Aqueous Alcoholic Medium Research Articles

Assessment of the influence of glycol and alcohol on the morphology and protective properties of iron carbonate in carbon dioxide corrosion of gas pipelines

The potential effect of hydrate formation inhibitors (glycols, alcohols) — components of the liquid phase of gas pipeline operating media — on carbon dioxide corrosion during the transport of aggressive gas has not been sufficiently studied. The paper presents the results of a study of the corrosive effect of glycol (alcohol) present in the liquid phase on the composition and properties of corrosion products on steel when modeling the main aggressive factors under conditions of transport of CO2-containing gas. On a corrosion stand, the aggressive conditions of alternating wetting of gas pipeline walls with water were reproduced. The fluid circulation characteristic of a partially filled pipeline can have an effect on preventing the formation or destruction of films of corrosion products (iron carbonate, siderite) on the steel surface. In places of cracking and peeling of siderite formed in the presence of CO2, conditions will be created for the formation of general and local corrosion damage. During simulation tests, monoethylene glycol and isopropanol, as well as their aqueous solutions of different concentrations, were used. For the first time, data on the formation and composition of non-stoichiometric siderite in water-glycol and water-alcohol media at CO2 partial pressures and temperature were obtained. By processing diffraction patterns obtained by X-ray diffraction, the degree of substitution of iron ions in non-stoichiometric siderites by other cations was determined. The dependence of the degree of substitution on the concentration of alcohol (glycol) in their aqueous solutions was analyzed. It was revealed that with an increase in glycol concentration, a decrease in the rate of local corrosion is observed. With a high glycol content, internal corrosion is completely suppressed in the presence of CO2. It has been established that in aqueous-alcoholic media at elevated temperatures, local carbon dioxide corrosion does not occur. This is apparently due to the uneven distribution of water and alcohol in the mixture. The results obtained can be used in assessing internal carbon dioxide corrosion in the presence of glycol (alcohol), used at gas facilities as an inhibitor of hydrate formation.

Основной и побочный процессы при восстановлении 1-(2-нитроарил)-1Н-бензотриазола

The paper investigates the HCl concentration impact on the main and by-processes during the reduction 
 of 1-(2-nitroaryl)-1H-benzotriazole by tin (II) chloride in acidic aqueous-alcoholic medium. The authors have observed the formation of azoxy compounds in addition to the target amino derivative at low HCl content in the reaction mass. The use of 36% hydrochloric acid causes the alkylation of the formed amino compound with alcohol as a solvent.

Main and by-processes at 1-(2-nitroaryl)-1H-benzotriazole reduction

The paper investigates the HCl concentration impact on the main and by-processes during the reduction of 1-(2-nitroaryl)-1H-benzotriazole by tin (II) chloride in acidic aqueous-alcoholic medium. The authors have observed the formation of azoxy compounds in addition to the target amino derivative at low HCl content in the reaction mass. The use of 36% hydrochloric acid causes the alkylation of the formed amino compound with alcohol as a solvent.

Synthesis and Characterization of Novel Isoxazole derivatives

Twenty five novel Isoxazole heterocycles are synthesized and characterized by IR, NMR and CHN analysis. Physico-chemical characteristics also notified. In the first step chalcones are synthesized by the reaction of aromatic aldehydes with aromatic ketones in aqueous alcoholic alkaline medium. These are made to react with hydroxylamine hydrochloride and sodium acetate to prepare title compounds. All synthesized compounds analyzed for obedience of Lipinsky’s rule. Six of the compounds showed slight violation to oral dosage form suitability. Most of the compounds were solid in nature and gave good yield.

Sol-Gel-Derived Functional Coatings for Pre-Sowing Seed Treatment

The superatomic structure of film-forming sols obtained by the acid hydrolysis of tetraethoxysilane (TEOS) in an aqueous medium (free of organic solvents) was studied using the SAXS method. The formation of nanoparticles (NPs) was confirmed in alcohol-free silica sols with both a low (1 vol. %) content of TEOS and a high (10 vol. %) content of TEOS, hydrolyzed in an aqueous-alcoholic medium. A trimodal size distribution was revealed for the resulting NPs, with radii ranging from less than 1 nm to ~11 nm. The volume fraction of NPs tends to grow with increases in TEOS concentration, as well as with the introduction of magnetic NPs of iron oxides into silica sols. The synthesized silica sols and suspensions based on silica sols with FexOy NPs were used for the pre-sowing treatment of white and cauliflower cabbage seeds in order to provide a functional coating on their surfaces, thereby improving seed germination, stimulating their growth in the early stages of development, and suppressing the effect of phytopathogens. The effect of the pre-sowing seed treatment in sol-gel compositions on seed germination and the growth characteristics of plant seedlings is analyzed, including the influence of iron-oxide magnetic NPs’ compositions and concentrations in silica sols.

