Aqueous Dimethyl Sulfoxide Solutions Research Articles

Evaluation of acute and subacute toxicity of ethanolic extract and fraction of alkaloids from bark of Aspidosperma nitidum in mice

This study investigated the acute and subacute toxicity of the ethanolic extract (EE) and alkaloid fraction (FA) from A. nitidum. The EE was obtained from trunk bark with ethanol, FA was obtained from the fractionation of EE. To test the acute toxicity, mice were divided into four groups, and the negative controls received water or aqueous solution of dimethyl sulfoxide, whereas the others received EE or FA (2000 mg/kg, orally, single dose). The same controls were used in the subacute trial. However, the animals were treated for 28 days, and the dose used was 1000 mg/kg per day of EE and FA. Daily clinical evaluations of the animals were performed. At the end of the experiment, hematological, biochemical, and histopathological assessments (liver, lung, heart, and kidney) were performed. In the acute and subacute toxicity studies, mice treated with EE and FA did not show any clinical changes, there were no changes in weight gain, hematological and biochemical parameters compared to the control groups (p > 0.05). In the histopathological examination, there was no abnormality in the organs of the treated animals. Therefore, EE and FA did not produce toxic effects in mice after acute and subacute treatment.

Enhancement of the round-trip efficiency of liquid air energy storage (LAES) system using cascade cold storage units

In this research, the variation of round-trip efficiency in a liquid air energy storage system (LAES) is calculated and an optimal configuration is found. The multiple stages of cold energy storage are simulated with several materials that process latent heat at different temperature ranges. The effectiveness in the charging and discharging processes of LAES is newly defined, and its relationship with the round-trip efficiency is examined. According to defined correlation, the effectiveness of the discharging process significantly affects the overall system performance. The round-trip efficiency is calculated for the combined cold energy storage materials of aqueous dimethyl sulfoxide (DMSO) solution, ethanol, and pentane theoretically. The performance of LAES varies depending on the freezing point of the cold storage materials. In particular, when the LAES uses several cold storage materials, those materials whose freezing points are close to room temperature and liquid air temperature should be included in the cold storage materials. In this paper, it is assumed that only latent heat is used for cold energy storage, but for more realistic analyzes, the additional consideration of the transient thermal situation to utilize sensible heat is required. In the case of such a dynamic system, since there is certainly more increased heat capacity of the entire storage system, the volume of the cold energy storage system will be greatly reduced.

ON THE KINETICS OF ANODIC PROCESSES AT OXIDATION OF AQUEOUS SOLUTIONS OF DIMETHYL SULFOXIDE

Dimethyl sulfoxide is a feedstock for a large number of organic substances syntheses. Nowadays research is considerably focused on the production of general products of dimethyl sulfoxide oxidation – dimethyl sulfone and methane sulfonic acid. Dimethyl sulfone is well–known as a food supplement for the treating and strengthening of human joints and ligaments. dimethyl sulfone is basically synthesized by oxidation of dimethyl sulfoxide in hot 30 % hydrogen peroxide in glacial acetic acid. Synthesis is accompanied by significant losses of hydrogen peroxide, the target product has to be significantly purified. It becomes possible to control the synthesis of pure dimethyl sulfone and methane sulfonic acid when using the electrochemical method of oxidation of dimethyl sulfoxide in its aqueous solution with chemically resistant anode and high overvoltage of oxygen reaction Controlled synthesis is relevant because sulfur tends to change the oxidation rate. Study of kinetics of anodic processes at platinum electrode was performed in the dimethyl sulfoxide concentration range about 1.0…4.0 mol∙dm–3. Current raise was observed at potentials that are more positive than 1.3…1.4 V. This potential range corresponds to oxygen release. Dissolved sulfuric acid (0.2 mol∙dm–3) was added in order to inhibit the oxygen release and achieve the potential for the formation of peroxide radicals in aqueous solutions of dimethyl sulfoxide. It is known that sulfate ions are adsorbed on the surface of the platinum anode, displacing molecules of protonated water. This allows to shift the potentials and increase of the electrolysis current in 0.2 mol∙dm–3 H2SO4 to 1.7…1.9 V. It indicates the processes of formation of peroxide radicals on the surface of the platinum anode. Further shift of the anode potential into more positive area than 2.00…2.05 V leads to a rapid increase in current density. At such potentials, dimethyl sulfoxide and dimethyl sulfone are oxidized to methane sulfonic acid with a parallel oxygen and hydrogen peroxide release. Current–voltage study has shown that the oxidation of dimethyl sulfoxide in aqueous solutions runs through the formation of dimethyl sulfone. When conducting electrochemical synthesis with control of the anode potential, it is possible to produce dimethyl sulfone without further oxidation to methane sulfonic acid. The addition of 0.2 mol∙dm–3 H2SO4 to aqueous dimethyl sulfoxide solutions inhibits oxygen release and intensifies oxidation of dipole dimethyl sulfoxide molecules adsorbed on the platinum surface. The influence of adsorption processes on the kinetics of anode processes at the platinum anode in aqueous solutions of dimethyl sulfoxide at high anode potentials has been studied.

