Hossein Eshghi - Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad
M Eftekhar - Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad ۹۱۷۷۵-۱۴۳۶, Iran.
M Rahimizadeh - Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad ۹۱۷۷۵-۱۴۳۶, Iran.
M Hassanpour - Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad ۹۱۷۷۵-۱۴۳۶, Iran.
M Bakavoli - Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad ۹۱۷۷۵-۱۴۳۶, Iran.

Cobalt hydrogensulfate is an efficient catalyst for the condensation of β-naphthol, aromatic aldehydes and ۵,۵-dimethyl-۱,۳-cyclohexanedione at ۱۲۰ °C to afford ۹,۹-dimethyl-۱۲-phenyl-۸,۱۰,۱۱,۱۲-tetrahydro-۹-H-benzo[a]xanthen-۱۱-one derivatives in high yields. Also, polycondensation reactions of phenols with phthalic anhydride were carried out in the presence of cobalt hydrogensulphate under solvent-free conditions. Simple and convenient procedure, high conversion, reusability of catalyst, easy purification and short reaction time are the advantageous features of this method.

Cobalt hydrogensulfate, Heterogeneous and reusable catalyst, Xanthene derivatives, Solvent free