Key words: глицирризинат аммония, глицирам, глицирризиновая кислота, глицирретиновая кислота, моногликозид глицирретиновой кислоты, массспектрометрия с ионизацией электрораспылением, ВЭЖХ-МС, субкритическая вода
A method for synthesis of glycyrrhetinic acid monoglycoside by hydrolysis of
glycyrrhizic acid in subcritical water at temperatures between 100 and 300 °C is
developed. The maximum yield of the target product is obtained at 160 °C.
Key words: полимерный нанокомпозит, сверхкритический диоксид углерода, квантовые точки, фотолюминесценция, политетрафторэтилен, полиэтилен низкой плотности, диффузионное внедрение
Luminescence of composites based on quantum dots CdSe embedded into low-density
polyethylene (LDPE) and polytetrafluoroethylene (PTFE) powders using supercritical
carbon dioxide is studied. It is shown that thermal treatment of the resulting powders
in air in the case of LDPE causes the CdSe photoluminescence band shift to shorter
wavelengths, but in the case of PTFE — to longer wavelengths with simultaneous
decrease of integral luminescence intensity. The behavior of photoluminescence bands
under near UV radiation in both cases is determined by photo-oxidation processes
on the CdSe nuclei.
Key words: статистическая физика, критические явления, теория молекулярных спектров
Careful analysis of CARS-spectroscopy data for carbon dioxide Fermi-dyad shows
that critical density variance must not exceed 0.4 and the lifetime of critical density
fluctuations is not less than 10 ns. To comprehend the experimental data, the contribution
of critical fluctuations to the spectral line width is evaluated taking into consideration
their lifetime.
Key words: температура, давление, плотность, концентрация, фаза, флюид, уравнение состояния, фактор сжимаемости, приведенные параметры
The results of thermal and thermodynamic properties (diagrams of state) calculation
of water-aliphatic alcohol (methanol, ethanol, n-propanol) systems in liquid and vapor
phases, as well as in the state of supercritical fluid are presented. They are based on the
equation of state that represents the compressibility factor as power series of reduced
density (ω = ρ/ρcr) and temperature(t = T/Tcr)
\(Z=\frac{\rho}{RT\rho_m}=1+\sum_{i=1}^{m}\sum_{j=0}^{n_i}\frac{a_{ij}\omega^i}{\tau^j}\)
and describes the experimental р, ρ, Т, х-relations with an
average relative error 1.2%.
Key words: этанол, топливо, гидролиз, газификация, сахарообразование, сверхкритические флюиды
Publications devoted to the application of supercritical fluids to deep biorefinery of
vegetable raw materials for production of wide range of products, such as ethanol,
liquid and gaseous fuels, sugars, organic acids, and oils are reviewed and analyzed. The
specific features of the supercritical fluid technologies and their advantages in
comparison with the existing traditional methods of biorefinery of vegetable raw
materials are demonstrated.
Key words: сверхвысокомолекулярный полиэтилен, субкритическая вода, пористость, имплантат
The method of subcritical water extraction of NaCl from ultrahigh density polyethylene
(UHDPE) samples is developed as a stage in the manufacturing of porous polymer —
a promising material for implant production. Optimal process parameters were
determined as follows: pressure 250 atm, temperature 120 °С, water flow rate 3 g/min.
This method provides with a tenfold reduction of salt extraction time (from 10 to 1 h).
The main pore diameter of UHDPE determined by scanning electronic microscopy
ranges from 80 to 700 µm.
Key words: фазовые диаграммы, растворимость, расслаивание растворов, критические явления
The system LiOH—H<sub>2</sub>O is characterized by the immiscibility phenomena both in
equilibrium with vapor and solid saturated solutions or without solid phase. Solubility
of LiOH increases as a result of immiscibility phenomena at ∼355 °С and further increases
above this temperature up to the melting point. The immiscibility region (g - l<sub>1</sub> - l<sub>2</sub>)
is terminated by the critical phenomena (g = l<sub>1</sub> - l<sub>2</sub>) at ∼390 °С. A separation of liquid
phases is observed at elevated pressures (at ∼39 MPa) and temperatures up to 425 °C.
Key words: пропан-бутановая смесь, сверхкритическое флюидное состояние, деасфальтизат, растворимость, карбонатный щебень, импрегнация
A comprehensive process for deasphaltizing of heavy oil residue and subsequent
treatment (impregnation using a solvent in supercritical fluid state) of a carbonate
macadam by bituminous compounds (deasphaltizate) is developed. The purpose is to
improve its functionality of the material and, above all, to reduce its water absorption
capacity. The process parameters are specified based on the newly obtained data on
thermal capacity of heavy oil residue and deasphaltizate. The results of the process
experimental realization and characteristics of impregnated macadam, including the
water absorption capacity decreased from 3.6 to 0.54 %, are presented.
