MXPA99005833A - Oligomer mixtures derived from cyclopentene;method for the production and use thereof - Google Patents

Abstract

The present invention relates to a method for the production of cyclopentene-oligomer mixtures of formula (I), characterized in that a hydrocarbon mixture containing acyclic monoolefins from an oil refining cracking process (C5-cut) and cyclopentene are transformed in a homogenous or heterogeneous catalyzed metathesis reaction. The invention also relates to cyclopentene oligomers of formula (I) which can be obtained according to said method, and the use thereof.

Description

MIXTURES OF OLIGOMETERS DERIVED FROM CYCLOPENTIN, ITS PREPARATION AND ITS USE The present invention relates to mixtures of oligomers derived from cyclopentene, a process for their preparation by ring-breaking metathesis and their use as intermediates for other processing by functionalization of the double bond. In the processing of the oil by steam fractionators, a mixture of hydrocarbons called C5 fraction, among others, having a high total olefin content of, for example, about 50%, of which about 15% is made up of cyclopentene and the rest of acyclic monoolefins, especially n-pentene (approximately 15% by weight) and other isomeric pentenes (approximately 20% by weight). This mixture can, if desired, before being subjected to further processing, be subjected to a catalytic partial hydrogenation, so that these dienes are practically no longer present. To isolate the cyclopentane that is present in about 8% in the C5 fraction and is used for example as a propellant as a substitute for the CFCs and HCF that are of interest with respect to the damage to the atmosphere and, it is suitable for isolating the rest of saturated acyclic pentenes, it is necessary according to the Prior art submit the C5 fraction to the distillation treatment. This is highly complex in terms of processing if acyclic and cyclic C5 olefins, in particular cyclopentene, are simultaneously present. Therefore, there is a requirement for a process to remove the cyclopentene in addition to by distillation, with or without other monoolefins, of the C5 fraction, as much as possible with simultaneous production of a new valuable product. An industrially important olefin reaction that maintains the number of C = C double bonds is the metathesis. The term metathesis formally determines the exchange of alkylidene groups between two alkenes in the presence of homogeneous or heterogeneous transition metal catalysts. A simple example of a metathesis reaction that is used in the industry between two acyclic olefins is the conversion of propene to ethene and 2-butene. The ring-breaking polymerization of the cyclic olefins, which proceeds by metathesis mechanism, gives rise to the poly (1-alkenylenes), which are called polyalkanemers. Contrary to the polymerization of the 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, Tld., New York, 1982, vol. 8, pp. 499-551 and in Science (1989) 243, pp 907-915 / and in D.S. Breslow in Prog. Polym. Sci. Vol. 18 (1993) pp. 1141-1195; by H. Hócker and H. Keul in Adv. Mater. 6 (1994) No. 1, pp. 21-36 and in 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 polymerization by metathesis with ring breaking according to the following scheme: In this scheme, in the initiation step (1), a cyclolefin is first added to a metal carbene complex, with the formation of an intermediate, etalacyclobutane, which can be broken down to re-form initial materials or can be opened to give a new complex Carbene with chain elongation. The growth of the chain (propagation) (2) proceeds in the ideal case of the metathesis polymerization with latent ring breaking in such a way that a polymer strand is formed by metallic center, so that monodisperse polymers are obtained having a polydispersity of almost 1. The termination of the chain (3), that is, the separation of the polymer from the metal is generally done by adding an acyclic olefin. In this case, in the ideal case it is possible to exert a directed influence on the length of the chain and regenerate the catalyst. In the case of chain termination using a functionalized olefin, the functionality is transferred to the end of the polymer chain. In BE-A-759774 there is described a process for controlling the molar mass and the distribution of the molar mass in the ring-break metathesis polymerization, in which, for example when preparing a polyoctenamer, 1-pentene is used as the olefin acyclic and thus as a chain termination reagent. By using acyclic olefins, first, the length of the chain can be specifically controlled in the ring-break metathesis polymerization. Secondly, the ethenoisis of the cyclic olefins, in which equimolar amounts of a cyclic olefin are reacted with ethene according to the following scheme: it serves in the preparation of α, β-unsaturated olefins that are otherwise difficult to synthesize. US-A-3, 715, 410 discloses cyclic refining reactants with acyclic olefins for acyclic diophenylene in the presence of what is known as an olefin disproportionation catalyst. In this way, by reacting the cyclic monoolefins or polyolefins not conjugated with ethene, it is possible to prepare acyclic, α-unsaturated or polyene diolefins. The α, β-unsaturated diolefins can be easily converted to diols with terminal hydroxyls, and are used in the preparation of polyesters, for example. Reacting the cyclic monoolefins with a substituted acyclic olefin yields unconjugated acyclic diolefins having a terminal double bond and a substituted terminal double bond, for example when cyclooctene is reacted with propene to obtain 1, 9-undecadiene. These are used, for example as monomers in the homopolymerization or copolymerization to obtain polymers that can be easily crosslinked. DE-A-2 047 270 describes a process for preparing a catalyst for the disproportionation of olefins based in organometallic compounds containing 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 for homo- and cross disproportions, in which a A mixture of two different olefins is reacted with formation of a product mixture according to the following general scheme: RlR2C - CR3R4 + R5R6 = CR7R8 J ==: RlR2C - = CR7 3 + 1 2C = CR5R6 + R3 4C = CR7R8 + R3R4C - CRSRS The disproportionation reactions described include: 1. The conversion of a mixture of an acyclic mono- or polyolefin and a cyclic mono- or polyolefin into an acyclic polyolefin of higher molecular weight. 2. The conversion of one or more cyclic mono- or polyolefins with formation of cyclic polyolefins of molecular weight. 3. The conversion of one or more acyclic polyolefins with formation of cyclic mono- or polyolefins and acyclic mono- or polyolefins. DE-A-2 028 935 discloses polyalkanemers which are prepared by ring-breaking metathesis polymerization from cyclic olefins and unsaturated esters having double bonds that are not located in a ring, a catalyst system consisting of a tungsten compound or molybdenum compound and an organoaluminum compound, as well as a compound containing one or more hydroxyls and / or sulfhydryls is used. DE-A-2 051 798 also describes a process for preparing polyalkanemers by ring-break 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 polyalkanemers by ring-breaking 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 polyalkanemers containing a high cis content of the double bonds present in the polymer, prepared by metathesis polymerization with cis-ring cleavage, cis-cycloocta-1, 5-diene or norbornene, carrying out the polymerization in the presence of open chain 1,3-diene, such as isoprene, or a 1,3-cyclic diene as may be be cyclohexa-1,3-diene. DE-A-2 201 161 describes a process for preparing polymers from cycloolefins, preferably cyclopentene and cyclooctene, by ring-breaking metathesis polymerization using a catalyst system consisting of a transition metal salt, preferably a ( oxy) chrome aluro, molybdenum or tungsten, an organometallic compound of an element of the main group 4, preferably an alkyl or aryl compound of tin or lead, and an aluminum halide. DE-A-2 343 093 describes a process for the polymerization with ring breaking of cyclic olefins on catalysts consisting of: a) a metal halide of groups Vb or VIb of the Periodic Table of the Elements, b) a organometallic compound of a metal of the groups • lia, Illa and IVa of the Periodic Table of the Elements, c) with or without a catalyst containing a double bond C = C conjugated with a double bond C = 0, for example, a aliphatic, ß-unsaturated monocarboxylic or polycarboxylic acid. This process produces polyalkanemers having relatively high polydispersity values in this manner a broad molecular weight distribution.