Arylazopyrazole linked Schiff bases as organocatalysts for the ipso-hydroxylation of arylboronic acids for the synthesis of phenols

A simple metal-free strategy for the synthesis of phenols from aryl and hetero aryl-boronic acids using arylazopyrazole linked o-hydroxyl Schiff base has been illustrated. These sustainable ipso-hydroxylations have very short reaction times, using aqueous H2O2 as the oxidant in aqueous-alcoholic medium. The current protocol has been demonstrated to be effective with a variety of electron-rich and electron-deficient aromatic substrates and provides access to a wide range of phenols. This is the first time that an azoyrazole linked Schiff base has been used to increase the nucleophilicity of H2O2, in oxidative hydroxylation reactions.

Synthesis and properties of 6-(2,6-dichlorophenyl)-3- (3-methyl-1H-pyrazol-5-yl)-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazine-7-carboxylic acid and its salts

Carboxylic acids and their derivatives are an important component of many biological processes. For example, they can be used to create new medicines that can be useful in the fight against various diseases. Additionally, compounds containing a thiazole moiety may possess beneficial properties in practical pharmacy. The incorporation of this heterocyclic structure in molecules can positively impact several biological characteristics, such as anti-inflammatory, antiviral, and antifungal activities. Consequently, exploring novel compounds that combine a thiazole fragment with a carboxyl group holds promise for the advancement of new drugs and diagnostic tools that can contribute significantly to the battle against numerous diseases. The aim of the work was to create a number of organic and inorganic salts of 6-(2,6-dichlorophenyl)-3-(3-methyl-1H-pyrazol-5-yl)-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-7-carboxylic acid and study of their properties, as well as selective determination of the biological potential of these compounds. Materials and methods. The synthetic part of the study involved the sequential synthesis of the original compound 4-amino-5-(3-methyl-1H-pyrazol-5-yl)-1,2,4-triazole-3-thiol using a well-established method described in previous articles. The next stage involved the reaction of thiol with 2,3-dichlorobenzaldehyde in a medium of glacial acetic acid. The resulting Schiff base was subsequently reacted with 2-chloroethanoic acid in tetrahydrofuran in the presence of an equimolar amount of sodium hydride. Salts of the corresponding acid were formed during the reaction of 6-(2,6-dichlorophenyl)-3-(3-methyl-1H-pyrazol-5-yl)-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-7-carboxylic acid with both organic and inorganic bases in an aqueous-alcohol medium. The structures of all synthesized compounds were determined using 1H NMR spectroscopy and elemental analysis. Additionally, the individuality of each compound was confirmed using high-performance liquid chromatography-mass spectrometry. Results. The study determined the optimal conditions for the formation of both organic and inorganic salts of 6-(2,6-dichlorophenyl)-3-(3-methyl-1H-pyrazol-5-yl)-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-7-carboxylic acid. The analysis of pharmacokinetic parameters and physicochemical properties using ADME (absorption, distribution, metabolism, and excretion) allowed for the identification of promising synthesized compounds and the selection of more optimal compounds for further investigation. Conclusions. The structure of 12 compounds was synthesized and confirmed. Physical-chemical and pharmacokinetic analysis of ADME parameters was carried out and promising compounds were selected for more in-depth research.

Heterocyclization of 2-nitrobenzoyl1,1,3,3-tetracyanopropenides by the action of hydrogen chloride in alcohol

The interaction of 2-[3(4)-nitrobenzoyl]-1,1,3,3-tetracyanopropenides with hydrogen chloride in alcohols leads to the corresponding 4-amino-1-alkoxy-1-[3(4)-nitrophenyl]-3-oxo-6-chloro-2,3-dihydro-1 H -pyrrolo[3,4- c ]pyridine-7-carbonitrilam, through the formation of intermediate 2-{2-hydroxy-2-[3(4)-nitrophenyl]-4-cyano-5alkoxy-1,2-dihydro-3 H -pyrrole-3-ylidene}malononitriles, which can be isolated in low yield. Carrying out the reaction in an aqueous-alcoholic medium makes it possible to obtain 4-amino-1-hydroxy-1-[3(4)-nitrophenyl]3-oxo-6-chloro-2,3-dihydro-1 H -pyrrolo[3,4- c ]pyridine-7-carbonitriles.

3-Pyrrolyl BODIPY Based Schiff Base Fluorophores: A Selective Chemodosimetric and Optical Sensor for Diethyl Chlorophosphate.

