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Vol 15, No 5 (2020)
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THEORETICAL BASES OF CHEMICAL TECHNOLOGY

  • The use of evaporating refrigerants considerably intensifies the process of separating the mixture and separating the spent refrigerant from the resulting crystalline suspension.
  • Contact crystallization with evaporating refrigerants can be successfully applied to separate various substances from aqueous solutions.
  • The advantage of this process is the relatively low refrigerant consumption because heat removal from the solution is carried out as a result of changes in the aggregate state of the refrigerant.
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Abstract

Objectives. The aim of this study was to analyze the possibility of using contact crystallization with evaporating refrigerants for the isolation of substances from their aqueous solutions using salts [KNO3, NaI, and (NH2)2CO] as extraction examples and sucrose. Isobutane was used as a refrigerant.

Methods. The analysis of the influence of the main technological parameters (i.e., solution’s cooling temperature, initial concentration, and compressed refrigerant vapor pressure) on the separation process and identification of its regularities was performed using mathematical dependencies previously developed by N.I. Gelperin and G.A. Nosov for each stage of the contact crystallization process. The authors studied the influence of these parameters on the yield of crystalline and liquid phases, refrigerant consumption, and compressor power.

Results. The study showed that the use of evaporating refrigerants can significantly intensify the process of separating the mixture and spent refrigerant from the resulting crystalline suspension. This occurs owing to the evaporation of the liquid refrigerant that is in contact with the solution, which is accompanied by intense cooling. This process can be carried out at the temperature difference between the refrigerant and crystallizing mixture in the range of 0.5–1.0°C.

Conclusions. Contact crystallization with evaporating refrigerants can be successfully applied to separate various substances from aqueous solutions. An important advantage of this process is the relatively low refrigerant consumption because heat removal from the solution is carried out as a result of changes in the aggregate state of the refrigerant. The use of contact crystallization can also considerably simplify the equipment.

CHEMISTRY AND TECHNOLOGY OF ORGANIC SUBSTANCES

  • Alkenyl-gem-dichlorocyclopropanes were synthesized in the presence of triethylbenzyl ammonium chloride as catalyst.
  • Their isomerization and hydrogenation gave the corresponding gem-dichlorocyclopentene and isomers of alkyl-gem-dichlorocyclopropanes.
  • The results show that formation of four isomeric substituted gem-dichlorocyclopropanes occurs in high yield during incomplete dichlorocyclopropanation of piperylene. The thermocatalytic isomerization of substituted gem-dichlorocyclopropanes in the presence of SAPO-34 zeolite leads to the formation of one product, i.e., gem-dichlorocyclopentene, and hydrogenation of substituted gem-dichlorocyclopropanes in the presence of Pd/C catalyst gives three isomeric alkyl-gem-dichlorocyclopropanes.
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Abstract

Objectives. This study aims to obtain alkenyl-gem-dichlorocyclopropanes from piperylene. The products are then subjected to thermocatalytic isomerization and hydrogenation.

Methods. To determine the qualitative and quantitative composition of the reaction crudes, the following analytical methods were used: gas-liquid chromatography using the Crystal 2000 hardware complex, mass spectrometry using a Chromatec-Crystal 5000M device with the NIST 2012 database, and nuclear magnetic resonance (NMR) spectroscopy using a Bruker AM-500 device at operating frequencies of 500 and 125 MHz.

Results. Alkenyl-gem-dichlorocyclopropanes were synthesized in the presence of triethylbenzyl ammonium chloride as catalyst. Their isomerization and hydrogenation gave the corresponding gem-dichlorocyclopentene and isomers of alkyl-gem-dichlorocyclopropanes. The structure of synthesized substances were analyzed by gas-liquid chromatography, mass spectrometry, and NMR spectroscopy.

Conclusions. The results show that formation of four isomeric substituted gemdichlorocyclopropanes occurs in high yield during incomplete dichlorocyclopropanation of piperylene. The thermocatalytic isomerization of substituted gem-dichlorocyclopropanes in the presence of SAPO-34 zeolite leads to the formation of one product, i.e., gem-dichlorocyclopentene, and hydrogenation of substituted gem-dichlorocyclopropanes in the presence of Pd/C catalyst gives three isomeric alkyl-gem-dichlorocyclopropanes.

