Theoretical study of the unimolecular decomposition mechanisms of energetic TNAD and TNAZ explosives

Calculation methods based on hybrid Density Functional Theory (DFT) with the basis sets of the B3LYP/6‐31+G(d)//B3LYP/4‐31G(d) method and the differential overlap (INDO) program were used to derive reasonable decomposition mechanisms of 1,4,5,8‐tetranitro‐1,4,5,8‐tetraazadecalin (TNAD) and 1,3,3‐trinitroazetidine (TNAZ) explosives. All possible decomposition species and transition states, including intermediates and products, were identified and their corresponding enthalpy of formation and Gibbs free energy of formation were obtained using polyparametric modification equations. INDO bond energy calculation results reveal the weakest bonding site for reference and determine where cleavage can occur easily. This work is concerned mainly with eliminating HONO (cis or trans form). The activation energy for trans‐form HONO elimination is lower than that of cis‐form HONO elimination in the initial steps of both TNAD and TNAZ decomposition, being 18.5 kJ/mol and 33.3 kJ/mol, respectively. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Features of complexing of molecular NMR relaxation probes with cellulose acetates in solutions

The method of active and inert NMR relaxation probes can be used for determining the degree of substitution of cellulose acetates. The formation of hydrogen bonds between the hydroxyl and acetate groups of cellulose acetate is more probable than between the hydroxyl groups, which results in relative large shielding of the free OH groups in the polymer in samples with high degrees of substitution.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1761–1765, August, 1989.We would like to thank N. I. Naimark for providing the samples of the cellulose acetates.     

Mechanism and products of electrochemical reduction of 4-nitrophenyl-2,6-dimethyl-3,5-dicyano-1,4-dihydropyridines in dimethylformamide

Free anion radicals of the nitrobenzene and nitrosobenzene type, which were identified by EPR spectroscopy, are formed in the electrochemical reduction of isomeric 4-(nitrophenyl)-2,6-dimethyl-3,5-dicyano-1,4-dihydropyridines on mercury and solid electrodes. Reduction of the dihydropyridine ring is observed only for N-substituted p- and m-nitrophenyl derivatives of 1,4-dihydropyridine. An intermediate with a 2-pyridonemethide structure was identified; a set of primary and secondary chemical reactions that are associated with the electrolytic reduction of the investigated compounds is presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1494–1505, November, 1988.     

Mass spectra of alliosterol and its dehydration product and of allosides A and B

The EI and LSIMS mass spectra of alliosterol and its dehydration product and of allosides A and B have been studied. The spectra of alliosterol show features characteristic for sterols of the cholestane series. A comparison of the B/E spectra of some fragments of the ions from alliosterol and its dehydro product has shown the unimportance of the conversion of the former into the latter under mass-spectrometric conditions.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 344–349, May–August, 1992.     

Heterocyclic nitro compounds

The IR and Raman spectra of a number of anions of the nitro derivatives of 1,2,4-triazole were investigated. On the basis of the position of the absorption maxima of the asymmetric and symmetric t vibrations of the nitro group, it is assumed that the nitro groups in the 3 and 5 positions of the triazole ring are coplanar, which should lead to an increase in the participation of the nitro group in the de localization of the negative charge of the anion. Shifts of the frequencies as a function of the nature of the cation (NH₄, Na, K, Cs) were not detected in the IR spectra of the crystalline salts. In addition, the IR spectra of the crystalline salts are similar (with respect to the frequencies) to the spectra of aqueous solutions of the salts, which may serve as proof of the identical structure of the anions in crystals and aqueous solutions.See [1] for communication XII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 120–123, January, 1972.     

Synthesis,Characterization and Catalysis of Ce‐MCM‐41

The cerium‐containing MCM‐41 (Ce‐MCM‐41) has been synthesized by direct hydrothermal method. The low‐angle XRD patterns revealed the typical five major peaks of MCM‐41 type hexagonal structures. The interplanar spacing d₁₀₀ = 38.4 Å was obtained that can be indexed on a hexagonal unit cell parameter with a_o = 44.3 Å which was larger than that of pure siliceous MCM‐41 (Si‐MCM‐41). Transmission electron micrograph shows the regular hexagonal array of uniform channel characteristics of MCM‐41. The BET surface area of Ce‐MCM‐41 was 840 m²/g, which is much reduced as compared to that of Si‐MCM‐41, with the pore size of 26.9 Å and mesopore volume of 0.78 cm³/g were measured by nitrogen adsorption‐desorption isotherm at 77 K. Along with the results, the synthesized Ce‐MCM‐41 exhibited a well‐ordered MCM‐41‐type mesoporous structure with the incorporation of cerium. Using Ce‐MCM‐41 as a support, the Rh (0.5 wt%) catalyst exhibited very high activity for the NO/CO reactions.     

Phenyl and Phenylethyl Glycosides from Picrorhiza scrophulariiflora

Three new phenyl glycosides, scrophenoside A ( 1 ), B ( 2 ), and C ( 3 ), and two new phenylethyl glycosides, scroside D ( 4 ) and scroside E ( 5 ), were isolated from the stem of Picrorhiza scrophulariiflora Pennell (Scrophularlaceae), besides five known compounds. On the basis of spectroscopic evidence, the structures of the new compounds were elucidated as 4‐acetyl‐2‐methoxyphenyl 6‐O‐[4‐(β‐D ‐glucopyranosyloxy)vanilloyl]‐β‐D ‐glucopyranoside ( 1 ), 4‐acetylphenyl 6‐O‐[(E)‐p‐coumaroyl]‐β‐D ‐glucopyranoside ( 2 ), 4‐[(1R)‐ and (1S)‐1‐hydroxyethyl]‐2‐methoxyphenyl β‐D ‐glucopyranoside ( 3a and 3b , resp.), 2‐(3,4‐dihydroxyphenyl)ethyl O‐β‐D ‐glucopyranosyl‐(1→3)‐4‐O‐[(E)‐feruloyl]‐β‐D ‐glucopyranoside ( 4 ), and 2‐(3,4‐dihydroxyphenyl)ethyl O‐β‐D ‐glucopyranosyl‐(1→3)‐6‐O‐[(E)‐feruloyl]‐β‐D ‐glucopyranoside ( 5 ).     

Further Daphniphyllum Alkaloids from the Leaves of Daphniphyllum macropodum Miq.

Five new polycyclic Daphniphyllum alkaloids, macropodumines F ( 1 ) and G ( 2 ), 17‐oxoyuzurimine ( 3 ), and macropodumines H ( 4 ) and I ( 5 ), were isolated from the leaves of D. macropodum Miq ., collected in Sichuan Province, China. The structures and relative configurations of the new compounds – as well as of four known, related alkaloids – were elucidated on the basis of in‐depth spectroscopic and mass‐spectrometric analyses, by chemical derivatization, and by comparison of spectroscopic data with those of known compounds.