NL9400919A - Novel organometallic compounds and method for polymerizing alkenes with the use of these organometallic compounds as catalysts - Google Patents

Abstract

Compounds according to the formula (1), where Q represents -N-Si(CH3)3 or -C(H)-Si(CH3)3; R represents an alkylene group or an o-arylene group; R' represents a t-butyl group or a t-pentyl group; M represents Zr, Ti or Hf; A represents an easily detachable group, preferably compounds in which Q represents -N-Si(CH3)3; R represents an ethylene group or an o-phenylene group which may or may not be substituted; R' represents a t-butyl group; M represents Zr; A represents a halogen atom.

Description

NEW ORGANOMETAL COMPOUNDS AND METHOD FOR POLYMERIZING OLEFINS USING THESE ORGANOMETAL COMPOUNDS AS CATALYSTS.

The invention provides organo-oral compounds of the formula (1), wherein Q represents -N-Si (CH 3) 3 or -C (H) -Si (CH 3) 3; R represents an alkylene group or an arylene group; R 'represents a t-butyl group or a t-pentyl group; M represents Zr, Ti or Hf; and A represents a group that can be easily split off.

Preferably Q is -N-Si (CH 3) 3; R is an ethylene group or an unsubstituted or substituted o-phenylene group, wherein the optional substituent on the o-phenylene group is preferably in position 3 or position 4; R 'a t-butyl group; M Zr; and A is a halogen atom.

In particular, the invention provides a compound of the formula (2), the molecular formula of which is ZrHNfRJCiBu ^ CH ^ Cg ^ - 1,2] Cl2. (Bufctert.butyl)

The above compounds are suitable as catalysts for the polymerization (both homo- and copolymerization) of olefins, for example ethylene or propylene.

Numerous catalysts exist for the polymerization of olefins. An important group is formed by the metallocenes, such as those mentioned in Chemistry in Britain, February 1994, namely Cp2ZrCl2 (in which Cp * cyclopentadienyl) and those according to formulas (3), (4) and (5). The metallocenes have numerous advantages: they can be used to control stereoregularity and molecular weight distribution to obtain polymers "tailored" for certain applications, and they are soluble in hydrocarbons to form homogeneous catalytic systems.

The present new cyclopentadienyl-free polymerization catalysts have a useful and distinctive catalytic activity and can be prepared in a very simple manner.

Preparation of the Zr compound according to formula 12}.

The starting material for this synthesis was Li2 (TMEDA) 2 {1,2-C6H4 (CHSi (CH3) 3) 2>, in which TMEDA-tetramethyl ethylene diamine, Me2NCH2CH2NMe2. This compound was prepared as described in an article by M.F. Lappert et al., Inorg. Syth., 1989, 26, 144. This compound was reacted with BufcCN to give [Li2 (TMEDA) 2 {1,2-C6H4 (CHCButNSi (CH3) 3) 2>], the latter compound being reacted with potassium t-butoxide to the corresponding potassium derivative; reaction of the potassium compound with ZrCl4 gave the compound of the formula (2), Zr [{N (Si (CH3) 3) C (But) CH} 2C6H4-1,2] Cl2.

Preparation of Li2 (TMEDA) 2 ^ o »C £ H1CHCButNSi (CH3) 3>

ButCN (1.39ml, 12.6mmol) was added dropwise to a solution of (Li2 (TMEDA) 2 {1,2-C6H4 (CHSi (CH3) 3) 2}] (3.1g, 6.28mmol) in Et 2 O (about 40 ml) at about 25 ° C with stirring The resulting orange solution was stirred for 12 hours Volatiles were removed at 90 ° C / 10-2 Torr and the residue was taken up in hexane (about 50 ml) The filtered extract was concentrated to give yellow crystals of the title compound (3.1 g, 75%).

Preparation of K2 (TMEDA) 211.2-C6H4 (CHCBu ^ Si (

Hexane (about 30 ml) was added to a mixture of the above-obtained lithium compound (1.86 g, 2.82 mmol) and KOBu * (0.80 g, 6.55 mmol) at 25 ° C with stirring. The mixture was heated at 60 ° C for half an hour and then stirred at 25 ° C for 12 hours, resulting in the formation of a bright yellow precipitate, which was filtered off and dried in vacuo. The residue was the desired potassium compound (1.60 g, 93%).

Preparation of SiNFSifCH2 ^ CiBu ^ CHKCeHj-1 ^ Cl2.

Zirconium (IV) chloride (0.37g, 1.59mmol) was added to a solution of the potassium compound prepared above (0.86g, 1.42mmol) in toluene with stirring and cooling (-78 ° C) ( about 25 ml). The mixture was warmed slowly to room temperature, heated to 70 ° C for 2 hours and stirred for an additional 12 hours. The white precipitate obtained was filtered off. Concentration of the filtrate gave light yellow crystals of the final zirconium compound Ζγ {Ν (Κ) 0 (Β ^) 0Η> 206Η4-1.2) 012 (0.76 g, 93%). The molecular structure was evident from the X-ray diffraction pattern of a single crystal, see Table 1 below and structural formula (6).

Table 1. Intramolecular distances (A) and angles (°); Estimated standard deviations in parentheses.

Ethylene was polymerized using the zirconium compound prepared above in an amount of 15 mg and methylaluminoxane (MAO) as a co-catalyst in an amount of 400 mg. The reaction was started at room temperature and the maximum temperature caused by the exothermic reaction was 70 ° C. An experiment was also conducted with ZrCp2Cl2 as a comparative catalyst. The test conditions and results are shown in Table 2 below.

Table 2

the amount of Al is optimized.

Both runs lasted 1 hour and were started at room temperature.

The above table shows that a better polymer result was obtained with the catalyst according to formula (2) according to the invention than with the comparative catalyst [ZrCp2Cl2].

Claims (8)

Compounds of formula (1), wherein Q represents -N-Si (CH 3) 3 or -C (H) -Si (CH 3) 3; R represents an alkylene group or an o-arylene group; R 'represents a t-butyl group or a t-pentyl group; M represents Zr, Ti or Hf; A represents a group that can be easily split off. A compound according to claim 1, wherein Q represents -N-Si (CH 3) 3; R represents an ethylene group or an unsubstituted or substituted o-phenylene group; R 'represents a t-butyl group; M represents Zr; A represents a halogen atom. A compound of the formula (2), wherein Bufc represents a tertiary butyl group. 4. Process for the homo- or copolymerization of olefins, characterized in that a compound according to any one of claims 1-3 is used as a catalyst. 5. Process according to claim 4, characterized in that a co-catalyst is also used. Process according to claim 5, characterized in that the cocatalyst is a methylaluminoxane. Process according to claim 4, 5 or 6, characterized in that ethylene or propylene is subjected to homopolymerization. 8. Process for preparing the compound of formula (2), wherein Li2 (tetramethylethylene diamine) 2 {1,2-C6H4 (CHSi (CH3) 3) 2} is reacted with BufcCN to give Li2 (tetramethyl ethylene diamine) 2 {1 .2-C6H4 (CHCButNSi (CH3) 3) 2) / the latter compound reacts with potassium t-butylate to form K2 (tetramethylethylenediamine) {1,2-C6H4 (CHCB ^ NSi (CH3) 3) 2} and the resulting reacts the compound with ZrCl4 to form the compound of the formula (2).