Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By alkyl transfer – e.g. – disproportionation – etc.
Reexamination Certificate
1999-06-21
2004-01-13
Dang, Thuan D. (Department: 1764)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By alkyl transfer, e.g., disproportionation, etc.
C585S646000, C585S647000
Reexamination Certificate
active
06677495
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to cyclopentene-derived oligomer mixtures, a process for their preparation by ring-scission metathesis and their use as intermediates for further processing by double-bond functionalization.
2. Description of the Related Art
In the processing of petroleum by steam crackers, a hydrocarbon mixture termed C
5
fraction is, produced, inter alia, which has a high total olefin content of, for example, about 50%, of which approximately 15% is made up of cyclopentene and the remainder of acyclic monoolefins, especially n-pentene (approximately 15% by weight) and other isomeric pentenes (approximately 20% by weight). This mixture can, if desired, prior to further processing, be subjected to a catalytic partial hydrogenation, so that dienes are then essentially no longer present. To isolate the cyclopentane which is present at about 8% in the C
5
fraction and is used for example as propellant as substitute for the CFCs and HCFCs which are of concern with regard to harm to the atmosphere, and, if appropriate, to isolate the remaining saturated acyclic pentenes, it is necessary according to the prior art to subject the C
5
fraction to work-up by distillation. This is highly complex in processing terms if acyclic and cyclic C
5
olefins, in particular cyclopentene, are simultaneously present. There is therefore a requirement for a process for removal of the cyclopentene other than by distillation, with or without other monoolefins, from the C
5
fraction, as far as possible with simultaneous production of a new product of value.
An industrially important olefin reaction which retains the number of C═C double bonds is metathesis. The term metathesis formally denotes the exchange of alkylidene groups between two alkenes in the presence of homogeneous or heterogeneous transition metal catalysts. A simple example of an industrially used metathesis reaction between two acyclic olefins is the conversion of propene to ethene and 2-butene.
The ring-scission polymerization of cyclic olefins, which proceeds by the metathesis mechanism, leads to poly-(1-alkenylenes), which are termed polyalkenamers. In contrast to the polymerization of vinyl compounds, in this case the double bonds of the monomer are retained in the polymer. The metathesis of acyclic and cyclic olefins is described, for example, by R. H. Grubbs in Progress in Inorganic Chemistry, John Wiley & Sons, New York, 1978, Vol. 24, pp 1-50; in Comprehensive Organomet. Chem., Pergamon Press, Ltd., New York, 1982, Vol. 8, pp. 499-551 and in Science (1989) 243, pp 907-915; and by D. S. Breslow in Prog. Polym. Sci. Vol. 18 (1993) pp. 1141-1195; by H. Höcker and H. Keul in Adv. Mater. 6 (1994) No. 1, pp. 21-36 and by G. Sundararajan in J. Sci. Indus. Res. Vol. 53 (1994) pp. 418-432.
R. R. Schrock, in Acc. Chem. Res. 23 (1990) pp. 158 ff., describes the mechanism of the ring-scission metathesis polymerization in accordance with the following scheme:
In this scheme, in the initiation step (1), a cycloolefin is first added to a metal carbene complex, with formation of a metallacyclobutane intermediate, which can either break down to reform starting materials, or can open to give a new carbene complex with chain elongation. The chain growth (propagation) (2) proceeds in the ideal case of the living ring-scission metathesis polymerization in such a manner that one polymer strand is formed per metal center, so that monodisperse polymers having a polydispersity of almost 1 are obtained. The chain termination (3), ie. the detachment of the polymer from the metal, is generally carried out by adding an acyclic olefin. Here, in the ideal case, it is possible both to exert a targeted influence on the chain length and to regenerate the catalyst. In the case of chain termination using a functionalized olefin, the functionality transfers to the end of the polymer chain.
BE-A-759774 describes a process for controlling the molar mass and molar mass distribution in ring-scission metathesis polymerization, in which, for example when a polyoctenamer is prepared, 1-pentene is used as acyclic olefin and thus chain-termination reagent.
