P OR AS DERIVATIVE OF A CYCLOPENTADIENE

Abstract: The invention relates to a process for the preparation of a P or As derivative of an at least bi-substituted cyclopentadiene. The invention is characterised in than an at least mono-substituted spiro-[2,4]-hepta-4,6-diene is reacted with an alkali metal phosphine or an alkali metal arsine. The invention also relates to a number of P or As derivatives of cyclopentadiene.

Description: P OR AS DERIVATIVE OF A CYCLOPENTADIENE The invention relates to a process for the preparation of a P or As derivative of an at least di- substituted cyclopentadiene. Such a process is known from the article of J. Szymoniak et al . in J. Org. Chem., . 55 . , 1429-32 (1990), which describes the conversion of a tetramethylcyclopentadienyl anion into the P derivative with the aid of a phosphorus compound. Such a process results in a high degree of geminal substitution of the cyclopentadiene. (See for instance P. Jutzi's article in Synthesis, July 1993. pp. 684-6). The drawback of such geminally substituted cyclopentadienes is that they cannot be converted into a cyclopentadienyl compound and therefore they cannot be applied as ligands in an organometal complex. A process has now been found in which a higher selectivity towards the non-geminally substituted P or As derivative of cyclopentadiene is obtained. The process is characterized in that an at least mono-substituted spiro-[2 , 4]-hepta-4, 6-diene is reacted with an alkali metal phosphine or arsine. The process starts from the conversion of a spiro-[2,4]-hepta-4, 6-diene (SHD) with the aid of a phosphorus (P) or arsenic (As) compound. The SHD to be used has the following formula: in which at least one of the carbon atoms, numbered 4- 7, is substituted with a substituent S, which can be a hydrocarbon group or an element or a group comprising an element chosen from groups 13-17 of the Periodic System of the Elements. The number of substituents n thus satisfies the relation: 1 < n < 4 . The number of substituents m satisfies the relation: 0 < . m < . 4. The hydrocarbon group with which compound (I) is been substituted on the carbons numbered 4-7 can be chosen from the group comprising alkyl, aryl or aralkyl. If several of said carbon atoms are substituted, such substituents may also form part of a ring system, such as may occur for instance in cyclopentadiene derivatives derived from indene, tetrahydroindene, fluorene and similar compounds. Examples of substituents on the carbons numbered 4-7 are methyl, ethyl, propyl, isopropyl, n-butyl, i-butyl, t-butyl, phenyl, benzyl, cyclohexyl, trimethylsilyl. The carbon atoms numbered 1-2 shown in formula (I) may also be substituted. Such a substitution can be of the same nature as the above- described substitution on the cyclopentadienyl ring. From an article by Kaufman (in Angew. Chem. 92 (4) , 321-3, 1980) it is known to react an unsubstituted SHD with a lithium phosphine or arsine, but this can not involve the problem of geminal substitution. In a preferred embodiment the process is carried out with the aid of LiPR 2 or LiAsR 2 as phosphine or arsine compound, with R representing an alkyl, aryl or aralkyl group. The process according to the invention yields a phosphorus derivative of the formula: or an arsenic derivative of the formula. in which the carbon atoms numbered 1-6 are may be substituted as indicated above. In another preferred embodiment the process according to the invention is carried out with Li 2 PR or Li 2 AsR as phosphorus or arsenic compound. This yields a phosphorus or arsenic derivative having the following formula, respectively: There are a number of routes for the preparation of the starting product SHD, but the synthesis of a large number of SHDs which are in principle suitable for application has not yet been described in the literature. For the preparation of SHD, reference can, for instance, be made to an article by L.G. Menchikov et al. in Russian Chemical Reviews, 63(6), 449-69 (1994), where a number of routes for the preparation of SHDs are indicated. Three main routes are indicated in the article: a) starting from diazocyclopentadiene. About this route it is stated that it has a low yield and a low selectivity and that it is a complex method with explosive starting materials; b) via a cyclomethylenation of the exocyclic double bond in fulvenes. This route as well is rather complex, can