Disclosed is a method of chlorinating a side chain of a aromatic or heterocyclic ether. The aromatic or heterocyclic ether is mixed with a fluorine-containing aliphatic solvent. The aromatic or heterocyclic ether is contacted with chlorine radical at an elevated temperature which results in its chlorination. The chlorinated product is preferably insoluble in the solvent and separates, forming two phases. The solvent phase can be recycled and reused.