Fine Chemical Technologies (E-Journal) / Тонкие химические технологии
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ИНТЕНСИФИКАЦИЯ ПРОЦЕССА ЖИДКОФАЗНОГО ОКИСЛЕНИЯ ЦИКЛОГЕКСАНА
Get PDFLiquid-phase oxidation of cyclohexane to cyclohexanol and cyclohexanone was studied in the absence of solvents under an air pressure of 0.5-5 MPa, in the temperature range 115-150 °C, catalyzed by N-hydroxyphthalimide (N-HPI). It was established for the first time that the use of N-HPI as a catalyst in place of the conventionally used metal salts of variable valence allowed a 2-3-fold increase in the conversion of the initial hydrocarbon and selectivity from 70-75 to 90%. The combined use of N-HPI with cobalt(II) acetate results in an additional increase in the conversion of cyclohexane by 30-40%, the selectivity of cyclohexanol and cyclohexanone formation to 94-97%, which seems to be due to the synergistic effect between the two components of the catalyst. The mechanism of catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone is discussed. It has been suggested that N-HPI plays a dual role in the oxidation of cyclohexane: it catalyzes the conversion of cyclohexane to cyclohexanol and cyclohexanone and, on the other hand, promotes the conversion of cyclohexanol to cyclohexanone, thereby substantially reducing the formation of adipic acid and its esters, by-products of the reaction, and increases selectivity of oxidation. This also explains the unusually high (1.3-1.5 : 1) ketone: alcohol ratio in the oxidation products of cyclohexane in the presence of N-HPI. The high selectivity of the formation of the desired products, the conversion of cyclohexane, the moderate temperature, the available catalyst, suggest that this method of oxidizing cyclohexane to cyclohexanol and cyclohexanone may be of interest for further practical use
АНАЛИЗ ИНСЕКТИЦИДНЫХ ГЕЛЕЙ, СОДЕРЖАЩИХ ФИПРОНИЛ, МЕТОДОМ ОБРАЩЕННО-ФАЗОВОЙ ВЭЖХ
Get PDFThe article considers fipronil determination by the method of RP HPLC in isocratic mode with ultraviolet detection at 280 nm. The analysis of insecticidal gels containing fipronil and fipronil mixture with chlorpyriphos was carried out. The possibility and expediency of determining the isomeric composition of fipronil were considered. The conditions for carrying out extraction of insecticides from gel matrices containing food attractive, including additional processing by ultrasound, were determined. The developed mode of extraction of active ingredients (fipronil and chlorpyriphos) is based on the preferred homogenization of the gel sample with a minimum amount of water followed by extraction with isopropanol acidified with acetic acid. The proposed scheme differs from the previously realized chloroform extraction by the stage of sample preparation. However, under these conditions in case of the gel matrix it is possible to achieve a high degree of homogeneity of the sample and to prevent possible hydrolysis of the target components. At the same time, the selected conditions are well combined with the polarity of the mobile phase upon direct separation. Selected chromatography modes allow identifying the title compound in real insecticides without overlapping signals from other extractable components using the trivial stationary phases. The possibility and expediency of carrying out chromatographic analysis to determine the optical isomers of the title compounds with different insecticidal activity have been considered. The optimal concentration range of fipronil determination in the working solution is from 0.005 to 0.15 mg/ml (chlorpyriphos, from 0.002 to 0.15 mg/ml). The limit of determination of substance in the working solution/swabs is 0.0005 mg/ml
КОМПОЗИЦИОННЫЙ МОДИФИКАТОР АСФАЛЬТОБЕТОНОВ, ПОЛУЧАЕМЫЙ МЕТОДОМ ВЫСОКОТЕМПЕРАТУРНОГО СДВИГОВОГО СОИЗМЕЛЬЧЕНИЯ ШИННОЙ РЕЗИНЫ И СБС-ТЕРМОЭЛАСТОПЛАСТА
Get PDFРАЗРАБОТКА РЕАКЦИОННО-РЕКТИФИКАЦИОННОГО ПРОЦЕССА ПОЛУЧЕНИЯ ОКИСИ МЕЗИТИЛА. I. МОДЕЛИРОВАНИЕ КИНЕТИКИ И ФАЗОВЫХ РАВНОВЕСИЙ В РЕАКЦИОННОЙ СИСТЕМЕ
Get PDFMesityl oxide is an important product of organic synthesis, which is used in the manufacture of pharmaceuticals and as a solvent. The demand for mesityl oxide is growing, which determines the need for further improvement of its production. The disadvantages of the traditional methods of obtaining mesityl oxide are low values of reagent conversion and selectivity. To eliminate them, it is proposed to obtain mesityl oxide in a combined reaction-rectification process. The combination of chemical transformation and separation of the resulting reaction mixture by means of rectification in one apparatus allows for a continuous withdrawal of the formed products from the reaction zone, which increases the rate of the target reaction, conversion and selectivity. In accordance with the modern strategy for the development of chemical-technological processes, the collection and processing of physical and chemical information on the properties of the components and mixtures contained in the reaction system was performed. Based on the experimental data, the parameters of the phase equilibrium model are determined, and its adequacy is estimated. The phase equilibrium model was used to construct a distillation diagram, to verify its consistency, and to conduct computational studies of the reaction-rectification process. The thermochemical parameters of the target reactions are calculated, the equilibrium constants are determined, and their temperature dependence is established. On the basis of the analysis of the literature data, a kinetic model of the process is proposed, and the conditions favorable for the course of the desired chemical transformation are determined with the use of this model. The obtained data are necessary for carrying out the analysis of the statics, constructing the basic technological scheme and calculating its static parameters
