JP2013521261A - Preparation of ethylenically unsaturated carboxylates by carboxylation of alkenes. - Google Patents

Abstract

The present invention relates to a method for producing an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid, and a) an alkene, carbon dioxide and a carboxylation catalyst are converted into an alkene / carbon dioxide / carboxylation catalyst. Converting to an adduct; b) decomposing the adduct with an auxiliary base to release a carboxylation catalyst to give an auxiliary base salt of an α, β-ethylenically unsaturated carboxylic acid; c) The α, β-ethylenically unsaturated carboxylic acid auxiliary base salt is reacted with an alkali metal base or alkaline earth metal base to release the auxiliary base, and the α, β-ethylenically unsaturated carboxylic acid alkali The present invention relates to a production method comprising a step of providing a metal salt or an alkaline earth metal salt. For example, the production of a water-absorbing resin requires a large amount of an α, β-ethylenically unsaturated carboxylic acid salt, particularly sodium acrylate.
[Selection figure] None

Description

  The present invention relates to a process for producing an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid by direct carboxylation of an alkene, in particular an alkali metal salt or alkali of acrylic acid by direct carboxylation of ethene. The present invention relates to a method for producing an earth metal salt.

The direct addition of CO ₂ to ethylene (Scheme 1) is due to thermodynamic limitations (AG = 34.5 kJ / mol) and is also unfavorable equilibration (almost completely on the reactant side at room temperature (K ₂₉₃ = 7 × 10 ^-7 )), so it is not industrially attractive.

Yamamoto et al., Reaction of acrylic acid with homogeneous Ni (0) species such as bis (1,5-cyclooctadiene) nickel in the presence of a tertiary phosphine compound ligand at temperatures above 0 ° C. Showed that a stable five-membered nickelalactone ring A known as “Hoberg complex” was obtained (Scheme 2) (J. Am. Chem. Soc. 1980, 102, 7448). At temperatures below 0 ° C., an equimolar mixture of lactone A and acyclic π complex B is obtained in the same reaction. Formation of free acrylic acid by thermal cleavage of A did not occur. A theoretical chemical study by Buntine et al. (Organometallics 2007, 26, 6784) showed that the stability of the intermediate nickelalactone A was increased by -40 kcal / mol ^-1 compared to the acrylic acid reaction product. ing.

As discovered by Hoberg (J. Organomet Chem. 1983, C51), the same nickel lactone A is formed by the direct coupling of CO ₂ and ethylene. Using a basic 2,2′-bipyridine ligand and Ni (0) species, the same reaction has been observed for other alkenes or alkynes (eg, norbornene) and cyclic nickel compounds derived therefrom. They can be isolated as stable solids (J. Organomet. Chem. 1982, C28), indicating that these compounds are extremely stable.

  In the case of the cyclic compound A, when such a stable nickelalactone is treated with a mineral acid aqueous solution, propionic acid is given and acrylic acid is not given. This indicates that the elimination of β hydride from complex A necessary for the production of acrylic acid and its derivatives is inhibited. Thus, no other catalyst for this reaction is known to date.

US2007 / 219391

The object of the present invention is to designate a method suitable for industrial production of α, β-ethylenically unsaturated carboxylic acid derivatives utilizing the reaction of CO ₂ with alkenes.

It became clear that the equilibrium of the reaction of CO ₂ and alkene can be shifted to the product side by using the auxiliary in the form of base. The formation of a salt of an α, β-ethylenically unsaturated carboxylic acid appears to be a thermodynamically favorable reaction. A salt of an α, β-ethylenically unsaturated carboxylic acid, particularly sodium acrylate, is demanded in large quantities, for example, in the production of a water absorbent resin (referred to as a super water absorbent resin).

The present invention is a method for producing an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid,
a) Converting alkene, carbon dioxide and carboxylation catalyst into alkene / carbon dioxide / carboxylation catalyst adduct,
b) The adduct is decomposed with an auxiliary base to liberate a carboxylation catalyst to form an auxiliary base salt of an α, β-ethylenically unsaturated carboxylic acid,
c) The α, β-ethylenically unsaturated carboxylic acid auxiliary base salt is reacted with an alkali metal base or alkaline earth metal base to liberate the auxiliary base, and the α, β-ethylenically unsaturated carboxylic acid Provided is a production method characterized by providing an alkali metal salt or an alkaline earth metal salt.

