Catalytic process for preparing α,β-ethylenically unsaturated carboxylic acid salt

Abstract

To provide a process for preparing an α,β-ethylenically unsaturated carboxylic acid salt that is not subject to restrictions with regard to usable reaction solvents.SOLUTION: A catalytic process for preparing an α,β-ethylenically unsaturated carboxylic acid salt comprises: a) contacting an alkene and carbon dioxide with a carboxylation catalyst, an organic solvent, and an alkoxide having a secondary or tertiary carbon atom directly bound to an [O-] group, to obtain a crude reaction product comprising the α,β-ethylenically unsaturated carboxylic acid salt and an alcohol by-product which is the conjugate acid of the alkoxide; b) allowing the α,β-ethylenically unsaturated carboxylic acid salt to precipitate out from the crude reaction product; and c) subjecting at least part of the crude reaction product to a mechanical separation step while maintaining the alcohol by-product in liquid form to obtain a solid phase comprising the α,β-ethylenically unsaturated carboxylic acid salt and a liquid phase comprising the carboxylation catalyst, the organic solvent and the alcohol by-product.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a catalytic process for preparing α,β-ethylenically unsaturated carboxylate salts, in which an alkene and carbon dioxide are contacted with a catalyst, an organic solvent, and an alkoxide. The unsaturated carboxylate salts are obtained as solids, which are mechanically separated from the reaction mixture and the alcohol by-product. [Background technology]

[0002] The direct addition of carbon dioxide onto alkenes to give α,β-ethylenically unsaturated carboxylates, e.g., onto ethene to give acrylates, is of major industrial interest due to the high availability and low cost of the reactants. Research to overcome the unfavorable thermodynamic limitations and unfavorable equilibria, which at room temperature are virtually entirely on the side of the reactants, has led to several catalytic methods in recent years.

[0003] WO 2016 / 180775 A1 describes a method for obtaining a first liquid phase enriched in α,β-ethylenically unsaturated carboxylic acid salts and a second liquid phase enriched in carboxylation catalyst by contacting a crude reaction product from the reaction of an alkene and CO in the presence of a carboxylation catalyst and an alkoxide with a polar solvent, such as water. The alcohol by-product is distilled off from the first liquid phase. This method achieves catalyst turnover in a single stage while allowing separation of the carboxylic acid salts from the alcohol by-product. This known method imposes limitations on the reaction solvents that can be used, for example, because only solvents with limited miscibility with water can be used. Furthermore, the second liquid phase enriched in carboxylation catalyst is separated from the aqueous phase enriched in α,β-ethylenically unsaturated carboxylic acid salts, and the second liquid phase contains trace amounts of water, which tends to deactivate the carboxylation catalyst. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 180775A1 [Non-patent literature]

[0005] [Non-Patent Document 1] KD Henkel, “Reactor Types and Their Industrial Application”, Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley VCH Verlag GmbH & Co KGaA, DOI: 10.1002 / 14356007.b04_087, chapter 3.3 “Reactors for gas-liquid reactions” Summary of the Invention [Problem to be solved by the invention]

[0006] The problem underlying the present invention can be seen as providing a process for preparing α,β-ethylenically unsaturated carboxylic acid salts that is not subject to the above limitations. [Means for solving the problem]

[0007] The problem is solved by a catalytic method for preparing an α,β-ethylenically unsaturated carboxylic acid salt, comprising: a) An alkene and carbon dioxide are reacted with a carboxylation catalyst, an organic solvent, and [O - ] group to obtain a crude reaction product comprising an α,β-ethylenically unsaturated carboxylic acid salt and an alcohol by-product which is the conjugate acid of the alkoxide; b) precipitating the α,β-ethylenically unsaturated carboxylic acid salt from the crude reaction product; and c) subjecting at least a portion of the crude reaction product to a mechanical separation step, while maintaining the alcohol by-product in liquid form, to obtain a solid phase comprising the α,β ethylenically unsaturated carboxylic acid salt and a liquid phase comprising the carboxylation catalyst, the organic solvent, and the alcohol by-product. The problem is solved by providing a catalytic method comprising: DETAILED DESCRIPTION OF THE INVENTION

[0008] Due to its ionic nature, the α,β-ethylenically unsaturated carboxylic acid salt has limited solubility in most organic solvents and precipitates from the crude reaction product. It has been found that this process can be controlled in a way that allows other components of the reaction mixture, particularly the alcohol by-product, to remain liquid and / or dissolved, thereby allowing the α,β-ethylenically unsaturated carboxylic acid salt to be easily separated by mechanical separation operations.

[0009] By subjecting the crude reaction product to a mechanical separation step while maintaining the alcohol by-product in liquid form, it is possible to obtain a precipitated α,β-ethylenically unsaturated carboxylic acid salt in a high-purity solid phase. The mechanical separation step advantageously does not require the use of additional chemicals, such as polar solvents, or the separation of immiscible liquid phases. For example, the present method does not require the use of water, which advantageously reduces the number of by-products.

[0010] The solution behavior of the carboxylate salt and alcohol by-product can be controlled by the choice of organic solvent and / or process temperature. Advantageously, the alcohol by-product is essentially completely soluble in the organic solvent within the temperature range of process steps a) to c).

[0011] Suitable alkenes are those of the general formula:

[0012] [ka]

[0013] (In the formula, R x, R y and R z are each independently hydrogen, C 1~12 -Alkyl, C 2~12 -alkenyl, or R x and R y together with the carbon atoms to which they are attached, are monoethylenically or diethylenically unsaturated 5- to 8-membered carbocyclic rings. is an alkene.

[0014] Suitable alkenes include ethene, propene, isobutene, butadiene, piperylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 2-butene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclooctadiene, or styrene. The alkenes used in the process according to the invention are generally gaseous or liquid under the reaction conditions.

[0015] In step a), the partial pressure of the alkene is, for example, in the range of from 0.5 bar to 200 bar, preferably from 1 bar to 100 bar, in particular from 2 bar to 80 bar, more preferably from 3 bar to 60 bar, and most preferably from 5 to 50 bar. All pressures indicated herein are absolute pressures.

[0016] In a preferred embodiment, the alkene is ethene. In this embodiment, the α,β-ethylenically unsaturated carboxylic acid salt obtained by the process of the present invention is an acrylate salt.

[0017] In another embodiment, the alkene is piperylene. In this embodiment, the α,β-ethylenically unsaturated carboxylic acid salt obtained by the process of the present invention is a sorbate salt.

[0018] The carbon dioxide for use in step a) of the process according to the invention may be used in gaseous, liquid or supercritical form. It is also possible to use CO2-containing gas mixtures available on an industrial scale, provided that they are substantially free of carbon monoxide.

[0019] The CO2 and alkene may also contain inert gases, such as nitrogen or noble gases, but advantageously the content thereof is less than 10 mol% relative to the total amount of carbon dioxide and alkene in the process.

[0020] The molar ratio of CO2 to alkene in step a) is generally in the range of 0.1 to 10, preferably in the range of 0.5 to 5. CO2 and alkene are generally fed to step a) in a molar ratio of CO2 to 1 mole of alkene in the range of 0.1 to 10, preferably in the range of 0.5 to 5 moles.

[0021] The partial pressure of carbon dioxide in step a) is preferably maintained above 1 bar. It is, for example, maintained at least 2 bar, in particular at least 4 bar, and most preferably at least 6 bar. The partial pressure of carbon dioxide in step a) is preferably maintained below 200 bar. It is, for example, maintained at a maximum of 160 bar, in particular at a maximum of 140 bar, and most preferably at a maximum of 120 bar. In step a) of the method according to the invention, the partial pressure of carbon dioxide is preferably maintained in the range of 1 to 200 bar, preferably 2 to 160 bar, in particular 4 to 140 bar, more preferably 6 to 120 bar, and most preferably 10 to 100 bar.

[0022] The choice of organic solvent, along with the choice of temperature in step c) of the process, can be important for precipitating the carboxylate salt while maintaining the alcohol by-product in liquid form.

[0023] Due to their ionic nature, α,β-ethylenically unsaturated carboxylic acid salts have limited solubility in most organic solvents over a wide range of temperatures. Typically, the alcohol by-product precipitates from the organic solvent at a lower temperature than the α,β-ethylenically unsaturated carboxylic acid salt or is essentially completely soluble within the temperature range of the process step.

[0024] The organic solvent is preferably an aprotic solvent.Aprotic means that the solvent molecule does not contain hydrogen atoms bonded to heteroatoms, such as hydrogen atoms bonded to nitrogen atoms or hydrogen atoms bonded to oxygen atoms.This is advantageous because the absence of hydrogen atoms bonded to heteroatoms tends to suppress undesired side reactions.Most preferably, all hydrogen atoms contained in the organic solvent molecule are bonded to carbon atoms.

[0025] The organic solvent of the present invention may be an amide or a urea, or may contain at least one amide and at least one urea moiety. It may be a monomer or a linear or cyclic oligomer, such as a dimer, trimer, or tetramer, containing multiple, e.g., two, three, or four, amide or urea subunits. The term "amide" refers to carboxamides and sulfonamides, with carboxamides being preferred. The term "urea" refers to carbamides and sulfamides, with carbamide being the preferred urea.

[0026] Preferably, the amide, e.g., carboxamide, or urea, e.g., carbamide, is linear or cyclic and contains at least 3 carbon atoms, e.g., 3 to 20 carbon atoms, preferably 3 to 18 carbon atoms, and most preferably 3 to 16 carbon atoms, with all carbon atoms other than the carbonyl carbon atom saturated and no hydrogen atom bonded to a nitrogen.

