WO1997042150A1

WO1997042150A1 - Cyclopentadiene compound substituted by branched alkyl groups

Info

Publication number: WO1997042150A1
Application number: PCT/NL1997/000212
Authority: WO
Inventors: Gerardus Johannes Maria Gruter; Johannes Antonius Maria Van Beek; Richard Green; Matthijs Van Kessel
Original assignee: Dsm N.V.
Priority date: 1996-05-03
Filing date: 1997-04-23
Publication date: 1997-11-13
Also published as: AU2409097A; NL1003006C2

Abstract

Polysubstituted cyclopentadiene compound of which at least two substituents are branched C5-, C6- or C7-alkyl groups, and use thereof for preparing a metal complex in a polar solvent. The metal complex, wherein at least one substituted cyclopentadiene compound in which at least two substituents are branched alkyl groups is present as a ligand, can be used as a catalyst component in the polymerization of α-olefins.

Description

CYCLOPENTADIENE COMPOUND SUBSTITUTED BY BRANCHED ALKYL GROUPS

The invention relates to a polysubstituted cyclopentadiene compound. Cyclopentadiene compounds, both substituted and unsubstituted, are used widely as a starting material for preparing ligands in metal complexes having catalytic activity.

In J. of Organomet. Chem., 479 (1994), 1-29 an overview is provided of the influence of the substituents on cyclopentadiene as a ligand in metal complexes. Here it is observed, on the one hand, that the chemical and physical properties of metal complexes can be varied over a wide range by the specific choice of the substituents on the cyclopentadiene ring. On the other hand, it is stated that no predictions can be made concerning the effect to be expected of specific substituents. In the great majority of cases, either unsubstituted cyclopentadiene or cyclopentadiene substituted by one to five methyl groups is used. These metal complexes are mostly synthesized in polar solvents of which ethers, inter alia tetrahydrofuran, THF, are known examples.

Hereinafter, cyclopentadiene will be abbreviated as Cp. The same abbreviation will be used for a cyclopentadienyl group if it is clear, from the context, whether cyclopentadiene itself or its anion is meant.

A drawback of many of the known substituted Cp compounds is that a metal complex in which known Cp compounds are present as a ligand is only moderately soluble in polar solvents, which hampers the preparation of metal complexes containing the substituted Cp compounds.

The object of the invention is to provide substituted Cp compounds whose metal complexes have improved solubility in polar solvents.

This object is achieved, according to the invention, by at least two of the substituents being branched C₃-, C₆- or C₇-alkyl groups.

The presence of at least two of such branched alkyl groups instead of hydrogen or methyl groups is found to entail improved solubility in polar solvents. In general, the reason why compounds are provided with larger hydrocarbon substituents, which also include the branched alkyl groups, is to improve their solubility in apolar solvents.

A further advantage of the Cp-compounds according to the invention is that during further substitution of these Cp-compounds less geminal substitution occurs. This is an advantage when one wants to include a further substituted Cp-compound in a metal complex.

The branched^' alkyl groups can be either identical or different. Particularly suitable branched alkyl groups are, for example, 2-pentyl, 2-hexyl, 2- heptyl, 3-pentyl, 3-hexyl, 3-heptyl, 2-(3-methylbutyl) , 2-(3-methylpentyl) , 2-(4-methylpentyl ) , 3-(2- met-hylpentyl ) , 2-(3 , 3-dimethylbutyl ) , 2-(3- ethylpentyl) , 2-(3-methylhexyl) , 2-(4-methylhexyl) , 2- (5-methylhexyl) , 2-(3 , 3-dimethylpentyl ) , 2-(4,4- dimethylpentyl), 3-(4-methylhexyl ) , 3-(5-methylhexyl ) , 3-(2,4-dimethylpentyl) , 3-(2-methylhexyl ) , 3-(4,4- dimethylpentyl) , l-(2-ethylbutyl) , l-(2-methyl-3- chloropropyl ) , 2-(l-chloropropyl ) , l-(3-methylbutyl ) , 4-(2-methylbutenyl ) , l-(2-methylpropyl) , l-(2- ethylbutyl), l-(3-chloro-2-methylpropyl ) , 2-(l- chloropropyl ) , l-(2-methylbutenyl) and l-(2- methylpropyl) . Preferably, the Cp compound according to the invention contains 2, 3 or 4 branched alkyl groups as substituents. These branched alkyl groups do not contain any hetero atoms from group 16 of the Periodic System of the Elements.

