Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-12-08
2001-08-07
Keys, Rosalynd (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S627000, C568S632000, C568S633000, C568S650000, C568S651000, C568S654000, C568S657000, C568S673000, C568S675000, C568S690000, C502S152000, C502S155000
Reexamination Certificate
active
06271423
ABSTRACT:
The present invention relates to a process for preparing butenyl ethers by addition of alcohols onto butadiene in the presence of transition metal complex catalysts containing ligands whose complex-forming centers are joined to a ferrocene cyclopentadienyl radical via atoms of group V of the Periodic Table of the Elements. WO 95/19334 comprehensively describes the preparation of butenyl ethers as intermediates for preparing n-butyraldehyde or n-butanol in the presence of complex catalysts. The process described there opens up a new route for the preparation of n-butyraldehyde and n-butanol compared to the synthesis by means of hydroformylation of propylene generally carried out in industry.
The new process provides a valuable alternative particularly where cheap butadiene is available as starting material.
Although WO 95/19334 has already described a large number of complex catalysts which are suitable for the new preparation of butenyl ethers and enable the industrial synthesis to be carried out in an economically satisfactory yield, certain features are still worthy of improvement.
It is an object of the present invention to provide further improvements, particularly in the combination of the features:
activity and selectivity of the catalyst in respect of the preparation of the desired butenyl ether of the formula I
CH
3
—CH═CH—CH
2
—OR I,
little formation of telomeric by-products and
easy preparation of the ligand of the complex catalyst.
We have found that this object is achieved by a process for preparing butenyl ethers of the formula I
CH
3
—CH═CH—CH
2
—OR I
by reacting butadiene or butadiene-containing hydrocarbon streams with alcohols of the formula II
ROH II
at elevated temperature and superatmospheric pressure in the presence of homogeneously dissolved transition metal complexes containing ligands of compounds of elements of group V of the Periodic Table of the Elements to form an isomer mixture of butenyl ethers of the formula I and butenyl ethers of the formula III
CH
2
═CH—CH (OR)—CH
3
III
and, if desired, isomerizing the butenyl ethers of the formula III to butenyl ethers of the formula I, where in each case R is an alkyl or alkenyl group having from 1 to 20 carbon atoms, an aryl group having from 6 to 10 carbon atoms or an aralkyl group having from 7 to 11 carbon atoms and the radicals R may be sub-stituted by hydroxy or alkoxy groups, wherein the catalyst used is a complex of a transition metal of group VIII of the Periodic Table of the Elements with ligands of the formula IV
where M is an iron, cobalt, nickel or ruthenium atom, X is a bridge in the form of a substituted or unsubstituted methylene group or an alkyl-substituted silylene group, where n is from 0 to 3, R
1
to R
4
are, independently of one another, also independently of one another in the two cyclopentadienyl radicals, hydrogen or alkyl, cycloalkyl, aryl or aralkyl radicals having up to 40 carbon atoms, preferably hydrogen or alkyl radicals having from 1 to 4 carbon atoms, or can be part of an isocyclic or heterocyclic ring system, where the two cyclopentadienyl radicals can also be bridged to one another via the respective radicals R
1
to R
4
, Y is nitrogen, arsenic, antimony or phosphorus and the radicals R
5
and R
6
are, independently of one another, also independently of one another in the two molecules of the sandwich complex, hydrogen or alkyl, cycloalkyl, aryl or aralkyl radicals having up to 24, preferably from 1 to 10, carbon atoms.
Particularly suitable transition metals of group VIII of the Periodic Table of the Elements are nickel and especially palladium.
The complexes can either be produced in situ in the reaction mixture or be preformed and added to the reaction mixture. To produce these complexes in situ, the procedure is generally to introduce the compounds of the transition metals, eg. their halides, preferably their chlorides, bromides or iodides, the nitrates, cyanides or sulfates or preferably complexes of these metals, eg. acetylacetonates, carboxylates, carbonyl complexes or olefin complexes such as ethene or butadiene compleses, together with the ligands into the reaction mixture, whereupon the complexes form in the reaction mixture.