[0027] The organic solvent is an amide, such as formamide (there is no hydrogen atom attached to the nitrogen atom and all carbon atoms in the amide group are saturated except for the carbonyl carbon atom, which has the general formula C a H b N1O1 (In the formula, a is an integer of 3 to 20, for example, 3 to 18, preferably 3 to 16, and b is an integer of 2a-5 to 2a+1.) Even if or urea (there are no hydrogen atoms attached to the nitrogen atoms and all carbon atoms except the carbonyl carbon atom in the amide group are saturated, which has the general formula C c H d N2O1 (In the formula, c is an integer of 5 to 20, for example, 6 to 18, preferably 7 to 16, and d is an integer of 2c-4 to 2c+2.) (having

[0028] Suitable organic solvents include N,N-disubstituted formamides, N,N-disubstituted acetamides, N-substituted 2-pyrrolidones, or 1,3-disubstituted 2-imidazolidinones, or mixtures thereof. The substituents are preferably independently linear or branched C1-C 16 -alkyl and C3-C9-cycloalkyl. In the case of N,N-disubstituted compounds, the two substituents may together form a cyclic moiety, for example a C3-C9-cycloalkyl or a C3-C9-heterocycloalkyl, which may be partially unsaturated or saturated.

[0029] Examples of N,N-disubstituted formamides include N,N-dialkylformamides, such as N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-dipropylformamide, N,N-dibutylformamide, N,N-dipentylformamide, N,N-dihexylformamide, N-formylmorpholine, N-formylpiperidine, N-methyl-N'-ethylformamide, N-methyl-N'-propylformamide, N-methyl-N'-butylformamide, N-methyl-N'-pentylformamide, N-methyl-N'-hexylformamide, N-ethyl-N'-propylformamide, N-ethyl-N'-butylformamide, N-ethyl-N'-pentylformamide, N-ethyl-N'-hexylformamide, N-propyl-N'-butylformamide, N-propyl-N'-pentylformamide, N-propyl-N'-hexylformamide, N-butyl-N'-pentylformamide, N-butyl-N'-hexylformamide, and N-pentyl-N'-hexylformamide Examples include:

[0030] Examples of N,N-disubstituted acetamides include N,N-dibutylacetamide and N,N-dihexylacetamide.

[0031] Examples of N-substituted 2-pyrrolidones include N-methylpyrrolidone, N-ethylpyrrolidone, N-decylpyrrolidone, and N-cyclohexylpyrrolidone.

[0032] An example of a 1,3-disubstituted 2-imidazolidinone is 1,3-dimethyl-2-imidazolidinone.

[0033] In these organic solvents, the alkyl moieties may independently be linear or branched, for example, "propyl" may independently be n-propyl or isopropyl, and "butyl" may independently be n-butyl, sec-butyl, isobutyl, or tert-butyl.

[0034] N,N-dimethylformamide, N,N-dibutylformamide, and N-formylmorpholine are particularly preferred organic solvents. The most preferred organic solvent is N,N-dimethylformamide (DMF).

[0035] In another embodiment, the organic solvent can include a co-solvent, such as a polar, high-boiling co-solvent. The co-solvent can help maintain the solubility of the catalyst system during work-up. The co-solvent can be a glycol or glycol derivative, or a mixture of such a compound with any of the compounds described above as suitable. Suitable organic co-solvents include glycols, glycol derivatives, and mixtures thereof. Examples of glycols include ethylene glycol (EG) and propylene glycol. Examples of glycol derivatives include polyalkylene glycols, such as diethylene glycol (DEG) and triethylene glycol (TEG), di- or mono(C1-C4-alkyl ether) glycols, such as ethylene glycol monomethyl or dimethyl ether, and di- or mono(C1-C4-alkyl ether) polyalkylene glycols, such as diethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, and triethylene glycol dimethyl ether. Preferred glycol derivatives are end-capping compounds that do not have free hydroxy groups, such as di(C1-C4-alkyl ether) glycols, such as dimethyl ether, and di(C1-C4-alkyl ether) polyalkylene glycols, such as diethylene glycol dimethyl ether and triethylene glycol dimethyl ether.

[0036] In step a) of the method of the present invention, [O - Alkoxides having a secondary or tertiary carbon atom directly bonded to a ] group are converted to an alcohol by-product, which is the conjugate acid of the alkoxide. The alkoxide is preferably at least partially soluble in an organic solvent. The alkoxide is consumed stoichiometrically.

[0037] The alkoxide used in this method is [O - [O] groups. Any undesired direct reaction of alkoxides with CO, particularly the undesired formation of half esters, can be prevented by the use of [O] groups. -It is speculated that inhibition is more efficient when the residue attached to the ] group is sterically bulky.

[0038] " [O - The term "alkoxide having a secondary or tertiary carbon atom directly bonded to a ] group" refers to an alkoxide of the general formula (I) - OR (I) (wherein R is a hydrocarbyl residue containing a carbon atom bonded to an oxygen atom of general formula (I), and the carbon atom bonded to the oxygen atom of general formula (I) is a secondary carbon atom or a tertiary carbon atom). A secondary carbon atom is understood to mean a carbon atom directly bonded to an oxygen atom of general formula (I) having two carbon-carbon bonds and a carbon-hydrogen bond. A tertiary carbon atom is understood to mean a carbon atom directly bonded to an oxygen atom of general formula (I) having three carbon-carbon bonds.

[0039] Tertiary groups are generally sterically bulkier than secondary groups. - The alkoxides having a secondary or tertiary carbon atom directly bonded to the [O - ] group ("tertiary alkoxide").

[0040] The hydrocarbyl residue R may be acyclic, cyclic, or contain a cyclic moiety. R is preferably acyclic. The hydrocarbyl residue R may be saturated or unsaturated. Saturated hydrocarbyl residues R contain only single bonds, while unsaturated hydrocarbyl residues R contain at least one double bond. The hydrocarbyl residue R is preferably saturated.

[0041] Any hydrogen atom of R may be replaced by one or more non-interfering substituents. Non-interfering substituents are those that are inert under the conditions of the process according to the invention, i.e., do not react with compounds or intermediates that are in contact with the alkoxide or the conjugate acid of the alkoxide in the process according to the invention. Suitable substituents include -F, -Cl, and -O-C1-C6-alkyl. R is preferably unsubstituted, which means that R consists only of carbon and hydrogen atoms.

[0042] The alkoxides can be derived from alcohols having multiple hydroxy groups, i.e., polyols, e.g., diols such as ethylene glycol, diethylene glycol, propanediol, or butanediol. - The term "alkoxide having a secondary or tertiary carbon atom directly bonded to a [O] group" refers to an alkoxide having a secondary or tertiary carbon atom directly bonded to a [O] group. - ] group is understood to mean that a secondary or tertiary carbon atom is directly attached.

[0043] In a preferred method, the alkoxide is derived from an alcohol that does not decompose when distilled. Therefore, the alkoxide can be selected based on the decomposition temperature of its conjugate acid, i.e., the conjugate alcohol. Generally, the decomposition temperature of the conjugate alcohol is preferably significantly higher than its boiling temperature at 1 bar. The decomposition temperature of the conjugate acid, i.e., the conjugate alcohol, of the alkoxide is preferably at least 10° C., particularly at least 20° C., e.g., 30° C. to 200° C., higher than its boiling temperature at 1 bar. The boiling temperature at 1 bar is preferably not too high to provide an energetically favorable process.

[0044] This difference between the decomposition temperature and the boiling temperature can be established by selecting an alkoxide based on the molecular weight of its conjugate acid, i.e., the conjugate alcohol. Low molecular weight compounds tend to have low boiling temperatures. The molecular weight of the conjugate acid of the alkoxide is, for example, in the range of 55 to 200 g / mol, preferably 70 to 180 g / mol, particularly 95 to 180 g / mol, and most preferably 100 to 160 g / mol.

[0045] In one embodiment, the boiling point of the conjugate acid, i.e., the conjugate alcohol, of the alkoxide is preferably between the boiling points of methanol and the organic solvent, while in another embodiment, the boiling point of the conjugate acid, i.e., the conjugate alcohol, of the alkoxide is preferably higher than the boiling points of both the organic solvent and methanol.

[0046] In a preferred embodiment, the difference between the boiling point of the organic solvent and the boiling point of the conjugate alcohol at 1 bar absolute pressure is at least 5°C, preferably at least 8°C, most preferably at least 25°C.

[0047] In a preferred method, [O - The alkoxide having a secondary or tertiary carbon atom directly bonded to the alkoxide group has the following general formula (II): - OCR 1 (R 2 )2 (II) (In the formula, R 1 is H or R 2 and Each R 2 are independent, C1~C 10 -hydrocarbyl, or two or three R 2 together with the secondary or tertiary carbon atoms to which they are attached, form one or more 3- to 8-membered carbocyclic rings. Contains the subunits:

[0048] Each R 2 For example, independently, C1 to C 10 -Alkyl, C3-C 10-Cycloalkyl and C6-C 10 -aryl. Preferably, each R 2 are independently selected from C1-C6 alkyl.

