Process for preparing hydrofluoroethers

Process for obtaining hydrofluoroethers of formula (I): A-(Rf)n0—CF(Rf1)—O—Rh (I) wherein a mono- or bifunctional carbonyl compound of formula (IV): B—Rf—C(O)Rf1 (IV) is reacted with at least one equivalent of a fluoroformate of formula (III) R—OC(O)F (III) in the presence of an ion fluoride compound (catalyst) and of a dipolar aprotic organic compound, liquid and inert under the reaction conditions