UNT Libraries - Browse

ABOUT BROWSE FEED
Survey of the Solid State Conformation of Calix[4]arenes
The characteristics of seventy-six calix[4]arene crystal structures derived from the Cambridge Crystallographic Database are presented. This survey is a discussion of the inter and intramolecular effects on the solid state cavity shape and molecular recognition ability of the compounds. In addition to this survey, four new calix[4]arene crystal structures are presented. The conformational characteristics of these four calixarenes are determined by a complicated array of inter and intramolecular interactions in the crystal packing.
Interactions of Clean and Sulfur-modified Reactive Metal Surfaces with Aqueous Vapor and Liquid Environments : A Combined Ultra-high Vacuum/electrochemistry Study
The focus of this research is to explore the molecular-level interactions between reactive metal surfaces and aqueous environments by combined ultra-high vacuum/electrochemistry (UHV-EC) methodology. The objectives of this work are to understand (1) the effects of sulfate ions on the passivity of metal oxide/hydroxide surface layer, (2) the effects of sulfur-modification on the evolution of metal oxide/hydroxide surface layer, and (3) the effects of sulfur adsorbate on cation adsorption at metal surfaces.
Chemical Equilibria in Binary Solvents
Dissertation research involves development of Mobile Order Theory thermodynamic models to mathematically describe and predict the solubility, spectral properties, protonation equilibrium constants and two-phase partitioning behavior of solutes dissolved in binary solvent mixtures of analytical importance. Information gained provide a better understanding of solute-solvent and solvent-solvent interactions at the molecular level, which will facilitate the development of better chemical separation methods based upon both gas-liquid and high-performance liquid chromatography, and better analysis methods based upon complexiometric and spectroscopic methods. Dissertation research emphasizes chemical equilibria in systems containing alcohol cosolvents with the understanding that knowledge gained will be transferable to more environmentally friendly aqueous-organic solvent mixtures.
Mobile Order Theory as Applied to Polycyclic Aromatic Heterocycles
Experimental mole fraction solubilities of benzil, thianthrene, trans-stilbene, thioxanthen-9-one, diphenyl sulfone and dibenzothiophene sulfone are determined in pure noncomplexing and complexing solvents. Predicted solubility values are calculated for benzil, thianthrene, trans-stilbene and thioxanthen-9-one using expressions derived from Mobile Order theory. Large deviations between experimental and predicted solubilities in alcohol solvents exist, therefore optimized solute - solvent association constants are determined. Previously measured thianthrene solubilities in five binary alkane + cyclohexane solvent mixtures are compared with values predicted from Mobile Order theory using the measured solubility in each of the pure solvents as input parameters. The experimental mole fraction solubility of benzil in eight binary alcohol + 1-octanol solvent mixtures are also measured and compared with predicted values.
Discontinuous Thermal Expansions and Phase Transformations in Crystals at Higher Temperatures
The purpose of this investigation is to make more detailed studies of transformations. Fourteen compounds have been examined by high temperature X-ray diffraction for this purpose. The investigations have been carried out in such a way as to reveal: 1. the existence of transformations, 2. the influence of polarizability on thermal expansion, 3. the anisotropy of expansion, and 4. the discontinuity of thermal expansion.
Synthesis of Crown Ether/Ammonium Salt for Electron Transfer Study
The theoretical model of Beratan and Onuchic predicts a large attenuation of ET rates through hydrogen bonds; however, the effect of individual hydrogen bond on electron transfer reaction has not been systematically studied. The organic complexes in this study are a series of crown ether/ammonium salt, which incorporate a redox partner on each component of the complex. The dimethoxynaphthalene redox donor was attached to the crown ether and a series of ammonium salts was synthesized which bear substituted quinone and naphthoquinone acceptor. The complexes characterization and preliminary electron transfer rate measurement were completed with UV/Vis and steady-state emission spectroscopy.