DE-A-2 424 298 describes a process for preparing segment polymers by ring-breaking metathesis polymerization of a cycloolefin with a high molecular weight oligoolefin, preferably an α, β-diolefin having double bonds in the side chain additional. This produces polymers that have properties designed for the product. Of the aforementioned metathesis processes, the synthesis of olefins, diolefins and especially functionalized olefins to which traditionally is not easily accessible have found wide industrial application. J. Mol. Catal. (1982) 15, pp 21 ff. Describes the olefin metathesis processes developed and used in the industry by Phillips Petroleum Company. Here a distinction is made between processes for preparing monoolefins, which include, for example, the process of triolefins for preparing high purity ethylene and linear butenes from propene and the neohexene process for splitting diisobutylene with ethylene to prepare neohexene (3 , 3-dimethyl-1-butene) and isobutylene, and the processes for preparing α-, β-unsaturated di- and polyenes by the cyclic olefin cytolysis described above. To prepare functionally substituted olefins, special metathesis catalysts are required which are not poisoned by polar substituents. These are based on complexes of Carbene substituted with heteroatoms, such as those initially prepared by E.O. Fischer, which are activated by (oxy) metal halides. A highly active co-catalyst composition is obtained by combining tin (IV) chloride with silicon tetrachloride or germanium tetrachloride, for example. R.L. Banks in J. Mol. Catal. (1980) 8, pp. 269 ff., In the same way describes industrial aspects of the reactions of disproportionation of olefins. US-A-3, 652, 703 describes a process for the metaphysiology of effins using a ruthenium-based catalyst on a silicon dioxide support. US-A-3, 659, 008 discloses a process for preparing non-conjugated acyclic polyenes having 4 carbons between the double bonds, consisting of the disproportionation of ethylene and cyclic polyene containing four carbons between the double bonds, such as 1 , 5-cyclooctadiene, obtaining a mixture of the desired acyclic polyenes as well as more dense and lighter secondary polyenes. US-A-3, 660, 507 describes a process for the metathesis of olefinic mixtures of acyclic and / or cyclic olefins on a catalyst system consisting of an active catalyst composition and magnesium oxide. US-A-3, 792, 102 in the same manner describes the use of a magnesium oxide layer in a bed catalyst in layers for the disproportionation of the mixtures of acyclic and cyclic olefins to prepare dienes. US-A-3, 865, 751 in the same way describes an active catalyst composition for converting olefins, consists of a mixture of magnesium oxide and a catalyst for the disproportionation of olefins. US-A-3, 836, 480 discloses an active catalyst composition for converting olefins, which consists of a catalyst for disproportionation and magnesium oxide which was treated with carbon monoxide, nitrogen monoxide or hydrogen. US-A-4, 707, 465 describes an improved olefin disproportionation catalyst that separates by mixing an inorganic oxide of high melting point which contains a catalytically active amount of molybdenum oxide or tungsten oxide with an alkali metal dithionite salt. or alkaline earth metal dithionite salt as a promoter. US-A-3, 637, 893 discloses a process for disproportionating two unconjugated olefins on a disproportionation catalyst consisting of a perchlorinated hydrocarbon and a high melting inorganic oxide containing at least 0.1 wt. molybdenum or tungsten oxide.

