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With the use of quantum-chemical and kinetic methods, the influence of free amino groups in amine monomers on the rate of their reaction with ethylene carbonate is studied. It was stated that the catalytic effect in diamine appears at the length of the chain of 3–7 atoms. A decrease in activation barriers is associated with the formation of less strained proton transfer and stabilization cycles in transition states. The theoretically found dependence of the rates of aminolysis of ethylenecarbonate on the structure of amines is confirmed experimentally by kinetic measurements. [ABSTRACT FROM AUTHOR]

The influence of the substituents inductive effect and the proton-donor OH group in the substituted cyclocarbonates differing in the alkyl chain length on the activation barrier of their aminolysis reaction, which underlies the process of urethane formation without the participation of isocyanates, has been studied. Account for the solvent molecules has allowed quantitative interpretation of the process regularities. Kinetics of the model aminolysis reaction of a series of monomers in DMSO has been investigated. [ABSTRACT FROM AUTHOR]

A brief overview of works in the field of mechanisms of reactions underlying the green chemistry of polyurethanes is presented. The main attention is paid to the processes of the formation of nonisocyanate urethanes from cyclocarbonates and amines and the thermal decomposition of acyl azides as a phosgene-free method for the preparation of isocyanates in statu nascendi. The results of the study of the functional composition of cyclocarbonate-containing triglycerides the derivatives of soybean and sunflower oils, and the prospects for using renewable plant raw materials for the synthesis of new urethanes are also discussed. [ABSTRACT FROM AUTHOR]

We investigated the distribution of mitochondrial lineages of two species—the common roach Rutilus rutilus and Ponto-Caspian roach R. lacustris—in the broadest zone of their secondary contact, the Volga basin. For the purpose of species identification, we applied the approach of multiplex PCR based on species-specific divergences in sequences of the first subunit of cytochrome oxidase (COI) of mtDNA. A total of 1120 samples from 82 localities are analyzed. The distribution of certain mitochondrial lineages and their sympatric co-occurrence clarified for the Volga basin. Our study shows that R. rutilus is significantly predominant in the Upper Volga, while the Middle and Lower Volga is dominated by R. lacustris. The various hypotheses of formation of the broad spatial pattern of secondary contact are discussed. [ABSTRACT FROM AUTHOR]

Trends in the influence of a proton-donor solvent on the reaction of aminolysis of ethylene carbonate, which proceeds through concerted and stepwise mechanisms, are studied. The study is based on kinetic data of model reactions in alcohol solutions and results of DFT quantum chemical calculations of reaction paths that involve hydrogen-bonded transition states and intermediates containing different numbers of solvent molecules in the proton-transfer and stabilization cycles. The calculated data on the activation energies of the reaction, which includes cycles of different sizes, indicate that the stepwise mechanism is preferable compared to the concerted one when the reaction proceeds in methanol. The activation barrier of the stepwise path of the reaction is lower by 2.9 kcal/mol than that for the concerted path. Only the proton-transfer cycle is essential for the progress of the reaction, and the presence of a stabilization cycle does not lead to a decrease in the activation barrier. [ABSTRACT FROM AUTHOR]

The comparative reactivity of oleic, linoleic, and linolenic fragments of vegetable oil triglyceride chains in the processes of their conversion to the corresponding hydroxyurethanes is studied. According to DFT quantum-chemical calculations, the linolenic fragments of triglyceride chains are the most reactive. The activation barriers of reactions involving the second cyclocarbonate group of the linoleic fragment and the second and third cyclocarbonate groups of the linolenic fragment are lower than the conversion barriers of first cyclocarbonate groups of the corresponding models, which is explained by the catalytic assistance of the OH groups of hydroxyurethanes, which are formed at the first stage of aminolysis, to the proton transfer act. [ABSTRACT FROM AUTHOR]

Epoxy- and cyclocarbonate-containing oligomers are synthesized by oxidizing sunflower oil and subsequent catalytic carbonization via reaction with carbon dioxide. Using mass spectrometry, it is shown that oligomers, which are triglycerides of epoxy- and cyclocarbonate-containing carboxylic acid derivatives, are characterized by a wide distribution over composition, reflecting the entire set of components contained in natural raw materials. It is found that oligomers derived from sunflower oil contain 16 types of triglycerides in various combinations in contrast to 25 types of triglycerides contained in soybean oil-based oligomers. At the same time, the reactivity of both oligomers as the main representatives of renewable plant materials for new urethanes, which is evaluated by studying the n-butylaminolysis model reaction, is approximately the same. [ABSTRACT FROM AUTHOR]

A brief review of studies in the kinetics, catalysis, and reaction mechanisms of new green chemistry processes for polyurethanes performed at the Semenov Institute of Chemical Physics of the Russian Academy of Sciences over the past decade and a half is given. The review centers on the formation of hydroxyurethanes without the use of isocyanates on the basis of the reaction of cyclic carbonates with amines, the phosgene-free production of isocyanates by thermal decomposition of acylazides, and the prospects for using renewable plant-based raw materials for the production of novel polyurethanes. [ABSTRACT FROM AUTHOR]

