On-Water Selectivity Switch in Microdroplets in the 1,2,3-Triazole Synthesis from Bromoethenesulfonyl Fluoride

Water profoundly affects many organic
reactions by accelerating
them or changing their selectivity. Performing reactions “on-water”
offers an intriguing opportunity to influence chemical reactivity.
A nebulizer plume is an efficient way of generating microdropletsthe
uniquely complex reaction environment which opens alternative possibilities
that are not readily accessible in bulk emulsions. We describe the
on-water switch of chemoselectivity in the formation of triazoles
controlled by the on-water environment in dual spray. These conditions
facilitate elimination of H–SO2F from the triazoline
intermediate, whereas the reaction in organic solvents results in
the exclusive HBr elimination. The influence of two-phase conditions
was investigated to obtain the best reaction efficiency, and the crucial
importance of the water/organic interface interactions was verified
by pH variation and D2O use.