Vol 68, No 6 (2019)

The review discusses the results of the authors’ research aimed at the synthesis of stable tetrylenes (germylenes and stannylenes) and the determination of the structure of these compounds, including their oligomeric degree. Substituted dialkanolamines, dialkylenetriamines, aminobisphenols, pyridine and phenanthroline-containing dialcohols, and some other derivatives were used as the ligands for the synthesis. The reactivity of monomeric and dimeric tetrylenes in the reactions proceeding with both the change and the retention of the oxidation state of the metal atom (2+) is discussed in detail, as well as the influence of the oligomeric degree on the reactivity. The use of tetrylenes in synthetically useful reactions as ligands for catalytically active transition metal complexes, as well as initiators for ring-opening polymerization of cyclic esters, is analyzed.

Gold nanoparticles (NPs) were synthesized via chemical (Chem) and radiation-chemical (RadChem) methods for the reduction of ions in reverse micellar solutions (RMS). The gold NP have for the first time been obtained by self-organization (Self-assembly), and their optical properties were evaluated. The formation of Au NP (Chem, RadChem, and Self) was confirmed by the transmission electron microscopy. The spectral characteristics of optical absorption of gold NP in the RMS depend on the solubilization coefficient ω, the salt concentration, and the methods for initiating the primary steps of reduction reactions responsible for the formation of nanoscale structures.

An original method for preparation of nanoparticles with a core—shell structure based on Fe₃O₄ magnetic nanoparticles (MNPs) and iron glycerolate was proposed. The formation of a coating on the MNP surface with a diameter of 11 nm was carried out by heating them in glycerol at 220 °C for 40 h. The synthesized nanoparticles were characterized using scanning transmission electron microscopy, XRD and IR spectroscopy. The amount of glycerol fragments in the nanocomposite calculated from the elemental analysis and TGA was 3.6 mmol per 1 g of MNPs (32.08 wt.%).

The alkylation of 6-(polyfluoro)alkyl-2-thiouracils with 4-bromobutyl acetate in refluxing acetonitrile in the presence of K₂CO₃ proceeds regioselectively to give S, O-disubstituted pyrimidines as the major products and S,N-isomers as the minor ones, whereas the use of 2-bromoacetophenone as an alkylating agent results in the formation of the S,O-isomer. 6-Trifluoromethyl-2-thiouracil and 2-(2-oxo-2-phenylethylthio)-4-(2-oxo-2-phenylethoxy)-6-trifluoromethyl-pyrimidine exhibited marked tuberculostatic activity. 6-Trifluoromethyl-2-thiouracil did not exert a significant cytotoxic effect on the HeLa cell culture and human dermal fibroblasts.

It was demonstrated that nitrosylsulfuric acid can be successfully used as a tandem nitrosating and oxidizing agent in the synthesis of 3,5-diarylisoxazoles from 1,2-diarylcyclopropanes. The reaction proceeds highly regioselectively in the case of symmetric diarylcyclopropanes. The mixtures of regioisomeric 3,5-diarylisoxazoles were obtained from non-symmetric 1,2-diarylcyclopropanes.

New dyes of the 3-[5-(4-alkyl-4H-thieno[3,2-b]indol-2-yl)thiophen-2-yl]-2-cyanoacrylic acid series were prepared based on 2-(thien-2-yl)-substituted thieno[3,2-b]indole by its sequential N-alkylation, formylation, and condensation of the resulting aldehydes with cyanoacetic acid. The possible application of these dyes as sensitizers of mesoporous titanium dioxide thin films in dye-sensitized solar cells (DSSC) was shown. It was established that the efficiency of DSSC based on the dye IS 4 is superior to that of a similar element based on the commercial dye N3 [cis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(ii)].

4-Methyl-7-(4-methyl-2-oxo-2H-chromen-6-yl)disulfanyl-2H-chromen-2-one hydrotriiodide was synthesized by the reaction of 7-mercapto-4-methylcoumarin with iodine, and its structure was determined by NMR spectroscopy and X-ray diffraction combined with Raman and IR spectroscopy. The molecular and crystal structure of the reaction product was determined.

