Volatile Acid Catalyst Transanhydrization for Acrylic Anhydride
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Solution Overview
Problem
Conventional processes for preparing (meth)acrylic anhydride involve cumbersome post-treatment steps for catalyst elimination and can result in the formation of by-products, which are difficult to manage, especially in batch processes, and often lead to reduced yield.
Innovation Solution
A process using a more volatile acid catalyst, such as triflic acid, in a transanhydrification reaction where the catalyst and by-products are easily separable by evaporation, allowing for continuous operation and minimizing post-treatment complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If homogeneous catalysts such as sulfuric acid or sulfonic acids are used to improve the reaction, then the reaction efficiency is improved, but cumbersome post-treatment steps are required to separate the catalyst from the anhydride
Solution Approach 1:
The patent changes the physical parameter of the catalyst from non-volatile to volatile by selecting trifluoroacetic acid, triflimide, or triflic acid. These catalysts have sufficiently high volatility to be easily separated from the (meth)acrylic anhydride product through simple evaporation or distillation, eliminating the need for complex post-treatment steps while maintaining high catalytic activity
Solution Approach 2:
The patent extracts the catalyst from the final product mixture by exploiting the volatility difference between the volatile acid catalyst and the less volatile (meth)acrylic anhydride. This allows the catalyst to be easily removed through evaporation or distillation, simplifying the purification process
2Ease of manufacture
If batch type processes are used for synthesis, then the process is easier to implement, but by-products continue to be formed and yield is reduced
Solution Approach 1:
The patent implements continuous or semi-continuous transanhydrification processes where (meth)acrylic acid reacts continuously with acetic anhydride in the presence of the volatile acid catalyst. This continuous operation allows for better control of reaction conditions, reduced by-product formation, and improved yield compared to batch processes, while the volatile catalyst enables easy removal without complicating the continuous operation
3Productivity
If conventional transanhydrification with acetic anhydride is used, then the desired anhydride is formed, but by-products such as polymerization products and addition products are formed requiring purification
Solution Approach 1:
The patent employs continuous transanhydrification processes that maintain optimal reaction conditions throughout the reaction, minimizing the time available for side reactions such as polymerization and addition. The continuous removal of acetic acid by distillation also shifts the equilibrium toward the desired anhydride product
Solution Approach 2:
The patent uses volatile acid catalysts that operate at lower concentrations and temperatures compared to conventional methods, reducing the rate of by-product formation while maintaining high selectivity for the desired anhydride product
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 approach enables efficient isolation and purification of (meth)acrylic anhydride with high yield, reducing by-product formation and simplifying the process by facilitating easy separation of the catalyst and anhydride, thus improving the overall efficiency and yield of the reaction.
Implementation Method 1
the presence of an acid catalyst more volatile than said anhydride A-C(=O)-O-(O=)C-A, and chosen from trifluoroacetic acid, triflimide and triflic acid
Implementation Method 2
the catalyst and by-products are easily separable by evaporation
Implementation Method 3
The acetic acid formed is generally removed by distillation as it forms
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a process for preparing an anhydride of formula A-C(=O)-O-(O=)C-A, where A is -CR=CH2 and R is -H or -CH3, comprising: a) a step of reacting an anhydride B-C(=O)-O-(O=)C-B with an acid A-COOH, A being as defined above, wherein the step results in the formation of an anhydride A-C(=O)-O-(O=)C-B and of an acid B-COOH, A and B being such that said acid B-COOH is more volatile than said acid A-COOH, and b) a step of reacting said anhydride A-C(=O)-O-(O=)C-B with the acid A-COOH under conditions such that the amount of acid B-COOH is less than the amount of acid A-COOH, resulting in the formation of the anhydride A-C(=O)-O-(O=)C-A, in which said reaction steps are carried out in the presence of an acid catalyst which is more volatile than said anhydride A-C(=O)-O-(O=)C-A.