R., HARISH

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PAGE  AbstractHETEROGENEOUS TRANSITION METAL CATALYSTS FOR C-C AND C-N BOND FORMING REACTIONSThe work in the thesis has been presented in five chapters. Chapter-I describes a detailed introduction on the state of the art of heterogeneous catalysts preparation, uses and advantages as well as the disadvantages.Chapter-II describes the preparation, characterization and catalytic application of nanocrystalline magnesium oxide supported palladium catalyst (NAP-Mg-Pd0). The catalyst was synthesized by counter ion stabilization of PdCl42- on to the high surface area aerogel prepared nanocrystalline magnesium oxide followed by reduction with hydrazine hydrate (Scheme 1). The NAP-Mg-Pd0 was characterized by using FTIR, XRD, XPS, TEM, ICP-AES, UV-VIS DRS, SEM-EDX etc. NAP-Mg-Pd0 was the employed in different carbon-carbon bond forming reactions namely Heck, Suzuki, Stille, and Sonogashira coupling reactions (Scheme 2). The catalyst showed excellent reusability over several cycles. Scheme 1. Preparation of NAP-Mg-Pd0. Scheme 2. Catalytic applications of NAP-Mg-Pd0 in Heck, Suzuki, Stille, and Sonogashira reactions.Chapter-III describes the preparation, characterization and catalytic application of layered double hydroxides (LDHs) supported rhodium catalyst (LDH-Rh0). The catalyst was synthesized by grafting of Rh3+ on to the LDHs followed by reduction with molecular hydrogen at 250 °C. The thus synthesized catalyst was characterized by using different techniques such as UV-VIS DRS, XPS, XRD, TEM, SEM-EDX, TPR, ICP-AES etc. LDH-Rh0 was employed in Heck, Suzuki, and Stille coupling of aryl halides (iodo- and bromoarenes). The catalyst is easily separated by filtration and recycled with almost consistent activity. Chapter-IV describes the preparation, characterization and catalytic application of modified silica supported nanorhodium catalyst (SiO2-Rh0). The catalyst was synthesized by complexation of RhCl3 with 3-aminopropyl functionalized silica gel followed by reduction with aqueous NaBH4. SiO2-Rh0 was characterized by using ICP-AES, XPS, FTIR, XRD etc. SiO2-Rh0 was employed in the Heck-type coupling of alkenes and arylboronic acids to afford the corresponding Heck product in moderate to excellent yields (Scheme 3). SiO2-Rh0 was separated by simple filtration and reused for 5 cycles with slightly diminished activity.Scheme 3. Heck-type coupling of alkenes with arylboronic acids catalyzed by SiO2-Rh0.Chapter-V is divided into two sections. Section-A describes the preparation, characterization and catalytic activity of silica immobilized copper complexes in N-arylation of N(H)-heterocycles and benzyl amines with aryl halides and arylboronic acids (Scheme 4).Scheme 4. N-arylation of N(H)-heterocycles and benzyl amine.In Section-B, the three component coupling of aldehyde, amine and terminal alkyne catalyzed by silica immobilized copper(I) iodide was described (Scheme 5). The catalyst is easily separated by simple filtration and reused with consistent activity for several cycles.Scheme 5. Three component coupling of aldehyde, amine, and alkyne catalyzed by silica immobilized CuI.PAGE  iv

ISOLATION OF BIOACTIVE MOLECULES FROM THE ROOTS OF DECALEPIS HAMILTONI AND THEIR MODE OF ACTION

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ISOLATION OF BIOACTIVE MOLECULES FROM THE ROOTS OF DECALEPIS HAMILTONI AND THEIR MODE OF ACTION

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