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 Degree Discipline: Chemistry
 Collection: UNT Theses and Dissertations
Quantitative Chemical Analysis of the Soils of Erath County, Texas

Quantitative Chemical Analysis of the Soils of Erath County, Texas

Date: June 1938
Creator: Barnes, Benjamin F.
Description: A chemical analysis of representative samples of Windthorst sand, Denton sand, and Denton clay has been made, and this analysis shows that their composition has a strict correlation with respect to their geological origins. The analyses of the different soils have shown the Windthorst sand to be highly deficient in all of the essential elements, whereas the Denton sand is deficient in only one; namely, phosphorus. The analysis of the Denton clay showed it to be highly fertile. From the consideration of the pH and the lime content, it has been determined to some extent what crops will grow in each of the soils.
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A Study of the Quantitative Determination of Nitrogen

A Study of the Quantitative Determination of Nitrogen

Date: June 1938
Creator: Willard, John Gordon
Description: The purpose of this paper is to investigate the Kjeldahl method of nitrogen determination.
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Structure, Energetics and Reactions of Bisketenes: An Ab Initio and Density Functional Theory Study

Structure, Energetics and Reactions of Bisketenes: An Ab Initio and Density Functional Theory Study

Date: December 1997
Creator: Palmer, Prem
Description: The effect of varying substituents on structure and energies of bisketenes was studied using ab initio methods. Effect of substituents on ring closing reaction of bisketenes to the corresponding cyclobutenediones was also studied using ab initio methods. One or two of the following substituents were used to study the effect of varying substituents: BH2, CH3, NH2, OH, F, AlH2, SiH3, PH2, SH, Cl. Studies were done at the Hartree-Fock (HF), Møller-Plesset (MP2), and Density Functional Theory (B3LYP) levels of theory using the 6-31G* basis set.
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Reduction Pathways in Cyclopentadienyl Rhenium Dicarbonyl Dibromide Deriviatives and Indenyl Rhenium Tricarbonyl: Synthesis, Structure, and Reactivity of Anionic Cyclopentadienyl Rhenium Complexes. Ring Attack vs. Metal-Halogen Exchange

Reduction Pathways in Cyclopentadienyl Rhenium Dicarbonyl Dibromide Deriviatives and Indenyl Rhenium Tricarbonyl: Synthesis, Structure, and Reactivity of Anionic Cyclopentadienyl Rhenium Complexes. Ring Attack vs. Metal-Halogen Exchange

Date: December 1989
Creator: Lee, Sang Woo, 1952-
Description: The reactions of diagonal and lateral Cp'Re(CO)2Br2 (where Cp' = n5-C5H5, n5-C5Me5) and (n5-CgH7)Re(CO)3 with reducing agents have been examined. Hydride reduction at -78 °C is observed to occur at the Cp ring in both CpRe(CO)2Br2 isomers, affording a thermally unstable [(n4 -C5Hg)Re(CO)2Br2]- complex. The product of hydride ring attack has been characterized by low-temperature IR and 1H NMR measurements in addition to 13C NOE and heteronuclear 2D NMR measurements. Reaction of lateral CpRe(CO)2Br2 with either MeLi or PhLi affords both Cp-ring attack and metalhalogen exchange, [CpRe(CO)2Br]- (1) while t-BuLi reacts exclusively via metal-halogen exchange. diag-CpRe(CO)2Br2 reacts with the above lithium reagents to yield the same metal-halogen exchange anion. Analogous reactions using diag- and lat-Cp*Re(CO)2Br2 (where Cp* = n5-CgMe5) afford only the corresponding rhenium metal-halogen exchange anion, [Cp*Re(CO)2Br] (2). The molecular structures of 1-[Li/15-Crown-5] and 2-PPP were established by X-ray crystallography. 1-[Li/15-Crown-5] crystallizes in the monoclinic space group P21 with a = 10.860(4) A, b = 13.116(5) A, c = 7.417(3) A, B = 105.26(3)0, V = 1018.7(3) A3 , and Z = 2. 2-PPP crystallizes in the orthorhombic space group Pbca with a = 20.646(5) A, b = 17.690(5) A, c = 17.553(3) A, and z = 8. Solution ...
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Thermal and Flash Photolysis Studies of Ligand-Exchange Reactions of Substituted Metal Carbonyl Complexes of Cr and Mo

Thermal and Flash Photolysis Studies of Ligand-Exchange Reactions of Substituted Metal Carbonyl Complexes of Cr and Mo