The pursuit of a more powerful thermodynamic hydrate inhibitor than methanol. Dimethyl sulfoxide as a case study

Search for new, more effective hydrate formation inhibitors is one of the oil and gas industry's urgent tasks. Dimethyl sulfoxide (DMSO) can be considered as a promising anti-hydrate reagent. DMSO and its aqueous solutions were characterized by several physicochemical methods, including measuring their density, viscosity, freezing point, the methane hydrate equilibrium conditions (V-Lw-H), and identification of the hydrate type formed. The hydrate phase equilibria in the system of DMSO aqueous solution–gaseous methane were determined for a wide range of DMSO concentrations (0–55 mass%), temperatures (242–289 K), and pressures (3–13 MPa). X-ray measurements reveal that DMSO does not form double hydrate with methane over the entire concentration range. The data obtained show that DMSO is a thermodynamic hydrate inhibitor. To quantitatively describe the anti-hydrate activity of DMSO, a correlation of thermodynamic depression ΔTh with the mass fraction of DMSO in solution and gas pressure was proposed. It was found that at concentrations above 33 and 53 mass% DMSO becomes more effective THI than the widely used monoethylene glycol and methanol, respectively. Such behavior is associated with the greater non-ideality of DMSO aqueous solutions (negative deviations from Raoult's law) compared to alcohols aqueous solutions. A linear correlation linking the depression of hydrate equilibrium temperature ΔTh and ice freezing point ΔTice was also derived.A comparative analysis of the density and kinematic viscosity of aqueous solutions of DMSO and methanol (0–100 mass%) was performed. It was revealed that DMSO is a promising inhibitor combining high anti-hydrate activity, low volatility (compared to methanol), and acceptable viscosity properties of aqueous solutions.

The pursuit of resin-dentin bond durability: Simultaneous enhancement of collagen structure and polymer network formation in hybrid layers

ObjectiveImperfect polymer formation as well as collagen’s susceptibility to enzymatic degradation increase the vulnerability of hybrid layers over time. This study investigated the effect of new dimethyl sulfoxide (DMSO)-containing pretreatments on long-term bond strength, hybrid layer quality, monomer conversion and collagen structure. MethodsH3PO4-etched mid-coronal dentin surfaces from extracted human molars (n = 8) were randomly treated with aqueous and ethanolic DMSO solutions or following the ethanol-wet bonding technique. Dentin bonding was performed with a three-step etch-and-rinse adhesive. Resin-dentin beams (0.8 mm2) were stored in artificial saliva at 37 °C for 24 h and 2.5 years, submitted to microtensile bond strength testing at 0.5 mm/min and semi-quantitative SEM nanoleakage analysis (n = 8). Micro-Raman spectroscopy was used to determine the degree of conversion at different depths in the hybrid layer (n = 6). Changes in the apparent modulus of elasticity of demineralized collagen beams measuring 0.5 × 1.7 × 7 mm (n = 10) and loss of dry mass (n = 10) after 30 days were calculated via three-point bending and precision weighing, respectively. ResultsDMSO-containing pretreatments produced higher bond strengths, which did not change significantly over time presenting lower incidence of water-filled zones. Higher uniformity in monomer conversion across the hybrid layer occurred for all pretreatments. DMSO-induced collagen stiffening was reversible in water, but with lower peptide solubilization. SignificanceImproved polymer formation and higher stability of the collagen-structure can be attributed to DMSO’s unique ability to simultaneously modify both biological and resin components within the hybrid layer. Pretreatments composed of DMSO/ethanol may be a viable-effective alternative to extend the longevity of resin-dentin bonds.

