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Synthesis, scale-up, and characterization of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105)

Description: We have synthesized 4OOg of the new, insensitive, energetic heterocycle, 2,6-diamino-3,5-dinitropyrazine-l-oxide (LLM-105) with 81% the energy of HMX and excellent thermal stability. The synthesis is a three step reaction sequence from the commercially available starting material, 2,6-dichloropyrazine, with an overall yield of 36%. In this paper we will describe the scale-up of the synthesis of LLM- 105 and report on performance and shock sensitivity experiments performed on this material.
Date: April 27, 1998
Creator: Pagoria, P. F.
Partner: UNT Libraries Government Documents Department

Quantum symmetry and photoreactivity of azabenzenes

Description: The fundamental processes associated with a photochemical reaction are described with reference to experimental properties of azabenzenes. Consideration of both excitation and relaxation processes led to presentation of the symmetry propagator, a unifying principle which maps system fluctuations (perturbations acting on an initial state) with dissipations (transitions to different states), thus directing the energy flow along competing reactive and nonreactive pathways. A coherent picture of relaxation processes including chemical reactions was constructed with the aid of spectroscopic data. Pyrazine (1,4 diazine) possesses vibronically active modes which provide an efficient mechanism for internal conversion to the first excited singlet state, where other promoting modes of the correct symmetry induce both intersystem crossing to the triplet manifold, isomerization through diaza-benzvalene, and chemical reactions through cycloreversion of dewar pyrazine to yield HCN plus an azete. At higher energies simple H atom loss and internal conversion become more predominant, leading to ring opening followed by elimination of methylene nitrile and ground state reaction products. Efficiency of chemical transformations as dissipation mechanisms versus competing fluorescence, phosphorescence and radiationless relaxation was mapped from near ultraviolet to far ultraviolet by photodissociation quantum yields into reaction channels characterized by molecular beam photofragment translational spectroscopy. A reaction path model for azabenzene photochemistry was presented and tested against experiment. Presence of undiscovered channels in other azabenzene systems was predicted and verified. The dominant process, HCN elimination, was resolved into three distinct channels. Both molecular and atomic hydrogen elimination was observed, the former with significant vibrational excitation. Small yields of isomerization products, acetylene and N2, were also observed.
Date: June 1995
Creator: Chesko, J. D. M.
Partner: UNT Libraries Government Documents Department

A diethyl phosphonate containing oxazoline: Synthesis and characterization of monomer and homopolymer

Description: A diethyl phosphonate oxazoline monomer and its polymer have been synthesized. The monomer appears to polymerize via a ring-opening mechanism giving the expected polyethyleneimine backbone with pendant carbonyl groups. Two distinct molecular weights were produced during polymerization suggesting two mechanisms of chain growth. Studies are underway to elucidate the reasons for this. This polymer has potential as a metal-chelating agent.
Date: May 1, 1995
Creator: Hermes, R.E.; Thompson, R.D. & Valdez, L.S.
Partner: UNT Libraries Government Documents Department

Electrochemically-modulated liquid chromatography (EMLC): Column design, retention processes, and applications

Description: This work describes the continued development of a new separation technique, electrochemically-modulated liquid chromatography (EMLC), from column design, retention mechanisms to pharmaceutical applications. The introduction section provides a literature review of the technique as well as a brief overview of the research in each of the chapters. This section is followed by four chapters which investigate the issues of EMLC column design, the retention mechanism of monosubstituted aromatic compounds, and the EMLC-based applications to two important classes of pharmaceutical compounds (i.e., corticosteroids and benzodiazepines). These four sections have been removed to process separately for inclusion on the database. The dissertation concludes with a general summary, a prospectus, and a list of references cited in the General Introduction. 32 refs.
Date: October 8, 1997
Creator: Ting, E. Y.
Partner: UNT Libraries Government Documents Department


Description: A review of research that has contributed to a better understanding of the solubility relations among vicdioximes is presented. Included are sections on synthesis, analysis, structure, and analytical uses of these complexes (J.R.D.)
Date: March 1, 1962
Creator: Banks, C.V.
Partner: UNT Libraries Government Documents Department

Chemical and biological studies on nucleic acids and derivatives. Progress report, May 1, 1975--July 31, 1976

Description: The photochemical products from N-oxidized purines in solution are strongly dependent on the tautomeric and ionic state of the compounds. Studies have been done on the effect of pH on the quantum efficiencies of photoreduction and photorearrangement of a 1-hydroxypurine, a purine 3-oxide and hypoxanthine 3-oxide, a compound that exists as a tautomeric N-oxide-N-hydroxyl equilibrium. The quantum yields for each photoreaction from each tautomer of the nonionized species and from the anions have been determined. In every case photoreduction is promoted in the presence of triplet sensitizers.
Date: October 1, 1976
Creator: Brown, G. B. & Parham, J. C.
Partner: UNT Libraries Government Documents Department

