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Articles 211 - 240 of 285
Full-Text Articles in Chemistry
Spectroscopic Studies Of Tris (2,2'-Bipyridine)- And Tris (I, 10-Phenanthroline) Iron (Ii), -Ruthenium (Ii), And -Osmium (Ii), Sonia Lee Sabath
Spectroscopic Studies Of Tris (2,2'-Bipyridine)- And Tris (I, 10-Phenanthroline) Iron (Ii), -Ruthenium (Ii), And -Osmium (Ii), Sonia Lee Sabath
Chemistry and Chemical Biology ETDs
The tris(2,2'-bipyridine)- and tris(l,10-phenanthroline) complexes of iron(II), ruthenium(II), and osmium(II) were synthesized, purified, and characterized by analyses. The solution absorption spectra of the compounds were measured both in the ultraviolet and visible regions. The observed ultraviolet absorption bands of the ruthenium and osmium complexes were assigned entirely to transitions, the prominent bands being assigned to ligand (perturbed) transitions by comparison with the published assignments of the corresponding bands in analogous iron complexes. The visible absorption spectra for iron(II) and ruthenium(II) complexes were attributed entirely to singlet-singlet charge transfer transitions. The strong visible absorption bands of osmium(II) complexes were also assigned …
The Synthesis And Evaluation Of Some 2-Arylindenes And 2-Aryl-3h-Benz[E]Indenes As Liquid Scintillation Solutes, James Leslie Schornick
The Synthesis And Evaluation Of Some 2-Arylindenes And 2-Aryl-3h-Benz[E]Indenes As Liquid Scintillation Solutes, James Leslie Schornick
Chemistry and Chemical Biology ETDs
A scintillator, in the chemical sense, is a system which can convert radioactive particle energy to visible and near ultraviolet photon energy. A phenomenon related to scintillation is fluorescence. The difference between scintillation and fluorescence is the source of excitation energy. In the case of scintillation, the exciting energy comes from radioactive particles, while in fluorescence, the exciting energy comes from ultraviolet light.
Energy Migration In Rare Earth Complexes, John Jerome Freeman
Energy Migration In Rare Earth Complexes, John Jerome Freeman
Chemistry and Chemical Biology ETDs
Complexes of trivalent samarium, europium, terbium, and dysprosium were prepared for investigations of the luminescence properties of complexed rare earth ions. Rare earth chilates derived from benzoylacetone, dibenzoylmethane, and acetylacetone; rare earth chlorides solvated with water and deuterium oxide; and rare earth oxides dissolved in sodium metaphosphate glasses were synthesized for these studies.
Radiochemical Studies: Isotopic Exchange Reactions, Solvent Effects, Preparation And Properties Of Carrier-Free Amalgams, Hans L. Hamster
Radiochemical Studies: Isotopic Exchange Reactions, Solvent Effects, Preparation And Properties Of Carrier-Free Amalgams, Hans L. Hamster
Chemistry and Chemical Biology ETDs
The work described in this section is concerned with the kinetics of an SN2 reaction, the isotopic exchange reaction between iodide ions and p-nitrobenzyl iodide, carried out in an aprotic solvent, acetone, in the presence of various substituted phenols and anisole. This reaction was carried out at concentration of potassium iodide low enough to insure the absence of ion pairs.
An Investigation Of Steric Inhibition Of Resonance In Liquid Scintillators, Richard L. Taber
An Investigation Of Steric Inhibition Of Resonance In Liquid Scintillators, Richard L. Taber
Chemistry and Chemical Biology ETDs
It is well known that the replacement of two or more of the ortho hydrogen atoms in the benzene rings of biphenyl by lager atoms or groups hinders the rotation about the l.l'-carbon single bond in the biphenyl system. If the groups are so large that they are unable to pass each other upon rotation of the l,l'-bond, then the two benzene rings are forced to assume a non-planar configuration.