US-A-3, 691, 095 discloses a process for preparing catalysts for disproportionation reactions of olefins by the reaction of a transition metal carbonyl complex of the formula An (MM '(CO) gLm) "n, where A is an alkali metal cation or an ammonium, phosphonium or arsonium cation, M is a metal of subgroup 6, M 'is a metal of subgroup 7 or 8 L is a monodentate or didentate ligand, such as CO, NH3 , hydrazine, etc., with an ammonium, phosphonium or arsonium halide and an organometallic activator that includes an organoaluminum halide. J. Am. Chem. Soc. 92 (1970) pp. 528 ff. Describes homogeneous catalysts for disproportionation reactions of olefins based on nitrosyl molybdenum and tungsten compounds. The catalysts are produced by reacting nitrosyl molybdenum and nitrosyl tungsten derivatives with organo aluminum compounds, such as C2H5AICI2 and (CH3) 3Al2Cl3 and are suitable for most of the aforementioned olefin metathesis reactions. Another important metathesis reaction is cross-metathesis, which, as already mentioned, is described, for example, in BE-A-759 774. C. R. Acad. Se, Ser. C (1973) pp. 1077 ff. describes the metathesis between cycloocta-1, 5-diene and 4-octene using the catalyst system finally obtaining polybuta-1,4-dienes obtained by cross-metathesis between an acyclic monomer or oligomer and one cyclical in each case. US-A-3, 622, 644 describes a process for preparing oligomers from ethene and a cyclic monoolefin, preferably cyclopentene, using a catalyst consisting of: a) a rhenium complex of the formula (L) 2 ReOX3, where X is halogen and L is a ligand derived from phosphorus, arsenic or trivalent antimony and b) an organoaluminum compound. US-A-4, 654, 461 discloses a process for preparing 1,5,9-tetradecatriene having a high cis content by disproportionation of 1,5-cyclooctadiene and 1-hexene in the presence of a heterogeneous catalyst based on sodium oxide. molybdenum on silicon dioxide support having a high surface area. Only the product of the simplest cross-metathesis, which was obtained in a yield of only 9%, is in the area of interest of the present publication EP-B-0 235 742 describes a process for preparing 9-alkenyl esters, the cross-metathesis product of cyclooctene and an α-olefin having 3 to 12 carbon atoms, with 1, 9-alkadiene being prepared in a first reaction step In this process, the catalyst is selected from the group consisting of silicon dioxide, aluminum oxide, aluminum phosphate, zirconium phosphate, calcium phosphate, magnesium phosphate, titanium phosphate or thorium oxide, which contains a promoter. Makromol Chem. 141 (1970) pp. 161 ff. describes the telomerization of cyclic olefins with acyclic olefins in the presence of WOCI4 / AI (C2H5) 2C1 or WOCl4 / Sn (C4H9) 4 as a catalyst. The term telomerization is applied to a polymerization in which a molecule -AB, which is called the telogen is reacted with n molecules of a monomer M, which is called the taxogen, to give an oligomer or polymer A (M) nB, which is called the telo ero. At the end of the telomeres obtained by metathesis, two identical or different groups are placed which are formed from the acyclic olefin by a non-continuous reaction. The chain termination reaction, with formation of the telomeres, can be considered as a cross-metathesis. The telomere distribution obeys a statistical law and is in accordance with the following reaction scheme, which consists of: a) the disproportionation of the acyclic olefins, b) the polymerization of the cyclic defines, and c) the telomerization of the cyclic olefins with acyclic olefins. The postulated mechanism is studied with different telomerizations, for example, that of cyclopentene and 2-pentene, the distributions of the experimental product being compared with the calculated ones (assuming the previous mechanism). Based on the good agreement obtained, the supposed mechanism seems to be realistic. In the telomerization of cyclopentene and 2-pentene only a relative oligomer content of about 30 mol% or less was obtained with the two catalyst systems used. This excludes the method described for the industrial preparation of mixtures of C5 oligomers. There is no reference for a possible use of the C5 olefin mixtures from petroleum refining fractions as initial material mixtures. J. Lal, R.R. Smith and J.M. O'Connor, in Polym. Prepr.

(Am. Chem. Soc, Div. Polym. Chem.) 13 (1972) 2, pp. 914 ff., Describes a process for preparing polyenes by cross-metathesis of a cyclomono-olefin, such as cyclooctene, or of a cyclodiene not conjugated with an α-olefin, such as 1-hexene on a catalyst at room temperature and with reaction times from about 1 to 2 hours. Analysis by gas chromatography of the cross-metathesis products showed a maximum product in a carbon number of 14. The products resulting from the cross-metathesis to increase the molar mass were then subjected to a copolymerization with the α-olefin previously used. J. Org. Chem. 40 (1975) pp. 775 ff. describes the metathesis of 1-hexene and cyclooctene. You get three different series of homologous products of non-conjugated, linear polyenes, depending on the products of the primary metathesis. Series A are byproducts of 1, 9-decadiene of the formula: CH2 = [= CH (CH2) eCH =] = n CHC4H9 which has a double terminal link and one internal termination. These originate from the cross-metathesis between hexene and cyclooctene. The B series are by-products of 5-decene of the formula: C4H9CH = [= CH (CH2) 6CH =] = n CHC4H9 that have two double internal termination links. These originate from the metathesis of hexane itself, with formation of 5-decene and ethene. The C series are byproducts of 1, 9-tetradecadiene of the formula: with two terminal termination double bonds. These originate from the crossed metathesis between cyclooctene and the ethene formed in the B series. The main product of the reaction was C4H26 (1/9-tetradecadiene) from the cross-metathesis of 1-hexene and cyclooctene, with a total content of 40% by weight. However, other reaction products from the three aforementioned series can be detected with higher molecular weights, where the total conversion of the cycloolefin was greater than 70%. The catalysts used were derivatives of C16 and an organometallic compound, preferably Clg / EtAC ^ / EtOH and WCl6 / Bu4Sn / 2Et20. US-A-3,527,828 discloses a process for preparing hydrocarbon telomeres (polyenes) by reaction of an acyclic monoolefin with a monocyclic or polycyclic olefin, which contains up to 4 condensed rings and up to four unconjugated double bonds, on a heterogeneous catalyst of molybdenum oxide or rhenium oxide. As examples of metathesis, the following pairs of initial materials of cyclic olefins (taxogen) and acyclic olefins (telogen) were subjected to reaction, being obtained by corresponding polyenes (telomeres): a) cyclopentene and ethylene produced as main products 1, 6, 11-dodecatriene (selectivity 18.7%) and 1, 6, 11, 16-heptadecatetraene (selectivity 5.5%) in a cyclopentene conversion of 35.6%; b) Cyclopentene and 1,6-heptadiene produced as main products 1, 6, 11-dodecatriene (selectivity 51%) and 1, 6, 11, 17-octadecatetraene (selectivity 35%) at a 12% cyclopentene conversion; c) cyclooctene and ethylene produced as main products 1, 9-decadiene, 1, 9, 17-octadecatriene and 1, 9, 17, 25-hexacosatetraene, with the conversion rate of cyclooctene between 25 and 71%, as a function of the reaction temperature; d) norbornene and ethylene produced mainly Ci6, C23 and C30 telomeres at a norbornene conversion rate of 62%. In this publication, and in none of the other publications mentioned above, there is a reference to the possible use of olefin mixtures of C5 from the refining of petroleum to prepare oligomers (telomeres) EP-A-691 318 describes a process for preparing a mixture of C4 olefins containing mainly isobutene and 1-butene, as well as propene. In this process, a mixture of C5 hydrocarbons containing olefins, for example, produced in the steam thermofraction of naphtha, is initially subjected to a hydrogenation with subsequent fractionation and then reacted with ethene in a metathesis reaction. The catalysts for the metathesis used in this process are exclusively heterogeneous catalysts of rhenium oxide, tungsten oxide, molybdenum oxide and cobalt oxide. He The objective underlying the publication is to provide a process for preparing isomeric butenes, ie, olefins having a molecular weight lower than those present in the initial hydrocarbon mixture (Cs fraction). To achieve this goal, the metathesis reaction is carried out in the presence of an up to 10 times molar excess of ethene, with the undesirable auto-metathesis of the C5 fraction suppressed in this process. There is no reference in the publication for the possibility of using the autoethesis for the oligomerization of cyclic and acyclic olefins present in the C5 fraction, in the context of a metathesis polymerization with ring breaking. An objective of the present invention is to provide a process for processing a mixture of C5 from petroleum refining (C5 fraction) which, in addition to saturated hydrocarbons, contains cyclic and acyclic monoolefins, where olefins, as much as possible With conversion into a valuable product, they will be separated from the acyclic hydrocarbons. In this case, for convenience the product of value has a molecular weight higher than that of the olefins. We have found that this goal is obtained, surprisingly, by a process for preparing mixtures of oligomers derived from cyclopentene, the C5 fraction being subjected to a metathesis reaction. The oligomers novel preparations according to the invention are suitable, for example, as intermediates for final products obtainable by functionalizing the double bonds in the context of a polymer-like reaction. The present invention thus relates to a process for preparing mixtures of cyclopentene-derived oligomers of the formula I.