Diethyl chlorophosphate (DCP), an organophosphate, is utilized as a pesticide, herbicide, and for various other applications. Despite many uses of organophosphates, the organophosphates are noxious and harmful substances, and their selective detection is a critical concern in the context of the environment, physiology, and social security. In a methodological quest, here we have synthesized two Schiff base compounds 1 and 2 by introducing the hydroxyl group at the α-position of 3-pyrrolyl BODIPY either directly as hydroxylamine 1 or at the ortho position of aryl ring as 2-aminophenol 2. Both compounds 1 and 2 exhibited high selectivity and high sensitivity for DCP over other pesticides in the aqueous-alcoholic medium at physiological pH. This occurs via nucleophilic phosphorylation of the hydroxyl group, which resulted in both compounds exhibiting two different optical signals following the structure-function correlation of the pyrrolyl BODIPY systems. Upon binding DCP, compound 1 showed a quenching in the optical spectrum because of phosphorylation of hydroxyl group whereas compound 2 exhibited enhancements in both absorption and fluorescence spectra because of hydroxyl phosphorylation followed by intramolecular cyclization. Furthermore, the fluorescent microscopy experiments also indicated that the compound could be used as a fluorescent compound for sensing DCP in plant tissues.

Blue light-induced iniferter RAFT polymerization in aqueous-alcoholic media as a universal tool for the homopolymerization of various monomer families: kinetic investigations on different scales

Influence of batch dimensions and blue light intensity on the kinetics of the photo-iniferter RAFT polymerization of four different monomers is investigated.

Toward functionalization without functional agents: An X-ray photoelectron spectroscopy study

Changes to the surface composition of hydroxyapatite were measured after incubations in water, in ethanol or in a mixed aqueous-alcoholic medium. Ethanol decreased the surface presence of calcium ions in direct proportion to its amount in the medium. Because of its lower polarity than that of water, ethanol also increased the interfacial energy, in response to which the surface relaxed by rearranging into a more disordered state, as indicated by the increase in the heterogeneity of both calcium and oxygen electronic states. Accordingly, the binding energy of core-level oxygen electrons consistently increased with the concentration of ethanol and was compensated for by the decrease of the corresponding binding energies in calcium atoms, attesting to the weakened ionic bonds at the interface. The weakened ionic bonds increased the metallicity of the calcium ion, which prompted the offset of the valence band edge determined by the Ca4s electron energy state toward the Fermi level and the conduction band, thus shrinking the band gap and increasing the electrical conductivity of the surface. The surface energy reduction entailing the partial loss of the crystalline order at the surface predisposed the nanoparticles incubated in alcoholic media for diminished sorption of proteins, but also for an augmented osteogenic response. These results demonstrate that surface functionalization of materials for various physicochemical and biological effects could be achieved without the use of chemical ligands. Rather, more economical design techniques stemming from the repertoire of materials science and engineering could be employed with equally satisfactory outcomes.

Combined In Silico and Experimental Investigations of Resveratrol Encapsulation by Beta-Cyclodextrin.

The results of the computational and the physicochemical studies of the encapsulation of resveratrol with β-cyclodextrin are presented here. At first, the molecular docking experiments predicted good binding. Several MD simulations and MM-PBSA experiments confirmed the reliable binding, showing optimal kinetics and energy. As an application, resveratrol inclusion complexes with β-cyclodextrin were obtained in an aqueous alcohol medium via microwave treatment. The results of thermographic measurements of the obtained clathrates using a differential scanning calorimeter are presented, and the obtained activation energy was calculated using the Ozawa–Flynn–Wall and Friedman methods, as well as nonparametric kinetics. The effect of complexation on the kinetic parameters of thermal destruction of the β-cyclodextrin–resveratrol inclusion complex was considered. The morphology of the surface of the obtained clathrate complexes was described using a scanning electron microscope. The spectral properties of the inclusion complex were characterized by FT-IR, 1H, and 13С NMR spectroscopic data. The obtained in silico, morphological, thermogravimetric, and spectral results confirmed the formation of the resveratrol–β-cyclodextrin complex. The antioxidant activities of the inclusion complex were determined to be 12.1 μg/mL, compared to 14.3 μg/mL for free resveratrol, indicating an improvement in the bioactivity.