only be carried out with very few carbenes (only nucleophile carbenes are suitable for the reaction involved) and may be attended by several side reactions; c) via a cycloalkylation of cyclopentadiene with the aid of 1,2-dibromomethane. This method, which is described for the unsubstituted cyclopentadiene yields the desired SHD with low selectivity when use is made of mono- or polysubstituted cyclopentadienes. Additional drawbacks are that low temperatures are applied (-70°C is mentioned in said article) and that liquid ammonia is used as solvent. The invention is also directed to a process for the preparation of the SHD starting from the corresponding non-geminally substituted β- haloethylcyclopentadiene, which is converted into the corresponding substituted SHD under the influence of a base. In this way the SHD is formed simply and with a high selectivity. As starting product for the process according to the invention use is made of an at least mono-ring- substituted β-haloethylcyclopentadiene of the following formula: where R is hydrogen or the substituents described for the carbon atoms numbered 1-2 in formula (I). The process is also suitable for the preparation of SHDs on the basis of compounds according to formula VI, in which substituents (S) on the cyclopentadienyl ring form part of a ring system. This is found in compounds: a) based on indene, by which compounds of the following formula are meant: R b) based on tetrahydroindene, by which compounds of the following formula are meant: c) the fluorene derivatives of I, including In these as well as in other ring system containing SHD derivatives the C atoms that form part of the cyclopentadienyl, aryl or cyclohexyl ring may also be substituted, with similar groups as mentioned above for compounds of formula I. The cyclopentadiene compound may also be a heterocyclopentadiene. Here and hereinafter the term heterocyclopentadiene refers to a compound which is derived from cyclopentadiene but in which at least one of the C atoms in the 5-ring has been replaced by a hetero atom, the hetero atom having been selected from group 14, 15 or 16 of the Periodic System of the Elements. If more than one hetero atom is present in the 5-ring, these hetero atoms can be either the same or different. More preferably, the hetero atom is selected from group 15, and still more preferably the hetero atom is phosphorus. The reaction is carried out under the influence of a base, which is understood to be a compound capable of abstracting hydrogen (H) (as indicated in formula VI). As base, use may be made, for example, of organolithium compounds (RLi) or organomagnesium compounds (RMgX), where R = an alkyl, aryl or aralkyl group and X = halide (such as, for example, n-butyllithium or isopropylmagnesium chloride). Potassium hydride, sodium hydride, inorganic bases (such as NaOH and KOH), and alcoholates of Li, K and Na can also be used as base. Metallic Na and K are also suitable. Mixtures of the above-mentioned compounds can also be used. In particular the use of a lithiumalkyl compound, and even more preferably the use of n-butyllithium, leads to a high SHD yield. In the process according to the invention it is advantageous if the -Hal group in formula (VI) is a CI group; this gives a high selectivity to the SHD. One way of obtaining compound (VI) is to alkylate the corresponding, at least mono-substituted cyclopentadiene. A problem encountered in such an alkylation is that geminal alkylation takes place, besides the desired non-geminal alkylation. The geminally alkylated products cannot be converted into an SHD. To achieve preferential non-geminal alkylation, the alkylation is carried out under the influence of a Lewis base whose conjugated acid has a dissociation constant for which pK a < -2.5. Such a process yields a substituted cyclo¬ pentadiene in which the carbon atoms of the cyclopentadiene ring, which are substituted, are mainly only mono-substituted (or, in other words: the number of substituted C atoms of the cyclopentadiene increases by 1 as a result of the alkylation, whereas in a geminal substitution the number of substituted C atoms remains the same). The process is therefore suitable for the alkylation of a cyclopentadiene which is at least mono- substituted (in the case of unsubstituted cyclopentadiene, no geminal addition can and will occur); the maximum number of C atoms in