RVc = [= CH - (CH2) 3 - CH =] = nCR3R4 (I) where n is an integer from 1 to 15, R, R, R, R independent of each other are hydrogen or alkyl, which comprises the reaction, in a metathesis reaction homogeneously or heterogeneously, a mixture of hydrocarbons containing cyclopentene and acyclic monoolefins and originates from the refining of oil by thermo-fractionation (fraction of C5). The value n in formula I is the number of cyclopentene units introduced into the oligomers derived from cyclopentene by metathesis reaction with ring breaking. Preferably, the process according to the invention produces mixtures of oligomers in which a very large proportion, for example, at least 40% by weight (determined by integration of the gas chromatograms area; instrument: Hewlett Packard; detector: flame ionization detector; column: DB 5.30 mx 0.32 mm, coating 1 μ; temperature program: 60 ° C 5 minutes, isothermal, speed heating temperature 10 ° C / minute maximum: 300 ° C), has a value of n > 1. The value of n and thus the degree of metathesis with ring breaking, can, as explained below, be influenced by the activity of the catalyst for metathesis used. The radicals R 1, R 2, R 3 and R 4 are independent of each other, hydrogen or alkyl, where the term "alkyl" includes straight-chain and branched alkyl groups, Preferably, these are straight or branched chain C 1 -C 15 alkyl, preferably C 1 -C 10 alkyl, particularly preferably C 1 -C 5 alkyl Examples of the alkyl groups are, in particular methyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1- dimethylethyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1-methylpentyl, 2- methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3, 3-dimethylbutyl, 1,1, 2-trimethylbutyl, 1,2,2-trimethylpropyl, 1-ethylbutyl, 2-ethylbutyl, l-ethyl-2-methylpropyl, n-heptyl, 1-methylhexyl, 1-ethylpentyl, 2-ethylpentyl, 1-propylbutyl, octyl, decyl, dodecyl, etc. The degree of branching and the number of carbons of the alkyl terminating radicals R 1, R 2, R 3 and R 4 depends on the structure of the acyclic monoolefins of the hydrocarbon mixture used and the activity of the catalyst.

As described below with greater precision, the activity of the catalyst influences the degree of cross-metathesis (self-synthesis) of the acyclic olefins with formation of structurally novel olefins in which the cyclopentene is then formally inserted in the context of the polymerization by metathesis with ring breaking. Preferably, by means of the process according to the invention, mixtures of oligomers having a high proportion of oligomers with a single terminal double bond are prepared. The metathesis reaction formally includes: a) the disproportionation of the acyclic monoolefins of the mixture of hydrocarbons by cross-metathesis, b) the oligomerization of the cyclopentene by metathesis with ring breaking, c) chain termination by reaction of the oligoes of b) with an acyclic olefin of the mixture of hydrocarbons or a product of a), where steps a) and / or b) and / or c) may proceed repeatedly, alone or in combination.

Step a) Cross-metathesis of acyclic monoolefins should be described with the metathesis example of 1-pentene and 2-pentene: CH2-CH C3H7 +:? == propene + 1-butene + 2-hexene CH3 CH-CH C2H5 + 3_heptene For the combinations of the crossed metathesis of different acyclic olefins and the self-synthesis of identical acyclic olefins, such as the self-synthesis of 1-pentene to obtain ethene and 4-octene, and by the repeated step through this reaction a multiplicity is obtained of monoolefins having different carbon structures and numbers which form the end groups of the oligomers according to the invention. The product content of the cross-metathesis that increases with the increasing activity of the catalyst used also influences the content of the double bonds of the oligomers. Thus, in the case of the self-synthesis of 1-pentene described above, ethene is released, which can escape, if appropriate, in gaseous form, with one equivalent of one double being eliminated from the reaction. link. At this time the content of oligomers without terminal double bonds increases. Thus, in the previous example, an oligomer without terminal double bonds is formed, for example by the insertion of cyclopentene into 4-octene.

Step b) The average number of insertions of cyclopentene in the growing chain in the context of a ring-break metathesis polymerization determines the average molecular weight of the cyclopentene oligomer mixture formed. Preferably, the process according to the invention forms mixtures of oligomers having an average molecular weight of at least 274 g per mole, which corresponds to an average number of 3 units of cyclopentene per oligomer.

Step c) The termination of the chain is carried out by reacting an oligomer, which still has an active chain end in the form of a catalyst complex (alkylidene complex), with an acyclic olefin, being recovered, in the ideal case, an active catalyst complex. The acyclic olefin can originate without changing the hydrocarbon mixture originally used for the reaction or may have been previously modified in a cross-metathesis according to step a). The process according to the invention is generally very suitable for preparing oligomers from mixtures of hydrocarbons containing acyclic and cyclic olefins. Preferably, a mixture of hydrocarbons that is raised on an industrial scale is used in the refining of the petroleum which, if desired, can be subjected in advance to a catalytic partial hydrogenation to remove dienes. A mixture that is particularly suitable for use in the present process is, for example, a mixture enriched in saturated and unsaturated C5 hydrocarbons (C5 fraction). To obtain the C5 fraction, the gasoline from the pyrolysis produced in the steam thermofraction of naphtha can, for example, first be subjected to a selective hydrogenation to selectively convert the dienes and acetylenes present in the corresponding alkanes and alkenes and can then be subjected to fractional distillation, with, on the one hand, the fraction of C6-8 that is of importance for other chemical syntheses and contains the aromatic hydrocarbons that are being produced, and on the other hand the fraction of C5 used for the process of agreement with the invention that is going to be produced.