Элементный состав поверхностных слоев, формирующихся на титане, при катодной обработке в хитозансодержащих воднодиметилсульфоксидных растворах фосфатмолибдатного электролита

It was established that at the cathodic treatment of titanium in aqueous dimethyl sulfoxide solutions of sodium molybdate, containing phosphoric acid, at the potential of the cathodic incorporation of sodium (Ec = −2.6 V) in the potentiostatic mode, the composition formed on the electrode surface layer depended not only on the composition of the solution, but also on the volume ratio of the aqueous electrolyte solution and the organic solvent (dimethyl sulfoxide).

Design and synthesis of a new tripod-chromogenic sensor based on a s-triazine and thiazolidine-2,4-dione ring (TCST) for naked-eye detection of Li+

A novel tripod-chromogenic sensor based on a s-triazine and thiazolidine-2,4-dione ring (TCST) was designed, synthesized, and applied as a colorimetric probe in aqueous solutions of dimethyl sulfoxide (DMSO). The probe showed a highly sensitive and selective colorimetric sensor for naked-eye detection of Li+, changing from colourless to yellow. The probe’s detection limit toward Li+ was found to be 1.2 μM. The result of the Job plot analysis showed 1:1 stoichiometry for the interaction between the tripod chemosensor and Li+ and this result was confirmed by 1H NMR titration experiments. The probe can also be used for biological activities depending on the results of microbial tests.

Growth-inhibiting effect of azoxystrobin and its ability to inhibit sugar consumption in winter wheat sprouts and roots

This study aimed to assess the prospects for the use of azoxystrobin, a fungicide of the strobilurin class, for increasing the resistance of winter wheat to low temperatures. The effect of azoxystrobin on growth processes, cell viability and the content of water-soluble carbohydrates in winter wheat (Triticum aestivum L.), the Ikutskaya variety, was studied. In comparison with other synthetic strobilurins, azoxystrobin is more frequently used in multicomponent fungicidal preparations. Azoxystrobin is a broad-spectrum fungicide that inhibits complex III of the mitochondrial electron transport chain. Experiments were carried out in laboratory conditions using 3-day-old etiolated winter wheat sprouts. The sprouts were grown in a dark place at a temperature of +24 °C on azoxystrobin solutions dissolved in a 0.36% aqueous solution of dimethyl sulfoxide, distilled water and a 0.36% dimethyl sulfoxide solution. The effect of various azoxystrobin concentrations (2.5, 5, 10 and 20 μM) on the growth of sprouts and roots was assessed, along with the viability of sprout and root cells. Azoxystrobin had a concentration-dependent growth-inhibiting effect on sprouts and roots. At concentrations of 2.5 μM and 20 μM, the inhibition degree for sprouts varied from 2.8% to 41.7%, respectively. For roots, these values comprised 34.6 and 63.1%, respectively. The growth-inhibiting effect was not accompanied by a decrease in the cell viability of sprouts and roots, which was assessed using in vivo staining with fluorescein diacetate (FDA). The effect of azoxystrobin at a concentration of 10 μM on the sugar content in germinated sprouts was also evaluated. At this concentration of azoxystrobin, the sugar content was higher by 3.6% in sprouts germinated on a dimethyl sulfoxide solution. Since growth inhibition and sugar accumulation are important factors in plant adaptation to low temperatures, further research into effects of azoxystrobin on the physiological and biochemical parameters of plants associated with the development of low-temperature resistance seems justified.