Modification of Cellulose Textile Materials with Zinc-Oxide Nanoparticles and Investigation of Their Antibacterial Properties

Methods for the synthesis of nanoparticles (NPs) of zinc oxide in an aqueous-alcohol medium are described. Using scanning electron microscopy (SEM), it is shown that NPs with a size of 5–49 nm are formed. Optimal conditions for the treatment of cellulose materials with aqueous solutions of zinc-oxide NPs are developed. SEM studies confirm the presence of zinc-oxide NPs on the surface of cellulose materials, which are rather unevenly distributed. Antimicrobial activity is assessed by the degree of inhibition of bacterial growth (Escherichia coli) on materials treated with zinc-oxide NPs compared to the control samples. Cellulose materials modified with zinc oxide NPs are shown to have antibacterial activity against bacteria and molds.

Multicomponent synthesis of novel dihydropyrano-dioxine fused-bicyclic systems as a potentially new class of heterocyclic atropisomers

A new series of dihydropyrano-dioxine products were synthesized via one-pot combination of 2,2-dimethyl-1,3-dioxan-5-one with aromatic aldehydes and malononitrile. The first step occurs rapidly in an aqueous alcoholic medium at reflux, followed by nucleophilic addition of malononitrile to the olefinic site of the intermediate and iodine induced oxidation to the final products, which directly precipitate in the vessel, avoiding time consuming and expensive chromatographic separations. The structure of the products was elucidated based on their NMR data and verified by X-ray crystallography. In the case of α-substituted derivatives, rotational barrier caused by the bulk of the ortho substituent led to the formation of atropisomeric products. To study this aspect, molecular geometry of 4 g was optimized by ChemDraw professional 20 and then MM2 calculation was performed.

Technology for obtaining a deposited catalyst based on an aluminosilicate matrix modified with europium oxide

The number of cars used worldwide is constantly growing. In this regard, the problem of combating atmospheric pollutants - exhaust gases of internal combustion engines is of particular relevance. Over the years, automakers have made many improvements to car engine design and fuel systems to meet pollution limits. One of the best solutions to this problem is the use of a so-called catalytic converter (converter) or simply a catalyst with a high content of noble metals, the main function of which is the simultaneous oxidation of unburned hydrocarbons and CO, as well as the reduction of nitrogen oxides. It was found that the addition of rare earth metals to Pd, Pt catalysts improves their properties and reduces the proportion of noble metals in the composition of catalysts. The paper presents the results of a study of complexation in the Eu3+-ligand system, where the ligand is an organic acid, by photocolorimetric and potentiometric methods. In the Eu3+-gallic acid system, a stable complex of the composition MeLnx – 1:2 is formed. In the Eu3+- oxalic acid system, a stable complex of the composition MeLnx – 1:1 is formed. In the Eu3+-valine system, a stable complex of the composition MeLnx – 1:2 is formed. A new technique for obtaining complex compounds is shown, consisting in adding hydrogen peroxide H2O2 to a solution containing solutions of Eu3+ salt and organic acid in an aqueous-alcoholic medium to block the reduction of Eu3+→Eu2+. A technology for obtaining a automotive catalyst has been developed, consisting of successive stages: obtaining complex compounds, applying the obtained complex compounds to ceramic block matrices, drying, applying platinum (palladium) acid, calcination. The presence of the Eu3+ ion in the ceramic matrix is proved by the method of elemental analysis. The technology can be applied to solve the problem of environmental pollution, such pollutants as exhaust gases of cars containing a lot of harmful substances in their composition.

Preparation of encapsulated α-tocopherol acetate and study of its physico-chemical and biological properties

The article discusses the results of research for obtaining encapsulated vitamin E using a water-soluble oligosaccharide (cyclodextrin). The inclusion complexes of β-CD with α-tocopherol were obtained in an aqueousalcoholic medium by coprecipitation and microwave activation. The highest yields of target clathrate inclusion complexes of vitamin E with cyclodextrin were obtained under microwave synthesis conditions. Molecular modeling of inclusion complexes of α-tocopherol acetate with β-cyclodextrin in the ratios of 1:1, 1:2, 1:3, and 1:4 was performed using the MM+ method. Based on semi-empirical PM3 calculations, without taking into account the influence of the environment, the total energy of the systems under study was estimated. Data on the study of the structure of the clathrate complex of α-tocopherol acetate with β-cyclodextrin was presented. The surface morphology of the resulting “guest-host” clathrate complex was described using a scanning electron microscope. The spectral properties of the inclusion complex were characterized by FT-IR and 1H and 13C NMR spectroscopy data. The study of the 1H NMR and 13C NMR spectra of β-CD in the free and bound state in the form of the β-CD: VE clathrate made it possible to reveal the displacements of the signals of the nuclei (± ∆δ) 1H and 13C of the host molecule both in the region of weak and strong fields. The experimental results confirmed the possibility of the formation of inclusion complexes of α-tocopherol acetate with β-cyclodextrin at various ratios. The data on the study of the effect of encapsulated α-tocopherol acetate on the safety of food meat products was presented.

