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A Direct, Biomass-Based Synthesis of Benzoic Acid: Formic Acid-Mediated Deoxygenation of the Glucose-Derived Materials Quinic Acid and Shikimic Acid

Description: An alternative biomass-based route to benzoic acid from the renewable starting materials quinic acid and shikimic acid is described. Benzoic acid is obtained selectively using a highly efficient, one-step formic acid-mediated deoxygenation method.
Date: May 3, 2010
Creator: Arceo, Elena; Ellman, Jonathan & Bergman, Robert
Partner: UNT Libraries Government Documents Department

The Electronic Spectrum of (-)-S-(pS)-2,5,3',6'-Tetrahydro-2.2-Paracyclophane-2-Carboxylic Acid

Description: A new, efficient route was used in the synthesis of [2.2]-paracyclophane-2-carboxylic acid. The acid as then resolved and the Birch reduction performed yielding one enantiomer of tetrahydro-[2.2]-paracyclophane-2-carboxylic acid. The ultraviolet spectrum of tetrahydro-[2.2]-paracyclophane- 2-carboxylic acid in isopenthane shows one absorption at 206 nm (Emax = 5,271). There are three bands observed in the circular dichroism spectrum in isopentane at 236 nm ([] = 1.8 X 104), 201 nm ([0] = -16 X 104) and a positive band indicated below 180 nm but not observed. The bands were assigned and possible reasons for the occurrence of a mr'r* transition at unexpectedly long wavelengths are discussed.
Date: May 1980
Creator: Hall, Lindsey
Partner: UNT Libraries

Chiral Steering of Molecular Organization in the Limit of Weak Adsorbate-Substrate Interactions: Enantiopure and Racemic Tartaric Acid Domains on Ag(111)

Description: Article on the chiral steering of molecular organization in the limit of weak adsorbate-substrate interactions.
Date: April 23, 2010
Creator: Santagata, Nancy M.; Lakhani, Amit M.; Davis, Bryce F.; Luo, Pengshun; Buongiorno Nardelli, Marco & Pearl, Thomas P.
Partner: UNT College of Arts and Sciences

Thermolysis of a polymer model of aromatic carboxylic acids in low-rank coal

Description: To compliment our current investigation into the role that decarboxylation of aromatic carboxylic acids plays in the low-temperature cross-linking of low-rank coals, we are investigating the thermolysis of a polymeric coal model compound to determine if the polymeric network structure of coal can alter the decarboxylation pathways. In this investigation, a bibenzylic polymer, poly-(m-xylylene-co-5-carboxy-m-xylylene), 1, was synthesized containing 2.3 carboxylic acids per 100 carbons, which is similar to that found in Zapp lignite. The pyrolysis of 1 was compared to poly-m-xylylene, 2, and the methyl ester of 1, 3, to determine if the carboxy group enhances cross-linking reactions. The major product from the pyrolysis of 1 at 375{degrees} C or 400{degrees} C for 1 h was a THF insoluble residue (60-75 wt%), while pyrolysis of 2 or the methyl ester of 1 produced only a THF soluble product. The mechanistic pathways leading to cross-linking will be discussed.
Date: March 1997
Creator: Mungall, W. S.; Britt, P. F. & Buchanan, A. C., III
Partner: UNT Libraries Government Documents Department

Approaches for regeneration of amine-carboxylic acid extracts

Description: Extraction processes based on reversible chemical complexation can be useful for separation of polar organics from dilute solution. Tertiary amines are effective extractants for the recovery of carboxylic acids from aqueous solution. The regeneration of aminecarboxylic acid extracts is an important step which strongly influences the economic viability of the separation process. Several regeneration methods are critically reviewed, and the factors that affect swing regeneration processes, including temperature-swing, diluent composition-swing and pH-swing with a volatile base are discussed. Interest in this area comes from interest in treatment of waste streams, particularly in petrochemical and fermentation manufacture.
Date: July 1, 1995
Creator: Dai, Y. & King, C.J.
Partner: UNT Libraries Government Documents Department