Date: May 1989
Creator: Awad, Hani H. (Hani Hanna)
Description: Thermal and flash photolysis studies of ligand-substitution reactions of cis-(pip)(L)M(CO)_4 by L' (pip = piperidine; L, L' = CO, phosphines, phosphites; M = Cr, Mo) implicate square-pyramidal [(L)M(CO)_4], in which L occupies a coordination site in the equatorial plane, as the reactive species. In chlorobenzene (= CB) solvent, the predominant species formed after flash photolysis and a steady-state intermediate for the thermal reaction is cis—[(CB)(L)M(CO)_4], for which rates of CB-dissociation increase with increasing steric demands of coordinated L. Rates of CB-dissociation from trans-[(CB)(L)M(CO)_4] intermediates, formed after photolysis but not thermally, exhibit no observable dependence on the steric properties of the coordinated L.
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Kinetics Studies of Substituted Tungsten Carbonyl Complexes

Kinetics Studies of Substituted Tungsten Carbonyl Complexes

Date: August 1989
Creator: Wang, I-Hsiung, 1950-
Description: Thermal reactions and flash photolysis are used to study the olefin bond-migration promoted by tungsten carbonyls. Substitution of piperidine (pip) by 2- allylphenyldiphenylphosphine (adpp) in the cis-(pip)(η^1- adpp)W(CO)-4 complex was investigated, and no olefin bond-migration was observed. This suggests that a vacant coordinated site adjacent to the coordinated olefin is an essential requirement for olefin bond rearrangement. The rates of olefin attack on the photogenerated coordinatively unsaturated species, cis-[(CB)(η^1-ol- P)W(CO)-4] (CB = chlorobenzene, p-ol = Ph-2P(CH-2)-3CH=CH-2; n = 1-4) were measured. Kinetics data obtained both in pure CB and in CB/cyclohexane mixtures support a dissociative mechanism in which the W-CB bond is broken in the transition state. In contrast to results observed in studies of other related systems, no olefin bond-migration is noted. This observation is attributed to P-W coordination at all stages of the reaction, which precludes formation of a reactive intermediate containing a vacant coordination site adjacent to a P-ol bond.
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Studies of Nitrogen-containing Compounds Having Pyrethroid-like Bioactivity

Studies of Nitrogen-containing Compounds Having Pyrethroid-like Bioactivity

Date: August 1989
Creator: Lee, Jimmy Jing-Ming, 1955-
Description: During recent years most of the successful developments in pyrethroids have been primarily concerned with structural or compositional variations. As a part of our continuing interest in pyrethroid insecticides, nitrogen-containing compounds having pyrethroid-like structures were synthesized. Seven prolinate compounds, N-(substituted)-phenyl-prolinates and N-carbobenzoxy-prolinates were coupled with known pyrethroid alcohols. These structural variations which "locked in" a specific conformation between the nitrogen and chiral a-carbon in the acid moiety of fluvalinate were studied to determine the influence of certain conformations on insecticidal toxicity. The toxicity data for the prolinate compounds showed intermediate mortality against nonresistant cockroaches. It was concluded that the conformation imposed by the proline ring portion of the esters was probably close to the favored conformation for interaction of fluvalinate-like pyrethroids with the insect receptor site. A second series of nitrogen-containing compounds, twenty-five carbamate esters resulting from the condensation of N-isopropyl-(substituted)-anilines and N-alkyl-(substituted)-benzylamines with appropriate pyrethroid alcohols were studied for insecticidal activity. These studies were conducted on pyrethroid-susceptible houseflies. Some of the carbamate esters exhibited high toxicity when synergized by piperonyl butoxide. For example, the toxicity ( LD 50 ) of O-a-cyano-3-phenoxyfaenzyl-N-a,a-dimethyl-4-bromo-benzyl carbamate was 0.012 ug/g, which is significantly greater than that reported for the potent pyrethroid, fenvalerate. Correlations of ...
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Thermal Reactions of Four-Membered Rings Containing Silicon or Germanium