CHEMISTRY AND TECHNOLOGY OF MEDICINAL COMPOUNDS AND BIOLOGICALLY ACTIVE SUBSTANCES

  • The authors synthesized novel PALA analogs that were derivatives of phosphonacetic acid and studied their biological activities.
  • The obtained compounds’ cytotoxicity was probed in relation to cell lines of human breast cancer (MDA-MB-231), skin cancer (A-375), and glioblastoma (U-87 MG).
  • The compounds synthesized in this work did not display any pronounced anticancer properties. One of the reasons for the observed low activity may be the presence of ether groups in the phosphonate building block.
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Abstract

Objectives. With the development and improvement of new delivery systems for substances of various natures, organophosphorus compounds with an antimetabolic mechanism of action have become relevant again. A few examples of them are organophosphorus analogs of carboxylic acids, such as N-phosphonacetyl-L-aspartate (PALA) and N-phosphonacetyl-L-isoasparagine, both of which are bio-rationally developed analogs of the transition state of carbamoylaspartate in the biosynthesis of pyrimidine bases, which is catalyzed by the enzyme aspartate transcarbamoylase (ATCase). Despite their high activity, these compounds have not found widespread use as anticancer agents due to a large number of side-effects and low bioavailability. Given the emerging opportunities for the delivery of phosphate and phosphonate derivatives into target cells, obtaining more effective analogs of PALA seems to be an interesting and promising research objective. The goal of the present study was thus to synthesize and study the biological activities of novel PALA analogs that are derivatives of phosphonacetic acid.

Methods. For directed work within the framework of the study, we used the molecular docking method, which allowed us to simulate the binding of N-(α-diethoxyphosphorylcyclopropylcarbonyl)- substituted amino acids to ATCase. The target compounds were synthesized using classical methods of organic synthesis. The obtained compounds’ cytotoxicity was probed in relation to cell lines of human breast cancer (MDA-MB-231), skin cancer (A-375), and glioblastoma (U-87 MG).

Results. The synthesis of eight novel N-(α-diethoxyphosphorylcyclopropylcarbonyl)-substituted amino acids was carried out. A few of the synthesized derivatives were tested for anticancer activity, but none displayed significant cytotoxicity.

Conclusions. N-(α-diethoxyphosphorylcyclopropylcarbonyl)-substituted amino acids are synthetically available analogs of PALA, a compound capable of strong interaction with ATCase. However, the compounds synthesized in this work did not display any pronounced anticancer properties. One of the reasons for the observed low activity may be the presence of ether groups in the phosphonate building block.

  • A synthesis scheme was developed and new cationic amphiphiles with an asymmetric hydrophobic block were generated.
  • Liposomal dispersions were formed, and their physical and chemical properties and transfection activity were studied.
  • The obtained results indicate good potential of malonic acid amides for creating a new class of cationic amphiphiles used as transfection agents.
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Abstract

Objectives. The aim of this work is to synthesize cationic amphiphiles based on malonic acid amides. The target compounds should contain saturated and unsaturated alkyl chains in the hydrophobic portion, and one or two positive charges in the polar head as created by ethylenediamine and amino acid L-ornithine. For such cationic amphiphiles, we determined physicochemical properties and transfection efficiency of liposomes based on them.

Methods. The initial compound in the synthesis is diethylmalonate. We used C-alkylation to add the first hydrophobic chain (with octylbromide, dodecylbromide, or octadecylbromide). N-oleylamine was used as the second hydrophobic chain, which was attached at the carboxyl group of the malonic acid via amide bond formation. The polar head was represented by ethylenediamine, which was then attached at the second carboxyl group of the malonic acid. Further, L-ornithine was attached to ethylenediamine to produce cationic lipids with two positive charges in the head group. The structures of the compounds were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and elemental analysis. Particle size distribution was evaluated by photon correlation spectroscopy. The luciferase test was used to determine transfection efficiency using HeLa cells.

