Indium Catalyst One-Pot Synthesis of Disubstituted Urea and Carbamate
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Solution Overview
Problem
Existing methods for preparing disubstituted urea and carbamate compounds face issues such as the use of toxic reagents, high temperature and pressure requirements, low yields, and unsatisfactory physical properties of polyurethanes derived from aromatic amines, particularly due to the use of phosgene, sulfur, noble metal catalysts, and selenium.
Innovation Solution
A method involving a one-pot reaction of an amine, carbon dioxide, and an alkylene oxide compound using an ionic liquid-based catalyst system containing indium, which allows for the simultaneous preparation of disubstituted urea and carbamate compounds at high yield, avoiding the use of harmful reagents and enabling the use of aliphatic amines to improve polyurethane properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosgene is used to prepare urea from amine, then the reaction proceeds efficiently, but toxic and corrosive phosgene is used and large amount of HCl pollutant is produced
Solution Approach 1:
The patent extracts and eliminates the harmful phosgene reagent from the synthesis pathway, replacing it with carbon dioxide and an alkylene oxide compound. This substitution removes the source of HCl pollution and toxicity while maintaining the ability to produce disubstituted urea compounds through a different chemical route that avoids the problematic byproducts.
Solution Approach 2:
The patent converts carbon dioxide, which is typically considered a waste product or pollutant, into a useful reagent for synthesizing disubstituted urea compounds. By utilizing CO2 as a carbon source in the reaction with amine and alkylene oxide, the process transforms a harmful substance into a beneficial building block, simultaneously reducing greenhouse gas emissions and eliminating the need for toxic phosgene.
2Object-affected harmful factors
If sulfur is used to prepare urea from amine, carbon monoxide and sulfur, then urea can be prepared without phosgene, but byproducts difficult to handle such as H2S are produced
Solution Approach 1:
The patent removes sulfur from the reaction system and replaces it with an alkylene oxide compound. This substitution eliminates the formation of H2S byproduct while maintaining the ability to synthesize disubstituted urea compounds. The alkylene oxide provides the necessary oxygen and carbon atoms without generating harmful sulfur-containing byproducts.
3Manufacturing precision
If noble metal catalysts are used to prepare urea from nitro compound, then conversion rate and selectivity are relatively high, but the expensive noble metal catalyst may be easily decomposed because of high temperature and pressure
Solution Approach 1:
The patent replaces expensive noble metal catalysts with a cheaper indium-based catalyst system. The indium complex provides sufficient catalytic activity for the reaction to proceed with good conversion rate and selectivity, while being more economically viable and potentially more stable under the reaction conditions. This substitution makes the process more suitable for industrial scale-up.
4Productivity
If high temperature and pressure are used to prepare urea from amine and nitrobenzene, then the reaction can proceed, but the maximum yield of urea is low as 73%
Solution Approach 1:
The patent optimizes the reaction parameters including temperature, pressure, and catalyst structure to achieve higher yields. By using an indium-based catalyst with specific ligands and adjusting the reaction conditions, the process achieves over 90% conversion rate and high selectivity for disubstituted urea compounds, significantly improving upon the 73% maximum yield of previous methods.
5Productivity
If selenium catalyst is used to synthesize aliphatic urea from amine, then the reaction can proceed, but a large amount of the catalyst is spent since selenium is used in an equimolar amount with respect to the starting material amine
Solution Approach 1:
The indium-based catalyst system functions as a true catalyst that is not consumed in the reaction, unlike selenium which is used in equimolar amounts. The indium complex can be used in small catalytic quantities and remains active throughout the reaction, enabling the process to proceed efficiently without significant catalyst consumption or the need for frequent catalyst replenishment.
6Productivity
If aromatic amine is used as starting material, then the reaction can proceed under high temperature and pressure, but the physical properties of derived polyurethanes are unsatisfactory due to yellowing
Solution Approach 1:
Instead of using aromatic amines that lead to yellowing polyurethanes, the patent inverts the approach by using aliphatic amines as the starting material. This reversal of the conventional choice of amine type produces polyurethanes with superior physical properties, including better color stability and resistance to yellowing, while the indium catalyst ensures the reaction proceeds efficiently.
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 disubstituted urea and carbamate compounds, improves the physical and chemical properties of polyurethanes, and allows for the reuse of the indium-based catalyst, addressing the limitations of existing methods while reducing environmental impact.
Implementation Method 1
reacting an amine, carbon dioxide and an alkylene oxide compound in the presence of an ionic liquid-based catalyst system containing indium
Data Source
AI summary
The present disclosure relates to a method for preparing a disubstituted urea and carbamate compounds simultaneously through a one-pot reaction of an amine, carbon dioxide and an alkylene oxide compound in the presence of an ionic liquid-based complex catalyst system containing indium. In accordance with the present disclosure, a disubstituted urea and carbamate compounds can be prepared simultaneously at high yield. In addition, the ionic liquid-based catalyst containing indium according to the present disclosure is economical because it can be reused several times.