Elemental fluorine. Part 14. Electrophilic fluorination and nitrogen functionalisation of hydrocarbons

Abstract

Selective fluorination of a range of hydrocarbons was achieved by reaction with either elemental fluorine or Selectfluor™, an electrophilic fluorinating reagent of the N–F class. An electrophilic mechanism is envisaged. On prolonged reaction, the strongly acidic reaction medium that is formed upon substitution of hydrogen by fluorine when Selectfluor™ is used as the fluorinating reagent, promotes loss of fluoride from the initial fluorinated product. Trapping of the subsequent carbocation by the acetonitrile solvent in a Ritter type process gives overall nitrogen functionalisation of hydrocarbons. Amidation of hydrocarbons could also be achieved in a one-stage process by reaction of the hydrocarbon with fluorine and a Lewis acid, such as boron trifluoride–diethyl ether, in acetonitrile.