Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/02—Preparation of carboxylic acids or their salts, halides or anhydrides from salts of carboxylic acids
• • 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
  • C07C51/487—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification
  • C07C51/493—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification whereby carboxylic acid esters are formed
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/48—Separation; Purification; Stabilisation; Use of additives
  • C07C67/58—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment

Definitions

• the present invention relates to a process for the treatment of fluorinated acid, in particular of fluorinated acetic acid, for example difluoroacetic acid (DFA) or trifluoroacetic acid (TFA), in particular a process for the treatment of fluorinated acid under salified form in an aqueous solution.
• fluorinated acid in particular of fluorinated acetic acid, for example difluoroacetic acid (DFA) or trifluoroacetic acid (TFA)
• DFA difluoroacetic acid
• TSA trifluoroacetic acid
• DFA can be produced by different processes and according to the process can be solubilized in an aqueous solution in the form of a salt, especially sodium salt. DFA, even after acidification, is soluble in aqueous solution; this makes its recovery, for example by distillation or extraction, very difficult.
• the object of the present invention is to provide a process for the treatment of fluorinated acid, in particular a process for treating a fluorinated acid salt in aqueous solution, in particular DFA or TFA.
• Another object of the present invention is to provide such a method which is simple to implement and which makes it possible to obtain a product that can be recovered in good yields and with high purity.
• the method of the present invention makes it possible to remedy the various problems mentioned above.
• the inventors have surprisingly discovered that it is possible to treat an aqueous solution containing a fluorinated acid salt soluble in aqueous phase, by esterification of this salt in acidic medium.
• the method of the invention also solves this technical problem.
• the present invention relates to a method for treating an aqueous solution comprising a salt of an organic compound comprising at least one acid function and at least one fluorine atom, said fluoro acid, by reaction between said salt and at least one Brönsted acid in the presence of an organic solvent solubilizing the product that is formed, said organic solvent forming at least one biphasic liquid / liquid reaction medium with the aqueous solution.
• the fluorinated acid is especially chosen from fluorinated carboxylic acids soluble in water.
• the acid is chosen from aliphatic carboxylic acids comprising at least one fluorine atom and comprising from 2 to 15 carbon atoms, preferably from 2 to 10 carbon atoms.
• aliphatic carboxylic acids comprising at least one fluorine atom and comprising from 2 to 15 carbon atoms, preferably from 2 to 10 carbon atoms.
• fluorinated acetic acids mention may be made.
• fluoroacetic acid is intended to denote mono-, di- and trifluoroacetic acids, and any of their mixtures, preferably di- and trifluoroacetic acids, more particularly the difluoroacetic acid.
• the aqueous solution comprising the fluorinated acid salt is an aqueous solution from a process for preparing said acid.
• the aqueous solution comprising the fluorinated acid salt is an effluent, the fluorinated acid then being a by-product to be upgraded.
• the counterion may in particular be chosen from the elements of columns 1 to 12 of the periodic table of the elements, preferably the counterion is an alkaline or an alkaline earth metal, for example sodium, potassium or lithium.
• the choice of the organic solvent among the abovementioned solvents is then carried out as a function of the density of the aqueous medium comprising the salt of the salified fluorinated acid.
• the term "at least one biphasic liquid / liquid reaction medium” denotes a medium comprising two liquid phases, on the one hand the organic solvent phase and, on the other hand, the aqueous phase, such a medium may also comprise suspended solid compounds. such as, for example, precipitated salts.
• the term "Brönsted acid” means a molecule capable of yielding one or more protons.
• a Brönsted acid according to the invention is chosen from strong acids whose pKa is less than 2, and in particular from HCl, H 2 SO 4 , HNO 3 , HBr or H 3 PO 4 , pure or diluted, or any of their mixtures.
• Hydrochloric acid can be used in gaseous form and / or in solution (aqueous solution).
• the acid is used in proportions of 1 to 5 molar equivalents, preferably 1 to 3 molar equivalents, relative to the salt of the fluorinated acid.
• the product formed from the reaction between the fluorinated acid salt and the Brönsted acid is solubilized by the organic solvent.
