Aromatic Dianhydride Isolation via Segmented Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing aromatic dianhydrides result in decreased yields due to by-product formation, necessitating an improved method for high-yield production with minimized by-product formation.
Innovation Solution
A method involving reacting an aromatic diimide with a substituted or unsubstituted phthalic anhydride in an aqueous medium with a (C1-20) alkyl-substituted amine exchange catalyst at specific temperature and pressure conditions, followed by extraction with organic solvents at distinct temperatures to isolate aromatic dianhydride with reduced imide anhydride content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional exchange reaction methods are used to produce aromatic dianhydrides, then the reaction can be carried out, but by-product formation increases and yield decreases
Solution Approach 1:
The extraction process is divided into multiple stages with different temperatures and solvent ratios to selectively remove different by-products at different stages, thereby increasing dianhydride yield while minimizing by-product formation
Solution Approach 2:
The patent employs multiple extraction temperatures (first extraction at lower temperature, second extraction at higher temperature) and varies organic solvent to aqueous medium ratios to optimize the removal of different by-products, thereby improving dianhydride yield
2Object-generated harmful factors
If extraction is performed at high temperature to remove by-products, then by-product removal improves, but dianhydride decomposition may occur
Solution Approach 1:
The extraction process is segmented into two distinct temperature stages: first extraction at lower temperature (60-160°C) to remove sensitive by-products, and second extraction at higher temperature (160-250°C) to remove more stable by-products, thereby preventing dianhydride decomposition while maximizing by-product removal
Solution Approach 2:
The first extraction at lower temperature serves as a preliminary step to remove the most sensitive by-products before the second extraction at higher temperature, preventing dianhydride decomposition while still achieving effective by-product removal
3Manufacturing precision
If multiple extractions are performed to increase purity, then by-product removal improves, but process complexity and time increase
Solution Approach 1:
The extraction process is divided into two distinct stages with different temperatures and solvent ratios, allowing selective removal of different by-products. This segmented approach achieves high purity (imide anhydride content of 2 weight percent or less) while avoiding the excessive complexity of multiple sequential extractions
4Productivity
If high solids content is used in the reaction mixture, then extraction efficiency improves, but heat transfer and mixing become more difficult
Solution Approach 1:
The patent specifies a solids content range of 16.5-24 wt% and adjusts extraction temperatures and solvent ratios accordingly. This parameter optimization maintains adequate heat transfer and mixing while achieving high extraction efficiency and dianhydride conversion
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 increases overall dianhydride conversion and yield, reducing imide anhydride by-products, which facilitates the production of high molecular weight poly(etherimide) with improved purity.
Implementation Method 1
reacting an aromatic dianhydride and an organic diamine in an inert solvent at elevated temperatures to form an amide-acid polymer via ring opening of the anhydride by nucleophilic attack of the diamine
Implementation Method 2
removing the N-substituted phthalimide from the aqueous reaction mixture by extracting the aqueous reaction mixture with an organic solvent in a first extractor
Data Source
Figure 1~2
Figure 3
AI summary
A method for producing an aromatic dianhydride includes reacting an aromatic diimide with a substituted or unsubstituted phthalic anhydride in an aqueous medium in the presence of an amine exchange catalyst to provide an aqueous reaction mixture including an N-substituted phthalimide, an aromatic tetraacid salt, and at least one of an aromatic triacid salt and an aromatic imide diacid salt. The method further includes removing the phthalimide from the aqueous reaction mixture by extracting the aqueous reaction mixture with an organic solvent in a first extractor for a first time period, at a first extraction temperature and subsequent to the first time period, extracting the aqueous reaction mixture with an organic solvent in a second extractor for a second time period, at a second extraction temperature. The aromatic tetraacid salt is converted to the corresponding aromatic dianhydride. Aromatic dianhydrides prepared according to the method are also described.