Self-Diffusion In Single-Crystal Tungsten And Diffusion Of Rhenium Tracer In Single-Crystal Tungsten, Robert L. Andelin
Self-Diffusion In Single-Crystal Tungsten And Diffusion Of Rhenium Tracer In Single-Crystal Tungsten, Robert L. Andelin
Chemistry and Chemical Biology ETDs
Self-diffusion in single-crystal tungsten and diffusion of rhenium tracer in single-crystal tungsten have been measured over the temperature range 2660°C to 3230°C by the direct sectioning technique. The initial radioactive layer of tungsten and rhenium tracers was produced on the diffusion samples by bombardment with 9.0-MeV deutrons. It was shown that the initial radioactive layer satisfactorily approximated the boundary-condition requirements of the one-dimensional diffusion equation. The tracers observed in determining the diffusion coefficients were W185, Re183, and Re184. Diffusion heating of the samples in high vacuum was accomplished by an induction-heating arrangement which included …
The Kinetics Of The Hydrolysis Of Some 2-Imidazolines, Bobby G. Harnsberger
The Kinetics Of The Hydrolysis Of Some 2-Imidazolines, Bobby G. Harnsberger
Chemistry and Chemical Biology ETDs
In recent years, 2-imidazolines have become important industrially. Possible applications include uses as drugs, fungicides, emulsifying agents, demulsifying agents, corrosion inhibitors, fuel oil additives and gasoline additives.
The Analysis Of Seed Oils Of Six Tropical Plant Species By Gas Chromatography, Justin C. Hamer
The Analysis Of Seed Oils Of Six Tropical Plant Species By Gas Chromatography, Justin C. Hamer
Chemistry and Chemical Biology ETDs
Several factors influenced the choice of tropical plant seeds studied in this research. Among these factors were: (1) an early interest in the chemistry of natural products; (2) the legends surrounding the use of certain plants by native herb "doctors," and (3) the ready availability of the materials at the beginning of this investigation, which was started in Cuba.
A Spectroscopic Study Of Some Rare Earth Complexes, Richard M. Alire
A Spectroscopic Study Of Some Rare Earth Complexes, Richard M. Alire
Chemistry and Chemical Biology ETDs
The phenomenon of intramolecular energy transfer was studied using anthranilate, 8-hydroxyquinolate, 2-methyl-8-hydroxyquinolate, and salicylaldehyde rare earth chelates. Line emission characteristic of the rare earth ion was observed whenever the lowest triplet (measured) of the complex was higher in energy than the emitting (resonance) level of the rare earth trivalent ion. The path of energy transfer from the organic portion of the chelate to the rare earth ion was verified as going via the lowest or a nearby triplet state of the complex. Relative quantum yield measurements were made on the anthranilate rare earth series using a photographic method. Gadolinium anthranilate …
High Temperature Vaporization Behavior And Thermodynamic Properties Of Hafnium Diboride, Milton C. Krupka
High Temperature Vaporization Behavior And Thermodynamic Properties Of Hafnium Diboride, Milton C. Krupka
Chemistry and Chemical Biology ETDs
Vaporization of hafnium diboride has been studied in a tungsten effusion cell over the temperature range 2175°K. to 2500°K. A low-melting eutectic at 2520°K. prevented the use of the effusion cell technique at higher temperatures. An ultra-high vacuum apparatus, capable of producing vacuums of the order of 1 x 10-12 atm. or better and within which the final series of vapor pressure measurements was made, was designed and constructed during the course of this study. The effect of a high background pressure in producing species more volatile than the ones under investigation was considered to have been reduced to …
The Kinetics Of The Exchange Of Chlorine Atoms Between Hydrogen Chloride And Benzyl Chlorides, Warren Bruce
The Kinetics Of The Exchange Of Chlorine Atoms Between Hydrogen Chloride And Benzyl Chlorides, Warren Bruce
Chemistry and Chemical Biology ETDs
The study of the rates of chemical reactions in solutions has received a great deal of attention, primarily because of the relative ease with which such investigations can be persued; however, the great number of publications can never obscure the truth that a rigorous treatment of molecular processes in solutions is not available. The approach to the problem has been through extensions of theories which have their origins in descriptions of gaseous systems, and, with few exceptions, these extensions are firmly grounded on the techniques of classical thermodynamics. Hopefully, future advances in the calculation of the partition functions of molecules …
The Synthesis And Medicinal Chemical Study Of Some Pyridazones, Winnifred M. Osner
The Synthesis And Medicinal Chemical Study Of Some Pyridazones, Winnifred M. Osner
Chemistry and Chemical Biology ETDs
An examination of the literature revealed that the majority of pyridazines prepared were substituted in the three and six positions. Therefore, it appeared appropriate to prepare four and five substituted pyridazines.