In addition to these branched alkyl groups whose presence is required within the scope of the invention, the Cp compound may also contain further substituents. Examples of these are alkyl groups, both linear and branched, and cyclic, alkenyl and aralkyl groups. It is also possible for these to contain, apart from carbon and hydrogen, one or more hetero atoms from the groups 14-17 of the Periodic System of the Elements, for example 0, N, Si or F, a hetero atom not being bound directly to the Cp. Examples of suitable groups are methyl, ethyl, (iso)propyl, sec-butyl, cyclohexyl, benzyl.

Substituted Cp compounds can, for instance, be prepared by reacting a halide of the substituting compound in a mixture of Cp compound and an aqueous solution of a base in the presence of a phase transfer catalyst. The term Cp compounds here refers to Cp itself and Cp already substituted in 1 to 3 positions, with the option of two substituents forming a closed ring. By means of the method according to the invention it is thus possible to convert unsubstituted compounds into singly or multiply substituted ones, but it is also possible for mono- or polysubstituted compounds derived from Cp to be substituted further, ring closure also being included in the options.

Preferably, a virtually equivalent quantity with respect to the Cp-compound of the halogenated substituting compound is used. An equivalent quantity is understood as a quantity in moles which corresponds to the desired substitution multiplicity, for example 2 mol per mole of Cp compound, if disubstitution with the - 4 -

substituent in question is intended.

Depending on the size and the associated steric hindrance of the substituting compounds it is possible to obtain trisubstituted to hexasubstituted Cp compounds. If a reaction with a tertiary halide of a substituting compound is carried out, as a rule only trisubstituted Cp compounds can be obtained, whereas with a primary and secondary halide of a substituting compound it is generally possible to achieved tetra and often even penta- or hexasubsti- tution.

The substituents are preferably used in the method in the form of their halides and more preferably in the form of their bromides. If bromides are used a smaller quantity of phase transfer catalyst is found to be sufficient, and a higher yield of the compound aimed for is found to be achieved.

