|
Abstract
|
Green chemistry has now attained the status of a major scientific discipline1 and studies in this area have led to the development of cleaner and more benign chemical processes, with many new technologies being developed each year. Much effort has been devoted to the use of non-traditional solvents for chemical Tetraketones. In addition to solvent-free media,2–3 these unconventional media include water,4 supercritical CO2,5 perfluorinated solvents6 and ionic liquids.7–9 The use of water as a medium for organic reactions is one of the latest challenges for modern organic chemists. It will be a major step forward to carry out organic reactions in water for environmental and economic reasons. Furthermore, because of its high polarity, high surface tension, high specific heat capacity and network of hydrogen bonds, water plays a significant role in many reactions.10–13 Another aspect of green chemistry is the development of reusable and heterogeneous catalysts under environmentally friendly conditions. From the viewpoint of green chemistry, good recovery and reusability of the catalyst are highly preferable. These concepts are at the center of chemical activity, and research on high selectivity is the driving force for the conception of all new catalytic processes. At present, it is well known that a heterogeneous catalyst must have three characteristics: high activity, selectivity and stability. Nanotechnologies constitute an invaluable tool in catalysis. Considerable progress has been made, but many challenges that deal with the control of the localization of active sites still exist.14–17 Arylmethylene bis-(3-hydroxy-2-cyclohexene-1-one) derivatives (tetraketones) are important substrates used as precursors in the syntheses of xanthenes and acridinediones for laser dye technology.18 These compounds have also shown potent activity as antioxidants, lipoxygenase inhibitors,19 and a new clinical class of tyrosinase inhibitors against important dermatological disorders in
|