P-Methoxybenzoic Acid Solubility in Polyol Solutions
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Solution Overview
Problem
The low solubility of p-methoxybenzoic acid in aqueous systems and the irreversible crystallization of its salts at high concentrations and low temperatures pose challenges in manufacturing and storing concentrated aqueous solutions, limiting its use in cosmetic and food industries.
Innovation Solution
A liquid, approximately neutralized combination of p-methoxybenzoic acid with polyols like glycerol, esters of polyglycerol, and salts of organic acids such as levulinic acid or citric acid, which form reversible and thermodynamically stable solutions when warmed to room temperature, improving solubility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If p-methoxybenzoic acid is used in high concentrations in aqueous systems, then the effectiveness and stability of cosmetic formulations is improved, but the solubility limit is exceeded causing irreversible crystallization
Solution Approach 1:
The patent introduces polyols (glycerol, propylene glycol, butylene glycol) and their esters as intermediary substances that mediate between p-methoxybenzoic acid and water. These intermediaries enhance the solubility of p-methoxybenzoic acid in aqueous systems through co-solvency effects, allowing high concentrations (up to 80% w/w) without irreversible crystallization. The intermediaries modify the solvent properties of water to accommodate the poorly water-soluble active ingredient.
Solution Approach 2:
The patent creates composite aqueous formulations combining p-methoxybenzoic acid with polyols and their esters. This composite approach allows the system to achieve properties that individual components cannot provide alone - specifically, maintaining high concentration of the active ingredient while preventing crystallization through the synergistic effects of the polyol mixture.
2Ease of operation
If salts of p-methoxybenzoic acid are used to improve solubility, then ease of dissolution is improved, but irreversible crystallization occurs at high concentrations and low temperatures
Solution Approach 1:
The patent uses polyols as intermediary substances that prevent the irreversible crystallization of p-methoxybenzoic acid salts. The polyols interfere with the crystal lattice formation through hydrogen bonding and steric effects, keeping the salts in solution even at high concentrations and low temperatures. This intermediary approach maintains both ease of dissolution and storage stability.
Solution Approach 2:
The patent modifies the physical-chemical parameters of the aqueous system by adding polyols, which change the solvent properties including dielectric constant, viscosity, and hydrogen bonding capacity. These parameter changes allow the system to maintain salt solubility across a wider range of temperatures and concentrations without crystallization.
3Ease of manufacture
If conventional aqueous formulations are used, then manufacturing simplicity is maintained, but solubility and stability of concentrated solutions are limited
Solution Approach 1:
The patent develops composite aqueous formulations that combine p-methoxybenzoic acid with specific polyols and their esters in defined ratios. This composite approach maintains manufacturing simplicity while dramatically improving solubility - the formulation can be prepared by simple mixing without complex processing steps, yet achieves solubility enhancement through the synergistic composite effect of the polyol mixture.
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 combination allows for the creation of thermally stable, high-concentration aqueous solutions of p-methoxybenzoic acid, preventing irreversible crystallization and enhancing the formulation's stability against microbial growth, making it suitable for long-term storage and use in cosmetic products.
Implementation Method 1
A liquid, approximately neutralized combination of p-methoxybenzoic acid with polyols like glycerol, esters of polyglycerol, and salts of organic acids such as levulinic acid or citric acid, which form reversible and thermodynamically stable solutions when warmed to room temperature, improving solubility and stability.
Implementation Method 2
A liquid, approximately neutralized combination of p-methoxybenzoic acid with polyols like glycerol, esters of polyglycerol, and salts of organic acids such as levulinic acid or citric acid, which form reversible and thermodynamically stable solutions
Implementation Method 3
In these solutions crystals may form at low temperatures, but in contrast to simple aqueous systems, will reversibly form a clear and homogeneous solution when warmed up to room temperature.
Data Source
AI summary
The present invention is related to concentrated aqueous solutions of p-methoxybenzoic acid and their production.