An Investigation Of The Isotopic Exchange Of Arsenic Atoms Between Arsenic(Iii) And Arsenic(V) In Aqueous Hydrochloric Acid Solutions, Lewis L. Anderson
An Investigation Of The Isotopic Exchange Of Arsenic Atoms Between Arsenic(Iii) And Arsenic(V) In Aqueous Hydrochloric Acid Solutions, Lewis L. Anderson
Chemistry and Chemical Biology ETDs
An isotopic exchange reaction is a chemical reaction in which atoms of a given element interchange between two or more chemical forms of the element. A homogeneous stable system is one in which all reactants are in chemical equilibrium and distributed uniformly throughout a single phase. An example of isotopic exchange is the interchange of iodine atoms between iodide ions and ethyl iodide, where the asterisk indicates radioactive atoms of iodine.
Phase Equilibria In Fused Salt Systems: Binary Systems Of Plutonium(Iii) Chloride With The Chlorides Of Magnesium, Calcium Strontium, And Barium, Karl W. R. Johnson
Phase Equilibria In Fused Salt Systems: Binary Systems Of Plutonium(Iii) Chloride With The Chlorides Of Magnesium, Calcium Strontium, And Barium, Karl W. R. Johnson
Chemistry and Chemical Biology ETDs
Fused salt systems containing oxides have received the most attention to date, because of their occurrence in minerals and ores and their application to ceramics. The next most widely studied of group of compounds are the metal halides, particularly the metal chlorides. Despite the fact that many of the metal chlorides are hygroscopic, the salts lend themselves to experimentation because a large majority undergo stable solid-liquid transformations below 1000 degrees C, are generally ionic, and are relatively non-corrosive.
Experimental Studies Of The Visible Absorption Spectrum Of Titanium (Iii) Acetylacetonate In Solutions And Rigid Glasses, Arthur L. Langhorst Jr.
Experimental Studies Of The Visible Absorption Spectrum Of Titanium (Iii) Acetylacetonate In Solutions And Rigid Glasses, Arthur L. Langhorst Jr.
Chemistry and Chemical Biology ETDs
Titanium (III) acetylacetonate was synthesized and the visible absorption spectrum was measured. A prominent absorption band, ymax at approximately 6000 was found with molar absorption coefficient of ~1000. The spectrum was investigated at temperatures ranging from 25 degrees C to 77 degrees K. At 7 7 degrees K the band was resolved into five well defined peaks at 4750, 5100, 5520, 5950 and 6460. An apparatus for obtaining spectrophotometric measurements of solution and rigid glasses was designed and fabricated.
The Synthesis Of Potential Antitumor Compounds, Duane L. Aldous
The Synthesis Of Potential Antitumor Compounds, Duane L. Aldous
Chemistry and Chemical Biology ETDs
The antitumor activity found in such ring systems as the purine, pyrazolo [3,4-d] pyrimidine, and the 8-azapurine prompted the preparation of the imidazo [4,5-d] pyridazine ring system. Castle and Seese were one of the first to study this ring system. 4-Aminoimidazo[4,5-d]pyridazine possessed some anitumor activity. This antitumor activity suggested the preparation of the 4,7-disubstituted-aminoimidazo{4,5-d]pyridazines reported here. The antileukemic activity reported for 6-purinethiol led to the synthesis of several 4- and/or 7-mono-and disubstitutedthioimidazo[4,5-d]pyridazines.
Spectroscopic Studies Of The Luminescences Of Rare Earth Chelates, Ruth Elaine Whan
Spectroscopic Studies Of The Luminescences Of Rare Earth Chelates, Ruth Elaine Whan
Chemistry and Chemical Biology ETDs
A variety of lanthanide chelates were prepared for preliminary luminescence studies under excitation by ultraviolet light. From these, chelates of benzoylacetone, dibenzoylmethane, tribenzoylmethane, and 8-hydroxyquinoline were selected for more extensive investigation. Energies of the lowest excited singlet and triplet states of the chelates were determined. Average values of 24,500 cm-1 and 20,500 cm-1 respectively were obtained for the dibenzoylmethides and 24,400 cm-1 and 21,450 cm-1 for the benzoylacetonates. Only small variations of a few hundred wavenumbers in the positions of the excited states were found as the chelated ion was varied. This investigation in conjunction with …
The Dilute Solution Chemistry Of Antimony, Kent H. Jones
The Dilute Solution Chemistry Of Antimony, Kent H. Jones
Chemistry and Chemical Biology ETDs
Investigation of the chemistry of the elements by conventional methods is generally limited to concentrations on the order of 10-5 M or higher. The discovery of radio-activity opened new fields in chemistry among which is the obtaining of information concerning chemical behavior of elements at very low concentrations. For many years after the initial discovery of radioactivity in 1896 by Becquerel, the study of low-concentration chemistry was limited to about ten naturally occurring radioactive elements. A renewed interest in this field was generated after 1934 when it was discovered by Curie and Joliot that radioactive elements could be artificially …
A Study Of The Kinetics Of The Oxidation Of Uranium(Iv) By Cerium(Iv), Floyd Beatty Baker
A Study Of The Kinetics Of The Oxidation Of Uranium(Iv) By Cerium(Iv), Floyd Beatty Baker
Chemistry and Chemical Biology ETDs
The kinetics of a number of oxidation-reduction reactions and exchange reactions involving cations of the transition and inner transition elements have been extensively reviewed by T. W. Newton and S. W. Rabideau. These workers represent the formation of the activated complex by an equation which includes only the principal species in solution as reactants.
