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Catalysts for olefin polymerization

Inactive Publication Date: 2011-12-15
EQUSR CHEM LP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006]The invention relates to catalysts useful for polymerizing olefins. The catalysts comprise an activator and a bridged cyclopentadienyl complex that incorporates a monoanionic hydroxylamido (NO) or hydrazido (NN) ligand fragment. Using a modeling a

Problems solved by technology

In particular, changing from tetramethylcyclo-pentadienyl to the more readily available Cp or indenyl ligand generally hurts both productivity and the ability to incorporate comonomers.
Changing the bridging group from the usual single-atom bridge (e.g., a divalent methylene or dimethylsilylene group) to even a simple two-carbon bridge (ethylene) has also proved unfavorable.
The need to synthesize the bridged Cp* ligand makes this approach challenging from an industrial perspective.
Because of the relatively poor track record of Cp complexes currently available, however, it remains a challenge to identify viable complexes of this type.

Method used

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  • Catalysts for olefin polymerization
  • Catalysts for olefin polymerization
  • Catalysts for olefin polymerization

Examples

Experimental program
Comparison scheme
Effect test

example 34

Synthesis of Complex 1

[0028]

[0029]Following the method of Bernardi et al. (J. Org. Chem. 64 (1999) 641, N-methylhydroxylamine hydrochloride is combined with 1.1 eq. of 2,4,6-trimethylpyridine in pentane at room temperature for 12 h, followed by treatment with 1 eq. of 1-(trimethylsilyl)imidazole with stirring for 9 h. Filtration, concentration, and distillation should provide N-methyl-O-(trimethylsilyl)hydroxylamine.

[0030]n-Butyllithium (1.1 eq.) is added to N-methyl-O-(trimethylsilyl)hydroxylamine in THF at −78° C. to generate the corresponding amido anion. Dimethylfulvene (1 eq.) is slowly added at −78° C. The stirred mixture is allowed to warm to room temperature for 2 h, and it is then re-cooled to −78° C. Titanium tetrachloride (1 eq.) in dry toluene is slowly added to the cyclopentadienyl anion, and the mixture is warmed to room temperature and stirred overnight. The mixture is refluxed to eliminate trimethylsilyl chloride. After extractive workup, the titanium complex is isol...

example 35

Synthesis of Complex 4

[0031]

[0032]Dichlorodimethylsilane is reacted with one equivalent of sodium cyclopentadienide in ether to give (Cp)Me2SiCl. Separately, n-butyllithium (1.1 eq.) is added to N-methyl-O-(trimethylsilyl)hydroxylamine (prepared as described in Example 34) in THF at −78° C. to generate the corresponding amido anion. The amido anion and an equivalent of the silyl chloride are combined at −78° C., followed by stirring the mixture at room temperature overnight. This should provide, after workup, the desired ligand precursor, (Cp)Me2SiNMe-OTMS.

[0033]Deprotonation with n-butyllithium to give a cyclopentadienide, followed by reaction in toluene with titanium tetrachloride and refluxing should eliminate chlorotrimethylsilane and give a titanium dichloride complex, which can be reacted with two equivalents of methyllithium to give 4.

example 36

Synthesis of Complex 5

[0034]

[0035]N,N′-dimethylhydrazine is converted to its monolithium salt by reaction with 1.1 eq. of n-butyllithium in THF at −78° C. The mixture warms to room temperature for 2 h, and is then chilled to −78° C. The mixture is combined with one eq. of CpMe2SiCl at −78° C. and stirred overnight at room temperature. After workup, the expected product is the desired ligand precursor, (Cp)Me2-SiN(Me)-N(Me)TMS. Repeating the remaining steps as in Example 35 should provide complex 5.

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Abstract

Catalysts useful for polymerizing olefins are disclosed. The catalysts comprise an activator and a bridged cyclopentadienyl complex that incorporates a monoanionic hydroxylamido or hydrazido ligand fragment. Suitable complexes have the structure:wherein M is a Group 4 metal; Z is a divalent linking group; X is N or O; each of R1 and R2 is independently C1-C4 alkyl or C6-C10 aryl; R1 and R2 can be joined together; n is 0 when X is O, and n is 1 when X is N; each Y is independently halide, alkyl, dialkylamido, aryl, or aralkyl. A modeling approach is used to identify particular valuable complexes, each of which incorporates a readily synthesized cyclopentadienyl precursor.

Description

FIELD OF THE INVENTION[0001]The invention relates to catalysts useful for polymerizing olefins. The catalysts comprise a complex that incorporates a monoanionic hydroxylamido or hydrazido ligand fragment.BACKGROUND OF THE INVENTION[0002]The modern era of polyolefin catalysis has been dominated by a shift toward single-site catalysts, particularly metallocenes, and their ability to make polymers with differential, tailored properties. “Constrained geometry” complexes are one class of such single-site catalysts (see, e.g., U.S. Pat. No. 5,064,802). The complexes feature a cyclopentadienyl (“Cp”) or Cp-like ligand that coordinates to the transition metal (typically a Group 4 metal) in η5 fashion. The Cp ligand is bridged, usually to an anionic amido group that also bonds to the metal. Upon activation, the cationic center is highly exposed, which contributes to good activity and enables excellent incorporation of α-olefin comonomers (1-butene, 1-hexene, etc.) into the growing polymer ch...

Claims

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Application Information

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IPC IPC(8): C08F4/76B01J31/18C08F4/602B01J31/12
CPCC08F10/00C08F2420/02C08F4/6592Y10S526/943
Inventor NAGY, SANDORCHEVALIER, REYNALD
Owner EQUSR CHEM LP
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