Pd(I) Dimer Synthesis via Comproportionation for Isomerization

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Solution Overview

Problem

Existing methods for preparing the dimeric Pd(I) bromophosphine complex [Pd(μ-Br)(PtBu3)]2 are inefficient, requiring expensive starting materials, resulting in low yields and significant precious metal losses, making them unsuitable for industrial-scale production and prone to impurities.

Innovation Solution

A new method involving a comproportionation reaction between Pd(II) compound PdBr2 and Pd(0) compound Pd(PtBu3)2, avoiding the use of costly Pd sources with olefinic ligands, allows for high-yield production of [Pd(μ-Br)(PtBu3)]2, with un-reacted PdBr2 being recyclable and the process conducted under mild conditions without the need for an inert gas atmosphere.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If existing methods using Pd-dba complex or Pd-COD compound are employed, then the Pd(I) dimer complex can be prepared, but the yields are low (maximum 60%) and expensive starting materials are required

Engineering Contradiction:

Improveyield of Pd(I) dimer complexVSAvoidcost of starting materials

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent changes the oxidation state parameter of the palladium starting materials from Pd(0) in conventional methods to a mixture of Pd(II) and Pd(0) in the new method. This parameter change enables a comproportionation reaction that produces Pd(I) with yields exceeding 90%, dramatically improving both yield and cost-effectiveness compared to existing methods

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive, air-sensitive Pd-dba and Pd-COD complexes with inexpensive, stable PdBr2 and Pd(PtBu3)2 that can be handled without inert atmosphere. The new starting materials are cheaper, more stable, and eliminate the need for costly protective equipment and procedures

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Loss of substance

If existing synthesis pathways are used, then Pd(I) dimer complex can be obtained, but significant precious metal losses occur and un-reacted educt cannot be easily recovered

Engineering Contradiction:

Improveprecious metal lossVSAvoidease of educt recycling

Core Design Contradiction:

Loss of substanceVSEase of manufacture

Solution Approach 1:

The patent implements a recovery system where un-reacted PdBr2 is filtered off, washed with toluene to remove organic residues, and reused in subsequent reactions. This recovering principle reduces precious metal loss to minimal amounts and makes the manufacturing process economically viable through educt recycling

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The patent extracts and separates un-reacted PdBr2 from the reaction mixture by filtration, removing it as a distinct phase. This extraction allows for easy recovery and reuse of the expensive PdBr2 starting material, minimizing precious metal loss and simplifying the manufacturing process

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If Pd-dba complex or Pd-COD compound is used as starting material, then Pd(I) dimer can be synthesized, but the process requires inert gas atmosphere and complex handling procedures

Engineering Contradiction:

Improvepurity of Pd(I) dimer complexVSAvoidcomplexity of reaction conditions

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent eliminates the requirement for inert gas atmosphere by using starting materials PdBr2 and Pd(PtBu3)2 that are stable in air. This removes the need for complex inert gas handling equipment and procedures, simplifying the manufacturing process while maintaining high product purity

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

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 method provides high yields of [Pd(μ-Br)(PtBu3)]2, enhancing catalytic activity in reactions such as isomerization of allyl esters, and allows for the recycling of PdBr2, making the process economically viable and scalable for industrial use.

Implementation Method 1

A new method involving a comproportionation reaction between Pd(II) compound PdBr2 and Pd(0) compound Pd(PtBu3)2

Methodology Applied

Scientific EffectComproportionation reaction: Redox Reactions

Implementation Method 2

a novel use of the dimeric Pd(l) bromophosphine complex [Pd(μ-Br)(PtBu3)]2 as a catalyst is disclosed

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS9192927B2Method for the preparation of palladium(I) tri-tert-butylphosphine bromide dimer and process for its use in isomerization reactions

Publication Date: 2015.11.24 UMICORE AG & CO KG

AI summary

The invention provides a new method for the preparation of the dimeric Pd(l) tri-tert.-butylphosphine bromide complex, characterized by the chemical formula [Pd(μ-Br)(PtBu3)]2. The method is based on a comproportionation reaction in which a Pd(ll) compound (═PdBr2) is reacted with a Pd(0) compound (═Pd(PtBu3)2) in organic solvents to yield the [Pd(μ-Br)(PtBu3)]2 compound having the Pd atoms in the formal oxidation state +1. Unreacted PdBr2 may be reused in the process. The method is straightforward and applicable for industrial scale production and provides high product yields. Further, a new process for the isomerization of allyl ethers of the general type R1—C(O)—O—CH(R2)—C(R3)═CH2 employing the compound Pdμ-Br)(PtBu3)]2 as a catalyst is disclosed.