ITTO960601A1 - SYNDIOSPECIFIC METALLOCENE ADDUCT CATALYST - Google Patents

Description

DESCRIPTION of the industrial invention entitled: "Syndiospecific metallocene adduct catalyst"

Field of the invention

The present invention refers to a metallocene adduct catalyst for the preparation of syndiotactic polyolefins, particularly syndiotactic polypropylene, to a process for the preparation of the catalyst and to the use of the catalyst in the polymerization of the olefin.

Background of the invention

It was first found by J. A. Ewen et al. that a syndiotactic polypropylene with pentadic syndiotacticity of 70% can be obtained using a catalyst system consisting of a compound of a transition metal with a ligand having Cs symmetry and an aluminoxane. Typical examples of said transition metal compounds are isopropylidene dichloride (cyclopentadienylfluorenyl) zirconium and isopropylidene dichloride (cyclopentadienyl-fluorenyl) hafnium (J. Am. Chem. Soc., 110, 6255-6256 (1988)). Also disclosed in the patents are some compounds of similar transition metals, for example, methylphenylmethylene dichloride (cyclopentadienyl-fluorenyl) zirconium, diphenylmethylenic cyclopentadienyl-fluorenyl) zirconium dichloride, and diphenylmethylene dichloride (cyclopentadienylfluorenyl, etc.). (reference to EP 387690, EP 387691, EP 0516019A2).

The above transition metal compounds are generally prepared by first reacting the fluorene with a disubstituted fulvene to obtain a metallocenyl ligand, which is reacted with either zirconium tetrachloride or hafnium tetrachloride. Fluorene should first be converted to its anionic form to facilitate its reaction with the disubstituted fulvene. The most commonly used is fluorenyllithium, which is generally obtained by the reaction of fluorene with a solution in diethyl ether of equimolar methyllium or a solution of hexane of equimolar butyllithium.

The used methyl ether solution of methyl ether is obtained by the reaction of methyl iodide and lithium metal at a relatively low temperature (-10 ° C). the yield of which is relatively low due to the unavoidable coupling reaction of the methyl radical during the reaction. Furthermore, the cost is high as methyl iodide as a starting material is very expensive. The butyllithium hexane solution is more chemically active, however, if the drop rate and temperature regulation is not applied, a reaction occurs between the butyllithium in the overconcentrated point and the other relatively active hydrogen or a single transfer occurs. electron (SET) to form radicals so that the unity of the reaction cannot be maintained, leading to the lowering of the conversion of the reaction.

The addition reaction of fulvene substituted with dialkyl and fluorenyllithium is generally carried out at -78 ° (CN 1040036A) since an elimination reaction tends to occur on the coactive hydrogens contained in alkylfulvene in the presence of strong basic fluorenyllithium and this elimination reaction can be suppressed at a low temperature due to its dynamically predominant nature. In contrast to fulvene substituted with dialkyl, fulvene substituted with diaryl does not contain acidic hydrogen and the addition reaction of the fluorene anion on the double bond external to the fulvene ring can be carried out under mild conditions (EP 0516019A2).

Two procedures for carrying out the reaction between the ligand dianion and zirconium tatrachloride

are described in CN 1040036A. One is the

pretreatment of with tetrahydrofuran (THF) to form and its reaction with the ligand dianion. The yield of zirconocene is 30-40% and the THF binds in the catalyst of the final complex compound. Another is the mixing of the

in methylene chloride at -7S ° C and the reaction of the slurry with a solution of methylene chloride of the anion of the ligand at -78 ° C. The yield of zirconocene is typically 40-50%.

A process for the preparation of diphenylmethylene dichloride (cyclopentadienyl-9-fluorenyl) -zirconium is described in detail in EP 0516019A2, in which the fluorene anion is obtained by reacting the fluorene with equimolar n-butyllithium and the fluorenyllithium reacts with the disubstituted fulvene at room temperature to give 42% metallocenyl ligand; then the metallocenyl ligand reacts with THF at - 78 ° C in order to obtain only 36% zircocane.