• the organic solvent can be used in any proportion; it is preferably used in proportions of 50 to 200%, preferably 50 to 100% by volume relative to the volume of the aqueous solution.
• the process of the invention can be carried out at a temperature of 10 to
• the method of the invention is implemented in batch. In another particular embodiment, the method of the invention is implemented continuously.
• a reactor provided with a stirring system that allows a strong stirring of the reaction medium, in particular a reactor equipped with a type 4 stirring system.
• blades in particular four inclined blades; turbine type, for example Rushton turbine.
• the process according to the invention may further comprise at least one step of separating the organic solvent / product mixture formed from the aqueous solution, in particular by decantation.
• the aqueous phase is recovered separately during this separation step.
• this aqueous phase can be subjected to a novel treatment method according to the invention for the purpose of converting the fluorinated acid salts that have not yet been transformed (several extraction stages).
• the recovered aqueous phase may optionally be subjected to one or more liquid / liquid extractions with the abovementioned solvents without additional addition of reagents (several extraction stages).
• the process of the invention may further comprise at least one step of distillation of the organic solvent / product mixture formed from the separation step.
• This distillation step can be implemented by any method known to those skilled in the art.
• the size (especially the diameter) of the distillation columns depends on the circulating flow and the internal pressure. Their sizing will therefore be mainly according to the mixing rate to be treated.
• all the distillations used in the process of the invention are carried out at atmospheric pressure.
• the distillation column may be advantageously, but not exclusively, a column having the following specifications: number of theoretical stages: from 3 to 30, preferably from 3 to 25;
• separation columns comprising from 2 to 50 theoretical stages, preferably from 2 to 30 theoretical stages, in particular columns of the type: packed columns; stationary or moving trays; rotating disk columns; columns with agitated compartments, such as, for example, Kuhni columns; the pulsed columns, for example the pulsed columns with perforated discs; or batch reactors as described above placed in series with an overflow system continuously allowing the passage from one reactor to another.
• This distillation step may be preceded by a flash distillation step to obtain a concentrated organic medium formed product.
• This flash distillation step is preferably carried out at atmospheric pressure, in a distillation column comprising less than 10 theoretical stages, a flow rate R less than 5.
• the method according to the invention is preferably implemented in installations resistant to corrosion of the reaction medium. It is thus possible to use alloys based on molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon and tungsten sold under the trademarks HASTELLOY® or alloys of nickel, chromium, iron, manganese additives of copper and / or molybdenum sold under the name INCONEL® and more particularly alloys HASTELLOY C 276 or INCONEL 600, 625 or 718. It is also possible to choose stainless steels, such as austenitic steels [Robert H.
• a steel having a nickel content of at most 22% by weight is used, preferably between 6 and 20%, and more preferably between 8 and 14%.
• 316 and 316 L steels have a nickel content ranging from 10 to 14%.
• the material may also be selected from graphite materials and fluorinated polymers, and their derivatives. Of the fluoropolymers, PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride) and PFA (perfluoroalkyl resins) are particularly suitable for carrying out the process of the invention. Finally, the material may be vitreous steel. The choice of material will depend on the reaction medium and salts it may contain, the skilled person is able to determine these materials with his general knowledge. Particularly preferred materials are vitreous steel and fluoropolymers.
• the organic solvent is chosen from solvents solubilizing the product formed but then allowing its separation for example by distillation.
• the organic solvent is chosen from solvents having a boiling point sufficiently far from the boiling point of the product formed to allow separation, in particular by distillation.
• the organic solvent used for the process of the invention may be a mixture of organic solvents.
• the organic solvent is chosen from apolar solvents.
• the organic solvent is chosen from aromatic solvents, halogenated aliphatic solvents, preferably chlorinated solvents, or alkyl ethers, preferably C 1 to C 15, preferably C 1 to C 10, alkyl ethers, or their mixtures.
• aromatic solvent denotes solvents having an aromatic ring, for example phenyl, optionally substituted with one or more groups, in particular chosen from linear or branched alkyl groups comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms. carbon atoms; halogen atoms, preferably chlorine; -Oalkyl groups with linear or branched alkyl comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms.
