Bispyrrolidine Synthesis via Lactone Condensation and Hydrogenation
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Solution Overview
Problem
Current methods for producing bispyrrolidine compounds as catalysts for polyurethane foams involve complex processes and require amine excesses, leading to emissions and inefficiencies, while there is a need for catalysts that minimize emissions without compromising catalytic activity.
Innovation Solution
A two-step process involving the reaction of γ-butyrolactone with diamines to form bisamides, followed by catalytic hydrogenation to produce bispyrrolidine compounds, using a range of catalysts including Raney cobalt and copper-chromium, at controlled temperatures and pressures, without the need for amine excesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods using pyrrolidine and 2-chloroethyl ether or diethylene glycol with Ru catalyst are used, then bispyrrolidine compounds can be produced, but the process becomes complex and requires additional catalyst removal steps
Solution Approach 1:
The invention extracts and eliminates the complex catalyst system from the synthesis pathway. Instead of using Ru catalysts that require removal, the patent employs a direct condensation reaction of γ-butyrolactone with diamines that proceeds without catalyst or with simple acid catalysis, thereby removing the problematic catalyst removal step entirely
Solution Approach 2:
The invention inverts the conventional approach by starting from γ-butyrolactone and diamines rather than from pyrrolidine derivatives. This reverse synthesis strategy simplifies the process by avoiding the need for catalyst-mediated etherification and subsequent catalyst removal, achieving the same bispyrrolidine products through a more direct route
2Productivity
If amine excesses are used in the reaction, then the reaction can proceed, but emissions of amines, DMF and formaldehyde increase
Solution Approach 1:
The invention changes the reaction parameters by using stoichiometric or near-stoichiometric amounts of diamines instead of large excesses. The improved reaction conditions, including controlled temperature and the use of γ-butyrolactone as starting material, allow complete conversion without requiring amine excess, thereby minimizing emissions while maintaining productivity
Solution Approach 2:
The invention converts the potential harm of amine excess into a benefit by designing a reaction system where stoichiometric amounts suffice. The use of γ-butyrolactone and diamines with controlled reaction conditions transforms what would be a harmful waste stream into a efficient, emission-minimal process that maintains high productivity
3Reliability
If current catalyst systems are used, then catalytic activity is achieved, but emissions from degradation products such as amines, DMF and formaldehyde cannot be minimized
Solution Approach 1:
The invention extracts the problematic catalyst system entirely from the process. By using direct condensation of γ-butyrolactone with diamines that proceeds without Ru catalysts or with simple acid catalysis, the patent eliminates the source of degradation products like DMF and formaldehyde, thereby minimizing emissions while maintaining the ability to produce bispyrrolidine compounds with the desired catalytic activity for polyurethane foam production
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 simplifies the production of bispyrrolidine compounds, reduces emissions, and maintains or improves catalytic activity, making it more economical and environmentally friendly.
Implementation Method 1
γ-butyrolactone is reacted with diamines of the formula II to give bisamides of the formula III
Implementation Method 2
the amide function of the bisamides of the formula III subsequently being converted in step II) are partially or completely catalytically hydrogenated to bispyrrolidine compounds of the formula I
Data Source
AI summary
The invention relates to a method for producing compounds of formula (I), in the case of which compounds in a first step γ-butyrolactone is reacted with diamines of formula (II) to form bisamides of formula (III), the amide function of the bisamides of formula (III) subsequently being partially or completely catalytically hydrogenated in step II) to form bispyrrolidine compounds of formula (I).