Vol 68, No 10 (2019)

The channels of formation of ester compounds in the liquid-phase oxidation of cyclohexane are reviewed. At least 99.8% cyclohexyl esters of mono- and dicarboxylic acids are formed as a result of cyclohexanol acylation with mixed anhydrides including residues of all compounds with carboxyl groups present in the oxidized cyclohexane. The formation of mixed anhydrides is related to the fast reacylation of adipic anhydride with carboxylic acids. Alcoholysis of mixed anhydrides containing the formic acid residue with cyclohexanol leads mainly to cyclohexyl formate. The formation of ε-caprolactone during cyclohexane oxidation is the result of the Baeyer–Villiger oxidation of cyclohexanone with peroxy acids through α-hydroxy-α-hydroperoxy ester. A decrease in the yield of ε-caprolactone is reached under the conditions of decomposition or reduction of peroxy acids in the presence the compounds of variable valency metals or sulfur-containing reagents, respectively. The cobalt(II) and manganese(II) compounds stimulate the homolytic decomposition of α-hydroxy-α-hydroperoxy ester during which no lactone is formed. The cyclization of 5-hydroxypentanoic acid, which was formed by the oxidative transformations of cyclohexanone, leads to δ-valerolactone. The compounds of variable valency metals slightly affect the yield of δ-valerolactone. The mechanism of ester formation associated with the acylation of oxiranes formed by the radical chain oxidation of carbonyl compounds at the β-CH bonds was proposed.

A microporous carbon adsorbent MPU-007 with a wide pore size distribution (specific micropore volume W₀ calculated within the framework of the theory of micropore volume filling is 1.44 cm³ g⁻¹; first-mode micropore diameter X₀₁ is 1.5 nm; second-mode micropore diameter X₀₂ is 3.5 nm; specific surface area S_BET is 2520 m² g⁻¹) was prepared by chemical activation of a mixture of corn dextrin, ethylene glycol, and phenol formaldehyde resin. Adsorption of ethane on this adsorbent was studied at pressures up to 4 MPa at T = 303, 313, 323, and 333 K. The maximum ethane adsorption value attained in the experiments was 25 mmol g⁻¹ or 75 wt%. The adsorption isosteres plotted in the ln P–1/T coordinates using the data obtained can be well approximated by linear functions at constant adsorption values. The dependences of the differential molar isosteric heats of adsorption of ethane on MPU-007 on the amount adsorbed in the temperature range of 303–333 K were calculated. The heat of adsorption of ethane equal to 23 kJ mol⁻¹ remained constant throughout the initial range of micropore fillings up to ∼7 mmol g⁻¹ and then gradually decreased to 8 kJ mol⁻¹ at an uptake of 24 mmol g⁻¹ at 333 K. Such a pattern of the dependence of the heat of adsorption can be due to a wide pore size distribution and to the formation of associates in the adsorbate.

The applicability of 1,4-diethynylbenzene (DEB) as a dispersant of solid fuels was studied. The atmospheric flight ranges of an aircraft with a rocket ramjet engine operating on fuels with DEB dispersant and wth high-enthalpy dispersants containing not only carbon and hydrogen, but also nitrogen and oxygen, were compared. Fuels with DEB are much more efficient in terms of this performance characteristic. The regularities of gasification of solid propellants comprising DEB, a binder, and ammonium perchlorate were studied experimentally. 1,4-Diethynylbenzene containing no oxidizing elements in the molecule can burn by itself due to the high enthalpy of formation (ΔH°_f) in the 2–6 MPa pressure range. The dependences of the combustion rate on the pressure and on binder and ammonium perchlorate contents were elucidated.

The article is concerned with the influence of resonance donor substituents R_D on the dipole moments μ of molecules 1,4-R_DC₆H₄R_A containing resonance acceptor groups R_A (CF₃, CN, COCH₃, NO₂ or COH) and grouped in five reaction (indicator) series. Generally, the μ values depend on the inductive, resonance, and polarizability effects of the substituents R_D. Strengthening of the resonance acceptor properties of the R_A groups leads to weaker conjugation between the substituents R_D and the π-system.

A transition-metal-free method of cyclopropanation of sterically hindered olefins, substituted allylic alcohols, allylamines, and vinyl silyl ethers was developed using diazomethane in the presence of organic aluminum halides.

A new synthesis of phthalaldehyde that avoided formation of HBr involved treatment of 1,2-bis(dibromomethyl)benzene with trimethyl orthoformate (1: 6, 90 °C, 10 mol.% ZnCl₂) to obtain acyclic diacetal without admixture of cyclic one (1,3-dimethoxy-1,3-dihydrobenzo-[c]furan) followed by hydrolysis to give the target dialdehyde. Phthalaldehyde reacted with CH(OMe)₃ in the presence of trifluoroacetic acid to yield exclusively cyclic diacetal. Acyclic diacetal was phosphorylated by treatment with secondary chlorophosphines and by the reaction with PCl₃ followed by treatment with P^III acid ester.

The main route of a new reaction of (dichloromethyl)arenes with S-methyl diethylthiophosphinate is the attack of the thiol sulfur atom (P–SMe) on the methylene carbon atom. A new method for synthesizing dimethyl dithioacetals of arenecarbaldehydes without using highly toxic methanethiol was developed. The suggested approach involves di(dechloromethylthioylation) of the dichloromethyl group of (dichloromethyl)arenes with S-methyl diethylthiophosphinate at a reagent ratio of 1: 2.

The formation of new polymeric nanocomposites with silver nanoparticles incorporated into the matrix of 1-vinyl-1,2,4-triazole copolymers with vinyl acetate was studied. Water-soluble nanocomposites containing different amounts of silver nanoparticles with an average size of 6–13 nm were synthesized varying the reaction conditions. The physicochemical, optical, thermal, and structural properties of the nanocomposites were studied by IR and UV spectroscopy, transmission electron microscopy, X-ray diffraction and atomic absorption analyses, and thermogravimetry. The antimicrobial activity of the initial copolymers and related nanocomposites was evaluated with respect to test microorganisms.

New 4-dimethylamino-2-(naphthalen-1-yl)-1-phenyl-1-(quinolin-3-yl)butan-2-ols with antituberculosis activity were synthesized. (1R*,2S*)-1-(6-Bromo-2-chloroquinolin-3-yl)-4-dimethylamino-2-(naphthalen-1-yl)-1-phenylbutan-2-ol hydrocitrate exhibiting high antituberculosis activity is in the final stage of clinical trials and is prepared for use in clinical practice.

The possibility of improving the solubility of drugs by obtaining solid dispersions (SDs) with polymers is demonstrated. The solubility of these SDs is dependent both on the nature of drug and polymer and on the conditions of their preparation. IR spectroscopy of the obtained SDs and the analysis of results found in literature indicate that inclusion complexes are formed within them.

Pentachloropentadienic acid was isolated, apart from the expected 5,5-dimetoxytetrachlorocyclopentadiene, in the reaction of hexachlorocyclopentadiene with potassium hydroxide in methanol. The structure of this minor product was established by X-ray crystallography. The plausible mechanism of its formation is discussed.