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Results for “HETEROCYCLIC COMPOUNDS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Abiotic synthesis of purines and other heterocyclic compounds by the action of electrical discharges

The synthesis of purines and pyrimidines using Oparin-Urey-type primitive earth atmospheres has been demonstrated by reacting methane, ethane, and ammonia in electrical discharges. Adenine, guaine, 4-aminoimidazole-5-carboxamide (AICA), and isocytosine have been identified by UV spectrometry and paper chromatography as the products of the reaction. The total yields of the identified heterocyclic compounds are 0.0023 percent. It is concluded that adenine synthesis occurs at a much lower concentration of hydrogen cyanide than has been shown by earlier studies. Pathways for the synthesis of purines from hydrogen cyanide are discussed, and a comparison of the heterocyclic compounds that have been identified in meteorites and in prebiotic reactions is presented.

Yuasa, S.↗
DOE OSTI2017

Structure-forming role of heterocyclic compounds in the synthesis of metal-organic frameworks based on cadmium(II)

The influence of heterocyclic compounds on the formation of coordination polymers in the system of cadmium(II) nitrate tetrahydrate and biphenyl-4,4′-dicarboxylic acid is demonstrated. Two new coordination polymers [Cd(H{sub 2}O)(bpdc)(im){sub 2}] (1, bpdc{sup 2–} is biphenyl-4,4′-dicarboxylate, im is imidazole) and [(CH{sub 3}){sub 2}NH{sub 2}]{sub 4}[Cd{sub 6}(dmf)(bpdc){sub 8}]·10DMF (2) were obtained under solvothermal conditions in the presence of imidazole or benzimidazole, respectively. Product 1 has a chain structure, while compound 2 possesses a three-dimensional structure with the hex topology. The obtained compounds were characterized by IR spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Effect of pressure on heterocyclic compounds: Pyrimidine and s-triazine

We have examined the high-pressure behaviors of six-membered heterocyclic compounds of pyrimidine and s-triazine up to 26 and 26.5 GPa, respectively. Pyrimidine crystallizes in Pna2{sub 1} symmetry (phase I) with the freezing pressure of 0.3 GPa, and transforms to another phase (phase II) at 1.1 GPa. Raman spectra of several compression-decompression cycles demonstrate there is a critical pressure of 15.5 GPa for pyrimidine. Pyrimidine returns back to its original liquid state as long as the highest pressure is below 15.1 GPa. Rupture of the aromatic ring is observed once pressure exceeds 15.5 GPa during a compression-decompression cycle, evidenced by the amorphous characteristics of the recovered sample. As for s-triazine, the phase transition from R-3c to C2/c is well reproduced at 0.6 GPa, in comparison with previous Raman data. Detailed Raman scattering experiments corroborate the critical pressure for s-triazine may locate at 14.5 GPa. That is, the compression is reversible below 14.3 GPa, whereas chemical reaction with ring opening is detected when the final pressure is above 14.5 GPa. During compression, the complete amorphization pressure for pyrimidine and s-triazine is identified as 22.4 and 15.2 GPa, respectively, based on disappearance of Raman lattice modes. Synchrotron X-ray diffraction patterns and Fourier transform infrared spectra of recovered samples indicate the products in two cases comprise of extended nitrogen-rich amorphous hydrogenated carbon (a-C:H:N)

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1947

Knock-Limited Power Outputs from a CFR Engine Using Internal Coolants: Four Alkyl Amines, Three Alkanolamines, Six Amides, and Eight Heterocyclic Compounds - 3

An investigation of the antiknock effectiveness of various additive-water solutions when used as internal coolants has been conducted at the NACA Cleveland laboratory. Nine compounds have been previously run in a CFR engine and the results are presented. In an effort to find a good anti-knock-coolant additive with more desirable physical properties than those of the nine compounds previously investigated, water solutions of four alkyl amines, three alkanolamines, six amides, and eight heterocyclic compounds were investigated and the results are presented.

Imming, Harry S.↗
DOE OSTI2016

Reaction Pathways and Intermediates in Selective Ring Opening of Biomass-Derived Heterocyclic Compounds by Iridium

While the catalytic hydrogenolysis of biomass-derived aromatic cyclic compounds to functionalized long chain alcohols and polyols has been known for decades, the factors that control the selectivity remain either unknown or controversial. Previous reports have hypothesized full ring saturation of the aromatic ring is necessary prior to hydrogenolysis. Contradictorily, recent studies have shown hydrogenolysis occurs prior to the saturation of the conjugated bonds. Furthermore, it has been assumed the functional groups present are fully reduced prior to hydrogenolysis; however, this has not been shown a priori. In order to resolve these controversies, we combine density functional theory and high-resolution electron energy loss spectroscopy (HREELS) to probe the catalytic hydrogenolysis of saturated and unsaturated heterocyclic molecules (furan, furfural, furfuryl alcohol, and tetrahydrofurfuryl alcohol) on iridium. Our results reveal that full saturation of the aromatic ring is not only unnecessary but leads to slower kinetics and differing selectivities. In contrast to previous studies, we show selective partial ring saturation can enhance the kinetics of the hydrogenolysis process. We report reduction/oxidation of the functional group leads to a change in the electronegativity, resulting in a change in selectivity. These results provide important mechanistic insights allowing for further improvement of catalysts for the effective transformations of biomass-derived oxygenates to value-added products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Prebiotic hydrocarbon synthesis in impacting reduced astrophysical icy mixtures

