C7Fi5COOH can be removed as the latter distillate . Namely, it was possible to obtain CF3OCF (CF3) CF2OCF (CF3) COOH in high purity. [0071] Comparative Example
Multistage distillation (10 trays) was conducted on 200 g of C7Fi5COOH mixture used in Example 1. However, foaming was found in the column and distillation could not be carried out. In the same manner, multistage distillation was respectively conducted on 200 g of C5FHCOOH mixture used in Example 2 and 200 g of CF3OCF(CF3)CF2OCF(CF3)COOH mixture used in Example 3. Foaming in the column was found also in each of these cases, and distillation could not be carried out. [0072] Example 7
In Example 7, a static mixer 10 shown in Fig. 1 and a liquid-liquid separation column 20 shown in Fig. 2 were used. A static mixer with 12 pieces of elements 13 produced by Noritake Co., Limited was used as the static mixer. A column measuring 25 mm in diameter and 1300 mm in length was used as the liquid-liquid separation column. [0073]
A fluorocarboxylic acid solution containing 93.3% by mass of C5FHCOOH, 6.3% by mass of H2O, and 0.4% by mass of sulfuric acid, and concentrated sulfuric acid were together fed into the static mixer 10 from feed opening 11 and 12 at a flow rate of 25 cc/min. A dehydration reaction was carried out continuously in the static mixer 10 and both liquids were sent to the liquid-liquid separation column 20 from a discharge opening 14. Liquid-liquid separation of the both liquids fed from a feed opening 23 was carried out in the liquid-liquid separation column 20, and thereby a heavy liquid 21 and a light liquid 22
were obtained. A fluorocarboxylic acid phase (light liquid) separated in the liquid-liquid separation column 20 was recovered and the composition thereof was determined. The following result was obtained.
C5FHCOOH 99.2% by mass
H2O 340 ppm by mass [0074]
Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 99.3% by mass . A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit. [0075] Reference Examples 8 to 10
In each Example, a fluorocarboxylic acid phase was recovered in the same manner as in Example 7, except that the flow rate of the fluorocarboxylic acid solution. The composition thereof was determined and the results shown in Table 3 were obtained. [0076] [Table 3]
[0077] Example 8
A fluorocarboxylic acid phase was recovered in the same manner as in Example 7, except that the fluorocarboxylic acid
solution having the below composition was used and the flow rate of the fluorocarboxylic acid solution and the concentrated sulfuric acid was changed. The composition thereof was determined and the results shown in Table 4 were obtained. [0078]
Composition of the fluorocarboxylic acid solution CF3OCF(CF3)CF2OCF(CF3)COOH 92.2% by mass H2O 7.5% by mass H2SO4 0.3% by mass [0079]
Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 99.5% by mass . A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit.
[0080] Reference Examples 11 to 13
In each Example, a fluorocarboxylic acid phase was recovered in the same manner as in Example 8, except that the flow rate of the fluorocarboxylic acid solution and the concentrated sulfuric acid was changed. The composition thereof was determined and the results shown in Table 4 were obtained. [0081]
[Table 4]
[0082] Example 9
A fluorocarboxylic acid phase was recovered in the same manner as in Example 7, except that the fluorocarboxylic acid solution having the below composition was used, and its composition was determined. The following results were obtained. [0083] The composition of the fluorocarboxylic acid solution C7Fi5COOH 92.6 % by mass H2O 6.8 % by mass H2SO4 0.6 % by mass
The composition of the fluorocarboxylic acid phase C7Fi5COOH 98.9 % by mass
H2O 0.6 % by mass [0084]
Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 99.3% by mass . A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit. [0085]
Example 10
The Karr column extractor 30 shown in the fig.3 was used in Exmaple 10. The column has a cylindrical section 31 (length, 3.0 m) of 2.5 cm diameter, above and below which are positioned receptacles 33 and 34 as decanters. At the interior of the cylindrical section 31, disk-like plates (55 plates positioned at 5 cm intervals) are moved vertically so as to agitate the liquid within the cylindrical section. [0086] A concentrated sulfuric acid solution (98% by mass) was continuously fed as the heavy liquid at a flow rate of 150 cc/min from the vicinity of the top end 37 of the cylindrical seciton. A fluorocarboxylic acid solution (C5FnCOOH 93% by mass, H2O 6.6% by mass, H2SO4 0.4% by mass) was continuously fed as the light liquid at a flow rate of 150 cc/min from a feed opening 32 provided at a position 0.6 m from the bottom end 36 of the cylindrical section. The a fluorocarboxylic acid solution rose in the form of liquid droplets withiin the aqueous sulfuric acid solution. [0087]
The water in the fluorocarboxylic acid solution was present in the fluorocarboxylic acid phase serving as the dispersed organic phase, but during continuously extracted
(i.e., dehydrated) at the dehydrating zone 35 by the sulfuric acid solution rising up through the column. The liquid droplets of fluorocarboxylic acid phase (dispersed phase) that had descended coalesce in the decanter 33 at the top of the column and liquid separation occurred, resulting in the formation of an interface with the aqueous sulfuric acid solution. [0088]
The fluorocarboxylic acid phase that formed in the decanter 33 at the top of the column was recovered, and its composition was determined. The following results were obtained.
