Metal-compound catalyzed processes
A liquid-phase chemical reaction medium comprises one or more reactants, optionally in the presence of a reaction product(s) and one or more solvents, diluents or other form of liquid carrier, a catalyst system comprising at least a metal or metal compound and optionally further compounds such as ligands or complexing agents; characterized in that the reaction medium further comprises a polymeric dispersant dissolved in said liquid carrier, said polymeric dispersant being capable of stabilizing a colloidal suspension of particles of said metal or metal compound within the liquid carrier. The presence of the polymeric dispersant enables metal formed by catalyst deactivation to be more easily recovered and recycled. Preferably, the polymeric dispersant has sufficiently acidic or basic functionality to stabilize the colloidal suspension of said metal or metal compound.
1. A liquid-phase carbonylation reaction medium comprising one or more reactants, including a substrate selected from the group consisting of alkenes and alkynes, a carbonylation agent and a liquid carrier, for carbonylation of the said substrate, optionally comprising a reaction product(s); a catalyst system comprising at least a metal or metal compound and optionally further compounds such as ligands or complexing agents; characterised in that the reaction medium further comprises a polymeric dispersant dissolved in said liquid carrier, the dispersant comprising acidic or basic polymers and a colloidal suspension of particles of said metal or metal compound within the liquid carrier stabilized by the said polymeric dispersant, the polymeric dispersant having sufficient acidic or basic functionality to substantially stabilize a colloidal suspension of said metal or metal compound.
2. A liquid phase carbonylation reaction medium according to claim preceding 1 , wherein the acidic or basic functionality is provided by carboxylic acids, sulphonic acids, amines and/or amides.
3. A liquid phase carbonylation reaction medium according to claim 1 , wherein the polymeric dispersant is selected from the group consisting of polyvinylpyrrolidone, polyacrylamide, polyacrylonitrile, polyethylenimine, polyglycine, polyacrylic acid, polymethacrylic acid, poly(3-hydroxybutyricacid), poly-L-leucine, poly-L-methionine, poly-L-proline, poly-L-serine, poly-L-tyrosine, poly(vinylbenzenesulphonic acid) and poly(vinylsulphonic acid).
4. A liquid phase carbonylation reaction medium according to claim 1 , wherein the polymeric dispersant incorporates acidic or basic moieties either pendant or within the polymer backbone.
5. A liquid phase carbonylation reaction medium according to claim 4 wherein the acidic moieties have a dissociation constant (pK a ) of less than 6.0.
6. A liquid phase carbonylation reaction medium according to claim 4 , wherein the basic moieties have a base dissociation constant (pK b ) or less than 6.0.
7. A liquid phase carbonylation reaction medium as claimed in claim 1 wherein said polymeric dispersant is selected from the group comprising polyvinylpyrollidone (PVP) and polyacrylates.
8. A liquid phase chemical reaction medium as claimed in claim 1 comprising methanol, ethylene, methyl propionate and carbon monoxide in addition to a catalyst system comprising a palladium compound.
9. A process for the carbonylation of a substrate comprising the steps of
a. forming in a chemical reactor a liquid phase carbonylation reaction medium according to claim 1 ,
b. removing from said reactor a portion of said liquid phase carbonylation reaction medium,
c. separating said portion of liquid phase carbonylation reaction medium so as to remove from the liquid as a solid-phase colloidal metal particles formed by decomposition of the catalyst system, which are dispersed in the liquid phase by the polymeric dispersant;
d. optionally returning the liquid portion of said separated reaction medium to the reactor; and
e. optionally processing the recovered metal particles so as to form a further quantity of the catalyst system.
10. A process according to claim 9 wherein the catalyst system is a homogenous catalyst system.
11. A process according to claim 9 wherein the metal is a group VIII or group 1B metal.
12. A process according to claim 9 , wherein the catalyst system incorporates a phosphine ligand.
13. A process for the manufacture of an alkyl ester comprising the steps of:
a) forming in a chemical reactor a liquid phase carbonylation reaction medium comprising an alkyl alcohol, an olefin and carbon monoxide in the presence of a catalyst system comprising a metal compound and a ligand compound, optionally in the presence of the alkyl ester product and/or other solvents, co-catalysts and a polymeric dispersant which is dissolved in said liquid phase chemical reaction medium, said polymeric dispersant comprising acidic or basic polymers, said acidic or basic polymers having sufficient acidic or basic functionality to substantially stabilize a colloidal suspension of said metal compound or a metal derived from the metal compound, a stabilised colloidal suspension of particles of said metal compound or the metal of the metal compound within the liquid phase chemical reaction medium; at a temperature and pressure under which the olefin is alkoxy-carbonylated to form the alkyl ester product, and subsequent steps b)-e) according to claim 9 .
14. A process as claimed in claim 9 , wherein the liquid-phase reaction medium comprises ethylene and carbon monoxide dissolved in methanol and methyl propionate in the presence of a homogeneous catalyst system comprising a compound of palladium, an organic phosphine ligand and optionally, a source of anions; and said polymeric dispersant.
15. A process for the carbonylation of a substrate selected from the group consisting of alkenes and alkynes, comprising the step of: forming in a chemical reactor a liquid phase carbonylation reaction medium; characterised in that the reaction medium further comprises a polymeric dispersant dissolved in a liquid carrier, the dispersant comprising acidic or basic polymers, the polymeric dispersant having sufficient acidic or basic functionality to substantially stabilize a colloidal suspension of a metal or metal compound, and a colloidal suspension of particles of a said metal or metal compound within the liquid carrier stabilized by the said polymeric dispersant.
16. A process according to claim 15 , wherein the acidic or basic functionality is provided by carboxylic acids, sulphonic acids, amines and/or amides.
17. A process according to claim 15 , wherein the polymeric dispersants may be selected from polyvinylpyrrolidone, polyacrylamide, polyacrylonitrile, polyethylenimine, polyglycine, polyacrylic acid, polymethacrylic acid, poly(3-hydroxybutyricacid), poly-L-leucine, poly-L-methionine, poly-L-proline, poly-L-serine, poly-L-tyrosine, poly(vinylbenzenesulphonic acid) and/or poly(vinylsulphonic acid).
18. A process according to claim 15 wherein the polymeric dispersant incorporates acidic or basic moieties either pendant or within the polymer backbone.
19. A process according to claim 18 , wherein the asic moieties have a base dissociation constant (pK b ) iof less than 6.0.