Thermal Reactions of Four-Membered Rings Containing Silicon or Germanium

Date: December 1988
Creator: Namavari, Mohammad, 1950-
Description: The synthesis of E- and Z-1,1,2,3-tetramethylsilacyclobutanes is described. Pyrolysis of either isomer at 398.2 °C provides the same products but in different amounts: propene, E- and Z-2-butene, allylethyldimethylsilane, dimethylpropylsilane, the respective geometric isomers, 1,1,2,3,3-pentamethyl-1,3-disilacyclobutane, 1,1, l-ethyldimethyl-2,2,2-vinyldimethyl-disilane and E- and Z-1,1,2,3,3,4-hexamethyl-1,3-disilacyclobutane. Mechanisms involving di- and trimethylsilenes are described for disilane formation and rate constants of the elementary steps for the fragmentation reactions are reported. Photochemically generated dimethylsilylene in the hydrocarbon solution inserts into the cyclic Ge-C or Si-C bonds of 1,1-dimethylgerma- or silacyclobutane to produce 1-germa-2-sila- or 1,2-disilacyclopentane. The relative reactivities of 1,1-dimethylgerma- and silacyclobutanes toward the dimethylsilylene have been determined. The carbenoid resulting from the cuprous chloride catalyzed decomposition of diazomethane at 25 °C in cyclohexane reacts with 1,1-dimethylgermacyclobutane to give, surprisingly 1,1,5,5-tetramethyl-1,5-digermacyclooctane as the major product. The reactions of the carbenoid with 1,1-dimethylsilacyclobutane are described. The kinetics of gas phase thermal decomposition of 1,1-dimethylgermacyclobutane has been studied over the temperature range, 684 - 751 K at pressures near 14 Torr. The Arrhenius parameters for the formation of ethylene are k_1 (s^-1) = 10^(14.6 ± 0.3) exp (62.7 ± 2.9 kcal mol^-1/RT) and those for the formation of propene and cyclopropane are k_2 (s^-1) = 10^(14.0 ± 0.1 ) exp ...
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Intramolecular [2+2] Cycloadditions of Phenoxyketenes and Intermolecular [2+2] Cycloadditions of Aminoketenes

Intramolecular [2+2] Cycloadditions of Phenoxyketenes and Intermolecular [2+2] Cycloadditions of Aminoketenes

Date: May 1989
Creator: Gu, Yi Qi
Description: One objective of this study was to explore the intramolecular [2+2] cycloadditions of phenoxyketenes to carbonyl groups with isoflavones and benzofurans as target compounds. The other objective was to investigate the eyeloaddition reactions of rarely studied aminoketenes. The conversion of 2-(carboxyalkoxy)benzils to the corresponding phenoxyketenes leads to an intramolecular [2+2] cycloaddition to ultimately yield isoflavones and/or 3-aroylbenzofurans. The product distributions are dependent upon the substitution pattern in the original benzil acids. The initial cycloaddition products, β-lactones, are isolated in some instances while some β-lactones spontaneously underwent decarboxylation and could not be isolated. The ketene intermediate was demonstrated in the intramolecular reaction of benzil acids or ketoacids with sodium acetate and acetic anhydride. It is suggested that sodium acetate and acetic anhydride could serve as a source for the generation of ketenes directly from certain organic acids. The treatment of ketoacids with acetic anhydride and sodium acetate provides a simpler procedure to prepare benzofurans than going through the acid chloride with subsequent triethylamine dehydrochlorination to give the ketenes. N-Ary1-N-alkylaminoketenes were prepared for the first time from the corresponding glycine derivatives by using p-toluenesulfonyl chloride and triethylamine. These aminoketenes underwent in situ cycloadditions with cyclopentadiene, cycloheptene and cyclooctenes to yield only the ...
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Pyrolysis Capillary Chromatography of Refuse-Derived Fuel and Aquatic Fulvic Acids

Pyrolysis Capillary Chromatography of Refuse-Derived Fuel and Aquatic Fulvic Acids

Date: December 1989
Creator: Haj-Mahmoud, Qasem M. (Qasem Mohammed)
Description: Pyrolysis-capillary gas chromatography combined with FID, ECD and MS detection were used to characterize refuse-derived fuel and aquatic fulvic acids. Different pyrolysis methods and programs were evaluated. Pyrolysis temperatures of 700-800°C produced the strongest signal for organics present in RDF and fulvic acid. Cellulose and fatty acids pyrolyzates were identifiable by GC-MS following preparative pyrolysis fractionation. At organic chloride content of 0.023%, only three halogenated compounds were detected in the GC-MS of the fractions. None of the priority pollutants were detected at lower detection limit of 0.72 to 24 mg/ kg RDF. Selective solvent extraction improves the reproduciblities of the technique and allows the detection of polymeric structures. Pyrograms of polyvinyl chloride and regular typing paper showed some common peaks that are present in the RDF pyrogram. About 65% of the peaks in the RDF pyrogram might be of paper origin. The organic chloride content of the RDF was evaluated by ion chromatography of the trapped pyrolyzates in 2% NaOH trap and it was found to be 221 mg Cl/ kg dry RDF. Pyrolysis conditions and temperature programs for FA were systematically evaluated. Samples included purified FA, methylated FA and HPLC separated fractions. Characteristic pyrograms were developed. Profiles of benzene, ...
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