Fatty acyl-CoA reductase

Description: The present invention relates to bacterial enzymes, in particular to an acyl-CoA reductase and a gene encoding an acyl-CoA reductase, the amino acid and nucleic acid sequences corresponding to the reductase polypeptide and gene, respectively, and to methods of obtaining such enzymes, amino acid sequences and nucleic acid sequences. The invention also relates to the use of such sequences to provide transgenic host cells capable of producing fatty alcohols and fatty aldehydes.
Date: December 1, 1998
Creator: Reiser, Steven E. & Somerville, Chris R.
Partner: UNT Libraries Government Documents Department

High Precision Measurement of Isotope Effects on Noncovalent Host-Guest Interactions

Description: Isotope effects (IEs) are a powerful tool for examining the reactivity of, and interactions between, molecules. Recently, secondary IEs have been used to probe the nature of noncovalent interactions between guest and host molecules in supramolecular systems. While these studies can provide valuable insight into the specific interactions governing guest recognition and binding properties, IEs on noncovalent interactions are often very small and difficult to measure precisely. The Perrin group has developed an NMR titration method capable of determining ratios of equilibrium constants with remarkable precision. They have used this technique to study small, secondary equilibrium isotope effects (EIEs) on the acidity of carboxylic acids and phenols and on the basicity of amines, measuring differences down to thousandths of a pK{sub a} unit. It occurred to us that this titration method can in principle measure relative equilibrium constants for any process which is fast on the NMR timescale and for which the species under comparison are distinguishable by NMR. Here we report the application of this method to measure very small EIEs on noncovalent host-guest interactions in a supramolecular system.
Date: June 23, 2009
Creator: Mugridge, Jeffrey S.; Bergman, Robert G. & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department

SPECTROSCOPIC INVESTIGATION OF THE INHIBITORY EFFECT OF FATTYACIDS ON PHOTOSYNTHETIC SYSTEMS

Description: Fatty acids have a reversible inhibitory effect on respiration and on photosynthetic action. They investigated the influence of octanoic acid on the photosynthetic bacteria Rhodopseudomonas spheroids R-26. From the spectroscopic data they conclude that a less efficient energy transfer and decoupling of the light harvesting pigment system from the energy converting reaction center is responsible for the inhibitory effect.
Date: May 1, 1971
Creator: Steffea, Hans & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

Distribution of Fatty Acids and Triethanolamine in Synthetic Metalworking Fluid Aerosols Generated in the Laboratory and Field

Description: Metalworking fluid mists were generated in the laboratory with selected synthetic fluids by nebulization and with an air sparging apparatus. Short chain fatty acid species were determined in the vapor and particulate phase of the resulting aerosols using in-situ trimethyl silyl derivatization. Certain fatty acid species in sparger generated mists were found in the vapor phase in greater quantities relative to the particle phase, compared with the corresponding amounts determined in nebulized mists. With one metalworking fluid, the nonanoic acid vapor phase to particulate phase concentration ratio was over 14 fold higher with air sparged mists (1.0) than with the corresponding nebulized mists (0.07). The nonanoic acid vapor phase concentrations were 0.026 mg/m{sup 3} and 0.002 mg/m{sup 3} for sparged (bubbled) and nebulized mists respectively. This phenomenon was observed with mists generated from several selected synthetic metalworking fluids. This could suggest that in the work place environment, with a variety of mist generation mechanisms occurring simultaneously, significant vapor phase concentrations of certain species could exist in an environment where particulate levels are low. Vapor phase fatty acid levels could remain relatively high in an occupational setting even when mist levels are reduced with efficient air cleaning devices. Results from mist generation experiments performed in the laboratory, were compared with actual field data from a relatively clean metal machining operation. Anecdotal evidence of potential irritation by short chain fatty acids prompted a study of this industrial site. Numerous air scrubbing devices were utilized at this industrial site to reduce airborne particulates, which typically ranged from 0.05 to 0.4 mg/m{sup 3}. Comparisons were made of triethanolamine and short chain fatty acid concentrations in vapor and particulate phases measured in the laboratory and work place environment.
Date: December 31, 1997
Creator: Ilgner, R.H., Palausky, A., Jenkins, R.A.
Partner: UNT Libraries Government Documents Department

