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Heterogeneous asymmetric catalysis remains as an exciting research field in chiral catalysis since the heterogeneous catalyst can be separated easily from the reaction mixture compare to conventional homogeneous catalyst. The aim of the research is to develop and investigate a novel heterogeneous asymmetric catalyst using amino acid as chiral promoter. The catalysts were synthesized by attachment of amino acids such as L-glutamic acid, L-leucine and L-phenylalanine onto the hydrophilic part of hydrolyzed octadecyltrichlorosilane (OTS). The amino acidhydrolyzed OTS materials were used as catalysts for the asymmetric hydration of epoxycyclohexene to yield two diastereoisomers, namely (1R,2R)-trans-1,2-cyclohexanediol, (1S,2S)-trans-1,2-cyclohexanediol and cis-1,2-cyclohexanediol.
The work embodied in this book comprises of brief introduction of chiral homogeneous and heterogeneous asymmetric catalysis. Research work presented in this book presents synthesis and physicochemical characterization of mesoporous materials MCM-41 and SBA-15 and used them as supports for immobilization of chiral BINOL, immobilization of chiral BINOL on mesoporous materials SBA-15 and MCF of relatively large pore size and used as active catalysts for asymmetric diethylzinc addition to aldehydes, synthesis of chiral recyclable salen based metal complexes, new chiral polymeric Zn(salen) catalyst and used as a heterogeneous catalyst in asymmetric phenylacetylene addition to carbonyls, synthesis of chiral dimeric and polymeric Mn(III) salen complexes respectively. These complexes were used as recyclable catalysts in oxidative kinetic resolution of racemic secondary alcohols.
The work embodied in this book comprises of brief introduction of chiral catalysis under the homogenous and heterogeneous reaction condition. Synthesis and characterization of mesoporous material MCM-41 and SBA-15 and used them as a support for heterogenization of chiral Mn(III) salen complexes. Dicationic MnIII Salen Complex Exchanged in the Inter-layers of Montmorillonite Clay. This homogeneous and heterogenous catalyst used as active catalysts for the synthesis of chiral epoxides of non-functionalized alkenes. The epoxide functional group is one of the most useful intermediates in organic synthesis. Epoxides are versatile products and they easily undergo stereo specific ring opening reaction to form bifunctional compounds, which are very important chiral building blocks used in the preparation of optically pure bioactive molecules.
Sodium silicate from rice husk ash (RHA) was functionalized with 3-(chloropropyl)triethoxysilane (CPTES) to give RHACCl. The chlorine in RHACCl was easily substituted with 1-butylimidazole (BIm) and 7-amino-naphthalene sulphonic acid (ANSA) to form RHABIm-Cl and RHANPSO3H. Chloride ion in RHABIm-Cl was further substituted with sulphate and phosphate ions to form RHABIm-HSO4 and RHABIm-H2PO4 respectively. RHABIm-H2PO4 showed a higher catalytic activity and selectivity than RHABIm-HSO4 in the acetalization of glycerol (Gly) to cyclic acetals. The conversion of benzaldehyde (Benz) using RHABIm-H2PO4 and RHABIm-HSO4 were determined to be 80 and 75 % respectively. The use of RHABIm-HSO4 as catalyst resulted in high selectivity towards the HMPD. RHABIm-HSO4 was reused three times with some loss of activity due to adsorbed water on the catalyst surface. The catalytic performance of RHANPSO3H was also tested in the acetalization of glycerol with benzaldehyde which gave a conversion of 72 % and 87% selectivity towards HMPD. The catalyst could be regenerated by washed with ethanol and dried at 110 °C for 24 h.
This work reports some original and significant contributions on chiral coordination complexes. Complexes of chiral amino alcohols based Schiff base ligands with biologically and catalytically important metal ions have been developed and studied with respect to their structural, spectroscopic, supramolecular and catalytic properties. The importance of chiral amino alcohol based Schiff base ligands in coordination chemistry is briefly discussed in the introduction chapter. Synthetic details and spectroscopic characterization data of some new chiral Schiff base ligands and their metal complexes are presented in chapter two. Detailed studies on a series of biologically and catalytically relevant chiral Mn(IV) complexes form the content of the third chapter. A series of interesting mixed valence multinuclear cobalt complexes of chiral amino alcohol based ligands has been described in chapter four. Studies on some chiral copper complexes highlighting their structural and supramolecular properties are presented in fifth chapter. Finally, the work is concluded giving an overall summary as the sixth chapter.
