Fluorescein Quinoid Preparation via Mesylate Salt Conversion

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Solution Overview

Problem

The existing processes for preparing fluorescein quinoid form (Fls Q) face challenges in enhancing filtration behavior and achieving high purity, particularly at an industrial scale, due to issues with filtration problems and impurities like methane sulfonic acid residues.

Innovation Solution

A process involving the conversion of fluorescein mesylate salt or co-crystal into fluorescein quinoid form using water or a mixture of water and a water-soluble organic solvent, specifically through steps of preparation, washing, and recrystallization, to achieve enhanced filtration and purity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional processes are used to prepare fluorescein quinoid form, then the preparation is simpler, but filtration behavior is poor and purity is reduced

Engineering Contradiction:
Improvepurity of Fls QVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by first converting fluorescein into its mesylate salt form before obtaining the final quinoid form. This intermediate step prepares the material in a more filterable state, preventing filtration problems that would occur with direct preparation. The mesylate salt acts as a precursor that facilitates subsequent purification and filtration operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses an intermediary substance (mesylate salt) as a mediator in the preparation process. This intermediate compound serves as a bridge between the starting fluorescein and the final quinoid form, enabling better filtration behavior and purity. The intermediary form allows for effective washing to remove impurities like methane sulfonic acid residues.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If conventional processes are used to prepare fluorescein quinoid form, then the process is faster, but filtration problems occur especially at industrial scale

Engineering Contradiction:
Improveproduction efficiencyVSAvoidfiltration behavior
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent applies preliminary action by first converting fluorescein into its mesylate salt form before obtaining the final quinoid form. This intermediate step prepares the material in a more filterable state, preventing filtration problems that would occur with direct preparation. The mesylate salt acts as a precursor that facilitates subsequent purification and filtration operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the chemical state parameter of fluorescein by converting it to mesylate salt form. This parameter change (from neutral fluorescein to salt form) fundamentally alters the filtration behavior and solubility characteristics, enabling efficient filtration and washing operations while maintaining high productivity.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If conventional processes are used, then fewer washing steps are needed, but impurities like methane sulfonic acid residues remain

Engineering Contradiction:
Improvepurity of Fls QVSAvoidwashing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent changes the chemical state parameter of fluorescein by converting it to mesylate salt form. This parameter change (from neutral fluorescein to salt form) fundamentally alters the filtration behavior and solubility characteristics, enabling efficient filtration and washing operations while maintaining high productivity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses an intermediary substance (mesylate salt) as a mediator in the preparation process. This intermediate compound serves as a bridge between the starting fluorescein and the final quinoid form, enabling better filtration behavior and purity. The intermediary form allows for effective washing to remove impurities like methane sulfonic acid residues.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 process effectively improves the filtration behavior and purity of Fls Q, avoiding filtration issues and ensuring complete conversion by removing impurities, thus facilitating efficient industrial-scale production.

Implementation Method 1

converting the fluorescein mesylate salt or co-crystal into fluorescein quinoid form of formula (I) by treatment with water or a mixture of water and a water-soluble organic solvent

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 2

the preparation process and the specific fluorescein solid form according to the invention will become apparent from the below-reported description of preferred embodiments

Methodology Applied
Scientific EffectRecrystallization: Crystallisation

Data Source

PatentEP3604292B1Process for preparing fluorescein quinoid form
Publication Date: 2023.01.18 DELMAR CHEM LTD
  • EP3604292B1 patent drawingFigure 1A~1B
  • EP3604292B1 patent drawingFigure 2
  • EP3604292B1 patent drawingFigure 3A~3B

AI summary

The present invention relates to a process for preparing fluorescein quinoid form of Formula (I): Furthermore, the present invention relates to a new solid fluorescein form and a process for the preparation thereof. The present invention also relates to the use of said new solid fluorescein form in the synthesis of fluorescein quinoid form.