Russian Chemical Bulletin最新文献

A series of new thermosetting diimides containing terminal propargyl groups was synthesized via one-step high-temperature catalytic condensation of dianhydrides of a tetracarboxylic acid with N-Boc-(4-propargyloxy)aniline (APR) in the so-called “active medium”, viz. molten benzoic acid. Structures of the obtained compounds were confirmed by ¹H NMR and IR spectroscopy. The effect of symmetrical and unsymmetrical structures of the middle bis-imide moiety obtained from dianhydrides of isomeric diphenyltetracarboxylic acid on physicochemical characteristics of the diimides was evaluated. A similar comparison of properties was also carried out for a pair of new propargyl-containing diimides synthesized from dianhydrides of symmetric and asymmetric structure: 4,4-biphenylenedioxydiphthalic and 3,4-biphenylenedioxydiphthalic dianhydrides, respectively. Thermal properties of thermosetting oligoimides were estimated using DSC and TMA methods. It was found that their thermal properties and solubility in organic solvents depend significantly on the structure of central bis-imide moiety.

Redox processes in the polymer film of poly-N,N′-ethylenebis(3-methoxysalicylideneimine were studied for the first time by in situ methods including electron spin resonance spectroscopy, ultraviolet—visible—near-infrared spectroscopy, and Fourier transform infrared spectroscopy. The integration of the obtained data with the results of electrochemical nanomechanical atomic force microscopy measurements allowed us to determine causes of a low electrochemical oxidative polymerization efficiency of this compound and a rapid loss of its electrochemical activity in the oxidation—reduction processes.

A simple method was developed for the synthesis of a new heterocyclic ensemble composed of the consecutively connected 1,2,5-oxadiazole, tetrazole, and hydroxytetrazole rings. The structure of ammonium salt of this ensemble was studied by X-ray diffraction.

A one-step synthesis of 5-isothiocyanato-6-methyluracil from the corresponding hydroxamic acid was carried out. A plausible mechanism of the reaction was proposed.

A series of new oligoimides based on 4,4- and 3,4-oxydianiline and 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, possessing different average chain lengths, and containing terminal propargyl groups were synthesized according to an efficient single-step high-temperature polycyclocondensation method. Their molecular weight characteristics, solubility in organic solvents, thermal (DSC, TMA, and TGA), and rheological properties were studied. The synthesized oligoimides exhibited a significantly lower exothermic effect upon curing due to their elongated chain as compared to diimides. The oligoimides upon increasing the temperature enter into a viscous fluid state, in which they remain up to the curing onset temperature of 270–320 °C. The symmetry of structure of the diamine moiety (4,4-ODA or 3,4-ODA) and the molecular weight of oligoimides affect the temperature of transition to the viscous fluid state.

A new approach to the alkylation of azoles with alkenes catalyzed by the nickel complexes with N-heterocyclic carbenes (Ni/NHC) was developed. The catalytically active Ni/NHC complexes are formed in situ from the air-stable precursors: the nickel chloride complex with pyridine (NiCl₂Py₂), imidazolium salt IMes•HCl (IMes is 1,3-bis(2,4,6-trimethylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene) as the carbene source, and sodium tert-butoxide (Bu^tONa). The advantages of the developed approach are availability of the components of the catalytic system, no necessity to apply special agents for the reduction of Ni^II to Ni⁰, and simplification of the synthesis procedure.

The synthesis of a new symmetric bis(spiropyran) of the indoline series existing as an equilibrium mixture of isomeric forms in various organic solvents is described. This equilibrium was in detail studied by dynamic NMR spectroscopy. In particular, the equilibrium constants were found at various temperatures, and the thermal effects of isomerization processes were calculated. The thermal transformations were studied by quantum chemical modeling. As a result, possible isomerization pathways were proposed and the observed ratio of the forms in the NMR spectra was explained. Photo- and thermochromic transformations were studied by UV spectroscopy, which revealed positive photochromic properties of the target compound. The observed changes in the absorption spectra with increasing temperature are completely consistent with the results of NMR studies. The nature of the absorption bands observed in the spectra was explained using time-dependent density functional theory (TD-DFT) calculations. The surface-enhanced Raman scattering (SERS) spectra of the synthesized compound on the surface of silver nanoparticles were detected and analyzed before and after UV irradiation to determine prospects for using similar bis(spiropyrans) as SERS markers and probes.

A special setup was assembled to study solvent adsorption by metal organic frameworks (MOFs). A blank test was run to examine the noise level and the kinetic desorption curves for solvent molecules under different carrier gas (N₂) flow rates were measured with the instrument error lying within a limited range. The desorption process could be adequately characterized by the transport of adsorbates in pores within MOFs. For the MOF samples NH₂-MIL-101(Fe), HKUST-1, MIL-101(Cr), ZiF-67, and ZIF-8, the intercrystalline diffusion coefficient of ethanol, toluene, and propan-2-ol at 25, 35, and 45 °C were calculated and the activation energy was evaluated. The diffusion data obtained are in agreement with those reported earlier.

A key goal of organic chemistry is to develop new principles for the control of reactions, which can be used to create promising materials demanded in all fields of scientific research and industry. This review is an overview of the scientific advances, which have been made by the N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences in the past decade within the framework of current trends in organic chemistry. The review covers the results, which are significant for fundamental research and hold great promise for the application in different areas, from the production of materials, petrochemistry, and chemical ecology to medicine, agriculture, and food industry.