Rate and Yield Enhancements in Nucleophilic Aromatic Substitution Reactions via Mechanochemistry

Abstract

A variety of nucleophilic aromatic substitution reactions were carried out mechanochemically to great advantage. On average, reactions rates were nine-times faster. The corresponding kinetic studies presented provide the clearest head-to-head kinetic comparisons between mechanochemical and conventional systems at identical temperatures. Attempts are provided at classifying the kinetics of one example. Removal of polar, protic solvents from these reactions presents environmental benefits to a reaction class whose kinetics are heavily dependent on such solvents.

Sustainability Assessment of Mechanochemistry by Using the Twelve Principles of Green Chemistry

“…[132] On the other hand, the development of thermally controlled mechanochemical ball milling has also enabled the operation of ball mills at elevated temperatures. [40,[133][134][135][136] These studies have demonstrated that a moderate increase in the temperature of ball milling reactions can lead to a significant acceleration of the transformations, shortening the total milling times from hours to minutes and therefore representing an overall reduction in energy usage.…”

One-step hydroxylation of aryl and heteroaryl fluorides using mechanochemistry

“…It is also worth mentioning that, although many organic reactions have been already investigated with mechanochemical techniques, 14 this is not the case for S N Ar reactions, which remain underexplored with ball milling procedures. 19,20…”

Solvent-Minimized Synthesis of 4CzIPN and Related Organic Fluorophores via Ball Milling

“…Several of these reaction criteria can potentially be addressed by ball milling techniques, where it appears that in the absence of a reaction solvent, bases with lower than typical p K a values are still effective, and rigorously inert reaction conditions are not always necessary. For these reasons, mild, efficient, and sustainable synthetic strategies toward valuable 4CzIPN and 4CzIPN-type systems exploiting ball milling techniques via a solvent-minimized S N Ar pathway would be of interest to academic and industrial teams alike, and herein we wish to report our findings (Scheme C).…”