Energetics and kinetics of anaerobic aromatic and fatty acid degradation. Progress report, March 1992--June 1995

Description: Factors affecting the rate and extent of benzoate degradation by anaerobic syntrophic consortia were studied. Cocultures of a syntrophic benzoate degrader, strain SB, with a hydrogen/formate-using sulfate reducer degraded benzoate to a threshold that depended on the amount of substrate and acetate present. The benzoate threshold was not a function of the inhibition of benzoate degradation capacity by acetate or the toxicity of the undissociated form of acetate. Rather, a critical or minimal Gibb`s free energy value may exist where thermodynamic constraints preclude further benzoate degradation. A sensitive assay to detect low formate concentrations was developed to measure the formate levels when the benzoate threshold was reached. We showed that increased acetate concentrations, even when hydrogen and formate levels are low, affects the extent of benzoate degradation, implicating the importance of interspecies acetate transfer. In addition to benzoate, various saturated and unsaturated fatty acids, 2-methylbutyrate, and methyl esters of fatty acids supported growth in coculture with a hydrogen-using partner. SB is the only syntrophic bacterium known to use both benzoate and fatty acids. Phylogenetic analysis showed that SB clustered with sulfate reducers in the delta subclass of the Proteobacteria. SB grew well in coculture with Desulfoarculus baarsii, a sulfate reducer that uses formate but not hydrogen. This unequivocally shows that SB can grow by interspecies formate transfer.
Date: June 23, 1995
Creator: M.J., McInerney
Partner: UNT Libraries Government Documents Department

New Tools for the site-specific attachment of proteins to surface

Description: Protein microarrays in which proteins are immobilized to a solid surface are ideal reagents for high-throughput experiments that require very small amounts of analyte. Such protein microarrays ('protein chips') can be used very efficiently to analyze all kind of protein interactions en masse. Although a variety of methods are available for attaching proteins on solid surfaces. Most of them rely on non-specific adsorption methods or on the reaction of chemical groups within proteins (mainly, amino and carboxylic acid groups) with complementary reactive groups. In both cases the protein is attached to the surface in random orientations. The use of recombinant affinity tags addresses the orientation issue, however in most of the cases the interaction of the tags are reversible (e.g., glutathione S-transferase, maltose binding protein and poly-His) and, hence, are not stable over the course of subsequent assays or require large mediator proteins (e.g., biotin-avidin and antigen antibody). The key for the covalent attachment of a protein to a solid support with a total control over the orientation is to introduce two unique and mutually reactive groups on both the protein and the surface. The reaction between these two groups should be highly selective thus behaving like a molecular 'Velcro'.
Date: June 17, 2005
Creator: Camarero, J A; Kwon, Y & Coleman, M A
Partner: UNT Libraries Government Documents Department

Improved Processes to Remove Naphthenic Acids

Description: In the past three years, we followed the work plan as we suggested in the proposal and made every efforts to fulfill the project objectives. Based on our large amount of creative and productive work, including both of experimental and theoretic aspects, we received important technical breakthrough on naphthenic acid removal process and obtained deep insight on catalytic decarboxylation chemistry. In detail, we established an integrated methodology to serve for all of the experimental and theoretical work. Our experimental investigation results in discovery of four type effective catalysts to the reaction of decarboxylation of model carboxylic acid compounds. The adsorption experiment revealed the effectiveness of several solid materials to naphthenic acid adsorption and acidity reduction of crude oil, which can be either natural minerals or synthesized materials. The test with crude oil also received promising results, which can be potentially developed into a practical process for oil industry. The theoretical work predicted several possible catalytic decarboxylation mechanisms that would govern the decarboxylation pathways depending on the type of catalysts being used. The calculation for reaction activation energy was in good agreement with our experimental measurements.
Date: December 9, 2005
Creator: Zhang, Aihua; Ma, Qisheng; Wang, Kangshi; Tang, Yongchun & Goddard, William A.
Partner: UNT Libraries Government Documents Department