ГИДРОТЕРМАЛЬНО-МИКРОВОЛНОВОЙ СИНТЕЗ НАНОКРИСТАЛЛИЧЕСКОГО MnO2 В ПРИСУТСТВИИ ГЕКСАМЕТИЛЕНТЕТРАМИНА
Get PDFThe article considers a non-conventional approach to the synthesis of various polymorphic modifications of manganese dioxide. The approach consists in hydrothermal microwave processing of a reaction mixture containing potassium permanganate and hexamethylenetetramine. We emphasize the relevance of the work due to such MnO2 properties as catalytic and photocatalytic activity, its application in accumulators, supercondensers and biochemistry. We report on the first detailed study on the role of temperature, synthesis duration and pH value on the phase composition and morphology of nanocrystalline MnO2. We show that the phase composition of manganese dioxide is largely determined not only by temperature, synthesis duration and pH value, but also by the acid added to the reaction mixture (nitric or sulphuric). In particular, the presence of sulfuric acid apparently results in α-MnO2 stabilization. It is noted that the type of the acid used in the course of the synthesis, as well as other synthesis conditions exercise no significant influence neither on the shape nor on the size of α-, γ- and δ-MnO2 particles. In contrast, the morphology of β-MnO2 turned out to be extremely sensitive to the synthesis conditions. Long (24 h) hydrothermal processing of reaction mixtures at рН 0.5-1 results in the formation of single-phase pyrolusite. The microstructure of the latter is determined by the reaction mixture composition
СОЕДИНЕНИЯ ВИСМУТА И ЕГО КОМПЛЕКСЫ С ПОРФИРИНАМИ: ПРИМЕНЕНИЕ, СТРУКТУРА И СВОЙСТВА
Get PDFBismuth and its compounds have been known since ancient times and now are widely used in practice in various fields. Bismuth use in medicine can be traced back to the Middle Ages, and its wide application is due to its very low toxicity - for most bismuth compounds it is less than for sodium chloride. Bismuth and its compounds, in particular salts, are used in medical practice in the treatment of diseases such as spirochetosis, gastric and duodenal ulcer, leishmaniasis and coronaviral infection, as well as in cancer therapy. In addition to solid preparations liquid peroral pharmaceutical forms have been developed for the treatment of diarrhea, colitis, ulcers etc. Bismuth preparations are used in stomatology for the treatment of inflammatory diseases of paradontium. The review considers the syntheses and properties of bismuth complexes with natural and synthetic porphyrins, which are used in medicine and other fields of science and technology. Considerable attention is paid to the structure features of bismuth porphyrins complexes, their dimeric structures, and the influence of various extra ligands. The counterion nature and structure make a substantial contribution in solving the problem of complexes stability. The central bismuth atom in these complexes extends far above the plane of the macrocycle due to the large ionic radius. Thus, the counterions action on the conformation, physicochemical properties and stability of metal porphyrins complexes is shown. A separate section is devoted to unique and interesting properties of bismuth porphyrins complexes, such as fluorescence and color variation of crystals.Обзор посвящен использованию висмута и его соединений, в частности солей, в медицинской практике при лечении таких заболеваний, как спирохетозы, язвенная болезнь желудка и двенадцатиперстной кишки, а также в терапии рака. Наряду с твердыми препаратами разработаны жидкие пероральные лекарственные формы для лечения диареи, колитов, язв и др. Препараты висмута используются в стоматологии для лечения воспалительных заболеваний пародонта. Рассмотрены синтезы и свойства висмутовых комплексов с природными и синтетическими порфиринами, которые находят применение в медицине и иных областях науки и техники. Значительное внимание уделено особенностям строения висмутовых комплексов порфиринов, их пространственной структуре, влиянию стерических и электронодонорных эффектов, образованию димеров и влиянию различных экстралигандов. Так, показано действие противоионов на конформацию, физико-химические свойства и устойчивость висмутовых металлокомплексов порфирино
100 лет Второму МГУ
Get PDFThe solemn meeting to mark the 100th anniversary of the founding of the Second Moscow State University was held on October 16, 2018.16 октября 2018 года состоялось торжественное собрание, приуроченное к празднованию 100 лет со дня основания Второго Московского государственного университета
ВЫБОР ЭКСТРАКТИВНЫХ АГЕНТОВ ДЛЯ РАЗДЕЛЕНИЯ СМЕСИ ХЛОРОФОРМ - МЕТАНОЛ -ТЕТРАГИДРОФУРАН