Determination of residual dimethyl sulfoxide by high-resolution continuum source graphite furnace molecular absorption spectrometry

High-resolution continuum source molecular absorption spectrometry (HR-CSMAS) has been extended to the determination of sulfur-containing organic molecule, on the example of dimethyl sulfoxide (DMSO) as a residual solvent in CH3NH3PbI3 perovskite thin films. For this purpose, DMSO molecules were converted into CS molecules by pyrolysis in a graphite furnace at low temperature and the sulfur content was determined by measuring molecular absorption of CS at 258.055 nm. An aqueous solution of DMSO was used for calibration. A characteristic mass of 17 ng was achieved for S after pyrolysis at 160 °C by using Pd as a chemical modifier. Furthermore, the content of DMSO was normalized to that of Pb whereas the content of Pb was determined by reducing the Pb in the perovskite to metallic Pb with Zn powder and measuring absorption of the weak Pb line at 261.418 nm by high-resolution continuum source atomic absorption spectrometry (HR-CSAAS). The Pb content remained constant whereas the S/Pb molar ratio decreased with increasing annealing time. Our results open new opportunities for the characterization of residual DMSO in wide classes of materials.

Thermochemistry of the Dissolution of L-Threonine in Acetonitrile, 1,4-Dioxane, Acetone, and Dimethylsulfoxide Aqueous Solutions at Т = 298.15 K

The enthalpies of dissolution of L-threonine in acetonitrile, 1,4-dioxane, acetone, and dimethylsulfoxide aqueous solutions are measured via calorimetry at mole fraction of the organic solvent x2 = 0–0.25 and T = 298.15 K. Standard enthalpies of dissolution $${{\Delta }_{{{\text{sol}}}}}H^\circ $$ and transfer $${{\Delta }_{{{\text{tr}}}}}H^\circ $$ of L-threonine from water to a mixed solvent are calculated along with the enthalpy coefficients of pairwise interactions hxy between L-threonine and the solvent molecules. Relationships between the enthalpies of dissolution of L-threonine and the composition of a mixture, the energy of interaction between the components of the mixture, and the electron-donating ability of organic solvents are found. The enthalpy coefficients of the pairwise interaction between L-threonine and other amino acids (glycine, L-alanine, L-valine, and L-methionine) in the mixed solvents are analyzed comparatively. The enthalpy contributions from the side chains of L-amino acids to the energy of interaction with molecules of these organic solvents in an aqueous solution are assessed quantitatively.

Effect of Mixed Water–Acetone Solvent on the Stability of Copper(II) Glycylglycinate Complexes

Potentiometric titration at a temperature of 298 K and ionic strength of solutions of 0.1 (NaClO4) is used to determine the stability constants of normal and deprotonated mono- and bis-glycylglycinate copper(II) complexes in a water–acetone solvent of variable composition. The peptide group dissociation constants of the glycylglycinate copper(II) complex in water–acetone mixtures are calculated using the obtained data. It is found that the stability of all complexes of copper(II) with glycylglycinate ion increases along with the concentration of acetone in the solution. The contributions from the resolvation of reagents in a water–acetone solvent to the change in the Gibbs energy of the formation of copper(II) glycylglycinate are estimated. It is established that the growth of the stability constant of the glycylglycinate copper(II) complex in an aqueous-acetone solution is determined by the weakening of ligand solvation. The results are compared to similar data for the complexation reactions of the glycylglycinate ion with copper(II) and nickel(II) ions in aqueous solutions of ethanol and dimethylsulfoxide.

Confinement Effects on Glass-Forming Aqueous Dimethyl Sulfoxide Solutions.