The C5 fraction generally has a total olefin content of at least 30% by weight, preferably at least 40% by weight, in particular at least 50% by weight. Suitable C5 hydrocarbon mixtures are those having a total cyclopentene content of at least 5% by weight, preferably at least 10% by weight, in particular at least 12% by weight and, in general, no more than 30% by weight. % by weight, preferably not more than 20% by weight. In addition, mixtures of suitable C5 hydrocarbons have a content of pentene isomers in the acyclic monoolefins of at least 70% by weight, preferably at least 80% by weight, in particular at least 90% by weight. a preferred embodiment according to the process of the invention is a C5 fraction that is produced on an industrial scale which has a total olefin content of, for example, from 50 to 60% by weight, such as approximately 56%, a cyclopentene content of, for example, from 10 to 20% by weight, such as approximately 15% by weight, and an isomer content of pentene, for example from 33 to 43% by weight, such as approximately 38% by weight, approximately 16% by weight due to n-pentene and approximately 22% by weight 'to isomeric pentenes.

According to a specific embodiment of the process according to the invention, a hydrocarbon mixture comprising the C5 fraction and a petroleum fraction containing acyclic olefins of C4 (refined 2) is used. According to another specific embodiment of the process according to the invention, a mixture of hydrocarbons is used which contains the C5 and ethene fraction. In this case, oligomer mixtures with a high content of double bonds are obtained. On the one hand, this is achieved by ethenolysis of the acyclic n- and isopentenes present in the C5 fraction to obtain shorter chain α-olefins, such as propene and 1-butene, which reacts with cyclopentene in a metathesis reaction with ring breaking with formation of oligomers each of which has a terminal double bond. In the presence of ethene, the self-synthesis of acyclic olefins with the formation of more ethene is suppressed, such as the self-synthesis of 1-pentene to form ethene and 4-octene, which gives rise, as a terminator reagent of the chain, to the products without double terminal links. On the other hand, a greater increase in the content of double bonds is obtained due to the ethenoisis of cyclopentene with ethene to obtain 1,6-heptadiene. This forms a series of oligomers each of which has two terminal double bonds. Preferably, the oligomeric mixtures having a density of Increased functionality result from the use of oligomeric mixtures having increased double bond content for the functionalization thus obtained. Suitable catalysts for metathesis are known from the prior art and include homogeneous and heterogeneous catalyst systems. The catalyst systems described above as a prior art are expressly incorporated by reference. In general, catalysts suitable for the process according to the invention are based on a transition metal of subgroup 6, 7 or 8 of the Periodic Table of the Elements, catalysts based on Mo, W, Re, are preferably used. and Ru.

Suitable homogeneous catalyst systems are, in general, transition metal compounds which, in combination or not with a co-catalyst and / or in the presence or absence of olefinic starting materials, are capable of forming a catalytically active metal carbene complex. Systems of this type are described, for example, in R.H. Grubbs in Comprehensive Organomet. Chem., Pergamon Press, Ltd., New York, vol. 8, (1982) pp. 499 ff. Suitable catalyst / co-catalyst systems based on W, Mo, and Re can, for example, contain at least one soluble transition metal compound and an alkylating agent. These include, for example, M? Cl2 (NO) 2 (PR3) 2/12 (CH3) 3 Cl3; WCl6 / BuLi; WCl 6 / EtAlCl 2 (Sn (CH 3) 4) / EtOH; W0Cl4 / Sn (CH3); W0C12 (O- [2, 6-Br2-C6H3]) / Sn (CH3) 4; CH3Re03 / C2H5AlCl2, with the last four systems mentioned for the process according to the invention being preferred. Other transition metal-alkylidene complexes suitable as catalysts for metathesis are described in R.R. Schrock in Acc. Chem. Res., 23 (1990) pp. 158 ff. In general, these are Mo- and W-alkylidene tetracoordinated complexes which also have two apparent alkoxy ligands and an imido ligand. Preferably ((CH3) 3CO) 2M0 (= N- [2, 6- (i-C3H7) 2-C6H3]) (= CHC (CH3) 2C6H5) and [(CF3) 2C (CH3) 0] 2Mo (= N- [2,5- (i-C3H7) -C6H3]) (= CH (CH3) 2C6H5) are used for the process according to the invention. Particularly preferably, the catalysts for homogeneous metathesis used are the catalysts described in Angew. Chem, 107 (1995) pp. 2179 ff., In J. Am. Chem. Soc. 118 (1996) pp. 100 ff. and in J. Chem. Soc, Chem. Commun., (1995) pp. 1127 ff. These include, in particular RuCl2 (= CHR)) PR'3) 2, preferably (? 6-p-cymene) RuCl2 (P (C6Hu) 3) / (CH3) 3SiCHN2 and (? -p-cymene) RuCl2 (P (C6Hn) 3) / C6H5CHN2. These last two are produced in situ from a molar equivalent of (? -p-cymene) RUCI2 (P (CdHii) 3) and 3 molar equivalent of diazoalkane ((CH3) 3SiCHN3 or C6H5CHN2).