[0049] Preferably, [O - Alkoxides having a secondary or tertiary carbon atom directly bonded to the ] group are - O-tert-butyl, - O-isopropyl, - O-sec-butyl, - O-cyclopropyl, and - O-((1-methyl)-cyclopropyl), - O-cyclohexyl, and - O-((1-methyl)-cyclohexyl)).

[0050] Preferably, the alkoxide is acyclic and is [O - ] group. - Alkoxides having a secondary or tertiary carbon atom directly bonded to the [O alkoxides] group are selected, for example, from alkali metal alkoxides and alkaline earth metal alkoxides. Alkali metal alkoxides and especially sodium alkoxides, especially [O alkoxides] - Sodium alkoxides having a tertiary carbon atom directly bonded to the ] group are preferred.

[0051] [O - Particularly preferred alkoxides having a secondary or tertiary carbon atom directly bonded to [O - The most preferred alkoxides having a secondary or tertiary carbon atom directly bonded to the alkoxide contain 5 to 10 carbon atoms.

[0052] [O - Examples of preferred sodium alkoxides having a secondary or tertiary carbon atom directly bonded to Sodium isopropoxide (sodium propan-2-olate), sodium tert-butoxide, sodium cyclopentanolate, sodium cyclohexanolate, sodium cycloheptanolate, sodium butan-2-oleate, sodium 3-methylbutan-2-olate, sodium 4-methylpentan-2-olate, sodium pentane-3-oleate, sodium 1-methoxypropan-2-olate, sodium 1-methylcyclopentan-1-olate, sodium 1-methylcyclohexane-1-olate, sodium 2-phenylpropan-2-olate, sodium 3-methylheptan-3-olate, sodium 3-methylhexan-3-olate, sodium 2-methylhexan-2-olate, sodium 2-methylbutan-2-olate, sodium 3-ethylpentan-3-olate, sodium 2-methylpentan-2-olate, sodium 3-methylpentan-3-oleate, Sodium 3,7-dimethyloctan-3-olate, and Sodium 2,3-dimethyl-2-butanolate Examples include:

[0053] Sodium tert-butoxide, sodium 3-methylpentan-3-olate, sodium 3-ethylpentan-3-olate, and sodium 3,7-dimethyloctane-3-olate, especially sodium 3-methylpentan-3-olate, sodium 3-ethylpentan-3-olate, and sodium 3,7-dimethyloctane-3-olate, are particularly preferred alkoxides.

[0054] The alkoxide may be added, for example, in solid form, as a neat liquid (liquid without additives) (if the alkoxide is in liquid form at room temperature), or as a solution.

[0055] The method includes contacting an alkene and carbon dioxide with a carboxylation catalyst, which is preferably a transition metal complex.

[0056] In step a), the carboxylation catalyst is preferably present in an amount of from 0.1 to 20,000 ppm by weight, preferably from 1 to 1,000 ppm by weight, in particular from 5 to 500 ppm by weight, of transition metal relative to the total weight of the reaction mixture.

[0057] The term "transition metal complex" as used herein includes in a general manner all transition metal complexes through which the catalytic cycle is envisaged, i.e., transition metal-alkene complexes, metallalactones and adducts in which an α,β-ethylenically unsaturated carboxylic acid salt is coordinated to the transition metal.

[0058] Generally, the transition metal complex contains at least one element from Group 4 (preferably Ti, Zr), Group 6 (preferably Cr, Mo, W), Group 7 (preferably Re), Group 8 (preferably Fe, Ru), Group 9 (preferably Co, Rh), and Group 10 (preferably Ni, Pd, Pt) of the Periodic Table as the active metal. Nickel and palladium are preferred. Most preferably, the transition metal complex is a palladium complex.

[0059] The role of the active metal is to activate CO2 and an alkene to form a C-C bond between CO2 and the alkene. Metallalactones are presumed to be formed from an alkene, carbon dioxide, and a transition metal complex during the catalytic cycle. The term "metallalactone" refers to a lactone in which a carbon atom has been exchanged for a metal atom (γ-lactone), according to the exchange nomenclature ("one" nomenclature). The term "metallalactone" should be interpreted broadly and may include compounds with a structure similar to the Hoberg complex or related compounds of oligomeric or polymeric structure. This term includes isolable compounds and (unstable) intermediates.

[0060] Metallalactones can be described by the following general formula:

[0061] [ka]

[0062] During the ceremony, M is a transition metal; L is a ligand, m is 1 or 2, and R a , R b , and R c are each independently hydrogen, C 1~12 -Alkyl, C 2~12 -alkenyl, or R a and R b together with the carbon atoms to which they are attached are saturated or mono- or diethylenically unsaturated 5- to 8-membered carbocyclic rings.

[0063] The alkoxide is presumed to deprotonate the metallalactone at the carbon atom alpha to the carbonyl group.

[0064] Preferably, the transition metal complex comprises a ligand coordinated to the transition metal through at least one coordination atom selected from P, N, O, and C. The ligand preferably comprises at least one phosphorus atom coordinated to the transition metal. The ligand may be monodentate or polydentate, for example, bidentate. Generally, two monodentate ligands or one bidentate ligand coordinate to the transition metal.

[0065] Polydentate, e.g., bidentate, ligands can coordinate to a transition metal to form a 4-, 5-, 6-, 7-, or 8-membered ring, i.e., the transition metal, the atom coordinating to the transition metal, and the atoms in the shortest chain connecting the atoms coordinating to the transition metal together form a 4-, 5-, 6-, 7-, or 8-membered ring. Ligands that coordinate to a transition metal, e.g., nickel or palladium, to form a 5-, 6-, or 7-membered ring are preferred.

[0066] Alternatively, the atom coordinating to the transition metal may be bonded directly to carbon atoms of two cyclopentadienyl ligands bonded to a second metal, for example, iron.

[0067] At least one residue is preferably bonded to the phosphorus atom coordinated to the transition metal via a secondary or tertiary carbon atom. More particularly, at least two residues are preferably bonded to the phosphorus atom via a secondary or tertiary carbon atom. Preferred residues bonded to the phosphorus atom via a secondary or tertiary carbon atom are adamantyl, tert-butyl, sec-butyl, isopropyl, cyclohexyl, and cyclopentyl.

[0068] The ligand is preferably a bidentate P,X ligand (X is selected from P, N, O, and carbene), in particular a bidentate P,P ligand. The P and X atoms are separated by a divalent linker (linking group) containing, for example, 2 to 4 bridging atoms. The linker is preferably linked to the P atom by a single bond, to the X atom by a single bond, and contains 2 to 4 bridging atoms linked by single bonds.

[0069] The bidentate P,X ligand, especially the bidentate P,P ligand, may be structurally constrained or unconstrained. It is preferably structurally unconstrained.

[0070] In conformationally constrained bidentate P,X ligands, particularly bidentate P,P ligands, the bridging atoms may be part of at least one cyclic substructure, particularly at least one 5- to 7-membered cyclic substructure. In preferred bidentate P,P ligands in which the bridging atoms are part of at least one 5- to 7-membered cyclic substructure, each bridging atom directly connected to the P atom, together with the P atom to which it is connected, is part of a 5- to 7-membered cyclic substructure, or two adjacent bridging atoms are part of a 5- to 7-membered cyclic substructure.

[0071] A preferred structurally constrained bidentate P,P ligand is of formula (IIIa):

[0072] [ka]

[0073] During the ceremony, R 3 independently, CHR 4 2. CR 4 3. C3~C 10 -cycloalkyl and optionally alkylated aryl having 6 to 18 carbon atoms; R 4 are independently selected from C1-C4-alkyl, preferably linear C1-C4-alkyl, A 1 forms, together with the carbon atom to which it is attached and the intervening phosphorus atom, a 5- to 7-membered cyclic moiety; and R 5 are independently hydrogen, C1 to C 12 -Alkyl, C3-C 12 -Cycloalkyl, C3-C 12 -heterocycloalkyl, C6-C 14 -Aryl, C6-C 14 -heteroaryl, C1-C12 -Alkoxy, C3-C 12 -Cycloalkoxy, C3-C 12 -heterocycloalkoxy, C6-C 14 -aryloxy and C6-C 14 -heteroaryloxy.

[0074] A 1 is preferably -(CR 5’ 2) j -and-(CR 6 =CR 6 ) k - Selected from both R 6 are on the same side of the double bond, and R 5’ are independently selected from H, C1-C3-alkyl, and —O—C1-C3-alkyl; R 6 is selected from H and C1-C3-alkyl, or at least two R 6 forms a bridge of one of the following formulas:

[0075] [ka]

[0076] j is 2 or 3, and k is 1 or 2.

[0077] R 3 is preferably independently CHR 4 2. CR 4 3, and C3-C8-cycloalkyl, most preferably CR 4 It is 3.

[0078] R 4 is preferably methyl.

[0079] R 5 is preferably H.

[0080] A 1is preferably ethylene, ethenylene, 1,2-phenylene, 1,2-naphthylene, 2,3-naphthylene, and the following formula:

[0081] [ka]

[0082] is selected from.

[0083] A preferred structurally constrained bidentate P,P ligand is of formula (IIIb):

[0084] [ka]

[0085] During the ceremony, R 7 are independently selected from linear C1-C4 alkyl; R 8 independently, CHR 7 2. CR 7 3. C3~C 10 -cycloalkyl and optionally alkylated aryl having 6 to 18 carbon atoms; X is independently selected from CH, C—CH, and N; and A 2 together with the moiety X to which it is attached and the intervening carbon atoms form a 5- to 7-membered cyclic moiety.

