Browsing by Subject "Ethers"
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Item Complexation of alkali metal cations by novel ionizable polyethers(Texas Tech University, 1985-08) Ndip, Grace ManyiNot availableItem Complexing agents for metal cations and for anions(Texas Tech University, 1995-08) Zheng, RenIn recent years, the selective complexation of some organic compounds with specific metal cations and anions have drawn the interest of many chemists. These compounds have been found useful in analytical, environmental and other industrial fields. For the purpose of developing new complexing agents and probing their complexation behaviors, a series of novel macrocychc polyether compoiuids has been thesized by members of the Bartsch Research Group. The complexation of crown ethers for alkali and alkaline earth metal cations will be determined by the metal picrate extraction method. Chromatographic colimans will be used to probe the anion selectivity of some new anion exchange resins. An ultrafiltration approach will be used to evaluate the complexation of heavy metals by a water-soluble polymer. A brief review of the literature for these methods follows.Item Functionalized crown ethers as ionophores in ion selective electrodes(Texas Tech University, 1986-12) Cason, Charles VictorNot availableItem Ionizable crown ethers for the separation of alkali and alkaline earth metal cations: synthesis and applications(Texas Tech University, 1983-12) Kang, Sang IhnNot availableItem Metal ion complexation by ionizable crown ethers(Texas Tech University, 1984-08) Stewart, Louis EdwardNot availableItem Reactions of transition metal complexes with crown ethers(Texas Tech University, 1978-08) Nordyke, Mark DwightNot availableItem Some studies of syntheses and reactions of silicon-functionalized silyl enol ethers(Texas Tech University, 1989-12) Obeyesekere, Nihal U.One goal of this research project was to develop a synthesis of silyl enol ethers bearing a stereogenic silicon atom and to study the stereochemical outcome of chemical reactions of such silyl enol ethers. We envisioned that the diastereomers of an alkoxysilyl enol ether bearing a chiral alkoxy group and stereogenic at die silicon atom could be separated to yield enantiomerically pure chiral silyl enol ethers. Very few studies have been published on the effects of chiral silicon atoms upon the stereochemical outcomes of reactions of silanes. We envisioned that it was reasonable to expect the chirality on the silicon atom in a chiral silyl enol ether to influence, stericaUy, the approach of a reagent engaging with one face versus the other of the alkenyloxy ligand's double bond. To explore this possibility we studied the aldol reaction in the presence of Lewis acids, epoxidation reactions with meta-chloroperbenzoic acid (mcpba), cyclopropanation of the 16 enoxy ligand, halogenation of the enoxy ligand in the presence of N-bromosuccinimide, and reduction of the enoxy ligand. Another goal of this research was to study tiie effects of ligands attached to silicon upon the 6-endo-ttig radical cyclization of 2-IoroethylsiIyl enol ethers. As discussed above, the majority of observed free radical cyclizations feature the 5-exo-trig cyclization of a radical center 5-to an alkene to form five-membered carbocyclic or heterocyclic rings. The alternative 6-endo-trig mode of cyclization has been encountered less often, especially when the radical center is a carbon atom.41 The net conversion of 6-chloro-3-oxa-4-siIa-lhexenes to 1-oxa -2-silacyclohexanes is unprecedented and holds a great promise as a general means for extending carbon chains selectively and under mild conditions.Item Synthesis and applications of functionalized crown ethers(Texas Tech University, 1983-08) Liu, YungNot availableItem Synthesis and metal ion complexation of synthetic ionophores(Texas Tech University, 1985-12) Babb, David AlanThe use of synthetic ionophores in both academic and industrial settings continues to increase. Growth in this field of chemistry has created a need for ionophores with pendant groups which allow for further chemical elaboration. This dissertation treats the synthesis of such ionophores. Crown ethers (macrocyclic polyethers) and cryptands (macrobicyclic polyethers) which bear hydroxymethyl functions are prepared from benzyl-protected and allyl-protected precursors, respectively. Crown ethers containing ionizable chromogenic subunits are synthesized from benzocrown ether and hydroxymethylcrown ether starting materials in high yields. Neutral fluorogenic crown ethers are obtained in two steps from commercially-available starting materials. A series of novel bis-crown ethers results from condensation of diacid chlorides with hydroxy-16-crown-5 compounds. Several bis-crown ethers