Lanthanide Borohydride Metallocene for 1,2-Cyclohexane Links

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Solution Overview

Problem

Current catalytic systems based on halogenated metallocene complexes of lanthanides are ineffective for the copolymerization of olefins and conjugated dienes, particularly in producing copolymers with 1,2-cyclohexane links, which are essential for specific polymer properties.

Innovation Solution

A borohydride metallocene complex of a lanthanide, specifically formulated as [Me2SiFlu2Nd(BH4)2Li(THF)]2, is used in combination with an alkylation cocatalyst to achieve high catalytic activity for copolymerizing ethylene and butadiene, resulting in copolymers with a high molar level of 1,2-cyclohexane links.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If halogenated metallocene complexes of lanthanides are used for copolymerization, then the catalytic system is established, but the catalytic activity is insufficient and 1,2-cyclohexane links cannot be produced

Engineering Contradiction:

Improvecatalytic activityVSAvoideffectiveness for producing 1,2-cyclohexane links

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the metallocene complex by replacing halogenated ligands with borohydride ligands (BH4-) and introducing specific alkyl groups (iPr, nPr) on the cyclopentadienyl rings. This parameter change transforms the catalytic properties, enabling both high activity and the specific ability to produce 1,2-cyclohexane links that halogenated complexes cannot achieve

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite catalytic system by combining the borohydride metallocene complex with specific cocatalysts (alkylmagnesium, alkyllithium, alkylaluminium, or Grignard reagents). This composite approach synergistically enhances catalytic activity while enabling the formation of 1,2-cyclohexane links through the coordinated action of the complex and cocatalyst

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If conventional metallocene complexes are used, then the copolymerization process can be initiated, but the molar level of 1,2-cyclohexane links remains below 20%

Engineering Contradiction:

Improvemolar level of 1,2-cyclohexane linksVSAvoidcatalytic activity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The invention introduces specific local structural features - isopropyl (iPr) and n-propyl (nPr) groups at specific positions on the cyclopentadienyl rings. These localized structural modifications create a specific steric and electronic environment at the catalytic center that favors the formation of 1,2-cyclohexane links, achieving over 20% molar level of this specific microstructure

Inventive Principle:

Principle #3Local quality

3Strength

If halogenated metallocene complexes are used, then the copolymerization can proceed, but the molecular weight and polydispersity indices are not optimized

Engineering Contradiction:

Improvemolecular weightVSAvoidpolydispersity control

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The invention employs a feedback mechanism through the specific borohydride metallocene complex structure that regulates the catalytic cycle. The borohydride ligand and propyl-substituted cyclopentadienyl groups create a controlled steric environment that provides feedback control over chain growth, resulting in optimized molecular weights and narrowed polydispersity indices compared to halogenated complexes

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The borohydride metallocene complex significantly enhances catalytic activity, producing ethylene/butadiene copolymers with over 25% butadiene units and greater than 20% 1,2-cyclohexane links, offering improved molecular weights and polydispersity indices, thus overcoming the limitations of previous systems.

Implementation Method 1

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS8268949B2Borohydride metallocene complex of a lanthanide, catalytic system including the said complex, polymerisation method using same and ethylene/butadiene copolymer obtained using said method

Publication Date: 2012.09.18 TOTAL PETROCHEMICALS FRANCE

AI summary

Borohydride metallocene complex of lanthanide, preparation process, catalytic system incorporating it, copolymerization of olefins employing catalytic system and ethylene/butadiene copolymer, the butadiene units comprise 1,2-cyclohexane or 1,2- and 1,4-cyclohexane links. The complex corresponds to of formulae A and/or B:where, in A two ligands Cp1 and Cp2, each of a fluorenyl group, are connected to the lanthanide Ln, where, in B, a ligand molecule, composed of two fluorenyl groups Cp1 and Cp2 are connected via bridge P of formula MR1R2, is an element from group IVa, R1 and R2, which are identical or different, represent an alkyl group comprising from 1 to 20 carbon atoms, connected to lanthanide Ln, L is alkali metal, N is molecule of a complexing solvent, x is integral or non-integral number ≧0 and p is integer ≧1.