Alpha-Hydroxycarboxylic Acid Ester Synthesis Using Boric Acid Catalyst
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Solution Overview
Problem
Existing methods for synthesizing alpha-hydroxycarboxylic acid esters face issues such as equipment corrosion, complex wastewater treatment, deep product color, and catalyst regeneration challenges, particularly when using cheap catalysts like sulfuric acid or solid acids.
Innovation Solution
A synthesis method involving alpha-hydroxycarboxylic acid, alcohol, and a catalyst like boric acid or metaboric acid, with a water-carrying agent, under controlled temperature and pressure, followed by catalyst recovery and neutralization, to produce a colorless alpha-hydroxycarboxylic acid ester with reduced wastewater discharge and lower production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If concentrated sulfuric acid or p-toluenesulfonic acid is used as catalyst, then esterification reaction efficiency is improved, but equipment corrosion and wastewater treatment complexity increase
Solution Approach 1:
The patent changes the chemical parameter of the catalyst from strong mineral acids (sulfuric acid, p-toluenesulfonic acid) to weak organic acid (boric acid), fundamentally altering the reaction system's properties. This parameter change maintains catalytic functionality while eliminating the corrosive effects associated with strong acids, thus resolving the contradiction between reaction efficiency and equipment corrosion.
2Productivity
If concentrated sulfuric acid or p-toluenesulfonic acid is used as catalyst, then esterification reaction efficiency is improved, but wastewater treatment complexity increases
Solution Approach 1:
By changing the catalyst from strong mineral acids to weak organic boric acid, the patent fundamentally alters the wastewater composition. The weak acid nature of boric acid produces less corrosive and easier-to-treat wastewater, reducing the complexity of wastewater treatment systems while maintaining high esterification reaction efficiency.
3Ease of manufacture
If solid acid catalyst is used, then catalyst recovery is simplified, but product color deepens
Solution Approach 1:
The patent changes the catalyst from solid acid to soluble boric acid, fundamentally altering the catalyst's physical state and chemical properties. This parameter change enables simple catalyst recovery through evaporation and crystallization while preventing the product color deepening issue associated with solid acid catalysts, thus resolving the contradiction between ease of manufacture and manufacturing precision.
4Object-affected harmful factors
If boric acid catalyst is used, then equipment corrosion and wastewater treatment are reduced, but catalyst activity may be lower
Solution Approach 1:
The patent optimizes the concentration parameter of boric acid catalyst to find the optimal balance between low corrosivity and high catalytic activity. By precisely controlling the catalyst concentration, the system achieves sufficient reaction efficiency while maintaining the advantages of using weak acid boric acid, thus resolving the contradiction between reduced harmful factors and maintained productivity.
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 produces high-purity, colorless alpha-hydroxycarboxylic acid esters with reduced alkali consumption and wastewater, improving product quality and simplifying catalyst recovery and reuse, while minimizing side reactions and production costs.
Implementation Method 1
adding alpha-hydroxycarboxylic acid, alcohol, a catalyst and a water-carrying agent into a reaction device with an oil-water separator according to a mass ratio of the alpha-hydroxycarboxylic acid:the alcohol:the catalyst:the water-carrying agent being 100:(20-400):(0.1-10):(0-500), stirring under normal pressure, performing an esterification reaction
Implementation Method 2
performing an esterification reaction at a temperature in a range of 100-160 Celsius degrees (° C.) for 3-10 hours, refluxing an oil layer in the oil-water separator
Implementation Method 3
distilling the water-carrying agent and unreacted alcohol when no water being produced in the oil-water separator, thereby obtaining a crude product
Implementation Method 4
performing vacuum fractionation on the neutral esterification product obtained in the step (3) to obtain a refined product of the alpha-hydroxycarboxylic acid ester
Data Source
AI summary
A synthesis method of alpha-hydroxycarboxylic acid ester is provided. In the method, an alpha-hydroxycarboxylic acid and an alcohol are taken as raw materials, one or more of boric acid, metaboric acid, pyroboric acid, and boric anhydride is taken as a catalyst, and one of cyclohexane, toluene, benzene, and alcohols is taken as a water-carrying agent. A reaction temperature is kept in range of 100-160° C., produced water is separated by an oil-water separator, and the alpha-hydroxycarboxylic acid ester is synthesized directly. After an esterification reaction, the water-carrying agent and unreacted alcohol are distilled by vacuum fractionation to obtain a crude product, and refined alpha-hydroxycarboxylic acid ester is obtained by performing neutralization, water washing, and vacuum rectification on the crude product. The alpha-hydroxycarboxylic acid ester prepared by the method has high purity and light color, and can be used as green solvent, surfactant, chiral resolution agent and plasticizer.