Crystallization of 2-(4'-Diethylamino-2'-Hydroxybenzoyl)benzoic Acid Hexyl Ester
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Solution Overview
Problem
Current processes for isolating 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester result in high phthalic acid dialkyl ester and colored impurity content, requiring additional purification steps and leading to handling challenges due to the formation of by-products like phthalic acid dihexyl ester and Rhodamine B type dyes, which are harmful and cause undesired discoloration.
Innovation Solution
A process involving dissolving the mixture in a solvent with a boiling point of up to 110°C, cooling to 20-40°C, optionally adding seed crystals, further cooling to below 5°C, and filtering to isolate the compound in crystalline form, which reduces phthalic acid dialkyl ester and colored impurity content, resulting in a safer and more convenient handling form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional synthesis and isolation processes are used, then 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester is produced, but the product contains high levels of phthalic acid dialkyl ester and colored impurities requiring additional purification steps
Solution Approach 1:
The patent combines multiple purification objectives (removing phthalic acid dialkyl ester and colored impurities) into a single crystallization step. By optimizing the crystallization conditions, the process simultaneously achieves removal of both impurity types, eliminating the need for separate purification steps while maintaining high product purity.
Solution Approach 2:
The patent employs parameter changes in the crystallization process, specifically controlling temperature, solvent composition, and cooling rate to optimize impurity removal. By adjusting these parameters, the process achieves selective crystallization of the desired product while keeping impurities in the mother liquor, thereby improving manufacturing precision without adding process complexity.
2Manufacturing precision
If additional purification steps are added to reduce phthalic acid dialkyl ester and colored impurities, then product purity increases, but processing time and operational complexity increase
Solution Approach 1:
The patent merges multiple purification functions into a single crystallization operation, achieving removal of both phthalic acid dialkyl ester and colored impurities simultaneously. This consolidation reduces the number of sequential steps required, thereby decreasing total processing time while maintaining high product purity.
Solution Approach 2:
The optimized crystallization process exhibits self-purification characteristics where the controlled crystallization conditions automatically favor selective product crystallization while rejecting impurities. This self-service mechanism reduces the need for additional intervention steps, saving time and simplifying operations.
3Ease of operation
If product is bottled as melt without crystallization, then handling is simplified, but product stability and safety are compromised due to high impurity content
Solution Approach 1:
The patent uses parameter changes in the crystallization process (temperature, solvent composition) to produce a crystalline product with significantly reduced impurity content. The resulting crystals are safer and more stable while maintaining ease of handling, resolving the contradiction between handling convenience and product safety.
Solution Approach 2:
The patent converts the potentially harmful impurities into a separable phase during crystallization. By controlling crystallization conditions, impurities are excluded from the crystal lattice and remain in the mother liquor, transforming the harmful mixture into a pure crystalline product that is both safe and easy to handle.
4Manufacturing precision
If crystallization is performed at lower temperatures to improve purity, then impurity content decreases, but energy consumption and process complexity increase
Solution Approach 1:
The patent optimizes the crystallization temperature parameter to achieve the best balance between purity and energy consumption. By selecting an optimal temperature range and using controlled cooling rates, the process achieves high purity products without excessive energy input, resolving the contradiction between manufacturing precision and energy usage.
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
The process achieves a purity of at least 99% with phthalic acid dialkyl ester content below 15 ppm and colored impurities below 1 ppm, providing a free-flowing crystalline product that is safer and easier to handle.
Implementation Method 1
dissolving a mixture comprising 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester in a solvent having a boiling point of at most 110°C to obtain a solution
Implementation Method 2
cooling the solution to a temperature below 5°C to obtain a suspension
Implementation Method 3
cooling the solution to a temperature in the range of from 20 to 40°C
Data Source
AI summary
The present invention relates to a process for isolating 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester with a high purity and low phthalic acid dialkyl ester content.