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Thermochemical and Theoretical Studies of Dimethylpyridine-2,6-dicarboxylate and Pyridine-2,3-, Pyridine-2,5-, and Pyridine-2,6-dicarboxylic Acids

Description: Article discussing thermochemical and theoretical studies of dimethylpyridine-2,6-dicarboxylate and pyridine-2,3-, pyridine-2,5- and pyridine-2,6-dicarboxylic acids.
Date: May 6, 2005
Creator: Matos, M. Agostinha R.; Morais, Victor M. F.; Silva, Maria D. M. C. Ribeiro da; Marques, Marta C. F.; Sousa, Emanuel A.; Castiñeiras, Jorge P. et al.
Partner: UNT College of Arts and Sciences

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

Description: 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 the mechanism of the reaction. This included the isolation of a C-H activated complex and its structure determination by X-ray analysis; in addition, kinetic simulations using the Copasi software were employed to determine rate constants for this transformation, implicating facile C-H oxidative addition and slow reductive elimination steps.
Date: November 20, 2007
Creator: Ellman, Jonathan A.; Colby, Denise & Bergman, Robert
Partner: UNT Libraries Government Documents Department

The Proton Nuclear Magnetic Resonance Spectra of Pyridines

Description: Report discussing the proton NMR spectra of 32 pyridines in two solvents, carbon tetrachloride and bezene-d6, are presented. The chemical-shift and differential-shift values are correlated with the substitutent position and with the solvent media. The ring protons and the protons on alkyl substituents are tabulated. The paramagnetic shift of the protons adjacent to the nitrogen is discussed, and a proposed structure for the pyridine-benzene complex that is consistent with the observed anomalous paramagnetic shift is presented. The utility of the data in the identification of pyridine compounds found in shale-oil naphtha is demonstrated.
Date: 1971
Creator: McDonald, F. R.; Decora, A. W. & Cook, G. L.
Partner: UNT Libraries Government Documents Department

Versatile assembly of p-carboxylatocalix[4]arene-O-alkyl ethers

Description: Crystallisation of lower-rim tetra-O-alkylated p-carboxylatocalix[4]arenes from pyridine results in the formation of both bi-layer and pillar type supramolecular motifs. Full alkylation at the calixarene lower rim has significant influence over the supramolecular self-assembly motif, including preclusion of pyridine guest molecules from the calixarene cavity in the solid state.
Date: July 8, 2009
Creator: Kennedy, Stuart; Teat, Simon J. & Dalgarno, Scott J.
Partner: UNT Libraries Government Documents Department

The Preparation of Pyridinium Derivatives by the Knoevenagel Condensation

Description: An attempt is made in the work described in this paper to extend the series started by Hall and Platas by means of a Knoevenagel condensation between 3-hydroxy-1,4-naphtho-quinone-2-(4-methylpyridinium) anhydride and various aromatic aldehydes giving rise to a series of unsaturated substituents on the four position of the pyridine ring.
Date: May 1955
Creator: Miller, Eugene James
Partner: UNT Libraries

THE PHOTOCHEMISTRY OF PYRIDINE N-OXIDE

Description: The authors wish to report their results on the photolysis of pyridine N-oxide in alcoholic solution. Both methanol and ethanol solutions of pyridine N-oxide were irradiated. The reaction mixture was analyzed by gas-liquid chromatography (GLC) using a 2.5% FFAP on Chrom G column and a Porapak Q column. In order to collect the products, the volume of the photolysis solution was reduced in vacuo and the resulting mixture was separated by preparative GLC.
Date: September 14, 1967
Creator: Alkaitis, Algis & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

Regulation of Pyridine Nucleotide Metabolism in Saccharomyces cerevisiae

Description: The levels of total nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), and their redox states were determined as the function of growth in S. cerevisiae. Cells growing in a medium containing 0.8% glucose exhibit two phases of exponential growth, utilizing glucose and ethanol, respectively. The NAD pool is 50% reduced during both stages of growth while the NADP pool is 67% reduced in glucose growth and 48% reduced in ethanol growth. The NAD/NADP ratio is constant during growth on glucose and a two-fold increase in the NAD/NADP ratio occurs upon exhaustion of glucose. The increased ratio is maintained during growth on ethanol. This alteration in the regulation of the relative levels of NAD and NADP may be due to a change in the regulation of NAD kinase and/or NADP phosphatase activities. These changes may be related to the redox state of the NADP pool.
Date: May 1976
Creator: Ting, Haung-yu
Partner: UNT Libraries

