Evidence for the SN2′ mechanism in hydrolysis of C60F48: origin of the stability of trannulenes

Abstract

The products of hydrolysis of C₆₀F₄₈ (which contains six isolated double bonds) by either aq. acetone or aq. THF show that no more than twelve fluorines are replaced through nucleophilic substitution, as predicted by the recently identified S_N2′ mechanism. Subsequent HF elimination gives fragments containing a maximum of six epoxide oxygens. Calculated heats of formation of models for the possible initial hydroxy derivatives indicate that there is little energetic discrimination between them, so that a complex mixture is likely to be formed. Overall the data show that hydrolytic degradation of fluorofullerenes is less severe than believed previously, requires a specific motif, and explains the low susceptibility of C₆₀F₁₈ towards hydrolysis and the high stability of trannulenes.