Get PDFVariants of the extractive distillation of chloroform - methanol - tetrahydrofuran equimolar mixture with industrial separating agents are considered. The basic system shows opposite deviations from the ideal behavior, because it contains binary azeotropes with minimum and maximum boiling points (3.3.1-4 system according to Serafimov’s classification). The choice of selective substances for extractive distillation was carried out taking into account the concentration dependences of the excess molar Gibbs energy of the binary constituents of the derivative system “chloroform - methanol - tetrahydrofuran - industrial test agent (ethylene glycol (EG), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (N-MP))” at 101.32 kPa. Based on the results of the evaluation of the thermodynamic criterion, DMSO and N-MP are recommended. Both agents show selective effect when separating two binary constituents. EG is selective only with respect to chloroform-tetrahydrofuran mixture. Since the tested agents show different selective effects, the final agent choice determines the qualitative composition of the product flows in the column for the extractive distillation of the three-component mixture (the first column of the flowsheet) and, accordingly, the structure of the total flowsheet. The schemes consist of two two-column complexes for extractive distillation (for the basic three-component mixture and for the binary mixture). The maximum contribution to the total reboiler energy consumption of the distillation columns is made by the first extractive distillation column: 65% (EG), 53% (N-MP) and 24% (DMSO). The use of the most selective agent reduces the energy consumption of this column: the reboiler load is maximal in the case of EG, in comparison with which the load is 47% lower in the case of N-MP and 76% lower in the case of DMSO
МАЛООТХОДНАЯ ТЕХНОЛОГИЯ ПОЛУЧЕНИЯ ГЛИЦИДОЛА ПЕРОКСИДНЫМ МЕТОДОМ
Get PDFA technological process of manufacturing glycidol designed for the production capacity of 10 thousand tons per year and consisting in the direct oxidation of allyl alcohol with an aqueous solution of hydrogen peroxide in the presence of nanostructured titanium silicate in methanol is proposed. Due to the exothermic process, the solvent is not only a homogenizer of the mixture of the initial reagents of the epoxy process - allyl alcohol and hydrogen peroxide ensuring their interaction on the surface of the solid catalyst: it also prevents overheating of the reaction mass. On the basis of the research trial of the process the optimal parameters of the process were determined: temperature 30-40 °C; pressure 0.25 MPa; the initial hydrogen peroxide : allyl alcohol ratio = 1:(3-4) mass., methanol concentration in the reaction mixture 12-13 mol/l. Hydrogen peroxide conversion is 98%, the yield of the glycidol - 94%, the selectivity is no less than 95%. The process includes three main stages: (1) raw materials preparation, (2) liquid-phase epoxidation of allyl alcohol, (3) distillation of the target product. The scheme involves recirculation of unreacted allyl alcohol and the solvent - methanol. The developed technological process provides the following indicators (per 1 t of commercial glycidol): consumption of allyl alcohol no more than 0.843 t; consumption of hydrogen peroxide no more than 0.50 t (calculated for 100% hydrogen peroxide); consumption of methanol is no more than 0.022 tons All the waste products correspond to the 3-rd or 4-th hazard class
ПЕРСПЕКТИВЫ ПРИМЕНЕНИЯ ТЕПЛОВЫХ НАСОСОВ ПРИ ПРОВЕДЕНИИ КОМБИНИРОВАННЫХ МАССООБМЕННЫХ ПРОЦЕССОВ
Get PDFThe prospects of using heat pumps for the separation of mixtures by combination of different mass transfer processes are considered, which is associated with the supply and removal of thermal energy. The heat released in some stages can be successfully used at other stages of separation. Using heat pumps makes it possible to change the temperature potentials of heat fluxes, which greatly improves the efficiency of regenerative heat transfer. If a vapor phase forms when carrying out mass transfer processes, it can be used as the working fluid of the heat pump of the open type. If mass transfer processes are carried out without the formation of vapor phases, it is necessary to apply heat pumps of the closed type, in the circuit of which a variety of intermediate heat transfer fluids circulate. The article briefly describes the features of mixtures separation by a combination of fractional crystallization by evaporation, dissolution, fractional melting, distillation and rectification with the use of compressor heat pumps of open and closed type. In order to assess the energy efficiency of different variants of combined processes and to compare them with traditional separation it is suggested to use the relative equivalent consumption, which makes it possible to take into account the different cost of thermal and electric energy required for carrying out the considered process of separation. Different variants of organizing the combined separation are compared. It was found that their energy efficiency significantly depends on the composition of the initial mixture, on requirements for the separation products, as well as on the position of the eutectic point on the liquid - solid phase charts. It was shown that the use of heat pumps allows reducing several times energy costs, as well as the consumption of refrigerants for combined separation