A process comprising for example reacting a substituted or unsubstituted arylamine or a mixture thereof with a Vilsmeier reagent in a solvent system comprising acetonitrile as a sole solvent or a solvent system comprising acetonitrile and one or more solvents selected from toluene, xylene, chlorobenzene, dichlorobenzene, dichloromethane, 1,2-dichloroethane, or a combination thereof.