Such metallocene catalysts as mentioned above are indispensable for the preparation of syndiotactic polyolefin, but they are very inconvenient for practical use due to their severe preparation conditions, low yield, complicated purification process (they need to be isolated by removing the solvent under vacuum and purified by extraction with alkanes or recrystallized by aromatic hydrocarbons or by chromatography using ion exchangers), as well as by their poor stability in air (they also gradually decompose into nitrogen).

An object of the invention is to provide a much more stable metallocene catalyst than those of the prior art.

Another object of the invention is to provide a process for the preparation of the metallocene catalyst under mild conditions and with high yield without purification.

The third object of the invention is to provide the use of the metallocene catalyst in the preparation of syndiotactic polyolefin.

We have found that fluorenyl lithium can be obtained with a high yield by reacting phenyl lithium instead of methyl lithium and butyl lithium in the prior art with fluorene. The reaction between phenyl and fluorene proceeds stably and a stoichiometric reaction can be completed after 4 hours. at room temperature.

We have also found that the solid product obtained by the reaction of the ligand dianion and the in a weak Lewis base medium such as diethyl ether has good activity as a syndiotactic polymerization catalyst, and it can be used as a catalyst without purification. Furthermore, it can be present with short stability in the air.

The present invention is completed on the basis of the above findings.

Summary of the invention

The catalyst provided by the invention for the preparation of synotactic polyolefin is a three-component adduct of inorganic metallocene-ether-salt having the following general formula:

wherein Ar represents an unsubstituted or substituted aryl; Cp represents an unsubstituted or substituted cyclopentadienyl whose substituents are selected from the group consisting of alkyl

alkoxy, silanyl, aryl, aralkoxyl, hydroxyl and halogen; Flu represents an unsubstituted or substituted fluorenyl whose substituents are selected from the group consisting of alkyl alkoxy, silyl, aryl, aralkoxyl, hydroxyl and halogen; he represents an element chosen from among those of the IVB group of the Periodic Table; Q represents halogen, alkyl, alkoxy, aromatic fused ring group or heterocyclic group; R and R 'are the same or different and selected from alkyl * represents oxygen or sulfur; Me 'represents an alkali metal or an alkaline earth metal, and n represents 1 or 2.

The present invention also provides a process for the preparation of the catalyst comprising:

(1) reaction of substituted or unsubstituted fluorene with a strong base in an ethereal solvent and reaction of the resulting anion of fluorene with a substituted or unsubstituted diarylfulvene on the ring at room temperature, so as to form a metallocenyl ligand;

(21 reaction of the metallocenyl ligand with an alkaline reagent in an inert solvent, and reaction of the resulting dianion of the metallocenyl ligand with a metal compound of the formula in which Me is a metal selected from those of group IVB of the Periodic Table, and Q is selected from the group consisting of halogen, alkyl, alkoxy, aromatic fused ring group and heterocyclic group.

In a further aspect of the invention, a process is provided for the preparation of a syndiotactic polyolefin comprising the polymerization of an olefin using the catalyst provided by the present invention as the main catalyst in combination with a cocatalyst selected from the group consisting of methylaluminium nooxane. a mixture of alkylaluminium and methylaluminoxane and an organic boron compound. Detailed description of the invention

The present invention provides a metallocele catalyst for the preparation of syndiotactic polyolefin, which is a three-component adduct of inorganic metallocene-ether-salt having the following general formula:

in which

Ar represents an unsubstituted or substituted aryl such as phenyl, aromatic fused ring group or heterocyclic group such as naphthyl, pyridyl, etc., preferably phenyl;

Cp represents an unsubstituted or substituted cyclopentadienyl whose substituents are selected from the group consisting of alkyl alkoxy, silyl, aryl, aralkoxyl, hydroxyl and halogen;

Flu represents an unsubstituted or substituted fluorenyl whose substituents are selected from the group consisting of alkyl alkoxy, silyl, aryl, aralkoxyl, hydroxyl and halogen;

Me represents an element selected from those of the IVB group of the Periodic Table, preferably zirconium and hafnium, particularly zirconium;

Q represents halogen, alkyl, alkoxy, aromatic ring group or heterocyclic group, preferably halogen, particularly chlorine;

R and R 'are the same or different and selected from preferably ethyl alkyl;

X represents oxygen or sulfur, preferably oxygen;

Me 'represents an alkali metal or an alkaline earth metal preferably lithium, magnesium, particularly lithium; And

n has the value of 1 or 2, and n is 1 when Me 'represents an alkali metal and 2 when Me' represents an alkaline earth metal.

