Process for preparing an unsaturated carboxylic acid salt

Abstract

The present invention relates to a catalytic process for preparing an ,-ethylenically unsaturated carboxylic acid salt, comprising contacting an alkene and carbon dioxide with a carboxylation catalyst being a transition metal complex, an alkoxide, and an organic solvent, to obtain an ,-ethylenically unsaturated carboxylic acid salt, the organic solvent being incompletely miscible with water at a pressure of 1 bar at at least one temperature T and selected from amides and ureas, T being a temperature in the range from 10 C. to 90 C.

Claims

1. A catalytic process, suitable for preparing an ,-ethylenically unsaturated carboxylic acid salt, the process comprising contacting an alkene and carbon dioxide with a carboxylation catalyst to obtain an ,-ethylenically unsaturated carboxylic acid salt, wherein the carboxylation catalyst comprises a nickel or palladium complex, an alkoxide, and an organic solvent, wherein the organic solvent is incompletely miscible with water at a pressure of 1 bar at at least one temperature T and is selected from the group consisting of an amide and a urea, T being a temperature in a range from 10 C. to 90 C. wherein the amide or the urea is linear or cyclic and comprises at least 5 carbon atoms and no nitrogen bound hydrogen atoms and wherein all of the at least 5 carbon atoms other than the carbonyl carbon atom are saturated.

2. The catalytic process according to claim 1, wherein the organic solvent is an N,N-disubstituted formamide, an N,N-disubstituted acetamide, an N-substituted 2-pyrrolidone, or a 1,3-disubstituted 2-imidazolidinone.

3. The catalytic process according to claim 2, wherein the organic solvent is selected from the group consisting of N-Methylpyrrolidone, N-Ethylpyrrolidone, 1,3-Dimethyl-2-imidazolidinone, N-Cyclohexylpyrrolidone, N,N-Dibutylformamide, N,N-Dihexylformamide, N,N-Dibutylacetamide, N,N-Dihexylacetamide, N-Cyclohexylpyrollidone, and N-Decylpyrollidone.

4. The catalytic process according to claim 1, wherein the alkoxide comprises a secondary or tertiary carbon atom directly bound to an [O.sup.]group.

5. The catalytic process according to claim 1, wherein the alkoxide is selected from the group consisting of an alkali metal alkoxide and an alkaline earth metal alkoxide.

6. The catalytic process according to claim 1, wherein the alkene and the carbon dioxide are contacted with the carboxylation catalyst, the alkoxide, and the organic solvent at a temperature in a range from 105 to 170 C.

7. The catalytic process according to claim 1, wherein the nickel or palladium complex comprises a bidentate P,X ligand, wherein X is selected from the group consisting of P, N, O, and carbene, and P and X are separated by a bivalent linker that comprises 2 to 4 bridging atoms.

8. The catalytic process according to claim 1, wherein the alkene is ethene and the ,-ethylenically unsaturated carboxylic acid is acrylic acid.

9. The catalytic process according to claim 1, additionally comprising contacting at least part of a crude reaction product with a polar solvent to obtain: a first liquid phase in which the ,-ethylenically unsaturated carboxylic acid salt is enriched, and a second liquid phase in which the carboxylation catalyst is enriched.

10. The catalytic process according to claim 9, additionally comprising distilling off an alcohol byproduct from the first liquid phase, to obtain a recovered alcohol byproduct, contacting at least part of the recovered alcohol byproduct with an alkaline material to obtain a regenerated alkoxide, and recycling at least part of the regenerated alkoxide into the catalytic process.

11. The catalytic process according to claim 10, wherein the polar solvent has a boiling temperature of less than 150 C. at a pressure of 1 bar.

12. The catalytic process according to claim 11, wherein the polar solvent is aqueous.

13. The catalytic process according to claim 12, wherein at least a part of the polar solvent is distilled off from the first liquid phase.

