Purifying N-alkylpyrrolidone via Basic Compound Treatment
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Solution Overview
Problem
Existing methods for purifying N-alkylpyrrolidones, particularly N-methylpyrrolidone, used in lithium ion accumulator production are inefficient in removing impurities with similar boiling points, such as those of formulas I and II, which are difficult to separate and require high purity for long-lived accumulator production.
Innovation Solution
A process involving the addition of a basic compound, such as sodium hydroxide, to the N-alkylpyrrolidone, followed by rapid heating to at least 80°C within 20 minutes, and subsequent distillation to separate and purify the N-alkylpyrrolidone, effectively removing impurities and allowing for reuse in lithium ion accumulator production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation methods are used to purify N-alkylpyrrolidone, then the purification process is simple, but impurities with similar boiling points (formulas I and II) cannot be effectively removed
Solution Approach 1:
The patent changes the chemical environment by adjusting pH parameters (adding acid or base) to convert impurities into water-soluble forms. This parameter change enables selective separation of impurities with similar boiling points through liquid-liquid extraction, achieving both high purity and efficient removal of formulas I and II impurities.
Solution Approach 2:
The patent introduces an intermediary substance (acid or base) that mediates the separation process. The acid or base reacts with impurities to form water-soluble salts, acting as a mediator that enables selective extraction into aqueous phase, thereby separating impurities from N-alkylpyrrolidone despite similar boiling points.
2Manufacturing precision
If multiple purification steps are implemented to remove impurities, then purity increases, but process complexity and time increase
Solution Approach 1:
The patent combines multiple purification functions into a single integrated process step. By adding acid or base and performing liquid-liquid extraction in one operation, the method simultaneously removes multiple types of impurities (formulas I and II) that would otherwise require multiple separate purification steps, reducing both process complexity and time.
Solution Approach 2:
The patent employs a universal purification approach using acid or base treatment that can remove multiple different impurities (formulas I and II) through a single mechanism. This multi-functional method eliminates the need for different specialized purification steps for different impurity types, simplifying the overall process.
3Productivity
If N-alkylpyrrolidone is reused without thorough purification, then productivity is maintained, but accumulator longevity and performance deteriorate
Solution Approach 1:
The patent uses parameter changes (pH adjustment) to achieve thorough purification that enables safe reuse. By converting impurities into water-soluble forms through acid or base treatment, the method ensures complete removal of degradation-causing impurities, allowing N-alkylpyrrolidone to be reused multiple times while maintaining accumulator longevity and performance.
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 process achieves high-purity N-alkylpyrrolidone suitable for repeated use in lithium ion accumulator production, significantly reducing impurity content and ensuring the necessary purity and water freedom, thereby enhancing the longevity and performance of lithium ion accumulators.
Implementation Method 1
The separation is effected by liquid-liquid extraction in presence of a basic compound
Implementation Method 2
the temperature of the mixture is at least 80° C. not more than 20 minutes after addition of the basic compound
Implementation Method 3
the N-alkylpyrrolidone is distilled off from the mixture obtained
Data Source
AI summary
Process for purifying N-alkylpyrrolidones which due to a previous use comprise at least one of the impurities of the formula I or IIwhere R is hydrogen or a C1-C20-alkyl group,whereina basic compound is added to the N-alkylpyrrolidone to be purified and the temperature of the mixture is at least 80° C. not more than 20 minutes after addition of the basic compound andN-alkylpyrrolidone is distilled off from the mixture obtained.