By using acyclic olefins, firstly, the chain length may be controlled specifically in the ring-scission metathesis polymerization. Secondly, the ethenolysis of cyclic olefins, in which equimolar amounts of a cyclic olefin are reacted with ethene according to the following scheme:
serves in the preparation of &agr;,&ohgr;-unsaturated olefins which are otherwise difficult to synthesize.
U.S. Pat. No. 3,715,410 describes reacting cyclic olefins with acyclic olefins to give acyclic polyenes in the presence of what is termed an olefin disproportionation catalyst. Thus, by reacting cyclic monoolefins or non-conjugated polyolefins with ethene &agr;,&ohgr;-unsaturated acyclic diolefins or polyenes may be prepared. &agr;,&ohgr;-unsaturated diolefins can readily be converted to diols having terminal hydroxyls, and are used in the preparation of polyesters, for example. By reacting cyclic monoolefins with a substituted acyclic olefin, non-conjugated acyclic diolefins having one terminal double bond and one terminally substituted double bond are obtained, for example when cyclooctene is reacted with propene to give 1,9-undecadiene. These are used, for example, as monomers in homopolymerization or copolymerization in order to obtain polymers which may be readily crosslinked.
DE-A-2 047 270 describes a process for preparing a catalyst for the disproportionation of olefins based on organometallic compounds which contain a transition metal of subgroup 6 and a metal of main groups 1 to 3 of the Periodic Table of the Elements, preferably aluminum. The catalysts are suitable both for homo- and cross-disproportionations, in which a mixture of two different olefins is reacted with formation of a product mixture according to the following general scheme:
R
1
R
2
C═CR
3
R
4
+R
5
R
6
C═CR
7
R
8
⇄
R
1
R
2
C═CR
7
R
8
+R
1
R
2
C═CR
5
R
6
+R
3
R
4
C═CR
7
R
8
+R
3
R
4
C═CR
5
R
6
The disproportionation reactions described include:
1. The conversion of a mixture of one acyclic mono- or polyolefin and one cyclic mono- or polyolefin to an acyclic polyolefin of higher molecular weight.
2. The conversion of one or more cyclic mono- or polyolefins with formation of cyclic polyolefins of higher molecular weight.
3. The conversion of one or more acyclic polyolefin with formation of cyclic mono- or polyolefins and acyclic mono-or polyolefins.
DE-A-2 028 935 describes polyalkenamers, which are prepared by ring-scission metathesis polymerization from cyclic olefins and unsaturated esters having double bonds which are not situated in a ring, a catalyst system consisting of a tungsten compound or molybdenum compound and an organoaluminum compound as well as a compound which contains one or more hydroxyls and/or sulfhydryls being used.
DE-A-2 051 798 also describes a process for preparing polyalkenamers by ring-scission polymerization of cyclic olefins by means of catalyst consisting of:
a) Tungsten halides or tungsten oxyhalides containing hexavalent tungsten,
b) an organoaluminum compound,
c) a monocarboxylic acid soluble in the reaction mixture.
DE-A-2 051 799 also describes a process for preparing polyalkenamers by ring-scission polymerization of cyclic olefins using a catalyst system based on a hexavalent tungsten compound and an organoaluminum compound.
DE-A-3 529 996 describes a process for preparing polyalkenamers having an elevated cis content of the double bonds present in the polymer, prepared by ring-scission metathesis polymerization of cis,cis-cycloocta-1,5-diene or norbornene, the polymerization being carried out in the presence of an open-chain 1,3-diene, such as isoprene, or a cyclic 1,3-diene, such as cyclohlexa-1,3-diene.
DE-A-2 201 161 describes a process for preparing polymers from cycloolefins, preferably cyclopentene and cyclooctene, by ring-scission metathesis polymerization using a catalyst system consisting o
Höhn Arthur
Schäfer Martin
Schwab Peter
BASF - Aktiengesellschaft
Dang Thuan D.
Keil & Weinkauf
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