Monoisocyanate Conversion to Ureas via Organometallic Catalysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for converting monoisocyanates, such as phenyl isocyanate, into urea compounds are inefficient due to high costs, impurity issues, and the need for additional raw materials, which can lead to contamination and unwanted reactions, making it difficult to recycle and dispose of by-products safely.
Innovation Solution
A method using a non-polar organic solvent and an organometallic catalyst, like bis(cyclopentadienyl) Cr(II), to convert phenyl isocyanate into urea compounds, allowing for their recycling and integration back into polyisocyanate production processes, reducing the need for disposal and minimizing impurity effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water is used to convert monoisocyanate to urea, then the conversion reaction can proceed, but the reaction rate is slow and monoamine by-products are formed causing contamination
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by introducing a base catalyst (metal oxide, hydroxide, or carbinate) to alter the reaction mechanism. This catalytic approach increases the reaction rate significantly compared to uncatalyzed water reaction, while the base catalyst selectively promotes urea formation and suppresses monoamine by-product formation through alternative reaction pathways.
2Productivity
If stoichiometric or greater amounts of polyamines are added to convert monoisocyanate, then conversion can be achieved, but unreacted polyamines remain causing contamination and unwanted reactions
Solution Approach 1:
The patent employs a catalytic amount of base catalyst (metal oxide, hydroxide, or carbinate) that can be easily separated from the reaction mixture and recycled. This catalytic approach eliminates the need to add stoichiometric amounts of polyamines, thereby avoiding contamination from unreacted polyamine while maintaining high conversion efficiency through the catalytic cycle.
3Productivity
If additional raw materials are added to convert monoisocyanate, then conversion can be achieved, but costs increase and additional impurities are introduced
Solution Approach 1:
The patent utilizes water, which is already present in the reaction system or easily available, as the reactant to form urea. The base catalyst (metal oxide, hydroxide, or carbinate) is used in catalytic amounts and can be recovered and reused. This self-service approach eliminates the need to add expensive stoichiometric amounts of polyamines or other raw materials, thereby reducing costs and avoiding introduction of additional impurities while maintaining effective conversion.
4Ease of manufacture
If monoisocyanate is not removed from solvent, then solvent recycling is simplified, but monoisocyanate accumulates over time causing toxicological concerns
Solution Approach 1:
The patent implements a continuous conversion process where monoisocyanate is continuously converted to urea in the solvent stream as it circulates through the reaction system. The base catalyst (metal oxide, hydroxide, or carbinate) facilitates this continuous transformation, preventing accumulation of monoisocyanate over time while allowing the solvent to be continuously recycled without requiring separate removal steps.
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 effectively converts phenyl isocyanate to urea compounds at industrial scales, reducing waste and costs by allowing for the recycling of by-products, thus addressing the inefficiencies and contamination issues of previous methods.
Implementation Method 1
reacting a solution of the organic isocyanate in a liquid nonpolar solvent in the presence of at least 0.025 wt.-% of an organometallic catalyst... to convert at least a portion of the organic isocyanate to the one or more urea compounds
Data Source
AI summary
Organic isocyanates are converted to ureas by heating in the presence of certain cobalt, magnesium, chromium and lanthanide series organometallic catalysts. The process requires no water or other reactants. The process is particularly useful for removing small quantities of monoisocyanates from a solvent stream recovered from a polyisocyanate manufacturing process. The urea compounds in some instances can be recycled back into the polyisocyanate manufacturing process and reacted with polyisocyanate compounds to form biurets.