Vol 88, No 2 (2018)

Thermal decomposition of peroxydecanoic acid has been investigated in various organic solvents. The reaction medium significantly affects the rate of peroxydecanoic acid thermal decomposition. It has been shown that primary homolytic decomposition of peroxy group is followed by induced radical chain decomposition reactions. The solvent nature influences both primary homolytic decomposition and secondary induced reactions. The correlation equations relating kinetic parameters of peroxydecanoic acid thermolysis and basic solvent properties have been derived.

Hydrogenation of acetophenone and esters of ketoacids with molecular hydrogen in the presence of the Pd(acac)₂–(–)-cinchonidine–H₂ catalytic system has been studied. The dependence of the molar ratio of (–)-cinchonidine/Pd on size and shape of palladium nanoparticles, formed in the system, also on reaction rate and enantioselectivity has been established. The nature of the regularities observed for the Pd(acac)₂–(–)-cinchonidine–H₂ catalytic system was discussed.

Addition of 1-substituted tetrazole-5-thiols to ethyl propiolate and phenylacetylene was studied. It was found that Pd(II) salts in the presence of strong acids are effective catalysts for this reaction: the S-adducts can be obtained at relatively low temperatures in high yields. The mechanism of this reaction was suggested.

Alkylation of fluorophenols and phenolic aldehydes with 5-phenyl(p-tolyl)-3-chloromethylisoxazole under the Williamson reaction conditions afforded the corresponding ethers. Condensation of the resulting phenolic aldehyde derivatives and 5-phenyl(p-tolyl)isoxazole-3-carbaldehydes with p-fluoroaniline resulted in fluorine-containing azomethines. Acylation of fluorinated amines with 5-(p-tolyl)isoxazole- and 4,5- dichloroisothiazole-3-carbonyl chlorides gave rise to fluorinated amides bearing isoxazole and isothiazole fragments, representatives of which showed a synergistic effect in compositions with insecticides.

A method for the synthesis of N-(4-alkyl, alkoxyphenyl)amides and imidoamides of maleopimaric acid was developed. Their thermal stability and optical activity were estimated. The properties of liquid crystal compositions with the synthesized compounds as chiral dopants were studied.

Novel Cu(II), Co(II), Ni(II), and Zn(II) complexes of 5-methyl-2-phenyl-4-[(4-phenylazo)anilinemethylylidene]- 2,4-dihydro-3H-pyrazole-3-thione and 5-methyl-4-[4-methyl-2-(4-methylphenylazo)anilinemethylylidene]- 2-phenyl-2,4-dihydro-3H-pyrazole-3-thione, i.e. ligands containing the phenylazo group in the ortho and para positions of the aniline fragment, were synthesized by the chemical and electrochemical methods. The complexes and ligands were characterized by IR, ¹H NMR, X-ray absorption spectroscopy and magnetochemistry. The azo group of the ligands is not involved in coordination to the metal.

The influence of the structure of diimine bridge in the Schiff’s bases (derivatives of N,N'-ethylenebissalicylimine) on the rate of the loss of electroactivity of their complexes with nickel in acetonitrile containing 0.1 M of tetraethylammonium tetrafluoroborate (anhydrous and upon addition of 1 wt % of water) has been studied. It has been shown that the presence of bulky yet light methyl groups in the structure of diimine bridge significantly reduced the loss of electroactivity (37% of the initial capacity retained after 50 cycles) as compared to the ligand containing no substituents and containing phenyl group as the substituent (17 and 20%, respectively, of initial capacity retained after 50 cycles).

Nickel nanoparticles were synthesized by the reduction of its salts by hydrazine hydrate in a polyol medium in the presence of sodium polyacrylates with molecular weights of 1200, 5100, and 8000. The nanoparticles were characterized by X-ray diffraction, scanning and transmission electron microscopy, IR spectroscopy, and thermogravimetric analysis. The effect of the synthesis conditions, such as temperature, molecular weight of sodium polyacrylate, and polyol and precursor types, on the reduction products were studied. It was shown that the average particle sizes, their aggregation and polydispersity degrees increase as the polymer molecular weight increases.

In this study two different methods without a catalyst and with a CeO₂ nano catalyst were used for the synthesis of dimeric disulfide-Schiff bases. The dimeric disulfide-Schiff base derivatives were characterized by FT-IR, NMR, and MS spectra, and elemental analysis. The disulfide-Schiff bases and their derivatives 2–5c were screened for in vitro antibacterial activity against 40 multidrug-resistant strains of Acinetobacter baumannii, and their minimum inhibitory concentrations were determined. Most of products exhibited high antibacterial activity against Acinetobacter baumannii.

By using K₂[Ni(CN)₄] as a building block and two Mn(III) compounds containing bicompartimental Schiff-base ligands as assembling segments, two new cyanide-bridged Ni–Mn complexes of the formula {[Mn(L¹)(H₂O)]₄[Ni(CN)₄]}[ClO₄]₂·2CH₃CN (1) and {[Mn(L²)(H₂O)]₂[Ni(CN)₄]}·CH₃CN H₂O (2) (L¹ = N,N’-1,2-propylene-bis(3-methoxysalicylideneiminate; L² = N,N’-1,2-propylene-bis(3-ethoxysalicylideneiminate) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray analysis. Single Xray diffraction analysis revealed the cationic pentanuclear and neutral trinuclear structures for complexes 1 and 2, respectively, and indicated that the structure of the Schiff-base ligand had obvious influence on the structural types of the target cyanide-bridged complexes. Both cyanide-bridged complexes are self-complementary via coordinated aqua ligand from one complex and the free O₄ compartment from the neighboring complex, therefore giving supramolecular two-dimensional network and one-dimensional zig-zag chain structure. Study of magnetic properties revealed weak antiferromagnetic coupling within the Mn₂ dimer formed by the intermolecular hydrogen bond.

The efficiency of the hydroacoustic impact produced by a rotor-stator device for intensification of the chitin deacetylation process was studied. Preliminary mechanical activation of an aqueous suspension of chitin was found to decrease the reaction time more than by half and strongly decrease the molecular weight loss of the polymer.

The published data on the preparation of cellulose nitrate are summarized. New sources of cellulosic materials are analyzed. The results of studies on the chemical modification of cellulose nitrate by nucleophilic substitution are presented. The published data on the plasticization of cellulose nitrate are summarized. Modern plasticizing systems and methods for their effectiveness assessment are described.

Dehydrobromination of 2-(1,2-dibromoethyl)-1,3-dioxocyclanes with sodium amide in liquid ammonia provided cyclic acetals of propargyl aldehyde. Reactions of the resulting compounds with nitrile oxides and diazomethane afforded the corresponding isoxazole and pyrazole derivatives.

2-Aryl-5-(2,6-dimethoxyphenyl)-1H-1,3,4-oxadiazoles were synthesized by cyclization reaction of benzoylbenzohydrazides in SOCl₂, and their spectral luminescent properties were studied. The oxadiazoles containing phenyl or o-methoxyphenyl substituents in the position 2 were shown to luminesce with a high quantum yield in polar and nonpolar solvents. The replacement of these substituents by 2-hydroxyphenyl group led to oxadiazole intensely emitting only in highly polar aprotic DMSO.

Conditions were determined for the synthesis of TiO₂ mesoporous thin films on silicon by the solgel method in the version of coating by dipping silicon plates in a TiO₂ sol (dip-coating).