Analysis by X-ray diffraction on the metallocene adduct sample provided by the invention shows that the catalyst has a certain degree of crystallinity. An obvious characteristic peak of RXR is observed from the spectrum, and it is demonstrated by element analysis that the complex metallocene catalyst has the composition of formula

Where it is

extracted with a solvent that easily dissolves the metallocene such as methylene dichloride, toluene and the like, the resulting metallocene becomes very sensitive to air, demonstrating the intermolecular forces between the three components of the catalyst, which increase the stability of the metallocene. As shown by the following description, components other than the metallocene do not have an adverse effect on the polymerization of the olefin in addition to the stabilization of the metallocene.

The process for the preparation of the above catalyst provided by the present invention comprises:

(1) reaction of the substituted or unsubstituted fluorene with a strong base in an ethereal solvent and reaction of the resulting anion of fluorene with a substituted or unsubstituted diarylfulvene on the ring at room temperature, so as to form a metallocenyl ligand;

2) reaction of the metallocenyl ligand with an alkaline reagent in an inert solvent, and reaction of the resulting dianion of the metallocenyl ligand with a metal compound of formula in which Me is a metal selected from those of the IVB group of the Periodic Table, and Q is selected from group consisting of halogen, alkyl, alkoxy, aromatic fused ring group and heterocyclic group.

In step (1) the ether solution can be any of those commonly used in the art, such as tetrahydrofuran, diethyl ether. The strong base used can be alkylthium such as methylthium, butyllithium, or it can be arylthium such as phenyllithium, and phenyllithium is preferably used in the present invention. Examples of the substituents on the fluorene and diarylfulvene rings are alkyl alkoxy, silyl, aryl, aralkoxyl, hydroxyl, halogen and the like. The preferable diarylfulvene is dipheniliulvene.

In step (2) the inert solvent is selected from those represented by the formula RXR ', in which R and R' are the same or different, and are selected from alkyl

preferably ethyl; X represents oxygen

or sulfur, preferably oxygen. Diethyl ether is preferably used in the present invention. The alkaline reagent can be commonly used alkyl or aryl lithium, etc., and butyl lithium is generally used. Among the metal compounds of formula Me it is preferably zirconium and hafnium, particularly zirconium; Q is preferably halogen, particularly chlorine.

The process for the preparation of the syndiotactic polyolefin using the above metallocene adduct as the catalyst provided by the present invention comprises the polymerization of an olefin using the catalyst provided by the present invention as the main catalyst in combination with a cocatalyst selected from the group consisting of methylaluminoxane, a mixture of alkylaluminium and methylaluminoxane, and an organic boron compound to form syndiotactic polyolefin. Methylaluminooxane is preferably used as cocatalyst. The ratio of the quantity of cocatalyst to the quantity of the main catalyst used is suitably about 300 in A1 / Zr (moles).

Said olefin can be ethylene or

olefin preferably propylene.

The polymerization can be carried out by any process known in the art, preferably by a solution polymerization process or a slurry polymerization process. The solvent used can be an aliphatic or aromatic hydrocarbon such as hexane, toluene.

The metallocene adduct provided by the present invention is much more stable than those of the prior art, and it can be exposed to the air for several hours or stored under nitrogen for a long period without losing its activity. Furthermore, a zirconocene can be prepared with a high yield of about 85% under mild conditions without complicated purification. A syndiotactic polyolefin with good properties can be obtained by polymerization of the olefin using the catalyst of the invention as the main catalyst and methylaluminoxane as a cocatalyst with a relatively low A1 / Zr ratio,

Brief description of the drawings

Figure 1 is the spectrum of. polypropylene obtained in Example 2.