Spectroscopic Studies Of Metal-Cyanide Complexes: Part 1: Infrared And Visible Absorption Studies Of Cyanide Complexes Of Ni(Ii) In Aqueous Solution, Part 2: An Analysis Of The Infrared Vibrational Spectra Of The Tetracyanonickelate(Ii) Ion In The Solid State, Roy L. Mccullough
Chemistry and Chemical Biology ETDs
In this work, further evidence has been collected establishing the existence of a new ionic species in solutions of sodium tetracyanonickelate(II) and sodium cyanide. Contrary to the literature, however, this work shows that the species is [Ni(CN)5]-3 rather than [Ni(CN)6]-4.
Liquid Scintillators. Some Aryl Substituted Phenanthrenes And Dihydrophenanthrenes, And Related P-Terphenyls And P-Quaterphenyls, Stephen Paul Birkeland
Liquid Scintillators. Some Aryl Substituted Phenanthrenes And Dihydrophenanthrenes, And Related P-Terphenyls And P-Quaterphenyls, Stephen Paul Birkeland
Chemistry and Chemical Biology ETDs
With the advent of good commercially available photomultiplier tubes, scintillation counters have become increasingly popular for laboratory use. Although there are a number of materials such as ionic crystals, covalent crystals, plastics, and liquid organic solutions, which are used in scintillation counters, liquid organic solutions offer distinct advantages. Because the organic solutes used in liquid scintillation systems have decay times of the order of 10-8 second, systems with resolving times of the order of 5x10-10 second may be obtained. This represents an improvement by a factor of 104 over gas counters and 102 over scintillation systems …
A Spectrophotometric Study Of The Analytical Chemistry Of Vanadium, Kenton E. Bentley
A Spectrophotometric Study Of The Analytical Chemistry Of Vanadium, Kenton E. Bentley
Chemistry and Chemical Biology ETDs
Vanadium is most frequently encountered in analytical chemistry in the volumetric determination of vanadium by oxidation-reduction titration. Vanadium is rarely determined gravimetrically and finds little use as a reagent in gravimetric analysis. The simple ionic forms of the valence states of vanadium and the colors of acidic, aqueous solutions of these ions, as reported in the literature, are listed in Table 1. There is some confusion in the nomenclature of the ionic forms; that given in Table 1 is by analogy to chromium.
The Synthesis Of Some Triazole Derivatives, John M. Collier
The Synthesis Of Some Triazole Derivatives, John M. Collier
Chemistry and Chemical Biology ETDs
The triazoles have been known since the late 1800's when von Pechmann discovered the ring system during the course of his work with osazones. He first assigned the name "osotriazone" to the parent ring; this was later changed to "osotriazole", a name which is still retained for certain derivatives obtained from the sugar osazones.
The Synthesis Of Some Fluorine Derivatives As Potential Scintillation Solutes, Martin Dennis Barnett
The Synthesis Of Some Fluorine Derivatives As Potential Scintillation Solutes, Martin Dennis Barnett
Chemistry and Chemical Biology ETDs
In connection with work being carried out, in part, by the Biomedical Research Group, Los Alamos Scientific Laboratory, on the evaluation of organic compounds as solutes in liquid scintillation detector systems, it seemed of interest to investigate the liquid scintillation properties of fluorine analogues of p-terphenyl and p-quaterphenyl. These compounds have been shown to possess remarkable scintillation properties; however, the use of p-quaterphenyl has been severely curtailed by its low solubility in toluene. Accordingly, the synthesis of a number of 2- and 2,7-substituted fluorines was carried out in an effort to obtain a more soluble, completely conjugated aromatic system and …
Thermodynamic Properties Of The System Pucl3-Kcl, Robert Benz
Thermodynamic Properties Of The System Pucl3-Kcl, Robert Benz
Chemistry and Chemical Biology ETDs
It is a general experimental result that as the temperature of a chemical system is increased the thermodynamic parameters of state become more important while the diffusion controlled and other activation type parameters become less important in controlling the net chemical reaction. The growing intereats in chemical processing of plutonium materials at elevated temperatures has emphasied the importance of an accurate knowledge of the thermodynamic data tor plutonium compounds as an aid to the prediction and the study of possible economically feasible processes.
