Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-02-19
2003-05-06
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S444000, C568S451000, C568S454000, C568S489000
Reexamination Certificate
active
06559344
ABSTRACT:
The present invention relates to a process for the hydroformylation of ethylenically unsaturated compounds, in which at least one complex or compound of a metal of transition group VIII with at least one bidentate phosphine ligand is used as hydroformylation catalyst and at least one of the reaction steps following the hydroformylation reaction is carried out essentially in the absence of carbon monoxide and hydrogen and in the presence of at least one monodentate phosphine ligand.
Hydroformylation or the oxo process is an important industrial process and is employed for preparing aldehydes from olefins, carbon monoxide and hydrogen. These aldehydes can, if desired, be hydrogenated by means of hydrogen to form the corresponding oxo alcohols in the same process. The reaction itself is exothermic and generally proceeds under superatmospheric pressure and at elevated temperatures in the presence of catalysts. Catalysts used are Co, Rh, Ir, Ru, Pd or Pt compounds or complexes which may be modified with N- or P-containing ligands to influence the activity and/or selectivity. The hydroformylation reaction results in formation of mixtures of isomeric aldehydes because of the possible addition of CO onto each of the two carbon atoms of a double bond. In addition, double bond isomerization, i.e. a shift of an internal double bond to a terminal position or vice versa, can occur.
Owing to the substantially greater industrial importance of the &agr;-aldehydes, optimization of the hydroformylation catalysts to achieve a very high hydroformylation activity combined with a very low tendency to form double bonds which are not in the &agr; position is desired. In addition, there is a need for hydroformylation catalysts which lead to good yields of not only &agr;-aldehydes but in particular n-aldehydes. For this purpose, the catalyst has to catalyze the hydroformylation of terminal olefins as selectively as possible.
The use of phosphorus-containing ligands for stabilizing and/or activating the catalyst metal in rhodium-catalyzed low-pressure hydroformylation is known. Suitable phosphorus-containing ligands are, for example, phosphines, phosphinites, phosphonites, phosphites, phosphoramidites, phospholes and phosphabenzenes. The most widely used ligands at present are triarylphosphines such as triphenylphosphine and sulfonated triphenylphosphine since these are sufficiently stable under the reaction conditions. However, these ligands have the disadvantage that, in general, only very high excesses of ligand give satisfactory yields, in particular of linear aldehydes. However, this generally reduces the activity.
In Tetrahedron Letters, volume 34, No. 13, page 2107 ff. (1993), in Tetrahedron Letters, volume 36, No. 1, page 75 ff. (1995) and in Chem. Ber. 124, page 1705 ff. (1991), Haenel et al. describe the synthesis of bis(diphenylphosphino)chelates having anthracene, dibenzofuran, dibenzothiophene and xanthene skeletons. Use of these compounds as catalysts is not described.
In J. Chem. Soc., Dalton Trans., 1998, pp. 2981-2988, W. Goertz et al. describe the use of chelating phosphines and phosphonites having a thioxanthene skeleton for the nickel-catalyzed hydrocyanation of styrene. Use in hydroformylation is not described.
In Organometallics 1999, 18, pages 4765 to 4777, van der Veen et al. describe the use of phosphacyclic diphosphines having a xanthene skeleton as ligands for rhodium-catalyzed hydroformylation. A disadvantage of these catalysts is their very low activity which makes use in industrial processes uneconomical.
WO 95/30680 describes bidentate phosphine ligands in which the phosphorus atoms can be bound to a xanthene skeleton and also describes the use of these ligands in catalysts for hydroformylation. A disadvantage of these catalysts is that they are not suitable for the isomerizing hydroformylation of internal olefins with good &agr;- or n-selectivity.
In Organometallics 1995, 14, p. 3081-3089, M. Kranenburg et al. describe the influence of the angle of bite of bidentate phosphine ligands on the regioselectivity of rhodium-catalyzed hydroformylation. Mixed complexes of monodentate and bidentate phosphine ligands were also prepared.
A disadvantage of bidentate phosphine ligands in general and bidentate phosphines having a xanthene skeleton in particular is that the catalytically active species formed from them under the conditions of the hydroformylation reaction are generally not stable in the absence of synthesis gas (CO/H
2
). It is generally not possible to convert catalyst species which have been deactivated in the absence of CO/H
2
back into an active hydroformylation catalyst. For this reason, continuous industrial hydroformylation processes which use catalysts based on bidentate phosphine ligands and encompass isolation of the hydroformylation products and recirculation of the catalyst can be implemented only with great technical difficulty, if at all. In any case, hydroformylation processes using such catalysts suffer from an economic disadvantage.
U.S. Pat. No. 4,169,861 describes a hydroformylation process for preparing 1-alkanals by hydroformylation of &agr;-olefins using a rhodium complex based on a monodentate ligand and a bidentate ligand as catalyst. trans-1,2-Bis(diphenylphosphinomethyl)cycloalkanes and 1,1′-bis(diphenylphosphino)ferrocenes are described as suitable bidentate ligands. U.S. Pat. No. 4,201,728 makes disclosures similar to those of U.S. Pat. No. 4,169,861. U.S. Pat. No. 4,201,714 relates to a rhodium catalyst as used for hydroformylation according to U.S. Pat. No. 4,201,728. According to the three last-named documents, the use of a catalyst based on a monodentate ligand and a bidentate ligand leads to an improvement in the n/iso product selectivity in the hydroformylation of &agr;-olefins. The use of monodentate phosphine ligands in highly selective hydroformylation catalysts based on bidentate phosphine ligands with the aim of stabilizing these catalysts even in the absence of synthesis gas is not described.
It is an object of the present invention to provide an improved process for the hydroformylation of compounds containing at least one ethylenically unsaturated double bond. The process should make it possible to separate off the desired products and recirculate the catalyst with very little drop in the activity of the catalyst used. The use of complicated measures for stabilizing the hydroformylation catalyst used when the desired products are separated off, possibly work-up of the catalyst before it is returned to the reaction, should preferably be able to be omitted. In particular, it should be possible to do without a synthesis gas atmosphere outside the reaction zone used for the hydroformylation. The hydroformylation of &agr;-olefins should preferably result in a very high proportion of &agr;-aldehydes or &agr;-alcohols. In particular, the process should also have a high selectivity to n-products.
We have found that this object is achieved by a hydroformylation process in which the hydroformylation catalyst used comprises at least one complex or compound of a metal of transition group VIII with at least one bidentate phosphine ligand and at least one of the reaction steps following the hydroformylation reaction is carried out essentially in the absence of carbon monoxide and hydrogen and in the presence of at least one monodentate phosphine ligand. The bidentate phosphine ligand used is preferably a compound in which the two phosphine groups are each bound to a different phenyl ring of a xanthene skeleton.
The present invention accordingly provides a process for the hydroformylation of compounds containing at least one ethylenically unsaturated double bond by reaction with carbon monoxide and hydrogen in the presence of a catalyst system comprising at least one metal of transition group VIII and at least one bidentate phosphine ligand, which comprises
(i) reacting the compound(s) containing at least one ethylenically unsaturated double bond in a reaction zone in the presence of carbon monoxide, hydrogen and the catalyst system,
(
BASF - Aktiengesellschaft
Keil & Weinkauf
Witherspoon Sikarl A.
LandOfFree
Hydroformylation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydroformylation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydroformylation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3042483