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Title: Newer Catalytic Methodologies for Domino Synthesis of Pyran, Spriooxindole, Pyridine and Rapid Decomposition of Organic Dyes
Authors: Molla, A.
Keywords: Chemistry
Issue Date: 2015
Publisher: IIT Patna
Series/Report no.: TH-18;
Abstract: Jöns Jacob Berzelius coined the term “catalysis” (from Greek kata-, “down,” and lyein, “loosen”) in 1835 and since then this new research area gradually became one of the most promising areas of research amongst the scientific community. Catalysts play an important role both in academia and the industry. Multicomponent reactions (MCRs) are one of the most well established research topics, utilises the benefits of catalytic methodologies. Multicomponent reactions (MCRs) are a special class of tandem reactions defined as a one pot chemical reaction where three or more synthons react with each other in a cascade or sequential manner to form the desired product with utilization of most of the atoms originally present in the reacting molecules. It also allows facile and efficient entrée to library of bioactive molecules. Thus researchers practicing MCRs attempting to meet the showing demands of the pharmaceutical industry in terms of design of new drug molecules. Considering the success and contribution of MCRs toward development of bioactive molecules, use of Green Chemistry principles in MCRs is becoming a popular research topic in contemporary research. Therefore, we were motivated to explore newer catalytic methodologies such as Knoevenagel-initiated Domino reactions followed by Michael addition for the facile synthesis of highly substituted heterocyles. Catalysis also plays a major role in efficient treatment of waste water. One of the major contributors to the generation of waste water are the dyes and textile industries. One of the most challenging tasks is the removal and degradation of dyes due to their high thermal and photostability. Keeping in mind the important guidelines of the green chemistry principle: “Design chemicals and products to degrade after use; Analyze in real time to prevent pollution” we were also motivated to develop a suitable catalyst for waste water treatment. The thesis entitled “Newer catalytic methodologies for domino synthesis of pyran, spirooxindole, pyridine and rapid decomposition of organic dyes” consists of seven chapters with a focus towards the development of multicomponent reactions (MCRs) for the construction of six member heterocyclic ring compounds with diverse functionalities and rapid degradation of dyes in presence of semiconductor chalcogenides which can function both in presence and absence of light. The introductory chapter (Chapter 1) presents a general idea of miscellaneous aspects of multicomponent domino reactions in organic synthesis and photocatalytic decomposition of organic dye based on a through literature survey. The sources of chemicals and solvents, methods utilized for quantitative chemical estimations, determination of elements and details of all the equipment used for physico-chemical studies are detailed in chapter 2. Chapter 3 describes the synthesis of pyran derivatives in excellent yield employing borax as catalyst under reflux condition in ethanol as solvent via multicomponent domino reaction. Chapter 4 consists of two sections dealing with two methodologies for the domino synthesis of highly functionalized spirooxindole derivatives. The extended use of borax as catalyst for the synthesis of highly functionalized pyridines, dienes, anilines and chromeno[2,3-b]pyridine-3-carbonitrile are reported in chapter 5. Chapter 6 deals with rapid degradation of organic dyes in presence of two different chalcogenide semiconductor materials under the condition of light and dark. Knoevenagel condensation followed by Michael addition in “Domino” approach for the synthesis of highly functionalized pyran, spirooxindole, pyridine, dienes and aniline derivatives of potential synthetic and pharmacological interest was achieved in presence of catalytic quantity of borax. This protocol offers multifarious advantage such as low cost, ready availability and relatively nontoxic catalyst, wide scope of substrates, operational simplicity, and high yields of the products and avoidance of column chromatography. Moreover borax, being a naturally occurring material, soluble and capable of functioning efficiently in ethanol/water, satisfies some tenets of “green chemistry.” Boron nitride supported iron oxide network (BN@Fe3O4) was prepared through a simple one-pot synthetic method, using citric acid as a stabilizing agent. First, Fe2+ was reduced in situ by NaBH4 and then aerially oxidized to form iron oxide which was used as an active catalyst for the synthesis of spirooxindole derivatives. We have also developed a simple and green protocol for the synthesis of Ag-In-Ni-S nanocomposites and nickel sulphide nanoparticles using thioacetamide as sulphur source in water. We explored the catalytic activities of both the materials for the degradation of dyes in presence and absence of light. The synergistic effect of binary and ternary chalcogenides present in Ag-In-Ni-S nanocomoposites promotes the generation of ROS which in turn helps fast degradation of dyes under dark (12min) and visible light (Sunlight: 2min, 100W lamp: 4min). The decomposition of dyes under light and dark (day and night) are especially important in the context of waste water treatment targeting the coloured effluents of dye industry. The work embodied in the thesis satisfies several tenets of “Green Chemistry”. Contemporary importance of the chosen aspects of chemistry selected for the present research work provides a large scope of the work and much more beyond.
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