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Oxidation Of Methyl Mercaptan And Hydrogen Sulphide In A Flow Reactor With Corona Discharge, Mohamed Ibrahim El-Khashab
Oxidation Of Methyl Mercaptan And Hydrogen Sulphide In A Flow Reactor With Corona Discharge, Mohamed Ibrahim El-Khashab
Digitized Theses
The reactions of methyl mercaptan and hydrogen sulphide with air were studied separately in a tubular flow reactor which was essentially an electrostatic precipitator of the wire-cylinder type.;The products of both reactions were identified by spectroscopic methods such as NMR, IR, and MS as well as analytical methods. The oxidation products of methyl mercaptan found were water, sulphur dioxide, and dimethyl sulphone as end products and dimethyl disulphide and dimethyl sulphide as intermediates. These intermediates reacted further by using higher values of current and/or mean residence time of gaseous mixtures through the reactor. On the other hand, the oxidation products …
Spectroscopic Studies Of Metal Binding To Metallothioneins, Annie Yiu-Chu Law
Spectroscopic Studies Of Metal Binding To Metallothioneins, Annie Yiu-Chu Law
Digitized Theses
Metallothioneins (MT) are a class of cysteine-rich proteins that bind a wide variety of metal ions. Although it has been suggested that the structure of the metal binding sites in Cd,Zn-MT involves two metal clusters (alpha and beta) which coordinate the metals through a tetrahedral arrangement of cysteine residues, considerably less information is available concerning the metal binding sites in MT containing Hg('2+) and Cu('+). In this work, absorption, circular dichroism and magnetic circular dichroism spectroscopies have been used to characterize metal binding to metallothioneins. Three species of MT (rat, guinea pig and crab) have been studied. In addition to …
The Coordination Chemistry Of Fluorinated-Alcohol Thioethers, Rene Theodoor Boere
The Coordination Chemistry Of Fluorinated-Alcohol Thioethers, Rene Theodoor Boere
Digitized Theses
The synthesis of fluorinated-alcohol thioethers of the type HOC(CF(,3))(,2)CH(,2)SR (R=Me,Ph,('t)Bu), is described. These can be deprotonated to give bidentate, uninegative hybrid ligands, denoted L('-), which contain both a hard (alkoxide) and a soft (thioether) donor site (HSAB theory). They favour complex-formation with soft, over hard metal ions: CuL(,2) (R=Me) is the only stable first- row transition metal complex accessible; PdL(,2) and PtL(,2) (R=Me,Ph,('t)Bu) are all stable. By NMR, PtL(,2) is cis, with syn and anti forms from pyramidal sulfur; PdL(,2) is a cis/trans mixture of syn- and anti-isomers. Mixed-ligand complexes of the type {lcub}ML(Cl)PPh(,3){rcub} and {lcub}ML(PR(,3))(,2){rcub}BF(,4) were also prepared, M …
Genome Organization And Expression Of Selected Potexviruses, William George Bendena
Genome Organization And Expression Of Selected Potexviruses, William George Bendena
Digitized Theses
We have used in vitro translation to analyze the protein products produced from the genomic RNAs of members of the potexvirus group, namely, papaya mosaic virus (PMV), clover yellow mosaic virus (CYMV), viola mottle virus (VMV), barrel cactus virus (BCV), and foxtail mosaic virus (FTMV). Polyacrylamide gel electrophoresis of polypeptides made in vitro from the genomic RNAs of these viruses indicated that only PMV and CYMV RNA directed the synthesis of polypeptides which have the same molecular weight and antigenic determinants as their respective coat proteins. All viral RNAs tested in vitro produced high molecular weight polypeptides. Peptide mapping of …
Metallacyclobutane Chemistry, John Thomas Burton
Metallacyclobutane Chemistry, John Thomas Burton
Digitized Theses
This thesis describes the preparation, characterisation, and reactivity of a new class of platinacyclobutane complexes, containing a hydroxyl or ester functionality. The monomeric compounds are prepared by the reaction of Zeise's dimer with the appropriate cyclopropane derivative and subsequent addition of pyridine.;Owing to the presence of the hydroxyl group, these complexes have been shown to interact with the shift reagent, Eu(fod)(,3), so as to greatly simplify their ('1)H-N.M.R. spectra. Using the results obtained from this study and the equation of Karplus, comparisons are drawn between ring conformations in the solid state and solution which indicate significant puckering of these complexes …
Kinetic Applications Of Time-Resolved Electron Paramagnetic Resonance Spectroscopy, Tak-Ming Chiu
Kinetic Applications Of Time-Resolved Electron Paramagnetic Resonance Spectroscopy, Tak-Ming Chiu
Digitized Theses
Time-Resolved Flash Photolysis Electron Paramagnetic Resonance Spectroscopy has been used to probe the early electron polarization events in two different photochemical systems: (1) acetone in 2-propanol {lcub}acetone system{rcub} and (2) di-t-butyl peroxide in 2-propanol {lcub}(t-BuO)(,2) system){rcub}. On photolysis both systems give rise to the same radical species, the acetone ketyl radicals.;It was found that the observed polarization in these two systems are markedly different, reflecting different origins. In the acetone system where geminate triplet acetone ketyl radical pairs (G pairs) are expected, the polarization is of the E/A type as predicted by the Radical Pair Mechanism (RPM). In contrast, a …