[0086] R 7 are preferably independently selected from C1-C6-alkyl and C3-C7-cycloalkyl, and R 8 is CR 10 It is 3.

[0087] R 7 may, for example, be independently selected from linear C1-C4-alkyl, in particular linear C1-C2-alkyl.

[0088] R8 is preferably independently CHR 7 2. CR 7 3, and C3-C8-cycloalkyl.

[0089] A 2 is preferably a -CH=CH- bridge.

[0090] X is preferably CH.

[0091] A preferred structurally constrained bidentate P,P ligand is of formula (IIIc):

[0092] [ka]

[0093] During the ceremony, R 9 and R 10 are independently, C3~C 10 -cycloalkyl, for example C5-C7-cycloalkyl, and R 11 is H, O—C1-C6-alkyl, or both R 11 together form a -CH=CH- bridge.

[0094] R 11 is preferably H or OCH3, most preferably H.

[0095] In preferred structurally unconstrained bidentate P,X ligands, e.g., bidentate P,P ligands, each of the bridging atoms is unbranched and none of the bridging atoms is part of any cyclic substructure apart from the ring containing the transition metal.

[0096] In particularly preferred bidentate P,P ligands, each of the bridging atoms is unbranched, and none of the bridging atoms is part of any cyclic substructure apart from the transition metal-containing ring. In particularly preferred bidentate P,P ligands, the P atoms are separated by a linker comprising two bridging carbon atoms, and each P atom is connected by a single bond to the linker and to two secondary carbon-bonded residues, the bridging carbon atoms being connected by single bonds. The expression "secondary carbon-bonded residue" refers to a residue that is bonded to the P atom via a secondary carbon atom contained in the residue. Each of the four secondary carbon-bonded residues may be the same or different, and is preferably a secondary C3-C4 20 - Hydrocarbyl residue (secondary C3-C 20 -any hydrogen atom contained in the hydrocarbyl residue may be replaced by one or more non-interfering substituents. Non-interfering substituents are those which are inert under the conditions of the process according to the invention, i.e. which do not react with any compound or intermediate which is in contact with the ligand in the process according to the invention. Suitable non-interfering substituents include, for example, O-C1-C6-alkyl. Secondary C3-C 20 The hydrocarbyl residues are preferably unsubstituted, which means that they consist only of hydrogen and carbon atoms. Preferred unsubstituted secondary C-C 20 -hydrocarbyl residues are 2-propyl, 2-butyl, 2-pentyl, 3-pentyl, cyclopentyl, cyclohexyl, and cycloheptyl. A preferred linker is -CH2-CH2-.

[0097] A preferred structurally unconstrained bidentate P,P ligand is of formula (IIId): R 12 R 13 P-(CR 14 R 15 ) e-PR 12 R 13 (IIId) (In the formula, R 12 and R 13are independently unbranched or branched, acyclic or cyclic, aliphatic residues having 1 to 20 carbon atoms, each carbon atom being optionally replaced by a hetero group selected from -O- and >N- groups, each hydrogen atom being optionally replaced by Cl or F, and any two residues bonded to the same phosphorus atom being optionally covalently bonded to each other; e is 1, 2, 3, 4, or 5, preferably 2, 3, or 4; R 14 are independently H, C1-C8-alkyl, C1-C8-alkoxy, C3-C 10 -Cycloalkyl, C3-C 10 -Cycloalkoxy, C6-C 10 -aryl and C6-C 10 -aryloxy, or two vicinal R 14 the residues, together with the carbon atoms to which they are attached, form a 5- to 7-membered carbocyclic ring which may be aromatic, partially unsaturated, or saturated, and R 15 are independently H, C1-C8 alkyl, C3-C 10 -Cycloalkyl and C6-C 10 -aryl.

[0098] Preferably, (CR 14 R 15 ) e is -CH2-CH2-, -CH2-CH2-CH2-, or -CH2-CH2-CH2-CH2-.

[0099] R 12 and R 13 are preferably independently C1 to C 20 -Alkyl or C3-C 20 -cycloalkyl, where C1-C 20 -alkyl is unsubstituted or substituted with 1, 2, 3, or 4 substituents independently selected from Cl, F, and C1-C4-alkoxy; 20-Cycloalkyl is unsubstituted or substituted with 1, 2, 3, or 4 substituents independently selected from Cl, F, C1-C8-alkyl, and C1-C4-alkoxy.

[0100] R 12 and R 13 are most preferably independently methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, tert-butyl, 1-(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, 1-decyl, 1-undecyl, 1-dodecyl, adamantyl, cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl, or norbornyl, in particular independently 2-propyl, 2-butyl, tert-butyl, adamantyl, cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl, or norbornyl.

[0101] A particularly preferred bidentate P,P ligand is a ligand of the following formula (IIId-1): R 12 R 13 P-(CR 14 H)e-PR 12 R 13 (IIId-1) (In the formula, R 12 and R 13 are each independently an unbranched or branched, acyclic or cyclic, aliphatic residue having 1 to 20 carbon atoms; e is 2, 3, or 4, and R 14 are independently H, C1-C8-alkyl, C1-C8-alkoxy, C3-C 10 -Cycloalkyl, C3-C 10 -Cycloalkoxy, C6-C 10 Aryl and C6-C 10-aryloxy, or two vicinal R 14 The residues, together with the carbon atoms to which they are attached, form a 5- to 7-membered carbocyclic ring which may be aromatic, partially unsaturated, or saturated. 14 is H.

[0102] In a particularly preferred process according to the invention, the ligand is selected from the group consisting of 1,2-bis(dicyclohexylphosphino)ethane, 1,3-bis(dicyclohexylphosphino)propane, 1,4-bis(dicyclohexylphosphino)butane, 2,3-bis(dicyclohexylphosphino)butane, 1,2-bis(dicyclopentylphosphino)ethane, 1,3-bis(dicyclopentylphosphino)propane, 1,4-bis(dicyclopentylphosphino)butane, 1,2-bis(dicycloheptylphosphino)ethane, 1,3-bis(dicycloheptylphosphino)propane, 1,4-bis(dicycloheptylphosphino)butane, 1,2-bis(diisopropylphosphino)ethane, 1,3-bis(diisopropylphosphino)propane, 1,4-bis(diisopropylphosphino)butane, 1,2-bis(di-sec-butylphosphino)ethane, 1,3-bis(di-sec-butylphosphino)propane, 1,4-bis(di-sec-butylphosphino)butane, 1,2-bis(dodecylphosphino)ethane, 1,3-bis(dodecylphosphino)propane, 1,4-bis(dodecylphosphino)butane, 1,2-bis(decylphosphino)ethane, 1,3-bis(decylphosphino)propane, 1,4-bis(decylphosphino)butane, 1,2-bis(tetradecylphosphino)ethane, 1,3-bis(tetradecylphosphino)propane, 1,4 -bis(tetradecylphosphino)butane, 1,2-bis(hexadecylphosphino)ethane, 1,3-bis(hexadecylphosphino)propane, 1,4-bis(hexadecylphosphino)butane, 1,2-bis(di-tert-butylphosphino)ethane, 1,3-bis(di-tert-butylphosphino)propane, 1,4-bis(di-tert-butylphosphino)butane, 1,2-bis(dicyclohexylphosphino)cyclohexane and

[0103] [ka]

[0104] from, Preferred are 1,2-bis(dicyclohexylphosphino)ethane, 2,3-bis(dicyclohexylphosphino)butane, 1,2-bis(diisopropylphosphino)ethane, 1,2-bis(dodecylphosphino)ethane, 1,2-bis(di-tert-butylphosphino)ethane, 1,2-bis(dicyclopentylphosphino)ethane, 1,2-bis(dicyclohexylphosphino)cyclohexane, and

[0105] [ka]

[0106] is selected from.

[0107] Suitable ligands are, for example, bidentate and polydentate ligands containing one or two coordinated phosphorus atoms and an additional carbon atom or heteroatom bonded to the transition metal. Preferably, when an additional carbon atom or heteroatom is bonded to the transition metal, a five-membered ring is formed, such as, for example, (diphenylphosphino)acetate, known from the SHOP process, or 2-(dimethylphosphino)-N,N-dimethylethanamine. A specific bidentate ligand is the ligand of formula (IIIg):

[0108] [ka]

[0109] During the ceremony, W is phosphorus (P) or phosphite (P=O); R 16are independently an unbranched or branched, acyclic or cyclic, aliphatic, araliphatic, or aromatic residue having 1 to 16 carbon atoms, each carbon atom being optionally replaced by a hetero group selected from -O- and >N- groups, and each hydrogen atom being optionally replaced by Cl or F; R 17 and R 18 are independently an unbranched or branched, acyclic or cyclic, aliphatic, araliphatic, or aromatic residue having 1 to 16 carbon atoms, wherein each carbon atom is independently optionally replaced by a hetero group selected from -O- and >N- groups, and each hydrogen atom is independently optionally replaced by Cl, Br, I, or F, and both residues are optionally covalently bonded to each other; R 19 and R 20 are together a chemical bond, or R 17 and R 18 as defined for R 21 and R 22 is R 17 and R 18 as defined for R 23 and R 24 is R 17 and R 18 is as defined for

[0110] Preferably, R 17 , R 18 , R 19 , and R 20 are independently hydrogen, C1 to C 12 -Alkyl or C1-C 14 -aryl; or R 17 and R 18 are independently hydrogen, C1 to C 12 -Alkyl or C1-C 14 -aryl, and R 19 and R 20 are together a chemical bond; or R 17 and R 18are independently hydrogen or methyl, and R 19 and R 20 together, C3~C 10 -Alkane-1,3-diyl, C3-C 10 -Alkane-1,4-diyl or C3-C 10 -alkane-1,3-diyl bridge; or R 19 and R 20 together form a chemical bond, and R 17 and R 18 together with the carbon atoms to which they are attached are part of a monocyclic or bicyclic aromatic ring system.