We present results of prebiotic organic synthesis in shock-compressed reducing mixtures of simple ices from quantum molecular dynamics simulations extended to close to chemical equilibrium timescales. Given the relative abundance of carbon in reduced forms in astrophysical ices as well as the tendency of these mixtures to form complex hydrocarbons under the presence of external stimuli, it is possible that cometary impacts on a planetary surface could have yielded a larger array of prebiotic organic compounds than previously investigated. We find that the high pressures and temperatures due to shock compression yield a large assortment of carbon- and nitrogen-bonded extended structures that are highly reactive with short molecular lifetimes. Expansion and cooling causes these materials to break apart and form a wide variety of stable, potentially life-building compounds, including long-chain linear and branched hydrocarbons, large heterocyclic compounds, and a variety of different amines and exotic amino acids. Lastly, our results help provide a bottom-up understanding of hydrocarbon impact synthesis on the early Earth and its role in producing life-building molecules from simple starting materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Comprehensive End-To-End Design of Novel High Energy Density Materials: III. Fused Heterocyclic Energetic Compounds

In contrast to synthesis and experimental characterization that are usually expensive and time-consuming, a coupled combination of ab initio and group additive theoretical methods represents a powerful alternative to computationally design and characterize new materials with targeted properties. Heterocyclic energetic materials are considered attractive candidates to replace conventional high explosives, such as PETN, RDX, HMX, and TNT. Heterocycles enable an intriguing opportunity for combinatorial design of new classes of energetic materials with targeted performance and sensitivity properties and offer ways for an accurate analysis of structure–property correlations of the materials. By using a computational strategy that links methods of quantum chemistry and semiempirical statistical analysis, we designed, modeled, and characterized a series of novel linear and fused explosive compounds. Proposed materials with best combinations of performance and sensitivity parameters can be now considered as potential candidates for synthesis and experimental characterization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Vibronic states in organic semiconductors based on non-metal naphthalocyanine. Detection of heterocyclic phthalocyanine compounds in a flexible dielectric matrix

The vibronic properties of semiconductor structures based on non-metal naphthalocyanine molecules are studied using IR and Raman spectroscopy methods. New absorption lines in the transmission spectra of such materials are detected and identified. Three transmission lines are observed in the range 2830-3028 cm{sup -1}, which characterize carbon-hydrogen bonds of peripheral molecular groups. Their spectral positions are 2959, 2906, and 2866 cm{sup -1}. It is detected that the phthalocyanine ring can also exhibit its specific vibronic properties in the Raman spectra at 767, 717, and 679 cm{sup -1}. The naphthalocyanine molecule in the organic dielectric matrix of microfibers is described using IR spectroscopy. It is shown that the set of vibrations characterizing the isoindol group, pyrrole ring, naphtha group, and C-H bonds, allows an accurate enough description of the vibronic states of the naphthalocyanine complex in complex heterostructures to be made. The spectral range with fundamental modes, characterizing a naphthalocyanine semiconductor in a heterostructure, is 600-1600 cm{sup -1}. A comparison of the compositions of complex systems with a similar heterostructure containing lutetium diphthalocyanine demonstrated few errors.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Direct Aqueous Photochemistry of Isoprene High-NOx Secondary Organic Aerosol

Secondary organic aerosol (SOA) generated from the high-NOx photooxidation of isoprene was dissolved in water and irradiated with {lambda} > 290 nm light to simulate direct photolytic processing of organics in atmospheric water droplets. High-resolution mass spectrometry was used to characterize the composition at four time intervals (0, 1, 2, and 4 h). Photolysis resulted in the decomposition of high molecular weight (MW) oligomers, reducing the average length of organics by 2 carbon units. Approximately 65% by count of SOA molecules decomposed during photolysis, accompanied by the formation of new products. An average of 30 % of the organic mass was modified after 4 h of direct photolysis. In contrast, only a small fraction of the mass (<2 %), belonging primarily to organic nitrates, decomposed in the absence of irradiation by hydrolysis. We observed a statistically-significant increase in average O/C, decrease in H/C, and increase in N/C ratios resulting from photolysis. Furthermore, the concentration of aromatic compounds increased significantly during photolysis. Approximately 10 % of photodegraded compounds and 50 % of the photoproducts contain nitrogen. Organic nitrates and multifunctional oligomers were identified as compounds degraded by photolysis. Low-MW 0N (compounds with 0 nitrogen atoms in their structure) and 2N compounds were the dominant photoproducts. Fragmentation experiments using tandem mass spectrometry (MSn, n = 2-3) indicate that the 2N products are likely heterocyclic/aromatic and are tentatively identified as furoxans. Although the exact mechanism is unclear, these 2N heterocyclic compounds are produced by reactions between photochemically-formed aqueous NOx species and SOA organics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Reaction of phenyl-containing N-substituted 1,3-oxazolidines and 1,3-oxazinanes with triammine(tricarbonyl)chromium

New heterocyclic compounds with phenyl chromium tricarbonyl substituents were synthesized by the reaction of triammine(tricarbonyl)chromium with phenyl-substituted 1,3-oxazacy-cloalkanes bearing acetyl, tert-butyloxycarbonyl, or phenyl group at the nitrogen atom. The resulting compounds were isolated in the individual state and characterized by physicochemical methods of analysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Synthesis and study of new phenolic antioxidants with nitroaromatic and heterocyclic substituents

New polyfunctional aromatic, nitroaromatic, and heterocyclic compounds linked to the 2,6-di-tert-butylphenol moiety via –NH–, –C(O)NH–, –S–, or–C=N– spacers were synthesized. These structures provide intramolecular charge transfer (ICT) and exhibit antioxidant activity. The structures of the new compounds were established by X-ray diffraction. The novel compounds were evaluated for antioxidant activity using the DPPH assay. The presence of the 2,4,6-trinitrophenyl moiety in combination with the –NH– spacer leads to a considerable increase in the antioxidant activity of 2,6-di-tert-butylphenols. These compounds are also weak lipoxygenase inhibitors. The results of this study provide an opportunity to search for new types of antioxidants with ICT.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