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Fine Chemical Technologies

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Vol 8, No 5 (2013)
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THEORETICAL BASES OF CHEMICAL TECHNOLOGY

3-19 89
Abstract
The basic approaches are considered to the creation of energy efficient flowsheets for extractive distillation (ED). A brief analysis of works dedicated to the choice of effective entrainer, of optimal ED flowsheets parameters and the use of certain special methods to reduce ED power consumption (heat exchange between the condensing and evaporating streams of various distillation columns, combination of the principle of heat pump and heat and cold supply stepped by the height of column). The focus is the development of energy-saving technologies on the base of the optimal structure of the schema partition identification. The classic ED flowsheets and ED flowsheets with partly coupled thermally and material flows (PTCDS). Algorithms are described for synthesis of flowsheets manifold based on the graph theory. ED flowsheets with PTCDS to separate mixtures of a number of industrial products are demonstrated such as C4 fraction of dehydrogenation ED with acetonitrile, aromatic separation from the reforming and vapor cracking factions with N-formylmorpholine, ethanol-water mixture with ethylene glycol. Analysis of the literature and the author's research showed that the energy efficiency of the PTCDS extractive distillation of various mixtures is quite different: energy consumption reducing in PTCDS can be small (~ 1.5%), such as ED mixtures of ethyl acetate-ethanol with dimethylsulfoxide, and may increases up to 20-30%, as at ED of the mixture acetone-chloroform with N,N-dimethylformamide. At the paper you will find original author's hypothesis about the causes of various energy efficiency of the PTCDS for various mixes separation by ED.
20-39 49
Abstract
The motion of the charged particles in graphen in the frame of the quantum non-local hydrodynamic description is considered. It is shown as results of the mathematical modeling that the mentioned motion is realizing in the soliton forms. The dependence of the size and structure of solitons on the different physical parameters is investigated.
40-43 71
Abstract
Now the world has a certain interest in methods for producing hydrocarbon fuels from fats. The most modern and advanced way of these reactions is the deoxygenation (decarbonylation / decarboxylation) acids. As catalysts for these reactions palladium nanoparticles are used. Now attempts are being made to replace it with a cheaper metal – copper or nickel. The mechanism of these reactions are currently poorly understood. Great help in resolving this issue may have a quantum-chemical methods. This paper describes the energy characteristics of the various structures that may be implemented in the adsorption molecule fatty acid on copper and palladium clusters.
44-48 70
Abstract
The syn-anti isomerization of bis-(η3 -allyl)nickel complexes (allyl – C3H5, 2-CH3C3H4, 1-CH3C3H4) has been studied using the density functional theory (DFT-PBE). Calculations indicated that in all cases isomerization goes through 3 steps according to η3 -η1 -η3 -mechanism. The rate-limiting step of that is vinyl fragment rotation in η1 -allyl ligand.
49-54 50
Abstract
Several ab initio (DFT-B3PW91/6-31g(d,p)) calculations of cage-like siloxanes (MeSiO1.5)n (n = 4-12) have been made. It was shown that cubane-like structure (MeSiO1.5)8 is the most stable one. Refined mechanism of polymeric metallasiloxanes cleavage by the silanolates has been suggested. It has been shown that isomerisation of Cu-containing siloxanes (rearrangement of sandwich-like form into globule-like form) is mostly governed by the coordination properties of solvates.
55-61 49
Abstract
The initial stages of methylphenyldimethoxysilane hydrolysis in acetone were investigated. The boundaries of diffusion and kinetic areas of the process were defined. Methylphenyldimethoxysilane hydrolysis proceeds to kinetic mode at a lower mixing intensity than methylphenyldichlorosilane hydrolysis does. The constant of methylphenyldimethoxysilane hydrolysis rate (Kh = 0.5×10<sup>-3</sup> s<sup>-1</sup> ) was found. Unlike methylphenyldichlorosilane hydrolysis, methylphenyldimethoхysilane hydrolysis products composition is independent of the concentration of acetone. This fact indicates a low selectivity of the process. The part of oligomeric products is quite large. Homocondensation is supposed to make a greater contribution to the formation of methylphenyloligoorganosiloxanes than heterocondensation does. The presence of methylphenyldimethoxysilane hydrolysis products depending on water-methylphenyldimethoxysilane ratio shows that the hydrolysis occurs in both phases of the system, and the main reaction zone is the organic phase.
62-71 121
Abstract
The industrial separation of binary azeotropic mixtures and mixtures with relative volatilities of substances close to 1 uses special rectification techniques with an addition of a third component. These methods are classified by the main characteristics: by the volatility of the additive in the case of extractive and re-extractive rectification, and also by the change in the number of liquid phases of the system after the introduction of a new component in the case of heteroazeotropic rectification. The main problems in the field of extractive distillation, the most popular industrial method of separating azeotropic mixtures that require further theoretical study are formulated. The review includes primarily theoretical studies performed in different years at the department of chemistry and technology of basic organic synthesis of Lomonosov Moscow State University of Fine Chemical Technologies and is dedicated to special methods of distillation of binary azeotropic mixtures