Suitable heterogeneous catalyst systems generally contain a transition metal compound on an inert support which is capable, without co-catalyst, of forming a catalytically active alkylidene complex by reaction with the olefinic starting materials. In the process according to the invention, Re 07 and CH 3 Re 03 are preferably used. Suitable inorganic supports are the oxides customary for this, in particular oxides of silicon and aluminum oxides, aluminosilicates, zeolites, carbides, nitrides, etc. and mixtures of these. Preferably, the supports used are AI2O3, SiO2 and their mixtures, in combination or not with B2O3 and Fe2? 3. The aforementioned homogeneous and heterogeneous catalyst systems differ greatly in their catalytic activity, so that the individual catalysts have different optimal reaction conditions for the metathesis. As already described above, the catalytic activity with respect to cross metathesis (step a)) also influences the product distribution of the oligomeric mixture of formula I derived from cyclopentene. In this way, the homogeneous ruthenium-based catalyst systems RUCI2 (= CHC6Hs) (P (CßHn) 3) 21 (? Dp-cymene) RuCl2 (P (C6Hu) 3) / (CH3) 3SiCHN2 and (? 6-p) -cimene) RUCI2 (P (CdHn) 3) / C6H5CHN2 are particularly suitable for the process according to the invention. The aforementioned ruthenium complex has a higher catalytic activity then [sic] the latter two mentioned, which, with the otherwise identical reaction conditions, give rise to higher space-time yields. However, at the same time, with the first complex of crossed metathesis it occurs to an increased degree, being also some ethene released and in this way the mixture of oligomers derived from cyclopentene obtained has a slightly lower double bonds content, which it is expressed as a lower iodine index, for example. In addition, due to cross-metathesis, the higher number of acyclic olefins without terminating double bonds are available, so that, using the homogeneous ruthenium catalyst mentioned above, the cyclopentene-derived oligomers of the formula I having only one double terminal bond or none, are obtained in an increased amount. The two ruthenium complexes mentioned last have a somewhat lower catalytic activity than the one mentioned at the beginning, so that by using them in the process according to the invention the mixtures of cyclopentene-derived oligomers of the formula I are obtained with a content of double bonds greater and in this way a higher iodine index as well as a larger number of double bonds terminals. The heterogeneous catalyst systems also have the differences described above in activity together with the corresponding effects on the products of the metathesis. If CH3Re? 3 is used over AI2O3 as a heterogeneous catalyst for the process according to the invention, this catalyst has a higher catalytic activity than the corresponding homogeneous catalyst system of CH3Re03 / (C2H5) A1C12. For convenience, the heterogeneous catalyst used is Re207 over AI2O3. This has an activity 'approximately comparable with RuCl2 (= CHC6Hs) (P (CßHn) 3), as well as a similar product distribution and can be reused, after regeneration in an air stream at elevated temperatures, such as approximately 550 ° C. If desired, depending on the catalyst used, oligomeric mixtures derived from cyclopentene having a variable double bond content and variable contents of terminal double bonds can thus be obtained. According to a particularly preferred embodiment of the process according to the invention, the metathesis catalyst used is a homogeneous, ruthenium-based catalyst selected from the group consisting of RuCl2 (= CHC6H5) (P (C6Hu) 3) 2CH3) 2, (? 6-p-cymene) RuCl2 (P (C6HU) 3) / (CH3) 3SiCHN2 and (? Dp-cymene) RuCl2 (P (C6Hn) 3) / C6H5CHN2, which is added to the reaction mixture as a solution in an organic solvent. Suitable solvents are, for example, aromatic hydrocarbons, such as toluene and xylene, as well as halogenated alkanes such as CH 2 Cl 2 CHCl 3, and the like. The reaction temperature in the case of the reactive catalyst systems is from -20 to 200 ° C, preferably from 0 to 100 ° C, in particular from 20 to 80 ° C. The reaction can be carried out at a high pressure of up to 5 bar, preferably up to 2 bar or, particularly preferably at ambient pressure. According to another particularly preferred embodiment of the process according to the invention, the catalyst for metathesis used is a heterogeneous catalyst based on rhenium selected from CH3Re? 3 / l2? 3 and preferably Re2? 7 / Al2? 3, the which is added the reaction mixture without addition of solvent. The reaction temperature when these catalysts, which are somewhat less active compared to the aforementioned homogeneous catalyst systems, are used is from about 20 to 120 ° C, preferably from 30 to 100 ° C, in particular from 40 to 80 ° C. ° C.

The preferred reaction is carried out at a high pressure from 2 to 20 bar, preferably from 3 to 15 bar, in particular from 4 to 12 bar. The equipment for the process according to the invention can be designed for continuous processes or in batches. Reaction apparatuses are known to those skilled in the art and are described, for example, in Ullmanns Enzylopadie der technischen Chemie [Ullmanns Encyclopedia of Industrial Chemistry], vol. 1 (1951) pp. 743 ff. These include, for example, the process in batches, tanks with agitation, for example, and for the continuous process tubular reactors for example. According to a suitable batch variant of the process according to the invention, the C5 fraction, for example, can be reacted on one of the homogeneous ruthenium catalysts which have been described above as preferred and which are generated if desired in in situ in the reaction vessel to obtain mixtures of cyclopentene-derived oligomers of the formula I in a metathesis reaction. According to another suitable continuous variant of the process according to the invention, the C5 fraction, for example, can be subjected to reaction in a tubular reactor on one of the heterogeneous rhenium catalysts, previously described as preferred.

The space-time yields of at least 10 g 1 h-1, more preferably at least 15 1 l-1 h_1, are obtained with both possible process variants, depending on the catalyst used and the remaining reaction parameters, especially the temperature of reaction. However, depending on the activity of the catalyst it is also possible to obtain significantly higher space-time yields up to approximately 500 g 1 -i h-i. The reaction mixture is fractionated by the usual processes. These include, for example, fractional distillation, which may be carried out under reduced pressure, or separation at elevated temperatures and atmospheric pressure in a falling film evaporator. Low-boiling fractions still containing unreacted olefins can, if desired, be recycled to the reaction apparatus. As an advantage in the process according to the invention, a substantial conversion of the olefins present in the C5 fraction to oligomers is obtained, so that the low-boiling separate substances consist of a mixture of C5 hydrocarbons which mainly contain cyclic and acyclic saturated compounds. These can be fed for industrial use, if appropriate after another fractionation by distillation in mixtures of cyclopentane and n- / isopentane. Cyclopentane, for example, is used as a substitute for CFCs and HCFCs, which are of interest with respect to the damage to the atmosphere, as blowing agents for polyurethane systems, to produce hard foams. The mixtures of n- / isopentane, for example, serve as solvents for foaming polymers and as propellants for aerosols. The invention furthermore relates to mixtures of cyclopentene-derived oligomers of the formula I obtained by the process according to the invention. As described above, the number and position of the double bonds in the oligomers can be included by the reaction conditions, in particular the catalyst used in each case. The process according to the invention produces oligomers of cyclopentene, the iodine value being at least 250 g of I2 / 100 g of the oligomer, preferably at least 300 g of I2 / 100 g of oligomer. The average molecular weight of the oligomers derived from cyclopentene is at least 274 g / mol, which corresponds to an average reaction of 3 units of cyclopentene per oligomer, assuming in this case the termination of the chain due to an acyclic pentene (and not due to a cross-metathesis product). Particularly preferably, the mixtures of oligomers of the formula I serve as intermediates for another process by functionalization of at least some of the double bonds present therein. This can carried out in the context of a reaction similar to polymers, such as catalytic hydroformylation. The oxo products thus obtained have a multiplicity of possible uses, for example as additives in sealant compositions, compatibilizers, adhesives, scale inhibitors, polyelectrolytes, complexing agents, tanning additives, and so on. The following non-restrictive examples illustrate the invention Examples The gas chromatograms were recorded using a Hewlett Packard 5890 gas chromatograph equipped with 5.30 m x 0.32 DB glass capillary column and a flame ionization detector with attached integration unit.