Key words: сверхкритическая флюидная хроматография, СФХ, природные ароматические кислоты
Derivatives of benzoic and cinnamic acids are secondary metabolites of plants, widely
spread in nature and possessing biological activity. It is shown that supercritical fluid
chromatography (SFC) provides a high performance separation of nine most important
representatives of this class of compounds with selectivity, which is dramatically different
from the reversed-phase high-performance liquid chromatography. The retention and
separation parameters of analytes for four chromatographic stationary phases of different
nature are compared and the effect of supercritical fluid parameters and the composition
of the mobile phase onto the chromatographic separation are analyzed. The optimum
separation can be achieved using a silica-based sorbent with 2-ethylpyridinium linked
groups. The proposed approach to determine the above mentioned compounds is based
on the combination of chromatographic separation with multiwavelength
spectrophotometric detection. It provides the detection limits in the range of 13.0—51.3
mg/L and the duration of analysis about 2.5 min. The developed approach is successfully
tested on the analysis of real objects — three different kinds of wine.
Key words: субкритическая вода, аралозиды, аралия маньчжурская, сапонины, cапарал, олеаноловая кислота, ВЭЖХ-МС
A method to obtain oleanolic acid (OA) and its derivatives by hydrolysis of aralia
manchurian in subcritical water is developed. It is carried out on an example of
pharmaceutical preparation «Saparal» at 120—240 °C in static regime. A maximal yield
of OA is obtained at 210 °C.
Key words: сверхкритическая флюидная экстракция, микроволновое излучение, редкоземельные элементы, торий, уран, диоксид углерода, монацитовый концентрат, фосфогипс, трибутилфосфат, ди-(2-этилгексил)фосфорная кислота
Supercritical fluid extraction (SCFE) using carbon dioxide containing tributyl phosphate
(TBP) and di-(2-ethylhexyl)phosphoric acid (D2EHPA) or their adducts with HNO<sub>3</sub>
is proposed as a method to extract rare earth elements (REE), Th and U from monazite
concentrate (MC) and phosphogypsum (PG). On the first stage, the product of baking
the MC with Na<sub>2</sub>CO<sub>3</sub> (MCS) is obtained in the presence of coal under microwave
irradiation, in which phosphates of REE, Th and U present in the MC are converted
into their oxides. Up to 50 % of REE can be recovered from the powdered MCS by
the adducts of TBP and D2EHPA with HNO<sub>3</sub> in SCFE conditions, whereas Th and U
remain in the solid phase. After a complete dissolution of the MCS residue in the
mixture of 4 M HCl and 0.05 M HF, Th and U are quantitatively extracted using
supercritical carbon dioxide containing D2EHPA and thus separated from the REE
that remain in an acidic solution. The conditions of quantitative isolation of REE, Th
and U from PG are determined and the schemes for complex processing of MC and
PG targeted to the recovery of REE separated from Th and U are suggested.
Key words: сверхкритический диоксид углерода, СКФ-микронизация, сверхкритическое антисольвентное осаждение, арбидол, биодоступность
The possibility to obtain microparticles of arbidol using supercritical antisolvent (SAS)
precipitation method is demonstrated. Non-monotonic dependence of average particle
size on arbidol concentration in methanol and DMSO is observed. The position of its
minimum depends on the type of used solvent. SAS technique allows one to vary the
size (1.8—500 μm) and morphology of arbidol particles which can be operated by
process parameters.
Key words: пальмитат аммония, сверхкритический диоксид углерода, растворимость, динамический режим
The solubility of ammonium palmitate in supercritical carbon dioxide is studied in
the dynamic regime at 308.15—333.15 K and 10.0—35.0 MPa. Experimental data are
described in the framework of the Peng—Robinson equation of state.
Key words: переэтерификация, гетерогенные катализаторы, этиловые эфиры жирных кислот, термическое разложение, кинематическая вязкость
Catalytic and non-catalytic transesterification of rapeseed oil in ethanol at supercritical
fluid conditions with exposure to ultrasonic reactive environment are studied at 623—
653 K, 30 MPa and molar «alcohol-to-oil» ratios 12 : 1 and 18 : 1. The effect of
heterogeneous catalysts on the reaction rate us revealed. Correlation between the fatty
acids ethyl esters content in biodiesel and kinematic viscosity of the reaction product
is established.