CHEMISTRY AND TECHNOLOGY OF MEDICINAL COMPOUNDS AND BIOLOGICALLY ACTIVE SUBSTANCES

72-76 52
Abstract
Liposomal levofloxacin was prepared with the extrusion technique. Levofloxacin is a fluoroquinolone used for resistant tuberculosis treatment. Traditional lipids such as phosphatidylcholine (PC), as well as a mixture of PC and cholesterol (Chol) were used for liposome preparation. Antibiotic encapsulation into the liposomes was carried out with the passive and active loading methods. The active method of levofloxacin loading into liposomes was conducted with ammonium sulphate gradient. Levofloxacin encapsulation efficiency into liposomes containing PC/Chol (4:1, w/w) was found to be as high as 90% when active the loading method was used, while levofloxacin encapsulation efficiency was as low as 20% when the passive loading method was used. Levofloxacin releasing kinetics with Franz diffusion cell was investigated. Levofloxacin was shown to release gradually from liposomes containing PC and Chol to 18% for 21 h, while levofloxacin released completely for 3 h from antibiotic solution. The prepared liposomal levofloxacin was used to test its activity on extensively drug resistant strain Mycobacterium tuberculosis СN-37 growth with automatized system BACTEC MGIT 960. Mycobacterium tuberculosis СN-37 was resistant to rifampicin, isoniaside, streptomicin, ethambutol, pyrazinamide, ofloxacin, amikacin, capreomicin. Mycobacteria growth monitoring with automatized system BACTEC MGIT 960 was based on fluorescence measurement of fluorophore located at the bottom of Mycobacteria Growth Indicator Tube (MGIT). This fluorophore is «neutralized» by high oxygen concentrations. The living bacterial cells take in oxygen, which results in fluorescent increase. The liposomal levofloxacin as well as levofloxacin solution at 1 and 2 mkg/mL were found to delay mycobacteria growth by 1-2 days while both levofloxacin forms at 4 mkg/mL inhibited mycobacteria growth completely. It means that the liposomal levofloxacin is active as an antibiotic solution against mycobacteria. Summing up, it is the active loading method that can be rationally used for the liposomal levofloxacin preparing with maximal encapsulation efficiency. The prepared liposomes loaded with levofloxacin allow the antibiotic to release gradually. So, the antibiotic is active for a long time. It is important for increase of the antibiotic activity within human organism.
77-82 50
Abstract
A high-tech technology for highly sensitive test systems is proposed based on conjugates "polymer microsphere-bioligand" for express diagnosis of autoantibodies to the modified protein (proteopathy) for example, thyroglobulin, using the method of latex agglutination reaction (in vitro).