Fluorination Effect on the Conformational Properties of Alkanes
A Series of fluorophores of the general formular P(CF2)nP and P(CF2)n-1CF3 has been synthesized. Copper catalyzed coupling of 1-bromopyrene and the corresponding mono and di-iodoperfluoroalkanes were used in most cases. For the n=3 dimer, a novel 1,w-perfluoroalkylation of pyrene via bis-decarboxylation of hexafluorogultaric acid was utilized. These compounds, along with suitable hydrocarbon analogs, are being used to study the flexibility of fluorocarbon chains using emission. We have found that the excimer formation for the fluorinated pyrene monomers is highly dependent on concentration and is less efficient than for pyene. Excimer formation for the fluorinated pyrene dimers is much more efficient than for the fluorocarbon monomers and is only slightly concentraion dependent. Steady-state emission spectra indicate hydrocarbon dimers-models form excimers more efficiently than the fluorinated dimers suggesting the fluorinated chains are stiffer than the hydrocarbons. We conducted the temperature-dependent studies and quantified the conformational difference.
Reactions of N-(Substituted) Phthalimides with n-Alkylamines
The initial purpose of this study was to determine if steric problems would account for the difference in the products obtained in the reaction of the N-(substituted)phthalimide with low and high molecular weight amines.
ESR Studies of Group IV Substituted Anilines
The purpose of the investigation described herein was to investigate the degree of delocalization of the unpaired electron in ion radicals formed in the oxidation process of compounds with aromatic rings connected by means of various groups and atoms not entering the ring; then, to establish the relationship of coupling constants in radical cations with substituent σ values. The parent cation radical, in which the co-planar ion was derived from N,N-dimethylaniline, was selected in order to maximize the substituent effects on coupling constants and to obtain couplings at several positions (specifically, CH3, N, and ring protons).
Oxovanadium(IV) Complexes of Substituted N-(2-Thiophenyl)Salicylideneimine
In an effort to study the spectral, magnetic, and stereochemical properties of vanadyl complexes, both a new series of vanadyl complexes derived from type (VII) ligands with subnormal magnetic moment and from type (VIII) ligands with normal magnetic moment are synthesized and characterized.
Synthesis and Study of Certain Amino Acids Containing the Pyridine Ring
This study reported herein involves the synthesis and determination of certain biological activities of 4,5-dihydroxy-2-pyridinealanine and the synthesis of 3-pyridine-N-methylalanine.
Preparation of N-Substituted Hydroxylamines from Oxaziridines
In many series of compounds, intensity of biological activity and chemical reactivity are proportional. Generally whenever a alkyl group replaces a reactive hydrogen atom, as would be the case for an N-substituted hydroxylamine as compared to hydroxylamine, the over-all biological activity of the resulting compound is lower than that of its nonalkylated analogue. Since toxicity and physiological activity are not proportional, this comparison can only suggest possible types of derivatives to prepare and test.
Synthesis of 1-Amino-2-Hydroxycyclopentanecarboxylic Acid
This investigation involved the synthesis of 1-amino-2-hydroxycyclopentanecarboxylic acid, a potential structural analog of the natural amino acids, serine and threonine. The title compound also includes the structural features present in an established antitumor agent, cycloleucine.
Kinetic Studies and Vibrational Spectra of Disubstituted Metal Carbonyls
The oxidative elimination reactions of (5-X-phen)Mo(C0)₄ (X = H, CH₃, Cl, NO₂; phen = o-phenanthroline) and (3,4,7,8-(CH₃)₄-phen)Mo(CO)₄ with mercuric chloride in acetone have been investigated. In these reactions, a carbon monoxide group is replaced by two univalent ligands, accompanied by the corresponding increase in coordination number and formal oxidation state of the central metal atom, to give products of the type, (X-phen)Mo(CO)₃(Cl)HgCl. With the exception of (3,4,7,8-(CH₃)₄-phen), the substituted o-phenanthrolines were selected so as to minimize steric differences from one substrate to another while obtaining the widest range of pKₐ of the ligand.
