Preview

Fine Chemical Technologies

Advanced search
Vol 15, No 2 (2020)
View or download the full issue PDF (Russian) | PDF

The liquid crystal photoalignment and photopatterning technology is a promising tool for new display and photonics applications. For instance, it can be utilized for rotation of light polarization, voltage-controllable diffraction, fast switching of the liquid crystal refractive index, alignment of liquid crystals in super-thin photonic holes as well as in curved and 3D surfaces.

7-20 214
Abstract

Objectives. Since the end of the 20th century, liquid crystals have taken a leading position as a working material for the display industry. In particular, this is due to the advances in the control of surface orientation in thin layers of liquid crystals, which is necessary for setting the initial orientation of the layer structure in the absence of an electric field. The operation of most liquid crystal displays is based on electro-optical effects, arising from the changes in the initial orientation of the layers when the electric field is turned on, and the relaxation of the orientation structure under the action of surfaces after the electric field is turned off. In this regard, the high quality of surface orientation directly affects the technical characteristics of liquid crystal displays. The traditional technology of rubbing substrates, currently used in the display industry, has several disadvantages associated with the formation of a static charge on the substrates and surface contamination with microparticles. This review discusses an alternative photoalignment technology for liquid crystals on the surface, using materials sensitive to polarization of electromagnetic irradiation. Also, this review describes various applications of photosensitive azo dyes as photo-oriented materials.

Results. The alternative photoalignment technology, which employs materials sensitive to electromagnetic polarization, allows to create the orientation of liquid crystals on the surface without mechanical impact and to control the surface anchoring force of a liquid crystal. This provides the benefits of using the photoalignment technology in the display industry and photonics—where the use of the rubbing technology is extremely difficult. The optical image rewriting mechanism is discussed, using electronic paper with photo-inert and photoaligned surfaces as an example. Further, different ways of using the photoalignment technology in liquid crystal photonics devices that control light beams are described. In particular, we consider switches, controllers and polarization rotators, optical attenuators, switchable diffraction gratings, polarization image analyzers, liquid crystal lenses, and ferroelectric liquid crystal displays with increased operation speed.

Conclusions. The liquid crystal photoalignment and photopatterning technology is a promising tool for new display and photonics applications. It can be used for light polarization rotation; voltage controllable diffraction; fast switching of the liquid crystal refractive index; alignment of liquid crystals in super-thin photonic holes, curved and 3D surfaces; and many more applications.

THEORETICAL BASES OF CHEMICAL TECHNOLOGY

The preparation of the Ni–aluminum (Al)–calcium (Ca) methanation catalyst has been previously comprehensively investigated. The developed catalyst exhibits a low activation temperature and high catalytic activity, thermal stability, and mechanical strength. It is resistant to organic and alkaline carbon dioxide absorbers. The catalyst can be produced in the form of a ring, cylindrical tablets, and extrudates of various geometric sizes.

21-29 101
Abstract

Objectives. This study is devoted to developing new-generation nickel (Ni) catalysts for the purification of a nitrogen–hydrogen mixture from carbon oxides, which should encompass the best qualities of the NIAP-07-series solid catalysts.

Methods. This study used derivatographic and radiographic methods; temperature-programmed recovery, decomposition, and joint temperature-programmed decomposition and recovery; and low-temperature nitrogen adsorption (specific surface determination). The mechanical strength of catalysts was determined using an MP-2C device by crushing granules with an applied load on the end face. The chemical composition and catalytic activity were determined by the methods of TU 2178-003-00209510 Technical Conditions.

Results. Many studies regarding Ni–aluminum (Al)–calcium (Ca) methanation catalyst at all stages of its preparation have been conducted. It is demonstrated that Ni hydrocarboxyaluminate, a precursor of the active component of the catalyst, is formed when Ni hydroxocarbonate is mixed with active alumina in the presence of an aqueous solution of ammonia, and its chemical formula is established. Moreover, it was found that the mechanical strength of the catalyst is determined by the amount of industrial Ca aluminate added to the Ni–Al composition. The compositions of catalysts with different contents of the active component have been optimized.

