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in subjects: "Alkynes"

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Synthesis of Dihydropyridines and Pyridines from Imines and Alkynes via C-H Activation

A convenient one-pot C-H alkenylation/electrocyclization/aromatization sequence has been developed for the synthesis of highly substituted pyridine derivatives from alkynes and {alpha},{beta}-unsaturated N-benzyl aldimines and ketimines that proceeds through dihydropyridine intermediates. A new class of ligands for C-H activation was developed, providing broader scope for the alkenylation step than could be achieved with previously reported ligands. Substantial information was obtained about th… more

Date: November 20, 2007

Creator: Ellman, Jonathan A.; Colby, Denise & Bergman, Robert

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Large Friction Anisotropy of a Polydiacetylene Monolayer

Friction force microscopy measurements of a polydiacetylene monolayer film reveal a 300% friction anisotropy that is correlated with the film structure. The film consists of a monolayer of the red form of N-(2-ethanol)- 10,12 pentacosadiynamide, prepared on a Langmuir trough and deposited on a mica substrate. As confirmed by atomic force microscopy and fluorescence microscopy, the monolayer consists of domains of linearly oriented conjugated backbones with pendant hydrocarbon side chains above … more

Date: May 11, 1999

Creator: Burns, A. R.; Carpick, R. W. & Sasaki, D. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Organogermanium Chemistry: Germacyclobutanes and digermane Additions to Acetylenes

This dissertation comprises two main research projects. The first project, presented in Chapter 1, involves the synthesis and thermochemistry of germacyclobutanes (germetanes). Four new germetanes (spirodigermetane, diallylgermetane, dichlorogermetane, and germacyclobutane) have been synthesized using a modified di-Grignard synthesis. Diallylgermetane is shown to be a useful starting material for obtaining other germetanes, particularly the parent germetane, germacyclobutane. The gas-phase ther… more

Date: December 12, 2003

Creator: Chubb, Andrew Michael

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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The Reactivity Patterns of Low-Coordinate Iron-Hydride Complexes

This article discusses the reactivity patterns of low-coordinate iron-hydride complexes. The authors report a survey of the reactivity of the first isolable iron-hydride complexes with a coordiination number less than 5.

Date: April 30, 2008

Creator: Yu, Ying; Sadique, Azwana R.; Smith, Jeremy M.; Dugan, Thomas R.; Cowley, Ryan E.; Brennessel, William W. et al.

Item Type: Article

Partner: UNT College of Arts and Sciences

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Calculation of Abraham Model L-Descriptor and Standard Molar Enthalpies of Vaporization for Linear C7-C14 Alkynes From Gas Chromatographic Retention Index Data

Article determines Abraham model L solute descriptors for an additional 33 linear C7-C14 alkynes based on published gas chromatographic retention indices for solutes eluted from capillary columns coated with squalane and apiezon L stationary phases.

Date: 2021

Creator: Shanmugam, Neel; Eddula, Shrika; Acree, William E. (William Eugene) & Abraham, M. H. (Michael H.)

Item Type: Article

Partner: UNT College of Science

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Photosubstitution of (fulvalene)tetracarbonyldiruthenium by alkenes and alkynes: First observation of alkyne coupling on fulvalene dimetals and synthesis of a (fulvalene)dimetallacyclopentadiene(alkene) complex

No Description Available.

Date: January 18, 2002

Creator: Chen, Ming-Chou; Eichberg, Michael J.; Vollhardt, K. Peter C.; Sercheli, Ricardo; Wasser, Ian M. & Whitener, Glenn D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Hydrogen gas getters: Susceptibility to poisoning

About 40% ({approximately}9,000) of the {approximately}23,000 transuranic (TRU) waste drums at Los Alamos National Laboratory (LANL) are presently unshippable because conservative calculations suggest that the hydrogen concentration may exceed the lower explosive limit for hydrogen. This situation extends across nearly all DOE sites holding and generating TRU waste. The incorporation of a hydrogen getter such as DEB into the waste drums (or the TRUPACT II shipping containers) could substantiall… more

Date: December 31, 1998

Creator: Mroz, E. J.; Dye, R. C.; Duke, J. R. & Weinrach, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Metallacumulenes and carbide complexes. Final performance report