CARBOXYLATIONS AND DECARBOXYLATIONS

Description: A brief survey of decarboxylation reactions and carboxylation reactions that are known or presumed in biological systems will be presented. While a considerable number of amino acid decarboxylations are known, their mechanisms will not be included in the present discussion but will be reserved for a later paper in the symposium. The remaining decarboxylation reactions may be subdivided into oxidative and nonoxidative decarboxylations. In most cases, these reactions are practically irreversible except when coupled with suitable energy-yielding systems. The carboxylation reactions which are useful in the formation of carbon-carbon bonds in biological systems seem to fall into two or three groups: those which exhibit an apparent ATP requirement, and those which exhibit a reduced pyridine nucleotide requirement, and those which exhibit no apparent ATP requirement. Of the first group at least four cases, and possibly six or seven, are known, and one interpretation of them involves the preliminary formation of 'active' carbon dioxide, generally in the form of a carbonic acid-phosphoric acid anhydride. Those exhibiting no apparent ATP requirement seem to be susceptible to classifications as enol carboxylations in which the energy level of the substrate compound is high, rather than that of the carbon dioxide. There appear to be at least three examples of this latter type known, amongs them being the carboxy-dismutase reaction of ribulose diphosphate with carbon dioxide.
Date: April 21, 1959
Creator: Calvin, Melvin & Pon, Ning G.
Partner: UNT Libraries Government Documents Department

Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

Description: Palladium-catalyzed heteroannulation of 1,3-dienes with 3-iodo-2-alkenols, and 2-iodo-2-alkenols, as well as their amino analogs, affords the corresponding cyclic ethers and amines respectively. The presence of a {beta}-hydrogen in the vinylic halide results in {beta}-hydride elimination giving the corresponding alkyne. The presence of a bulky group in the {alpha}-position of the vinylic halide results in failure or reduced amounts of annulation products. A chloride source, pyridine base and electron-rich phosphine are essential for this reaction.
Date: December 19, 2004
Creator: Rozhkov, Roman Vladimirovich
Partner: UNT Libraries Government Documents Department

Shale oil value enhancement research. Quarterly report, January 1, 1996--March 31, 1996

Description: Activities during this quarter focused on (a) compound type analysis of shale oil and its extraction products, (b) thermal hydrodealkylation of the > 290{degrees}C polar fraction, and (c) economic analysis of the SPX project. At the end of this quarter, Mr. Jerry Wiser - the chief process engineer of JWBA, took a job with an equipment and engineering firm in the Salt Lake City. Jerry still maintains his contact with us as an Associate of the company. With regard to the SPX project, Jerry`s contribution included the process control and automation of various process units including the 15-stage distillation column and the continuous liquid-liquid extraction column. He also participated in data processing of the microanalysis of the complex hydrocarbon mixtures. All of the works he was involved in are fully functional and well-documented. At this transition stage, his previous duty is fulfilled by other JWBA staff. The current SPX team is well-suited for the upcoming tasks of running the PDU`s and preparing samples for introduction to potential partners and buyers. The dialog with potential industrial partners is continuing. We keep receiving inquires about our pyridine technology, including companies outside of United States. We are also preparing for presentation of a business plan before the Dawnbreaker commercialization assistance program. At the present time, although we can put together a {open_quotes}presentable{close_quotes} package, the lack of manufacturing plan and proof of market assurance (the originally proposed Phase-III work which has yet to be funded) may turn out to be critical for making this project commercial attractive.
Date: May 1, 1997
Partner: UNT Libraries Government Documents Department

Non-traditional solution routes to ferroelectric materials

Description: Non-traditional precursor solutions for production of ferroelectric thin films have been developed for PXZT (X = L, N, S), SBT, and PMN systems. For PXZT and SBT, pyridine is a key solvent, wherein, it both solubilizes and reduces the reactivity of the individual components of the solution. Further control of the final films has been obtained using novel tailor-made precursors to dictate their properties.
Date: April 1, 1997
Creator: Boyle, T.J.; Buchheit, C.D. & Al-Shareef, H.N.
Partner: UNT Libraries Government Documents Department

Alkaloid-derived molecules in low rank Argonne premium coals.

Description: Molecules that are probably derived from alkaloids have been found in the extracts of the subbituminous and lignite Argonne Premium Coals. High resolution mass spectrometry (HRMS) and liquid chromatography mass spectrometry (LCMS) have been used to characterize pyridine and supercritical extracts. The supercritical extraction used an approach that has been successful for extracting alkaloids from natural products. The first indication that there might be these natural products in coals was the large number of molecules found containing multiple nitrogen and oxygen heteroatoms. These molecules are much less abundant in bituminous coals and absent in the higher rank coals.
Date: November 30, 2000
Creator: Winans, R. E.; Tomczyk, N. A. & Hunt, J. E.
Partner: UNT Libraries Government Documents Department