Conclusions. The developed catalyst has a low activation temperature and high catalytic activity, thermal stability, and mechanical strength and is resistant to organic and alkaline carbon dioxide absorbers. The catalyst can be produced in the form of a ring, cylindrical tablets, and extrudates of various geometric sizes. The methanation unit at Stavrolen (Budennovsk, Stavropol krai, Russia) has begun commercially operating the catalyst. 

In the present study, the concurrent use of quantum chemical methods and correlation analysis for the determination of formation enthalpies of metal-containing organic substances employing alkali metal xanthates as examples was investigated. An excellent correlation was established between the experimental values of enthalpies for the formation of potassium and sodium alkyl xanthates and those calculated utilizing the Austin Model 1 method. The obtained data can be used to calculate the thermal effects of xanthogenation reactions of alcohols as well as to design the production of the corresponding xanthates.

30-37 127
Abstract

Objectives. The aim of this work is to study the possibility of the joint use of quantum chemical methods and correlation analysis to determine the formation enthalpies of metal-containing organic substances using the example of alkali metal xanthates, which are of interest as biologically active substances and effective flotation reagents.

Methods. Semi-empirical methods of quantum chemical calculating (Modified Neglect of Diatomic Overlap, Austin Model 1, Recife model 1 methods) and linear regression analysis were used.

Results. Using the semi-empirical Modified Neglect of Diatomic Overlap, Austin Model 1, and Recife model 1 methods, the enthalpies of formation of 16 potassium and sodium alkyl xanthates were calculated, and the obtained results were compared with experimental data. It was found that the best correlation for potassium and sodium salts of dithiocarbonic acid esters could be observed using the Austin Model 1 method. Using the obtained regression equations, the enthalpies of formation were calculated for 30 xanthates, the organic part of which contained alkyl, cyclic non-aromatic structures, and one or two heteroatoms such as nitrogen, oxygen, and fluorine, and for which there are no experimental data.

Conclusions. As a result of the study, an excellent correlation was established between the experimental and the calculated (by the Austin Model 1 method) values of the enthalpies of formation of potassium and sodium alkyl xanthates. The data obtained can be used to calculate the thermal effect of the xanthogenation reactions of alcohols and to design the production of the corresponding xanthates. 

CHEMISTRY AND TECHNOLOGY OF ORGANIC SUBSTANCES

The specific and volumetric combustion energies, adiabatic combustion temperatures, and conditional final maximum speed of the model rockets with fuels exhibiting various compositions were also calculated for the toluene–MWCNTs and fuel T-1–MWCNTs model systems. The thermodynamic analysis revealed that the addition of MWCNTs could significantly increase the volumetric energy intensity of traditional jet fuels, which could in turn improve the operational characteristics of drones and rockets.

38-46 135
Abstract

Objectives. The addition of high-density carbon materials to jet fuels can lead to a significant increase in the volumetric energy of the fuel combustion. The purpose of the current study was to thermodynamically analyze the possibility of obtaining model hydrocarbon fuels from toluene and T-1 using stacked-cup multiwall carbon nanotubes (MWCNTs).

Methods. Bomb combustion calorimetry was used to define the combustion energy of the MWCNTs in the crystalline state. The temperature dependence of the MWCNTs’ heat capacity in the range 5–370 K and the fusion parameters were estimated using low-temperature adiabatic calorimetry. The physical density of MWCNTs was measured using the pycnometric method. The sedimentation stability of the mixtures of MWCNTs with liquids was determined using centrifugation at 7000 g. The calculations were carried out in MS Excel.

Results. The energy and enthalpy of combustion of a technical sample of MWCNTs in the crystalline state were determined. Based on the smoothed heat capacity values, the standard thermodynamic functions (enthalpy, entropy, and Gibbs reduced energy) of MWCNTs in the crystalline state were obtained in a temperature range of 0–2000 K. The extrapolation of the MWCNTs’ heat capacity was carried out at a temperature of up to 2000 K using the heat capacity of crystalline graphite. It has been established that mixtures of MWCNTs with liquids containing more than 33 mass % of MWCNTs are stable during centrifugal sedimentation at 7000 g. For the toluene–MWCNTs and fuel T-1–MWCNTs model systems, the specific and volumetric combustion energies, the adiabatic combustion temperatures, and the conditional final maximum speed of the model rockets with fuel of various compositions were also calculated.

