Continuous Acid Feeding for Stable Dianhydride Dehydration
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Solution Overview
Problem
The existing method for producing 1,2,4,5-cyclohexanetetracarboxylic dianhydride using acetic anhydride as a dehydrating agent is inconsistent in achieving high dehydration rates due to varying conditions.
Innovation Solution
Feeding 1,2,4,5-cyclohexanetetracarboxylic acid in a continuous manner to acetic anhydride in a slurry state with acetic acid as the solvent, maintaining an average particle size of the acid below 20 µm and a reaction temperature between 80°C to 150°C, stabilizes the dehydration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a method involving thermal reflux using acetic anhydride is used to cyclodehydrate 1,2,4,5-cyclohexanetetracarboxylic acid, then dehydration can be achieved, but the dehydration rate cannot be stably reproduced depending on the conditions
Solution Approach 1:
The patent applies parameter changes by controlling the particle size of 1,2,4,5-cyclohexanetetracarboxylic acid to less than 20 μm and maintaining specific molar ratios of acetic anhydride (2.0 to 100 moles per mole of acid). These parameter controls stabilize the dehydration rate and make the process reliably reproducible across different conditions while maintaining high productivity.
2Reliability
If the particle size of 1,2,4,5-cyclohexanetetracarboxylic acid is reduced to less than 20 μm and fed continuously to acetic anhydride, then the dehydration rate becomes stable and high, but the process complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-grinding the 1,2,4,5-cyclohowanetetracarboxylic acid to achieve the required particle size of less than 20 μm before the dehydration reaction. This preliminary size reduction enables stable and high dehydration rates during the reaction while keeping the actual dehydration process simple and straightforward.
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 consistently achieves a high dehydration rate, ensuring the production of 1,2,4,5-cyclohexanetetracarboxylic dianhydride with excellent purity and stability.
Implementation Method 1
1,2,4,5-cyclohowanetetracarboxylic acid is subjected to a dehydration reaction in a slurry state in the presence of a dehydrating agent, wherein the dehydrating agent is acetic anhydride
Implementation Method 2
the dehydration reaction of the 1,2,4,5-cyclohowanetetracarboxylic acid is carried out in the presence of the dehydrating agent and a solvent, wherein the solvent is acetic acid
Data Source
AI summary
An object of the present invention is to provide a method for producing 1,2,4,5-cyclohexanetetracarboxylic dianhydride, which is capable of stably achieving a high dehydration rate. The method for producing 1,2,4,5-cyclohexanetetracarboxylic dianhydride of the present invention is a method for producing 1,2,4,5-cyclohexanetetracarboxylic dianhydride by subjecting 1,2,4,5-cyclohexanetetracarboxylic acid to a dehydration reaction in a slurry state in the presence of a dehydrating agent, wherein the 1,2,4,5-cyclohexanetetracarboxylic acid is fed in a divided or continuous manner to the dehydrating agent.