Ruthenium Complex Preparation via Inert Solvent
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Solution Overview
Problem
Current methods for preparing the cis-form of ruthenium(II) complexes as hydrogenation catalysts are inefficient due to high reaction temperatures, expensive catalyst precursors, long reaction times, and generation of toxic byproducts and phosphorous waste, making them unsuitable for industrial-scale production.
Innovation Solution
A process involving the reaction of RuCl2 complexes with bidentate amine and phosphine ligands in specific inert solvents at elevated temperatures, allowing for the selective formation of the cis-complex with reduced reaction times and minimized waste, using precursors like cis,cis-cycloocta-1,5 diene or dimethylsulfoxide, and employing a one-pot procedure for efficient catalyst production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the Carpenter procedure is used to prepare ruthenium complexes, then the reaction can proceed at lower temperatures, but the catalyst precursor is highly expensive and not available on an industrial scale
Solution Approach 1:
The patent replaces the expensive and industrially unavailable Carpenter catalyst precursor with inexpensive, readily available alternatives such as RuCl2(PPh3)3, RuCl2(COD), or RuCl2(NBD). These cheaper precursors achieve the same catalytic function without the cost and availability constraints of the original precursor.
Solution Approach 2:
The patent modifies the reaction conditions by changing the solvent system and adding specific additives (acetonitrile, water, or alcohols) to enable the use of alternative precursors. This parameter change allows the reaction to proceed with inexpensive precursors while maintaining effectiveness.
2Temperature
If the Carpenter procedure is used to prepare ruthenium complexes, then the reaction can proceed at lower temperatures, but two equivalents of toxic pyridine are generated
Solution Approach 1:
The patent converts the harmful pyridine byproduct issue into a benefit by designing a procedure where no toxic pyridine is generated. The alternative precursor approach eliminates the formation of toxic byproducts entirely, turning a harmful process into a clean, environmentally friendly one.
Solution Approach 2:
The patent extracts and removes the source of toxic pyridine generation from the reaction system by avoiding the Carpenter precursor entirely. The alternative precursors and modified conditions prevent the formation of harmful byproducts from the start.
3Manufacturing precision
If the WO 2005/105819 procedure is used to prepare the cis-form of ruthenium complexes, then long reaction times (20 hours) are required, but the procedure uses expensive triphenlyphosphine-based catalyst precursors
Solution Approach 1:
The patent changes the solvent parameters (using toluene or xylene with specific boiling points) and adds small amounts of water or alcohols to enable faster reaction times (3-6 hours instead of 20 hours) while maintaining high selectivity for the cis-form product.
Solution Approach 2:
The patent introduces water or alcohol as an intermediary substance that facilitates the ligand exchange reaction, enabling it to proceed faster while still achieving the desired cis-form selectivity. This intermediary mediates between the precursor and ligands to accelerate the process.
4Manufacturing precision
If the WO 2005/105819 procedure is used to prepare the cis-form of ruthenium complexes, then long reaction times (20 hours) are required, but three equivalents of phosphorous waste are generated per equivalent of catalyst
Solution Approach 1:
The patent extracts and eliminates the source of phosphorous waste by using precursors that require minimal or no phosphine ligand exchange. The RuCl2(COD) and RuCl2(NBD) precursors can proceed with very low phosphine equivalents (0.1-1.0 eq), dramatically reducing phosphorous waste generation.
Solution Approach 2:
The patent changes the stoichiometric parameters of phosphine ligand usage from at least 3 equivalents (in WO 2005/105819) to only 0.1-1.0 equivalents, reducing phosphorous waste by a factor of 3-30 times while maintaining catalytic effectiveness.
5Manufacturing precision
If high reaction temperatures are used to form the cis-complex, then the highly active cis-complexes can be formed, but the solvent must have sufficiently high boiling point
Solution Approach 1:
The patent selects solvents with specific boiling point parameters (toluene: 110°C, xylene: 138°C) that are high enough to enable cis-complex formation but manageable for industrial processing. The addition of small amounts of water or alcohol further modifies the reaction parameters to facilitate cis-form formation at these temperatures.
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
This method achieves high yields of the cis-complex with rapid crystallization and filtration, significantly reducing phosphane waste and reaction times, enabling economically advantageous and environmentally friendly large-scale production of highly active ruthenium catalysts for hydrogenation reactions.
Implementation Method 1
the cis-form of certain ruthenium(II) complexes, for example RuCl2[PPh2(CH2)4PPh2][2-(H2NCH2)C5H4N] of formula Ia are useful as a highly active hydrogenation catalysts
Implementation Method 2
in the oxidative synthesis of amides or esters
Data Source
AI summary
The present invention relates to a process for the preparation of a compound of formula (I), wherein X is -CH2-, -CH2-CH2-, -CH2-CH2-CH2- or -CH2-CH2-CH2-CH2-; Y1 is -CH2-; -CH2-CH2- or -NH-; Y2 is NHR7 or SH; wherein R7 is hydrogen, C1-C4alkyl or phenyl; R-1 and R2, independently from each other, represent aliphatic or aromatic groups; R3 and R4, independently from each other, represent aliphatic or aromatic groups; R5 and R6 are each hydrogen or represent together with the carbon atoms to which they are bonded, a phenyl ring; which process comprises reacting a compound of formula II [RuCI2(R8)n]m (II), wherein n is 1 and m is > 1 which represents a polymeric structure if R8 is a molecule containing two alkene or alkyne moieties coordinating in an hapto-2 coordination mode to the metal; or n is 4 and m is 1 if R8 is a nitrogen, oxygen or sulfur containing molecule in which said nitrogen, oxygen or sulfur coordinate to the metal; in the presence of an inert solvent which boiling point is from 1 12°C to 165°C with a compound of formula (III), wherein R5, R6, Y1 and Y2 are as defined under formula I, and a phosphane of formula IV R3R4P-X-PR1 R2 (iv), wherein R1, R2, R3, R4 and X are as defined under formula I.