One-Pot and Two-Chamber Methodologies for Using Acetylene Surrogates in the Synthesis of Pyridazines and Their D-Labeled Derivatives

Acetylene surrogates are efficient tools in modern organic chemistry with largely unexplored potential in the construction of heterocyclic cores. Two novel synthetic paths to 3,6-disubstituted pyridazines were proposed using readily available acetylene surrogates through flexible C₂ unit installation procedures in a common reaction space mode (one-pot) and distributed reaction space mode (two-chamber): (1) an interaction of 1,2,4,5-tetrazine and its acceptor-functionalized derivatives with a CaC₂−H₂O mixture performed in a two-chamber reactor led to the corresponding pyridazines in quantitative yields; (2) [4+2] cycloaddition of 1,2,4,5-tetrazines to benzyl vinyl ether can be considered a universal synthetic path to a wide range of pyridazines. Replacing water with D₂O and vinyl ether with its trideuterated analog in the developed procedures, a range of 4,5-dideuteropyridazines of 95–99% deuteration degree was synthesized for the first time. Quantum chemical modeling allowed to quantify the substituent effect in both synthetic pathways.     

Thermal stability of the extraction system “TODGA in Isopar M with n-decanol” at above atmospheric pressure

Journal of Thermal Analysis and Calorimetry - The gas evolution dynamics has been studied during thermal oxidation of 0.15 and 0.2 mol L?1 solutions of...     

Structure of the polymer chain of poly(1,3-pentadiene) synthesized using a stereospecific catalytic system

Russian Chemical Bulletin - The structure of polymer chain of poly(1,3-pentadiene) synthesized via a stereospecific polymerization catalyzed by a system based on neodymium trichloride was...     

One-dimensional beam ordering of protons in a storage ring

The ordering of protons has been observed at a new storage ring, S-LSR, at Kyoto University. Abrupt jumps in the momentum spread and the Schottky noise power were observed for protons for the first time at a particle number of approximately 2000, upon applying electron cooling with electron currents of 25, 50, and 100 mA. The transition temperature was 0.17 and 1 meV in the longitudinal and transverse directions, respectively. The transverse temperature of the proton beam was much below that of electrons at the transition, which played an essential role in the ordering of protons.     

Low-temperature plasticity in nanocrystalline titanium and copper

The stress-strain compressive curves, temperature dependences of the yield stress, and small-inelastic-strain rate spectra of coarse-grained and ultrafine-grained (produced by equal-channel angular pressing) titanium and copper are compared in the temperature range 4.2–300 K. As the temperature decreases, copper undergoes mainly strain hardening and titanium undergoes thermal hardening. The temperature dependences of the yield stress of titanium and copper have specific features which correlate with the behavior of their small-inelastic-strain rate spectra. Under the same loading conditions, the rate of microplastic deformation of ultrafine-grained titanium is lower than that of coarse-grained titanium and the rate peaks shift toward high temperatures. The deformation activation volumes of titanium samples differing in terms of their grain size are (10–35)b ³, where b is the Burgers vector magnitude. The dependences of the yield stress on the grain size at various temperatures are satisfactorily described by the Hall-Petch relation.     

Metastable modifications in mercury diiodide nanocrystals

The formation of the HgI₂ crystalline phase in pores of various porous matrices and on their surfaces was studied. Based on the analysis of the evolution of the HgI₂ optical spectra and electron and atomicforce microscopy data, it was shown that the formation of microcrystals of the stable red α modification is preceded by the formation and growth of particles of metastable yellow (β′) and orange modifications. The absorption edge of the β′ phase at T = 77 K is formed by excitonic transitions with an energy of ～2.7 eV. The Raman spectra of the β′ phase were compared to the spectra of known metastable yellow modifications.     

Fixed index gratings in LiNbO(3):Fe upon long-term exposure to an intense laser beam

Permanently fixed noisily recorded refractive index gratings are discovered in single crystals of LiNbO(3):Fe upon long-term exposure to a single laser beam with high intensities of I=100 kW/m(2) and ambient temperature. The fixing process is explained by considering the effect of laser-induced heating of the sample and the well-known simultaneous thermal fixing procedure.     

Synthesis and characterization of nanoparticles with an iron oxide magnetic core and a biologically active trialkylsilylated aliphatic alkanolamine shell

Water-soluble double-coated magnetic nanoparticles (NPs) containing cytotoxic decyldimethyl(β$\beta$-dimethylaminoethoxy)silane methiodide (AA) molecule sorbed at biocompatible magnetic particles, which consist of magnetite pre-coated with oleic acid (OA), have been prepared. X-ray line profile broadening analysis was used for crystallite size determination. The method of magnetogranulometry has been used for determination of diameter of iron oxide magnetic core and magnetic properties of NPs prepared. In vitro cytotoxicity on monolayer tumor cell lines HT-1080 (human fibrosarcoma), MG-22A (mouse hepatoma) and normal mouse fibroblasts (NIH 3T3) has been studied. It was revealed that all the water-based colloidal solutions obtained are non-toxic and possess high NO-induction ability.     

Study of the feasibility of distributed cathodic arc as a plasma source for development of the technology for plasma separation of SNF and radioactive wastes

One of the key problems in the development of plasma separation technology is designing a plasma source which uses condensed spent nuclear fuel (SNF) or nuclear wastes as a raw material. This paper covers the experimental study of the evaporation and ionization of model materials (gadolinium, niobium oxide, and titanium oxide). For these purposes, a vacuum arc with a heated cathode on the studied material was initiated and its parameters in different regimes were studied. During the experiment, the cathode temperature, arc current, arc voltage, and plasma radiation spectra were measured, and also probe measurements were carried out. It was found that the increase in the cathode heating power leads to the decrease in the arc voltage (to 3 V). This fact makes it possible to reduce the electron energy and achieve singly ionized plasma with a high degree of ionization to fulfill one of the requirements for plasma separation of SNF. This finding is supported by the analysis of the plasma radiation spectrum and the results of the probe diagnostics.     

Comparative analysis of structural parameters of the nearest surrounding of nitrate and perchlorate ions in aqueous solutions of electrolytes

Data on structural parameters of the nearest surrounding of nitrate and perchlorate ions in aqueous solutions under standard conditions have been generalized. Hydration numbers, interparticle distances, and ionic association types have been discussed and compared. The major difference between the ions is that nitrate ion tends to form ion pairs, whereas perchlorate ion does not.