In this procedure, palladium is generally used in the form of palladium dichloride, (dibenzonitrile)palladium dichloride, (diacetonitrile)palladium dichloride and preferably as palladium diacetate and palladium di(acetylacetonate).
Otherwise, the formation of the catalyst occurs in a manner known per se, with the ratio of ligand to palladium being selected in the range from 0.5 to 50, preferably from 1 to 20 and particularly preferably from 2 to 10.
The amount of palladium or the palladium-containing compound is generally from 0.001 to 5% by mass, preferably from 0.01 to 1% by mass, particularly preferably from 0.05 to 0.5% by mass, based on 1,3-butadiene used.
In particular, the ligands of the formula IV to be used according to the present invention contain iron as central atom of the sandwich complex. The substituents R
1
and R
4
are preferably hydrogen, the value of n is preferably 0 and Y is preferably phosphorus. The radicals R
5
and R
6
are, in particular, low molecular weight alkyl radicals, cyclohexyl radicals and phenyl radicals. Accordingly, the following individual ligands are found to be useful: 1,11′-bis(diphenylphosphino)ferrocene, 1,1′-bis(diisopro-pylphosphino) ferrocane1,1′-bis(diethylphosphino)ferrocene, 1,1′-bis(dipropylphosphino)ferrocene, 1′-(diisopropylphosphino)-1′-(dipropylphosphino)ferrocene, 1-(diisopropylphosphino)-1′-(dicyclohexylphosphino)ferrocene and 1,1′-bis(dicyclohexylphosphino)ferrocene.
The preparation of the ligands of the formula IV is either known from the literature or is carried out by methods similar to those described by J. J. Bishop et al. in J. Organometal Chem. 27 (1971) 241-249 and Ian R. Butler et al. in Synth. React. Inorg. Met.-Org. Chem. 15 (1985), (1), 109-116.
The alcohols ROH can in principle be any alcohols depending on which butenyl ethers are to be prepared. However, if the object is to prepare n-butyraldehyde or n-butanol, low molecular weight alcohols and in particular n-butanol are advantageously used.
The addition catalyzed by the complexes to be used according to the present invention and the isomerization are carried out under the same conditions as are described in WO 95/9334. In the addition of the alcohol ROH onto 1,3-butadiene, the molar ratio of 1,3-butadiene/palladium is generally set at from 100:1 to 100,000:1, preferably from 200:1 to 2000:1 and particularly preferably from 400:1 to 1000:1. If the process is carried out continuously, this molar ratio is based on the steady-state 1,3-butadiene concentration in the liquid raction mixture.
In this process embodiment, the molar ratio of alcohol ROH/1,3-butadiene can be selected within wide limits and is generally not critical. For example, the alcohol to be added onto 1,3-butadiene can function not only as a reagent but also as a solvent for the complex catalyst. For this reason, the alcohol/1,3-butadiene molar ratio employed is generally from 1:1 to 10:1, preferably from 1:1 to 5:1 and particularly preferably from 1:1 to 3:1, where these figures are based on the steady-state 1,3-butadiene concentration in the liquid reaction mixture if the process is carried out continuously.
The addition of the alcohol ROH onto 1,3-butadiene is generally carried out in the liquid phase. In general, the catalyst is initially charged as a solution in the liquid reaction medium and 1,3-butadiene in liquid or gaseous form is introduced together with the alcohol into the reaction mixture. The reaction medium employed can be the alcohol to be added onto 1,3-butadiene or a solvent which is inert under the reaction conditions, preferably a high-boiling solvent. Suitable solvents are, for example, condensation products which can be formed during the course of the reaction, for example alkoxyoctadienes, alkoxydodecatrienes, also
BASF - Aktiengesellschaft
Keil & Weinkauf
Keys Rosalynd
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