{sup 17}O NMR investigation of oxidative degradation in polymers under gamma-irradiation

Description: The {gamma}-irradiated-oxidation of pentacontane (C{sub 50}H{sub 102}) and the polymer polyisoprene was investigated as a function of oxidation level using {sup 17}O nuclear magnetic resonance (NMR) spectroscopy. It is demonstrated that by using {sup 17}O labeled O{sub 2} gas during the {gamma}-irradiation process, details about the oxidative degradation mechanisms can be directly obtained from the analysis of the {sup 17}O NMR spectra. Production of carboxylic acids is the primary oxygen-containing functionality during the oxidation of pentacontane, while ethers and alcohols are the dominant oxidation product observed for polyisoprene. The formation of ester species during the oxidation process is very minor for both materials, with water also being produced in significant amounts during the radiolytic oxidation of polyisoprene. The ability to focus on the oxidative component of the degradation process using {sup 17}O NMR spectroscopy demonstrates the selectivity of this technique over more conventional approaches.
Date: March 8, 2000
Creator: ALAM,TODD M.; CELINA,MATHIAS C.; ASSINK,ROGER A.; CLOUGH,ROGER LEE & GILLEN,KENNETH T.
Partner: UNT Libraries Government Documents Department

Structures and shear response of lipid monolayers. Progress report, August 1, 1993--January 31, 1996

Description: Of the many systems now classified as {open_quotes}soft condensed matter{close_quotes}, lipids are some of the best known and most studied. Lipids occur most commonly in membranes, but the artificially created lipid systems known as Langmuir films (on water) and Langmuir-Blodgett films (on solid substrates) are in some ways better-defined and more easily controlled systems with which to address many of the same questions. Studies of these systems have a long and distinguished history, but in the past decade there has been an explosion of activity in this area, driven by the availability of a or more powerful experimental probes but also in part by the hope of producing new structured molecular materials and devices. Today the focus of device-oriented research is shifting to self-assembled (chemisorbed) films, because it is recognized that these films are somewhat more stable under application conditions. This trend has resulted in a generally more appropriate view of Langmuir and Langmuir Blodgett films as model systems with which to study the properties of organized molecular assemblies. These films are part of a larger class that includes membranes, lamellar paraffins and liquid crystals as well as self-assembled films, but with certain experimental and conceptual advantages (such as the ease with which the density may be varied, and the tethering to a flat plane). This report describes the continued studies of the phase diagrams of Langmuir monolayers, and efforts to understand the variables that affect the structures formed. It also describes studies of the structure of a transferred monolayer, and how this evolves as further layers are added. Finally, the authors describe their studies of the mechanical response of Langmuir-Blodgett films using a small-strain torsion balance at the center of a circular trough.
Date: August 1, 1995
Creator: Dutta, P. & Ketterson, J.B.
Partner: UNT Libraries Government Documents Department