A comparative study of kinetic patterns has been carried out for the reaction of cyclocarbonate groups of oligomers and model compounds with n-butylamine in dimethylsulfoxide. The objects of study were ethylene carbonate, monofunctional 4-(2-ethylhexyloxymethyl) cyclocarbonate, trifunctional tricyclocarbonate of polyoxypropylene triol, and an oligomer based on soybean oil triglycerides with an average functionality of ~4.5. The most active compound is ethylene carbonate, whereas cyclocarbonate groups of the oligomer based on soybean oil triglycerides exhibit the lowest reactivity. All the reactions studied proceed via two parallel reaction pathways involving one and two amine molecules, respectively, and the second pathway contributes more to the observed rate of urethane formation. The dependence of the activation energy of aminolysis on the inductive effect of substituents in the model 4,5-substituted 1,3-dioxolane-2-ones has been established by DFT quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Sequences of mitochondrial (cytochrome b) and nuclear (recombination activating gene 1- RAG1) DNA markers were obtained for two species of the genus Alburnoides, the Taskent riffle minnow A. oblongus Bulgakov 1923 and the Terek spirlin A. gmelini Bogutskaya and Coad 2009. Phylogenetic analysis revealed that A. oblongus belongs to the genus Alburnus. [ABSTRACT FROM AUTHOR]

The kinetic regularities and the mechanism of the catalytic action of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, which is the most active of the known catalysts for the formation of hydroxyurethanes from cyclocarbonates and amines, were studied using the example of the n-butylaminolysis of ethylene carbonate. In contrast with the noncatalytic reaction, which proceeds via two parallel pathways that involve one and two molecules of amine, the catalytic reaction follows a single pathway: the second molecule of amine is replaced by a molecule of the catalyst that accelerates the process in accordance with the mechanism of bifunctional catalysis. Different reaction pathways were studied by quantum chemical calculations based on the density functional method. It was shown that the high activity of 1,5,7-triazabicyclo[4.4.0]dec-5-ene results from the formation of a planar cation-like form of the catalyst. Moreover, the low-energy transition between the cation and the initial 1,5,7-triazabicyclo[4.4.0]dec-5-ene enables the catalyst to simultaneously be a good donor and acceptor of protons. This study presents a new way for finding among bifunctional organic compounds the catalysts that are even more active in the reaction of cyclocarbonates with amines. [ABSTRACT FROM AUTHOR]

The genus Rutilus is a widely distributed lineage of cyprinids and ranges from West Europe to East Siberia. Although matrilineal phylogeny and phylogeography of western species were already studied, roaches from remaining part of the range were not examined. Phylogenetic analysis based on cytochrome b sequences detected the following three major phylogenetic clades: (i) R. frisii, (ii) R. rutilus s. str., and (iii) group of six Ponto-Caspian taxa: R. caspicus, R. heckelii, R. rutilus aralensis, R. rutilus lacustris, R. schelkovnikovi, and R. stoumboudae. Our results suggest that these 'species' within Ponto-Caspian clade could be a single species ( R. lacustris by priority of description). The Ponto-Caspian clade is most widely distributed among others and covers the freshwaters from the Aegean Sea basin to Laptev Sea tributaries. Both R. rutilus s. str. and Ponto-Caspian clades sympatrically occur in Black Sea and Caspian Sea basins, Azov Sea itself, and even in drainage of White Sea. The vastest zone of contact (approximately 1700 km) was detected in the Volga basin. The spatial pattern of haplotype diversity and the shape of haplotype network argued for multiple refugia in Ponto-Caspian region as well as a rapid post-glacial colonization of Volga River and Siberia. [ABSTRACT FROM AUTHOR]

A pronounced pleiotropic effect of thyroid hormones on the regulation of gene expression in fish in postembryogenesis was demonstrated for the first time using larvae and juveniles of the blue bream Ballerus ballerus as an example. Genome-wide transcriptome sequencing (RNA-seq) identified 1212 differentially expressed genes in the brain and liver of fish kept in triiodothyronine solution (0.25 ng/mL). Our data show that the regulation of gene expression by thyroid hormones is widespread in nature: it involves not only the structural genes but also the regulatory genes. A significant number of genes under the control of thyroid hormones are involved in the determination of morphological traits. [ABSTRACT FROM AUTHOR]

The synthesis of cyclocarbonate-containing oligomers for non-isocyanate polyurethanes via the catalytic reaction of carbon dioxide with epoxidized soybean oil has been described. It has been shown via the mass-spectrometric method that the oligomers, which are triglycerides of epoxide- and cyclocarbonate-containing derivatives of carboxylic acids, are characterized by an extremely wide composition distribution, reflecting almost the entire set of components contained in natural raw materials. The presence of 25 types of triglycerides of unsaturated (oleic, linoleic, and linolenic) and saturated (stearic and palmitic) carboxylic acids in various combinations in oligomers has been found. The functionality of oligomers at epoxy and cyclocarbonate groups and the problems of the use of plant raw materials for the synthesis of non-isocyanate polyurethanes are discussed. [ABSTRACT FROM AUTHOR]