are tested for their ability to complex the alkali metal cations by the picrate extraction method. Results indicate that the formation of 2:1 (crown:cation) complexes with potassium ion may be promoted by linking two oxymethyl-15-crown-5 units ortho on an aryl ring. A broad spectrum of small-ring four-oxygen crown ethers are tested by the same method for their ability to extract lithium ion. Results indicate that the 14-crown-4 ring size is the best suited in extraction capacity and selectivity for the complexation of lithium. Chloroform solutions of the ionizable chromogenic crown ethers are tested for their response upon contact with aqueous solutions of the alkali metal hydroxides. It is determined that the l-amino-2,4-dinitro-6-trifluoromethylbenzene chromophore is the best suited for incorporation into chromogenic crown ethers because of its acidity, high extinction coefficient and well-resolved spectral shift upon ionization.Item Synthesis and spectral studies of lariat ethers(Texas Tech University, 1999-05) Johnson, Russell JamesA series of highly lipophilic lariat ether esters based on 5>7w-dibenzo-16-crown-5 were synthesized for evaluation in ISFET (ion selective field effect transistor) electodes Both the substituent geminal to the functional side arm and the 0-alkyl group of the ester were varied. A series of new N-(X)sulfonyl lariat ether carboxamides and their acid precursors based on 5>7w-dibenzo-16-crown-5 were synthesized for studies of the solvent extraction of alkali metal cations and their transport across polymeric inclusion membranes. These lariat ethers contain a 1-alkynyl group of varying length geminal to the functional side arm. The N-(X)sulfonyl carboxamides contain various electron-withdrawing and electron-donating X groups to "tune" the acidity of the proton-ionizable side arm. IR and *H NMR spectra of the new jrv7w-dibenzo-16-crown-5 compounds were evaluated to obtain further information about bond characters, conformations, and chemical environments of diastereotopic methylene protons in solution.Item Synthesis of crown ether-containing polymers and functionalized crown ethers(Texas Tech University, 1985-05) Son, ByungkiNot availableItem Synthesis of functionalized crown ethers and cation complexation by crown ethers(Texas Tech University, 1983-08) Heo, Gwi SukSeveral crown ethers with pendant ionizable groups such as carboxylic and phosphonic groups were synthesized from corresponding hydroxy crown ethers. Efficient and inexpensive synthetic methods were developed to produce diphenols directly from catechol. Facile syntheses of hydroxy crown ethers were achieved by the reaction of epichlorohydrin with a diphenol in alkaline aqueous media. These hydroxy crown ether provided a convenient route to ionizable crown ethers with pendant carboxylic acid groups. Various crown ether carboxylic acids with different crown ether cavity sizes and different "arm" length connecting the ionizable group to the crown ether framework were prepared. Synthetic pathways have been established for the preparation of a crown ether phosphonic acid which has a more acidic ionizable group compared with crown ether carboxylic acids. Shaking concentrated aqueous acids with methylene chloride solutions of 18-crown-6 or 12-crown-4 produced stable, solid, nonhygroscopic hydronium ion-crown ether complexes. The complexes were characterized by elemental analysis, proton NMR spectroscopy and infrared spectroscopy. The effects of polyether and anion variation upon the stoichiometry and properties of resultant hydronium ion-crown ether complexes were examined. From nitric acid and 18-crown-6, a complex composed of two nitric acid monohydrate species and one molecule of 18-crown-6 was isolated. Interaction of NOBF4 and NOPF5 with 18-crown-6, 15-crown-5, and 12-crown-4 in dichloromethane, acetonitrile and nitromethane were probed by a combination of proton magnetic resonance spectroscopy, infrared spectroscopy and conductance measurements. The stoichiometries of the crown ether-nitrosonium salt complexes were one mole of 18-crown-6 per mole of nitrosonium salt and two moles of 12-crown-4 per mole of nitrosonium salt in all solvents. For 15-crown-5, the one-to-one stoichiometry observed in acetonitrile and nitromethane changed to two moles of crown ether per mole of nitrosonium salt in dichloromethane. The nature of these complexes is discussed.Item Synthesis of lipophilic monoaza crown carboxylic acids(Texas Tech University, 1985-05) Boss, Hollis JosephNot availableItem Synthesis of macrocyclic azapolyethers(Texas Tech University, 1984-05) Nabulsi, Nabeel Abdul RaoufNot availableItem Synthesis of mono-and diazadibenzo crown ethers with ionizable pendant groups(Texas Tech University, 1988-08) Hallman, Johnny L.NOT AVAILABLE