Chapter 11. Community analysis-based methods

Description: Microbial communities are each a composite of populations whose presence and relative abundance in water or other environmental samples are a direct manifestation of environmental conditions, including the introduction of microbe-rich fecal material and factors promoting persistence of the microbes therein. As shown by culture-independent methods, different animal-host fecal microbial communities appear distinctive, suggesting that their community profiles can be used to differentiate fecal samples and to potentially reveal the presence of host fecal material in environmental waters. Cross-comparisons of microbial communities from different hosts also reveal relative abundances of genetic groups that can be used to distinguish sources. In increasing order of their information richness, several community analysis methods hold promise for MST applications: phospholipid fatty acid (PLFA) analysis, denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (TRFLP), cloning/sequencing, and PhyloChip. Specific case studies involving TRFLP and PhyloChip approaches demonstrate the ability of community-based analyses of contaminated waters to confirm a diagnosis of water quality based on host-specific marker(s). The success of community-based MST for comprehensively confirming fecal sources relies extensively upon using appropriate multivariate statistical approaches. While community-based MST is still under evaluation and development as a primary diagnostic tool, results presented herein demonstrate its promise. Coupled with its inherently comprehensive ability to capture an unprecedented amount of microbiological data that is relevant to water quality, the tools for microbial community analysis are increasingly accessible, and community-based approaches have unparalleled potential for translation into rapid, perhaps real-time, monitoring platforms.
Date: May 1, 2010
Creator: Cao, Y.; Wu, C.H.; Andersen, G.L. & Holden, P.A.
Partner: UNT Libraries Government Documents Department

Nucleation and Growth of Atmospheric Particles

Description: New particle formation (NPF) in the atmospheric is a two-step process: Nucleation leads to the birth of stable nuclei that subsequently grow to sizes that can be detected and affect the atmosphere’s radiative properties. Our group is studying both of these processes. Our nucleation research is largely supported by NSF and involves measurements of neutral molecular clusters formed by nucleation with a new custom-designed mass spectrometer (the Cluster-CIMS) and measurements of nanoparticle size distributions as small as 1 nm with a new aerosol spectrometer (the DEG SMPS). These measurements are providing new insights into aspects of cluster behavior that affect nucleation rates. The U.S. DOE supports our research on nanoparticle growth rates. This research couples physical and chemical measurements of aerosol properties and behavior. The TDCIMS, which enables real-time measurements of composition for freshly nucleated particles as small as 8 nm and was developed with support from DOE, is the most important tool in this work. Our most important discoveries about processes that affect growth rates are summarized in a recent PNAS article (doi:10.1073/pnas.0912127107). In short, this work has shown that alkylammonium-carboxylate salts, formed, for example, by reactions between amines and carboxylic acids, account for 20–50% of the mass of freshly nucleated particles in locations that include Atlanta, Mexico City, Boulder, and Hyytiälä, while sulfates account for only about 10%. These newly discovered compounds help to explain the high growth rates of freshly nucleated particles that have been observed around the globe and help to explain why nucleation is an important atmospheric process, not just a scientific curiosity. Our poster will provide an overview of this work.
Date: March 15, 2010
Creator: McMurry, P.; Kuang, C.; Barsanti, K.; Eisele, F.; Friedli, H.; Scheckman, J. et al.
Partner: UNT Libraries Government Documents Department

Investigation of the role of aromatic carboxylic acids in cross-linking processes in low-rank coals

Description: In the pyrolysis and liquefaction of low-rank coals, low-temperature cross-linking reactions have been correlated with the loss of carboxyl groups and the evolution of CO{sub 2} and H{sub 2}O. It is not clearly understood how decarboxylation leads to cross-linking beyond the suggestion that decarboxylation could be a radical process that involves radical recombination or radical addition reactions. We have recently conducted a study of the pyrolysis of 1,2-(3,3{prime}-dicarboxyphenyl)ethane (1) and 1,2-(4,4{prime}-dicarboxyphenyl)ethane (2) and found that decarboxylation occurs readily between 350-425 {degrees}C with no evidence of coupling products or products representative of cross-links. We proposed that decarboxylation occurred primarily by an acid-promoted cationic pathway, and the source of acid was a second carboxylic acid. The decarboxylation of 1 and 2 was investigated in diphenyl ether and naphthalene as inert diluents. In each solvent, the rate of decarboxylation dropped by roughly a factor of 2 upon dilution from the neat liquid to ca. 0.4 mole fraction of acid, but further dilution had no effect on the rate. This could be a consequence of hydrogen bonding or an intramolecular protonation. Molecular mechanics calculations indicated that 1 and 2 can adopt an appropriate conformation for internal proton transfer from a carboxy group on one ring to the second aryl ring without a significant energy penalty. In addition, the dicarboxylic acid could internally hydrogen bond, which may further complicate the reaction mechanism. Therefore, we have conducted a study of the pyrolysis of a monocarboxybibenzyl, 1-(3-carboxyphenyl)-2-(4-biphenyl)ethane (3), to determine if decarboxylation occurs by an ionic pathway in the absence of intramolecular pathways.
Date: March 1, 1997
Creator: Eskay, T.P.; Britt, P.F. & Buchanan, A.C. III
Partner: UNT Libraries Government Documents Department

