4-Dodecylbenzenesulfonic acid (DBSA) as an efficient and recyclable catalyst for synthesis of 14-aryl- and 14-alkyl-14-H-dibenzo [a,j]xanthenes under solvent-free conditions

14-Aryl- and 14-alkyl-14-H-dibenzo [a,j]xanthenes are prepared from the reaction of aromatic- and aliphatic aldehydes with B-naphthol in the presence of catalytic amounts of 4-dodecylbenzenesulfonic acid(DBSA) as a surfactant-type Br?nsted acid catalyst in toluene and under solvent-free conditions in excellent yields and short reaction times. The catalyst was recovered and reused for five successive times without considerable loss in its activity.