Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Patent
1988-10-26
1992-05-26
Garvin, Patrick P.
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
502155, 502164, 502204, 502206, 502209, 502210, 502211, 502215, 502227, 502228, 502242, 502243, 502246, 502248, 502254, 502255, 502305, 502308, 502309, 502311, 502312, 502317, 502318, 502321, B01J 3122
Patent
active
051167964
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates generally to organometallic complexes and their use in homogeneous catalysis, and more specifically to novel covalently bonded iridium-heteropolyanion species which are used as hydrogenation catalysts.
2. Background of the Invention
Catalysis by a bulk, oxide-supported metal two phase system, commonly referred to as heterogeneous catalysis, while generally producing high turnover frequencies and ease of product/catalyst separation, is plagued by a lack of chemical selectivity in addition to analytical difficulties in determining the chemical composition of the active site(s) as well as mechanistic details. Attempts to circumvent these short comings have primarily focused on chemically binding a discrete, well characterized organometallic moiety to a support, typically a polymer or silica substrate, thereby making the previously soluble organometallic complex insoluble and atomically dispersed. However, the usefulness of these "heterogenized" complexes as catalysts is limited by the same analytical difficulties associated with characterizing and doing mechanistic studies on bulk solid, two phase catalyst systems.
One recent report discloses a hydrogenation catalyst employing Rhodium and selected heteropolyanions (specifically Li.sub.4 SiW.sub.12 O.sub.40 and Li.sub.4 SiMo.sub.12 O.sub.40) (Urabe, K. et al., Chem. Lett., 1985, 1595). However, such polyoxoanions have zero surface charge and therefore are unable to covalently bond to and support an organometallic. Therefore, this polyoxoanion system is considered less desirable because it will not hinder Rh.sup.(0) formation in a Cl.sup.- and PPh.sub.3 -free system, nor will it prevent attachment of Rh.sup.I) to a cation exchange resin.
A different strategy is to synthesize soluble, oxide-supported organometallic catalyst precursors which could then be characterized and studied by employing a wide range of solution spectroscopic and kinetic methods. The present invention represents the first such examples of organic solvent soluble, atomically dispersed, oxide-supported catalyst precursors, covalently bonded iridium-heteropolyanions.
It is therefore an object of this invention to provide novel compounds wherein a covalent iridium-polyoxoanion bond remains stable under the conditions of catalytic hydrogenation.
It is a further object of this invention to provide catalyst systems which avoid Ir.sup.(1) formation under hydrogenation reaction conditions.
It is a further object of this invention to provide a catalyst system which can be readily and economically separated from the hydrogenation reaction mass by binding to an anion exchange resin.
It is a still further object of this invention to provide a catalyst system which is similar in chemical reactivity to atomically dispersed oxide-supported iridium complexes (e.g., Ir/Al.sub.2 O.sub.3) while being homogeneous and soluble.
It is still a further object of the present invention to provide a covalently bonded Ir.polyoxoanion system which will support the metal on the polyoxoanion in a Cl.sup.- and PPh.sub.3 -free system.
It is yet another object of the invention to provide a covalently bonded Ir.polyoxoanion system which will impede Ir.sup.(0) formation in a Cl.sup.- and PPh.sub.3 -free system.
It is yet another object of the invention to
provide a covalently bonded Ir.polyoxoanion system which will prevent attachment of Ir.sup.(1) to a cation exchange resin.
These and further objects of the invention will become apparent to those skilled in the art with reference to the description below.
SUMMARY OF THE INVENTION
The present invention provides novel liquid-phase olefin hydrogenation catalyst precursors which comprise either Dawson or Keggin structures represented in their ionic form by [L.sub.n Ir.sup.(1).X.sub.2 M.sub.15 M'.sub.3 O.sub.62 ].sup.x- and [L.sub.n Ir.sup.(1).XM.sub.9 M'.sub.3 O.sub.40 ].sup.y-, respectively. L represents a ligand chosen from 1,5-cyclooctadiene (COD), ethylene, cyclooctene, norbornadiene and other olefinic ligands; n=1 or 2
REFERENCES:
patent: 4294989 (1981-10-01), Knowles et al.
patent: 4720474 (1988-01-01), Vasilevskis et al.
patent: 4853357 (1989-08-01), Vasilevskis et al.
Urabe et al, Chem. Letters, 1985 pp. 1595-1596.
Edlund David J.
Finke Richard G.
Saxton Robert J.
Garvin Patrick P.
The University of Oregon
Wheelock E. Thomas
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