Vol 67, No 11 (2018)

The research towards the development of new propellants aims to ensure not only their high performance, but also high environmental compatibility and low toxicity. Considerable attention is paid to the development of hypergolic propellant compositions, the use of which markedly simplifies the engine design and rocket system operation and provides the possibility of their repeated use. Hydrogen peroxide is a promising and nontoxic oxidant. The review summarizes the research and development data concerning the design and application of hypergolic rocket propellants involving hydrogen peroxide, starting from the 1930s and up to now. The data presented in the review could be useful for specialists engaged in the development of prospective high-performance green fuels.

Energetic characteristics of electrophilic substitution reactions (hydroxonium ion as a model electrophile) in thiazole via the elimination–addition schemes in a wide range of pH of the medium were revealed on the basis of the results of analysis of quantum chemical calculations performed using the DFT/B3LYP/6-31G(d) and DFT/B3LYP/6-31⁺⁺G(d,p) methods taking into account specific solvation effects.

The vapor–liquid and liquid–liquid phase equilibria in the reaction system of sec-butyl acetate production from n-butenes and acetic acid were simulated. The simulation made it possible to develop two variants of principal technological flowsheets of the process organization. The both variants are based on the principle of redistribution of the concentration fields between the separation regions: in the first case, due to the chemical reaction; in the second case, owing to the splitting phenomenon. The material balances of the schemes were calculated, and the static operating parameters were determined. The first variant of the flowsheet does not enable one to obtain sec-butyl acetate of the required quality and, therefore, heteroazeotropic distillation for the separation of sec-butyl acetate from acetic acid was proposed in the second variant. The use of water as a heteroazeotrope-forming agent in the separation block allows the quality of sec-butyl acetate satisfying the environment standard requirements (GOST) to achieve at technologically appropriate operating parameters.

The influence of a set of additives of various nature on the separation of salbutamol sulfate enantiomers by supercritical fluid chromatography on the stationary phase based on amylose tris(3-chloro-5-methylphenylcarbamate) is considered. The application of water and acidic additives does not lead to enantioseparation. The use of hexafluoroisopropyl alcohol as an additive allows separation to occur but leads to a strong distortion of the chromatographic peaks. The application of basic additives such as isopropylamine or ammonia provides a stable separation with high selectivity and resolution as well as with the symmetrical peak shape. The selectivity coefficient is surprisingly almost independent of the amine modifier concentration in the mobile phase.

A method for synthesizing new compounds capable of releasing NO within living organisms, namely, 2-azidoethyl derivatives of methylenebis(1-oxytriaz-1-ene 2-oxides) bearing one or few 2-azidoethyl moieties, was developed. The synthesis involves nucleophilic substitution of the bromine atoms of the parent 2-bromoethyl derivatives of methylenebis(1-oxytriaz-1-ene 2-oxides) with the azide group. Some of the synthesized compounds are of interest as promising energetic materials.

New diphenylsulfimide derivatives containing substituents with the 2,6-di-tert-butylphenol moiety at the nitrogen atom were synthesized. Their molecular structures were established by X-ray diffraction. Antioxidant activity was experimentally evaluated by spectrophotometry based on hydrogen transfer to the stable radicals, namely, 2,2-diphenyl-1-picrylhydrazyl and the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS^·+), and using in vitro lipid peroxidation in rat brain and liver homogenates. The presence of phenol and diphenylsulfimide moieties in one molecule leads to a significant enhancement of antioxidant activity. The new compounds exhibit moderate inhibitory activity against enzymes involved in carbohydrate and lipid metabolism. The evaluation of antiglycation activity showed that the new sulfimides taken at a concentration of 100 μmol L^–1 have activity comparable with that of aminoguanidine.

The oxidation of hexane-2,3,4,5-tetraone tetraoxime with dinitrogen tetroxide was studied in different solvents. The primary furoxan ring closure was found to occur involving either two central or two terminal oxime groups to form 4,7-dimethyl[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide and the previously unknown 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide. The structure of the latter compound was established by X-ray diffraction.

Reaction of 3-thiocarbamoylchromones with hydrazines is accompanied by recyclization affording 2-aminochromone-3-carbaldehyde hydrazones.