The Recombination Rate Coefficient of Molecular Helium Ions in a Pulsed Afterglow at 1.86 Torr
The recombination rate coefficient for molecular helium ions has been measured in a pulsed afterglow at 1.86 Torr as a function of electron temperature and electron density without making a priori assumptions about the functional dependence. The concentrations of the molecular ions and electrons were measured and the source terms for the molecular ions were included in the rate equation.
Biological Inhibitors
Four isosteric series of plant growth-regulating compounds were prepared. Using an Avena sativa coleptile assay system, derivatives in series I and IV inhibited segment elongation to a greater degree than did comparable derivatives in series II and III.
Rearrangement of Alkylhaloketene-Cyclopentadiene Adducts in Basic Solution--A New Synthesis of 2-Alkyltropones
This research is concerned with determining whether the previously reported synthesis of tropolone by the solvolysis of the dichloroketene-cyclopentadiene adduct in sodium acetate and acetic acid could be used to prepare 2-alkyltropones from the adducts of alkylhaloketenes and cyclopentadiene. The information obtained from these rearrangements could be useful in determining the mechanism of the ring expansion of halogenated ketene-cyclopentadiene adducts to tropone derivatives.
Bonding Studies in Group IV Substituted n,n-dimethylanilines
The purpose of the present work is to study the effects of the trimethylsilyl and trimethylgermyl substituents on the N,N-dimethylamino ring system. Both ground and excited state interactions were studied and their magnitudes determined. The experimental data were then used in conjunction with molecular orbital calculations to differentiate among, and determine the importance of, d-p bonding, hyperconjugation or polarization of the trimethylsilyl group on the ground and excited state bonding.
Synthesis of Ether-free Organomagnesium Compounds
At the time this work was begun, there was some confusion about the technique necessary for the successful synthesis of organomagnesium compounds in hydrocarbon solvents and without solvents. It was decided to repeat the work of Bryce-Smith and Zakharkin. Thus began the study of the synthesis of organomagnesium compounds without solvents; the study of the reaction products of these organomagnesium compounds in hydrocarbons plus 2-butanone compared to the reaction products of the corresponding etheral Grignard reagent plus 2-butanone; and a preliminary study of the nature of these organomagnesium compounds in hydrocarbon solvents.
A Quenchofluorometric Study of Polycyclic Aromatic Hydrocarbons in Molecularly Organized Media
Detection, identification and separation of polycyclic aromatic compounds in environmental samples are of extreme importance since many of these compounds are well known for their potential carcinogenic and/or mutagenic activities. Selective quenching of molecular fluorescence can be utilized effectively to analyze mixtures containing different polycyclic aromatic hydrocarbons. Molecularly organized assemblies are used widely in detection and separation of these compounds mainly because of less toxicity and enhanced solubilization capabilities associated with these media. Feasibility of using nitromethane and the alkylpyridinium cation as selective fluorescence quenching agents for discriminating between alternant versus nonalternant polycyclic aromatic hydrocarbons (PAHs) is critically examined in several molecularly organized micellar solvent media. Fluorescence quenching is used to probe the structural features in mixed micelles containing the various combinations of anionic, cationic, nonionic and zwitterionic surfactants. Experimental results provide valuable information regarding molecular interactions between the dissimilar surfactants.