Example 1: (model system) A 1: 1 mixture of 17.1 mole each of cyclopentene and 1-pentene was mixed at room temperature and atmospheric pressure with a catalyst mixture generated in situ of 8.6 mmol of (p-cymene) RuCl2 (PCV3) and 2 ml of Me3SiCHN2 in 50 ml of CH2Cl2. In this case a slight gas evolution was observed. After stirring for 3 hours, The solution was subjected to chromatography on neutral AI2O3, and the colorless filtrate was released by distillation of the low-boiling substances that did not react. 956 g of the low viscosity, colorless liquid of the following composition (percent of CG area remained): 26% Cío-Hiß, 22% C? 5H26, 17% C20H34, 13% C25H42, 10% C30H50, 7% C35H58 , 5% C4oH66 'iodine value: 351 g I / 100 g.

Example 2: (metathesis of the homogeneously catalyzed fraction of C5) 1 1 of the C5 fraction (cyclopentene content: 15%) was reacted at room temperature and atmospheric pressure with a 0.6 m-mol solution of RuCl2 (= CHPh) (PCY3) 2 in 20 ml of CH2C12. In this case a slight gas evolution was observed. After stirring for 1 hour, the solution was subjected to chromatography on Al2 3 3, and the colorless filtrate was released by distillation of the low-boiling substances which did not react. 96 g of a low viscosity, colorless liquid of the following composition (percent of CG area) were obtained: 4% C7H12, 11% C8H6, 14% CioHis, 3% C12H28, 8% C3H24, 12% C? 5H26, 2% C17H28, 5% C18H32, 9% C20H34 / 1% C22H36, 4% C23H40, 7% C25H42, 3% C28H48, 6% C30H50, 1% C33H56, 4% C35H58 3% C40H58, 3% C40H66, 2% C40H66, 1% C4oH66 - iodine index: 329 g of I2 / 100 g Example 3: (model system) A 1: 1 mixture of cyclopentene and 1-pentene was pumped continuously into a tubular reactor loaded with Re2? 7 / Al2? 3 at 60 ° C, 5 bar and during residence times of 1-3 hours. The product of the reaction was then separated into a fraction of low-boiling and high-boiling substances using a falling film evaporator operated at 115 ° C and atmospheric pressure, and the fraction of low-boiling substances was recycled for the metathesis process. The fraction of high-boiling substances was released at reduced pressure from the residual amounts of low-boiling substances. With space-time yields of 50-500 g 1 ~ h ~, slightly yellowish liquids were obtained, which were then subjected to chromatography on AI2O3. A sample taken had the following composition (percent of CG area): 3% C7Hi2, 9% C8H6, 16% CioHiß 2% C2H2o 8% C3H24, 13% C5H26, 2% C17H28, 6 % C18H32, 11% C20H34, 1% C22H36, 4% C23H40 / 9 C25H42, 2% C28H48, 6% C30H50, 3% C35H58, 2% C40H66 1% C40H66 1% C45H74.

