Dichlorophenol Separation via Fractional Liquid-Liquid Extraction
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Solution Overview
Problem
Current processes for producing dichlorophenols, such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 3,6-dichloro-2-methoxybenzoic acid (dicamba), face challenges with high raw material costs, low process conversions, and significant waste generation, particularly due to difficulties in separating 2,4-dichlorophenol from other dichlorophenols like 2,5-dichlorophenol, which are not efficiently addressed by conventional distillation techniques.
Innovation Solution
A fractional liquid-liquid extraction process involving a rectifying and stripping section, using an organic solvent and an aqueous base solution, effectively separates 2,4-dichlorophenol and 2,5-dichlorophenol by transferring 2,5-dichlorophenol to the aqueous phase and 2,4-dichlorophenol to the organic phase, achieving enriched fractions with reduced need for additional separation operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation techniques are used to separate dichlorophenols, then the separation process is simple to implement, but the separation efficiency is poor because boiling points are within a few degrees of each other
Solution Approach 1:
The patent changes the separation parameter from temperature-based distillation to pH-based extraction. By adjusting the pH of the aqueous phase, the patent achieves selective extraction of 2,5-dichlorophenol as its salt form into the aqueous layer, while 2,4-dichlorophenol remains in the organic phase. This parameter change resolves the contradiction by achieving high separation efficiency without requiring complex distillation equipment.
Solution Approach 2:
The patent introduces an intermediary substance (aqueous base solution) that facilitates selective separation. The base solution reacts with 2,5-dichlorophenol to form a water-soluble salt, acting as a mediator that enables selective transfer to the aqueous phase. This intermediary approach achieves effective separation without the need for complex distillation apparatus.
2Productivity
If conventional extraction processes are used, then one component can be enriched, but additional separation operations are required to recover multiple purified fractions
Solution Approach 1:
The patent segments the separation process into two distinct sections: a rectifying section that enriches 2,4-dichlorophenol in the organic phase, and a stripping section that enriches 2,5-dichlorophenol in the aqueous phase. This segmentation allows simultaneous recovery of both purified fractions in a single integrated process, eliminating the need for additional separation operations and improving overall productivity.
Solution Approach 2:
The patent adds a vertical dimension to the extraction process by implementing a column with distinct rectifying and stripping sections at different heights. The feed enters at an intermediate point, with the rectifying section above and stripping section below. This dimensional arrangement enables simultaneous counter-current extraction in both sections, achieving dual enrichment in one operation.
3Manufacturing precision
If high purity fractions are achieved through multiple separation operations, then manufacturing precision is improved, but process cost and waste generation increase
Solution Approach 1:
The patent implements continuous counter-current extraction where the organic phase flows continuously through the rectifying section and the aqueous phase flows continuously through the stripping section. This continuous operation maintains high purity fractions while minimizing waste, as both phases are constantly regenerated and reused throughout the process rather than requiring batch processing with multiple discrete separation steps.
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 enhances process economics by achieving enriched extracts of both 2,4-dichlorophenol and 2,5-dichlorophenol, improving overall yield and reducing waste, and allows for the efficient recycling of unreacted 2,4-dichlorophenol, thereby addressing the limitations of existing separation methods.
Implementation Method 1
A fractional liquid-liquid extraction process involving a rectifying and stripping section, using an organic solvent and an aqueous base solution, effectively separates 2,4-dichlorophenol and 2,5-dichlorophenol by transferring 2,5-dichlorophenol to the aqueous phase and 2,4-dichlorophenol to the organic phase
Data Source
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AI summary
Various processes for the separation of a mixture containing dichlorophenols are described. In various aspects, the present invention relates to separation processes that produce an extract enriched in 2,4-dichlorophenol content and an extract enriched in 2,5-dichlorophenol content. The present invention further relates to various processes that integrate with these separation processes, such as a process for producing 3,6-dichloro-2-methoxybenzoic acid (dicamba) or salt or ester thereof or a process for producing 2,4-dichlorophenoxyacetic acid (2,4-D) or salt or ester thereof.