Methylation of 1,8-dihydroxy-9,10-anthraquinone with and without use of solvent-free technique

A convenient and environmentally friendly solvent-free procedure has been developed for dimethylation of 1,8-dihydroxy-9,10-anthraquinone with excellent yield. A highly selective monomethylation of 1,8-dihydroxy-9,10-anthraquinone in refluxing tetraglyme makes monomethylated peri-dihydroxy-9,10-anthraquinones easily available. Alternatively, irradiation in a domestic microwave oven has been employed for the solvent-free monomethylation of 1,8-dihydroxy-9,10-anthraquinone.