Figure 2 is the IR spectrum of the polypropylene obtained in Example 2.

Examples

The following preferred examples are provided to further illustrate the invention but are not intended in any way to limit the scope of the invention.

Example 1

Preparation of the

5.10 g (30.7 mmol) of fluorene was introduced into a 250 ml Schlenk flask, which was dissolved in 60 ml of anhydrous tetrahydrofuran (THF) before 38.4 ml (30.7 mmol) of phenyllithium 0.8 M in diethyl ether were introduced through a constant pressure funnel, and the reaction was allowed to proceed for 2 hours. Then 7.07 g (30.7 mmol) of diphenylfulvene was introduced and the reaction was allowed to proceed for 12 hours. An appropriate amount of water was added to the reaction mixture for hydrolysis. The organic phase was separated and concentrated under vacuum, and the residue was recrystallized from a mixture of methanol and chloroform giving 6.2 g (yield 51%) of metallocenyl ligand in the form of a white powder, which has the following composition and structure as reported by the elementary analysis and the NMR:

2.0 g (5.0 mmoles) of the ligand thus obtained were dissolved in 20 ml of a mixture of diethyl ether and hexane (v / v = 1/1), to which 6.4 ml (10 mmoles) were added ) of a 1.6M solution of butyllithium in hexane. After reaction at room temperature for 15 hours, the resulting suspension was cooled to -50 ° C, and 1.16 g (5.0 mmol) of was added. The mixture was stirred at room temperature and filtered, giving 3. 1 g of catalyst referred to in the title in the form of solid powder.

Analysis by X-ray diffraction showed that the catalyst has a certain degree of crystallinity. Electron microscopy shows that elementary Zr and Cl are uniformly distributed in the region to be analyzed. An obvious characteristic peak of is observed from the <1> H -NMR spectrum

(diethyl ether). It is demonstrated by elementary analysis that it has a composition of

And it is shown in spectroscopy

induced coupling plasma atomic emission (ICP-AES) that the catalyst contains 11% by weight of Zr, therefore its yield is 1'85% with respect to the weight of Zr.

Example 2

Polymerization of propylene under atmospheric pressure

A 500 ml three-necked flask previously purged with high purity nitrogen was loaded with 100 ml of toluene, 50 mg of the catalyst prepared in Example 1 and 2 g of methylaluminoxane under the propylene atmosphere. The propylene gas was continuously introduced and the polymerization was allowed to proceed under atmospheric pressure for 3 hours, giving 5.2 g (after drying) of propylene, which was subjected to IR, DSC (Differential Scanning Calorimetry) and GPC (gel permeation chromatography).

The chemical shift of the shown in the spectrum

(fig. 1) and the characteristic peaks at 977 cm-1 and 963 cm <-1> shown in the IR spectrum (fig. 2) demonstrate that polypropylene is syndiotactic and its triadic syndiotacticity (rr%) is greater than 80% as assumed by the <13> C-NMR spectrum. Propylene has a melting point of 107 ° 0 as determined by DSC, a weight average molecular weight (Mw) of 220,000, and a molecular weight distribution (MWD) of 2 as determined by GPC.

Example 3

Polymerization of propylene under high pressure A 1 liter autoclave previously purged with high purity nitrogen was loaded with 400 ml of toluene. After the toluene was saturated with propylene gas, 2.0 g of methylaluminoxane and 0.100 g of the catalyst prepared in Example 1 were added. The reaction was allowed to proceed at 35 ° C for one hour while maintaining the monomer pressure. at 0.7 MPa, and then was stopped by adding a small amount of acidic methanol. Ethanol was added to precipitate the polymer which was washed with ethanol and dried in vacuum, giving 10 g of polypropylene. Polypropylene has a melting point of 139 ° C determined by DSC, a Mw of 450,000 and a MWD of 2.29 determined by GPC, and a syndiotacticity of (rr + rrr + rrrr)% greater than 92%

Example 4

Liquid phase mass polymerization of polypropylene under high pressure

50 mg of the catalyst prepared in Example 1 and 2 g of methylaluminooxane were dissolved in 30 ml of toluene and the mixture was left in pre-contact for two hours.