C5FHCOOH 98.1 % by mass
H2O 2260 ppm by mass
H2SO4 1.7 % by mass [0089] Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 98.2% by mass . A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit. [0090] Example 11
A fluorocarboxylic acid phase was recovered in the same manner as in Example 10, except that the fluorocarboxylic acid solution having the below composition was used, and its composition was determined. The following results were obtained. The composition of the fluorocarboxylic acid solution
CF3OCF(CF3)CF2OCF(CF3)COOH 95.0 % by mass H2O 4.7 % by mass
H2SO4 0.3 % by mass The composition of the fluorocarboxylic acid phase
CF3OCF(CF3)CF2OCF(CF3)COOH 98.8 % by mass
H2O 1530 ppm by mass H2SO4 1.0 % by mass [0091]
Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 98.3% by mass . A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit. [0092] Example 12 A fluorocarboxylic acid phase was recovered in the same
manner as in Example 10, except that the fluorocarboxylic acid solution having the below composition was used, and its composition was determined. The following results were obtained. The composition of the fluorocarboxylic acid solution C7Fi5COOH 92.6 % by mass H2O 6.8 % by mass H2SO4 0.6 % by mass
The composition of the fluorocarboxylic acid phase CF3OCF(CF3)CF2OCF(CF3)COOH 98.0 % by mass
H2O 0.8 % by mass [0093]
Multistage distillation was carried out on 200 g of the light liquid (dehydrated fluorocarboxylic acid) in a 10-tray Oldershaw distillation column, so that the purified fluorocarboxylic acid was obtained. The yield was 98.1% by mass . A sulfuric acid ion in the obtained fluorocarboxylic acid distillate was below the detection limit.
INDUSTRIAL APPLICABILITY
[0094]
The process of the present invention can be suitably used as a process for preparing a fluorocarboxylic acid useful as a surfactant for polymerization.
[0095]
EXPLANATION OF NUMERALS AND SYMBOLS
10 - static mixer
11, 12, 23 - feed opening 13 - element
14 - discharge opening
20 - liquid-liquid separation column
21 - heavy liquid
22 - light liquid 30 - Karr column extractor
.
31 - cylindrical section 33, 34 - receptacle
35 - dehydrating zone
36 - bottom end of cylindrical section 37 - top end of cylindrical section
Claims
1. A process for preparing a fluorocarboxylic acid, which comprises : a dehydration step of removing from a mixture containing a fluorocarboxylic acid and water at least a part of said water to obtain a dehydrated fluorocarboxylic acid solution; and a purification step of purifying said dehydrated fluorocarboxylic acid solution.
2. The process of claim 1, wherein the dehydration step includes adding concentrated sulfuric acid to the mixture containing a fluorocarboxylic acid and water.
3. The process of claim 1 or 2, wherein the dehydration step proceeds in a liquid-liquid heterophase dispersed system including an aqueous phase and an organic phase, and said aqueous phase has a sulfuric acid concentration of 70.0 to 99.9% by mass.
4. The process of claim 1, 2, or 3, wherein the dehydration step includes, in a liquid-liquid heterophase dispersed system including an aqueous phase and an organic phase, continuously contacting the organic phase with the aqueous phase.
5. The process of claim 1, 2, 3 or 4, wherein the dehydration step includes, in a liquid-liquid heterophase dispersed system including an aqueous phase and an organic phase, continuously contacting the organic phase with the aqueous phase, and separateing the organic phase and the aqueous phase.