Key words: растворимость, ИК-спектроскопия, сверхкритические флюиды
A self-consistent approach to the measurement of solubility of biologically active
compounds in supercritical (SC) media based on the infrared spectroscopy is exemplified
by paracetamol in supercritical CO<sub>2</sub>. According to this approach, the integrated extinction
coefficient for a chosen analytical spectral band is determined from additional
spectroscopic measurement of the compound under study dissolved in an inert solvent
at known concentrations in the considered range of the parameters of state (pressure
and temperature — <i>p</i>, <i>T</i> ). The values of solubility of the compound under study in the
SC medium are calculated based on the above obtained values of the extinction coefficient
and the analytical values of the integral intensity of the chosen spectral band for saturated
solutions in the <i>p</i>,<i>T</i>-range of interest. The method allows one to determine the solubility
with a high accuracy even if the measured values are as low as 10<sup>-4</sup>—10<sup>-1</sup> mol.%.
Key words: субкритическая вода, целлюлоза, полиолы, гидролитическое гидрирование, сверхсшитый полистирол, гетерогенный катализ
It is demonstrated that subcritical water is efficient as a medium for the cellulose
conversion process to produce polyols. A novel type of Ru-containing catalysts supported
on hypercrosslinked polystyrene (HPS) is suggested. In the presence of the catalyst
containing 1% Ru the total yield of sorbitol and mannitol reaches 50 %; this is comparable
with the results obtained in the presence of more complex and, therefore, more
expensive catalytic systems. The influence of both the process conditions and the
catalyst properties on the target product yield is studied. The hydrolytic hydrogenation of
cellulose in subcritical water using Ru-containing catalysts can be considered as a basis
for novel technologies of cellulose-containing biomass conversion and production of raw
materials for chemical synthesis and industrial production of second generation biofuels.
Key words: полимерные микрочастицы, инкапсуляция биоактивных компонентов, лекарственные формы пролонгированного действия, сверхкритический диоксид углерода
The process of supercritical fluid encapsulation of pharmaceutical grade risperidon
into bioresorbable D,L-polylactide microparticles by PGSS (Particles from Gas Saturated
Solutions) method is studied. Micronization and change of morphology of risperidon
crystals during its encapsulation into polymer plasticized by supercritical carbon dioxide
is experimentally observed. This finding enabled fabrication of polymer structures of
various dispersion (10—100 μm) and morphologies comprising up to 40 wt.% of
risperidon without any use of organic solvent. The kinetics of risperidon release from
the polymer microparticles into physiological solution is studied by UV-spectrophotometry.
It is shown that the use of different molecular weight D,L-polylactides
enables one to extend the risperidon release time from bioresorbable polymer particles
fabricated by PGSS up to 10 days in a controllable manner.
Transformation of Alkylbenzenes in Oxidizing Medium on ZSM-5 Catalyst under Supercritical Conditions
Key words: алкилбензолы, парциальное окисление, H-ZSM-5
Reactions of substituted benzenes — toluene, p-xylene, fluorobenzene, phenol, cumene
and styrene — with nitrous oxide as an oxidant on H-ZSM-5 catalyst under supercritical
conditions at 345—420°C and 70—150 atm was investigated.</p><p>
It is shown that the products of disproportionation, isomerization and condensation
that do not contain oxygen form predominantly. Only in the oxidation of toluene the
selectivity to oxidation product (cresols) reaches up to 35 %. The yield of corresponding
phenols in oxidation of alkyl-, hydroxy- and fluorobenzenes is negligible. Double bond
conjugated with π-system of benzene rings (styrene), as well as the presence of branched
alkyl substituents (in cumene) and hydroxyl-group (in phenol) hinder the formation
of benzene ring oxidation products.
Key words: ибупрофен, сверхкритический СО<sub>2</sub>, полиморфизм, квантовая химия, молекулярно-динамическое моделирование
The conformational equilibria of ibuprofen in vacuum and in supercritical carbon dioxide
are studied using methods of quantum chemistry and classical molecular dynamics. In
supercritical carbon dioxide ibuprofen forms 12 different conformations, two of them
correspond to the structures of the molecule in the crystal lattice of the first and second
polymorph. It is shown that the GAFF force field allows one to obtain the characteristics
of conformers, almost coinciding with those obtained by quantum-chemical calculations
in the B3LYP/cc-pVTZ level of theory.
Key words: молекулярная ассоциация, растворимость, сверхкритический флюид, метилксантин
Experimental data on solubility of methylxanthines (theophylline and theobromine) in
the system «supercritical (SC) CO<sub>2</sub>-methanol» at various concentrations of methanol
is analyzed in the framework of the ASL (Associated Solution + Lattice) model based
on the molecular association theory and the simple lattice concept. <sup>1</sup>H NMR
spectroscopy is applied to investigate hetero-association of methylxanthines with
methanol at 313 K. The contribution of molecular association to the solubility of
methylxanthines in a mixed SC CO<sub>2</sub>-methanol solvent is discussed. It is shown that the
presence of NH groups in methylxanthine molecule (i.e. theobromine and theophylline
vs. caffeine) leads to the increasing contribution of solubility component related to the
molecular association.