Environmental significance of biocatalytic conversion of low grade oils

Description: Studies dealing with the interactions between extremophilic microorganisms and crude oils have led to the identification of biocatalysts which through multiple biochemical reactions catalyze desulfurization, denitrogenation, and demetalation reactions in oils. Concurrently, the oils are also converted to lighter oils. These complex biochemical reactions have served as models in the development of the crude oil bioconversion technology to be applied prior to the treatment of oils by conventional chemical processes. In practical terms, this means that the efficiency of the existing technology is being enhanced. For example, the recently introduced additional regulation for the emission of nitrogen oxides in some states restricts further the kinds of oils that may be used in burners. The biocatalysts being developed in this laboratory selectively interact with nitrogen compounds, i.e. basic and neutral types present in the oil and, hence, affect the fuel NOx production. This, in turn, has a cost-efficient influence on the processed oils and their consumption. In this paper, these cost-efficient and beneficial effects will be discussed in terms of produced oils, the lowering of sulfur and nitrogen contents, and the effect on products, as well as the longevity of catalysts due to the removal of heteroatoms and metal containing compounds found in crudes.
Date: September 1, 1996
Creator: Lin, M.S.; Premuzic, E.T.; Lian, H.; Zhou, W.M. & Yablon, J.
Partner: UNT Libraries Government Documents Department

[Towards computer-aided catalyst design: Three effective core potential studies of C-H activation]. Final report

Description: Research in the initial grant period focused on computational studies relevant to the selective activation of methane, the prime component of natural gas. Reaction coordinates for methane activation by experimental models were delineated, as well as the bonding and structure of complexes that effect this important reaction. This research, highlighted in the following sections, also provided the impetus for further development, and application of methods for modeling metal-containing catalysts. Sections of the report describe the following: methane activation by multiple-bonded transition metal complexes; computational lanthanide chemistry; and methane activation by non-imido, multiple-bonded ligands.
Date: December 31, 1998
Partner: UNT Libraries Government Documents Department

[Photochemistry of intermolecular C-H bond activation reactions]. Progress report, [September 15, 1994--March 15, 1995]

Description: Since the last progress report (March 15, 1994), attention was paid to the solution photochemistry of (HBPz*{sub 3})Rh(CO){sub 2} (Pz* = 3,5-dimethylpyrazolyl) at different excitation wavelengths and in various hydrocarbon solvents (n-pentane). Absolute quantum efficiencies were obtained for the intermolecular C-H bond activation at different wavelengths and temperatures. Results indicate that there are two excited states with different reactivities and two reaction channels. The intermediate that is highly reactive toward hydrocarbon C-H bonds is probably the monocarbonyl (HBPz*{sub 3})Rh(CO) species. Related studies are being carried out on tungsten(IV) eight-coordinate-chelate complexes.
Date: December 15, 1994
Creator: Lees, A.J.
Partner: UNT Libraries Government Documents Department

Singlet oxygen and organic light-emitting diodes

Description: The preparation of light emitting diodes employing a new class of materials, 5,10-dihetera 5,10-dihydro-indeno[3,2b]indenes, as hole transport agents is described. These materials have been found to be more resistant to degradation by singlet oxygen than a poly(p-phenylene vinylene) (PPV) derivative.
Date: July 1, 1995
Creator: Jacobs, S.J.; Sinclair, M.B.; Valencia, V.S.; Kepler, R.G.; Clough, R.L.; Scurlock, R.D. et al.
Partner: UNT Libraries Government Documents Department


Description: Sequential autoradiographed sections through the shoot apical meristem of Arabidopsis thaliana treated for six hours with a solution of H/sup 3/- thymidine in combination with 0.1% Tween 20 and dilute mineral solution reveal a differential pattern of labeling, indicative of differential rates of DNA synthesis. This pattern corresponds to the histological zonation of the apex and reveals a sub-apical block of cells in which the amount of incorporation is significantly lower than in the adjacent flank cells. (auth)
Date: January 1, 1962
Creator: Brown, J.A.M.; Miksche, J.P. & Smith, H.H.
Partner: UNT Libraries Government Documents Department


Description: Recent the orbital symmetry rules have been shown to apply to hetero-atom systems such as nitrone thermal cycloaddition reactions and the thermal and photochemical aziridine ring cleavage at the C-C bond. The concerted photocyclization is disrotatory and the reverse thermal cleavage is conrotatory in these molecules with four {pi} electrons. In contrast to the azomethine ylide-aziridine system, the stereochemistry of the nitrone photocyclization to oxaziridine can only be observed on carbon and nitrogen atoms because the oxygen atom has lone pair electrons instead of substituents. For the reverse thermal ring opening of oxaziridine to the nitrone, the two possible conrotatory motions of C-O bond cleavage should result in a mixture of the cis and trans-isomers of the nitrone, in contrast to the photoclosure which should be stereospecific.
Date: June 1, 1971
Creator: Splitter, Janet S.; Su, Tah-mun; Ono, Howard & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department