[0111] R 16 , R 21 , and R 22 are preferably independently C1 to C 12 -Alkyl, C3-C 12 -cycloalkyl or C3-C 14 -aryl, where C3-C 12 -Cycloalkyl and C3-C 14 -Aryl is unsubstituted or substituted with 1, 2, 3, or 4 substituents independently selected from Cl, F, C1-C8-alkyl, and C1-C4-alkoxy.

[0112] R 16 , R 21 , and R 22 are most preferably independently methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, tert-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, 1-decyl, 1-undecyl, 1-dodecyl, adamantyl, cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl, norbornyl, phenyl, naphthyl, tolyl, xylyl, chlorophenyl, or anisyl.

[0113] The ligand may also be a bidentate or polydentate ligand containing one or two coordinating nitrogen atoms and an additional carbon atom bonded to the transition metal. Preferably, when the additional carbon atom is bonded to the transition metal, a five-membered ring is formed, such as, for example, 2-phenylpyridine or 6-phenyl-2,2'-bipyridine.

[0114] Suitable tridentate ligands are, for example, ligands of formula (IIIh) below: R 12 R 13 P-(CR 14 R 15 ) f -PR 12 -(CR 14 R 15 ) g -PR 12 R 13 (IIIh) (In the formula, R 12 , R 13 , R 14 , and R 15 are each as previously defined, and f and g are independently 1, 2, 3, 4, or 5, preferably 2, 3, or 4.

[0115] Exemplary tridentate ligands are ((methylphosphinediyl)bis-(methylene))bis(dimethylphosphine), ((ethylphosphinediyl)bis(methylene))bis(diethyl-phosphine), and ((methylphosphinediyl)bis(methylene))bis(diphenylphosphine).

[0116] In addition to the ligands mentioned above, the transition metal complexes may also have at least one additional ligand selected from alkoxides, alcohol by-products that are the conjugate acids of alkoxides, halides, amines, amides, oxides, phosphides, carboxylates, acetylacetonates, aryl or alkyl sulfonates, hydrides, CO, olefins, dienes, cycloolefins, nitriles, aromatic and heteroaromatic, ethers, PF3, phosphoryl, and monodentate, bidentate, and polydentate phosphinite, phosphonite, phosphoramidite, and phosphite ligands.

[0117] Any of these additional ligands are displaced when the alkene and carbon dioxide are reacted.

[0118] A transition metal complex, e.g., a palladium or nickel complex, can be obtained, for example, from a ligand and a transition metal, e.g., palladium or nickel, or from a transition metal source, e.g., a palladium or nickel source, comprising a ligand and a transition metal, e.g., palladium or nickel, in the oxidation state 0. Alternatively, the transition metal complex can be obtained, for example, by reducing a salt of the transition metal with a reducing agent, e.g., H, Mg, Na, or Zn.

[0119] Examples of palladium sources include PdL2, PdL4, LPdX2, L2PdX2, L2Pd2X2, LPd2X4, Pd3X6, L3Pd2, L2Pd2, (In the formula, X is selected from halide, pseudohalide, carboxylate, alkoxide, carbonate, sulfate, nitrate, hydroxide, acetylacetonate, cyclopentadiene, alkyl, and aryl; and L is a neutral ligand selected from phosphines, amines, olefins, carbonyls, and nitriles. and the corresponding adducts with solvents such as ether, DMSO, or water.

[0120] Palladium sources and salts are preferably [Pd2(allyl)2(Cl)2], [Pd2(methallyl)2(Cl)2], [Pd(dba)2], [Pd2(dba)3], PdCl2, PdBr2, PdI2, Pd(NO3)2, PdSO4, [Pd(OAc)2], [Pd(PtBu3)2], [Pd(PCy3)2], [Pd(Polyl3)2], [Pd(PPh3)4], [Pd(COD)(Cl)(Me)], [Pd(Phen)(OAc)2], [Pd 2(PtBu3)2(Br)2], [Pd(C6H5CN)2(Cl)2], [Pd(PCy3)2(Cl)2], [Pd(PPh3)2(Cl)2], [Pd(norbornadiene)(Cl)2], [Pd(TMEDA)(Cl)2], [Pd(TMEDA)(CH3)2], [Pd3(OAc)6], [Pd(CF3COO)2], [Pd(acetylacetonate)2], [Pd(COD)(Cl)2], and [Pd(allyl)(Cp)].

[0121] Nickel sources and salts include, for example, NiL2, NiL4, LNiX2, L2NiX2, L2Ni2X2 (wherein X and L are as defined above) and the corresponding adducts with solvents such as ethers, DMSO, or water.

[0122] The nickel sources and salts are preferably [Ni(COD)2], NiF2, NiCl2, NiBr2, NiI2, [Ni(OAc)2], [Ni(acetylacetonate)2], [Ni(Ph3P)2(Cl)2], [Ni((PPh2)2Fc)(Cl)2], [Ni2(methallyl)2(Cl)2], [Ni2(allyl)2(Cl)2], [Ni(CO)4], [Ni(PPh3)2(CO)2], [Ni(NO3)2], [Ni(OH)2], [Ni(PPh3)4], [Ni(CF3COO)2], [Ni(SO4)], [Ni(2-ethylhexanoate)2], [Ni(P(OPh)3)4], [Ni(CH7H 15 COO)2], [Ni(Cp)2], [Ni(PCy3)2(Cl)2], [Ni(PMe3)2(Cl)2], [Ni(PBu3)2(Br)2], and [Ni(dppe)(Cl)2].

[0123] The following abbreviations are used in the above palladium and nickel sources and salts: dba: dibenzylidene acetone Cy: Cyclohexyl COD: 1,5-cyclooctadiene Phen: Phenanthroline TMEDA: N,N,N',N'-tetramethylethylenediamine Fc: ferrocenyl Cp: ​​cyclopentadienyl

[0124] Many of the above palladium and nickel sources and salts are commercially available.

[0125] In a preferred embodiment, the transition metal complex is present in the form of a complex-type compound in homogeneous solution in the reaction medium.

[0126] Oxidation of the active metal, such as nickel or palladium, can cause partial deactivation of the carboxylation catalyst. This deactivation reduces the overall efficiency of the process. In this case, a reducing agent may be added. Apparently, the reducing agent reactivates the deactivated carboxylation catalyst by reducing the oxidized active metal. Any reducing agent capable of reducing the deactivated carboxylation catalyst is suitable as the reducing agent. Preferred reducing agents are H, Mg, Na, and Zn, or phosphine.

[0127] In step a) of the present process, a crude reaction product is obtained which comprises the conjugate acid of an α,β-ethylenically unsaturated carboxylic acid salt and an alkoxide.

[0128] Step a) may be carried out at a temperature in the range of, for example, 20 to 250° C., particularly 40 to 200° C., preferably 50 to 190° C., more preferably 60 to 180° C., and most preferably 70 to 180° C. Step a) may be carried out at a total pressure in the range of, for example, 1 to 300 bar, preferably 3 to 200 bar, and particularly 5 to 150 bar.

[0129] Step a) is preferably carried out in a reactor suitable for gas / liquid or liquid / liquid reactions at a given temperature and a given pressure. Suitable standard reactors for gas-liquid reaction systems are specified, for example, in KD Henkel, "Reactor Types and Their Industrial Application", Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley VCH Verlag GmbH & Co KGaA, DOI: 10.1002 / 14356007.b04_087, chapter 3.3 "Reactors for gas-liquid reactions". Examples include stirred tank reactors, tubular reactors, or bubble columns.

[0130] Step a) of the process according to the invention may be carried out continuously or discontinuously. Step a) is preferably carried out continuously. Step a) may also be carried out in several sequential reactors. In this embodiment, step a) is preferably carried out in a backmixed reactor, such as a stirred tank reactor or a jet loop reactor, and then in a tubular reactor.

[0131] In discontinuous step a), a carboxylation catalyst, which may be in the form of a ligand, e.g., a transition metal source, an alkoxide, an organic solvent, carbon dioxide, and an alkene are charged into a reactor. Preferably, gaseous carbon dioxide and gaseous alkene are passed through the reactor at a desired pressure. After the reaction slows down, the pressure may be reduced.

[0132] To achieve good mixing of the alkene, carbon dioxide, carboxylation catalyst, organic solvent, and alkoxide, suitable equipment can be used in step a). Such equipment can be a mechanical stirring device with one or more stirrers, with or without baffles, a packed or unpacked bubble column, a packed or unpacked flow tube with or without a static mixer, a jet loop reactor, or other useful equipment known to those skilled in the art for such process steps. The optional use of baffles and delay structures is expressly included in the process according to the invention.

