Abstract: A process is provided for the fluorination of an aromatic fused ring compound which comprises treating the compound with fluorine. A preferred process involves treating a solution of a naphthalene compound in an inert solvent with elemental fluorine, preferably comprised in a gas stream and diluted with an inert gas. The process provides a convenient and simple method by which fluorinated derivatives may be prepared with a high degree of specificity and shows improved yields over methods known from the prior art.

Abstract: A process for the preparation of a perfluoropolyether having a general formula: ##STR1## as defined hereinbefore, which process includes the direct fluorination with elemental fluorine of a polyether having a general formula: ##STR2## as defined hereinbefore, wherein the fluorination is carried out in the presence of a solvent which is an ether having at least one substituent R.sub.F, wherein R.sub.F is a fluorinated hydrocarbon group. The said solvent ether is preferably a fluorinated volatile ether. The said solvent ether preferably has at least two groups R.sub.F which may be the same or different groups. Each group R.sub.F preferably has from two to four carbon atoms and at least two fluorine atoms. The said solvent ether may be an alicyclic ether having from 3 to 5 carbon atoms in its alicyclic ring.