  Steps a) and b) of the process according to the invention can be carried out sequentially, but simultaneously in the presence of an auxiliary base in the carboxylation reactor by contacting the alkene, carbon dioxide and the carboxylation catalyst. Is preferred.

  The “alkene / carbon dioxide / carboxylation catalyst adduct” should be interpreted in a broad sense, and includes a compound having a structure similar to the “Hoberg complex” described at the beginning or a compound of unknown structure. The term includes isolatable compounds and labile intermediates.

  Suitable alkenes have at least 2 carbon atoms, such as 2-8 carbon atoms, or 2-6 carbon atoms, and at least one ethylenically unsaturated double bond. This double bond is preferably in the terminal position. The alkene may be a diene, in which case at least one carbon-carbon double bond is terminated and the other double bond is somewhere in the carbon skeleton. Suitable alkenes are, for example, ethene, propene, isobutene, piperylene. Alkenes used for carboxylation are usually gaseous or liquid under carboxylation conditions.

  In one preferred embodiment, the alkene is ethene. By the method of the present invention, a concentrated aqueous solution of an alkali metal salt or alkaline earth metal salt of allylic acid, particularly sodium acrylate, can be obtained with high purity and high yield. In another embodiment, potassium sorbate can be obtained, for example, from piperylene and KOH by the method of the present invention.

  Carbon dioxide used in this reaction can be used in a gaseous, liquid or supercritical state. Carbon dioxide-containing gas mixtures available on an industrial scale can also be used if they are substantially free of carbon monoxide.

  Carbon dioxide and alkene may contain an inert gas such as nitrogen or a noble gas. However, the content is preferably less than 10 mol% with respect to the total amount of carbon dioxide and alkene in the reactor.

  The molar ratio of carbon dioxide and alkene in the reactor feed is usually 0.1 to 10, preferably 0.5 to 3.

  The auxiliary base may be an organic auxiliary base or an inorganic auxiliary base. Suitable auxiliary bases are anionic bases (generally in the form of salts with inorganic or organic ammonium ions or alkali metals or alkaline earth metals) or neutral bases. Inorganic anionic bases include carbonates, phosphates, nitrates, or halides. Examples of organic anionic bases include phenoxide, carboxylate, organic molecular sulfate, sulfonate, phosphate, and phosphonate.

  Organic neutral bases include primary amines, secondary amines or tertiary amines, as well as ethers, esters, imines, amides, carbonyl compounds, carboxylates or carbon monoxide.

This auxiliary base is preferably a primary amine, a secondary amine or a tertiary amine. Most preferably, the auxiliary base is a tertiary amine. Suitable tertiary amines have the general formula (I):
NR ¹ R ² R ³ (I),

In the formula, the R ^{1 to} R ³ groups may be the same or different and are each independently unbranched or branched, acyclic or cyclic, aliphatic, araliphatic or aromatic. Each having 1 to 16 carbon atoms, preferably 1 to 12 carbon atoms, each of which is independently a hetero selected from the group -O- and> N- It may be substituted with atoms, and two groups or all three groups may be bonded together to form a chain containing at least 4 atoms each.

Examples of suitable amines include:
-Tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri- n-decylamine, tri-n-undecylamine, tri-n-dodecylamine, tri-n-tridecylamine, tri-n-tetradecylamine, tri-n-pentadecylamine, tri-n-hexadecylamine , Tri (2-ethylhexyl) amine
-Dimethyldecylamine, dimethyldodecylamine, dimethyltetradecylamine, ethyldi (2-propyl) amine, dioctylmethylamine, dihexylmethylamine
-Tricyclopentylamine, tricyclohexylamine, tricycloheptylamine, tricyclooctylamine, one or more of these: methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl or 2-methyl-2 -Derivatives substituted with propyl groups
-Dimethylcyclohexylamine, methyldicyclohexylamine, diethylcyclohexylamine, ethyldicyclohexylamine, dimethylcyclopentylamine, methyldicyclopentylamine
-Triphenylamine, methyldiphenylamine, ethyldiphenylamine, propyldiphenylamine, butyldiphenylamine, 2-ethylhexyldiphenylamine, dimethylphenylamine, diethylphenylamine, dipropylphenylamine, dibutylphenylamine, bis- (2-ethylhexyl) phenylamine, tribendi Substituted with one or more methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl or 2-methyl-2-propyl groups. Derivatives
_{- N-C 1 -~-C} 12 - alkyl piperidine, N, N'-di -C ₁ -~-C ₁₂ - alkyl piperazine _{s, N-C 1 -~-} C 12 - alkyl pyrrolidine, N-C ₁ -~-C ₁₂ - alkyl imidazole, also these, one or more methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, substituted derivatives of 2-butyl or 2-methyl-2-propyl group
-1,8-diazabicyclo [5.4.0] undes-7-ene (DBU), 1,4-diazabicyclo [2.2.2] octane (DABCO), N-methyl-8-azabicyclo [3.2 .1] Octane (tropane), N-methyl-9-azabicyclo [3.3.1] nonane (grantan), 1-azabicyclo [2.2.2] octane (quinuclidine).

