Methoxycarbonylation with formic acid as CO source
View Patent ↗A catalytic process for the methoxycarbonylation of olefins where formic acid is the CO source. The process includes the steps of forming a reaction mixture where methanol and formic acid are added at a volume ratio in the range from 1.55:0.45 to 1.1:09. The methanol-formic acid ratio enhances both the rate of conversion and methyl ester yield ether produced. The catalysts used is a palladium/benzene-base diphosphine ligand complex.
1. A process for the methoxycarbonylation of olefins to form methyl esters comprising the process steps of:
a) adding an olefin to form a reaction mixture;
b) introducing to the mixture a compound comprising Pd, wherein the Pd is capable of forming a complex;
c) introducing to the mixture a compound of general formula (I):
wherein R 1 , R 2 , R 3 , R 4 are each independently selected from: —H, —(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl, —(C 4 -C 14 )-aryl, —O—(C 4 -C 14 )-aryl, cycloalkyl, —(C 1 -C 12 )-heteroalkyl, —O—(C 1 -C 12 )-heteroalkyl, —(C 3 -C 14 )-heteroaryl, —O—(C 3 -C 14 )-heteroaryl, —COO-alkyl, —COO-aryl, —C—O-alkyl, —C—O-aryl, NH 2 , and halogen;
wherein the recited alkyl groups, aryl groups, cycloalkyl, heteroalkyl groups, heteroaryl groups may be substituted as follows:
—(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl, halogen;
and at least one of the radicals R 1 , R 2 , R 3 , R 4 does not represent phenyl;
d) introducing to the mixture MeOH and HCOOH,
wherein the MeOH/HCOOH ratio based on the employed volume is in the range from 1.55:0.45 to 1.1:0.9;
e) heating the reaction mixture to convert the olefin into the methyl ester.
2. The process according to claim 1 ,
wherein no CO gas is supplied to the reaction mixture.
3. The process according to claim 1 ,
wherein HCOOH serves as the only CO source for the reaction.
4. The process according to claim 1 ,
wherein the compound in process step b) is selected from:
Pd(acac) 2 , PdCl 2 , Pd(dba) 3 *CH 3 Cl (dba=dibenzylideneacetone), Pd(OAc) 2 , Pd(TFA) 2 , Pd(CH 3 CN)Cl 2 .
5. The process according to claim 1 ,
wherein the process comprises additional process step f):
f) addition of an acid.
6. The process according to claim 5 ,
wherein the acid is selected from: H 2 SO 4 , CH 3 SO 3 H, CF 3 SO 3 H, PTSA.
7. The process according to claim 1 ,
wherein the MeOH/HCOOH ratio based on the employed volume is in the range from 1.5:0.5 to 1.2:0.8.
8. The process according to claim 1 ,
wherein R 1 , R 2 , R 3 , R 4 are each independently selected from: —(C 1 -C 12 )-alkyl, —(C 4 -C 14 )-aryl, —O—(C 4 -C 14 )-aryl, cycloalkyl, —(C 1 -C 12 )-heteroalkyl, —O—(C 1 -C 12 )-heteroalkyl, —(C 3 -C 14 )-heteroaryl, —O—(C 3 -C 14 )-heteroaryl, —COO-alkyl, —COO-aryl, —C—O-alkyl, —C—O-aryl, NH 2 , halogen and the residues are also capable of forming a larger condensed ring;
wherein the recited alkyl groups, aryl groups, cycloalkyl, heteroalkyl groups, heteroaryl groups may be substituted as follows:
(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl, halogen;
and at least one of the radicals R 1 , R 2 , R 3 , R 4 does not represent phenyl.
9. The process according to claim 1 ,
wherein R 1 , R 2 , R 3 , R 4 are each independently selected from: —(C 1 -C 12 )-alkyl, —(C 4 -C 14 )-aryl, cycloalkyl, —(C 1 -C 12 )-heteroalkyl, —(C 3 -C 14 )-heteroaryl, halogen and the residues are also capable of forming a larger condensed ring;
wherein the recited alkyl groups, aryl groups, cycloalkyl, heteroalkyl groups, heteroaryl groups may be substituted as follows:
—(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl, halogen;
and at least one of the radicals R 1 , R 2 , R 3 , R 4 does not represent phenyl.
10. The process according to claim 1 ,
wherein R 1 , R 2 , R 3 , R 4 are each independently selected from: —(C 1 -C 12 )-alkyl, cycloalkyl, —(C 3 -C 14 )-heteroaryl and the residues are also capable of forming a larger condensed ring;
wherein the recited alkyl groups, cycloalkyl, heteroaryl groups may be substituted as follows:
—(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl, halogen,
and at least one of the radicals R 1 , R 2 , R 3 , R 4 does not represent phenyl.
11. The process according to claim 1 ,
wherein R 1 , R 4 are each independently selected from: —(C 1 -C 12 )-alkyl, cycloalkyl and the residues are also capable of forming a larger condensed ring;
wherein the recited alkyl groups, cycloalkyl may be substituted as follows:
—(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl, halogen.
12. The process according to claim 1 ,
wherein R 2 , R 3 each independently represent —(C 3 -C 14 )-heteroaryl,
wherein the recited heteroaryl groups may be substituted as follows:
—(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl, halogen.
13. The process according to claim 1 ,
wherein the compound of general formula (I) has the structure (2):
14. The process according to claim 1 ,
wherein the compound of general formula (I) has the structure (3):