[0133] The CO, alkene, and alkoxide may be fed to step a) together or spatially separated. Such spatial separation can be achieved in a simple manner, for example, in a stirred tank, by two or more separate inlets. For example, if more than one tank is used, there may be different medium changes in the different tanks. Separation of the addition of the CO and alkene reactants in terms of time is also possible in step a) of the process according to the invention. Such time separation can be achieved, for example, in a stirred tank, by staggered introduction of the reactants. When using a flow tube or similar type of apparatus, such introduction can be carried out, for example, at different positions in the flow tube; such varying introduction positions is an elegant way of adding reactants as a function of residence time.

[0134] In step a) of the process according to the invention, it is not necessary to feed CO2, alkene and alkoxide separately to the reaction.

[0135] In step b), the α,β-ethylenically unsaturated carboxylic acid salt is caused to precipitate from the crude reaction product. The ability to precipitate the α,β-ethylenically unsaturated carboxylic acid salt from the crude reaction product depends primarily on the temperature of the crude reaction product and the choice of organic solvent.

[0136] As mentioned above, the carboxylate salt is preferably insoluble in the organic solvent within the temperature range of the present process steps, especially steps a) to c), in which case the α,β-ethylenically unsaturated carboxylate salt precipitates from the crude reaction product as soon as it is formed and remains in solid form.

[0137] The choice of pressure and especially temperature at which step b) is carried out generally depends on the properties of the α,β-ethylenically unsaturated carboxylate salt. With regard to the efficiency of the process, it is preferred that the carboxylate salt is precipitated from the crude reaction product as soon as it is formed, and therefore at the same temperature and pressure at which step a) is carried out.

[0138] In another embodiment, the α,β-ethylenically unsaturated carboxylic acid salt is caused to precipitate from the crude reaction product at a temperature lower than and a similar pressure to the temperature and pressure at which step a) is carried out.

[0139] Step b) of the process according to the invention may be carried out continuously or discontinuously. Step b) is preferably carried out continuously.

[0140] In step c) of the process, at least a portion of the crude reaction product is subjected to a mechanical separation step, while maintaining the alcohol by-product in liquid form. A solid phase comprising the α,β-ethylenically unsaturated carboxylic acid salt is obtained together with a liquid phase comprising the carboxylation catalyst, the organic solvent, and the alcohol by-product.

[0141] It is essential to maintain the alcohol by-product in liquid or dissolved form to enable the precipitated α,β-ethylenically unsaturated carboxylate salt to be recovered as a high-purity solid phase. The temperature of the crude reaction product during mechanical separation step c) can be important, along with the choice of organic solvent, to maintain the alcohol by-product in liquid form while maintaining the carboxylate salt in solid form. The optimal temperature range for carrying out step c) of the present process depends on the properties of the obtained alcohol by-product and, therefore, the alkoxide used. This is particularly important when the alcohol by-product is insoluble in the organic solvent, for example, at low temperatures.

[0142] Generally, step c) may be carried out at a temperature in the range of 0 to 150°C.

[0143] In one embodiment, the temperature at which step c) is carried out is the same as the temperature at which step a) is carried out.

[0144] In another embodiment, the temperature at which step c) is carried out is lower than the temperature at which step a) is carried out. For example, if the alkoxide is sodium tert-butoxide and the alkene is ethene, the resulting carboxylate salt is sodium acrylate and the resulting alcohol by-product is tert-butanol. tert-Butanol has a melting point of approximately 25°C at 1 bar. It is important that the mechanical separation step c) be carried out at a temperature sufficiently higher than this temperature to maintain the tert-butanol in its liquid form and allow for high purity of the solid phase containing the carboxylate salt. In this embodiment, step a) is preferably carried out at a temperature in the range of 130-160°C, while step c) is preferably carried out at a temperature in the range of 70-90°C.

[0145] Step c) may be carried out at the same or a lower total pressure than step a). Step c) is preferably carried out at a lower total pressure than step a). The crude reaction product obtained from step a) may be depressurized, for example in a depressurization vessel, before being sent to step c). Any gases released from the crude reaction product during depressurization, i.e., CO2 and optionally alkene, are preferably recycled to the process, in particular to step a). Step c) is preferably carried out at a total pressure in the range of 0.01 to 20 bar, for example, 0.1 to 10 bar.

[0146] Preferably, the solid phase obtained in step c) comprises essentially all of the precipitated α,β-ethylenically unsaturated carboxylate salts of the crude reaction product that has been subjected to mechanical separation step c), for example the solid phase comprises at least 95%, at least 97%, at least 99%, or at least 99.5% by weight of the precipitated α,β-ethylenically unsaturated carboxylate salts of the crude reaction product that has been subjected to mechanical separation step c).

[0147] Preferably, the solid phase obtained in step c) essentially comprises only α,β-ethylenically unsaturated carboxylates, for example the carboxylates constitute at least 95%, at least 97%, at least 99% or at least 99.5% by weight of the solid phase obtained in step c), relative to the total weight of the solid phase.

[0148] Preferably, the liquid phase obtained in step c) comprises essentially all of the alcohol by-products of the crude reaction product that have been subjected to the mechanical separation step c). In addition to the alcohol by-products, the liquid phase obtained in step c) also typically comprises the organic solvent and the carboxylation catalyst, as well as unreacted alkene, carbon dioxide, and alkoxide.

[0149] The mechanical separation step c) may be carried out by any technique suitable for separating a solid phase from a liquid phase, examples of which include filtration steps, for example by vacuum or pressure filters, centrifugation steps, for example by filtration or sedimentation centrifuges or hydrocyclones, or sedimentation steps.

[0150] Preferably, the mechanical separation step c) comprises a filtration step.

[0151] Step c) of the process according to the invention may be carried out continuously or discontinuously. Step c) is preferably carried out continuously, for example by using a belt filter. A suitable belt filter comprises a gravity drainage zone, a linear compression pressure zone, and a roller compression zone. The crude reaction product is first fed to a flat or inclined gravity drainage zone, where gravity drainage of the liquid phase takes place. Next, the feed passes through a linear compression pressure zone, which comprises an upper belt and a lower belt arranged to pinch the feed together at low pressure. Finally, the feed passes through a roller compression zone, where the feed, while sandwiched between the upper and lower belts, is subjected to high pressure by a roller system.

[0152] In a preferred embodiment, the method may comprise step d) of distilling off the alcohol by-product and optionally the organic solvent from the liquid phase obtained in step c). An alcohol by-product distillation fraction and optionally a solvent distillation fraction, and a residual fraction are obtained. The relative boiling points of the alcohol by-product and the organic solvent determine whether the alcohol by-product or the organic solvent is distilled off first from the liquid phase.

[0153] When the boiling point of the organic solvent is higher than that of the alcohol by-product, it is preferred to distill only the alcohol by-product from the liquid phase obtained in step c). In this case, the obtained alcohol by-product distillation fraction contains the majority of the alcohol by-product, preferably at least 90%, more preferably at least 95%, in particular at least 97%, and most preferably at least 99% of the alcohol by-product contained in the liquid phase fed to step d). The remaining fraction generally contains the organic solvent and the carboxylation catalyst, as well as unreacted alkene, carbon dioxide, and alkoxide.

[0154] When the boiling point of the organic solvent is lower than that of the alcohol by-product, it is preferred to distill off both the alcohol by-product and the organic solvent from the liquid phase obtained in step c). In this case, it is preferred that the obtained solvent distillation fraction contains most of the organic solvent, preferably at least 90%, more preferably at least 95%, particularly at least 97%, and most preferably at least 99% of the organic solvent contained in the liquid phase fed to step d). The obtained alcohol by-product distillation fraction contains most of the alcohol by-product, preferably at least 85%, more preferably at least 90%, and particularly at least 95% of the alcohol by-product contained in the liquid phase fed to step d). The alcohol by-product distillation fraction and the solvent distillation fraction may exist as a single fraction or as separate fractions. The residual fraction generally contains the carboxylation catalyst, as well as unreacted alkene, carbon dioxide, and alkoxide, and preferably a small amount of alcohol by-product, which allows the carboxylation catalyst to be easily recycled to step a).

[0155] Step d) may be carried out in a distillation unit, for example comprising a distillation column, which may be equipped with trays or packing material. The liquid phase obtained in step c) is fed to the distillation unit, where it is heated and / or subjected to reduced pressure.

[0156] The pressure in step d) is, for example, in the range of 0.0001 to 10 bar, preferably 0.001 to 5 bar, and most preferably 0.01 to 2 bar. The temperature at the bottom of the distillation column is preferably maintained sufficiently higher than the boiling temperature of the alcohol by-product at the distillation pressure. The temperature at the bottom of the distillation column is, for example, in the range of 60 to 200°C, preferably 80 to 180°C.

[0157] Step d) may be carried out continuously or discontinuously. Step d) is preferably carried out continuously.

[0158] In a preferred embodiment, at least a portion of the resulting residue fraction is recycled to step a). The residue fraction may be recycled to step a) with or without further post-treatment steps, preferably without further post-treatment steps. Further post-treatment steps may include drying.

[0159] In some embodiments, the catalyst system may have low solubility in the alcohol by-product. In these cases, the boiling point of the organic solvent is preferably higher than that of the alcohol by-product, so that in step d), the alcohol by-product is first distilled off from the liquid phase, and the remaining fraction contains the organic solvent. Thus, the catalyst can be conveniently recycled to step a) in the organic solvent. When the alcohol by-product has a relatively high boiling point, it may be useful to use a higher-boiling organic cosolvent or a solvent mixture containing at least one solvent component with a boiling point higher than that of the alcohol by-product. Suitable higher-boiling organic cosolvents, which can be used individually or in mixtures, include the polyalkylene glycols or di- or mono(C1-C4-alkyl ether) polyalkylene glycols described above.