  Of course, in the process of the invention, it is also possible to use mixtures of different bases, in particular mixtures of different tertiary amines (I).

It is preferable that at least one of R ^{1 to} R ³ groups has two hydrogen atoms on the α-carbon atom.

The tertiary amine used in the process of the present invention is most preferably an amine of the general formula (I), wherein the R ^{1 to} R ³ groups are each independently C _1- to C ₁₂ -alkyl and C _5- ˜C ₈ -cycloalkyl, selected from the group consisting of benzyl and phenyl.

  The amount of auxiliary base, preferably tertiary amine, used in the process of the invention is generally from 5 to 95% by weight, preferably from 20 to 60% by weight, based on the total liquid reaction mixture in the reactor. It is.

  In general, this carboxylation catalyst has at least one group 4 element (preferably Ti, Zr), group 6 element (preferably Cr, Mo, W), group 7 as an active metal. It contains an element (preferably Re), a group 8 element (preferably Fe, Ru), a group 9 element (preferably Co, Rh), and a group 10 element (preferably Ni, Pd). Nickel and cobalt, iron, rhodium, ruthenium, palladium, rhenium and tungsten are preferred. Nickel and cobalt, iron, rhodium and ruthenium are particularly preferred.

The role of these active metals, the CO ₂ and alkene activated, is to form a C-C bond between the CO ₂ and alkene. This activation is performed at one or more active points. After the formation of this “Hoberg” -like complex, it can be removed as an auxiliary base salt of an α, β-ethylenically unsaturated carboxylic acid in the presence of the auxiliary base used in the present invention.

  In some embodiments, the carboxylation catalyst used is a heterogeneous catalyst. The heterogeneous carboxylation catalyst may be present in the form of a supported catalyst or in the form of a non-supported catalyst. The supported catalyst includes a catalyst support, one or more active metals, and, if necessary, one or more additives.

  The weight ratio of active metal to the total amount of active metal, support material and additives is preferably 0.01 to 40% by weight, more preferably 0.1 to 30% by weight, most preferably 0.5 to 10%. % By weight.

  The weight ratio of additive to the total amount of active metal, support material and additive is preferably 0.001 to 20% by weight, more preferably 0.01 to 10% by weight, most preferably 0.1 to 5%. % By weight.

  Typical supported catalyst manufacturing methods include impregnation processes such as the incipient wetness method, adsorption processes such as equilibrium adsorption, precipitation processes, mechanical processes such as polishing of active metal precursors and support materials, and other industries. This is a process known to those skilled in the art.

  Suitable inorganic additives include magnesium, calcium, strontium, barium, lanthanum, lanthanoid, manganese, copper, silver, zinc, boron, aluminum, silicon, tin, lead, phosphorus, antimony, bismuth, sulfur, selenium . Suitable organic additives include carboxylic acids, salts of carboxylic acids, polymers such as PVP (polyvinyl pyrrolidone), PEG (polyethylene glycol), PVA (polyvinyl alcohol), amines, diamines, triamines, imines.

  Suitable support materials include zinc oxide, zirconium oxide, cerium oxide, cerium zirconium oxide, silica, alumina, silica-alumina, zeolite, layered silicate, hydrotalcite, magnesium oxide, titanium dioxide, tungsten oxide, oxidation Refractory oxides such as calcium, iron oxide (eg magnetite), nickel oxide, cobalt oxide, phosphates of typical and transition group elements, carbides, nitrides, organic polymers such as Nafion or functionalized polystyrene, metal sheets Or a metal support material such as a mesh, MOF (metal organic framework material) or a composite of the above materials.