By means of this method it is also possible, without intermediate isolation or purification, to obtain Cp compounds which are substituted by specific combinations of substituents. Thus, for example, disubstitution with the aid of a certain halide of a substituting compound can first be carried out and in the same reaction mixture a third substitution by a different substituent can be carried out, by adding a second, different halide of a substituting compound being added to the mixture after a certain time. This can be repeated, so that it is also possible to prepare Cp derivatives having three or more different substituents. The substitution takes place in a mixture of the Cp compound and an aqueous solution of a base. The concentration of the base in the solution is in the range between 20 and 80 wt.%. Hydroxides of an alkali metal, for example K or Na are highly suitable as a base. The base is present in an amount of 5-60 mol, preferably 6-30 mol, per mole of Cp compound. It was found that the reaction time can be considerably shortened if the solution of the base is refreshed during the reaction, for example by first mixing, the solution of the base with the other components of the reaction mixture and after some time separating the aqueous phase from the reaction mixture and replacing it by a fresh quantity of the solution of the base. The temperature at which the reaction takes place can vary between wide limits, for example from -20 to 120°C, preferably between 10 and 50°C. Initiating the reaction at room temperature is suitable, as a rule, whereupon the temperature of the reaction mixture may rise as a result of the heat liberated in the course of the reaction occurring. The substitution takes place in the presence of a phase transfer catalyst which is able to transfer OH-ions from the aqueous phase to the organic phase containing Cp compound and halide, the OH-ions reacting in the organic phase with a H-atom which can be split off the Cp compound. The organic phase contains the Cp compound and the substituting compound. Possible phase transfer catalysts to be used are quaternary ammonium, phosphonium, arsonium, stibonium, bismuthonium, and tertiary sulphonium salts. More preferably, ammonium and phosphonium salts are used, for example tricaprylmethylammonium chloride, commercially available under the name Aliquat 336 (Fluka AG, Switzerland; General Mills Co. , USA) and Adogen 464 (Aldrich Chemical Co., USA). Compounds such as benzyltriethylammonium chloride (TEBA) or benzyltriethylammonium bromide (TEBA-Br), benzyltrimethylammonium chloride, benzyltrimethylammonium bromide or benzyltrimethyl¬ ammonium hydroxide (Triton B), tetra-n-butylammonium chloride, tetra-n-butylammonium bromide, tetra-n-butyl¬ ammonium iodide, tetra-n-butylammonium hydrogen sulphate or tetra-n-butylammonium hydroxide and cetyltrimethylammonium bromide or cetyltrimethylammonium chloride, benzyltributyl-, tetra-n-pentyl-, tetra-n-hexyl- and trioctylpropylammonium chlorides and their bromides are likewise suitable. Usable phosphonium salts include, for example, tributylhexadecylphosphonium bromide, ethyltriphenylphosphonium bromide, tetraphenylphosphonium chloride, benzyltriphenylphosphonium iodide and tetrabutyl- phosphonium chloride. Crown ethers and cryptands can also be used as a phase transfer catalyst, for example 15-crown-5, 18-crown-6, dibenzo-18-crown-6, dicyclohexano-18-crown-6, 4,7,13,16,21-pentaoxa-l,10- diazabicyclof8.8.5]tricosane (Kryptofix 221),

4,7,13,18-tetraoxa-l,10-diazabicyclo[8.5.5]eicosane (Kryptofix 211) and 4,7,13,16,21,24-hexaoxa-l,10- diazabicyclo[8.8.8]-hexacosane ("[2.2.2]") and its benzo derivative Kryptofix 222 B. Polyethers such as ethers of ethylene glycols can also be used as a phase transfer catalyst. Quaternary ammonium salts, phosphonium salts, phosphoric acid triamides, crown ethers, polyethers and cryptands can also be used on supports such as, for example, on a crosslinked poly- styrene or another polymer. The phase transfer catalysts are used in an amount of 0.01 - 2, preferably 0.05 - 1 equivalents on the basis of the amount of Cp- compound.

In the implementation of the method the components can be added to the reactor in various sequences.

After the reaction is complete, the aqueous phase and the organic phase which contains the Cp compound are separated. When necessary, the Cp compound is obtained from the organic phase by fractional distillation. This method can be used to obtain Cp compounds bi-, tri-, tetra- and pentasubstituted by the desired branched alkyl.

The substituted Cp compounds according to the invention are particularly suitable as a ligand in a metal complex, and the invention therefore also relates to the use of a cyclopentadiene compound substituted by at least two branched alkyl groups, for preparing a metal complex in a polar solvent. These metal complexes have better thermal stability than complexes containing Cp ligands which are not substituted by branched groups.

Metal complexes which are catalytically active if one of their ligands is a compound according to the invention are complexes of metals from groups 4- 10 of the Periodic System of the Elements and rare earths. In this context, complexes of metals from groups 4 and 5 are preferably used as a catalyst component for polymerizing olefins, complexes of metals from groups 6 and 7 in addition also for metathesis and ring-opening metathesis polymerizations, and complexes of metals from groups 8-10 for olefin copolymerizations with polar comonomers, hydrogenations and carbonylations. For the Periodic System, see the new IUPAC notation to be found on the insdie of the cover of the Handbook of Chemistry and Physics, 70th edition, 1989/1990.

Particularly suitable for the polymerization of olefins are such metal complexes in which the metal is chosen from the group consisting of Ti, Zr, Hf, V and Cr.

The term olefins here and hereinafter refers to α-olefins, diolefins and other ethylenically unsaturated monomers. Where the term 'polymerization of olefins' is used, this hereinafter refers both to the polymerization of a single type of olefinic monomer and to the copolymerization of two or more olefins.

