Synthesis of Xanthene Derivatives over Acid Activated Clay in Kerman Province and Kinetic Modeling

Abstract

14-aryl-14H-dibenzo[a,j]xanthenes are extensively used as dyes, pH-sensitive fluorescent material for visualization of biomolecules, and in laser technologies. The synthesis of aryl-14H-dibenzo[a,j]xanthene derivatives is studied using acid activated clay as reusable eco-friendly catalyst under solvent free condition. The reaction is carried out by hydrochloric acid activated clay. Clay is supplied from Kheirabad mine in Kerman province, Iran. Activation is done by 1, 2, 3, and 5 mol/L HCl. Among these catalysts, clay activated by 3 mol/L HCl was found to be a better catalyst which could be reused without any further chemical treatment eliminating the effluent disposal problems. The procedure offers advantages such as shorter reaction time, excellent yields, inexpensive catalyst, environment-friendly, and reusability of catalyst. The reaction obeys the Eley–Rideal type of mechanism. A theoretical kinetic model was developed for the evaluation of this slurry reaction. The effects of various parameters on the rate of reaction were evaluated. The reaction was found to be intrinsically controlled and there were no intraparticle as well as interaparticle mass transfer limitation on the rate of reaction.