Synthesis Of 4, 7-Disubstituted Derivatives Of Imidazo-[4, 5-D]-Pyridazine And Related Compounds, William Seese
Synthesis Of 4, 7-Disubstituted Derivatives Of Imidazo-[4, 5-D]-Pyridazine And Related Compounds, William Seese
Chemistry and Chemical Biology ETDs
The antitumor activity of 8-azaguanine (5-amino-7-hydroxy-v-triasolo([d] pyrimidine) (A) prompted the preparation of the imidazo-[4, 5-d] pyridazine ring system (B). In this ring the two nitrogen atoms are adjacent in the six-membered ring with the five-membered imidazole ring remaining the same as in the parent purine ring (C).
Some Aspects Of The Non-Aqueous Chemistry Of The Uranium Chlorides, Richard E. Panzer
Some Aspects Of The Non-Aqueous Chemistry Of The Uranium Chlorides, Richard E. Panzer
Chemistry and Chemical Biology ETDs
Uranium, discovered by Klaproth in 1789, has been the object of greatly intensified chemical and physical studies since the establishment of the Manhattan Project. An event such as the discovery of the hexachloride of uranium in 1943 points up the relatively unknown status of the chemistry of this element at a fairly recent date. It is not, therefore, surprising that the chemistry of many compounds of greater complexity than the hexachloride had not been investigated. However, with the search intensified for methods of separation of the naturally occurring isotopes for subsequent use in nuclear weapons and reactors, the years since …
The Magnesium-Hydrogen System, J. Frederick Stampfer Jr.
The Magnesium-Hydrogen System, J. Frederick Stampfer Jr.
Chemistry and Chemical Biology ETDs
The motivating factor for this investigation of the magnesium-hydrogen system was the recent interest in the hydride of beryllium. Although beryllium hydride has been prepared by the pyrolysis of di-t-butylberyllium, no evidence for the direct union of beryllium and hydrogen has been reported. It was thought that an examination of the reaction between magnesium and hydrogen and determination of the thermodynamic relations involved might have a bearing on this phenomenon. Also, the properties of magnesium hydride are interesting from an over-all periodic table viewpoint. The hydrides of beryllium and magnesium are usually considered to be intermediary between the saline, or …
The Extraction Of Scandium, Yttrium, And Lanthanum Using Various Monoalkyl Orthophosphoric Acids, Clarence Gerald Warren
The Extraction Of Scandium, Yttrium, And Lanthanum Using Various Monoalkyl Orthophosphoric Acids, Clarence Gerald Warren
Chemistry and Chemical Biology ETDs
The separation of lanthanum, yttrium, and the rare earth elements from their ores has been a challenge to the chemist for many years. The similarity in chemical properties has made their separation a problem of extraordinary difficulty. Fractional crystallization has been the classical method utilized in the past, although individual elements have been isolated by oxidation or reduction to other than the tripositive oxidation state (1). Recently ion exchange and solvent extraction methods have become more important as a means of separation of these elements. Both of these techniques depend upon fractional differences in the distribution of compounds or ions …
Absorption Of Antimony(Iii) And Indium From Anhydrous Acetic Acid By Ion Exchange Resins, Robert Tor Lofberg
Absorption Of Antimony(Iii) And Indium From Anhydrous Acetic Acid By Ion Exchange Resins, Robert Tor Lofberg
Chemistry and Chemical Biology ETDs
Organic ion exchange resins are a comparatively recent development. In 1935 Adams and Holmes prepared the first ion exchange resin by polymerizing polyhydric phenols with formaldehyde. The condensation product exhibited definite reversible cation exchange properties. The success of this experiment led them to the development of the first anion exchange resin which was prepared by the polymerization of phenylenediamine with formaldehyde. The publication of these experiments inspired many similar investigations leading directly to the manufacture of the numerous ion exchange resins now commercially available.