Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Patent
1998-05-22
2000-10-31
Bell, Mark L.
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
502150, 502152, 502155, 502156, 502168, 502208, 502213, 502216, 502223, 558357, B01J 3100, B01J 2714, B01J 27186, B01J 27187, C07C25500
Patent
active
061402656
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a palladium catalyst comprising a water-soluble phosphine ligand, preferably for carrying out cross-coupling reactions, a process for its preparation and also its use in cross-coupling reactions.
Cross-coupling reactions of aromatic boron compounds, e.g. boronic acids, and aromatic halogen compounds or perfluoroalkylsulfonates have for some years been used to an increasing extent for building up polycyclic aromatic systems. For example, such processes are used for producing active compounds for pharmaceuticals and components of liquid crystal mixtures.
However, the catalysts customarily used, e.g. Pd[P(Ph.sub.3)].sub.4 or PdCl.sub.2 (4PPh.sub.3)4NaBH.sub.4, give the coupling products in appreciable yields only when bromoaromatics or iodoaromatics are employed. The high costs of these starting compounds make economical scale-up of the processes to a production scale difficult.
EP-A 0 372 313 discloses palladium catalysts comprising water-soluble phosphine ligands which are used, for example, in the cross-coupling reaction of alkynes with allenes.
The systems described always contain palladium in the oxidation state (0).
EP-A 0 694 530 describes a process for preparing polycyclic aromatic compounds by cross-coupling aromatic boron compounds with aromatic halogen compounds or aromatic perfluoroalkylsulfonates using palladium catalysis in the presence of at least one water-soluble complexing ligand, wherein the reaction medium comprises an aqueous phase and an organic phase and the palladium is added in the form of a palladium compound soluble in the organic phase.
Although very good results are achieved using this process, there is still room for improvements, particularly with regard to the use of inexpensive chloroaromatics as starting material.
It has now surprisingly been found that palladium catalysts having a particularly high activity can be prepared by reaction of palladium(II) compounds, water-soluble phosphine ligands and a sulfoxide or a polyhydric alcohol.
The present invention accordingly provides a catalyst system, in particular for carrying out cross-coupling reactions, obtainable by-reacting
The invention further provides a process for preparing a catalyst system, in particular for carrying out cross-coupling reactions, which comprises reacting
The invention likewise provides for the use of a catalyst system obtainable by reacting reactions.
Catalyst systems according to the invention have a particularly high activity and it is possible to use them a plurality of times. They are also suitable, in particular, for coupling reactions in which chloroaromatics can be used as starting materials.
Suitable components a are palladium(II) compounds, preferably palladium(II) salts, tetrachloropalladic acid or its salts, preferably alkali metal salts. Preferred compounds are, for example, palladium acetylacetonates, palladium halides, allylpalladium halides and palladium biscarboxylates, particularly preferably palladium acetylacetonates, palladium(II) halides, tetrachloropalladic acid and its salts.
Compounds which are very particularly suitable as component a are Pd(II)Cl.sub.2 /3 NaOAc, Pd(ac).sub.2, K.sub.2 PdCl.sub.4, Na.sub.2 PdCl.sub.4, K.sub.2 Pd.sub.2 Cl.sub.6, Na.sub.2 Pd.sub.2 Cl.sub.6 and H.sub.2 PdCl.sub.4.
It is naturally also possible to use mixtures of two or more palladium compounds as component a.
In a preferred embodiment of the invention, the catalyst system comprises one or more additives such as sodium acetate which act as solubilizer for the palladium compound in the system sulfoxide or polyhydric alcohol and, if desired, water. Particular preference is given to using sodium acetate, in particular in a molar ratio of from 1 to 4, preferably 3, based on the palladium compound.
Suitable water-soluble phosphine ligands are tri-n-alkylphosphines, triarylphosphines, dialkylarylphosphines, alkyldiarylphosphines and heteroarylphosphines preferably provided with carboxylate or carboxylic acid, ammonium, phosphonium, sulfonate or sulfonic acid, phosphonate or phospho
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International Search Report.
Derwent Abstract--DE 19527118, May 16, 1997.
Derwent Abstract--DE 19535528, Nov. 20, 1997.
Derwent Abstract--DE 19620023, Nov. 25, 1997.
Egger Norbert
Haber Steffen
Bell Mark L.
Clariant GmbH
Dearth Miles B.
Hailey Patricia L.
Hanf Scott E.
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