DOPO Synthesis via One-Pot Acid-Catalyzed Cyclization
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Solution Overview
Problem
Current methods for synthesizing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) are inefficient due to long reaction times, complex processes, environmental pollution, low yields, high energy consumption, and difficulty in controlling purity and color, as they require multiple steps, purification of intermediates, and large quantities of organic solvents.
Innovation Solution
A method involving a single reaction vessel where 6-chloro-6H-dibenz[c,e][1,2]oxaphosphorin is mixed with an acid compound in water to form DOPO, eliminating the need for intermediate isolation and reducing side reactions, with the acid acting as a catalyst to enhance yield and simplify the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional multi-step hydrolytic processes are used to synthesize DOPO, then the reaction can proceed, but the reaction time is too long and productivity is low
Solution Approach 1:
The patent combines multiple reaction steps (hydrolysis, dehydration, and cyclization) into a single integrated reaction process. The chloro-oxaphosphorin compound undergoes hydrolysis with water to form the phosphinic acid intermediate, which then undergoes dehydration and cyclization in the same reaction system to directly produce DOPO, eliminating the need for separate purification and processing steps.
Solution Approach 2:
The reaction system maintains continuous useful action by keeping the phosphinic acid intermediate in the reaction mixture without isolation. The intermediate continuously transforms into the final DOPO product through dehydration and cyclization, maximizing the utilization of reaction time and avoiding idle periods associated with intermediate isolation and purification.
2Manufacturing precision
If traditional methods with multiple purification steps are used, then intermediate products can be isolated, but the process complexity increases and manufacturing costs rise
Solution Approach 1:
The patent extracts and removes the purification steps for intermediate products from the traditional multi-step process. By designing a reaction system where the intermediate phosphinic acid automatically transforms into the final DOPO product, the need for intermediate isolation, purification, and handling is eliminated, significantly simplifying the overall process.
Solution Approach 2:
The reaction system performs self-service by allowing the phosphinic acid intermediate to automatically undergo dehydration and cyclization to form DOPO without requiring external intervention for isolation and purification. The system essentially purifies itself by converting the intermediate directly into the final product through controlled reaction conditions.
3Ease of manufacture
If traditional hydrolytic processes using large quantities of deionized water and organic solvents are used, then hydrolysis can be facilitated, but environmental pollution increases
Solution Approach 1:
The patent changes the reaction parameters by using a minimal amount of deionized water (0.5-2 equivalents) instead of large quantities traditionally used. The reaction is conducted in a solvent-free or reduced-solvent system, and the temperature is optimized (60-100°C) to facilitate hydrolysis and subsequent transformations with minimal water and solvent usage, thereby reducing environmental pollution.
4Manufacturing precision
If traditional methods requiring separation of intermediates are used, then intermediate products can be purified, but the yield is reduced due to losses during separation
Solution Approach 1:
The patent merges the fate of the intermediate phosphinic acid with the final DOPO product by designing a reaction system where the intermediate is not isolated but directly converted to the final product. This eliminates material losses that occur during filtration, transfer, and purification operations, thereby maximizing the overall yield.
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 significantly reduces reaction time, manufacturing costs, and environmental impact by minimizing the use of organic solvents and eliminating the need for intermediate purification, resulting in higher yields and improved purity of DOPO.
Implementation Method 1
Due to the acid compound having a catalytic effect, employing the method to synthesize DOPO or its derivatives can prevent side reactions from occurring and increase yield of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or its derivatives
Implementation Method 2
mixing 6-chloro-6H-dibenz[c,e][1,2]oxaphosphorin or its derivative and an acid compound in water to form an organic layer having 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or its derivative
Implementation Method 3
dehydrating 2-(hydroxy-bipheny1-2-y1)-phosphinic acid to form DOPO at high temperature under vacuum to remove water
Implementation Method 4
dehydrating 2-(hydroxy-bipheny1-2-y1)-phosphinic acid to form DOPO at high temperature under vacuum to remove water
Data Source
AI summary
A method for synthesizing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or its derivatives has a step of introducing 6-chloro-6H-dibenz[c,e][1,2]oxaphosphorin or its derivative, an acid compound and water into a reacting chamber to form an organic layer having 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or its derivative and an aqueous layer. Because the acid compound is from an external source and has a catalyzing effect, employing the method can prevent side reaction from occurring and increase yield of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or its derivative. Furthermore, the method is a one-pot operation of hydrolysis, dehydration and cyclization, so the method does not require purification of intermediates. Therefore, the method is time- and cost-saving and requires less organic solvent, resulting in less pollution to the environment.