The synthesis of metal complexes containing the above-described specific Cp compounds as a ligand may take place according to the methods known per se for this purpose. The use of these Cp compounds does not require any adaptations of said known methods.

The synthesis of metal complexes containing the above-described specific Cp compounds as a ligand in polar solvents and other types of solvent may take place according to the methods known per se for this purpose. The use of these Cp compounds does not require any adaptations of said known methods.

The polymerization of α-olefins, for example ethene, propene, butene, hexene, octene and mixtures thereof and combinations with dienes can be carried out in the presence of the metal complexes containing the cyclopentadienyl compounds according to the invention as a ligand. Particularly suitable for this purpose are the complexes of transition metals, not in their highest valence state, in which just one of the cyclopentadienyl compounds according to the invention is present as a ligand, and in which the metal during the polymerization is cationic. These polymerizations can be carried out in the manner known for this purpose, and the use of the metal complexes as a catalyst component does not require any significant adaptation of these methods. The known polymerizations are carried out in suspension, solution, emulsion, gas phase or as a bulk polymerization. It is customary to use, as a cocatalyst, an organometallic compound, the metal being selected from group 1, 2, 12 or 13 of the Periodic System of the Elements. Examples to be mentioned include trialkylaluminium, alkylaluminium halides, alkylaluminoxanes (such as methylaluminoxanes) , tris(pentafluorophenyl) borane, dimethylanilinium tetra(pentafluorophenyl) borate or mixtures thereof. The polymerizations are carried out at temperatures between -50°C and +350°C, more in particular between 25 and 250°C. Pressures used are generally between atmospheric pressure and 250 MPa, for bulk polymerizations more in particular between 50 and 250 MPa, for the remaining polymerization processes between 0.5 and 25 MPa. Dispersing agents and solvents to be used include, for example, hydrocarbons such as pentane, heptane and mixtures thereof. Aromatic, optionally perfluorinated hydrocarbons likewise deserve consideration. Equally, the monomer to be employed in the polymerization can be used as a dispersing agent or solvent. The invention will be explained with reference to the following examples, but is not limited thereto.

Characterization of the products obtained involves 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 0.3'2 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 CPSilδ column (30 m x 0.25 mm x 1 μm, low bleed). NMR was carried out on a Bruker ACP200 (^XH=200 MHz; ¹³C=50 MHz) or Bruker ARX400 (¹H=400 MHz; ¹³C=100 MHz). To characterize metal complexes, use was made of a Kratos MS80 or alternatively a Finnigan Mat 4610 mass spectrometer.

Example I

Preparation of di(cyclohexyl)cvcloρentadiene A double-walled reactor having a volume of 1

L, provided with baffles, condenser, top stirrer, thermometer and dropping funnel was charged with 600 g of clear 50% strength NaOH (7.5 mol), followed by cooling to 8°C. Then 20 g of Aliquat 336 (49 mmol) and 33 g (0.5 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was stirred turbulently for a few minutes. Then 172 g of cyclohexyl bromide (1.05 mol) were added, cooling with water taking place at the same time. After 2 hours' stirring at room temperature the reaction mixture was warmed to 70°C, followed by a further 6 hours' stirring. GC was used to show that at that instant 79% of di (cyclohexyl)cyclopentadiene were present. The product was distilled at 0.04 mbar and 110-120°C. After distillation, 73.6 g of di (cyclohexyl )cyclopentadiene were obtained. Characterization took place with the aid of GC, GC-MS, ¹³C- and ^-NMR.

