Elemental fluorine and HOF·CH₃CN in service of general organic chemistry

At present, HOF·CH₃CN complex is the best oxygen transfer agent that chemistry has to offer. It is readily made by passing dilute fluorine through aqueous acetonitrile and does not require any isolation or purification. It is stable in aqueous acetonitrile solution for a few hours at room temperature, providing ample opportunities for various reactions. Epoxidation of regular olefins as well as of very electron-depleted ones proceeds smoothly. HOF·CH₃CN transfer oxygen also to heteroatoms, especially sulfur and nitrogen. Even very electron-depleted sulfides such as R_fSAr that are very difficult to oxidize, are converted into the respective sulfones in a matter of minutes. On the other hand, since the reaction conditions are very mild, the reagent can oxidize various thiophenes and amino acids to the corresponding S,S-dioxides and α-nitro acid derivatives. HOF·CH₃CN was also instrumental in ending the 50 years quest for making the elusive 1,10-phenanthroline N,N-dioxide and for the novel transformation of azides to nitro derivatives. The use of BrF₃ for making symmetric esters and of tBuOF as an electrophilic tert-butoxylation agent is also mentioned.