Activated Polyethylene Glycol Purification via pH-Driven Phase Separation
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Solution Overview
Problem
Current methods for producing activated polyethylene glycol compounds are not suitable for large-scale industrial production due to high solvent usage and low yield, and existing purification techniques result in products with residual 4-nitrophenol impurities, leading to coloration and inefficient removal processes.
Innovation Solution
A method involving the reaction of polyethylene glycol with an amine compound in an aprotic solvent, followed by the addition of a basic aqueous solution to create a two-phase mixture, allowing for the separation of activated polyethylene glycol and 4-nitrophenol, thereby achieving high-purity and high-yield production without the need for large amounts of adsorbents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If purification is performed using adsorption with resin, then 4-nitrophenol can be removed, but the product turns pale yellow and a large amount of adsorbent waste is generated
Solution Approach 1:
The patent changes the pH parameter of the aqueous solution to 10 or higher, which causes 4-nitrophenol to exist in its ionized form (4-nitrophenolate). This parameter change enables selective partitioning where the ionized 4-nitrophenol remains in the aqueous phase while the activated polyethylene glycol stays in the organic phase, achieving purification without adsorbent waste
Solution Approach 2:
The patent extracts 4-nitrophenol from the reaction mixture by adding a basic aqueous solution to create a two-phase system. The 4-nitrophenol is selectively transferred to the aqueous phase through ionization, while the desired product remains in the organic phase, effectively separating the impurity without using adsorbents
2Manufacturing precision
If repeated adsorption is performed to remove 4-nitrophenol to a level that does not cause discoloration, then product purity is improved, but activated PEG is also adsorbed resulting in low yield
Solution Approach 1:
By changing the pH parameter to 10 or higher, the patent creates a condition where 4-nitrophenol is ionized and preferentially partitions into the aqueous phase. This single-step extraction achieves high purity without the need for repeated adsorption cycles, preventing loss of the activated PEG product and maintaining high yield
3Manufacturing precision
If a large amount of solvent is used for purification, then product purity can be improved, but the amount that can be produced at one time is limited due to equipment restrictions
Solution Approach 1:
The patent utilizes phase transition by adding a basic aqueous solution to create a two-phase system (organic phase containing activated PEG and aqueous phase containing ionized 4-nitrophenol). This phase separation enables efficient purification with minimal solvent volumes, allowing scaling to large production capacities without equipment restrictions
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 enables efficient and industrially viable production of high-purity activated polyethylene glycol compounds with reduced waste, effectively removing 4-nitrophenol impurities and allowing for large-scale production without the generation of adsorbent waste.
Implementation Method 1
adding a basic aqueous solution having a pH of 10 or more and 14 or less to the reaction mixture to obtain a two-phase mixture
Implementation Method 2
separating an organic layer of the two-phase mixture from an aqueous layer of the two-phase mixture and recovering the activated polyethylene glycol compound from the organic layer
Data Source
AI summary
A method for producing an activated polyethylene glycol compound having a carbamate bond between a polyethylene glycol moiety and a functional group capable of reacting with a bio-related substance or a precursor of the functional group, includes: reacting a polyethylene glycol raw material having a nitrophenyl group at a terminal thereof with an amine compound having the functional group capable of reacting with the bio-related substance or the precursor of the functional group in a solution containing an aprotic solvent to obtain a reaction mixture containing the activated polyethylene glycol compound and 4-nitrophenol; adding a basic aqueous solution having a pH of 10 or more and 14 or less to the reaction mixture to obtain a two-phase mixture; and separating an organic layer of the two-phase mixture from an aqueous layer of the two-phase mixture and recovering the activated polyethylene glycol compound from the organic layer.