the cyclopentadiene substituted before the alkylation is carried out is, on the other hand, 4 (in the case of a cyclopentadiene which is substituted at all 5 C atoms of the ring, only geminal substitution can take place). Preferably, the process is carried out under the influence of one or more weak Lewis bases whose conjugated acid has a pK a of -2.5 to -15, more preferably of -2.5 to -10. Ethers may be mentioned as an example of suitable weak Lewis bases according to the invention. Particularly suitable are: dimethoxyethane (pK a = -2.97), ethoxyethane (pK a = - 3.59), isopropoxyisopropane (pK a = -4.30), methoxymethane (pK, = -3.83), n-propoxy-n-propane (pK a = -4.40), n-butoxy-n-butane (pK a = -5.40), ethoxy-n-butane (pK a = -4.12), methoxybenzene (pK a = -6.54), dioxane (pK a = -2.92). The starting point in this alkylation is the anion of the relevant cyclopentadiene. In order to obtain said anion, H abstraction should take place. This is a technique known per se for which use can be made of a Brønsted base. Suitable for this purpose are hydroxide (such as NaOH, KOH), hydrides (such as KH) , alkylalkali-metal compounds (such as the Li-alkyls, for example n-butyllithium). In this connection, the reaction temperature is not critical, room temperature already being suitable for the purpose. The alkylation reaction is carried out with an alkylating agent. Any compound which can attach a -CH 2 -CH 2 -HAL group to the at least mono-substituted cyclopentadiene is in principle suitable for this purpose. In particular, organohalides and organosulphonyl halides are suitable for this purpose. A particularly suitable sulphonyl alkylhalide, because of its reactivity, is the 2-halo-l(p-toluenesulphonic acid)ethylene having the following structural formula: where: HAL = halide Alkylation with CI as HAL group is also preferred. Such a preferred embodiment increases the selectivity to the alkylated cyclopentadienyl to be obtained. The process according to the invention is usually carried out in a solvent. Any compound of mixture of compounds in which (I) and (VI) are soluble is suitable. Preferably, as solvent a compound is used which exhibits a Lewis base character. This promotes H abstraction by the base. Particularly suitable are ethers, both weak Lewis base ethers (a base whose conjugated acid has a pKa value < -2.5, such as dimethoxyethane and dioxane), and, which is preferred, strong Lewis base ethers (such as tetrahydrofuran (THF) with a corresponding pKa value of -2.0. The process according to the invention is usually carried out at a temperature above -15°C. Room temperature or a slightly higher temperature is already highly suitable for carrying out the process. The pressure is not essentially important, so that the preparation can be carried out already at atmospheric pressure. Of course the presence of interfering components having an adverse effect on the selectivity (such as oxygen, carbon dioxide, water) should be prevented. The alkylation, as described above, does lead preferentially to the non-geminally substituted cyclopentadiene, but it does not do so exclusively. As a consequence, the geminally alkylated cyclopentadienes are also present during the preparation of the SHD. On the one hand there is a small physical difference between the geminal and the non-geminal cyclopentadienes, but on the other there is a large difference between the SHD and the geminal cyclopentadienes. It is therefore to be preferred after formation of the SHD, but before the conversion with the P or As compound, to carry out a separation step to isolate the SHD from the geminally substituted β- haloethyl-cyclopentadiene. As a result, the end product (the P or As derivative according to any of the formulas II-VIII) is (virtually) not contaminated with such geminal products. A separation as meant can be effected by, for example, distillation or column chromatography. De-alkylation of the geminally alkylated cyclopentadienes thus separated seems an option for recycling the cyclopentadienes obtained in the overall process. The reaction with the alkali metal phosphine or -arsine usually takes place in solution. Suitable solvents are generally the same as described for SHD formation. In general equimolar amounts of the required starting products are applied; one skilled in the art is quite capable of determining the optimum ratio between the reactants. The