A 5-liter autoclave previously purged with high-purity nitrogen was charged with 20 ml of a solution of 1 g of methylaluminoxane in toluene, followed by the aforementioned pre-contacted liquid and 3 liters of liquid propylene. The system was raised to 70 ° C and the polymerization was carried out for one hour at 70 ° C and 2.9 MPa with stirring at 250 rpm. The reaction was stopped and the excess propylene was discharged, giving a polymer powder, which was subsequently washed with a solution of methanol and diluted HCl and ethanol and dried, giving syndiotactic polypropylene (characterized by Polypropylene has a Mw of 410,000 and a MWD of 2.3 determined by GPC and a melting point of 139 ° C determined by DSC.

Claims (1)

CLAIMS 1. - Syndiospecific metallocene catalyst, characterized in that said catalyst is an adduct to between components of inorganic metallocene-ether-salt having the following general formula: wherein Ar represents an unsubstituted or substituted aryl; Cp represents an unsubstituted or substituted cyclopentadienyl whose substituents are selected from the group consisting of alkyl alkoxy, silyl, aryl, aralkoxyl, hydroxyl and halogen; Flu represents an unsubstituted or substituted fluorenyl whose substituents are selected from the group consisting of alkyl alkoxy, silyl, aryl, aralkoxyl, hydroxyl and halogen; Me represents an element selected from those of group IVB of the Periodic Table, Q represents halogen, alkyl, alkoxy, aromatic fused ring group or heterocyclic group; R and R 'are the same or different and selected from alkyl X represents oxygen or sulfur; Me 'represents an alkali metal or an alkaline earth metal; and n represents 1 or 2. 2. - Catalyst according to claim 1, wherein Ar represents phenyl, Cp represents cyclopentadienyl, Flu represents fluorenyl, Me represents zirconium, Q is halogen, R and R 'represent ethyl, X represents oxygen, Me' represents an alkali metal and n represents 2. 3. A catalyst according to Claim 2, wherein Q represents chlorine. 4. A catalyst according to Claim 2, wherein Me 'represents lithium. 5. A process for the preparation of the catalyst according to Claim 1, comprising: (1) Reaction of the substituted or unsubstituted fluorene with a strong base in an ethereal solvent and reaction of the resulting anion of fluorene with a substituted or unsubstituted diarylfulvene on the ring at room temperature to form an ansabicyclopentadienyl derivative ligand (defined as a ligand metallocenyl); (2) reaction of the metallocenyl ligand with an alkaline reagent in an inert solvent, and reaction of the resulting dianion of metallocenyl ligand with a metal compound of the formula MeQ4, in which Me is a metal selected from those of the IVB group of the Periodic Table and 0 is selected from the group consisting of halogen, alkyl, alkoxy, aromatic fused ring group and heterocyclic group. 6. A process according to Claim 5, comprising: (1 Subject the fluorene to the addition reaction with diphenylfulvene in an ethereal solvent in the presence of phenyllithium at room temperature to form the metallocenyl ligand (2) to react the resulting metallocenyl ligand with butyl lithium in diethyl ether and to react the resulting dianion of the ligand metallocenile with 7. A process for the preparation of syndiotactic polyolefin comprising the polymerization of an olefin using the catalyst according to claim 1 as the main catalyst in combination with a cocatalyst selected from the group consisting of methylaluminoxane, a mixture of alkylaluminium and methylaluminoxane, and a compound of organic boron. 8. Process according to Claim 7, wherein said olefin is selected from ethylene and alpha-olefin 9. Process according to Claim 8, wherein said olefin is propylene. 10. Process according to claim 7, wherein the main catalyst is diphenylmethylene chloride (cyclopentadienyl-9-fluorenyl) zirconiumether diethyl-lithium chloride having the following formula: and the cocatalyst is methylaluminooxane.