CHEMISTRY AND TECHNOLOGY OF INORGANIC MATERIALS

83-88 56
Abstract
New acetamide complexes of erbium and lutetium bromides LnBr<sub>3</sub>4AA4H<sub>2</sub>O, (Ln = Er, Lu; AA  acetamide) were synthesized. The resulting complexes were characterized by chemical analysis, infrared spectroscopy and X-ray diffraction method. It is shown that the coordination of the ligands (water molecules and acetamide) by the lanthanide atoms occurs through the oxygen atoms, and the coordination polyhedron is a distorted square antiprism (CN = 8). The bromide ions are not coordinated and are located in the outer sphere. The degree of ionic character of the lanthanide–acetamide bonds was estimated. The structural characteristics of the complexes [LnL<sub>4</sub>(H<sub>2</sub>O)<sub>4</sub>] Br<sub>3</sub> (Ln = Er, Lu; L = AA) were compared.
89-93 46
Abstract
Dissipation in selenium was investigated using internal friction spectrum for the temperature range -150–250°C and the frequency domain 0.1–10 Hz. It was found that only the use of a combined specimen with isinglass stone undercoat allows the tests of selenium in the mentioned temperature range. For unannealed selenium four local dissipation peaks of the internal friction spectrum were observed in the temperature range -130÷+225°C. Two peaks (α and ) are relaxation peaks, and two others ( c  and С) are nonrelaxation peaks. All observed dissipation peaks of the internal friction spectrum were interpreted on the basis of calorimetric tests results. It was also found that the thermal treatment of selenium results in the annihilation of the α-relaxation peak and strong decrease of the dissipative process С.
94-98 63
Abstract
Methods of chem-mech polishing and chemical etching were described, and characteristics of Ge wafers were investigated corresponding to technical requirements of MBE growth. Investigation methods included optical microscopy, X-ray diffraction analysis, high-resolution diffraction analysis, AFM and IR-Fourier microscopy.

MATHEMATICAL METHODS AND INFORMATION SYSTEMS IN CHEMICAL TECHNOLOGY

99-104 53
Abstract
In adiabatic approach the assessment of rate of direct and synchronous transitions of nuclear kernels between various provisions of balance is made at low temperatures. Conditions of efficiency of concert transitions in comparison with direct transitions are received.
105-117 42
Abstract
The article describes the mechanism of the elastic interaction of local micro-defects called holes, which are formed and accumulate in the forced elasticity area in front of the fracture crack in polymers. Amorphous glassy polymers such as PMMA are considered. The elastic field of the holes, their own elastic energy, the interaction energy of the holes and the strength of their two-body interaction are calculated. The interaction of holes leads to the fact that each hole is surrounded by an "atmosphere" of smaller holes. It is shown that the fracture crack is the source of its own elastic field. It is shown that the holes diffuse toward the front of the crack. The diffusive flux of the holes was calculated.
118-121 121
Abstract
Boundary value problem of transient heat conduction for unlimited bar with given heat exchange at one of its boundaries is considered. The problem is solved with the method of integral transformations. Analytical solution is obtained; graphs characterising the process for different media are constructed.
122-127 52
Abstract
The article presents comparative analysis of the non-steady heat transfer problem solutions in the area of the border moving according to the law  t under the conditions of temperature heating. The solutions were obtained using the method of difference schemes and analytically.
128-135 50
Abstract
Searching the quantitative structure–property relationships (QSPR) is one of the most important tasks of the contemporary theoretical chemistry. The models obtained may be used for prognosis of the chemical substances properties on the basis of their structure and for searching compounds with predetermined properties. About 980,000 structure–property linear models have been constructed for parameter lgKa (Ka – acidity constant) of a number of organic compounds. Different training and test sets obtained by means of multiple random halving the initial set of compounds have been used to desigh these models. Molecular descriptors have been selected from some set of topological molecular parameters reflecting different particularities of molecular structures. The Wiener index, the generalized weighted connectivity index, the number of hydrogen atoms, some spectral characteristics of graph, representing molecule, etc. are among these parameters. About 90 the best models have been selected on the basis of some quantitative criterium, characterizing the model precision both on training and test sets. These models have been used for evaluation of lgKa for other compounds not included into the initial set of compounds, by calculation of lgKa for every model and averaging the results obtained. Besides, the structural particularities possessing the most significant influence on the given property have been derived on the basis of analysis of these models. The computer program Wolfram Mathematica 8 has been used in this work.
136-140 65
Abstract
On the basis of functional modeling methodology a complex of models in IDEF0 notation was created. It describes the production technology and quality control procedure for methyl tertiary butyl ether manufacturing.


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