Bidentate ligand, catalyst system containing such ligand and...

Details Bidentate ligand, catalyst system containing such ligand and... Bidentate ligand, catalyst system containing such ligand and...

2001-05-17

2003-10-28

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C556S018000, C502S162000, C502S167000, C560S204000, C560S233000, C560S239000, C562S519000, C568S008000, C568S012000, C568S451000

Reexamination Certificate

active

06639091

ABSTRACT:

This invention relates to a bidentate ligand of formula I,
Q
1
Q
2
V
1
—Q—V
2
Q
3
Q
4
  (I)
wherein V
1
and V
2
are independently P, As or Sb; Q
1
, Q
2
, Q
3
and Q
4
represent hydrocarbyl groups and R represents a bivalent bridging group. The invention further relates to a catalyst system containing such a bidentate ligand, a source of group VIII metal cations and a source of anions. Moreover, the invention relates to a process for the carbonylation of optionally substituted ethylenically or acetylenically unsaturated compounds by reaction with carbon monoxide and a coreactant in the presence of such a catalyst system.
BACKGROUND OF THE INVENTION
One commercially important carbonylation reaction using hydrogen as coreactant, is the hydroformylation of alkenes or alkynes, which are reacted with carbon monoxide and hydrogen in the presence of transition metal catalysts to form aldehydes and/or alcohols having one carbon atom more than the precursor alkene or alkyne.
Depending on catalyst, reaction conditions and substrates, the hydroformylation may proceed with varying selectivities to the several possible isomeric aldehydes or alcohols in varying yields, as side reactions occur to a smaller or larger extent. Generally only one isomeric product is preferred. For many applications the presence of branched aldehydes or alcohols is undesirable. Moreover, in view of biological degradability, it is considered advantageous to obtain products having a high content of the linear isomer. The selectivity towards one of several possible isomeric products is called regioselectivity. For hydroformylation a regioselectivity towards reaction at the primary carbon atom, resulting in a linear product, is desirable.
Another commercially important carbonylation reaction using an alkanol or water as coreactant, is the carbonylation of alkenes or alkynes, which are reacted with carbon monoxide and alkanol in the presence of Group VIII metal catalysts to form esters, diesters or carboxylic acids. An example of such a carbonylation is the reaction of ethene with carbon monoxide and butanol to prepare butylpropionates.
CA-A-2086285 relates to the preparation of diphosphines, wherein an alkane, alkene or arene is vicinally disubstituted with two organophosphino groups. The bidentate diphosphines are said to be useful in the preparation of catalysts for the preparation of polyketones. In example 13 the preparation of 2,3 bis(di-isobutylphosphino)pentane) is described.
WO 9505354 describes the hydroformylation of ethylenically unsaturated compounds by reaction with carbon monoxide and hydrogen in the presence of a catalyst system comprising a Group VIII metal cation, viz. cationic palladium, and a bidentate ligand, viz. a diphosphine. In the examples several bidentate diphosphines are used. As is illustrated by examples 46 and 47 the hydroformylation of 1-octene with a catalyst system containing a bidentate diphosphine results in acceptable selectivities towards the linear product. The results show that the use of a bidentate diphosphine having an unsubstituted bivalent organic bridging group, connecting both phosphorus atoms, i.e. 1,2-bis-(1,4-cyclooctylenephosphino)ethane, results in higher selectivities towards the linear product than the use of a bidentate diphosphine having a monosubstituted bivalent organic bridging group, connecting both phosphorus atoms, i.e. 1,2-bis(1,4-cyclooctylenephosphino)propane. Hence, this patent document suggests that non-substituted bridging groups are advantageous compared to substituted bridging groups.
Although good results with regard to this regioselectivity towards the linear product are obtained in WO 9505354, there is still room for improvement. This need especially exists with regard to smaller ethylenically unsaturated compounds, where side-reactions more readily occur.