[0160] In a preferred embodiment, the method may include step e) of contacting at least a portion of the alcohol by-product distillate fraction obtained in step d) with an alkaline material to obtain a regenerated alkoxide. In this embodiment, the alkoxide is regenerated by reacting the alcohol by-product with an alkaline material capable of deprotonating the alcohol by-product so that the alkoxide is regenerated.

[0161] The alcohol by-product is generally contained in the alcohol by-product distillation fraction obtained in distillation step d) outside the carboxylation reactor. Therefore, the alcohol by-product can be contacted with an alkaline substance outside the carboxylation reactor, i.e., at low carbon dioxide partial pressure. Thus, a nucleophilic alkaline substance that is inactivated under the conditions of the reaction between alkene and carbon dioxide, i.e., at high carbon dioxide partial pressure, can be used to regenerate the alkoxide. This is advantageous because some of these alkaline substances, e.g., sodium hydroxide, are less expensive than other alkaline substances with lower nucleophilicity. It is preferred that the alcohol by-product distillation fraction be separate from the solvent distillation fraction optionally obtained in step d).

[0162] The alkaline substance used in step e) is preferably selected from alkali or alkaline earth metals, alkali and alkaline earth metal oxides and alkali and alkaline earth metal hydroxides, and mixtures thereof, in particular Li, Na, K, Ca, Li2O, Na2O, KO, CaO, LiOH, NaOH, KOH, Ca(OH)2, and mixtures thereof. Sodium hydroxide is the most preferred alkaline substance used in step e).

[0163] Alternative alkaline materials that can be used in step e) are selected from, for example, alkali metal or alkaline earth metal hydrides, amides, phosphides, silanolates, lower alkoxides (e.g., methoxides), alkali metal or alkaline earth metal alkyls and aryls, which are similarly or even more reactive towards the alcohol by-product, but are more difficult to handle and / or more expensive than the preferred alkaline materials mentioned above.

[0164] Suitable alkali metal or alkaline earth metal hydrides are, for example, lithium hydride, sodium hydride, potassium hydride, magnesium hydride, and calcium hydride.

[0165] Suitable lower alkoxides are, for example, lithium methoxide, lithium ethoxide, sodium methoxide, sodium ethoxide, sodium isopropoxide, potassium methoxide, magnesium methoxide, and calcium methoxide.

[0166] Suitable alkali metal or alkaline earth metal amides are, for example, LiNH, NaNH, KNH, LiNMe, LiNEt, LiN(iPr), NaNMe, NaNEt, NaN(iPr), KNMe, KNEt, KN(iPr), (Me=methyl; Et=ethyl; iPr=isopropyl). Suitable amides also include silicon-containing amides, such as sodium hexamethyldisilazide (NaHMDS), potassium hexamethyldisilazide (KHMDS), or lithium hexamethyldisilazide (LiHMDS).

[0167] Suitable alkali metal or alkaline earth metal phosphides include, for example, those of the formula M 2 PR 101 2 (in the formula, M 2 is the alkali metal or alkaline earth metal equivalent, and R 101 is C 1~12 -alkyl or C 6~10 -aryl), for example KPPh2 or NaPPh2 (Ph=phenyl).

[0168] Suitable alkali metal or alkaline earth metal silanolates are, for example, compounds of the formula M 2 OSi(C 1~4 -alkyl)3 (wherein M 2 is the alkali metal or alkaline earth metal equivalent), for example, NaOSiMe3.

[0169] Suitable alkali metal or alkaline earth metal alkyls or aryls include, for example, lithium alkyl and aryl compounds, such as methyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, phenyllithium (the benzene ring may have a substituent at any position (e.g., OCH, CHNMe, CONR)), cyclohexyllithium (the cyclohexyl ring may contain a heteroatom (e.g., O, N, S)), ethyllithium, lithium pentadienyl, lithium 2-furanyl, lithium 2-thiophenyl, and lithium ethynyl. Sodium alkyl and aryl compounds, such as sodium cyclopentadienyl, are also suitable.

[0170] Suitable alkaline earth metal alkyls and aryls include those of the general formula R 102 MgX (wherein, R 102 may be one of the alkyl and aryl residues listed above for the lithium alkyl and lithium aryl compounds, and X may be F, Cl, Br, or I.

[0171] When the alkaline substance is selected from alkali or alkaline earth metals, such as sodium, lithium, or potassium, especially sodium, deprotonation of the alcohol by-product is coupled with a redox reaction: the alkali or alkaline earth metal is oxidized to an alkali or alkaline earth metal cation, and the protons attached to the oxygen of the alcohol by-product are reduced to hydrogen.

[0172] The regeneration of the alkoxide is preferably carried out in the liquid or supercritical phase at a pressure in the range of 0.0001 to 150 bar, preferably 0.001 to 100 bar, more preferably 0.001 to 60 bar. The temperature may be, for example, in the range of -20 to 300°C, preferably 20 to 250°C, more preferably 40 to 200°C.

[0173] Step e) may be carried out continuously or discontinuously. Step e) is preferably carried out continuously.

[0174] Preferably, at least a portion of the regenerated alkoxide obtained in step e) is recycled to step a). The regenerated alkoxide obtained in step e) may be, for example, dried and recycled to step a) in the form of a solid or in the form of a solution in an organic solvent.

[0175] In a preferred embodiment, the method comprises a step f) of contacting the solid phase obtained in step c) with a wash liquid to obtain a spent wash liquid and a purified solid phase enriched in carboxylate salts. Advantageously, the wash liquid is suitable for removing a large amount of carboxylation catalyst impurities from the solid phase, thus making it possible to obtain carboxylate salts in higher purity.

[0176] The washing liquid is preferably selected from liquids that are inert to the carboxylate salt and in which the carboxylate salt is essentially insoluble. The washing liquid may be selected from alkanes, such as butane, pentane, hexane, or heptane in their linear or branched forms, for example, n-pentane; alcohols, such as propanol, butanol, pentanol, or hexanol in their linear or branched forms, and ethers, such as diethyl ether, methyl tert-butyl ether, and tetrahydrofuran. In a preferred embodiment, the washing liquid is selected from n-pentane and the conjugate alcohol of the alkoxide. Most preferably, the washing liquid is the conjugate alcohol of the alkoxide.

[0177] In one embodiment, the cleaning solution is a conjugated alcohol of the alkoxide, i.e., an alcohol by-product. In this embodiment, it is preferred that at least a portion of the used cleaning solution is fed to step d). For example, at least 40%, e.g., at least 60% or at least 80% of the used cleaning solution is recycled to step d).

[0178] In another embodiment, the washing liquid is the organic solvent of step a). In this case, it is preferred that at least a portion of the used washing liquid is recycled to step a). For example, at least 40%, for example, at least 60% or at least 80% of the used washing liquid is recycled to step a). The organic solvent used as the washing liquid is advantageously purified before being recycled to step a). For example, the organic solvent used as the washing liquid may be distilled before being recycled to step a).

[0179] It may be necessary to heat the cleaning liquid to a temperature above its melting point before use. For example, tert-butanol has a melting point of approximately 25°C at 1 bar absolute pressure. Therefore, the tert-butanol is preferably heated to a temperature of at least 40°C, more preferably at least 60°C, and most preferably at least 70°C, for example at least 80°C.

[0180] Step f) of the method according to the present invention may be carried out continuously or discontinuously. Step f) is preferably carried out continuously. When a filter is used in the mechanical separation step c), step f) may be carried out directly on the filter. Alternatively, step f) may be carried out by suspending the solid phase obtained in step c) in a washing liquid, followed by a mechanical separation step, for example, filtration. [Example]

[0181] The invention will now be described in more detail by the following examples illustrating the preparation of sodium acrylate.

[0182] The identity and purity of the sodium acrylate produced was analytically confirmed using high-performance liquid chromatography (HPLC) analysis of the reaction product after treatment with 0.1% aqueous H3PO4. The turnover numbers (TON) reported below are subject to an error of up to 15% resulting from the test setup. This is due to the inherent error in weighing and the sticky, viscous nature of the autoclave discharge.

[0183] In the examples, the following abbreviations are used: dcpe: 1,2-bis(dicyclohexylphosphino)ethane DMF: N,N-dimethylformamide TON: Turnover number for transition metals

[0184] <Example 1> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh3)4 (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium tert-butoxide (40.00 mmol, 3.84 g), and DMF (60 mL). The autoclave was stirred at 500 rpm for 15 minutes to solubilize the reactants. The autoclave was pressurized with CO2 (35 bar), ethene (10 bar), and nitrogen (25 bar) at 25 °C (70 bar total pressure). After stirring at 750 rpm for 16 hours at 145 °C, the autoclave was cooled to 80 °C, the pressure was released, and the reaction mixture, i.e., crude reaction product, was transferred to a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred to a bottle. The product was separated from the reaction mixture by hot filtration at 80°C under reduced pressure. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to give the product as a white solid. A quantitative yield of 3.90 g was obtained, corresponding to a TON of 104.