We investigated many aspects of transition metal complexes of carbon-rich ligands, including cumulated transition metal carbene complexes of the types vinylidene (M=C=CR{sub 2})(M = Fe, Ru, Os, Mo, W), allenylidene (M=C=C=CR{sub 2}), and butatrienylidene (M=C=C=CR{sub 2}), as well as ``naked`` carbon ligands C{sub 1}, C{sub 2}, and C{sub 3}. In the last 3 years, we began to put some effort into studying the fullerenes. Finally, we investigated initial aspects of the coordination chemistry of th… more

Date: December 31, 1992

Creator: Selegue, J. P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Further studies on hydration of alkynes by the PtCl4-CO catalyst

Under CO atmosphere, between 80 and 120 C, a glyme solution of PtCl{sub 4} forms a carbonyl compound that promotes hydration of internal as well as terminal alkynes to give aldehyde-free ketones. The catalytic process depends strongly on the electronic and steric nature of the substrates. Part of the carbonyl functions of the catalyst can be replaced by phosphine ligands. Chiral DIOP reacts with the PtCl{sub 4}-CO compound to give a catalyst that promotes partial kinetic resolution of a racemic… more

Date: January 18, 2002

Creator: Israelsohn, Osnat; Vollhardt, K. Peter C. & Blum, Jochanan

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Ligand intermediates in metal-catalyzed reactions; Annual technical report, August 1, 1992--August 1, 1993

Achievements are reported for the following 4 areas: {pi}/{sigma} equillibria in aldehyde and ketone complexes; thermodynamic ligand binding affinities ({alpha},{beta} unsaturated organic carbonyl compounds); (a new form of coordinated carbon) an unsupported C{sub 3} chain that spans two different transition metals; and (a new form of coordinated carbon) an C{sub 3} chain that is anchored by a metal on each end and spanned by a third.

Date: August 10, 1993

Creator: Gladysz, J.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Subgap absorption in conjugated polymers

Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optic… more

Date: January 1, 1991

Creator: Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J. & Baker, G. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Transferable localized orbitals for acyclic hydrocarbons.

No Description Available.

Date: January 1, 1973

Creator: England, W B

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers. Progress report

This is a progress report on the second period of activities associated with the DOE grant to the Physics Department of the University of Utah, starting on April 1st, 1991, on photocarrier dynamics, electronic defects and morphology of conducting polymers using the photomodulation spectroscopy. During the second period of this grant we have achieved impressive results and have started new studies, to be completed during the grant continuation period of the third year. We will describe our progr… more

Date: October 8, 1991

Creator: Vardeny, Z. V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Energy Randomisation. How Much of Rotational Phase Space Is Explored? How Long Does It Take?

In applying modern theories (RRKM) of unimolecular reaction, it is necessary to decide the volume of phase space in which the energy is assumed to be randomized. The question of whether the K rotational quantum number is conserved impacts on that choice. The conceptual sequence from experimental spectra, through analysis, and interpretation in terms of K relaxation is described for ethanol and 1-butyne in the 3 micron region. The interpretation of molecular eigenstate spectra involves identific… more

Date: December 1995

Creator: Perry, D. S.; Bethardy, G. A.; Davis, M. J. & Go, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Draft test plan for hydrogen getters project

Hydrogen levels in many transuranic (TRU) waste drums are above the compliance threshold, therefore deeming the drums non-shippable to the Waste Isolation Pilot Plant (WIPP). Hydrogen getters (alkynes and dialkynes) are known to react irreversibly with hydrogen in the presence of certain catalysts. The primary purpose of this investigation is to ascertain the effectiveness of a hydrogen getter in an environment that contains gaseous compounds commonly found in the headspace of drums containing … more

Date: April 1, 1998

Creator: Mroz, G. & Weinrach, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Controlled Synthesis of Polyenes by Catalytic Methods. Progress Report, December 1, 1989--November 30, 1992

A more direct approach to polyenes by the direct polymerization of acetylenes has been achieved. We were able to show that polymerization of acetylene itself can be controlled with a well- characterized alkylidene catalyst, but only if a base such as quinuclidine is present in order to slow down the rate of propagation relative to initiation. (Quinuclidine may also stabilize vinylalkylidene intermediates formed in the reaction). Unfortunately, ``living polyenes`` were no more stable than isolat… more

Date: July 1, 1992

Creator: Schrock, R. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Harnessing the Chemistry of CO2