ИНКАПСУЛЯЦИЯ МАСЛЯНОГО РАСТВОРА ВИТАМИНА АЕВИТ β-ЦИКЛОДЕКСТРИНОМ

The present work aimed at encapsulation of fat-soluble vitamin Aevit (vitamins A and E, oil) with β-cyclodextrin. Inclusion complex of vitamins A and E with β-cyclodextrin was prepared in an aqueous alcohol medium by ultrasonic treatment. The surface morphology of the resulting clathrate inclusion complexes was described using a scanning electron microscope. The results of thermographic measurements on a differential scanning calorimeter are presented. The spectral properties of the inclusion complex are characterized by 1H and 13C NMR spectroscopy data. The experimental results confirmed the existence of a complex of inclusion of β-cyclodextrin with vitamin Aevit (2:1). The activation energy of the thermooxidation destruction reaction of the clathrate complex β-cyclodextrin:vitamin Aevit was calculated, kinetic parameters of thermal destruction of clathrate were determined. These parameters were determined based on the Freeman-Carroll, Sharpe-Wentworth, Ahar and Coates-Redfern methods. The use of the above models made it possible to graphically establish the thermodynamic parameters of the thermal decomposition of β-cyclodextrin and its clathrate with vitamin. The data of thermographic measurements on a differential scanning calorimeter showed that the thermal destruction of the Aevite clathrate with β-cyclodextrin begins with the removal of water molecules from the β-cyclodextrin cavity, then the “guest” substance and the cyclic oligosaccharide are destroyed.

Visible Light Assisted Synthesis of 5-Aryl-1,2,4-thiazolidine-3-thiones Under Catalyst-free Condition

Light energy can be considered as an ideal eco-friendly source of energy for green chemistry. This perspective was used to synthesize 5-aryl-1,2,4-thiazolidine-3-thiones derivative as a quick, efficient and highly improved protocol. The present method developed an energy competent and integrated technique by one-pot condensations of aromatic aldehyde and thiosemicarbazide under the catalyst-free condition in aqueous-alcoholic media. The impact of light on reaction along with mechanical stirring provided a prominent yield of the product. The mild reaction conditions, short reaction time and easy workup procedure, avoidance of heavy metal catalyst and harsh reaction conditions make this protocol greener.

Kinetics Study of Dye Decolorization by Oxidation in Aqueous and Aqueous Alcohol Medium

The kinetics of oxidation of methylene blue with potassium bromate was investigated by observing decolorization of methylene blue in aqueous, aqueous methanol and aqueous isopropanol solvent system. The rate of reaction was studied as function of concentrations of methylene blue and potassium bromate in acidic medium at temperature 303 and 313 K. The increase in concentration of potassium bromate enhances the rate of decolorization of methylene blue in acidic medium; no significant change in rate was observed with variation of methylene blue. The rate of decolorization was found to be fastest in aqueous methanol compared to aqueous isopropanol and slow in aqueous medium. From the investigation, it was observed the reaction follows pseudo-first-order kinetics. The kinetic data were used to propose the mechanism of reaction. Thermodynamic parameters, enthalpy of activation (ΔH*), entropy of activation (ΔS*) and Gibbs free energy of activation (ΔG*), were also calculated to support kinetic results.

Spectral study of thione-thiol tautomerization of thiourea in aqueous alcohol solution

In this work we studied the equilibrium of thione–thiol tautomerization by Raman and UV spectroscopies. This type of tautomerization influences on the course and direction of the reaction between thiourea and other organic compounds. The studies were carried out in water and aqueous alcohol medium. Мethanol, ethanol, propanol-1 and propanol-2 were used as alcohols. Hydrochloric acid was used to protonate thiourea in water and aqueous alcoholic solutions. UV spectroscopy made it possible to establish the tautomer ratio in water and aqueous alcohol solutions as the ratio of the intensities of absorption bands at 236 and 200 nm. There is an increase in the content of the thiol form and a decrease of the thione form observed in the row water-methanol-ethanol-propanol-isopropyl alcohol. The addition of hydrochloric acid to the thiourea water or aqueous alcohol solutions leads to the increase of the thione form and to the decrease of the thiol form in the composition. The thione form of thiourea can be determine by Raman spectra of –C=S group. The thiol form of thiourea is difficult to detect by Raman spectroscopy due to the overlap of the –S–H bond absorption band with alcohols absorption bands.