Diol Purification via Hydrolysis and Reduction
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Solution Overview
Problem
Current methods for purifying diols, such as 1,4-butanediol, face challenges in removing acetals like HB-THF due to their close boiling points and azeotrope formation, leading to inefficient separation and product loss during distillation, especially when aiming for high purity and productivity.
Innovation Solution
A process involving hydrolysis of diol-acetal mixtures followed by treatment with a reducing agent to convert acetals into aldehydes or ketones, which are then reduced to diols, effectively purifying diols with high efficiency and minimizing losses, particularly suitable for 1,4-butanediol purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to separate diols from acetals, then separation is attempted, but the close boiling points and azeotrope formation lead to inefficient separation and product loss
Solution Approach 1:
The patent changes the chemical state of the acetal impurity by converting it to a different compound through hydrolysis and reduction reactions. Instead of relying on physical separation based on boiling point differences, the process chemically transforms the acetal into an aldehyde/ketone and then into a diol or alcohol with different properties, enabling effective separation and eliminating the azeotrope problem that causes product loss during distillation
Solution Approach 2:
The patent introduces intermediate chemical compounds (aldehydes and ketones) as mediators in the purification process. The acetal is first hydrolyzed to form an aldehyde or ketone, which serves as an intermediate state before being reduced to the final diol or alcohol product. These intermediates have different physical and chemical properties that facilitate separation from the target diol
2Manufacturing precision
If multiple distillation stages are used to achieve high purity, then separation efficiency improves, but productivity decreases due to time-consuming operations
Solution Approach 1:
The patent replaces the mechanical/physical separation system (multiple distillation stages) with a chemical transformation system. Instead of using repeated thermal processes to gradually enrich the diol purity, the process uses chemical reactions (hydrolysis and reduction) to convert impurities into separable or benign forms in a single or limited number of steps, dramatically reducing processing time while achieving the same or better purity levels
3Manufacturing precision
If distillation is performed to remove acetals, then acetal content decreases, but diol yield decreases due to co-distillation and azeotrope formation
Solution Approach 1:
The patent converts the harmful effect of acetal presence (which causes azeotrope formation and makes distillation inefficient) into a benefit by chemically transforming the acetal through hydrolysis and reduction. The acetal is converted into compounds that can be easily separated or that revert to the desired diol form, turning the purification challenge into an opportunity for high-yield recovery with minimal product loss
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 diols with an APHA colour index below 25, stability at high temperatures, and in acidic environments, while minimizing product loss and increasing yield, making them suitable for polymerization processes.
Implementation Method 1
reduction of the aldehydes and/or ketones present in the hydrolysis product in step (a) by the addition of a reducing agent, resulting in the diol of the same species as is present in the starting mixture
Implementation Method 2
hydrolysis of the mixture comprising at least one diol and at least one acetal thereof, resulting in the formation of the relative aldehydes and/or ketones and the relative diols
Data Source
AI summary
Process for purifying a mixture of a diol and an acetal, comprising hydrolysing the mixture with formation of the relative aldehydes/ketones and diols; and reducing the aldehydes/ketones present in the hydrolysis product by adding a reducing agent, resulting in a diol of the same species as present in the starting mixture.