Structural and functional diagnostics of ultrafine components in condensed high-energy systems

The study deals with octogen (HMX) and aluminum, which are among the most widely used components of condensed high-energy systems. The structure, thermal behavior and combustion parameters were determined for the octogen-based monofuels and octogen-aluminum binary systems at different dispersity of components. Irrespective of differences in thermal behavior, monofuels obtained with standard and ultrafine octogen powders were shown to have virtually identical combustion parameters. In the binary systems, replacement of standard microsized aluminum by ultrafine one increases the combustion rate by a factor of 2.5, and completeness of the metal reaction (oxidation) by a factor of 4.     

Tris-phosphorylated esters of symmetrical and unsymmetrical triols

By reaction of a series of triols and monosaccharides with 5,5-dimethyl-2-chloro-1,3,2-dioxaphosphorinane their tris-phosphorylated derivatives were synthesized, and the simplest chemical transformations of the latter were studied. Structures of the obtained P(V) derivatives were confirmed by ¹H, ¹³C and ³¹P NMR spectroscopy and by the MALDI TOF mass spectrometry and X-ray structural analysis.     

Stereoelectronic effects in N-C-S and N-N-C systems: experimental and ab initio AIM study

The energy of stereoelectronic interactions in N-C-S and N-N-C systems in tetrahydro[1,3,4]thiadiazolo[3,4- c][1,3,4]thiadiazole was estimated by means of R. W. Bader's quantum theory of "atoms in molecules" (AIM) and natural bond orbital analysis (NBO). The results were compared with those obtained by analysis of rho( r) derived from high-resolution X-ray diffraction data. The analysis of the data obtained allowed one to find a correlation between geometric characteristics of the stereoelectronic interactions, NBO mixing energies and the AIM properties of atoms. Significant variations of nitrogen atom atomic basin populations in different conformers were explained by sterical interactions between their electron lone pairs.     

3-aryl(alkyl)quinazoline-2,4(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>)-diones and their alkyl derivatives

Two-stage reaction of methyl anthranilate with aryl(alkyl) isocyanates in keeping with the quantumchemical calculations and XRD analysis resulted in 3-aryl(alkyl)quinazoline-2,4(1H,3H)-diones that by treatment with alkyl halides, phenacyl bromides, esters and amides of chloroacetic acid were converted into the corresponding 1-alkyl derivatives.     

A new methodology for producing pyrocarbon composites containing zerovalent iron nanoparticles

A magnetic pyrocarbon composite containing nanoparticles with an overwhelming predominance of zerovalent iron has been synthesized. The nanocomposite has a core–shell–matrix structure in which Fe⁰ nanoparticles with an average size of 50 nm are located in the pyrocarbon matrix and coated with a ferrite shell preventing their aggregation and oxidation. The composite is distinguished for its high thermal stability, magnetic properties 59 G cm³/g, and electrical conductivity as high as that of graphite.     

Dinitrogen Trioxide–Mediated Domino Process for the Regioselective Construction of 4‐Nitrofuroxans from Acrylic Acids

4‐Nitrofuroxans (4‐nitro‐1,2,5‐oxadiazole 2‐oxides) were prepared by a dinitrogen trioxide–mediated domino reaction of acrylic acids under the action of NaNO₂ excess in AcOH at room temperature. The reaction proceeds completely regioselectively and presents a new, simple, general, and safe method for the preparation of both 3‐aryl‐ and 3‐alkyl‐4‐nitrofuroxans available with difficulty before. A mechanism for the furoxan ring construction through a four‐step one‐pot protocol is proposed. The synthesized nitrofuroxans have been characterized by multinuclear NMR spectroscopy and X‐ray powder diffraction.     

Synthesis and separation of stereoisomeric 2,4,6,8-tetrasubstituted 3,7-dithia-1,5-diazabicyclo[3.3.0]octanes

Heterocyclization of hydrazine with aldehydes R-CHO (R = Me, Et, Prⁿ, Buⁿ, n-C₅H₁₁, Ph, 4-MeOC₆H₄, 3-Py) and H₂S leads to stereoisomeric 2,4,6,8-tetrasubstituted 3,7-dithia-1,5-diazabicyclo[3.3.0]octanes, which were separated by column chromatography. The trans-transoid-trans-configuration of tetramethyl(-ethyl,-propyl)-3,7-dithia-1,5-diazabicyclo-[3.3.0]octanes was inferred from the X-ray diffraction and ¹H and ¹³C NMR spectroscopic data.     

Synthesis and selected properties of N-substituted pyrrolo[2,1-c]-1,3-diazacycloalkano[1,2-a]pyrazinones

The reactions of methyl α-(2-formyl-1H-pyrrol-1-yl)carboxylates with N-substituted aliphatic 1,2-, 1,3-, and 1,4-diamines afford new pyrrole-containing heterocyclic systems: 1,2,3,10b-tetrahydroimidazo[1,2-a]pyrrolo[2,1-c]pyrazin-5(6H)-ones, 1,3,4,11b-tetrahydro-2H-pyrrolo[2′,1′:3,4]pyrazino[1,2-a]pyrimidin-6(7H)-ones, and 1,2,3,4,5,12b-hexahydro-pyrrolo[2′,1′:3,4]pyrazino[1,2-a][1,3]diazepin-7(8H)-ones. The reduction of these compounds with different reagents was studied.