Combining broadband dielectric spectroscopy and nuclear magnetic resonance studies, we analyze the reorientation dynamics and the translational diffusion associated with the glassy slowdown of the eutectic aqueous dimethyl sulfoxide solution in nano-sized confinements, explicitly, in silica pores with different diameters and in ficoll and lysozyme matrices at different concentrations. We observe that both rotational and diffusive dynamics are slower and more heterogeneous in the confinements than in the bulk but the degree of these effects depends on the properties of the confinement and differs for the components of the solution. For the hard and the soft matrices, the slowdown and the heterogeneity become more prominent when the size of the confinement is reduced. In addition, the dynamics are more retarded for dimethyl sulfoxide than for water, implying specific guest-host interactions. Moreover, we find that the temperature dependence of the reorientation dynamics and of the translational diffusion differs in severe confinements, indicating a breakdown of the Stokes–Einstein–Debye relation. It is discussed to what extent these confinement effects can be rationalized in the framework of core-shell models, which assume bulk-like and slowed-down motions in central and interfacial confinement regions, respectively.

Design and Synthesis of New Tripod-Chromogenic Sensor Based on S-Triazine and Thiazolidine-2,4-Dione Ring (TCST) for Naked-Eye Detection of Li-Ions

A novel tripod-chromogenic sensor contains central nucleus s-triazine and thiazolidine-2,4-dione ring (TCST) was designed, synthesized and applied as colorimetric probes in aqueous solutions of dimethyl sulfoxide (DMSO). The probe showed a highly sensitive and selective colorimetric sensor for naked-eye detection of Li+ ion, with a different color change from colorless to yellow. The probe’s detection limit (LOD) toward Li+ was found to be 1.2 μM. The result of the Job’s plot showed 1:1 stoichiometry for the interaction between tripod-chemosensor and Li-ion that this result was confirmed by 1H NMR titration experiments. The probe can also be used for biological activities depending on the results of microbial tests.

On the crystal structures and phase transitions of hydrates in the binary dimethyl sulfoxide-water system.

Neutron powder diffraction data have been collected from a series of flash-frozen aqueous solutions of dimethyl sulfoxide (DMSO) with concentrations between 25 and 66.7 mol% DMSO. These reveal the existence of three stoichiometric hydrates, which crystallize on warming between 175 and 195 K. DMSO trihydrate crystallizes in the monoclinic space group P21/c, with unit-cell parameters at 195 K of a = 10.26619 (3), b = 7.01113 (2), c = 10.06897 (3) Å, β = 101.5030 (2)° and V = 710.183 (3) Å3 (Z = 4). Two of the symmetry-inequivalent water molecules form a sheet of tiled four- and eight-sided rings; the DMSO molecules are sandwiched between these sheets and linked along the b axis by the third water molecule to generate water-DMSO-water tapes. Two different polymorphs of DMSO dihydrate have been identified. The α phase is monoclinic (space group P21/c), with unit-cell parameters at 175 K of a = 6.30304 (4), b = 9.05700 (5), c = 11.22013 (7) Å, β = 105.9691 (4)° and V = 615.802 (4) Å3 (Z = 4). Its structure contains water-DMSO-water chains, but these are polymerized in such a manner as to form sheets of reniform eight-sided rings, with the methyl groups extending on either side of the sheet. On warming above 198 K, α-DMSO·2H2O undergoes a solid-state transformation to a mixture of DMSO·3H2O + anhydrous DMSO, and there is then a stable eutectic between these two phases at ∼203 K. The β-phase of DMSO dihydrate has been observed in a rapidly frozen eutectic melt and in very DMSO-rich mixtures. It is observed to be unstable with respect to the α-phase; above ∼180 K, β-DMSO·2H2O converts irreversibly to α-DMSO·2H2O. At 175 K, the lattice parameters of β-DMSO·2H2O are a = 6.17448 (10), b = 11.61635 (16), c = 8.66530 (12) Å, β = 101.663 (1)° and V = 608.684 (10) Å3 (Z = 4), hence this polymorph is just 1.16% denser than the α-phase under identical conditions. Like the other two hydrates, the space group appears likely, on the basis of systematic absences, to be P21/c, but the structure has not yet been determined. Our results reconcile 60 years of contradictory interpretations of the phase relations in the binary DMSO-water system, particularly between mole fractions of 0.25-0.50, and confirm empirical and theoretical studies of the liquid structure around the eutectic composition (33.33 mol% DMSO).