  Zinc oxide, zirconium oxide, cerium oxide, cerium oxide, silica, alumina, silica-alumina, zeolite, layered silicate, hydrotalcite, magnesium oxide, titanium dioxide, tungsten oxide, calcium oxide, magnetite and other iron oxides, Refractory oxides such as nickel oxide or cobalt oxide are preferred.

  These support materials can be used, for example, in the form of powders, granules, tablets, or other forms known to those skilled in the art.

  In the present invention, a non-supported catalyst can also be used. These materials can be made, for example, by precipitation processes or other processes known to those skilled in the art. These catalysts are preferably present in the form of metal and / or oxide.

  If a heterogeneous catalyst is used in the process of the present invention, it is preferred that this catalyst remains in the carboxylation reactor. This catalyst is present, for example, in the form of a fixed bed catalyst fixed in the reactor, or in the case of a suspension catalyst, it remains retained in the reactor by means of a suitable sieve or a suitable filter.

  In a preferred embodiment, the carboxylation catalyst used is a homogeneous catalyst. The homogeneous catalyst is generally a metal complex. In the case of a homogeneous catalyst, the active metal is present in the reaction mixture in a homogeneous form in the form of a complex compound.

  Suitably the homogeneous carboxylation catalyst has at least one phosphine ligand. These phosphine ligands may be monodentate, bidentate or multidentate, i.e. the ligand is one, two or more, e.g. three tertiary. It may have a trivalent phosphorus atom. These phosphorus atoms may be unbranched or branched, acyclic or cyclic aliphatic groups having 1 to 18 carbon atoms.

Suitable monodentate phosphine ligands have, for example, formula (II).
PR ⁴ R ⁵ R ⁶ (II)

In the formula, R ⁴ , R ⁵ and R ⁶ are each independently C ₁ -C ₁₂ -alkyl, C ₃ -C ₁₂ -cycloalkyl, aryl, aryl-C ₁ -C ₄ -alkyl. Note that the aryl group of cycloalkyl and aryl or aryl-C ₁ -C ₄ -alkyl may be one, two, three or four identical or different substituents (eg, Cl, Br, I, F, C ₁ -C ₈ -alkyl or C ₁ -C ₄ -alkoxy).

Suitable R ⁴ , R ⁵ and R ⁶ groups are, for example, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 1- (2-methyl) propyl, 2- (2-methyl ) Propyl, 1-pentyl, 1- (2-methyl) pentyl, 1-hexyl, 1- (2-ethyl) hexyl, 1-heptyl, 1- (2-propyl) heptyl, 1-octyl, 1-nonyl, C ₁ -C ₁₂ -alkyl groups such as 1-decyl, 1-undecyl, 1-dodecyl; unsubstituted or C ₁ -C ₄ -alkyl groups (eg cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl) may have a norbornyl) C ₃ -C ₁₀ - cycloalkyl radical; an unsubstituted or chlorine and C ₁ -C ₈ - alkyl, C ₁ -C ₈ - selected from alkoxy It is one or two may have a substituent aryl group (e.g., phenyl or naphthyl, tolyl, xylyl, chlorophenyl or anisyl).

Examples of suitable phosphine ligands of formula (II) include trialkyl phosphines such as tri-n-propylphosphine, tri-n-butylphosphine, tri-tert-butylphosphine or trioctylphosphine, and tricyclohexylphosphine. Or tricycloalkylphosphine such as tricyclododecylphosphine, triphenylphosphine, tolylylphosphine, trianisylphosphine, trinaphthylphosphine or triarylphosphine such as di (chlorophenyl) phenylphosphine, diethylphenylphosphine or dibutylphenylphosphine And dialkylarylphosphine. R ⁴ , R ⁵ and R ⁶ are preferably as defined.

Suitable bidentate phosphine ligands have, for example, formula (III).
R ⁷ R ⁸ PA-PR ⁹ R ¹⁰ (III)

In which A is C ₁ -C ₄ -alkylene and R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently the same as defined for R ⁴ , R ⁵ and R ^6. .

  Examples of bidentate phosphines include 1,2-bis (dicyclohexylphosphino) ethane, 1,2-bis (dicyclohexylphosphino) methane, 1,2-bis (dimethylphosphino) ethane, and 1,2-bis. (Dimethylphosphino) methane, 1,2-bis (di-tert-butylphosphino) methane or 1,2-bis (diisopropylphosphino) propane.

