Polythiol Catalysts for Cis/Trans Isomerization of Unsaturated Compounds
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Solution Overview
Problem
Existing methods for isomerizing unsaturated ketones, ketals, aldehydes, acetals, carboxylic acids, esters, and amides of unsaturated carboxylic acids are inefficient, particularly using organic sulphur compounds which do not effectively isomerize these compounds.
Innovation Solution
A process involving the use of polythiols as catalysts, where a cis or trans isomer of an unsaturated compound is heated with a polythiol at a temperature between 20°C and the boiling point of the compound, leading to efficient cis/trans isomerization, with aromatic polythiols like 4,4'-dimercaptobiphenyl being particularly effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If organic sulphur compounds (monothiols) are used as isomerization catalysts, then the process can be implemented, but the isomerization rate is slow and degradation occurs
Solution Approach 1:
The patent uses polythiols (compounds with multiple thiol groups) instead of monothiols as catalysts. This composite approach with multiple active sites per molecule dramatically increases the isomerization rate while maintaining compound stability, resolving the contradiction between productivity and reliability
Solution Approach 2:
The patent changes the catalyst structure from monothiol to polythiol, increasing the number of thiol groups per molecule. This parameter change in catalyst complexity transforms the reaction kinetics, achieving fast isomerization without degradation
2Productivity
If existing catalysts are used for unsaturated ketones, aldehydes, esters, and amides, then isomerization can occur, but the efficiency is very low
Solution Approach 1:
The patent introduces polythiols as intermediary catalysts that specifically mediate the isomerization of unsaturated ketones, aldehydes, esters, and amides. These polythiol intermediaries provide efficient catalytic pathways that existing catalysts cannot achieve, dramatically improving productivity and reducing reaction time
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 process efficiently transforms undesired isomers into desired isomers, achieving an equilibrium cis/trans ratio, with polythiols showing faster isomerization rates and less degradation compared to monothiols, and can be optimized with the use of polar solvents like DMF and ionic liquids.
Implementation Method 1
adding a polythiol to the cis or trans isomer of the unsaturated compound A of step a); heating the mixture of polythiol and cis or trans isomer of the unsaturated compound A to a temperature of between 20°C and the boiling point of the unsaturated compound A
Data Source
Figure 1a~1b
Figure 2a~3a
Figure 4a~4c
AI summary
The present invention relates to a process of a cis/trans isomerization of an unsaturated compound A being selected from the group consisting of unsaturated ketones, unsaturated ketals, unsaturated aldehydes, unsaturated acetals, unsaturated carboxylic acids, esters of an unsaturated carboxylic acid and amides of an unsaturated carboxylic acid using polythiol as cis/trans isomerization catalyst. It has been observed that the isomerization is very efficient and fast.