• the aromatic solvent is selected from xylene (ortho, meta or para), toluene, chlorobenzene, dichlorobenzene, mesithylene, methoxybenzene (anisole), 1,2-dimethoxybenzene (veratrole), ethylbenzene , trifluoromethylbenzene, or any of their mixtures.
• halogenated aliphatic is understood to mean a linear or branched alkyl chain comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, and being substituted by one or more halogen atoms, especially chlorine.
• the organic solvent is selected from dichloromethane, dichloroethane, chloroform, or any of their mixtures.
• alkyl ether denotes linear or branched alkyl ethers, preferably comprising from 2 to 15 carbon atoms, for example from 2 to 10 carbon atoms.
• the alkyl ether is chosen from methyltertiobutyl ether (MTBE) or diisobutylether, or their mixture.
• the process of the invention may further comprise reacting the fluorinated acid salt with Brönsted acid and an alcohol to produce the corresponding ester.
• the products formed by the process of the invention are especially fluorinated acid or the ester of the fluorinated acid.
• the invention relates to a method of treating an aqueous solution comprising a fluorinated acid salt by reaction between said salt and a Brönsted acid in the presence of an organic solvent solubilizing the acid which is form, said organic solvent forming at least one biphasic liquid / liquid reaction medium with the aqueous solution.
• the organic solvent is chosen from aromatic solvents, in particular substituted by one or more -Oalkyl groups with linear or branched alkyl comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms; or the alkyl ethers.
• the solvent is methoxybenzene (anisole), 1,2-dimethoxybenzene (veratrole), MTBE or diisobutyl ether. This embodiment can advantageously be implemented from fluorinated acetic acid salt, and especially from DFA salt.
• the invention relates to a method of treating an aqueous solution comprising a fluorinated acid salt by reaction between said salt, a Brönsted acid and an alcohol in the presence of an organic solvent solubilizing the ester which is formed, said organic solvent forming at least one biphasic liquid / liquid reaction medium with the aqueous solution.
• the fluorinated acid salt is as defined above. This embodiment is particularly well suited to the fluorinated aliphatic carboxylic acid salts as defined above and in particular to the salts of fluorinated acetic acids and more particularly to the salts of DFA.
• Such a process makes it possible surprisingly to obtain good conversion efficiencies of the fluorinated acid salt and good yields in terms of ester production of this acid.
• the process of the invention makes it possible to obtain a fluorinated acid ester of purity greater than 90%, preferably greater than 95%, more preferably close to 99%.
• the conversion efficiency of the fluorinated acid salt by the process of the invention is greater than 80% and preferably greater than 90%.
• the yield of fluorinated acid ester is greater than 80% and preferably greater than 90%.
• the process of the invention relates to a process for treating DFA salt and obtaining a DFA ester. All the variants and embodiments apply in particular to the DFA.
• the alcohol according to the invention is a water-soluble alcohol having a low molecular weight.
• the alcohol according to the invention is an alcohol of formula R 1 OH in which R 1 represents a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, for example methyl, ethyl, propyl, isopropyl, butyl, pentyl and isopentyl.
• the alcohol is chosen from methanol, ethanol and isopropanol, the ester formed is then the ethyl, methyl or isopropyl ester of difluoroacetic acid.
• the alcohol is ethanol.
• the organic solvent is chosen from solvents solubilizing the ester formed but then allowing its separation by distillation.
• the organic solvent is chosen from solvents having a boiling point sufficiently far from the boiling point of the ester of the fluorinated acetic acid formed to allow a separation of the organic solvent and the ester, especially by distillation.
• the organic solvent is chosen from organic solvents having a boiling point of less than or equal to 90 ° C., preferably from 30 to 90 ° C. ° C or a boiling point greater than or equal to 100 ° C, preferably 100 to 200 ° C, for example from 1 to 180 ° C, measured at atmospheric pressure (101325 Pa).
• the organic solvent used for the reaction may be a mixture of solvents.
• the ester formed is the ethyl ester of fluorinated acetic acid and the organic solvent is chosen from the solvents solubilizing this ester.
• the organic solvent is chosen from apolar solvents.
• the different conditions described in the context of the process of the invention can be combined with each other.