  The organometallic complex may contain one or more, for example 2, 3 or 4 phosphine groups having at least one unbranched or branched, acyclic or cyclic aliphatic group as described above. Good.

  Also, at least one equivalent of the auxiliary base may function as a ligand on the metal of the homogeneous complex.

  Alternatively, the carboxylation catalyst may have at least one N-heterocyclic carbene ligand. Note that the N-heterocyclic carbene of the general formula (IV) or (V) functions as a ligand on the metal:

In the formula, R ¹¹ and R ¹² are each alkyl or aryl, and R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ are each independently hydrogen, alkyl or aryl, or R ^{13 to} R ¹⁶ groups. Each form a saturated 5- to 7-membered ring, the other two groups are each independently hydrogen or methyl, and R ¹⁷ and R ¹⁸ are each independently hydrogen, alkyl or aryl, R ¹⁷ and R ¹⁸ are fused rings having one or two aromatic rings with the carbon atom bonded to them.

In addition to the ligands described above, this catalyst can be used for halides, amines, carboxylates, acetylacetonates, aryl- or alkylsulfonates, hydrides, CO, olefins, dienes, cycloolefins, nitriles, aromatic and heteroaromatics. It may have ether, PF ₃ , phosphole, phosphabenzene and at least one other ligand selected from monodentate, bidentate and multidentate phosphinites, phosphonites, phosphoramidites and phosphite ligands.

These homogeneous catalysts can be obtained directly in active form, or standard complexes conventionally used, such as [M (p-cymene) Cl ₂ ] ₂ , [M (benzene) Cl ₂ ] _n. , [M (COD) (allyl)], [MCl ₃ × H ₂ O], [M (acetylacetonate) ₃ ], or [M (DMSO) ₄ Cl ₂ ] (where M is the periodic table) It can also be obtained by adding a corresponding ligand only under the reaction conditions from the elements of Group 4, 6, 7, 8, 9 or 10.

  When a homogeneous catalyst is used, the amount of the metal complex used in the organometallic complex is generally 0.1 to 5000 ppm by weight, preferably 1 to 5000 ppm based on the total liquid reaction mixture in the reactor. 800 ppm by weight, more preferably 5 to 500 ppm by weight.

  The carboxylation reactors used are in principle all reactors suitable for carrying out a gas-liquid reaction or a liquid-liquid reaction at a specific temperature and a specific pressure. Standard reactors suitable for liquid-liquid reaction systems are described, for example, in K.K. D. Henkel, “Reactor type and its industrial use”, Ullmann Industrial Chemistry Dictionary 2005, Wiley VCH Verlag GmbH & Co KGaA, DOI: 10.1002 / 143356007. b04 — 087, Chapter 3.3, “Reactor for gas-liquid reaction”. Examples thereof include a stirred tank reactor, a tubular reactor, and a bubble column reactor.

  This carboxylation may be carried out batchwise or continuously. If batchwise, the reactor is charged with the desired liquid feed or, if necessary, solid feed and auxiliaries, and then carbon dioxide and alkene are injected to the desired pressure and temperature. After the reaction is complete, the reactor is usually depressurized.

  When performed continuously, the feedstock and the auxiliary comprising carbon dioxide and alkene are added continuously. Any heterogeneous carboxylation catalyst used is preferably present in a fixed state in the reactor. Thus, the liquid phase is continuously removed from the reactor and the liquid level in the reactor is kept constant on average.

  Steps a) and b) are preferably carried out in the liquid phase or in a supercritical phase with a pressure of 1 to 150 bar, preferably a pressure of 1 to 100 bar, more preferably a pressure of 1 to 60 bar. Steps a) and b) of the method of the present invention are preferably performed at a temperature of -20 ° C to 300 ° C, preferably at a temperature of 20 ° C to 250 ° C, more preferably at a temperature of 40 ° C to 200 ° C.

  An appropriate apparatus can be used to mix the reactants with the medium containing the carboxylation catalyst and the auxiliary base. Such a device is equipped with one or more stirrers, with or without a baffle plate, even with a packed bubble column or unfilled bubble column, with or without a static mixer It may be a tube or unfilled flow tube, or other useful device known to those skilled in the art suitable for these processing steps. The use of baffles and delay structures is clearly included in the method of the present invention.