Description

EXAMPLES 1 TO 13 (TABLE 1)

(1) A 60 mL steel autoclave, inside a glovebox was charged with a transition metal source, ligand, and alkoxide and the obtained solid mixture was dissolved in a solvent. The autoclave was removed from the glovebox and charged, under stirring at 800 rpm, with the given pressure of ethylene and the given pressure of CO.sub.2 for 15 min each at 25 C. After stirring at the given temperature for the given time at 800 rpm, the autoclave was cooled to 20 C., the pressure was released and the reaction mixture, i.e. crude reaction product, was transferred into a 100 mL glass bottle. The residues in the autoclave vessel were recovered with 15 mL of D.sub.2O and transferred in the glass bottle. To this biphasic mixture, 3-(trimethylsilyl)propionic-2,2,3,3-d.sub.4 acid sodium salt (0.13 mmol, 0.0216 g), an additional 10 mL of D.sub.2O, and 40 mL of Et.sub.2O were added. The organic phase, i.e. the second liquid phase, contains the carboxylation catalyst and can be recycled. From the aqueous phase, i.e. the first liquid phase, an aliquot was collected, centrifuged and analyzed by .sup.1H-NMR to determine the TON. Each .sup.1H-NMR spectrum showed that the aqueous phase contains the ,-ethylenically unsaturated carboxylic acid salt (sodium acrylate), the alcohol byproduct and water. All volatiles were removed in vacuo from the aqueous phase to obtain the desired sodium acrylate as the residue. The residue was dissolved in D.sub.2O and a second .sup.1H-NMR spectrum was detected. The resonances of the methyl protons of the alcohols were not present in any second .sup.1H-NMR spectrum, which shows that the iso-propanol or tertiary butanol byproduct was quantitatively removed when the aqueous solvent was evaporated.

EXAMPLES 14 TO 19 (TABLE 2)

(2) A 60 mL steel autoclave, inside a glovebox was charged with a transition metal source, ligand, and alkoxide and the obtained solid mixture was dissolved in a solvent. The autoclave was removed from the glovebox and charged, under stirring at 700 rpm, with the given pressure of ethylene and the given pressure of CO2 for 15 min each at 25 C. After stirring at the given temperature for the given time at 700 rpm, the autoclave was cooled to 20 C., the pressure was released and the reaction mixture, i.e. crude reaction product, was transferred into a 100 mL glass bottle. The residues in the autoclave vessel were recovered with 30 mL of H2O and transferred in the glass bottle. From the aqueous phase, i.e. the first liquid phase, an aliquot was collected, acidified with H3PO4 and analyzed by HPLC to determine the TON. The HPLC chromatogram showed that the aqueous phase contained the acetic acid which is the acid formed by acidifying the carboxylation product (acrylate salt).

EXAMPLES 20 TO 24 (TABLE 3)

(3) A 100 mL Schlenk inside a glovebox was charged with Pd(PPh3)4, ligand, alkoxide, and solvent. The mixture was stirred at room temperature for 1 hour. Then, the mixture was transferred with argon to a 300 mL steel autoclave. The mixture was stirring at 700 rpm and charged with 10 bar of ethylene for 15 min at 25 C. and then with 35 bar of CO2 for 15 min at 25 C. (45 bar total pressure at 25 C.). After stirring for 16 hours at 145 C. (70-80 bar at 145 C.) the autoclave was cooled down to 20 C., the pressure was released, and the reaction mixture, i.e. the crude reaction product, was transferred into a 100 mL glass bottle. The residues in the autoclave vessel were recovered with 30 mL of H.sub.2O and transferred in a glass bottle. The aqueous phase containing the product was separated from the organic phase which contains the carboxylation catalyst that can be recycled. From the aqueous phase, an aliquot was collected (1 mL), acidified with H.sub.3PO.sub.4, and the generated acrylic acid analyzed by HPLC. The TON was determined from the HPLC analytics.