Poly(Adp-Ribose) Polymerase: Aspects Of Its Interaction With Dna, Peter Zahradka
Poly(Adp-Ribose) Polymerase: Aspects Of Its Interaction With Dna, Peter Zahradka
Digitized Theses
Poly(ADP-ribose) polymerase from calf thymus was purified to near homogeneity. The use of red-agarose resulted in a rapid purification with a high yield. Purified poly(ADP-ribose) polymerase was inhibited by 1,10-phenanthroline, a metal chelating agent, at pH < 8. This inhibition and the inhibition by other chelating agents suggested that this enzyme was a metalloprotein. Control experiments eliminated the possibility that the inhibition was due to the DNA-degrading properties of 1,10-phenanthroline. Atomic absorption spectroscopy showed the presence of one atom of zinc per protein molecule. Dialysis of the enzyme against buffers containing 1,10-phenanthroline resulted in the loss of activity and the coincidental removal of zinc from the enzyme. Initial rate kinetics showed that 1,10-phenanthroline was non-competitive with NAD('+) and competitive with DNA. The binding of DNA to the enzyme was unaffected by the inhibitor. These results suggest a metal-containing site is involved in the interaction of DNA and poly(ADP-ribose) polymerase.;Previous reports have indicated that poly(ADP-ribose) polymerase, besides modifying various chromatin proteins, also modifies itself. The studies reported here indicate that this auto-modification inhibited the enzyme. By observing the binding of poly(ADP-ribose) polymerase to the DNA it was shown that the affinity of modified poly(ADP-ribose) polymerase for DNA was decreased. Mg('2+) and histone H1 appear to activate the polymerase by increasing the affinity of the auto-modified polymerase for DNA, probably by neutralizing the negative charges on poly(ADP-ribose). The coupling of poly(ADP-ribose) glycohydrolase with the polymerase reactivated the polymerase by degrading the poly(ADP-ribose) and restoring the polymerase-DNA complex. These results provided the basis for a shuttle mechanism by which proteins could be moved on and off DNA by the actions of poly(ADP-ribose) polymerase and glycohydrolase.
Mechanisms Of Thermal And Photochemical Reactions Of Organoplatinum Complexes, Ross Henry Hill
Mechanisms Of Thermal And Photochemical Reactions Of Organoplatinum Complexes, Ross Henry Hill
Digitized Theses
This thesis describes investigations into a variety of thermal and photochemical reactions of organoplatinum complexes.;The mechanism and energetics of the reaction of tertiary phosphine ligands, L, with {lcub}Pt(,2)H(,n)Me(,3-n)((mu)-dppm)(,2){rcub}('+), (n = 2,1) (dppm = bis(diphenylphosphino)methane), have been determined. The reaction was found to occur through coordination of L followed by reductive elimination. In each case H(,2) was found to be eliminated and the platinum(I) products formed were {lcub}Pt(,2)HL((mu)-dppm)(,2){rcub}('+) and {lcub}Pt(,2)MeL((mu)-dppm)(,2){rcub}('+). The rate constants and equilibrium constants were determined at a variety of temperatures, allowing construction of a reaction coordinate energy level diagram.;The photochemically induced reductive elimination reactions of the complexes {lcub}Pt(,2)H(,3-n)Me(,n)((mu)-dppm)(,2){rcub}('+), …
Sulfonylammonium Ions: Applications In Mechanistic And Synthetic Organosulfur Chemistry, John David Lock
Sulfonylammonium Ions: Applications In Mechanistic And Synthetic Organosulfur Chemistry, John David Lock
Digitized Theses
This thesis describes the results obtained from two projects in organosulfur chemistry; both of which involve the use of sulfonylammonium ions. The two projects undertaken involved sulfenes and 3-alkoxysulfonyl trialkylpropanaminium salts ("{lcub}3{rcub}betylates").;The first project describes efforts undertaken to delineate more precisely the reaction mechanisms of sulfenes, a highly reactive species. The reaction mechanism of sulfene was studied by allowing multiexchange to occur with deuterated traps. Methanol-d was used as the trapping agent in benzene-acetonitrile and deuterium oxide as the trap in a buffered deuterium oxide-dimethoxyethane system. The investigations made use of methanesulfonyl chloride and a series of trialkyl(methylsulfonyl)ammonium fluorosulfate salts …
Oxidative Addition To Platinum(Ii) Complexes, Patrick Kevin Monaghan
Oxidative Addition To Platinum(Ii) Complexes, Patrick Kevin Monaghan
Digitized Theses
This thesis describes the oxidative addition of alcohols, water and organic halides to dimethyl(2,2-bipyridine)platinum(II) (complex (I)) and to dimethyl(1,10-phenanthroline)platinum(II) (complex (II)). The work has involved characterising the reaction products and investigating the mechanism of oxidative addition. Up to now very little mechanistic work has been done for oxidative addition at platinum(II) centres.;Complexes (I) and (II) react with methanol, ethanol and isopropanol to produce the first series of platinum(IV) alkoxides of general formula {lcub}PtMe(,2)(OR)(N N)H(,2)O{rcub}('+){lcub}OH{rcub}('-) (N N = bipy or phen; R = Me, Et, ('i)Pr). Characterisation was achieved by ('1)H nmr, ('13)C nmr and elemental analysis. In an analogous reaction …