Example II

Preparation of di- and tri (3-pentyl )cyclopentadiene A double-walled reactor having a volume of 1

L, provided with baffles, condenser, top stirrer, thermometer and dropping funnel was charged with 430 g (5.4 mol) of clear 50% strength NaOH. Then 23 g of Aliquat 336 (57 mmol) and 27 g (0.41 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was stirred turbulently for a few minutes. Then 150 g of 3-pentyl bromide (1.0 mol) were added over a period of 1 hour cooling with water taking place at the same time. After 1 hour's stirring at room temperature the reaction mixture was warmed to 70°C, followed by a further 3 hours' stirring. Stirring was stopped and phase separation was awaited. The water layer was drawn off and 540 g (6.70 mol) of fresh 50% strength NaOH were added, followed by a further 4 hours' stirring at 70°C. GC was used to show that at that instant the mixture consisted of di- and tri(3- pentylJcyclopentadiene (approximately 3 : 2). The products were distilled at 0.2 mbar, 51°C and 0.2 mbar, 77-80°C, respectively. After distillation, 32 g of di- and 18 g of tri(3-pentyl)cyclopentadiene were obtained. Characterization took place with the aid of GC, GC-MS, ¹³C-and ^XH-NMR.

Example III

Preparation of tri(cyclohexyl)cyclopentadiene A double-walled reactor having a volume of 1

L, provided with baffles, condenser, top stirrer, thermometer and dropping funnel was charged with 600 g of clear 50% strength NaOH (7.5 mol), followed by cooling to 8°C. Then 20 g of Aliquat 336 (49 mmol) and 33 g (0.5 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was stirred turbulently for a few minutes. Then 256 g of cyclohexyl bromide (1.57 mol) were added, cooling with water taking place at the same time. After 1 hour's stirring at room temperature the reaction mixture was warmed to 70°C, followed by a further 2 hours' stirring. After 2 hours, stirring was stopped and phase separation was awaited. The water layer was drawn off and 600 g (7.5 mol) of fresh 50% strength NaOH were added, followed by a further 4 hours' stirring at 70°C. GC was used to show that at that instant 10% di- and 90% tri(cyclohexyl)cyclo- pentadiene were present in the mixture. The product was distilled at 0.04 mbar and 130°C. After distillation, 87.4 g of tri(cyclohexyl)cyclopentadiene were obtained. Characterization took place with the aid of GC, GC-MS, ¹³C-and Η-NMR.

Example IV

Preparation of di- and tri (2-pentyl)cyclopentadiene A double-walled reactor having a volume of 1

L, provided with baffles, condenser, top stirrer, thermometer and dropping funnel was charged with 900 g (11.25 mol) of clear 50% strength NaOH. Then 31 g of Aliquat 336 (77 mmol) and 26.8 g (0.41 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was stirred turbulently for a few minutes. Then 155 g of 2-pentyl bromide (1.03 mol) were added over a period of 1 hour cooling with water taking place at the same time. After 3 hours' stirring at room temperature the reaction mixture was warmed to 70°C, followed by a further 2 hours' stirring. Stirring was stopped and phase separation was awaited. The water layer was drawn off and 900 g (11.25 mol) of fresh 50% strength NaOH were added, followed by a further two hours' stirring at 70°C. GC was used to show that at that instant the mixture consisted of di- and tri (2- pentyl )cyclopentadiene (approximately 1 : 1). The products were distilled at 2 mbar, 79-81°C and 0.5 mbar, 102°C, respectively. After distillation, 28 g of di-and 40 g of tri (2-pentyl)cyclopentadiene were obtained. Characterization took place with the aid of GC, GC-MS, ¹³C- and ^-NMR.

Claims

C L A I M S

1. Polysubstituted cyclopentadiene compound, characterized in that at least two substituents are branched C₅-, C_β- or C₇-alkyl groups, with the exception of di- and tricyclohexylcyclopentadiene.

2. Polysubstituted cyclopentadiene compound according to claim 1, characterized in that the Cp compound contains 2, 3 or 4 branched C₅-, C₆- or C₇-alkyl groups.

3. Use of substituted cyclopentadiene compound according to Claim 1 or 2 for preparing a metal complex in a polar solvent.

4. Metal complex which contains at least one substituted cyclopentadiene compound according to

Claim 1 or 2 as a ligand.

5. Use of a metal complex wherein at least one substituted cyclopentadiene compound, in which at least two substituents are branched alkyl groups, is present as a ligand, as a catalyst component in the polymerization of α-olefins.