The reaction medium may be supplied with both CO ₂ and the alkene reactant, or may be supplied separated spatially. Such spatial separation can be achieved, for example, by simply providing two or more separate supply ports in a stirring tank. If more than one tank is used, different media may be supplied, for example, in different tanks. In the method of the present invention, CO ₂ and the alkene reactant can be added separately in time. Such temporal separation is performed, for example, by separately supplying the reactants into the stirring tank. If a flow tube or similar device is used, such feeding can be performed at different locations in the flow tube, for example. Such a change in addition position is a clever method of adding the reactants as a function of residence time.

  In steps a) and b) one or more immiscible liquid phases or poorly miscible liquid phases can be used. The use of supercritical media and ionic liquids and the establishment of conditions that promote the formation of such states are clearly included in the method. The use of phase transfer catalysts and / or the use of surfactants is clearly included in the process of the present invention.

  In one preferred embodiment, the auxiliary base salt of the α, β-ethylenically unsaturated carboxylic acid produced in step b) is removed from the reaction medium. The removal of the auxiliary base salt is carried out by dividing the liquid into the first liquid phase in which the auxiliary base salt of α, β-ethylenically unsaturated carboxylic acid is concentrated and the second liquid phase in which the auxiliary base is concentrated. It is preferable to include liquid phase separation.

  If a homogeneous carboxylation catalyst is used, it is preferably chosen such that it is concentrated in the second liquid phase with the auxiliary base. Note that “concentration” means that the distribution coefficient P of the homogeneous catalyst is> 1. This distribution coefficient is preferably ≧ 10, more preferably ≧ 20.

  This homogeneous catalyst is usually selected in a simple test that experimentally determines the desired homogeneous catalyst partition coefficient under the planned process conditions.

This liquid-liquid phase separation is either immiscible or poorly miscible in the second liquid phase in which the auxiliary base salt of the α, β-ethylenically unsaturated carboxylic acid is well dissolved and the auxiliary base is concentrated. This is facilitated by the further use of certain polar solvents.
It is necessary to select the polar solvent or match it to the auxiliary base so that the polar solvent is present in concentrated form in the first liquid phase. Note that “concentration” means that the weight ratio of the polar solvent in the first liquid phase is> 50% with respect to the total amount of the polar solvent in both liquid phases. This weight ratio is preferably> 90%, more preferably> 95%, most preferably> 97%. This polar solvent is generally selected in a simple test that can experimentally measure the partitioning of the polar solvent in the two liquid phases under process conditions.

  The types of substances suitable as polar solvents are diols and their carboxylic esters, polyols and their carboxylic esters, sulfones, sulfoxides, linear or cyclic amides, and mixtures of the above types of substances.

  Examples of suitable diols and polyols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, dipropylene glycol 1,5-pentanediol, 1,6-hexanediol, and glycerol.

Examples of suitable sulfoxides include dialkyl sulfoxides, preferably C _1- to C ₆ -dialkyl sulfoxides, particularly dimethyl sulfoxide.

  Examples of suitable chain or cyclic amides include formamide, N-methylformamide, N, N'-dimethylformamide, N-methylpyrrolidone, acetamide, and N-methylcaprolactam.

  If necessary, it is possible to use an immiscible or poorly miscible solvent for this polar solvent. Suitable solvents are in principle (i) those which are chemically inert to the alkene carboxylation, (ii) auxiliary bases, and homogeneous catalysts dissolve well when using homogeneous catalysts. (Iii) those in which the base salt of an α, β-ethylenically unsaturated carboxylic acid is well dissolved, and (iv) those that are immiscible or poorly miscible in a polar solvent. Thus, in principle, useful solvents are chemically inert non-polar solvents, such as aliphatic, aromatic or araliphatic hydrocarbons, specifically octane, higher alkanes, toluene, xylene. If the auxiliary base itself is present in liquid form at all processing steps of the process of the invention, it is not necessary to use a solvent that is immiscible or poorly miscible with the polar solvent.

