Process for the preparation of aromatic alpha-hydroxyketones that does not require the use of chlorine, sulfuryl chloride or bromine and comprises the halogenation of an intermediate aromatic ketone with a hydrogen halide in the presence of an oxidising compound. The inventive composition is soluble in aqueous base solutions and insoluble in water. Other projects are shown in the background, enabling users to easily and quickly switch between projects and be informed about actions occurring in the background tasks. The fiber optic delivery device comprises one or more waveguides, preferably optical fibers. The difference between the effective contact areas of the first endodontic instrument and second endodontic instrument being substantially the same as the difference between the effective contact areas of the second endodontic instrument and third endodontic instrument.