Pyrolysis of coal model compounds containing aromatic carboxylic acids: The role of carboxylic acids in cross-linking reactions in low-rank coal

Description: The pyrolysis of 1-(3-carboxyphenyl)-2(4-biphenyl)ethane (1) diluted in 10-fold excess of naphthalene has been studied at 400 {degrees}C to investigate whether decarboxylation of aromatic carboxylic acids can lead to cross-linked products. The dominant mechanism for decarboxylation was found to be an acid-promoted ionic pathway that does not lead to cross-linking. However, a small amount of cross-linked products (i.e. naphthalene grafted onto decarboxylated 1) were formed. The yields of the cross-linked products were found to be decreased in the presence of a hydrogen donor solvent, tetralin, suggesting that these products were formed by a free-radical pathway. The mechanism for the formation of cross-linked products was proposed to occur from the formation and decomposition of anhydrides of 1 during pyrolysis.
Date: June 1, 1997
Creator: Eskay, T.P.; Britt, P.F. & Buchanan, A.C. III
Partner: UNT Libraries Government Documents Department

Pyrolysis Mechanisms of Aromatic Carboxylic Acids

Description: Although decarboxylation of carboxylic acids is widely used in organic synthesis, there is limited mechanistic information on the uncatalyzed reaction pathways of aromatic carboxylic acids at 300-400 {degrees} C. The pyrolysis mechanisms of 1,2-(3,3-dicarboxyphenyl)ethane, 1,2-(4,4-dicarboxylphenyl)ethane, 1-(3-carboxyphenyl)-2-(4- biphenyl)ethane, and substituted benzoic acids have been investigated at 325-425 {degrees} C neat and diluted in an inert solvent. Decarboxylation is the dominant pyrolysis path. Arrhenius parameters, substituent effects, and deuterium isotope effects are consistent with decarboxylation by an electrophilic aromatic substitution reaction. Pyrolysis of benzoic acid in naphthalene, as a solvent, produces significant amounts of 1- and 2-phenylnaphthalenes. The mechanistic pathways for decarboxylation and arylation with be presented.
Date: December 31, 1997
Creator: Britt, P.F.; Eskay, T.P. & Buchanan, A.C. III
Partner: UNT Libraries Government Documents Department

The Effect of Coenzyme A on the Metabolic Oxidation of LabeledFatty Acids: Rate Studies, Instrumentation, and Liver Fractionation

Description: The effect of pantothenic acid deficiency on the rate of C{sup 14}O{sub 2} excretion and on distribution of radioactivity in liver fractions has been studied in rats given sodium acetate-2-C{sup 14} and sodium heptanoate-7-C{sup 14} The rate of excretion of breath C{sub 14}O has been measured by use of a method in which a sensitive ionization chamber and electrometer directly and continuously record carbon-14 excretion. The labeled fatty acids are more rapidly metabolized to C{sup 14}O{sub 2} in PAD rats than in normal rats. CoA depresses the C{sup 14}O excretion 2 in both normal and PAD rats in experiments with either labeled acid. There are differences in the oxidation of these two fatty acids, and the differences are consistent with postulated metabolic schemes. CoA increases radioactivity deposited in the fat of the liver, but does not appreciably change the radioactivity incorporated in the protein and nonsaponifiable lipid fractions.
Date: April 18, 1955
Creator: Tolbert, B.M.; Hughes, Ann M.; Kirk, Martha R. & Calvin, M.
Partner: UNT Libraries Government Documents Department