  When using a homogeneous carboxylation catalyst, for example, the carboxylation catalyst can be brought into the second liquid phase by successfully selecting an auxiliary base and, if necessary, a polar solvent and / or an immiscible or poorly miscible solvent. It can be concentrated. For example, the carboxylation catalyst can be separated from the auxiliary base salt of α, β-unsaturated acid by phase separation and further recycled to the reactor without a post-treatment step. Since the catalyst is quickly removed from the auxiliary base salt formed from the α, β-unsaturated acid, the reverse reaction accompanying decomposition into carbon dioxide and alkene is suppressed. Also, since two liquid phases are formed, catalyst retention or removal reduces catalyst loss, and thus reduces active metal loss. In order to remove the first liquid phase, a method of simply taking out the first liquid phase from the carboxylation reactor and leaving the second liquid phase in the carboxylation reactor may be employed. Alternatively, the liquid-liquid mixed stream can be withdrawn from the carboxylation reactor and the liquid-liquid phase separation can be carried out in a suitable apparatus outside the carboxylation reactor. These two liquid phases are generally separated by gravimetric phase separation. Examples suitable for this purpose are e.g. Muller et al. "Liquid-liquid extraction", Ullmann Industrial Chemical Dictionary, 2005, Wiley-VCH Verlag GmbH & Co. KGaA, DOI: 10.1002 / 14356007. Standard equipment and standard methods described in b03 — 06, Chapter 3, “Apparatus”. In general, the first liquid phase enriched with the auxiliary base salt of α, β-ethylenically unsaturated carboxylic acid is heavy and forms the lower phase. The second liquid phase can then be recycled to the carboxylation reactor.

  In step c), the auxiliary base salt of the α, β-ethylenically unsaturated carboxylic acid is reacted with an alkali metal base or alkaline earth metal base to release the auxiliary base, and α, β-ethylenic An alkali metal salt or an alkaline earth metal salt of an unsaturated carboxylic acid is provided. Suitable alkali metal bases or alkaline earth metal bases are in particular alkali metal or alkaline earth metal hydroxides, carbonates, bicarbonates or oxides. Suitable alkali metal and alkaline earth metal hydroxides are, for example, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide. Suitable alkali metal and alkaline earth metal carbonates are, for example, lithium carbonate, sodium carbonate, potassium carbonate, calcium carbonate. Suitable alkali metal bicarbonates are, for example, sodium bicarbonate or potassium bicarbonate. Suitable alkali metal and alkaline earth metal oxides are, for example, lithium oxide, sodium oxide, calcium oxide, and magnesium oxide. Sodium hydroxide is particularly preferred.

  This alkali metal or alkaline earth metal base is suitable for allowing base exchange between an auxiliary base salt of an α, β-ethylenically unsaturated carboxylic acid and an alkali metal or alkaline earth metal base. Added under various conditions. Step c) of the process according to the invention is preferably carried out in the liquid phase or in a supercritical phase at a pressure of 1 to 150 bar, preferably a pressure of 1 to 100 bar, more preferably 1 to 60 bar. Step c) of the method of the present invention is preferably carried out at a temperature of -20 ° C to 300 ° C, preferably at a temperature of 20 ° C to 250 ° C, more preferably at a temperature of 40 ° C to 200 ° C. The reaction conditions in step c) may be the same as or different from the reaction conditions in steps a) and b).

  In step c) one or more immiscible or poorly miscible liquid phases can be used. Usually, such immiscible or poorly miscible liquid phases are an organic phase and an aqueous phase. The use of supercritical media and ionic liquids and the establishment of conditions that facilitate the formation of such states are clearly included in the method.

  It is preferred to separate the alkali metal salt or alkaline earth metal salt of the α, β-ethylenically unsaturated carboxylic acid from the auxiliary base by separating them into two different phases. Thus, for example, an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid in a highly polar aqueous phase can be separated from an auxiliary base in the organic phase. The use of effects that aid in separation, such as the use of phase changes in ionic liquids or supercritical media, is clearly included in the method. Changes in pressure or temperature that positively affect phase separation are clearly included in the method.

  The auxiliary base released is recycled to step b). This recycling takes place under conditions suitable for the process.

  The first liquid phase to be removed is treated with an aqueous solution of an alkali metal base or an alkaline earth metal base, and an aqueous solution of an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid and an auxiliary base It is preferable to obtain an organic phase containing

  The first liquid phase is generally immiscible or poorly miscible with the alkali metal base or alkaline earth metal base solution, and the treatment is suitably performed in the form of a liquid-liquid extraction. Liquid-liquid extraction can be carried out in all devices suitable for this purpose, for example in stirred vessels, extractors or filters. An aqueous solution containing an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid and an organic phase containing an auxiliary base are obtained.