Kinetics and Mechanisms of Metal Carbonyls
Pulsed laser flash photolysis with both visible and infrared detection has been applied to the study of the displacement of weakly coordinating ligands (Lw) by strongly "trapping" nucleophiles (Ls) containing either an olefinic functionality (Ls = 1-hexene, 1-decene, 1-tetradecene) or nitrogen (Ls = acetonitrile, hydrocinnamonitrile) from the photogenerated 16 electron pentacarbonylchromium (0) intermediate. 5-Chloropent-l-ene (Cl-ol), a potentially bidentate ligand, has been shown to form (ol-Cl) pentacarbonylchromium (0), in which Cl-ol is bonded to Cr via a lone pair on the chlorine, and isomerize to (Cl-ol) pentacarbonylchromium (0), in which Cl-ol is bonded to the olefinic functionality on the submillisecond time scale. This process has been studied in both the infrared and visible region employing both fluorobenzene or n-heptane as the "inert" diluent. Parallel studies employing 1-chlorobutane and 1-hexene were also evaluated and showed great similiarity with the Cl-ol system. The data supported a largely dissociative process with a possibility of a small interchange process involving the H's on the alkyl chain. Studies were also carried out for various Cr(CO)6/arene/Ls systems (arene = various alkyl or halogenated substituted benzenes). The data indicated that for both C6H5R (R=various alkyl chains) or multi-alkyl substituted arenes (i.e. o-xylene, 1,2,3-trimethylbenzene) containing an "unhindered" ring-edge, bonding to the the Cr(CO)5 moiety occurs "edge on" via a partially delocalized center of unsaturation on the ring. The data indicated that both electronic and steric properties of the arenes influence the kinetics, and that an interchange pathway takes place at least, in part, through the alkyl chains on both the arenes and "trapping" nucleophiles. Moreover, halogenated arenes bond through the lone pair on the halogen for both CI- and Br- derivatives but "edge-on" for the fluorinated arenes. Finally, in the case of arene complexes without and "unhindered" ring-edge (i.e., 1,2,3,4,5-pentamethylbenzene) bonding can occur either "edge-on" or through the ring ...
A Chemical Analysis of Soft Wheat
The purpose of this piece of research is to determine the chemical composition of soft winter wheat, and to make a comparative study of it. A study is also made concerning its possibilities as a balanced food.
Chemical Analysis of the Bottom Deposits of Artificial Lakes with Special Emphasis on Lake Dallas
This study is for the purpose of determining the chemical content of typical artificial reservoir bottom deposits.
The Chemical Analysis of the Mebane Cottonseed Kernel
The purpose of this work is to make a fairly complete chemical analysis of the Mebane 804-50 cottonseed kernel. A brief history of cotton plant and the economic value of its products are also presented.
A Chemical Analysis of the Blackeyed Pea
The purpose of this research problem is to determine the chemical composition of the blackeyed pea and to make a comparative study of the results. The value of the blackeyed pea as food, its chemical nature, and possible industrial uses are studied and recorded.
Electrochemical synthesis of CeO2 and CeO2/montmorillonite nanocomposites.
Nanocrystalline cerium oxide thin films on metal and semiconductor substrates have been fabricated with a novel electrodeposition approach - anodic oxidation. X-ray diffraction analysis indicated that as-produced cerium oxide films are characteristic face-centered cubic fluorite structure with 5 ~ 20 nm crystal sizes. X-ray photoelectron spectroscopy study probes the non-stoichiometry property of as-produced films. Raman spectroscopy and Scanning Electron Microscopy have been applied to analyze the films as well. Deposition mode, current density, reaction temperature and pH have also been investigated and the deposition condition has been optimized for preferred oriented film formation: galvanostatic deposition with current density of -0.06 mA/cm2, T > 50oC and 7 < pH < 10. Generally, potentiostatic deposition results in random structured cerium oxide films. Sintering of potentiostatic deposited cerium oxide films leads to crystal growth and reach nearly full density at 1100oC. It is demonstrated that in-air heating favors the 1:2 stoichiometry of CeO2. Nanocrystalline cerium oxide powders (4 ~ 10 nm) have been produced with anodic electrochemical synthesis. X-ray diffraction and Raman spectroscopy were employed to investigate lattice expansion phenomenon related to the nanoscale cerium oxide particles. The pH of reaction solution plays an important role in electrochemical synthesis of cerium oxide films and powder. Cyclic voltammetry and rotation disk electrode voltammetry have been used to study the reaction mechanisms. The results indicate that the film deposition and powder formation follow different reaction schemes. Ce(III)-L complexation is a reversible process, Ce3+ at medium basic pH region (7~10) is electrochemically oxidized to and then CeO2 film is deposited on the substrate. CE mechanism is suggested to be involved in the formation of films, free Ce3+ species is coordinated with OH- at high basic pH region (>10) to Ce2O3 immediately prior to electrochemically oxidation Ce2O3 to CeO2. CeO2 / montmorillonite nanocomposites were electrochemically produced. X-ray ...