[0185] <Example 2> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh3)4 (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium 3,7-dimethyloctan-3-olate (40.00 mmol, 7.21 g), and DMF (60 mL). The autoclave was stirred at 500 rpm for 15 minutes to solubilize the reactants. The autoclave was pressurized with CO2 (35 bar) and ethene (10 bar) at 25 °C. After stirring at 750 rpm for 5 hours at 145 °C, the autoclave was cooled to 80 °C, the pressure was released, and the reaction mixture, i.e., the crude reaction product, was transferred into a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred into the bottle. The product was separated from the reaction mixture by filtration under reduced pressure at room temperature. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to give the product as a white solid. A yield of 3.00 g (80%) was obtained, corresponding to a TON of 80.

[0186] <Example 3> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh3)4 (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium 3,7-dimethyloctan-3-olate as a 48% solution in 3,7-dimethyloctan-3-ol (40 mmol, 15.4 g), and DMF (53 mL). The autoclave was stirred at 500 rpm for 15 minutes to solubilize the reactants. The autoclave was pressurized with CO2 (35 bar) and ethene (10 bar) at 25 °C. After stirring at 145 °C and 750 rpm for 5 hours, the autoclave was cooled to 80 °C, the pressure was released, and the reaction mixture, i.e., crude reaction product, was transferred into a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred to a bottle. The product was separated from the reaction mixture by filtration under reduced pressure at room temperature. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to give the product as a white solid. A yield of 2.88 g (77%) was obtained, corresponding to a TON of 77.

[0187] <Example 4> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh) (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium 3,7-dimethyloctan-3-olate (40.00 mmol, 15.4 g) as a 48% solution in 3,7-dimethyloctan-3-ol, 3,7-dimethyloctan-3-ol (20 mL), and DMF (30 mL). The autoclave was stirred at 500 rpm for 15 min to solubilize the reactants. The autoclave was pressurized with CO (35 bar) and ethene (10 bar) at 25 °C. After stirring at 145°C and 750 rpm for 5 hours, the autoclave was cooled to 80°C, the pressure was released, and the reaction mixture, i.e., the crude reaction product, was transferred into a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred into a bottle. The product was separated from the reaction mixture by filtration under reduced pressure at room temperature. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to obtain the product as a white solid. A yield of 3.05 g (81%) was obtained, corresponding to a TON of 81.

[0188] <Example 5> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh) (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium 3,7-dimethyloctan-3-olate (40.00 mmol, 15.4 g) as a 48% solution in 3,7-dimethyloctan-3-ol, 3,7-dimethyloctan-3-ol (20 mL), and DMF (30 mL). The autoclave was stirred at 500 rpm for 15 min to solubilize the reactants. The autoclave was pressurized with CO (35 bar) and ethene (10 bar) at 25 °C. After stirring at 145°C and 750 rpm for 5 hours, the autoclave was cooled to 80°C, the pressure was released, and the reaction mixture, i.e., the crude reaction product, was transferred into a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred into a bottle. The product was separated from the reaction mixture by filtration under reduced pressure at room temperature. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to obtain the product as a white solid. A yield of 2.84 g (76%) was obtained, corresponding to a TON of 76.

[0189] <Example 6> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh3)4 (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium 3-methylpentan-3-olate (40.00 mmol, 4.97 g), and DMF (60 mL). The autoclave was stirred at 500 rpm for 15 minutes to solubilize the reactants. The autoclave was pressurized with CO2 (35 bar) and ethene (10 bar) at 25 °C. After stirring at 145 °C and 750 rpm for 5 hours, the autoclave was cooled to 80 °C, the pressure was released, and the reaction mixture, i.e., the crude reaction product, was transferred to a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred to the bottle. The product was separated from the reaction mixture by filtration under reduced pressure at room temperature. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to give the product as a white solid. A quantitative yield of 3.91 g was obtained, corresponding to a TON of 104.

[0190] <Example 7> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh3)4 (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium 3-methylpentan-3-olate (40.00 mmol, 4.97 g), and DMF (60 mL). The autoclave was stirred at 500 rpm for 15 minutes to solubilize the reactants. The autoclave was pressurized with CO2 (35 bar) and ethene (10 bar) at 25 °C. After stirring at 145 °C and 750 rpm for 5 hours, the autoclave was cooled to 80 °C, the pressure was released, and the reaction mixture, i.e., the crude reaction product, was transferred into a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred into the bottle. The product was separated from the reaction mixture by filtration under reduced pressure at room temperature. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to give the product as a white solid. A yield of 3.14 g (84%) was obtained, corresponding to a TON of 84.

[0191] <Example 8> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh3)4 (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium 3,7-dimethyloctan-3-olate (40.00 mmol, 14.1 g) as a 51% solution in 3,7-dimethyloctan-3-ol (40.00 mmol, 14.1 g), and DMF (54 mL). The autoclave was stirred at 500 rpm for 15 min to solubilize the reactants. The autoclave was pressurized with CO2 (35 bar) and ethene (10 bar) at 25 °C. After stirring at 145 °C and 750 rpm for 5 h, the autoclave was cooled to 80 °C, the pressure was released, and the reaction mixture, i.e., crude reaction product, was transferred into a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred to a bottle. The product was separated from the reaction mixture by filtration under reduced pressure at room temperature. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to give the product as a white solid. A quantitative yield of 4.28 g was obtained, corresponding to a TON of 114.

[0192] <Example 9> A 270 mL steel autoclave was charged under argon using standard Schlenk techniques with Pd(PPh3)4 (0.400 mmol, 0.463 g), dcpe (0.440 mmol, 0.187 g), sodium 3-ethyl-pentan-3-olate (40.00 mmol, 5.52 g), and DMF (60 mL). The autoclave was stirred at 500 rpm for 15 minutes to solubilize the reactants. The autoclave was pressurized with CO2 (35 bar) and ethene (10 bar) at 25 °C. After stirring at 145 °C and 750 rpm for 5 hours, the autoclave was cooled to 80 °C, the pressure was released, and the reaction mixture, i.e., the crude reaction product, was transferred into a 100 mL bottle. The residue in the autoclave vessel was recovered with 15 mL of DMF and transferred into the bottle. The product was separated from the reaction mixture by filtration under reduced pressure at room temperature. The resulting sticky solid was washed with 3 x 25 mL of DMF, followed by 3 x 25 mL of n-pentane. The solid residue was dried under vacuum to give the product as a white solid. A quantitative yield of 3.92 g was obtained, corresponding to a TON of 104.

Claims

1. 1. A catalytic process for producing an α,β-ethylenically unsaturated carboxylic acid salt, comprising: a) reacting an alkene and carbon dioxide with a carboxylation catalyst, an organic solvent, and [O － ] group to obtain a crude reaction product comprising an α,β-ethylenically unsaturated carboxylic acid salt and an alcohol by-product which is the conjugate acid of the alkoxide; b) precipitating the α,β-ethylenically unsaturated carboxylic acid salt from the crude reaction product; and c) subjecting at least a portion of the crude reaction product to a mechanical separation step, while maintaining the alcohol by-product in liquid form, to obtain a solid phase comprising the α,β ethylenically unsaturated carboxylic acid salt and a liquid phase comprising the carboxylation catalyst, the organic solvent, and the alcohol by-product. A catalytic method, including

2. 10. The catalytic process of claim 1, wherein said mechanical separation step c) comprises a filtration step.

3. d) distilling the alcohol by-product and optionally the organic solvent from the liquid phase to obtain an alcohol by-product distillation fraction and optionally a solvent distillation fraction, and a residue fraction.

3. The catalytic method of claim 1 or 2, further comprising:

4. 4. The catalytic process of claim 3, further comprising recycling at least a portion of the residual fraction to step a).

5. e) contacting at least a portion of the alcohol by-product distillation fraction obtained in step d) with an alkaline material to regenerate the alkoxide.

5. The catalytic method of claim 3 or 4, further comprising:

6. 6. The catalytic process of claim 5, further comprising recycling at least a portion of the regenerated alkoxide to step a).

7. f) contacting the solid phase obtained in step c) with a washing liquid to obtain spent washing liquid, and obtaining a purified solid phase enriched in carboxylates.

7. The catalytic process of claim 1, further comprising:

8. 8. The catalytic process of claim 7, wherein the wash liquid is selected from alkanes and alcohols.

9. 9. The catalytic method of claim 8, wherein the wash liquid is the alcohol by-product.

10. 9. The catalytic method of claim 8, wherein the washing liquid is the organic solvent.

11. 11. The catalytic process of any one of claims 1 to 10, wherein the organic solvent is selected from N,N-disubstituted formamides, N,N-disubstituted acetamides, N-substituted 2-pyrrolidones, and 1,3-disubstituted 2-imidazolidinones.

12. 12. A catalytic process according to claim 11, wherein the organic solvent is an N,N-disubstituted formamide, preferably an N,N-dialkylated formamide.

13. 13. A catalytic process according to any one of claims 1 to 12, wherein step c) is carried out at a temperature in the range of from 0 to 150°C.

14. The alkoxide is preferably a sodium alkoxide, － 14. A catalytic process according to any one of claims 1 to 13, wherein the alkoxide is a sodium alkoxide having a secondary or tertiary carbon atom directly bonded to a ] group.

15. 15. The catalytic process of any one of claims 1 to 14, wherein the alkene is ethene and the α,β-ethylenically unsaturated carboxylic acid salt is sodium acrylate.

16. 16. The catalytic process of any one of claims 1 to 15, wherein the carboxylation catalyst is a nickel or palladium complex comprising a bidentate P,X ligand, where X is selected from the group consisting of P, N, O and carbene, and the P and X atoms are separated by a divalent linker comprising 2 to 4 bridging atoms.

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