Vol 65, No 4 (2016)

Data on methods of synthesis and reactivity of α-diazomethylphosphonic acid esters are classified. Main approaches to obtain diazomethylphosphonate ester (the Seyferth—Gilbert reagent) as well as α-substituted diazomethylphosphonates are considered. The most important reactions of α-diazomethylphosphonates are discussed: [1+2] cycloaddition to alkenes, insertion into heteroatom—heteroatom bonds, reactions with aldehydes and ketones, being of interest as preparative methods to obtain cyclopropane phosphonates, α-substituted methylphosphonic esters and alkynes, correspondingly.

The data on the synthesis, properties, reactions, and practical application of tetrazoles with oxygen-, sulfur-, and selenium-containing substituents are systematized. Comparative analysis of structure and reactivity was carried out for the compounds under consideration.

A computer search for new photoactive compounds among indoline spiropyrans of coumarin series was carried out using DFT B3LYP/6-31G(d,p) method. Based on the data obtained, the spiropyrans containing a formylcoumarin fragment annulated to the 2H-pyran ring and possessing photochromic properties were synthesized. The structure and photochromism of these compounds were studied by ¹H NMR, IR, and UV/Vis spectroscopy. The introduction of a formyl group into the coumarin moiety of spiropyrans led to a bathochromic shift of the long wavelength absorption maxima of merocyanine isomers, as well as to a considerable increase in their lifetime.

An analysis of theoretical modeling results of ultrafast kinetics of photoinduced intramolecular charge separation from the second excited singlet state in the dyad Zn-tetraphenylporphyrin-aminonaphthalenediimide (Zn-TPP-ANDI) in a solution of toluene is presented. The calculations are performed within the framework of the stochastic multi-channel model, which includes four electron states (the ground, first and second excited singlet states, the state with charge separation), as well as their vibration sublevels corresponding to the excitation of highfrequency intramolecular vibration modes. A bimodal kinetic curve of population of the state with charge separation observed in experiments is quantitatively reproduced. The absolute yield values of the state with charge separation are determined. The results of the modeling show that intramolecular modes make a significant contribution to the reorganization of low-frequency modes. Quantum chemical calculations were performed, determining the degrees of freedom related to the intramolecular slow motion of nuclei of high amplitude in the dyad Zn-TPPANDI on going from the ground state to the state with charge separation.

The presence of a constant electric field (300 kV m–1) and variation of CO₂ concentration in the fluid affected the morphology of ZnO nanocrystals and the internal structure of ZnO layer obtained on interacting zinc anode with supercritical H₂O/CO₂ at 673 K and 35 MPa. The electric field favors the formation of zinc oxalate and carbonate, the thermal decomposition of which forms the pore structured of ZnO. Moreover, a fraction of elongated nanocrystals in the surface layer of ZnO is increased due to the action of the electric field.

Under the drastic conditions of Zahn—Ochwat cycloacylation of 2-chloroand 2,3-dichlorohydroquinones with dichloromaleic anhydride (a melt of anhydrous AlCl₃ and NaCl, 185—195 °C), the substrates undergo various degrees of disproportionation, which reduces the yields of the target triand tetrachloronaphthazarins. Quantum chemical calculations showed that the cycloacylation in question proceeds as a double aromatic electrophilic substitution of the vicinal protons with the corresponding oxocarbenium ions (acylium cations).

A reaction of N-substituted 5-amino-3-(2-oxopropyl)-1,2,4-thiadiazoles with dimethylformamide dimethyl acetal gave 3-(5-amino-1,2,4-thiadiazol-3-yl)-4-(dimethylamino)but-3en-2-ones, whose cyclization with hydrazine, guanidine, 1H-pyrazol-5-amines and 6-aminopyrimidin-4(3H)-ones led to 3-methyl-1H-pyrazole, 4-methylpyrimidin-2-amine, 5-methyl3-arylpyrazolo[1,5-a]pyrimidines, and 5-methyl-2-R-pyrido[2,3-d]pyrimidin-4(3H)-ones containing a 5-amino-1,2,4-thiadiazole fragment linearly bound at position 3.

