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Wyszukujesz frazę "Friedl, Z." wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
The Relationship Between the Heats of Formation and the Molecular Electrostatic Potentials of Polyazaarenes
Autorzy:
Bartošková, M.
Friedl, Z.
Powiązania:
https://bibliotekanauki.pl/articles/358483.pdf
Data publikacji:
2013
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
high-nitrogen compounds
azines
azoles
heat of formation
molecular surface electrostatic potential
Opis:
In order to characterize the explosive properties of high-nitrogen, energetic compounds, the heats of formation, either in the gas or the solid state, are often used as preliminary data. Their relationship to the number of nitrogen atoms involved is usually known, so exploring it cannot furnish any new information. However, the very promising, quantitative structure property relationship (QSPR) approach utilizes the molecular surface electrostatic potential V(r). We have therefore performed calculations for 12 azines and 10 azoles by the DFT B3PW91/cc-pVTZ method, and constructed their gas phase heats of formation Δf H°(298,g) by means of the isodesmic reaction approach. The acquired gas phase heats of formation Δf H°(298,g) were correlated with the molecular surface electrostatic potentials VS,max, VS,min, and VS(ring), which were calculated by the B3LYP/6-31G(d,p)//B3PW91/cc-pVTZ method. It is shown that the VS(ring) electrostatic potential describes very precisely the structures of high-nitrogen N-heteroaromatics, with both consecutive and isolated nitrogen atoms, and their thermodynamic properties.
Źródło:
Central European Journal of Energetic Materials; 2013, 10, 1; 103-112
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of C-NO2 Bonds in Nitroaromatic Compounds: A Bond Disproportionation Approach
Autorzy:
Pexa, M.
Friedl, Z.
Powiązania:
https://bibliotekanauki.pl/articles/358691.pdf
Data publikacji:
2010
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
bond dissociation energy
bond disproportionation energy
nitro benzenes
nitro toluenes
detonation velocity
Opis:
Homolytic dissociation of C-NO2 bond represents the primary fssion process of nitroaromatic compounds under thermal, impact, shock and electric spark initiation stimuli. Homolytic bond dissociation energies BDE(C-NO2) describe the C-NO2 bond fssion. Theoretical calculations of BDEs are substantially infuenced by inadequate treatment of electron correlation. Recently the alternative method was suggested to overcome this substantial drawback – an isodesmic reaction RC-NO2 + SC-H → RC-H + SC-NO2 where SC-NO2 is standard nitroaromatic compound. This reaction is characterized by bond disproportionation energy DISP(C-NO2), which inherently cancels the electron correlation effect accompanying homolytic bond dissociation energies. The bond disproportionation energies DISP(C-NO2) and bond dissociation energies BDE(C-NO2) were evaluated for 11 nitro benzenes and 19 nitro toluenes at DFT B3LYP/6-311+G(d,p) level and correlated with their detonation velocities, D, and with charge of the most reactive nitro group, Q(NO2).
Źródło:
Central European Journal of Energetic Materials; 2010, 7, 2; 131-144
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Accounts of the new aspects of nitromethane initiation reactivity
Autorzy:
Zeman, S.
Atalar, T.
Friedl, Z.
Ju, X-H.
Powiązania:
https://bibliotekanauki.pl/articles/358898.pdf
Data publikacji:
2009
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
DFT B3LYP methods
detonation
initiation
nitromethane
Opis:
A well-known effect of amines, and also of water, on detonation characteristics of nitromethane (NM) is discussed from the point of view of the published knowledge about the study of initiation reactivity of this nitro paraffin. It is documented that bimolecular and higher interactions during the initiation of NM are impossible. The most widespread concepts of the primary steps of this initiation, i.e. formation of aci-NM anion [CH2=NO2]— by intermolecular hydrogen transfer in the neat NM submitted to shock and formation of this anion by action of an amine, have been scrutinized by the DFT B3LYP/cc-pVTZ+ method and evaluated as thermodynamically disadvantageous. Also the 1,3-intramolecular hydrogen shift in the NM molecule was characterized as a higher-barrier process. Two favorable primary mechanisms of fission in the NM initiation and development of its detonation were investigated by DFT B3LYP/cc-pVTZ+ calculations: homolysis of C–NO2 bond in the neat NM and homolysis of N–OH bond in its aci-form. The second mentioned pathway was found to be thermodynamically the most preferable mechanism of fission. Consequently, a detonation wave of NM with admixture of amine or water has a considerably reduced reaction zone length in comparison with the detonation of neat NM. The B3LYP/6-311++G(d,p) calculations of transition states revealed that an admixture of methylamine and/or water influences the conversion of nitromethane to its aci-form, and this effect is more feasible in the case of methylamine rather than water.
Źródło:
Central European Journal of Energetic Materials; 2009, 6, 1; 119-133
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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