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The effect of nitrogen (III) oxide on the process of dinitrogen tetroxide separation in a dephlegmator during preparation of a «crude mixture» (HNO3-N2O4-N2O3-NO2- NO-H2O) in the production of concentrated nitric acid by direct synthesis was studied in this work. The dependence of crystallization onset on the composition of the N2O4-N2O3 mixture and temperature was determined. The refrigerant capable of maintaining the optimal temperature of the N2O4 extraction was suggested. The absence of nitrogen (III) oxide and nitrogen (I) oxide in the autoclave acid was confirmed. [ABSTRACT FROM AUTHOR]

A new solvate of a powerful explosive 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20) and liquid oxidizer N2O4 has been synthesized. When stored at room temperature, the white crystals turn yellowish brown, which indicates partial dissociation of N2O4 with the formation of a stable NO2 free radical, which is confirmed by ESR spectroscopy. The resulting solvate was analyzed by powder X‐ray diffraction, IR‐spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The vapor pressure of NO2 above the solvate crystals is similar to the pressure above common hydrates. The presence of the NO2 radical does not affect the thermal stability of CL‐20. However, under closed conditions, NO2 increases the rate of the autocatalytic decomposition reaction. The kinetics of this reaction at the surface temperature determine the burning rate of the solvate. The novel solvate has a high density (1.98 g cm−3), a high predicted detonation velocity and pressure, and sensitivity to impact slightly higher to that of ϵ‐CL‐20. [ABSTRACT FROM AUTHOR]

The oxidation of hexane-2,3,4,5-tetraone tetraoxime with dinitrogen tetroxide was studied in different solvents. The primary furoxan ring closure was found to occur involving either two central or two terminal oxime groups to form 4,7-dimethyl[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide and the previously unknown 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide. The structure of the latter compound was established by X-ray diffraction. [ABSTRACT FROM AUTHOR]

An efficient method for nitration of aliphatic and heterocyclic nitromethyl- ONN-azoxy derivatives with a mixture of concentrated nitric acid and dinitrogen tetroxide to give the corresponding dinitromethyl- ONN-azoxy compounds was developed. [ABSTRACT FROM AUTHOR]

The adsorption of dinitrogen tetroxide (N2O4) on multi-walled carbon nanotubes (MWCNTs) has been studied by FT-IR, Raman and X-ray photoelectron spectroscopy (XPS). The N2O4 adsorption is fully reversible, and after the desorption there is no evidences of MWCNTs nitration. Instead, the MWCNTs have been found oxidized by the action of N2O4. By thermogravimetric analysis (TGA) about 5% by weight of oxygenated groups have been found. Thermal analysis has revealed that MWCNTs having a surface area of 275 m2/g are able to reversibly adsorb about 25% by weight of N2O4, a value comparable to that observed for certain active carbons. [ABSTRACT FROM AUTHOR]

Selective oxidation of thiols to disulfides (RSSR) was performed by using catalytic amounts of dinitrogen tetroxide/charcoal in chloroform at r.t. while the reaction of thiols with four molar equivalents of the reagent in dichloromethane afforded thiosulfonates (RSO 2 SR) with excellent yields. [ABSTRACT FROM AUTHOR]

Efficient N -nitrosation of amines, amides, and ureas, and also S -nitrosation of thiols were performed with dinitrogen tetroxide impregnated on activated charcoal (N 2 O 4 /charcoal) in CH 2 Cl 2 at room temperature. High selectivity was observed for N -nitrosation of dialkyl amines, N -alkylamides and N -alkylureas. Dealkylation and N -nitrosation of trialkylamines were also performed by this reagent. [ABSTRACT FROM AUTHOR]

Zn(NO3)2 N2O4 and its charcoal supported system were found to be efficient nitrating agents. Mononitration of aromatic compounds such as benzene, alkyl benzenes, halobenzenes, nitrobenzene, anisol, and the highly selective mono-, di-, and trinitration of phenol, and dinitration of substituted phenols were also performed in the presence of these reagents. [ABSTRACT FROM AUTHOR]

The oxidation of thiols with N2O4 to sulfonic acids is presented. One compound 5b shows lyotropic liquid crystalline properties. [ABSTRACT FROM AUTHOR]

Various hydrazines such as aryl-, carbonyl-, and sulfonyl-hydrazine were reacted with dinitrogen tetroxide to give the corresponding azides in excellent yields under mild conditions at low temperature (−20-−40°C) in acetonitrile. The reaction appears to be initiated by formation of the β-nitroso hydrazine intermediate which converts into the azide product. [ABSTRACT FROM AUTHOR]

A new method of generation of nitrile oxides through interaction of NO with salts of substituted dinitromethanes ( 1) has been worked out. It has been shown byH,C,N NMR spectroscopy that this reaction proceeds via dinitronitrosomethyl intermediates (one of these has been isolated), and that the reaction is feasible only for substituents capable of conjugation with the nitrile oxide fragment. On the basis of cyclodimerization of the obtained nitrile oxides, preparative methods of synthesis of symmetrically substituted furoxans have been developed. [ABSTRACT FROM AUTHOR]