Tautomer Crystallisation via Methanol Solvent Switch

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Solution Overview

Problem

Existing methods for preparing the tautomer of Formula 1, effective for skin protection against UVA and UVB radiation, are hindered by the complexity and cost associated with using ethanol as a solvent due to tax constraints.

Innovation Solution

A process involving the crystallization of the tautomer mixture obtained by reacting cyanuryl chloride with 2-ethylhexyl p-aminobenzoate in xylene, followed by gradual addition to methanol, which is more cost-effective and legislatively convenient than ethanol, allowing for the production of the tautomer in a molten state and subsequent cooling and filtration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ethanol is used as solvent for crystallisation, then the crystallisation process works effectively, but the cost increases and legislative constraints are imposed due to tax controls

Engineering Contradiction:

Improvecrystallisation effectivenessVSAvoidcost and legislative compliance

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the solvent parameter from ethanol to methanol, altering the chemical composition to eliminate tax constraints while maintaining crystallisation effectiveness. This substitution resolves the contradiction by finding an alternative solvent that achieves the same technical result without the legislative and cost burdens.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If methanol is used as solvent, then cost decreases and legislative constraints are removed, but the crystallisation process must be optimized for new solvent properties

Engineering Contradiction:

Improvecost and legislative complianceVSAvoidprocess optimization requirements

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent systematically adjusts process parameters including solvent ratio (25-35% methanol in reaction mixture), temperature ranges (cooling to 15-25°C), and addition rates to optimize crystallisation in methanol. These parameter adjustments resolve the contradiction by adapting the process to the new solvent's properties while maintaining effectiveness.

Inventive Principle:

Principle #35Parameter changes

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 efficiently produces the tautomer of Formula 1, as demonstrated by IR spectra, overcoming the limitations of ethanol use and providing a cost-effective and legislatively compliant process for sunscreen production.

Implementation Method 1

crystallisation from methanol of the tautomer mixture obtained by reacting cyanuryl chloride with 2-ethylhexyl p-aminobenzoate

Methodology Applied

Scientific EffectCrystallisation: Crystallisation

Implementation Method 2

The methanol solution can be filtered before cooling (to about 15°C)

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentEP4253368A1Process for the preparation of tautomeric forms of sunscreens

Publication Date: 2023.10.04 3V SIGMA

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AI summary

The compound of Formula 1 is obtained efficiently and cheaply from the mixture of tautomeric forms by crystallisation from methanol.