Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1997-09-12
1999-10-19
Owens, Amelia
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
502167, 502200, C07D30300
Patent
active
059691662
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to compounds which selectively catalyze the epoxidation of olefins with atmospheric oxygen, a process for their preparation and a process for the preparation of epoxides by catalytic oxidation of olefins with air or oxygen.
Epoxides (oxiranes), such as, for example, ethylene oxide, propylene oxide, 1,2-butene oxide or similar epoxides, are customary intermediate products for the preparation of a large number of products. The oxirane function in such compounds is very readily reacted, ring-opening reactions taking place with nucleophilic reactants. Epoxides can thus be hydrolyzed, for example, to glycols, which are used as de-icing agents or as reactive monomers for the preparation of condensation polymers.
Polyether polyols prepared by ring-opening polymerization of epoxides are customary as intermediate products for the preparation of polyurethane foams, elastomers, coatings, sealing compositions or similar articles.
The reaction of epoxides with alcohols leads to glycol ethers which are used, for example, as polar solvents.
Many different processes which are said to catalyze the epoxidation of alkenes selectively have been developed for the preparation of epoxides.
Thus, for example, Huybrecht (J. Mol. Catal. 71, 129 (1992); EP-A-311 983) describes the epoxidation of olefins with hydrogen peroxide in the presence of titanium silicate compounds as a catalyst. However, the range of products which is obtained during oxidation of alkenes with titanium silicate catalysts can be controlled only inadequately, so that even minimal changes in the reaction conditions or the reactants employed lead to drastic changes in the proportions of the end products.
The epoxidation of propylene with atmospheric oxygen in the presence of tungsten- or molybdenum-containing catalysts is described in DE-C-22 35 229. The epoxidation reaction is carried out in a solvent which can be oxidized with oxygen to form hydroperoxides. However, in secondary reactions, the hydroperoxides formed lead to oxygen-containing by-products, as a rule alcohols, which are obtained as coupling products of the reaction.
A process for the epoxidation of ethylene with t-butyl hydroperoxide (TBHP) in the presence of molybdenum complexes as the catalyst is described by Kelly et al. (Polyhedron, Volume 5, 271-275 (1986)). Compounds of high catalyst activity which are mentioned are complexes such as, for example, MoO.sub.2 (8-hydroxyquinoline).sub.2, MoO.sub.2 (phenylene-bis-salicylimine) (.dbd.MoO.sub.2 (salphene)), MoO.sub.2 (salicylaldoxime).sub.2 and MoO.sub.2 (5-nitroso-8-hydroxyquinoline).sub.2. The catalyst which is actually active is a molybdenum complex which has already added on TBHP and one equivalent of epoxide.
Although the process proceeds with a high selectivity, an expensive oxidizing agent is used. Problems furthermore arise in respect of the reproducibility, which prevents industrial use of the process.
It is furthermore known that certain ruthenium complexes are capable of reacting olefins with molecular oxygen to give the corresponding epoxide.
The ruthenium complex trans-(Ru(VI)(L)O.sub.2).sup.2+ where the ligand L.dbd.N,N-(dimethyl-N, N-)bis(2-pyridylmethyl)propylenediamine thus epoxidizes olefins, but only stoichiometrically. Norbornene is converted into 2,3-epoxynorbornane with a yield of 85%. Styrene is epoxidized to the extent of 56% and converted into benzaldehyde with a yield of 39%. On the other hand, cyclohexene is converted into the corresponding ketone without epoxide formation (J.Chem. Soc. Dalton Trans, 1990, 3735).
Conversion of norbornene into the corresponding epoxide is achieved catalytically with the complex cis-dioxo-ruthenium(VI)-bis(dimethyl-phenanthroline)-hexafluorophosphate. After an induction period of 24 hours, 37 catalysis cycles are found after a further 24 hours (J.Chem. Soc. Dalton Trans. 1987, 179).
According to Catal. Org. Reactions (47 (1992), pages 245-248), the two Ru complexes trans-dioxo(5,10,20-tetrakis(2,4,6,trimethylphenyl)[lacuna]-porphyrinato)r uthenium(VI) are capab
REFERENCES:
patent: 3668227 (1972-06-01), Scharbert et al.
patent: 5364952 (1994-11-01), Spiess et al.
Herrmann Wolfgang Anton
Lobmaier Gerhard
Scharbert Bernd
Hoechst Aktiengesellschaft
Owens Amelia
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