The energetic potential of solid composite propellants (SCP) with furazano[3,4-e]di([1,2,4]- triazolo)[4,3-a:3′,4′-c]pyrazine including trinitromethyl (C(NO₂)₃), fluorodinitromethyl (CF(NO₂)₂), and (difluoroamino)dinitromethyl (C(NF₂)(NO₂)₂) groups was estimated based on thermochemical calculations. It was shown that C(NO₂)₃ and C(NF₂)(NO₂)₂ derivatives can constitute the basis of metal-free compositions of SCP with a specific impulse from 251 to 263 s, i.e., comparable or superior in efficiency to HMX-based propellants.

The reaction of azoloannulated [1,2,4,5]tetrazines with guanidine was studied. New 3-guanidinoimidazo[1,2-b]- and 6-guanidino[1,2,4]triazolo[4,3-b] [1,2,4,5]tetrazines were synthesized using the nucleophilic substitution methodology. Compounds with high antibacterial and antiglycation activity were revealed.

The synthesis of drug delivery system for pharmaceutical substances, represented by modified shortened single-walled carbon nanotubes, was realized. The synthesis was carried out via covalent grafting of water soluble linker to the graphene surface of single-walled carbon nanotubes, and resulted in stabilization of synthesized substance in water suspension.

The oxidation of the ring A of 16α,17α-cyclohexanoprogesterone gave 5-oxo-A-nor-3,5-secopregnan-3-oic acid. The subsequent ring A closure in the latter compound upon treatment with sodium acetate in Ac₂O afforded 4-oxasteroid. The reaction with ammonium acetate in acetic acid produced 4-azasteroid. Antiproliferative activity of the resulting steroids against cervical cancer HeLa cells and the in vitro binding to the progesterone receptor were studied. The compounds cause a statistically significant decrease in viability of cervical cancer HeLa cells, having no effect on normal skin fibroblasts. The tested steroids show very low binding to the rat uterine progesterone receptor.

The paper considers the influence of the structure of aminoadamantane–carbazole conjugates linked by five different spacers on their ability to inhibit acetylcholinesterase, butyrylcholinesterase (BChE), and carboxylesterase, the radical scavenging and mitoprotective activity, and tubulin polymerization. The nature of the spacer was found to be determinant for the appearance of anti-BChE and radical-scavenging activity. Aminoadamantane–carbazole conjugates linked by flexible spacers proved to be most effective in these assays. The influence of the conjugates on mitochondrial functions and tubulin polymerization largely depends on the structure of the carbazole moiety. A series of lead compounds promising for further study was identified as potential drugs for the treatment of neurodegenerative diseases, in particular, Alzheimer’s disease.

Structure of the O-polysaccharide (O-antigen) of Escherichia coli O60 was studied by sugar analysis, partial solvolysis with CF₃CO₂H, and ¹D and 2D ¹H and ¹³C NMR spectroscopy. The O-polysaccharide was found to consist of D-galactose and L-rhamnose. The structure of its branched tetrasaccharide repeating unit was established, which is unique among known bacterial polysaccharide structures.

Cationic surfactants (S+) and acetylcholine (ACh), the most important neurotransmitter playing an essential role in the neuromuscular and cognitive activity of living beings, form mixed reverse micelles with hydroperoxides (ROOH) in organic media, where ROOH decay into free radicals is catalytically accelerated. Adding cholesterol (Chol, 30 mol.%) to pyridinium (СРВ) and cetyltimethylammonioum (СТАВ) bromides, reduces the radical generation rate in ROOH catalytic decay several times. However, a higher radical initiation rate is observed in the case of less ordered and larger ACh–ROOH reverse micelles. A Chol additive does not essentially affect the size of СТАВ and СРВ micelles with hydroperoxides but results in their decrease in the case of ACh–ROOH.

Earlier, the data on the ability of laminin-332 to protect liver cancer cells from apoptosis caused by doxorubicin, sorafenib, and gefitinib have been obtained. In order to answer the question whether this action of laminins is common for cancer cells of other types, we estimated the effect of several laminin isoforms on the survival of two colorectal cancer cell lines (RKO and SW-480) when treated with chemotherapeutic agents used in the colon cancer therapy (5-fluorouracil, regorafenib, and sorafenib). The data obtained suggest that this action of laminins is not universal and is likely governed by individual features of cancer cells.