Conclusions. The thermodynamic analysis showed that the addition of MWCNTs can significantly increase the volumetric energy intensity of traditional jet fuels, which can in turn improve the operational characteristics of drones and rockets. 

The results show that during esterification of malic acid with butyl alcohol exhibiting a normal structure, various byproducts, including esters of fumaric and maleic acids, are formed in the presence of different catalysts. The outcomes also demonstrate that the number of byproducts is independent of the catalyst, with the exception of sulfuric acid. Employing the Amberlyst 36 dry catalyst results in optimal conversion and selectivity for malic acid dibutyl ester.

47-55 133
Abstract

Objectives. The study aims to identify the optimal choice of an effective catalyst for the esterification of malic acid to produce esters of high purity.

Methods. To determine the qualitative and quantitative composition of reaction masses, the following analysis methods were used: mass-spectroscopy (using FinniganTrace DSQ device with NIST 2002, Xcalibur 1.31 Sp 5 database) and gas–liquid chromatography (using the Kristall 2000M software and hardware complex).

Results. Esters of malic acid and butyl alcohol of normal structure were synthesized using the following catalysts: sulfuric, orthophosphoric, p-toluenesulfonic acid, Amberlyst 36 Dry, Amberlyst 36 Wet, KU-2-FPP, and KIF-T. The obtained products were analyzed by gas–liquid chromatography. The structure of the products was confirmed by mass spectrometry. Schemes for the formation of byproducts are proposed. The yields and purity of the malic acid butyl esters obtained using different catalysts were evaluated. The results show that the heterogeneous catalyst Amberlyst 36 Dry is optimal for obtaining a pure malic acid ester with a maximum yield.

Conclusions. The results show that during the esterification of malic acid with butyl alcohol of normal structure, byproducts, such as esters of fumaric and maleic acids, are formed using different catalysts. An accumulation of byproducts occurs as a result of reactions of dehydration of malic acid or its ester. The results also show that the number of byproducts is almost independent of the catalyst, with the exception of sulfuric acid. The Amberlyst 36 Dry catalyst provides an optimal ratio between conversion and selectivity for malic acid dibutyl ester production. 

SYNTHESIS AND PROCESSING OF POLYMERS AND POLYMERIC COMPOSITES

Using the method involving subtraction of IR spectra, it was found that during the manufacture of modified bituminous binders, structural changes occurred in both bitumen and modifiers. A quantitative analysis of the changes in the group composition of the modifiers before and after the modification procedure was performed. The active polymer and structural indices were determined. Notably, a general trend in changing the structural indices for the initial spectra of the rubber powder and hybrid modifier and for the spectra obtained after the procedure of subtracting the spectrum of bitumen binders from the spectrum of bitumen binders was observed. The occurrence of interactions between aromatic molecules in the bituminous component and modifier particles was confirmed.

56-66 127
Abstract

Objectives. This study evaluates the effect of the modification process on the group composition of bitumen and bitumen binders containing rubber powder and hybrid modifier that is based on styrene–butadiene thermoplastic elastomer and rubber crumb. The aim of the study was to determine the presence or absence of functional groups that reflect the direction of physicochemical processes during the preparation of a hybrid modifier in rotary dispersers and during the modification of bitumen binders.

Methods. Rubber powder and hybrid modifier were obtained by high-temperature shear grinding using a rotary disperser. Bitumen and modified bitumen binders were investigated via Fouriertransform infrared spectroscopy. Using the method of spectral subtraction, it was determined that during the process of manufacturing modified bitumen binders, structural changes occur in both bitumen and modifiers. During this study, the extraction of modifiers (rubber powder and hybrid modifier) in toluene was performed.

Results. The quantitative analysis of changes in the group composition of modifiers before and after the modification procedure was carried out. The active polymer and structural indices were determined. The general trend of the change in the active polymer and structural indices was noted for the initial spectra of the rubber powder and hybrid modifier, and their spectra were obtained after the procedure of subtraction from the spectra of bitumen binders.