Description: Reversible photoinduced electron paramagnetic resonance (EPR) signals and photoconductivity were observed when a solution of tetracyancethylene (TCNE) in tetrahydrofuran (THF) was irradiated in the charge-transfer band of the complex formed between these two compounds. The eleven-line hyperfine structure of the EPR spectrum which was obtained demonstrated the presence of TCNE negative ion radical. The concentration of this radical was found to be directly proportional to the square root of the light intensity. Second order decay kinetics were followed when the light was shut off. Both the EPR signal and the photoconductivity rose initially as the square of the time. The latter portions of the growth curves could be fit to the latter portions of a hyperbolic tangential growth curve. From these data a reaction mechanism was proposed. The rate law dn/dt + kn{sup 2} = {alpha}L(1-e{sup -{beta}t}) = 0, where n = the concentration of radicals, t = the time, k, {alpha}, and {beta} are rate constants, and L = the light intensity, described both the photo-induced EPR and the photoconductivity within the limits of experimental accuracy.
Date: December 8, 1964
Creator: Ilten, David F. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department


Description: It was noted previously that 3-(p-dimethylamino)-2-phenyloxaziridine (I) and 3-(p-dimethylamino)-2-(m-nitrophenyl)oxaziridine were photosensitive. Further study on the irradiation (in a variety of solvents under nitrogen) of (I), 2,3-diphenyloxaziridine (II), and 3-(p-nitrophenyl)-2-phenyloxaziridine (III) indicates the major photoreaction to be cleavage to the aldehyde and an intermediate which forms aniline and azobenzene. There is also formed in the photolysis varying amounts of the corresponding anilide. A table provided gives the yields in three different solvents.
Date: August 30, 1967
Creator: Splitter, Janet S. & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

Insensitive explosive

Description: This invention relates to the field of chemistry and, more particularly, to explosives. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36). It is desirable to use explosives in weapons and other applications which are less sensitive than the common explosives RDX, TNT, and HMX, since there have been catastrophic explosions of munitions which use these compounds. In preliminary characterization and sensitivity testing, it has been found that 3-amino-5-nitro-1,2,4-triazole (ANTA) is a promising insensitive high explosive. This report details the safety, production, and physical properties of ANTA.
Date: December 31, 1991
Creator: Lee, Kien-yin & Storm, C.B.
Partner: UNT Libraries Government Documents Department

Biochemical processing of heavy oils and residuum

Description: During the past several decades, the petroleum industry has adjusted gradually to accommodate the changes in market product demands, government regulations, and the quality and cost of feedstock crude oils. For example, the trends show that the demand for distillate fuels, such as diesel, as compared to gasoline are increasing. Air-quality standards have put additional demand on the processing of heavier and higher sulfur feed stocks. Thus, the 1990 Clean Air Act amendments require the industry to produce greater quantities of oxygenated gasoline, and lower sulfur diesel and reformulated gasoline. Biochemical technology may play an important role in responding to these demands on the petroleum industry.
Date: May 1, 1995
Creator: Lin, M.S.; Premuzic, T.; Yablon, J.H. & Zhou, Wei-Min
Partner: UNT Libraries Government Documents Department

Intramolecular energy- and electron-transfer reactions in polymetallic complexes. Annual report

Description: The complexes (tpy)Ru(II)(tpp)Co(III)(PPhEt{sub 2})H{sub 2}{sup 3+}, (NC){sub 3}Fe(II)(tpp)Co(III)(PPhEt{sub 2})H{sub 2} and (NC){sub 3}Fe(II)(tpp)Co(III)(PPh{sub 3})H{sub 2} (where tpp = 2,3,5,6-tetrakis(2{prime}-pyridyl)pyrazine), were prepared and their photochemistry studied. Reasons for the low quantum yields for H{sub 2} production are discussed briefly. A series of FeRuRh complexes is being prepared. Plans for the coming year on intramolecular energy transfer and charge separation are discussed.
Date: December 1, 1991
Creator: Peterson, J.D.
Partner: UNT Libraries Government Documents Department

Factoring the contribution of through-space and through-bond interactions to rates of photoinduced electron transfer in donor- spacer-acceptor molecules using ultrafast transient absorption spectroscopy

Description: Contributions from through-space and through-bond interactions to the electronic coupling matrix elements for photoinduced charge separation and recombination in linked donor-spacer-acceptor molecules were studied. The molecules consisted of a 4-piperidinyl-naphthalene-1,8-dicarboximide electron donor and a N-(n-octyl)pyromellitimide electron acceptor attached to the 1,5- and 1,8-positions of either anthracene or dibenzobicyclo(2.2.2)octatriene spacers.
Date: June 1996
Creator: Gosztola, D.; Wang, Bing & Wasielewski, M. R.
Partner: UNT Libraries Government Documents Department