Precipitation and Transformation of Vaterite Calcium Carbonate in the Presence of Some Organic Solvents.

In this paper, the production of CaCO3 particles via the carbonation route in the reaction of CaCl2 and CO2, using NH3 as a promoter of CO2 absorption, was studied. The solvents used as the reaction media for CaCO3 precipitation were aqueous solutions of methanol, isopropanol and dimethyl sulfoxide (DMSO), in a concentration range of 0–20% (v/v). It was found that the presence of an organic additive influenced the precipitation rate, the content of vaterite in the obtained product, the morphology and the size of the precipitated CaCO3 particles, as well as the rate of its transformation into calcite. The presence of all added organic solvents reduced the vaterite concentration in the produced CaCO3 both at the end of the reaction and after incubation in the reaction medium for 1 h. However, the transformation of vaterite particles into calcite in the tested solutions was slower when the 4 h and 24 h procedures were compared. The interactions of solvents with calcite and vaterite were compared using HPLC tests. DMSO molecules interacted with vaterite particles the most strongly, while the interaction of isopropanol with this polymorph was the weakest. The opposite effect was observed for interactions with calcite particles, and the affinity decreased in the series: isopropanol, methanol, DMSO.

Cellulose hydrogel skeleton by extrusion 3D printing of solution

Abstract Cellulose is the most abundant natural polymer on earth, which has obtained increasing interest in the field of functional materials development for its renewable, high mechanical performance and environmental benign. In this study, the traditional processing method (wet spinning and film production) of cellulose-based materials was applied by using cellulose solution for 3D printing, which can directly build complex 3D patterns. Herein, a natural cellulose is dissolved in an effective mixed aqueous solution of dimethyl sulfoxide (DMSO) and tetrabutylammonium hydroxide (TBAH). The cellulose solution extrusion was controlled by a modified fused deposition modeling (FDM) 3D printer. During the controlled extrusion 3D printing process, the viscous cellulose solution will gelifies and further solidifies into a predetermined 3D pattern at room temperature in air. Subsequently, a cellulose hydrogel skeleton was obtained, when the 3D pattern was solvent-exchanged with deionized water. Finally, the mechanical and swelling performance of the cellulose hydrogel scaffold was improved by a cross-linking agent treatment method. With treatment of the 3D printed scaffolds in 0.8 wt% cross-linking agent solution, the obtained cellulose hydrogel could absorb 28 g/g water, and the compression strength was 96 kPa. This work provided an efficient way to prepare natural cellulose hydrogel by 3D printing under room temperature.

Specific features of the temperature dependence of tryptophan fluorescence lifetime in the temperature range of −170–20 °C

The temperature dependence of tryptophan fluorescence lifetime in an aqueous solution, aqueous solutions of glycerol (50 and 75 %, v/v) and dimethyl sulfoxide (DMSO) (50 and 75 %), and 1 M aqueous trehalose solution was studied in the range of –170 to +20 °C. In this temperature range, the fluorescence kinetics in all samples is best approximated by three exponential terms with characteristic times τ1 ∼ 3 ns, τ2 ∼ 4 ns, and τ3 ∼ 15 ns at room temperature. Temperature dependences of fluorescence lifetimes for the fastest and medium components exhibited antisymbatic (antiphase) behavior in the temperature range of –60 to 10 °C. To explain this behavior, a model was suggested that takes into account the tryptophan (Trp) molecule transition from the excited state to the state with separated charges – charge transfer state (CTS), the transitions back to the excited state, and the radiative transitions of the CTS to the ground state. Mathematically, this model is equivalent to the model that we have suggested earlier in [Gorokhov et al. (2018) Biochemistry (Moscow), 82, 1615–1623] to describe the transitions between different rotamer forms of tryptophan. The obtained results can be used for interpreting the experimental temperature curves of tryptophan fluorescence lifetime in proteins.