Using cationic and anionic polymerization of 1,1,3,3-tetramethyl-2-oxa-1,3-disilacyclopentane (I) and 1,1,3,3-tetramethyl-2-oxa-1,3-disilacyclohexane (II), α,ω-dihydroxypolydimethylsildimethyleneand α,ω-dihydroxypolydimethylsiltrimethylenedimethylsiloxanes (III and IV, respectively) were synthesized. The polymer materials for the flat membranes MI and MII with stable mechanical properties were produced via crosslinking condensation of tetraethoxysilane and the terminal hydroxyl groups of III and IV. Methane and butane were applied to demonstrate the gas transport properties of these membranes. It was shown that compared to PDMS, the synthesized MI and MII have a higher butane/methane ideal selectivity at high permeability coefficients (7800 and 6600 Barrer, respectively). An increase in butane/methane selectivity is achieved due to the high coefficients of butane solubility in the membrane materials.

A synthesis of organosilicon 1,3-benzoxazines (BZ-Si) was accomplished by the reaction of organic phenols, paraformaldehyde and 3-aminopropyl(trialkoxy)silanes, as well as organosilicon phenols of the general formula R´[SiMe₂O]_n[SiMeRO]_mSiMe₂R´ (R´ is 4-hydroxy-3methoxyphenylpropyl-, R is methylor 4-hydroxy-3-methoxyphenylpropyl), paraformaldehyde, and aniline (or monoethanolamine). The structure of BZ-Si was confirmed by NMR and IR spectroscopy. The studies of BZ-Si by DSC showed that the benzoxazine ring opening takes place in the temperature range 130—265 °C. The temperature of 5% mass loss of BZ-Si in air is within 220—270 °C (TGA).

Reactions of CuCl₂ with 1-(N-indolylmethyl)and 1-(N-carbazolylmethyl)silatranes (L) afforded new complexes CuCl2•L. Quantum chemical calculations of these complexes and a Cu^II complex with 1-(N-pyrrolylmethyl)silatrane showed that the Cu atom is coordinated to both the equatorial O atom of the silatranyl group and the π-system of the ligandś heterocycle.

Hybrid thiacalix[4]arene/SiO₂ nanoparticles based on a thiacalixarene derivative containing simultaneously three benzyl and one triethoxysilyl groups at the lower rim and silicon dioxide nanopowder were obtained for the first time. The adsorbing properties of the synthesized hybrid organo-inorganic nanoparticles in relation to aromatic guest molecules (2,4,6trinitrophenol, 2,4-dinitrophenol, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline) were studied in comparison with unmodified silicon dioxide particles.

A procedure of selective bromination of poly(1-trimethylsilyl-1-propyne) using N-bromosuccinimide as the brominating agent was developed. This method allows to obtain samples with different bromine content depending on the process conditions. The obtained brominecontaining polymers have good film-forming properties, satisfactory thermal and thermo-oxidative stability. The introduction of bromine atoms into the polymer increases the stability of the latter to aliphatic hydrocarbons C₅—C₁₂ and improves hydrophobicity. With an increase of bromine content in the polymer, the selectivity of separation of gas pairs CO₂/N₂, CO₂/H₂, and O₂/N₂ increases, while the level of permeability remains high.

A series of novel hybrid porous polymers (HPPs) with high specific surface areas were first prepared by one-step ternary cross-linking copolymerization of octavinylsilsesquioxane (OVS), 1,3,5-tribromobenzene, and 4,4´-dibromoazobenzene via the Heck reaction. The porosities and the CO₂ uptake capacities of resulting azobenzene-doped porous polymers could be tuned by modulating the molar percentage of the azo units. At 273 K and 101 kPa, the sample with the specific surface area of ~700 m² g^–1 (data of Brunauer—Emmett—Teller (BET) surface area analysis) showed the highest CO₂ uptake of 5.45 wt.% (1.20 mmol g^–1) among the fabricated HPPs.

