New N-nitrosoamines. 2. Transformations of tetrahydro-1,3-oxazines into nitrates of N-nitrosoamino alcohols

The reactions of HNO₃ with tetrahydro-1,3-oxazines 1a—c produced by aminomethylation of diketopiperazine, isatin, and succinimide, respectively, afforded nitrates of amino alcohols [RCH₂NH₂(CH₂)₃ONO₂]⁺NO₃ ^– (4a—c) whose subsequent N-nitrosation (NaNO₂, AcOH) gave nitrates of N-nitrosoamino alcohols RCH₂N(NO)(CH₂)₃ONO₂ (5a—c). The structures of compound 5b,c were established by X-ray diffraction analysis.     

Dielectric properties of a magnetized electron gas in a nanotube

A quantum expression is derived for the longitudinal permittivity of a magnetized electron gas in a quantum cylinder. The asymptotics of the dispersion law are calculated for longitudinal plasma waves in a degenerate electron gas. The approximations of the weak and strong spatial dispersions are considered. It is shown that the longitudinal permittivity is an oscillating function of the magnetic flux through the cross section of the nanotube.     

Preparation of quaternary ammonium salts with a perhydroimidazo[1,5-c]oxazolium molecular skeleton

Russian Chemical Bulletin -     

Effect of an external magnetic field on Landau damping in carbon nanotubes

A quantum-mechanical formula for describing the dependence of the longitudinal permittivity of a nanotube on its characteristic parameters and the magnetic field strength was derived. The imaginary part of the permittivity was isolated, and the cases of a Boltzmann and degenerate electron gas were examined. For a degenerate electron gas, asymptotic expressions for absorption in the short- and long-wave ranges were obtained. It was demonstrated that the absorption coefficient for a longitudinal electromagnetic wave exhibits Aharonov-Bohm oscillations.     

Transformations of nitrates (nitro esters) of amino alcohols involving both functions. 1. Reaction with alkali metal hydrogen carbonates

The reaction of nitrates (nitro esters) of amino alcohols with alkali metal hydrogen carbonates yielding oxazolidin-2-ones and tetrahydro-1,3-oxazin-2-ones was discovered. A large number of both known and newly synthesized nitrates of amino alcohols with various structures were involved in this reaction, and the optimum reaction conditions were found. New oxazolidin-2-ones and tetrahydro-1,3-oxazin-2-ones were synthesized. Two more transformations were found for a few examples. One of the reactions gives nitramino alcohols, whereas another reaction affords polymers.     

N-substituted tetrahydro-1,3-oxazines and -oxazolidines. 2. Nitration of <Emphasis Type="Italic">N</Emphasis>-(ω-acylamino-β,β-dinitroalkyl)tetrahydro-1,3-oxazines and -oxazolidines

Nitration of N-(ω-acylamino0-β,β-dinitroalkyl)tetrahydro-1,3-oxazines and N-(ω-acylamino-β,β-dinitroalkyl)oxazolidines resulted in O-nitrates bearing amide, dinitromethylene, and nitroamine groups. It was found that nitration can be accompanied by N-hydroxymethylation of the amide group. Three nitrates synthesized were tested for, and exhibited good level of, cardioprotection.     

Ion transport in MF-4SK membranes modified with hydrous zirconium hydrogen phosphate

Composites based on perfluorinated cation-exchange membranes MF-4SK with embedded zirconium hydrogen phosphate were synthesized using various precursors. Physicochemical interfacial interactions were discovered. The composites have higher proton conductivity and another diffusion permeability than unmodified MF-4SK membranes.     

The stability in a strict non-linear sense of a trivial relative equilibrium position in the classical and generalized versions of Sitnikov's problem

Stability, in a strict non-linear sense, of a trivial relative equilibrium position is investigated in the classical and generalized versions of Sitnikov's problem in the case of small eccentricities of the orbits of bodies of finite dimensions. In the classical version (n = 2) of the problem, it is proved that there are no second-, third- and fourth-order resonances and a degenerate case. In the generalized version (2 < n ≤ 5 · 10⁵), it is proved that there are no second- and third-order resonances and a degenerate case. A fourth-order resonance occurs in versions of the problem in which the number of finite size bodies satisfies the inequality 45000 ≤ n ≤ 62597 and the orbital eccentricities e < 0.25. Use of the Arnold–Moser and Markeyev theorems enables one to establish the Lyapunov stability of the trivial positions of relative equilibrium in the above-mentioned versions of Sitnikov's problem.