The main aim of this work is the development of synthetic routes towards amino alcohols as well as branched ?? and ??amino acids starting from achiral and chiral (racemic and optically active) isoxazolines and N-methylisoxazolinium salts. The isoxazolines were treated with a variety of Grignard reagents and organolithium complexes as C-nucleophiles. These results were comparable to the findings of analog additions to the ‘’activated’’ isoxazolines, that is, to the isoxazolinium salts. The latter react smoothly with Grignard reagents, as well as with weaker C-nucleophiles such as sodium diethyl malonate or lithium ester enolate. At the same time it was observed, that the addition proceeds with -particly- good diastereoselectivity under mild reaction conditions, leading to good yields of the corresponding substituted isoxazolidines.
A wide variety of novel materials can be prepared through the chemical modification of silica gels. In addition to their use in chromatographic separations, they have been increasingly used as catalysts in liquid phase organic reactions. The application of these materials results in viable and more environmentally friendly alternatives to traditional homogeneous catalysts. The present monograph describes the synthesis of two functionalized silica gels for highly specific separation and preconcentration of metal ions followed by their applications as sensors and as catalysts.
This review summarizes the chiral high performance liquid chromatographic (HPLC) direct methods with different class of macrocyclic antibiotics as chiral selectors. In the past few decades, these organic macromolecules have become one of the most useful chiral selectors in analytical HPLC, thin layer chromatography (TLC) and capillary electrophoresis (CE) methods and also in preparative methods. The macrocyclic glicopeptides, such as teicoplanin, vancomycin and ristocetin, seem to be the most useful selectors for the enantioseparation of compounds with primer amino groups. Especially in wild range of amino acids and proteins. In this work the physicochemical properties, the efficiency of these antibiotics and the mechanism of separation were discussed in reversed phase (RPM), polar organic and ionic mode (POM, PIM) and in normal phase system (NPM).
Direct aldol reactions have been successfully performed using aromatic aldehyde and cyclic ketone in nonpolar/polar solvent using immobilized picolylamine on zirconia as a catalyst, in a double walled three necked batch reactor. The prepared catalyst was characterized by SEM, XRD and FT-IR. FT-IR peaks reveal the presence of picolylamine on the surface of zirconia. The catalyst show excellent catalytic activity in aldol reaction of cyclohexanone with benzaldehyde in cyclohexane giving (2-hydroxy phenyl methyl cyclohexanone) (55.7% yields) in 4 hours at 80°C. Furthermore, the catalyst is recoverable by simple filtration and could be used several times without significant loss in activity. In addition the chiral amine will be anchor on the surface of zirconia for asymmetric aldol reaction in future studies.
Chemical kinetics is the systematic detailed study of the rate of chemical reactions and the factors which control and influence their progress and course. The ultimate object is to ascertain the behaviour of molecules and ions during the course of a chemical reaction and to draw a definite conclusion about their detailed mechanism i.e. the specific course which it follows. Chemical kinetics might very well be called as chemical dynamics. In kinetic investigations, a large number of factors may influence the rate of a reaction. Some of these factors are concentration of the reactants and products, temperature, dielectric constant of the reaction mixture, total ionic strength of the medium and intensity of the radiation absorbed by the reactions. There are many reactions in which orders are not simple power functions of the concentrations but fractional. The rate law can be derived for different mechanisms. The main use of rate data elucidating the reaction mechanism is in the establishment of kinetics and stoichiometry. The role of catalyst was widely recognized in modern chemical industry and have therefore been subjected to qualitative and quantitative studies.
Adibi Branched Chain Amino And Keto Acids In ?heal Th And Disease?
The search for eco-friendly corrosion inhibitor is essential for the industries where corrosion is a major problem. This book is a report of research jointly carried out by the Femi Awe and Professor Nnabuk Okon Eddy. The research was conducted to investigate the possibility of using some amino acids as inhibitors for the corrosion of mild steel in solutions of HCl. Theoretical (quantum chemical principles) and experimental(gravimetric, gasometric, thermometric and FTIR) approaches were employed in the research. The work is more of a research monograph and were conducted under the supervision and supports of eminent academicians (including Professor U. J. Ibok and Prof. E. C. Gimba). The authors found that amino acids are good corrosion inhibitors and have have also established equations using QSAR that can be used as a guide toward the synthesis of new corrosion inhibitors. Application of condensed Fukui and softness functions as well as relative nucleophilicity/electrophilicity (calculated for B3LYP(6-31G) and MP2(STO-5G) paturbations) yeilded information on the sites for electrophilic and nucleophilic attacks.