Stereoisomerism of Dimethyl Muconate
The acid which is analogous to the next member of the diphenylpolyenes, 1,4-diphenylbutadiene, is muconic acid. This acid has been chosen to be investigated in an effort to isolate all the stereoisomers of a set containing more than two isomers.
Metallization and Modification of Low-k Dielectric Materials
Aluminum was deposited onto both Teflon AF and Parylene AF surfaces by chemical vapor deposition of trimethylaluminum. This work shows that similar thin film (100 Angstroms) aluminum oxide adlayers form on both polymers at the low temperature dosing conditions used in the studies. Upon anneal to room temperature and above, defluorination of the polymer surfaces increased and resulted in fluorinated aluminum oxide adlayers; the adlayers were thermally stable to the highest temperatures tested (600 K). Angle-resolved spectra showed higher levels of fluorination toward the polymer/adlayer interface region. Copper films were also deposited at low temperature onto Teflon AF using a copper hexafluoroacetylacetonate-cyclooctadiene precursor. Annealing up to 600 K resulted in the loss of precursor ligands and a shift to metallic copper. As with aluminum adlayers, some polymer defluorination and resulting metal (copper) fluoride was detected. Parylene AF and polystyrene films surfaces were modified by directly dosing with water vapor passed across a hot tungsten filament. Oxygen incorporation into polystyrene occurred exclusively at aromatic carbon sites, whereas oxygen incorporation into parylene occurred in both aromatic and aliphatic sites. Oxygen x-ray photoelectron spectra of the modified polymers were comparable, indicating that similar reactions occurred. The surface oxygenation of parylene allowed enhanced reactivity toward aluminum chemical vapor deposition. Silicon-carbon (Si-Cx) films were formed by electron beam bombardment of trimethylvinylsilane films which were adsorbed onto metal substrates at low temperatures in ultra-high vacuum. Oxygen was also added to the films by coadsorbing water before electron beam bombardment; the films were stable to more than 700 K, with increasing silicon-oxygen bond formation at elevated temperatures. Copper metal was sputter deposited in small increments onto non-oxygenated films. X-ray photoelectric spectra show three-dimensional copper growth (rather than layer-by-layer growth), indicating only weak interaction between the copper and underlying films. Annealing at elevated temperatures caused coalescence or growth ...
Reducing the Computational Cost of Ab Initio Methods
In recent years, advances in computer technology combined with new ab initio computational methods have allowed for dramatic improvement in the prediction of energetic properties. Unfortunately, even with these advances, the extensive computational cost, in terms of computer time, memory, and disk space of the sophisticated methods required to achieve chemical accuracy - defined as 1 kcal/mol from reliable experimental data effectively - limits the size of molecules [i.e. less than 10-15 non-hydrogen atoms] that can be studied. Several schemes were explored to help reduce the computational cost while still maintaining chemical accuracy. Specifically, a study was performed to assess the accuracy of ccCA to compute atomization energies, ionization potentials, electron affinities, proton affinities, and enthalpies of formation for third-row (Ga-Kr) containing molecules. Next, truncation of the correlation consistent basis sets for the hydrogen atom was examined as a possible means to reduce the computational cost of ab initio methods. It was determined that energetic properties could be extrapolated to the complete basis set (CBS) limit utilizing a series of truncated hydrogen basis sets that was within 1 kcal/mol of the extrapolation of the full correlation consistent basis sets. Basis set truncation for the hydrogen atom was then applied to ccCA in the development of two reduced basis set composite methods, ccCA(aug) and ccCA(TB). The effects that the ccCA(aug) and ccCA(TB) methods had upon enthalpies of formation and the overall percent disk space saved as compared to ccCA was examined for the hydrogen containing molecules of the G2/97 test suite. Additionally, the Weizmann-n (Wn) methods were utilized to compute the several properties for the alkali metal hydroxides as well as the ground and excited states of the alkali monoxides anion and radicals. Finally, a multi-reference variation to the correlation consistent Composite Approach [MR-ccCA] was presented and utilized in the computation ...