(4) TABLE-US-00001 TABLE 1 Transition metal source Alkoxide Ligand Ethene CO.sub.2 Solvent Time Temperature Example (mmol) (mmol) (mmol) [bar] [bar] (mL) [h] [ C.] TON 1 [Pd(dcpe)(NaAcr)] (0.1) NaOtBu (20) Dcpe (0.11) 10 40 DMAc (30) 20 145 55 2 [Pd(dcpe)(NaAcr)] (0.1) NaOtBu (20) Dcpe (0.11) 10 40 NMP (30) 20 145 55 3 [Pd(dcpe)(NaAcr)] (0.1) NaOtBu (20) Dcpe (0.11) 10 40 DMI (30) 20 145 80 4 [Pd(dcpe)(NaAcr)] (0.1) NaOtBu (20) Dcpe (0.11) 10 40 NEP (30) 20 145 60 5 [Pd(dcpe)(NaAcr)] (0.1) NaOtBu (20) Dcpe (0.11) 10 40 DBF (30) 20 145 51 6 [Pd(dcpe)(NaAcr)] (0.1) NaOtBu (20) Dcpe (0.11) 10 40 CHP (30) 20 145 152 7 [Pd(PPh.sub.3).sub.4] (0.01) NaOtBu (25) Dcpe (0.011) 10 40 CHP (30) 5 145 422 8 [Pd(PPh.sub.3).sub.4] (0.01) NaOiPr (25) Dcpe (0.011) 10 40 CHP (30) 20 145 200 9 [Pd(PPh.sub.3).sub.4] (0.2) NaOtBu (15) Dcpe (0.22) 10 40 DBF (30) 20 145 130 10 [Pd(PPh.sub.3).sub.4] (0.2) NaOiPr (15) Dcpe (0.22) 10 40 DBF (30) 20 145 30 11 [Pd(PPh.sub.3).sub.4] (0.01) NaOtBu (25) Dcpe (0.011) 10 40 CHP (30) 20 145 514 12 [Pd(PPh.sub.3).sub.4] (0.01) NaOtBu (25) Dcpe (0.011) 10 40 DBF (30) 106 145 270 13 [Pd(PPh.sub.3).sub.4] (0.2) NaOtBu (25) Dcpe (0.22) 10 40 DBF (30) 20 145 130

(5) TABLE-US-00002 TABLE 2 Transition metal source Alkoxide Ligand Ethene CO.sub.2 Solvent Time Temperature Example (mmol) (mmol) (mmol) [bar] [bar] (mL) [h] [ C.] TON 14 [Ni(COD).sub.2] (0.1) NaOtBu (4.6) Dcpe (0.11) 10 30 DBF (30) 16 145 26 15 [Ni(COD).sub.2] (0.2) NaOtBu (20) Dcpe (0.22) 10 30 Dimethyl- 16 145 23 hexanamide (30) 16 [Ni(COD).sub.2] (0.1) NaOsecBu (4.6) Dcpe (0.11) 10 30 DBF (30) 16 145 12 17 [Ni(COD).sub.2] (0.1) NaOiPr (4.6) Dcpe (0.11) 10 30 DBF (30) 16 145 29 18 [Ni(COD).sub.2] (0.1) NaOCy (4.6) Dcpe (0.11) 10 30 DBF (30) 16 145 17 19 [Ni(COD).sub.2] (0.1) NaOtPentoxide (4.6) Dcpe (0.11) 10 30 DBF (30) 16 145 3

(6) TABLE-US-00003 TABLE 3 Transition metal source Alkoxide Ligand Ethene CO.sub.2 Solvent Time Temperature Example (mmol) (mmol) (mmol) [bar] [bar] (mL) [h] [ C.] TON 20 [Pd(PPh.sub.3).sub.4] (0.2) NaOsecBu (20) Dcpe (0.22) 10 35 DBF (30) 16 145 21 21 [Pd(PPh.sub.3).sub.4] (0.2) NaO(2-pentyl) Dcpe (0.22) 10 35 DBF (30) 16 145 31 (20) 22 [Pd(PPh.sub.3).sub.4] (0.2) NaO(3-methyl-2- Dcpe (0.22) 10 35 DBF (30) 16 145 65 butyl)) (20) 23 [Pd(PPh.sub.3).sub.4] (0.2) NaO(2,4- Dcpe (0.22) 10 35 DBF (30) 16 145 46 Bismethyl-3- pentyl) (20) 24 [Pd(PPh.sub.3).sub.4] (0.2) NaOtBu (20) Dcpe (0.22) 10 35 N,N-Diisobutyl- 16 145 99 formamide (30)