Glycol Ether Solvent Antioxidant Selection for Peroxide Inhibition
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Solution Overview
Problem
The recent EPA decision to remove compounds inhibited with butylated hydroxytoluene (BHT) from the CleanGredients database poses a challenge for glycol ether solvents like DOWANOL™ DPnB, necessitating the development of a BHT alternative to prevent peroxide and acid generation in glycol ether solvents.
Innovation Solution
The use of low concentrations (50 ppm to 1000 ppm by weight) of antioxidants such as d,l-alpha-tocopherol, d,l-beta-tocopherol, d,l-gamma-tocopherol, and n-propyl gallate in glycol ether solvents to inhibit peroxide formation, maintaining the solvent's quality and meeting regulatory standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BHT is used as an antioxidant in glycol ether solvents, then peroxide inhibition is effective, but the solvent composition fails to meet EPA Safer Choice Standard criteria
Solution Approach 1:
The patent substitutes BHT with alternative antioxidants (tocopherols, propyl gallate) that have different chemical structures and properties, changing the compositional parameters of the solvent system to achieve both peroxide inhibition and EPA Safer Choice compliance
Solution Approach 2:
The patent uses antioxidants at low concentrations (50-1000 ppm) that can be depleted and replenished, providing a practical alternative to BHT that meets regulatory requirements while maintaining protective function
2Reliability
If antioxidants are added to glycol ether solvents, then peroxide formation is inhibited, but the solvent composition may fail to meet desired assay, acidity and color specifications
Solution Approach 1:
The patent optimizes antioxidant concentration parameters (50-1000 ppm range) to achieve peroxide inhibition while maintaining assay, acidity and color specifications within desired limits
Solution Approach 2:
The patent replicates the protective function of BHT using alternative antioxidant molecules (tocopherols, propyl gallate) that provide similar peroxide inhibition effectiveness without the regulatory compliance issues
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
These antioxidants effectively reduce peroxide and acidity levels in glycol ether solvents, ensuring compliance with specifications and maintaining the solvent's quality, as demonstrated by concentrations of peroxides below 20 ppm and APHA color indices less than 25, thus providing a viable alternative to BHT.
Implementation Method 1
The phenolic hydrogen atom of the hindered phenol antioxidant is transferred to the peroxide radical, forming a resonance-stabilized phenoxyl radical
Implementation Method 2
The phenoxyl radical is stabilized by resonance delocalization of the unpaired electron across the aromatic ring and oxygen atom
Implementation Method 3
The presence of bulky substituents at the ortho positions of the phenol ring provides steric hindrance that protects the phenolic hydrogen and stabilizes the phenoxyl radical
Data Source
AI summary
The present invention relates to solvent compositions and processes for inhibiting the generation of peroxide in glycol ether solvents. In one aspect, a solvent composition comprises at least one glycol ether, at least one antioxidant containing a hindered phenol, wherein the concentration of the antioxidant in the solvent composition is less than or equal to 1,000 ppm by weight, and a peroxide, wherein the concentration of the peroxide in the solvent composition is less than 20 ppm, and wherein the APHA color index of the solvent composition is less than 25.