Classical reagent for cleavage of aryl methyl ethers at 200-220 o : Ber ., 75, 445 (1942), avoiding the strongly acidic or basic conditions of some alternative methods; see, e.g.: J. Org. Chem., 27, 4660 (1962).Demethylation of methyl aryl ethers can also be carried out under solvent-free conditions with microwave irradiation: J. Chem. Res. (Synop.), 394 (1999). Epoxides at ambient temperature in chloroform give chlorohydrins: Synth. Commun., 11, 287 (1981). In DMF, has been used for the conversion of alkyl tosylates to chlorides at room temperature: J. Am. Chem. Soc., 80, 2726 (1958). Cleaves N-trityl groups from histidine residues in peptide synthesis: Tetrahedron Lett., 28, 6031 (1987). Mild acid catalyst, e.g. in the formation of acetals with ethylene glycol: J. Org. Chem., 31, 26 (1966), or 1,3-propanediol: Bull. Soc. Chim. Fr., 2287 (1972); and in the Fischer indole synthesis for acid-sensitive substrates: Synthesis, 645 (1977).