• the solvent is chosen from aromatic solvents or chlorinated aliphatic solvents.
• the organic solvent may be chosen from aromatic solvents having a boiling point greater than or equal to 100 ° C., preferably from 100 to 200 ° C. for example from 1 to 180 ° C.
• the aromatic solvents defined above can be used.
• the organic solvent is selected from xylene (ortho, meta or para), toluene, chlorobenzene, dichlorobenzene, mesithylene, methoxybenzene (anisole), 1,2-dimethoxybenzene (veratrole), ethylbenzene , trifluoromethylbenzene, or any of their mixtures.
• the organic solvent may be chosen from halogenated aliphatic solvents having a boiling point less than or equal to 90 ° C., preferably from 30 to 90 ° C. vs.
• the halogenated aliphatics are in particular defined above.
• the organic solvent is selected from dichloromethane, dichloroethane, chloroform, or any of their mixtures.
• the organic solvent may be selected from C2 to C15, preferably C2 to C10, alkyl ethers.
• the process according to the invention may also comprise at least one step of separating the organic solvent / acid ester mixture formed from the aqueous solution, in particular by decantation. .
• the aqueous phase is recovered separately during this separation step.
• this aqueous phase can be subjected to a novel treatment method according to the invention for the purpose of converting the fluorinated acetic acid salts which have not yet been converted (several extraction stages).
• the recovered aqueous phase may optionally be subjected to one or more liquid / liquid extractions with the abovementioned solvents without additional addition of alcohol (several extraction stages).
• the process of the invention may further comprise at least one step of recovering the ester of the fluorinated acid by distillation of the organic solvent / acid ester mixture. fluorinated from the separation step.
• This distillation step can be implemented by any method known to those skilled in the art and in particular according to the variants and embodiments described above.
• the fraction whose boiling point is between 97 and 99 ° C. is recovered during this distillation, it corresponds to the fraction of the ester of the fluorinated acid having a purity greater than 90%, preferably greater than 95%, more preferably close to 99%.
• the organic solvent fraction obtained at the top of the column in the case of an organic solvent having a boiling point of less than 90 ° C., or obtained at the bottom of the column in the case of an organic solvent exhibiting a boiling temperature above 100 ° C, can be recycled to the esterification step of the process of the invention.
• the fractions containing the insufficiently pure fluorinated acid ester and the alcohol may be recycled to the esterification step of the process of the invention.
• This distillation step may be preceded by a flash distillation step to obtain a concentrated organic medium ester of fluorinated acetic acid.
• This flash distillation step is preferably carried out at atmospheric pressure, in a distillation column comprising less than 10 theoretical stages, a flow rate R less than 5.
• the invention relates to a process for preparing an ester from a fluorinated acid implementing the method of the invention.
• the present invention therefore also relates to a method for preparing a fluorinated acid ester comprising treating an aqueous solution comprising a salt of an organic compound comprising at least one acid function and at least one fluorine atom, said fluorinated acid, by reaction between said salt, an alcohol and at least one Brönsted acid in the presence of an organic solvent solubilizing the product that is formed, said organic solvent forming at least one biphasic liquid / liquid reaction medium with the aqueous solution.
• the embodiments and preferred modes described above also apply to the process for preparing the fluorinated acid ester.
• the temperature is expressed in degrees Celsius and is the ambient temperature (20-25 ° C) unless stated otherwise.
• the pressure is atmospheric unless otherwise indicated.
• Rushton is added 574.7 g of an aqueous solution containing 14.4% by weight of sodium difluoroacetate and 9% by weight of sodium chloride as well as 126 g of concentrated sulfuric acid at 98% by weight. Sulfuric acid is added in 1 hour so as to keep the temperature below 50 ° C. After returning to ambient temperature, 207 g of xylene (o-, m-, p- isomer mixture) and 39.7 g of ethanol are added. The medium is stirred at 850 rpm for one hour at room temperature. The stirring is then stopped and the upper organic phase is recovered by decantation. Two additional liquid liquid extraction operations are carried out from the aqueous solution obtained, with the addition of twice 207 g of xylenes.

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• 2012
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• 2013
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