Schiff Base Ligand Carbonylation Catalyst for Lactone Yield
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Solution Overview
Problem
Current carbonylation catalysts for producing lactones from epoxides are expensive and have low yields, making them impractical for efficient lactone production.
Innovation Solution
Development of a carbonylation catalyst comprising a metal carbonyl anion ionically bonded to a cation with a ligand featuring 3,5-substituted salicylaldehydes connected by a hydrocarbyl-diimine bridge, which includes a nitrogen atom and is coordinated with a metal, enhancing steric and electronic properties for improved catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Schiff base ligand catalysts are used for carbonylation, then the catalyst can be synthesized, but the yield of lactones is insufficient and the catalyst is not practicable
Solution Approach 1:
The patent modifies the ligand structure by changing parameters such as introducing hydrocarbyl groups at specific positions (3 and/or 5 positions) of the salicylaldehyde residues, adjusting the bridge type (hydrocarbyl-diimine), and modifying the metal center (Al, Cr, Ga, In). These parameter changes optimize the steric and electronic properties of the catalyst, resulting in enhanced catalytic activity and higher lactone yields while maintaining practical effectiveness.
2Productivity
If carbonylation catalysts are developed to improve efficiency, then lactone production yield increases, but the catalyst becomes more complex and harder to synthesize
Solution Approach 1:
The ligand is segmented into distinct functional components: two salicylaldehyde residues connected by a hydrocarbyl-diimine bridge, with specific substitution patterns at the 3 and 5 positions. This segmentation allows each component to contribute specific steric or electronic properties while maintaining an overall manageable structure that can be synthesized from discrete building blocks.
Solution Approach 2:
The patent applies local quality modification by introducing hydrocarbyl groups at specific positions (3 and/or 5 positions) of the salicylaldehyde residues. This localized substitution optimizes the steric environment around the metal center without requiring complete redesign of the entire ligand structure, thus improving catalytic activity while controlling overall complexity.
3Ease of manufacture
If existing catalysts are used for lactone production, then the process can proceed, but the catalyst is expensive and requires additional synthesis steps
Solution Approach 1:
The patent employs preliminary action by pre-assembling the ligand structure with specific hydrocarbyl substitutions and metal coordination before the actual catalytic process. The ligand is designed with built-in steric and electronic features that enhance catalysis, allowing the catalyst to be prepared in fewer steps and at lower cost while maintaining high efficiency.
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 catalyst exhibits high catalytic activity, increased reaction efficiency, reduced side products, extended catalyst longevity, and easier recovery, leading to higher yields of lactones from epoxides and carbon monoxide.
Implementation Method 1
a metal carbonyl anion and a cation ionically bonded to the metal carbonyl anion
Implementation Method 2
a metal coordinated with the ligand at each hydroxyl residue and the two residues of the 3,5-substituted salicylaldehydes at a 2 position and at each of the nitrogen atoms of the hydrocarbyl-diimine bridge
Implementation Method 3
contacting an epoxide and carbon monoxide in the presence of a composition that is a carbonylation catalyst to form beta propiolactone
Data Source
AI summary
A composition, comprising: a metal carbonyl anion; and a cation ionically bonded to the metal carbonyl anion. The cation includes a ligand and a metal centered compound. The ligand includes two residues of 3,5-substituted salicylaldehydes connected by an hydrocarbyl-diimine bridge that includes a nitrogen atom contacted with a carbon of an aldehyde residue at each of the two residues of the 3,5-substituted salicylaldehydes. Each of the residues of the 3,5-substituted salicylaldehydes are independently substituted at one or both of a 3 position and a 5 position by a hydrocarbyl group containing at least 5 carbons. The metal coordinated with the ligand at each hydroxyl residue the two residues of the 3,5-substituted salicylaldehydes at a 2 position and at each of the nitrogen atoms of the hydrocarbyl-diimine bridge. The composition includes two polar ligands coordinated with the metal.