Test systems using multiplex PCR and restriction analysis have been designed for the simple and rapid identification of two widespread species of roach, Rutilus rutilus and R. lacustris, characterized by the sympatric zone. This method is based on the variation of nucleotide sequences of the mitochondrial markers (cytochrome oxidase I subunit and cytochrome b); it allows identifying the species omitting the DNA sequencing. [ABSTRACT FROM AUTHOR]

The mechanism of bifunctional catalysis by acetic acid in the addition reaction of amines with cyclocarbonates was studied by the DFT (PBE/TZ2P) method. Several one-step and multistep reaction pathways were found. The barrier for the transformation through the most favorable pathway in the presence of acetic acid was shown to substantially decrease (to ∼12 kcal mol) compared to the non-catalytic reaction (∼33 kcal mol) and the reaction involving the second amine molecule as the catalyst (∼22 kcal mol). The kinetics of the model reaction of ethylene carbonate with butylamine in dioxane was experimentally studied, and it was found that the effective activation energy decreases to 5.3 and 1.1 kcal mol for the channels involving one and two amine molecules, respectively, compared to the reaction in the absence of acetic acid (14.0 and 3.7 kcal mol). [ABSTRACT FROM AUTHOR]

The kinetic features of a model reaction of the formation of nonisocyanate urethanes from cyclic carbonates and amines have been determined through the use of the example of the interaction of ethylene with n-butylamine in n-butanol and dioxane at different temperatures. The reaction proceeds via two parallel routes involving one or two amine molecules with an activation energy of 7.0 or 2.5 kcal/mol, respectively, in n-butanol and 14.0 or 3.7 kcal/mol in dioxane. The relative contributions of these routes to the observed reaction rate depend on the amine concentration and the temperature. In accordance with the density functional theory, the activation barriers have been calculated and data on the structures of the transition states and the role of the proton-donor solvent in the reaction mechanism have been obtained. [ABSTRACT FROM AUTHOR]

Methods for increasing the activity of polymer catalysts of urethane formation via their heterogenization in solutions have been developed. The kinetic features have been studied for model reactions carried out in the presence of catalysts containing Bu3SnO(O)C groups at the ends of poly(ethylene glycol) chains in the solvent-precipitant system, initially heterogeneous organotin catalysts based on the styrene-maleic anhydride copolymer crosslinked by divinylbenzene, and a modified silica gel prepared by the surface grafting of tributyltin acetate groups. Unlike the use of monomeric organotin catalysts of urethane formation, whose catalytic activity attains a plateau with an increase in their concentration in solutions, the use of heterogeneous catalysts results in linear dependences of the reaction rate on the concentration of catalytic centers. [ABSTRACT FROM AUTHOR]

Evidence for the structural effect of liquids associated by hydrogen bonds on the kinetics of molecular reactions was experimentally found. The kinetics of hydrolysis of (phenylaza)phenyl isocyanate in water–dioxane mixtures was studied at various temperatures and in the presence of structure-making and structure-breaking additives. The apparent order γ of reaction with respect to water concentration increased with temperature because of the partial breaking of the H-bond solution structure. It was found that the value of γ was affected by salt additives, for which positive (Et4NCl) or negative (KI) hydration is typical. This hydration resulted in strengthening or partially breaking the H-bond structure of water, respectively. It follows from the kinetic data that the addition of 0.1 mol/l Et4NCl was equivalent to a decrease in the solution temperature by 6 to 7°С, whereas the addition of 0.1 mol/l KI was equivalent to an increase in the temperature by 5 to 6°С. The effect of poly(ethylene oxide) additives (which stabilize the structure of water) on the value of γ was similar to the effect of the tetraethylammonium salt, which is characterized by positive hydration. [ABSTRACT FROM AUTHOR]

Pharmacokinetics of sydnocarb upon the joint administration with ladasten was investigated in rats. Being introduced in this combination, sydnocarb was detected in the blood plasma for a longer time, showed higher values of the distribution coefficients in organs and tissues, and was characterized by a higher bioavailability (112,5%) than upon separate administration in the same dose. [ABSTRACT FROM AUTHOR]

The effects of 5 benzodiazepines on basal and K+-induced Ca2+ concentration in synaptoneurosomes from intact and stressed C57B1/6 and BALB/c mice were studied in vitro. Membrane depolarization induced by low KCl concentrations produced different effects on Ca2+ accumulation by synaptoneurosomes from two mouse strains. Benzodiazepines applied in vitro exerted no effects on Ca2+ influx. In synaptoneurosomes from both C57B1/6 and BALB/c mice exposed to emotional stress diazepam in a dose of 5 mg/kg reduced the basal and K+-induced Ca2+ accumulation. [ABSTRACT FROM AUTHOR]