Examples 28 to 36 of EP-A-0495547 describe a carbonylation of ethene with carbon monoxide and n-butanol in the presence of bidentate diphosphines having an unsubstituted bivalent organic bridging group, connecting both phosphorus atoms, i.e. 1,3-bis(di-isopropylphosphino)propane; 1,3-bis(di-ethylphosphino)propane; 1,3-bis(di-s-butylphosphino)propane, 1,3-bis-(di-phenylphosphino)propane. Selectivities of 98% and rates of conversion in the range from 100 to 1000 mol butylpropionate/mol Pd/hr are obtained.
Although good results with regard to selectivity and activity are obtained in EP-A-0495547, there is still room for improvement.
SUMMARY OF THE INVENTION
Accordingly this invention provides a bidentate ligand of formula II,
R
1
R
2
M
1
—R—M
2
R
3
R
4
  (II)
wherein M
1
and M
2
are independently P, As or Sb; R
1
, R
2
, R
3
and R
4
independently represent tertiary alkyl groups, or R
1
and R
2
together and/or R
3
and R
4
together represent an optionally substituted bivalent cycloaliphatic group whereby the two free valencies are linked to M
1
or M
2
, and R represents a bivalent aliphatic bridging group containing from 2 to 6 atoms in the bridge, which is substituted with two or more substituents.
Further, a catalyst system comprising
a) a source of group VIII metal cations,
b) a source of such a bidentate ligand, and
c) a source of anions is provided. A process for the carbonylation of optionally substituted ethylenically or acetylenically unsaturated compounds comprising reacting the unsaturated compounds with carbon monoxide and a coreactant in the presence of such a catalyst system is also provided.
DETAILED DESCRIPTION OF THE INVENTION
It has now surprisingly been found that when carbonylation is carried out in the presence of a catalyst system that is characterized by a specific choice of bidentate ligand containing a polysubstituted bridging group, unexpected advantages with regard to the regioselectivity and/or activity are obtained. It was found that a catalyst system comprising such a bidentate ligand having a polysubstituted bivalent aliphatic bridging group results in a high regioselectivity towards the linear product and/or a higher activity.
In the bidentate ligand of formula II, M
1
and M
2
are preferably the same and more preferably they both represent phosphorus atoms.
By “a bridge” is understood the shortest connection between the atoms M
1
and M
2
. This bridge can be saturated or non-saturated or can form part of an optionally substituted saturated or non-saturated aliphatic ring structure, comprising one or more rings. The bridge can further contain heteroatoms such as nitrogen, sulphur, silicon or oxygen atoms. Preferably at least the atoms in the bridge connected to M
1
and M
2
are carbon atoms, more preferably all atoms in the bridge are carbon atoms.
The bridge connecting M
1
and M
2
forms part of a bridging group R, which can be saturated or unsaturated and which can be an optionally substituted saturated or non-saturated aliphatic ring structure, such as for example cyclohexane, cyclohexene, cyclopentane or cyclopentene. The bridging group can further contain heteroatoms such as nitrogen, sulphur, silicon or oxygen atoms. Unsaturated bonds and/or heteroatoms can be present in each part of the bridging group R, both within and outside the bridge. If the bridging group R is a cycloaliphatic ring structure, the ring may be interrupted by one or more heteroatoms such as nitrogen, sulphur, silicon or oxygen atoms. The aliphatic ring structure can further be substituted with any kind of substituent, including heteroatoms, alkylgroups, cycloalkyl groups and aryl groups, both within as well as outside the bridge.
The bivalent aliphatic bridging group R, connecting the atoms M
1
and M
2
contains from 2 to 6 atoms in the bridge, more preferably 2 to 4 atoms, and most preferably 2 to 3 atoms. Preferably the atoms in the bridge are carbon atoms. Bivalent aliphatic bridging groups R, containing 2 carbon atoms in the bridge are especially preferred.
The bridge is substituted with at least two substituents. Preferably the bridge is substituted with two to four substituents and more preferably with two to three substituents. Most preferably the

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