Polyaryleneetherketone (PAEK) based composites obtained by in situ filling method have been investigated. Ethyl silicate, tris-(methyldiethoxysiloxy)iron and tetrakis-(methyldiethoxysiloxy)zirconium were used as the inorganic phase precursors. In the case of the last two precursors, the method of in situ formation of inorganic filler allows to obtain PAEK films containing inorganic nanoparticles, without resorting to the conditions of humidity of the surounding air. This is apparently due to a compatibility of the starting system PAEK—precursor and high reactivity of iron and zirconium methyldiethoxysiloxanes toward hydrolysis. Such filled systems are characterized by high elastic modulus and tensile strength at break, and also lower weight loss in thermo-oxidative degradation compared with the starting polymer.

A simple method for the preparation of the vertically located flexible iron—polysiloxane magnetic needles up to 12 mm long by the self-organization of iron carbonyl microparticles in a solution of thermally cured polydimethylsiloxane rubber in a vertical magnetic field is proposed. The generated structures withstand heating to 300 °С with an appreciable loss of flexibility. Their properties are investigated by scanning electron, atomic force, and optical microscopy.

O,O-Dialkyldithiophosphoric acid reacted with N-tert-butyl-2,2-dihalopropanimines to give iminium salt as a primary product, which further sequentially undergoes reaction with two equivalents of dithiophosphoric acid to initially reduce the C—X (X = Cl, Br) bond in the iminium salt and then nucleophilic replacement of the halogen atom with dialkoxydithiophosphate group. The final reaction products are the reduction—substitution product of the primary salt and bis(dialkoxythiophosphoryl) disulfide.

A quantitative structure-solubility relationship was developed to predict the solubility of some statin drugs in supercritical carbon dioxide (SC-CO₂). The solubility of lovastatin, simvastatin, atorvastatin, rosuvastatin, and flovastatin in SC-CO₂ at 225 different states of temperature and pressure were predicted. Classification and regression tree (CART) was successfully used as a descriptor selection method. Three descriptors (pressure, temperature, and molecular weight) were selected and used as inputs for adaptive neuro-fuzzy inference system (ANFIS). The root mean square errors for the calibration, prediction, and validation sets were 0.09, 0.14, and 0.11, respectively. In comparison with other methods, CART-ANFIS is a powerful model for prediction of solubilities of these statins in SC-CO₂.

A series of organosilicon rubbers of the addition-curable type containing dimethyland methylphenylsiloxy, or diphenylsiloxy units with terminal vinyl groups were synthesized and used for manufacturing liquid silicone rubbers (LSRs) by addition-curable vulcanization. The physical mechanical characteristics of the LSRs were studied. The obtained LSRs can find use at lower temperatures, since they have low glass transition temperatures, and dimethylsiloxane component crystallization is suppressed in them.

The volatile constituents of the leaves of Digitalis nervosa Steud. & Hochst. ex Benth. growing wild in Iran was reported for the first time. The essential oil of the leaves of this plant was examined by gas chromatography using a flame-ionization detector and gas chromatography coupled with mass spectrometry. Thirty-four components were identified constituting approximately 96.5% of the essential oil of D. nervosa. The essential oil of D. nervosa is rich in palmitic acid (20.5%), trans-pinocamphone (16.0%), phytol (6.5%), caryophyllen oxide (5.9%), hexahydrofarnesyl acetone (4.6%), 3-ethyl-4-methyl-1-pentanol (4.4%), oleic acid (3.7%), spathulenol (3.6%), di(2-methylpropyl) phthalate (2.7%), cedrol (2.3%), and farnesol (2.1%). The results obtained showed that the essential oil of D. nervosa contains ten oxygenated monoterpenes (25.7%), seven oxygenated sesquiterpenes (21.1%), one oxygenated diterpene (6.5%), and fourteen nonterpene (41.4%) compounds. The essential oil from the D. nervosa leaves has relatively high content of the oxygenated monoterpenes, therefore a significant antibacterial role for this essential oil is expectable. Because of the presence of trans-pinocamphone, which can act as a γ-aminobutyric acid (GABA)-gated chloride channel blocker, the essential oil of D. nervosa can be neurotoxic.