conversion into the phosphorus or arsenic derivative usually takes place at a temperature of -50 to 120°C; more preferably at -20 to 80°C? most preferably the temperature is 0 to 75°C. The P or As derivatives of an at least mon- substituted cyclopentadiene according to the invention are suitable for many applications. In particular they are suitable in a transition metal complex of a transition metal and one or more ligands on the basis of a cyclopentadiene. As ligand one or more of the above-mentioned P or As derivatives according to the invention can be used. This holds more in particular if such a transition metal complex is used as catalyst in a catalyst system for the polymerisation of an α-olefin, in which catalyst system also a co-catalyst is present. In such a situation the transition metal in the complex is chosen from groups 3-6 of the Periodic System of the Elements. The invention therefore also relates to the polymerisation of an α-olefin in which an above- mentioned catalyst system is used. The polymerisation of α-olefins, for example ethylene, propylene, butene, hexene, octene and mixtures thereof and with dienes, can be carried out in the presence of the metal complexes with the cyclopentadienyl compounds according to the invention as ligand. Said polymerisations can be carried out in the manner known for the purpose and the use of the metal complexes as catalyst component does not necessitate any essential adaptation of these processes. The known polymerisations are carried out in suspension, solution, emulsion, gas phase or as bulk polymerisation. An organometallic compound is normally used as co-catalyst, the metal being chosen from groups 1, 2, 12 or 13 of the Periodic System of the Elements. Mention may be made, for example, of trialkylaluminium, alkylaluminium halides, alkylaluminoxanes (such as methylaluminoxanes) , tris(pentafluorophenyl)borate, dimethylanilinium-tetra(pentafluorophenylJborate or mixtures thereof. The polymerisations are carried out at temperatures between -50°C and +350°C, more particularly between 25 and 250°C. The pressures used are generally between atmospheric pressure and 250 MPa, for bulk polymerisations more particularly between 50 and 250 MPa, and for the other polymerisation processes between 0.5 and 25 MPa. As dispersants and solvents, use may be made of, for example, hydrocarbons such as pentane, heptane and mixtures thereof. Aromatic, optionally perfluorinated, hydrocarbons are also suitable. The monomer to be used in the polymerisation may also be used as dispersant or solvent. The invention will be explained in greater detail by reference to the following examples and comparative experiments, without these implying any restriction of the invention. Characterization of the products obtained involved the following analytical methods. Gas chromatography (GC) was carried out on a Hewlett-Packard 5890 series II with an HP crosslinked methyl silicon gum (25 m x 0.32 mm x 1.05 μm) column. Combined gas chromatography/ mass spectrometry (GC-MS) was carried out with a Fisons MD800 equipped with a quadrupole mass detector, autoinjector Fisons AS800 and CPSH8 column (30 m x 0.25 mm x 1 μm , low bleed). NMR was carried out on a Bruker ACP200 (^=200 MHz; 13 C=50 MHz) or Bruker ARX400 ( X H=400 MHz; 13 C=100 MHz). To characterize metal complexes of a Kratos MS80 or alter- natively a Finnigan Mat 4610 mass spectrometer was used. Example I The synthesis of 1,2,3,4-tetramethyl-5(2- chloroethyl)cvclopentadiene A 1 litre three-necked flask provided with a dropping funnel, condenser, mechanical stirrer and nitrogen inlet was filled with 30.5 g of 1,2,3,4- tetramethyl-cyclopentadiene (0.25 mol) dissolved in 700 ml of ethoxyethane and cooled to 2°C. Then 160 ml of n- butyllithium (1.6 M in hexane; 0.26 mol) was added dropwise in the course of 2 hours. Stirring was then carried out for 18 hours at room temperature with the aid of a mechanical stirrer. After that, 36.0 g of 1- bromo-2-chloroethane (0.25 mol) was added in one go. The reaction mixture was stirred for 10 days at room temperature. From GC analysis of a sample, the conversion of the tetramethylcyclopentadiene was found to be 91%. To the reaction mixture, 100 ml of water was added, after which the aqueous phase and the organic phase were separated. The organic layer was washed once with 50 ml of saturated aqueous sodium chloride solution, dried (with sodium sulphate), filtered and evaporated down. The residue (43.9 g) was found from GC analysis to have the following composition: in addition to the original substances l-bromo-2-chloroethane (9% by weight) and 1,2 ,3,4-tetramethylcyclopentadiene (9% by weight), only non-geminally coupled product (84%) and geminally coupled product (16%) were found to be present. Example II The product obtained in Example I (43.9 g), which was found from GC analysis to contain about 32 g of 1,2,3, 4-tetramethyl-5 (2-chloroethyl )cyclopentadiene (0.175 mol), was dissolved in 300 ml of THF. The solution was cooled to -60°C, after which 115 ml of n- butyllithium (1.6 M in hexane; 0.184 mol) was added dropwise. The reaction mixture was brought to room temperature, after which it was stirred for 40 hours. The THF was evaporated off and the residue taken up in 200 ml of ethoxyethane. 100 ml of water was added, after which the water phase and the organic phase were separated. The organic phase was washed once with 100 ml of water. The combined water layer was extracted once with ethoxyethane. The combined organic layer was washed once with 50 ml of saturated sodium chloride solution, dried (sodium sulphate), filtered and evaporated down. The residue (43.2 g) was a pale yellow liquid, which was purified by means of column chromatography (silica gel, petroleum ether as mobile solvent). By means of X H NMR and GC-MS the yield, 24.2 g of colourless liquid, was characterised as being 4,5,6,7-tetramethyl-spiro[2 ,4]-hepta-4,6-diene. The efficiency was 93%, based on the amount of 1,2,3,4- tetramethyl-5-(2-chloroethyl)cyclopentadiene started from, and 65% based on 1,2,3,4-tetramethylcyclo- pentadiene. Example III 3.87 g of diphenylphosphine (21 mmol) was dissolved in 25 ml of THF in a 100 ml reactor and cooled to 2°C. Then 13.0 ml of n-butyllithium (1.6 M in hexane, 21 mmol) was added dropwise and stirring took place for 30 minutes at 2°C. After this, stirring was continued for 1 hour at room temperature. The dark-red mixture obtained was then cooled to -60°C. 3.08 g of 4,5,6,7-tetramethyl-spiro[2,4J-hepta- 4,6-diene (21 mmole), as obtained in Example II, was added in one go. The reaction mixture was brought to room temperature and stirred for 3 days. After this, the THF was evaporated off. The residue, a yellow solid, was washed twice with petroleum ether at 0°C. The solid was then suspended in 50 ml of ethoxyethane, after which 5 ml of water was added dropwise. The ether layer was separated from the water layer. The latter was extracted three times with 25 ml of ethoxyethane. The combined ether layers were then evaporated down, yielding 4.72 g of a light brown, clear viscous liquid. 31 P-NMR and X H-NMR analysis showed the residue to be l,2,3,4-tetramethyl-5(2-P,P-diphenylphosphino- ethyl)cyclopentadiene. The efficiency in terms of 1,2,3,4-tetramethyl-5(2-P,P-diphenylphosphino- ethyl)cyclopentadiene, relative to the 4,5,6,7- tetramethyl-spiro[2,4]-hepta-4,6-diene, was 67%. After GC analysis of the product the purity proved to be >98%. Example IV Lithiumdimethylphosphide was prepared by reaction of dimethylphenylphosphine and lithium, hydrolysis with water, distillation of dimethyl- phosphine and reaction thereof with butyllithium (see Ta-shue Chou et al. in J. Org. Chem. . 50 . , 4329 (1985)). In a 250 ml reactor 8.12 g of lithium¬ dimethylphosphide solution in THF (14 mmol) was mixed with 25 ml of THF. The resulting solution was cooled to -90°C. Then 1.7 g of 4,5,6,7-tetramethyl-spiro[2,4]- hepta-4, 6-diene (12 mmol) as obtained in Example II was added to this solution in one go. The reaction mixture was brought to room temperature and stirred for 2 days. Then, 20 ml of water was added dropwise to the reaction mixture. Subsequently, the THF was evaporated off and the residue was extracted with ether (ethoxyethane). The combined ether layers were evaporated down and the residue was distilled under a vacuum. The boiling point of the residue was 51-52°C (at 0.01 mm Hg) . 31 P-NMR and X H-NMR analysis showed the distilled product (1.13 g) to be mainly 1,2,3,4- tetramethyl-5(2-P,P-diphenylphosphino-ethyl)cyclo¬ pentadiene. The efficiency in terms of 1,2,3,4- tetramethyl-5(2-P,P-diphenylphosphino-ethyl)cyclo- pentadiene, relative to the 4,5,6,7-tetramethyl- spiro[2,4]-hepta-4,6-diene, was 46%. After GC analysis of the product the purity proved to be >95%.