Results. We have developed a synthesis scheme to produce new cationic amphiphiles with an asymmetric hydrophobic part. The obtained liposomal particles are approximately 120 nm in size and have a relatively high zeta potential of 29–30 mV.

Conclusions. The size of these liposomes allows them to penetrate into cells, which makes it possible to use these compositions for transfection. The high zeta potential shows that the particles are stable. Our results demonstrate that the transfection efficiency of our liposomes (mixed with cholesterol) is comparable to a commercial formulation. Cationic amphiphiles based on malonic acid amides have great potential for liposome development for transfection.

SYNTHESIS AND PROCESSING OF POLYMERS AND POLYMERIC COMPOSITES

The effect of magnetite on the kinetic parameters of sulfur vulcanization of elastomeric materials based on styrene-butadiene rubber (optimal vulcanization time, scorch time, and minimum and maximum torque) was studied. The active filler magnetite exhibits the best properties in the presence of a vulcanizing system containing thiazole-type accelerators.
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Abstract

Objectives. To investigate the possibility of using a cheaper ingredient, such as magnetite, in the synthesis of rubber compounds based on butadiene–styrene rubber by examining its effect on the process of sulfuric vulcanization of butadiene–styrene rubber in the presence of various accelerators.

Methods. The influence of magnetite on the vulcanization kinetics was studied using an Alpha Technologies PRPA 2000 rotorless rheometer. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed using a Mettler Toledo TGA/DSC 2 device to evaluate the effect of magnetite on the butadiene–styrene rubber-based vulcanizates’ oxidation.

Results. Magnetite was found to affect the kinetics of SBR-1500 butadiene–styrene rubber sulfuric vulcanization in the presence of thiazole-type accelerators (2-MBT, 2-MBS); in contrast, magnetite was inactive in the case of diphenylguanidine, sulfenamide T, and tetramethylthiuram disulfide. The obtained TGA/DSC data showed that magnetite has no significant effect on the butadiene–styrene rubber-based vulcanizates’ oxidation and thermal destruction.

Conclusions. The obtained data confirmed magnetite’s capability to act as a butadiene–styrene rubber sulfuric vulcanization activator in the presence of various accelerators. The most significant effect was observed in the presence of thiazole-type accelerators.

CHEMISTRY AND TECHNOLOGY OF INORGANIC MATERIALS

  • Using the V.S. Urusov’s crystal energy theory of isomorphous substitutions, the energies of mixing in the low-temperature modifications of solid solutions (spatial group P21/c) with lutetium oxyorthosilicates (Lu1−xLnx)[(SiO4)0.5O0.5], where Ln represents the rare-earth elements (REEs) of the La–Yb series, were calculated.
  • The dependences of the decomposition temperatures of solid solutions on the REE number and composition were obtained and used to create a diagram of the thermodynamic stability of the solid solutions.
  • It allowed us to predict the substitution limits depending on the temperature or determine the decomposition temperature using the given substitution limits. 
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Abstract

Objectives. This study aimed to predict the limits of substitution and stability of luminescent materials based on low-temperature modifications of solid solutions (spatial group P21/c) with lutetium oxyorthosilicates (Lu1−xLnx)[(SiO4)0.5O0.5], where Ln represents the rare-earth elements (REEs) of the La–Yb series.

Methods. The V.S. Urusov’s crystal energy theory of isomorphous substitutions and a crystallochemical approach in the regular solid solution approximation were used to calculate the energies of the mixing (interaction parameters) of the solid solutions.

Results. Using the V.S. Urusov’s theory, we calculated the energies of mixing (interaction parameters) in the systems under study. The dependences of the decomposition temperatures of solid solutions on the REE number and composition (x) were obtained and used to create a diagram of the thermodynamic stability of the solid solutions, allowing us to predict the substitution limits depending on the temperature or determine the decomposition temperature using the given substitution limits.

Conclusions. The results of the study can be useful when choosing the ratio of components in matrices (host materials) and the amount of the activator (dopant) in the new luminescent, laser, and other materials based on low-temperature modifications of solid solutions of “mixed” REE oxyorthosilicates (Lu1−xLnx)[(SiO4)0.5O0.5].



ISSN 2410-6593 (Print)
ISSN 2686-7575 (Online)