Metal Complexes of 2,3-Quinoxalinedithiol
A series of new planar complexes with the dianion of 2,3-quinoxalinedithiol ligand has been prepared. The complexes have been characterized from the study of their analyses, magnetic moment, conductance, polarograms, electron spin resonance spectra, and electronic spectra, and compared with the available data on the corresponding maleonitriledithiolene and toluene-3,4-dithiolene complexes.
The Crystal and Molecular Structures of Tri-(p-Fluorophenyl)-Amine and Tri-(p-Iodophenyl)-Amine
Because of the need for data on the geometry of nitrogen in arylamines, the determination of the crystal and molecular structures of tri-(p-fluorophenyl)-amine (TFPA) and tri-(p-iodophenyl)-amine (TIPA) was undertaken as the subject of this dissertation.
Some Studies Pertaining to the Biosynthesis and Metabolism of Asparagine and Lysine in Lactobacillus Arabinosus: I. B-Aspartylhydroxamic Acid: Its Action as a Feedback Inhibitor and a Repressor of Asparagine Synthetase in Lactobacillus Arabinosus II. Purification and Properties of Diaminopimelate Decarboxylase from Lactobacillus Arabinosus
That Lactobacillus arabinosus 17-5, ATCC 8014, can supply its own requirement for the amino acid, lysine, is demonstrated by the fact that the organism is capable of growth in media devoid of lysine. Since the final biosynthetic step in lysine formation in all bacteria studied to date involves the decarboxylation of meso-dlaminopimelic acid (DAP) to produce lysine, it was of interest to determine whether an enzyme catalyzing such a reaction (DAP decarboxylase) is present in L. arabinosus.
Base Effects on the Thermal Decomposition of Sec-butyllithium Solutions
The pyrolysis of sec-butyllithium in solution was studied in an attempt to understand the loss of stereo-specificity and the atypical kinetics that have been reported. Additionally, the effect of added lithium alkoxides was studied to determine their effects on the highly reactive sec-butyllithium substrate.
Amino Acid Complexes of Rhodium(III)
This thesis will explore and study rhodium, a group VIII element that has rarely been studied.
Synthesis, Characterization, and Optical Isomerism of Some Cobalt (III) Complex Compounds
This thesis investigates the synthesis, characterization, and optical isomerism of some cobalt (III) complex compounds.
Synthesis of Selected 2-imidazolines
Since Djerassi and Scholz found that 2-(aryloxy-methyl)imidazolines and their hydrochloride salts exhibit vasoconstrictive properties, the 1,2-(I) 1,3-(II) and 1,4-bis-(2-imidazolinylmethoxy) benzene (III) analogs (Fig. 1, p.2) were chosen for synthesis in order to test them for their effective vasoconstrictive characteristics and for whatever other physiological properties they might exhibit.
Preparation of 4-Amino-3-Hydrazino-5-Methyl-s-Triazole Dihydrochloride and Condensation Products
The procedure of Takimoto, Denault, and Hotta was followed in order to prepare 4-amino-3-hydrazino-5-methyl-s-triazole hydrochloride (II) and its precursor, triamino-guanidine hydrochloride (I).
Mercury-Sensitized Photochemical Reactions of Isopropyl Alcohol
This thesis discusses the mercury-sensitized photochemical reactions of isopropyl alcohol.
Ketene Carbodiimide Cycloadditions
It was proposed to study the cycloaddition of ketenes and carbodiimides in some detail. The first objective was to investigate the general applicability of the reaction as a tool for the synthetic organic chemist in the preparation of a new class of substituted β-lactams; i.e., imino-β-lactams. It was proposed for this part of the research problem to look for the intermediate, either directly or indirectly, by trapping experiments. It was further proposed to study substituent effects in the ketene and carbodiimide and also Investigate the effect of solvent polarity on the reaction rate. From these data, it was hoped that the mechanism of the cycloaddition reaction could be elucidated.
