Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Patent
1991-02-06
1992-06-02
Prescott, Arthur C.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
556 16, 556 20, 556 27, 556 28, 556 51, 556 81, 556110, 556118, 556136, 204 59QM, 568429, C07F 1500, C07F 902
Patent
active
051188244
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to novel platinum hydrides, a process for their preparation and their use as components of catalytic systems intended for the catalysis of chemical reactions, in particular the hydroformylation reactions of ethylenically unsaturated compounds.
A first object of the present invention consists of a novel class of platinum hydrides with a bridged bimetallic structure, represented by the general formula: ##STR3## wherein M is a metal of valence n, at least equal to 2, formula: ##STR4## in which R1, R.sub.2, R.sub.5, R.sub.6, identical or different, are chosen from among aliphatic or cycloaliphatic hydrocarbon radicals with 1 to 8 carbon atoms and aromatic hydrocarbon radicals with 6 to 10 carbon atoms, hydrogen atom and aliphatic hydrocarbon radicals with 1 to 8 C atoms, possibly functionalized and/or together forming a ring, and
In Formula (I) the platinum hydrides according to the invention, X preferentially is chlorine, n is preferably equal to 2 or 3 and the metal M is preferably chosen from the groups IVB, VIII, IB, IIB, IIIA and IVA of the periodic classification. Even more preferably, M may be chosen from among iron (II), zinc, tin, copper, aluminum and titanium (III).
In the ligand formula (II), it is preferable that R.sub.1 =R.sub.5 and R.sub.2 =R.sub.6, and more particularly R.sub.1 =R.sub.2 =R.sub.5 =R.sub.6. As examples the following radicals may be cited: methyl, ethyl, isopropyl, tertiobutyl, neopentyl, cyclohexyl, phenyl, etc. If the R.sub.3 and R.sub.4 are functionalized, they may carry in particular a function such as thiol, alcohol, thioether, amine, imine, acid, ester, amide or ether.
An even more preferred class of ligands is that represented by the general formula: with 1 to 8 C atoms and aromatic hydrocarbon radicals with 6 to 10 C atoms, possibly functionalized (the function carried being as mentioned above), and
Examples of such ligands are in particular (1S, 2S)(+)trans-1,2-bis(diphenylphosphinometal)cyclohexane, 1,4-bis(diphenylphosphino)-butane and isopropylidene-dihydroxy-2,3-bis-(diphenylphosphino)1,4-butane.
The platinum hydrides according to the invention may be prepared by a number of processes. A first process comprises: alkylene carbonate in an electrochemical cell, the anode of which is a metal M, so as to form a chemical combination between the metal M and the alkylene carbonate, then formula ##STR5## wherein C and ##STR6## have the abovementioned significance and finally in a last stage the application of a hydrogen atmosphere.
The process therefore comprises, in a first stage, the formation of a chemical combination between the metal M and an alkylene carbonate which may be chosen in particular from among propylene, ethylene, 1,2-butylene and 1,2-hexylene. According to a particular embodiment of the process, the reduction of the solvent may be carried out in the presence of a small quantity of a conducting salt soluble in said solvent, such as for example tetra-n-butylammonium hexafluorophosphate. The presence of this conducting salt makes it possible to advantageously accelerate the reaction of the solvent, in particular at moderate temperatures. The electrochemical reduction phase according to the invention is generally carried out at a temperature between about 10.degree. and 70.degree. C., while maintaining the electrochemical cell under an inert gas atmosphere, such as for example nitrogen, argon or carbon monoxide; it is preferable in view of future uses of the platinum hydrides prepared in this manner, particularly as components of catalytic systems for chemical reactions, that the electrochemical reaction be carried out in the absence of hydrogen. The electrochemical solvent used in this stage of the process necessarily contains at least one alkylene carbonate, such as defined above. It may further contain, in a mixture with the former, another solvent, such as for example an aromatic hydrocarbon (benzene, toluene, xylene, etc.). To carry out the process of the invention it is preferred to use a solvent comprising at least about 10% by
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Brown et al, Jrnl. of Organometallic Chemistry, vol. 236, pp. C33-C36, (1982).
Mortreuz Andre
Paumard Eric
Petit Francis
Atochem
Prescott Arthur C.
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