Process for preparing an unsaturated carboxylic acid salt using an aryloxide
Catalytic process for preparing an α,β-ethylenically unsaturated carboxylic acid salt, wherein an alkene and carbon dioxide are reacted in the presence of a carboxylation catalyst and in the presence of a specific aryloxide to obtain the α,β-ethylenically unsaturated carboxylic acid salt, the carboxylation catalyst being a transition metal complex. The process allows for efficient preparation of α,β-ethylenically unsaturated carboxylic acid derivatives from CO 2 and an alkene.
1. A catalytic process for preparing an α,β-ethylenically unsaturated carboxylic acid salt, the catalytic process comprising reacting an alkene and carbon dioxide in the presence of a carboxylation catalyst and an aryloxide to obtain the α,β-ethylenically unsaturated carboxylic acid salt,
wherein:
the carboxylation catalyst is a transition metal complex;
the aryloxide corresponds to formula (I):
R is selected from the group consisting of F, Cl, Br, I, a C 1 -C 16 -alkyl, and a C 3 -C 16 -cycloalkyl, and two vicinal R groups may constitute a C 3 -C 5 -hydrocarbylene bridge that is optionally substituted by one to four substituents which are independently selected from the group consisting of F, Cl, Br, I, a C 1 -C 16 -alkyl, and a C 3 -C 16 -cycloalkyl;
n is an integer selected from 1 to 5; and
at most two R groups are F.
2. The catalytic process according to claim 1 , wherein two vicinal R groups constitute an unsaturated C 4 -hydrocarbylene bridge that is optionally substituted by one to four substituents which are independently selected from the group consisting of F, Cl, Br, I, ua C 1 -C 16 -alkyl, and a C 3 -C 16 -cycloalkyl.
3. The catalytic process according to claim 1 , wherein:
the aryloxide corresponds to one of the formulae (Ia), (Ib), and (Ic):
o is 0, 1, 2, or 3;
p is 0, 1, or 2;
q is 0, 1, or 2;
the sum of o, p, and q is at least 1;
r, s, t, u, v, and w are 0 or integers;
the sum of r and u is 0, 1, 2, or 3;
the sum of s and v is 0, 1, or 2;
the sum oft and w is 0, 1, or 2; and
R 1 is selected from the group consisting of Br, I, a C 1 -C 16 -alkyl, and a C 3 -C 16 -cycloalkyl.
4. The catalytic process according to claim 3 , wherein the aryloxide corresponds to the formula (Ia), in which the sum of p and q is at most 3.
5. The catalytic process according to claim 3 , wherein:
the aryloxide corresponds to the formula (Ia);
p is at most 1;
q is at most 2; and
the sum of p and q is 1 or 2.
6. The catalytic process according to claim 3 , wherein R 1 is a C 1 -C 16 -alkyl or a C 3 -C 16 -cycloalkyl.
7. The catalytic process according to claim 1 , wherein:
the aryloxide corresponds to one of the formulae (Ia-1), (Ia-2), and (Ia-3):
x is 0, 1, or 2;
R 2 is methyl; and
R 3 is independently a C 1 -C 16 -alkyl or a C 3 -C 16 -cycloalkyl.
8. The catalytic process according to claim 7 , wherein:
the aryloxide corresponds to formula (Ia-2) or (Ia-3); and
x is 1 or 2.
9. The catalytic process according to claim 7 , wherein:
the aryloxide corresponds to formula (Ia-2) with F being ortho to O − ; and
x is 1 or 2.
10. The catalytic process according to claim 1 , wherein the aryloxide is an alkali metal, an alkaline earth metal or a zinc aryloxide.
11. The catalytic process according to claim 1 , wherein the aryloxide is selected from the group consisting of sodium 2-fluorophenolate, sodium 3-fluorophenolate, sodium 4-fluorophenolate, sodium 2,6-difluorophenolate, sodium 2,4-difluorophenolate, sodium 2-chlorophenolate, sodium 3-chlorophenolate, sodium 4-chlorophenolate, sodium 2-fluoro-4-methylphenolate, sodium 2-methylphenolate, sodium 2,6-dimethylphenolate, and sodium 1-naphtholate.
12. The catalytic process according to claim 1 , wherein the aryloxide is selected from the group consisting of sodium 2-fluorophenolate, sodium 3-fluorophenolate, sodium 2-chlorophenolate, sodium 3-chlorophenolate, and sodium 2-fluoro-4-methylphenolate.
13. The catalytic process according to claim 1 , wherein:
R is independently selected from the group consisting of a C 1 -C 16 -alkyl and a C 3 -C 16 -cycloalkyl;
n is an integer from 2 to 5; and
one R is at position 2 and another R is at position 6 of the phenyl ring of general formula (I).
14. The catalytic process according to claim 13 , wherein:
R is independently a C 1 -C 6 -alkyl; and
n is 2 or 3.
15. The catalytic process according to claim 13 , wherein the aryloxide is a sodium aryloxide.
16. The catalytic process according to claim 1 , wherein the transition metal complex comprises a ligand selected from the group consisting of a bidentate P,P ligand, a bidentate P,N ligand, a bidentate P,O ligand and a P,carbene ligand.
17. The catalytic process according to claim 16 , wherein the ligand is a bidentate P,P ligand.
18. The catalytic process according to claim 1 , wherein the transition metal complex is a nickel or a palladium complex.
19. The catalytic process according to claim 1 , wherein:
the alkene is ethene; and
the α,β-ethylenically unsaturated carboxylic acid is acrylic acid.
20. The catalytic process according to claim 1 , wherein the alkene and the carbon dioxide are reacted in the presence of a reducing agent.
21. The catalytic process according to claim 1 , wherein the reacting occurs in the presence of a reaction medium comprising an aprotic organic solvent.
22. The catalytic process according to claim 21 , wherein the aprotic organic solvent is selected from the group consisting of
a cyclic alkyl ether having 4 to 8 carbon atoms,
a dialkyl ether having 2 to 12 carbon atoms,
a cycloalkyl alkyl ether having 4 to 12 carbon atoms,
an aryl alkyl ether having 7 to 16 carbon atoms,
a biaryl having 12 to 16 carbon atoms,
a diaryl oxide having 12 to 16 carbon atoms,
a C 1 -C 8 -alkyl ester of a C 6 -C 10 -aryl monocarboxylic acid,
a di-C 1 -C 8 -alkyl ester of a C 6 -C 10 -aryl dicarboxylic acid,
a dialkyl carbonate having 3 to 13 carbon atoms,
a diether consisting of an dioxyalkylene residue with 2 to 8 carbon atoms and two C 1 -C 8 -alkyl residues,
a benzene wherein 1 to 4 hydrogen atoms are substituted by 1 to 4 C 1 -C 4 -alkyl residues,
a halogenated benzene,
an alkane having 5 to 18 carbon atoms, and
mixtures thereof.
23. The catalytic process according to claim 1 , wherein:
the reacting occurs in the presence of a reaction medium;
the α,β-ethylenically unsaturated carboxylic acid salt is removed from the reaction medium;
the removal of the α,β-ethylenically unsaturated carboxylic acid salt from the reaction medium comprises a liquid-liquid phase separation into
a first liquid phase in which the α,β-ethylenically unsaturated carboxylic acid salt is enriched, and
a second liquid phase in which the carboxylation catalyst, unconverted aryloxide and an arylhydroxide byproduct are enriched; and
the first and second liquid phases are obtained by contacting the reaction medium with a polar solvent.
24. The catalytic process according to claim 1 , further comprising regenerating the aryloxide by adding an alkaline material.