Iodine number: 349 g of I2 / 100 g Example 4: (metathesis of the fraction of C5 catalyzed heterogeneously) 1 1 of the C5 fraction was pumped continuously to a tubular reactor loaded with Re2? 7 / Al2? 3 at 60 ° C, 5 bar and during residence times of 1-3 hours. The product of the reaction was separated into a low boiling fraction and a high boiling fraction using a falling film evaporator operated at 115 ° C and atmospheric pressure. The fraction of high-boiling substances was released from the residual amounts of low-boiling substances by distillation under reduced pressure. With space-time yields of 20-100 g 1 -i h-i and cyclopentene conversion rates up to 70%, slightly yellowish liquids were obtained which were then subjected to chromatography on Al2? 3. One sample had the following composition (percent of CG area): 4% C7H2, 11% C8H6, 14% C0H18, 3% C2H20, 8% C13H24, 12% C5H26, 2 % C17H28, 5% C? 8H32, 9% C20H34, 1% C22H36, 4% C23H40, 7% C25H42, 3% C28H48, 6% C30H50, 1% C33H56, 4% C35H58, 3% C40H66. 2% C45H74 1% C50H82-iodine value: 325 g of I2 / 100 g Example 5: 1 1 of the fraction of Cs, in an equimolar ratio with the refined II, was pumped continuously to a tubular reactor loaded with Re2? 7 / Al2? 3 at 60 ° C, 11 bar and during times of stay of 1-2 hours . The product of the reaction was separated into a fraction of low-boiling substances and a high-boiling fraction of substances using a falling film evaporator operated at 100 ° C and atmospheric pressure. The fraction of high-boiling substances was released from the residual amounts of the low-boiling substances by distillation under reduced pressure. With space-time yields of 50-200 g 1 -i h-i, and cyclopentene conversion rates around 80%, slightly yellowish liquids were obtained, which were then subjected to chromatography on AI2O3. The samples were then analyzed by GC and contained the following families of products that could no longer be unambiguously assigned: C6H12, C7H12, CsH? 4, C9H16, + individual byproducts up to C49H80-iodine number: 356 g of I2 / IOO g Example 6: (Continuous etheolysis of cyclopentene) The cyclopentene, under 30 bar of ethene, was pumped continuously into a tubular reactor loaded with Re2? 7 / Al2? 3 at 60 ° C and during residence times of 1-2 h. The product of the reaction was separated into a fraction of low-boiling substances and a high-boiling-substance fraction using a film evaporator-descent operated at 80 ° C and atmospheric pressure. The fraction of high-boiling substances was released from the residual amounts of low-boiling substances by distillation under low vacuum. With space-time yields of 100-350 g 1 -1 h-1 and cyclopentene conversion rates of around 85%, orange-yellow liquids were obtained which had the following composition after chromatography on AI2O3 (percent of the CG area:) 29% C7H? 2, 4% C8Hi4, 24% C? 2H20, 3% C? 3H22r 17% C? 7H28, 1% C? 8H30, 12% C22H36, 1% C23H38, 8% C27H44, 1% higher olefins iodine number: 384 g of I2 / 100 g Example 7: (heterogeneously catalyzed batch etheolysis of the C5 fraction) 60 ml of the C5 fraction were treated with ethene at 30 bar, at room temperature in a 100 ml pressure vessel which was charged with 10 g of Re2? 7 / Al2? 3. After heating to 60 ° C, the ethene was introduced at a total pressure of 70 bar and this pressure was kept constant during the course of the reaction. After 2 hours the reaction mixture was cooled to room temperature and carefully depressurized. The colorless solution thus obtained, after removing the low-boiling substances by distillation, had the following composition (percent of the CG area): 16% C7H12, 12% C8Hi4, 6% C9H? 6, 2% C? 0H? 8, 14% C? 2H20, 9% C? 3H22, 3% C? 4H24, 1% C15H26, 9% C? 7H28, 6% C? 8H30, 2% C19H32, 6% C22H36, 2% G23H38, 4% C27H44, 8% higher olefins Yield: 11 g of iodine index oligomers: 376 g of I2 / 100 g Example 8: (batch etheolysis of the homogeneously catalyzed C5 fraction) In a 100 ml pressure vessel, 60 ml of the C5 fraction were mixed at room temperature with a solution of 84 mg (0.10 mmol) of RuCl2 (= CHPh) (PCy3) 2 in 2 ml of CH2Cl2 and immediately pressurized to 70 bar with ethene. The pressure was kept constant during the course of the reaction by regularly introducing ethene. After stirring for 1 hour at room temperature, the reaction mixture was carefully depressurized. The colorless solution thus obtained, after separating the low-boiling substances by distillation, had the following composition (per cent of the CG area): 13% C7H12, 12% C8Hi4, 6% C9H16, 1% C10H? 8, 10% C? 2H20, 11% C13H22, 4% C? 4H24, 9% C? 7H28, 8% C? 8H30, 3% C? 9H32, 4% C23H38, 3% C27H44, 10% higher olefins Yield: 12 g of iodine index oligomers: 372 g of I2 / 100 g

Claims (16)

1. CLAIMS A process for preparing mixtures of oligomers of the formula I.
2. R1R2C = [= CH - (CH2) 3 - CH =] = CR3R4 (I), which are derived from cyclopentene, where n is an integer from 1 to 15, R 1, R 2, R 3, R 4 independent of each other are hydrogen or alkyl, which consists of the reaction, in a metathesis reaction catalyzed homogeneously or heterogeneous, of a mixture of hydrocarbons containing cyclopentene and acyclic monoolefins, originated from the refining of oil by thermo-fractionation (fraction of Cs) and shows a content of cyclopentene of at least 5% by weight and a content of pentene isomer of the monoolefins acyclics of at least 70% by weight.
3. The process as mentioned in claim 1, wherein the metathesis reaction consists of: a) the disproportionation of the acyclic monoolefins of the mixture of hydrocarbons by cross-metathesis, b) oligomerization of the cyclopentene by ring-breaking metathesis, c) termination of the chain with the reaction of the oligomers of b) with an acyclic olefin of the hydrocarbon mixture or of a product of a), where steps a) and / or) and / or c) can proceed repeatedly, alone or in combination.
4. The process as mentioned in one of claims 1 or 2, wherein a mixture of hydrocarbons having a total olefin content of at least 30% by weight is used.
5. The process as recited in claim 3, wherein a mixture of hydrocarbons having a cyclopentene content of at least 10% by weight is used.
6. The process as recited in any of claims 3 or 4, wherein a mixture of hydrocarbons is used in which the pentene isomer content of the acyclic monoolefins is at least 80% by weight, The process as mentioned in either of claims 1 or 2, wherein a mixture of hydrocarbons containing the C5 fraction and a petroleum fraction containing acyclic olefins of C4 (refined 2) is used.
7. 7. The process as mentioned in any of claims 1 or 2, wherein a mixture of hydrocarbons containing the C5 and ethene fraction is used.
8. 8. The process as recited in any of claims 1 to 7, wherein a catalyst containing at least one transition metal of subgroups 6, 7, or 8 is used.
9. 9. The process as recited in claim 8, wherein a catalyst is used which contains: a) at least one complex of the transition metal-alkylidene (transition metal-carbon complex) or b) a combination, suitable for forming a complex a), of a transition metal compound and at least one other agent, preferably an alkylating agent, or c) a suitable transition metal compound to form a complex a) with the olefins present in the hydrocarbon mixture.
10. The process as recited in any of claims 8 or 9, wherein a homogeneous catalyst is used which is selected from the group consisting of ruthenium-alkylidene complexes of the formula RUCI2 (= CHR) PR '3), complexes molybdenum-alkylidene, and CH3Re? 3 / C2H5AlCl2, OCl2 (O- [2, 6-Br2- C6H3]) / Sn (CH3) 4, WC16 / C2H5A1C12 (Sn (CH3) 4) / EtOH, WOCl4 / Sn (CH3) 4.
11. The process as recited in any of claims 8 or 9, wherein uses a heterogeneous catalyst that is selected from the group consisting of Re207 and CH3Re? 3 in an inorganic support.
12. 12. The process as mentioned in claim 7, wherein the reaction is carried out at a pressure from 1 to 200 bar.
13. 13. The process as recited in claim 7, wherein the reaction is carried out at a pressure of from 20 to 150 bar.
14. The process as mentioned in claim 7, wherein the reaction is carried out at a pressure of from 40 to 100 bar.
15. 15. Mixtures of cyclopentene oligomers of the formula I, which can be obtained by a process as mentioned in one of claims 1 to 14.
16. 16. The use of the cyclopentene oligomer mixtures as mentioned in claim 15 as intermediaries for other processing by functionalization of at least some of the double bonds present.