Cyclic Ester Purification via Liquid-Liquid Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for purifying cyclic esters produced by heating depolymerization of hydroxycarboxylic acid oligomers are inefficient in terms of energy and yield, making it difficult to obtain high-purity cyclic esters suitable for bulk polymerization processes.
Innovation Solution
A method involving sequential liquid-liquid separation, washing with a low-boiling point organic solvent mutually soluble with the depolymerization solvent, and subsequent evaporation to recover high-purity cyclic esters with reduced solvent content, utilizing the energy from the co-distillate and minimizing external heat input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If recrystallization from organic solvent is used to obtain high-purity cyclic ester, then purity is improved, but energy efficiency and yield deteriorate
Solution Approach 1:
The invention changes the purification approach from solid-liquid recrystallization to liquid-liquid extraction followed by evaporation. By utilizing the solubility differences of cyclic ester in different organic solvents and controlling temperature parameters, the method achieves high purity (≥99.9 mol%) while improving energy efficiency and yield compared to traditional recrystallization methods
Solution Approach 2:
The invention employs phase transition of the organic solvent from liquid to vapor during the evaporation step to remove the solvent and obtain purified cyclic ester. This phase transition approach allows for efficient separation and purification with better energy efficiency compared to recrystallization
2Manufacturing precision
If recrystallization from organic solvent is used to obtain high-purity cyclic ester, then purity is improved, but yield deteriorates
Solution Approach 1:
By changing from recrystallization to liquid-liquid extraction followed by evaporation, the invention improves both purity and yield. The liquid-liquid extraction step efficiently separates cyclic ester from impurities based on solubility differences, and the subsequent evaporation step recovers the cyclic ester with minimal loss, achieving yield improvement alongside high purity
3Manufacturing precision
If washing with organic solvent mutually soluble with depolymerization solvent is used, then purification efficiency is improved, but thermal efficiency deteriorates due to evaporation requirements
Solution Approach 1:
The invention uses a low-boiling-point organic solvent as an intermediary substance that is mutually soluble with the depolymerization solvent. This intermediary solvent facilitates efficient liquid-liquid extraction of cyclic ester while its low boiling point enables energy-efficient evaporation, resolving the contradiction between purification efficiency and thermal efficiency
Solution Approach 2:
By selecting an organic solvent with specific parameters (low boiling point and mutual solubility with depolymerization solvent), the invention optimizes both purification efficiency and thermal efficiency. The parameter selection allows for effective separation during extraction and energy-efficient removal during evaporation
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 achieves high thermal and purification efficiency, allowing for the production of cyclic esters with purities of at least 99.9 mol% and residual solvent content below 10 ppm, suitable for high-molecular-weight aliphatic polyester production.
Implementation Method 1
evaporating the organic solvent from the cyclic ester phase containing the organic solvent to recover the cyclic ester
Implementation Method 2
subjecting a co-distillated liquid comprising a cyclic ester produced by heating depolymerization of a hydroxycarboxylic acid oligomer in the presence of a depolymerization solvent and the depolymerization solvent to liquid-liquid separation of separating the co-distillated liquid into a depolymerization solvent phase and a cyclic ester phase
Data Source
AI summary
A method of purifying a cyclic ester, comprising: mixing a co-distillated liquid comprising a cyclic ester produced by heating depolymerization of a hydroxycarboxylic acid oligomer in the presence of a depolymerization solvent and the depolymerization solvent with an organic solvent for washing which is mutually soluble with the depolymerization solvent and has a lower boiling point than the cyclic ester; subjecting the resultant mixture liquid to liquid-liquid separation into an organic solvent phase containing the depolymerization solvent and a cyclic ester phase containing the organic solvent; and then evaporating the organic solvent from the cyclic ester phase containing the organic solvent to recover the cyclic ester containing a reduced amount of the depolymerization solvent. As a result, purified cyclic ester is recovered at high heat efficiency, purification efficiency and operation efficiency, from the co-distillate liquid containing the depolymerization solvent and the cyclic ester from the depolymerization system for thermal decomposition of the hydroxycarboxylic acid oligomer in the presence of the depolymerization solvent.