The Crystal and Molecular Structures of 8-Hydroxyquinoline-N-Oxide and 2-Hydroxymethylpyridine-N-Oxide
This dissertation looked at the crystal structure analysis of 2-hydroxymethylpyridine-N-oxide sine this compound could provide data on both substituent effects and hydrogen bonding.
The Stereochemistry and Mechanism of Alkylhaloketene-Olefin Cycloadditions
The objectives of this research problem was to employ alkylhaloketene-olefin isomer distributions to aid in understanding the stereochemistry and mechanism of alkylhaloketene-olefin cycloadditions.
Ketene Reactions: I. The Addition of Acid Chlorides to Dimethylketene ; II. The Cycloaddition of Ketenes to Carbonyl Compounds
Part I describes the addition of several acid chlorides to dimethylketene. The resulting 3-ketoacid chlorides were isolated and characterized. Part II describes the cycloaddition of several aldoketenes to chloral. The ketenes were generated in situ by dehydrohalogenation and dehalogenation of appropriately substituted acyl halides.
The Stereochemistry of the Cycloaddition of Unsymmetrical Phenyl Ketenes to Cyclopentadiene
This dissertation is a study involving the synthesis and chemistry of arylhaloketenes and cyclopentadiene cycloadducts, and a study of the cycloadduct isomer distribution was begun.
Aromatic Amino Acid Studies
Pyridine ring analogs of the aromatic amino acids phenylalanine and tyrosine were synthesized and studied in microbiological and mammalian systems.
Infrared Studies of Group VIB metal Carbonyl Derivatives
With three different proposals for the bonding in metal carbonyls, it was decided to look into the situation more thoroughly in order to see what other evidence was available to support or refute any of these ideas. It became obvious that a definite contradiction existed between the kinetic evidence of various metal carbonyls, and the concept of MC bond strengths as predicted by Cotton's theory.
Kinetics and Mechanism Study of Diphenylketene Cycloadditions
From a review of the published work in the field of cycloadditions, it is evident that further research is needed to establish the mechanism of ketene cycloadditions. This work was initiated with the intent of obtaining kinetic data which will contribute to the elucidation of the mechanism of ketene cycloadditions.
The Electrochemical Properties of the Mercury/lithium Nitrate-potassium Nitrate Eutectic Interface
The original purpose of this investigation was to attempt to apply the coulostatic method directly to a molten salt system. The inability to duplicate the reported capacity data for this system resulted in an investigation of the probable cause of this discrepancy between the data obtained by these different methods (14, 15).
Conformationally Stable Cyclohexyllithium Compounds
Organolitnium compounds have been employed in synthetic worK for many years. However only during the last decade has much progress been made in establishing the mechanistic pathways for the reactions of these compounds.
Nuclear Magnetic Resonance Spectra of Some 1,2,4-triazoles
In the work undertaken here, NMR has been used to ascertain the structure of some 1,2,4-triazoles. The investigation provides information concerning the structure of potentially tautomeric triazoles such as hydroxy- and aminotriazole. Connected with this aspect of triazole chemistry is the larger problem of mesohydric tautomerism. The present study also yields information for a comparison of substituent effects in triazoles, N-heteroaromatic substances and benzene.
High Temperature Enthalpies of the Lead Halides: Enthalpies and Entropies of Fusion
The objectives of this investigation were: 1. To establish calorimetrically the transition temperature for the orthorhombic to cubic transition exhibited by PbF₂ and to determine the enthalpy of this transition. 2. To determine if the solid-solid phase transitions claimed in the literature for PbCl₂, PbF₂, PbBr₂, and PbI₂ were of thermodynamic importance, and if so, to determine the enthalpies of transition. 3. To determine if the discontinuous thermal expansions reported by Hsu for the lead halides were of thermodynamic importance. 4. To obtain reliable heat content data for the lead halides in both the solid and liquid states.