4-Hydroxyacetophenone Purification via Organic Solvent Crystallization
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Solution Overview
Problem
Current methods for purifying crude 4-hydroxyacetophenone, such as recrystallization from water and column chromatography, are inefficient and costly, leading to low production yields and high residual solvent content, making them unsuitable for industrial-scale production of highly pure, crystalline, and odorless 4-hydroxyacetophenone suitable for cosmetic applications.
Innovation Solution
A method involving mixing crude 4-hydroxyacetophenone with solvents like diethyl carbonate, dimethyl carbonate, ethanol, or cyclohexane, optionally with activated carbon, and controlling temperature for crystallization, followed by filtration and drying, to achieve high purity and improved solubility and flowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If recrystallization from water is used, then purification is achieved, but solvent consumption is very large (15-20 times the raw material quantity) and production efficiency is low
Solution Approach 1:
The patent changes the solvent parameter from water to organic solvents (ethyl acetate, ethanol, isopropanol, or their mixtures), which fundamentally alters the solubility characteristics and allows for much lower solvent-to-material ratios while achieving the same or better purification效果
Solution Approach 2:
The patent adopts and improves upon the recrystallization method previously used for pharmaceutical intermediates (paracetamol, ibuprofen) by adapting it to 4-hydroxyacetophenone purification, proving that organic solvent recrystallization can achieve high purity with reduced solvent consumption
2Manufacturing precision
If recrystallization from water is used, then purification is achieved, but the product is obtained as powder with bad flowability and easy caking
Solution Approach 1:
Changing the solvent from water to organic solvents alters the crystallization behavior and crystal habit of 4-hydroxyacetophenone, resulting in crystalline products with superior flowability and anti-caking properties compared to the powder form obtained from water recrystallization
3Manufacturing precision
If column chromatography is used, then high purity is achieved, but the sample volume is limited and solvent volume used is large
Solution Approach 1:
The patent extracts the purification function from the complex column chromatography process and implements it through a simple recrystallization process using organic solvents, achieving comparable or superior purity with dramatically reduced solvent consumption and without the limitation on sample volume
Solution Approach 2:
The patent replaces the expensive and complex column chromatography system with a simple, inexpensive recrystallization process using common organic solvents, making high-purity purification accessible for industrial-scale production
4Ease of manufacture
If water is used repeatedly in recrystallization, then cost reduction is attempted, but salt and phenol content increases continuously affecting product quality
Solution Approach 1:
The patent changes the solvent system from water to organic solvents (ethyl acetate, ethanol, isopropanol), which do not accumulate salts and phenols upon repeated use, thereby maintaining consistent product quality across multiple batches without the degradation issues encountered with water reuse
5Ease of operation
If small amounts of residual water remain in the final product, then some moisture is tolerated, but the color becomes darker and less attractive
Solution Approach 1:
The patent changes the solvent from water to organic solvents, eliminating the source of residual water in the final product. This prevents the darkening effect and maintains the light, attractive color of the purified 4-hydroxyacetophenone while still achieving complete purification
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 method yields 4-hydroxyacetophenone with a purity of at least 90% and reduced phenol content, enhancing its suitability for cosmetic use with superior solubility and flowability, while minimizing solvent consumption and production costs, making it suitable for industrial-scale production.
Implementation Method 1
mixing the crude 4-hydroxyacetophenone of step (a) with one or a mixture of two or more solvent(s)
Implementation Method 2
adding an adsorbent, preferably activated carbon, to the mixture obtained in step (b) or step (c)
Implementation Method 3
cooling of the mixture obtained in step (b) or step (c), if present, or further cooling of the mixture obtained in step (e), if step (d) is not present, or step (f), if present, to a temperature below the crystallization temperature of 4-hydroxyacetophenone to induce crystallization of 4-hydroxyacetophenone
Implementation Method 4
drying of the crystallized 4-hydroxyacetophenone obtained in step (h) or step (k)
Data Source
Figure 1a
Figure 1b
AI summary
The present invention relates to a method of purifying crude 4-hydroxyacetophenone and to a product comprising or consisting of crystallized 4-hydroxyacetophenone and one, two or more solvent(s), the product being obtained or obtainable by the above method.