Claims: C L A I M S 1. Process for the preparation of a P or As derivative of an at least bi-substituted cyclopentadiene, characterised in that an at least mono-substituted spiro[2 , 4]-hepta-4 , 6-diene is reacted with an alkali metal phosphine or alkali metal arsine. 2. Process according to claim 1, characterised in that the reaction is carried out using LiPr 2 or LiAsR 2 , each R being hydrogen or an organic group, chosen from the group of alkyl, aryl or aralkyl groups. 3. Process according to claim 2, characterised in that the reaction is carried out using Li 2 Pr or Li 2 AsR. 4. Process according to any one of claims 1-3, characterised in that the spiro[2 , 4]-hepta-4 , 6- diene is obtained by conversion of the corresponding non-geminally substituted β- haloethylcyclopentadiene under the influence of a base. 5. Process according to claim 4, characterised in that the non-geminally substituted β- haloethylcyclo-pentadiene is obtained by alkylation of the corresponding cyclopentadiene using an alkylating agent. 6. Process according to claim 5, characterised in that the alkylation is carried out under the influence of a Lewis base whose conjugated acid has a dissociation constant pK a which is < . -2.5. 7. Process according to either of claims 5-6, characterised in that the spiro[2 ,4]hept-4, 6-diene is separated from the geminally substituted β- haloethylcyclopentadiene before the reaction with the alkali metal phosphine or the alkali metal arsine is carried out. 8. Phosphorus derivative, characterised by formula II. 9. Arsenic derivative, characterised by formula III. 10. Phosphorus derivative, characterised by formula IV. 11. Arsenic derivative, characterised by formula V. 12. Transition metal complex of a transition metal and at least one ligand on the basis of cyclopentadiene, characterised in that the ligand is a P or As derivative of an at least bi- substituted cyclopentadiene according to any one of claims 8-11 or prepared according to any one of claims 1-7. 13. Catalyst system for the polymerisation of an α- olefin comprising a transition metal complex according to claim 12 and a co-catalyst, and the transition metal in the complex being chosen from groups 3-6 of the Periodic System of the Elements. 14. Process for the polymerisation of an α-olefin, characterised in that the polymerisation is carried out under the influence of a catalyst system according to claim 13.

Inventors: ARTS HENRICUS JOHANNES, GRUTER GERARDUS JOHANNES MARIA, VAN BEEK JOHANNES ANTONIUS MAR, ARTS, HENRICUS, JOHANNES, GRUTER, GERARDUS, JOHANNES, MARIA, VAN BEEK, JOHANNES, ANTONIUS, MARIA
Applicants: ARTS HENRICUS JOHANNES, BEEK JOHANNES ANTONIUS MARIA V, DSM NV, GRUTER GERARDUS JOHANNES MARIA, ARTS, HENRICUS, JOHANNES, DSM N.V., GRUTER, GERARDUS, JOHANNES, MARIA, VAN BEEK, JOHANNES, ANTONIUS, MARIA
Application year: 1997
Main classification: C07F9
IPC codes: C07F9, C08F4, C08F10