Our research program is broadly focused on activating CO{sub 2} through the use of organic and organometallic based catalysts. Some of our methods have centered on annulation reactions of unsaturated hydrocarbons (and carbonyl substrates) to provide a diverse array of carbocycles and heterocycles. We use a combination of catalyst discovery and optimization in conjunction with classical physical organic chemistry to elucidate the key mechanistic features of the cycloaddition reactions such that … more

Date: May 11, 2010

Creator: Louie, Janis

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Catalytic Hydration of Alkenes and Alkynes

The fifteen years of DOE support have encompassed two different projects, electron-transfer reactions of metal carbonyl anions and water-soluble organometallic complexes. Each of these is related to homogeneous catalysis and will be described in separate sections. Electron Transfer--Twenty-one manuscripts resulted from our studies of electron-transfer reactions of metal carbonyl anions and acknowledge DOE support. Construction of an infrared stopped-flow system allowed us to measure rates of re… more

Date: March 18, 2003

Creator: Atwood, Jim D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The Stereoselective Formation of Bicyclic Enamines with Bridgehead Unsaturation via Tandem C-H Bond Activation/Alkenylation/Electrocyclization

Rhodium-catalyzed intermolecular C-H activation of {alpha}, {beta}-unsaturated imines in the presence of alkynes leads to a tandem process in which coupling to the alkyne occurs at the {beta}-C-H bond of the imine, followed by electrocyclization of the resulting azatriene intermediates to give dihydropyridines (eq 1). Consideration of the intramolecular version of this overall transformation (Scheme 1) raises interesting regiochemical issues. For example in a compound such as 1, where the nitro… more

Date: December 10, 2007

Creator: Ellman, Jonathan A.; Yotphan, Sirilata & Bergman, Robert

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mixed aromatic-alkyne system on Pd surface - a first principles study

Chemistry of mixed aromatic-alkyne systems on a metal surface is of general interest in many industrial processes. We use Density Functional Theory (DFT) to investigate the chemistry of one such system, i.e., 1,4-diphenyl-butadiyne, or DPB, in contact with Pd (110) and (111) surfaces. Reaction pathways and energetics of important processes are explored, including H{sub 2} adsorption, dissociation and migration on the metal surface, DPB-metal interaction, the energetics of H uptake, and the effe… more

Date: May 10, 2005

Creator: Maiti, A; Gee, R; Maxwell, R & Saab, A

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Group 4 Metalloporphyrin diolato Complexes and Catalytic Application of Metalloporphyrins and Related Transition Metal Complexes

In this work, the first examples of group 4 metalloporphyrin 1,2-diolato complexes were synthesized through a number of strategies. In general, treatment of imido metalloporphyrin complexes, (TTP)M=NR, (M = Ti, Zr, Hf), with vicinal diols led to the formation of a series of diolato complexes. Alternatively, the chelating pinacolate complexes could be prepared by metathesis of (TTP)MCl{sub 2} (M = Ti, Hf) with disodium pinacolate. These complexes were found to undergo C-C cleavage reactions to p… more

Date: December 19, 2004

Creator: Du, Guodong

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I{sub 2}, ICl, PhSeCl, PhSCl and p-O{sub 2}NC{sub 6}H{sub 4}SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This meth… more

Date: December 19, 2004

Creator: Huang, Qinhua

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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DHS Summer Student Project Report

Tetanus and botulinum neurotoxins are among the most potent toxins known to man (Montecucco et al. al., 1995). Produced by the Clostridium tetani and Clostridium botulinum bacteria, respectively, these toxins concentrate in presynaptic axons and inhibit the release of neurotransmitters leading to paralysis and possibly death. Due to the potency of this lethal class of neurotoxins, we have undertaken a project to develop high affinity ligands that specifically bind to these toxins. Such compound… more

Date: August 19, 2005

Creator: Kawamoto, S

Item Type: Report

Partner: UNT Libraries Government Documents Department

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[Ligand intermediates in metal-catalyzed reactions]. Progress report, July 1, 1989--June 30, 1992

This report consists of sections on sigma bond complexes of alkenes, a new carbon-hydrogen bond activation reaction of alkene complexes, carbon-hydrogen bond migrations in alkylidene complexes, carbon- hydrogen bond migrations in alkyne complexes, synthesis, structure and reactivity of C{sub x} complexes, synthesis and reactivity of alcohol and ether complexes, new catalysts for the epimerization of secondary alcohols; carbon-hydrogen bond activation in alkoxide complexes, pi/sigma equilibria i… more

Date: August 1, 1992

Item Type: Report

Partner: UNT Libraries Government Documents Department