Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-02-25
2004-06-29
Wilson, James O. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C560S115000, C564S012000, C564S057000, C564S084000, C564S217000, C564S444000
Reexamination Certificate
active
06756500
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a process for preparing cyclic and/or polymeric compounds by metathesis of starting materials that contain at least two functional groups in the form of substituted or unsubstituted alkene or alkyne units.
For the purposes of the present invention, the term “metathesis” refers to a mutual transalkylidenation of alkenes and alkynes in the presence of catalysts. Reactions of this type are employed in many industrially important processes. A review may be found in: M. Schuster, S. Blechert, Angew. Chem. 1997, 109, 2124 and S. Armstrong, J. Chem. Soc., Perkin Trans. 1, 1998, 371. Metathesis reactions include the oligomerization and polymerization of acyclic dienes (ADMET) and the synthesis of carbocycles and heterocycles having various ring sizes by ring closing metathesis (RCM). Crossed metatheses of different alkenes are also known (Brümmer, O. et al. Chem. Eur. J. 1997, 3, 441).
For the above-mentioned metathesis reactions, it is possible to use the ruthenium-alkylidene compounds described in WO-A-93/20111, the ruthenium-based catalyst systems described by A. W. Stumpf, E. Saive, A. Deomceau and A. F. Noels in J. Chem. Soc., Chem. Commun. 1995, 1127-1128, or the catalyst systems described by P. Schwab, R. H. Grubbs and J. W. Ziller in J. Am. Chem. Soc. 1996, 118, 100 (see also WO 96/04289) as catalysts.
The use of nonaqueous ionic liquids for metathesis reactions has recently been described. These ionic liquids are salts or mixtures of salts that are liquid over a wide temperature range. The advantage of ionic liquids is that they are immiscible with aliphatic hydrocarbons. In organic reactions for which the use of a catalyst is necessary, heterogeneous catalysis can be achieved by addition of ionic liquids and a suitable catalyst that dissolves only or preferentially in the ionic liquid.
U.S. Pat. No. 5,104,840 describes the use of such mixtures as solvents for transition metal complexes, especially nickel complexes that contain no carbon-nickel bonds.
EP-B-448445 describes the use of ionic liquids for the dimerization of unsubstituted monoolefins using nickel chloride. However, a disadvantage here is the use of organoaluminium halide, especially the pyrophoric dichloroethylaluminium, for preparing the ionic liquid.
U.S. Pat. No. 5,525,567 describes the use of ionic liquids for the disproportionation of unsubstituted monoolefins using tungsten catalysts. Here too, it is necessary to use an organoaluminium halide, preferably the pyrophoric dichloroethylaluminium, for preparing the ionic liquid.
EP-A-882691 describes the use of ionic liquids for the dimerization of unsubstituted monoolefins in the presence of nickel chloride. Apart from the pyrophoric dichloroethylaluminium that is used here too, a further disadvantage is that the excess of the Lewis acid aluminium chloride in the ionic liquid results in an acidic reaction mixture.
The above-described metathesis processes are, moreover, suitable only for the reaction of unsubstituted monoolefins, i.e. very simple organic molecules. These processes are not suitable for the reaction of multiply substituted starting materials bearing functional groups, since the catalysts described there cannot be employed or the ionic liquids are unsuitable for other catalysts because of their composition or the fact that the reaction mixture has an acidic character.
It is an object of the present invention to provide a universally usable process for the metathesis of starting materials that contain at least two functional groups in the form of alkene or alkyne units that is carried out using ionic liquids. The process should also be able to be used for substituted alkenes or alkynes.
SUMMARY OF THE INVENTION
The invention, meeting the above-named object, provides a process that subjects starting materials that contain at least two functional groups in the form of alkene or alkyne units to metathesis. The process is carried out using ionic liquids. Advantageously, the process can be used for substituted alkenes or alkynes. These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims.
DESCRIPTION OF THE INVENTION
We have found a process for preparing cyclic and/or polymeric compounds by metathesis of starting materials that contain at least two functional groups in the form of substituted or unsubstituted alkene or alkyne units in the presence of one or more homogeneous or heterogeneous catalysts, wherein the metathesis is carried out in the presence of ionic liquids and the catalysts used are transition metal carbenes or transition metal compounds that form transition metal carbenes under the reaction conditions or transition metal salts in combination with an alkylating agent.
It has surprisingly been found that the presence of ionic liquids in the metathesis reaction of starting materials that contain at least two functional groups in the form of substituted or unsubstituted alkene or alkyne units leads to an increase in the operating life of the catalyst since it can be used in the ionic liquid for further metathesis reactions.
In a preferred embodiment, the present invention makes it possible to prepare carbocyclic or heterocyclic compounds having ring sizes of ≧5 ring atoms, including medium-sized rings (from 8 to 11 ring atoms) and large rings (≧12 ring atoms) and/or polymeric compounds that can be homopolymers, copolymers or block copolymers.
In ring closing metathesis reactions, the ring-closure reaction competes with polymerization. If this reaction is carried out using starting materials that contain at least two functional groups in the form of alkene or alkyne units, it results in mixtures of cyclic compounds and polymers.
The formation of cyclic compounds is favoured by carrying out the reaction in organic solvents at high dilution or by addition of relatively large volumes of ionic liquids. This applies particularly to the preparation of medium-sized rings (from 8 to 11 ring atoms) and large rings (≧12 ring atoms).
The large reaction volumes of organic solvents required to achieve the necessary high dilution limit the maximum space-time yields. Separating off the products after the reaction is complete requires time-consuming separation operations such as chromatography and usually leads to irreversible deactivation of the catalyst used.
The use of relatively large volumes of ionic liquids does, however, allow the desired products to be separated off easily, since they are present in the organic phase that is not miscible with the ionic liquid. If a catalyst that dissolves exclusively or preferentially in the ionic liquid is selected, the deactivation of the catalyst after the work-up can be avoided and the phase comprising the ionic liquid and the catalyst can be used for further metathesis reactions.
In the process of the invention, preference is given to using starting materials that contain, apart from the functional groups participating in the metathesis reaction, at least one further substituent that is inert in the metathesis reaction and/or a heteroatom. These substituents or heteroatoms can be selected independently from among: branched or unbranched alkyl radicals, aromatic or nonaromatic carbocyclic rings, carboxylic acids, esters, ethers, epoxides, silyl ethers, thioethers, thioacetals, anhydrides, imines, silylenol ethers, ammonium salts, amides, nitriles, perfluoroalkyl groups, geminal dialkyl groups, alkynes, alkenes, halogens, alcohols, ketones, aldehydes, carbamates, carbonates, urethanes, sulphonates, sulphones, sulphonamides, nitro groups, organosilane units, metal centres and oxygen, nitrogen, sulphur and/or phosphorus-containing heterocycles.
The process of the invention is particularly preferably carried out using, as starting materials, &agr;,&ohgr;-dienes that may contain at least one further substituent that is inert in the metathesis reaction and/or a heteroatom. These substituents or heteroatoms may be selected independently from a
Gürtler Christoph
Jautelat Manfred
Akorjt Godifled E.
Bayer Aktiengesellschaft
Eyl Diderico van
McKenzie Thomas
Wilson James O.
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