Hydroxide Chemoselectivity Changes with Water Microsolvation

Solvent molecules are known to affect chemical reactions, especially if they interact with one or more of the reactants or catalysts. In ion microsolvation, i.e., solvent molecules in the first solvation sphere, strong electronic interactions are created, leading to significant changes in charge distribution and consequently on their nucleophiicity/electrophilicity and acidity/basicity. Despite a long history of research in the field, fundamental issues regarding the effects of ion microsolvation are still open, especially in the condensed phase. Using reactions between hydroxide and relatively stable quaternary ammonium salts as an example, we show that water microsolvation can change hydroxide's chemoselectivity by differently affecting its basicity and nucleophilicity. In this example, the hydroxide reactivity as a nucleophile is less affected by water microsolvation than its reactivity as a base. These disparities are discussed by calculating and comparing oxidation potentials and polarizabilities of the different water-hydroxide clusters.

Automated summary

This study discusses the impact of solvent molecules on chemical reactions, particularly through the electronic interactions in ion microsolvation. Using the reaction between hydroxide and quaternary ammonium salts as an example, it demonstrates how water microsolvation can alter the chemical selectivity of hydroxide. The reactivity of hydroxide as a base is more affected by water microsolvation than its reactivity as a nucleophile.