Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-05-16
2002-05-14
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S451000
Reexamination Certificate
active
06388142
ABSTRACT:
The present invention relates to a process for the hydroformylation of olefinically unsaturated compounds having 3 to 12 carbon atoms with hydrogen and carbon monoxide at increased pressure.
In the hydroformylation of olefins with carbon monoxide and hydrogen aldehydes and alcohols are produced with the aldehydes and alcohols having one carbon atom more than the starting olefin. The catalyst is herein conventionally used in homogeneous phase with the olefin. The reaction is preferably catalyzed by hydridrometal carbonyles of the metals of group VIII of the periodic table of elements. Apart from cobalt, which is used extensively as a catalyst metal in technical applications, rhodium has acquired increasing significance preferably for the hydroformylation of lower olefins. In contrast to cobalt, rhodium permits carrying out the reaction at low pressure, moreover, when using terminal olefins preferably straight-chain n-aldehydes are formed and only secondary iso-aldehydes. Furthermore, the hydrogenation of the olefinic compounds to form saturated hydrocarbons in the presence of rhodium catalysts is also markedly lower than is the case when using cobalt catalysts.
In methods introduced in technology the rhodium catalyst is used in the form of modified hydridorhodium carbonyles, which additionally and, if appropriate, comprise ligands in excess. Especially useful have been found to be ligands of tertiary phosphines or phosphites. Their application permits lowering the reaction pressure to values below 30 MPa.
For example, DE 27 43 630 relates to the production of alkane polyols (glycols) from synthesis gas using a crown ether comprising at least 4 oxygen atoms as solvent. This crown ether serves for separating ions from the homogeneous liquid phase without the simultaneous complex formation of the rhodium-containing catalyst. The reaction temperatures in all examples are above 220° C.
In U.S. Pat. No. 4,320,064 is described the reaction of carbon monoxide with hydrogen to form polyols using rhodium carbonyl clusters in a homogeneous liquid phase. As the catalyst a cesium salt of [Rh
22
(CO)
35
H
x
]
n−
complexed by 18-crown-6 is used. Here also the crown ether serves for the complexing of the cationic component of the rhodium carbonyl cluster. The temperatures specified in the examples are between 250 and 270° C.
However, in these methods the separation of the reaction products and the recovery of the catalysts homogeneously dissolved in the reaction product presents problems. In general, for this purpose, the conversion product is distilled out of the reaction mixture. Due to the thermal sensitivity of the formed aldehydes and alcohols, this approach can only be followed in practice in the hydroformylation of short-chain olefins with 3 to 5 carbon atoms.
In the hydroformylation of olefins with more than 6 carbon atoms, products with high boiling point are formed which cannot be separated by distillation from the homogeneously dissolved rhodium complex catalyst. Through the formation of heavy oil, the thermal loading of the distillation material leads to considerable losses of valuable products and of catalysts through the decomposition of the rhodium complex compounds.
The problem of thermal decomposition is avoided if a two-phase catalysis is used. Herein two liquid phases not miscible with one another are present of which the one organic phase contains the olefin and the other, most often polar phase, contains the catalyst. Prerequisite for the application of this process is the solubility of the catalyst in the polar phase. On an industrial scale as the polar phase is used an aqueous phase and as the catalyst a rhodium complex compound. The solubility of the catalyst in the aqueous phase is herein attained by using sulfonated triaryl phosphines as complex component. After completing the hydroformylation reaction, the separation of the catalyst from the reaction product in this process variant takes place simply by separation of the aqueous and organic phase, i.e. without distillation and thus without additional thermal process steps. Such a process is described for example in DE 26 27 354. A special characteristic of this mode of operation is that from terminal olefins with high selectivity are formed n-aldehydes and only to a minor degree iso-aldehydes (i.e. aldehydes branched in the &agr; position to the aldehyde group). In addition to sulfonated triaryl phosphines, carboxylated triaryl phosphines are also used as complex components water-soluble rhodium complex compounds.
The use of a water-soluble catalyst has also been found to be useful in the hydroformylation of lower olefins, in particular propene and butene. However, if higher olefins such as pentene or hexene are used, the conversion rate is already markedly reduced. The economy of the conversion on an industrial scale is frequently no longer given to the desired extent when using olefins with more than four carbon atoms.
In order to increase in the hydroformylation of olefins with more than 5 carbon atoms by means of water-soluble catalysts the conversion and/or the selectivity of the reaction to n-aldehydes, special amphiphilic reagents or solubilizers have also been used.
The addition of these substances leads to the fact that the transport of matter between the discrete phases and thus the miscibility of the aqueous catalyst phases and organic phase are promoted.
DE 34 12 334, for example, relates to the hydroformylation of olefins using quaternary ammonium salts. As is evident in Table 4, the hydroformylation of hexene by means of rhodium and trisodium tris(m-sulfophenyl)phosphine without the addition of a solubilizer leads to a conversion of 36% (Example 10), while the addition of polyols as solubilizer (Example 11: 5% polyglycol 200; Example 14: 2.5% triethylene glycol) only brings about a conversion of 43.5% or 43%, respectively. A very high conversion, 86%, in contrast, is attained through the addition of 2.5% trimethyl hexadecyl ammonium bromide as solubilizer. This publication shows that only the addition of quaternary ammonium salts causes a considerable increase in the conversion. In contrast, neither the addition of tri- or polyglycols, not an increase of the quantity of these substances by the twofold (from 2.5 to 5%) causes a significant increase of the conversion.
In DE 31 35 127 A1 the hydroformylation of olefins is described using amphiphilic reagents in the presence of a rhodium catalyst complexed by a phosphine ligand. Table 7 shows that the hydroformylation of 1-dodecene by means of rhodium and monosulfonated triphenyl phosphine (3-Ph
2
PC
6
H
4
SO
3
Na) without the addition of an amphiphilic reagent leads to a conversion of 56% (Example 77), while the addition of 18-crown-6 leads to a decrease of the conversion to 40% (Example 57). In this case also high yields are only attained by using quaternary ammonium salts (Example 68: 85% with CTAB).
A substantial disadvantage in using quaternary ammonium salts as amphiphilic reagents lies, however, in their poor biological degradability. For example, the presence of quaternary ammonium salts in the waste water leads to considerable difficulties in waste water treatment.
A further disadvantage in using quaternary ammonium salts as solubilizers lies therein that the increase of the miscibility of the aqueous catalyst phase and the organic phase achieved with these compounds is accompanied by increased solubility of the organic phase in the aqueous phase and of the aqueous phase in organic phase. In this way, to an increasing degree amphiphilic reagent and solubilizer as well as also rhodium and water-soluble phosphines can be present in the organic phase and, after phase separation, can be discharged with the organic phase. It is understood that the discharge of these substances via the organic phase is undesirable since new substances must again be added to the same extent to the aqueous phase to the same extent, which, in particular in view of rhodium, entails considerable increased financial expenditures.
Furthermore, with a higher ad
Bogdanovic Sandra
Kuhlein Klaus
Bierman, Muserlian and Lucas
Celanese Chemicals Europe GmbH
Padmanabhan Sreeni
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