Conclusions. The interdiffusion of aromatic compounds between the bitumen component and modifier particles was confirmed. On the basis of the results of the extraction of modifiers in toluene, and by taking into account the infrared spectroscopy data, it was determined that during the production of hybrid modifier during the simultaneous grinding of rubber crumb and styrene– butadiene thermoplastic elastomer, there was a chemical interaction between them. 

CHEMISTRY AND TECHNOLOGY OF INORGANIC MATERIALS

Three methods for the synthesis of molybdenum(VI) oxide were developed, and the physicochemical properties of the obtained oxide phases were evaluated. A series of thermal and X-ray diffraction analyses demonstrated that in all cases, the samples were amorphous phases. Heat treatment of the synthesized phases at 580°C led to the formation of a rhombic modification of molybdenum trioxide. The lattice parameters and X-ray density were calculated for all thermolysis products. Moreover, the effect of heat treatment on the particle size of the synthesized samples and their thermolysis products was investigated.

67-76 147
Abstract

Objectives. The present study aims to develop new methods for the synthesis of molybdenum(VI) oxide, which is a precursor for the synthesis of functional materials, as well as to investigate the physicochemical properties of the resulting oxide phases.

Methods. The synthesized phases and the products of their thermolysis were studied by differential thermal analysis, IR spectroscopy, X-ray diffraction analysis, and granulometry.

Results. Three methods for the synthesis of molybdenum(VI) oxide were developed, and the physicochemical properties of the oxide phases obtained were studied. The first method consisted in the reaction of molybdenum pentachloride with a 6.0–9.5 mol/L ammonia solution, the second one was the reaction of niobium pentachloride with a sulfuric acid solution, and the third method involved the reaction of ammonium molybdate with nitric acid, affording brown molybdenum(V) MoO(OH)3 hydroxide, a bright blue precipitate of molybdenum blue MoO2.75, and white hydrated oxide MoO3·H2O, respectively.

Conclusions. A series of thermal and X-ray diffraction analysis demonstrated that in all cases the samples were amorphous phases. Heat treatment at 580 °C of the synthesized phases led to the formation of a rhombic modification of molybdenum trioxide. The lattice parameters and X-ray density were calculated for all thermolysis products. The effect of heat treatment on the particle size of the synthesized samples and their thermolysis products was studied. Particle size analysis demonstrated that particles of different diameters were formed depending on the synthetic method. The smallest particle size (0.3–0.6 µm) was found in molybdenum trioxide, a product of the thermolysis of the sample obtained by the reaction of molybdenum pentachloride with a concentrated ammonium solution. 

ANALYTICAL METHODS IN CHEMISTRY AND CHEMICAL TECHNOLOGY

A method for determining the specific activity of the humanized recombinant monoclonal antibody eculizumab was designed and validated. A comparative evaluation of the specific activity of Soliris® (Alexion Pharmaceuticals Inc., USA) as well as biosimilar PRK-001 (Pharmapark, Russia) was performed using the developed method. The similarity between PRK-001 and Soliris® in relation to their specific activity, i.e., binding to the human complement system C5 protein, was confirmed.

77-85 122
Abstract

Objectives. Developing reliable and accurate analytical methods is necessary for comparative pharmaceutical analysis using physicochemical, biological (in vitro), preclinical, and clinical trials. The main objective of this study was to develop and validate an in vitro method for determining the specific activity of the recombinant monoclonal antibody eculizumab.

Methods. The method of indirect enzyme immunoassay was used in the study.

Results. A method for determining the specific activity of the humanized recombinant monoclonal antibody eculizumab was described and validated for the first time. A comparative evaluation of the specific activity of Soliris® (Alexion Pharmaceuticals Inc., USA), and its biosimilar PRK-001 (Pharmapark, Russia) was performed using the developed method.

Conclusions. The similarity of PRK-001 and the original Soliris® in relation to their specific activity, that is, binding to the human complement system C5 protein, was proved. 



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