6. The process of claim 1, 2, 3, or 4, wherein the dehydration step includes continuously carrying out dehydration by feeding the said mixture and a sulfuric acid to a contacting column so that they flow countercurrent to each other.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN2009801328839A CN102131759B (en) | 2008-09-08 | 2009-09-04 | Process for preparing fluorocarboxylic acid |
US13/055,095 US8624060B2 (en) | 2008-09-08 | 2009-09-04 | Process for preparing fluorocarboxylic acid |
EP09811623.9A EP2321248B1 (en) | 2008-09-08 | 2009-09-04 | Process for preparing fluorocarboxylic acid |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US9510708P | 2008-09-08 | 2008-09-08 | |
US61/095,107 | 2008-09-08 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2010027103A1 true WO2010027103A1 (en) | 2010-03-11 |
Family
ID=41797262
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2009/065879 WO2010027103A1 (en) | 2008-09-08 | 2009-09-04 | Process for preparing fluorocarboxylic acid |
Country Status (5)
Country | Link |
---|---|
US (1) | US8624060B2 (en) |
EP (1) | EP2321248B1 (en) |
JP (1) | JP5347851B2 (en) |
CN (1) | CN102131759B (en) |
WO (1) | WO2010027103A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3473610A4 (en) * | 2016-06-16 | 2020-02-12 | Daikin Industries, Ltd. | Method of producing c2 c20 fluorine-containing organic acid, and composition containing c2 c20 fluorine-containing organic acid |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH06128189A (en) * | 1991-04-26 | 1994-05-10 | Hoechst Ag | Preparation of perfluoroether carboxylic acid |
JP2006500423A (en) | 2002-09-25 | 2006-01-05 | イー・アイ・デュポン・ドゥ・ヌムール・アンド・カンパニー | Method for producing fluorocarboxylic acid |
JP2006501300A (en) | 2002-09-30 | 2006-01-12 | ダイキン工業株式会社 | Method for producing fluorocarboxylic acid |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3513203A (en) | 1966-07-11 | 1970-05-19 | Montedison Spa | Fluorinated ketones and process for their preparation |
JPS5857333A (en) * | 1981-09-30 | 1983-04-05 | Daikin Ind Ltd | Production of perfluoro-2-alkoxyfatty acid fluoride |
US4889656A (en) * | 1987-10-30 | 1989-12-26 | Minnesota Mining And Manufacturing Company | Perfluoro(cycloaliphatic methyleneoxyalkylene) carbonyl fluorides and derivatives thereof |
DE4213154C1 (en) * | 1992-04-22 | 1993-06-17 | Hoechst Ag, 6230 Frankfurt, De | |
JP5055652B2 (en) | 2000-08-11 | 2012-10-24 | ダイキン工業株式会社 | Method for recovering fluorine-containing surfactant |
JP4904761B2 (en) * | 2005-09-30 | 2012-03-28 | ユニマテック株式会社 | Method for recovering fluorinated carboxylic acid |
-
2009
- 2009-09-02 JP JP2009202583A patent/JP5347851B2/en active Active
- 2009-09-04 WO PCT/JP2009/065879 patent/WO2010027103A1/en active Application Filing
- 2009-09-04 EP EP09811623.9A patent/EP2321248B1/en active Active
- 2009-09-04 US US13/055,095 patent/US8624060B2/en active Active
- 2009-09-04 CN CN2009801328839A patent/CN102131759B/en active Active
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH06128189A (en) * | 1991-04-26 | 1994-05-10 | Hoechst Ag | Preparation of perfluoroether carboxylic acid |
JP2006500423A (en) | 2002-09-25 | 2006-01-05 | イー・アイ・デュポン・ドゥ・ヌムール・アンド・カンパニー | Method for producing fluorocarboxylic acid |
JP2006501300A (en) | 2002-09-30 | 2006-01-12 | ダイキン工業株式会社 | Method for producing fluorocarboxylic acid |
Non-Patent Citations (1)
Title |
---|
See also references of EP2321248A4 |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3473610A4 (en) * | 2016-06-16 | 2020-02-12 | Daikin Industries, Ltd. | Method of producing c2 c20 fluorine-containing organic acid, and composition containing c2 c20 fluorine-containing organic acid |
US10759731B2 (en) | 2016-06-16 | 2020-09-01 | Daikin Industries, Ltd. | Method for producing C2-C20 fluorine-containing organic acid, and composition comprising C2-C20 fluorine-containing organic acid |
Also Published As
Publication number | Publication date |
---|---|
EP2321248A4 (en) | 2012-01-11 |
US8624060B2 (en) | 2014-01-07 |
JP2010065034A (en) | 2010-03-25 |
CN102131759B (en) | 2013-12-11 |
CN102131759A (en) | 2011-07-20 |
JP5347851B2 (en) | 2013-11-20 |
US20110124915A1 (en) | 2011-05-26 |
EP2321248B1 (en) | 2013-11-06 |
EP2321248A1 (en) | 2011-05-18 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20050171381A1 (en) | Process for preparing fluorocarboxylic acids | |
KR101650694B1 (en) | Lactic acid extraction | |
US7253315B2 (en) | Process for preparing fluorocarboxylic acids | |
EP1385593A1 (en) | Process for obtaining an organic acid from an organic acid ammonium salt, an organic acid amide, or an alkylamine organic acid complex | |
KR100591625B1 (en) | Treatment of Formaldehyde-Containing Mixtures | |
US5352785A (en) | Continuous process for purifying perfluorochemical compositions | |
US8624060B2 (en) | Process for preparing fluorocarboxylic acid | |
JP2003012640A (en) | Process for producing percarboxylic acid | |
EP1679300B1 (en) | Process for producing polyglycerol fatty acid esters | |
EP0249648B1 (en) | Process for purifying allyl alcohol | |
US3906036A (en) | Reduction of chloride content in olefin derivatives such as vinyl acetate | |
EP0465294B1 (en) | Process for the preparation of unsaturated bromides | |
WO2021037672A1 (en) | A process for producing 4,4'-dichlorodiphenyl sulfone | |
CN113924282A (en) | Process for separating carboxylic acids from aqueous sidestreams |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200980132883.9 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 09811623 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 13055095 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2009811623 Country of ref document: EP |
|
NENP | Non-entry into the national phase |
Ref country code: DE |