Green Synthesis Of Metal Phthalocyanine Catalyzed Heterocyclic Compounds

Phthalocyanine (Pc) and their derivatives have attracted the steady attention of researchers for a long time because of their excellent optical and electronic properties as well as their chemical, thermal, and photostability. They found their place in many different areas as pigments, dyes, photodynamic therapy, gas sensor materials, organic photovoltaics, nonlinear optics, and electrocatalysis. Metal phthalocyanines are currently being intensively studied as heterogeneous catalysts owing to their ease of synthesis, their ease of chemical modification, their higher chemical stability, their structurally resemblance to the active sites of oxidation enzymes, their economical and their sensitive to light. Furthermore, metal phthalocyanines are insoluble in common organic solvents and water, so they can be easily separated from the reaction system by filtration. Metal phthalocyanines therefore show excellent performance as heterogeneous catalysts for a variety of organic reactions, for example, oxidation, reduction, dechlorination, epoxide, aziridination, cyclopropanation, propargylation, cyanosilylation, rearrangement, and Diels-Alder reactions.A serial of metal phthalocyanines and metal nitrotetraphthalocyanines were prepared by phthalic anhydride or4-nitrophthalic anhydride, urea, metal chlorides, and ammonium molybdate under heating-microwave method, then metal phthalocyanines were supported on activated carbon in sulfuric acid. The photosensitized degradation of rhodamine B by metal tetranitrophthalocyanine showed that phthalocyanine derivatives showed catalytic activity: NO2-Pc-Ni (Ⅱ)> NO2-Pc-Fe (Ⅲ)>>NO2-Pc-Zn (Ⅱ)> NO2-Pc-Co (Ⅱ)> NO2-Pc-Mn (Ⅱ)> NO2-Pc-Cu (Ⅱ). The decomposition of H2O2by iron (Ⅲ) tetranitrophthalocyanine@activated carbon showed that40%supported catalyst showed highest activity.3,4-Dialkoxythiophenes are electron rich and their polymers have a narrow energy gap, so they have recently attracted considerable attention in the field of organic semiconducting materials. A novel, efficient decarboxylation of2,5-dicarboxy-3,4-dialkoxythiophenes was achieved in excellent yields and purities using copper (Ⅱ) phthalocyanines in water, which avoids the use of organic polar solvents, and the recovered catalyst was successfully used in subsequent reactions. Furthermore, the desired products,3,4-dialkoxythiophenes, were conveniently separated by steam distillation. This method has several advantages such as environmental friendliness, ease of manipulation, and a short reaction time. This environmentally friendly procedure represents a promising green route for the decarboxylation of these important compounds.The benzimidazole nucleus is of significant importance to medicinal chemistry. Benzimidazole derivatives exhibit significant activity against several viruses.2-Substituted benzimidazoles have been synthesized from o-phenylenediamine and aldehydes in air in95%ethanol at room temperature using iron (Ⅲ) tetranitrophthalocyanines@activated carbon as catalyst in excellent yields. The salient features of this method include a highly chemoselective, mild conditions, shorter reaction time, and easy purification.Hantzsch1,4-dihydropyridines (1,4-DHPs) are important cardiovascular drugs due to their calcium antagonistic effect. The oxidation of1,4-DHPs into the corresponding pyridines is one of the main metabolic pathways of these drugs. The1,4-dihydropyridines have been synthesized using one-pot multi-component condensation from acetoacetate, aldehydes, and ammonium acetate in ethanol-water system. Hantzsch1,4-dihydropyridines were highly chemoselective oxidative aromatizated to the corresponding pyridines in the presence of H2O2using iron(Ⅲ) nitrotetraphthalocyanines as catalyst in95%ethanol at ambient temperature.Imidazole derivatives, which usually possess diverse biological activities, play important roles as versatile building blocks for the synthesis of natural products and as therapeutic agents.2,4,5-Trisubstituted imidazoles have been synthesized using multi-component condensation from benzil, aldehydes, and ammonium acetate or1,2,4,5-tetrasubstituted imidazoles from benzil, aldehydes, ammonium acetate, and aniline in the presence of iron (Ⅲ) nitrotetraphthalocyanines as recovered catalyst in95%ethanol with good yields.