Solubility of d-Histidine in Aqueous Cosolvent Mixtures of N,N-Dimethylformamide, Ethanol, Dimethyl Sulfoxide, and N-Methyl-2-pyrrolidone: Determination, Preferential Solvation, and Solvent Effect

This work mainly focused on d-histidine solubility in N,N-dimethylformamide (DMF) + water, ethanol + water, dimethyl sulfoxide (DMSO) + water, and N-methyl-2-pyrrolidone (NMP) + water mixtures. All experiments were performed at temperatures between T = 293.15 and T = 333.15 K at intervals of 5 K by a shake-flask method. The largest solubility of d-histidine was found in the neat solvents of NMP (DMF or DMSO) for the NMP (DMF or DMSO) mixtures and water for the ethanol mixture. The values of mole fraction solubility were well-correlated using the Jouyban–Acree model, which obtained relative average deviation values lower than 2.78% and root-mean-square deviation values lower than 27.43 × 10–4. We used the inverse Kirkwood–Buff integral method to quantitatively evaluate the local mole fraction of DMF (ethanol, DMSO, or NMP) and water nearby d-histidine. Within the water-rich compositions, d-histidine was preferentially solvated by water for the DMSO and NMP mixtures and by ethanol for the ethanol mixture. Within the other compositions for the three mixtures, d-histidine was preferentially solvated by DMF or NMP in the DMF or NMP + water mixtures and by water in the ethanol + water mixture. Nevertheless, for the aqueous solution of DMSO (1) + water (2) with entire compositions, d-histidine was not preferentially solvated by DMSO or water. Moreover, linear solvation energy relationships were implemented on experimental data to obtain insight into solvent dependence of solubility variation in mixed solvents. It was observed that the basicity of DMSO (NMP and DMF) + water mixtures and the polarity-polarizability of the ethanol + water mixture mainly control the variation in solubility.

Dielectric spectrum and structure of aqueous solutions of dimethyl sulfoxide

Frequency measurements of aqueous solutions of dimethyl sulfoxide (DMSO) were carried out in the range of 0.5-36.5 GHz at temperatures 293-323 K. Relaxation spectra were used to determine dipole relaxation times and the distribution parameter of these times, which were in good agreement with the Cole-Cole model. The thermodynamic characteristics of dipole relaxation and viscous flow were calculated based on the obtained results and found to be similar to the energy characteristics of the hydrogen bond and to have maximum values in the region of 0.3-0.4 mole fractions of DMSO. Kinetics of intermolecular interaction suggesting the formation in mixtures of 1 ∶ 2 and 2 ∶ 1 DMSO-Н2О complexes were studied.

МОДИФІКАЦИЯ ВИСОКОЕНЕРГЕТИЧНИХ РЕЧОВИН, ВИЛУЧЕНИХ З ПРОДУКТІВ УТИЛІЗАЦІЇ ТВЕРДОГО РАКЕТНОГО ПАЛИВА

The main components of high-energy compositions are nitramines: octogen (HMX) & hexogen (RDX). The solution to the problem of the lack of these components is possible through the use of returnable resources, which are obtained using a certain technology for the disposal of solid rocket fuel and ammunition, unsuitable for further use for its intended purpose. The purpose of this research is to develop a crystallization method for octogen extracted from solid rocket fuel and to obtain modified nitramine suitable for use in high-energy compositions (HEC). The parameters of the process of recrystallization of the extracted nitramine from an aqueous solution of dimethyl sulfoxide (DMSO) were determined in the laboratory: the dependence of the average particle size of the substance on the rotational speed of the mechanical stirrer and the cooling rate of the solution. The required crystal size of the modified nitramine is obtained in the process of crystallization with a rotational speed of a mechanical stirrer in the range of 200 – 330 rpm and a cooling rate of an aqueous solution of DMSO not higher than 2 °C / min, it was found. Addition of seed crystals of standard nitramine up to 10 % (by weight) and 0.5 % (by weight) modifier (isomethyltetrahydrophthalic anhydride) positively affects the crystalline form of the modified product with the formation of crystals of predominantly correct isometric form. The resulting modified nitramine has characteristics that satisfy the requirements for use in HЕC.