  The released auxiliary base is recycled to the carboxylation reactor. Due to the simple process design, a manufacturing plant that needs to implement the method of the present invention requires less space and uses fewer devices than the prior art. Capital cost is low and energy demand is small.

  In another embodiment, in step c), the reaction medium (in which the α, β-ethylenically unsaturated carboxylic acid auxiliary base salt has not been previously removed) is treated with an aqueous solution of an alkali metal base or alkaline earth metal base. To obtain an aqueous solution of an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid. The extraction can be carried out directly in the carboxylation reactor simultaneously with steps a) and b). For this purpose, an alkali metal base or alkaline earth metal base solution is introduced into the carboxylation reactor, the reaction medium is extracted with the alkali metal base or alkaline earth metal base solution in the carboxylation reactor, and α An aqueous solution of an alkali metal salt or alkaline earth metal salt of a β-ethylenically unsaturated carboxylic acid can be removed from the carboxylation reactor.

Claims (15)

A method for producing an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid, comprising:
a) converting the alkene, carbon dioxide and carboxylation catalyst into an alkene / carbon dioxide / carboxylation catalyst adduct;
b) decomposing the adduct with an auxiliary base to release a carboxylation catalyst to give an auxiliary base salt of an α, β-ethylenically unsaturated carboxylic acid;
c) The α, β-ethylenically unsaturated carboxylic acid auxiliary base salt is reacted with an alkali metal base or alkaline earth metal base to release the auxiliary base, and the α, β-ethylenically unsaturated carboxylic acid is released. A step of providing an alkali metal salt or an alkaline earth metal salt.   The process according to claim 1, wherein the auxiliary base salt of α, β-ethylenically unsaturated carboxylic acid formed in step b) is removed from the reaction medium.   Claim wherein the removal comprises a liquid-liquid phase separation into a first liquid phase enriched in an auxiliary base salt of an α, β-ethylenically unsaturated carboxylic acid and a second liquid phase enriched in an auxiliary base. Item 3. The method according to Item 2.   In step c), the removed first liquid phase is treated with an aqueous solution of an alkali metal base or alkaline earth metal base to obtain an alkali metal salt or alkaline earth of an α, β-ethylenically unsaturated carboxylic acid. The process according to claim 3, wherein an organic phase comprising an aqueous solution of a metal salt and an auxiliary base is obtained.   In step c), the reaction medium is extracted with an aqueous solution of an alkali metal base or alkaline earth metal base to obtain an aqueous solution of an alkali metal salt or alkaline earth metal salt of an α, β-ethylenically unsaturated carboxylic acid. The method of claim 1.   The method according to any one of claims 1 to 5, wherein the auxiliary base is a tertiary amine. The tertiary amine has the general formula (I):

NR ¹ R ² R ³ (I)

Wherein R ^{1 to} R ³ groups may be the same or different and are each independently unbranched or branched, acyclic or cyclic, aliphatic, araliphatic or aromatic. Each group having 1 to 16 carbon atoms, each of which may be independently substituted with a hetero group selected from the group -O- and> N-, The process according to claim 6, wherein two or all three groups may be bonded together to form a chain each containing at least 4 atoms.   The method according to any one of claims 1 to 7, wherein the carboxylation catalyst contains at least one element of Groups 4, 6, 7, 8, 9, and 10 of the Periodic Table of Elements. The method of claim 8, wherein the carboxylation catalyst comprises a Ni ⁰ complex.   The method according to claim 1, wherein the carboxylation catalyst used is a heterogeneous catalyst.   The method according to any one of claims 1 to 9, wherein the carboxylation catalyst used is a homogeneous catalyst.   The process according to any one of claims 3 to 9, wherein the carboxylation catalyst used is a homogeneous catalyst and the carboxylation catalyst is concentrated in the second liquid phase.   The method according to any one of claims 1 to 12, wherein the carboxylation catalyst comprises at least one phosphine ligand.   13. A process according to any one of claims 1 to 12, wherein the carboxylation catalyst comprises at least one N-heterocyclic carbene ligand.   The method according to claim 1, wherein the alkene is ethene and the α, β-ethylenically unsaturated carboxylic acid is acrylic acid.