The gas-phase co-pyrolysis of styrene with CHClF₂ in a flow reactor at 550–650 °C gives 2,3-difluoronaphthalene in two parallel reaction channels. The main channel includes decomposition of CHClF₂ to difluorocarbene, whose subsequent cycloaddition to styrene affords 1,1-difluoro-2-phenylcyclopropane. This compound rearranges to 2-fluoroindene giving finally difluoronaphthalene upon the second difluorocarbene cycloaddition and subsequent aromatization of the resulting cycloadduct. The second reaction channel consists in aromatization of 1,1,2,2-tetrafluoro-3-phenylcyclobutane, which is formed by the [2+2]-cycloaddition of styrene to tetrafluoroethylene, a product of difluorocarbene dimerization.

The quasi-homogeneous (“synthesis in gel”) conditions for functionalization of polyvinyl chloride (PVC) with thiourea were experimentally selected. It was found that the best solvent for the formation of PVC gel is DMF, ensuring formation of the gel in the range of polymer concentrations from 10 to 30%. The composition of the products was characterized by elemental analysis data, the specific features of their structure were established by Fourier-transform IR spectroscopy and thermogravimetry. It was shown that thiourea reacted with PVC as an N-nucleophile to form thiocarbamoyl groups in the polymer structure. The maximum achieved total degree of functionalization was 0.31. The reaction was accompanied by cross-linking and partial dehydrochlorination.

A comparative study of the kinetic resolution of racemic derivatives of 3,4-dihydro-3-methyl-2H-[1,4]benzoxazine using racemic 2-aryloxypropionyl chlorides was performed. It was found that the acylation of racemic amines with racemic 2-(1-naphthyloxy)propionyl chloride leads to amides enriched with (3R*,2′R*)-diastereomers, while the acylation with 2-phenoxypropionyl chloride gives predominantly (3R*,2′S*)-amides. Quantum chemical modeling of the process of kinetic resolution at the COSMO-CH₂Cl₂-B3LYP-D3-gCP/def2-TZVP//B3LYP-D3-gCP/def2-SVP level of theory was performed. The computational results are in a good agreement with the experimental data.

Synthesis of 4-(4-cyclohexylphenoxy)-5-nitrophthalonitrile was developed. The method was used for the synthesis of cobalt, zinc, and copper tetra-4-(4-cyclohexylphenoxy)tetra-5-nitrophthalocyanines and their water-soluble analogs.

The influence of the composition of the working mixed acid, mass ratio, and nitration temperature and time on the properties and yield of cellulose nitrates from an unconventional feedstock such as the large-tonnage grain-processing residue, oat hulls, was studied. Experimental statistical models were constructed on the basis of a series of experiments. They enable the properties of cellulose nitrates to be predicted as a function of the mixed acid composition and conditions of the nitration process. The mixed acid composition and the mass ratio of mixed acid to cellulose were found to have the primary effect on the properties of cellulose nitrates, while the nitration temperature and time had no noticeable effect on the final result. Under the optimum synthetic conditions, pilot batches of cellulose nitrates were produced, which corresponded to Colloxiline-N in the main properties: mass fraction of nitrogen was 12.08–12.18%, viscosity was 12–15 mPa s, and the solubility in an alcohol—ether mixture was 98%. The correspondence of the synthesized samples to Colloxiline-N was confirmed by FTIR spectroscopy. The cellulose nitrates derived from the unconventional feedstock may find practical use in manufacturing ballistic powder and composite explosives.

A method for the synthesis of 1,2,4,5,7,8-hexaoxonanes by the reaction of 1,1′-dihydroperoxydi(cycloalkyl)peroxides with acetals using SnCl₄ has been developed. For the first time, it was shown that SnCl₄ can serve as an effective reagent for the synthesis of cyclic organic peroxides. The proposed method allows obtaining 9-membered cyclic triperoxides selectively and in the yields of up to 90% based on the isolated product.

3-Phenylbenzo[c]isoxazoles were synthesized by non-catalytic thermolysis of 2-azidobenzophenones in dry xylene with quantitative yields. The trace content of water in solvents reduces the yields of the reaction products. 2-Azidobenzoic acid esters are stable under the indicated conditions.