Ionic Liquid-Assisted Grinding: An Electrophilic Fluorination Benchmark.

Area of Science:

• Organic Chemistry
• Green Chemistry
• Mechanochemistry

Background:

• Mechanochemical fluorination offers a solvent-free alternative for introducing fluorine into organic molecules.
• F-TEDA-BF4 is a common reagent for electrophilic fluorination.
• Optimizing reaction conditions is crucial for efficiency and selectivity.

Purpose of the Study:

• To investigate the impact of liquid additives, specifically ionic liquids, on mechanochemical fluorination.
• To compare the efficacy of various ionic liquids and molecular solvents as additives.
• To develop an improved protocol for efficient isolation of fluorinated products.

Main Methods:

• Mechanochemical grinding of aromatic and 1,3-dicarbonyl compounds using F-TEDA-BF4.
• Addition of catalytic amounts of various ionic liquids and molecular solvents.
• Analysis of reaction rates, selectivity, and product yields.
• Isolation of products via vacuum sublimation.

Main Results:

• Substoichiometric quantities of ionic liquids significantly increase reaction rates.
• Ionic liquid additives facilitate high yields and selectivity in fluorination.
• A lower viscosity of ionic liquid additives correlates with higher yields and difluorination.
• Ionic liquids featuring fluorous anions (triflate, triflimide) demonstrate superior catalytic activity.
• The developed protocol allows for easy and efficient product isolation.

Conclusions:

• Ionic liquids are effective catalysts for enhancing mechanochemical fluorination.
• The choice of ionic liquid additive critically influences reaction outcomes and process efficiency.
• Fluorous anion-based ionic liquids represent a promising class of catalysts for sustainable fluorination.