Solvent effect on the enthalpy of solution and partial molar volume of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate

Enthalpies of solution and partial molar volumes of the ionic liquid 1-butyl-3- methylimidazolium tetrafluoroborate were determined in 15 solvents of different polarity. Very large differences of the enthalpies of solution (Δ ΔsolHIL = 38.9 kJ·mol -1) and partial molar volumes (ΔVIL = 43 cm 3·mol -1) are nearly the same as observed for lithium perchlorate solutions. These results clearly indicate that the low values of the macroscopic polarity parameters of [bmim]BF 4 do not correspond with the large differences of the intermolecular interactions in IL solutions. The values of the partial molar volume of the cation, V [bmim]+, were estimated for the first time. The changes of the partial molar volumes, V IL, reflect mainly the changes of anion volume, V BF4. The rate of the Diels-Alder reaction of 9,10- dimethylanthracene with maleic anhydride in the [bmim]BF 4 medium was nearly the same as in common molecular solvents. © Springer Science+Business Media, LLC 2012

Homo-Diels-Alder reaction of a very inactive diene, bicyclo[2,2,1]hepta-2, 5-diene, with the most active dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione. Solvent, temperature, and high pressure influence on the reaction rate

Solvent, temperature, and high pressure influence on the rate constant of homo-Diels-Alder cycloaddition reactions of the very active hetero-dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione (1), with the very inactive unconjugated diene, bicyclo[2,2,1]hepta-2,5-diene (2), and of 1 with some substituted anthracenes have been studied. The rate constants change amounts to about seven orders of magnitude: from 3.95.10-3 for reaction (1+2) to 12200 L mol-1 s-1 for reaction of 1 with 9,10-dimethylanthracene (4e) in toluene solution at 298 K. A comparison of the reactivity (ln k2) and the heat of reactions (r-nH) of maleic anhydride, tetracyanoethylene and of 1 with several dienes has been performed. The heat of reaction (1+2) is -218 ± 2 kJ mol-1, of 1 with 9,10-dimethylanthracene -117.8 ± 0.7 kJ mol-1, and of 1 with 9,10-dimethoxyanthracene -91.6 ±0.2 kJ mol-1. From these data, it follows that the exothermicity of reaction (1+2) is higher than that with 1,3-butadiene. However, the heat of reaction of 9,10- dimethylanthracene with 1 (-117.8 kJ mol-1) is nearly the same as that found for the reaction with the structural C=C counterpart, N-phenylmaleimide (-117.0 kJ mol-1). Since the energy of the N=N bond is considerably lower (418 kJ/bond) than that of the C=C bond (611 kJ/bond), it was proposed that this difference in the bond energy can generate a lower barrier of activation in the Diels-Alder cycloaddition reaction with 1. Linear correlation (R = 0.94) of the solvent effect on the rate constants of reaction (1+2) and on the heat of solution of 1 has been observed. The ratio of the volume of activation (V≠) and the volume of reaction (V r-n) of the homo-Diels-Alder reaction (1+2) is considered as "normal": V≠/Vr-n = -25.1/-30.95 = 0.81. Copyright © 2012 John Wiley & Sons, Ltd

Enthalpies of solution and partial molar volumes of magnesium perchlorate in alcohols and salt effect of acceleration of the Diels-Alder reaction

Densities and enthalpies of solution at 25°C were measured for dilute solutions of magnesium perchlorate (MP) in some alcohols using the Anton Paar DSA 5000M vibrating tube densimeter and differential calorimetric measurements. In all studied solvents the solution of MP was highly exothermic and large solvent volume contraction was observed. Maximum effect was obtained in methanol and ethanol solutions. Acceleration effect of the Diels-Alder reaction of 9,10-dimethylanthracene with acrylonitrile (in medium of acrylonitrile) in the presence of salts LiClO4, Mg(ClO4)2 and GaCl3 was as 18:160:59,000. © 2011 Elsevier B.V

Studying the effect of high pressure on the cycloaddition reactions of maleic anhydride and substituted anthracenes

The kinetics (rate, activation, and volume) of the high-pressure (up to 2500 bar) Diels-Alder reactions of maleic anhydride with 9-phenylanthracene and 9,10-dimethylanthracene in toluene is investigated. © 2013 Pleiades Publishing, Ltd

Anomalies in the change of volumetric parameters of the Diels-Alder reaction in solution

In this article negative values of the activation volume in retro-Diels-Alder reactions are interpreted in terms of the different possibilities of penetration of the solvent molecules into the sterically branched structures of the adduct and activated complex. Empty spaces, inaccessible to penetration of solvent molecules, lead to increases of the molar volume of the screened adducts in solution and, consequently, to a less negative value of the Diels-Alder reaction volume. The values of partial molar volumes of anthracene, maleic anhydride and the adducts cyclopentadiene-maleic anhydride, anthracene-maleic anhydride and anthracene-tetracyanoethylene, in several solvents, were calculated from the solution density data. © Springer Science+Business Media, LLC 2012

Survey of Epizootiologic and Epidemiologic Situation on Brucellosis in the Russian Federation in 2013; Prognosis for 2014

Carried out is the analysis and assessment of epizootiologic and epidemiologic situation on brucellosis in the Russian Federation over the year 2013. It is demonstrated that on the grounds of tense epizootic situation there is a tendency to reduction in brucellosis morbidity rates among the population. Incidence rates in the North-Caucasian and Southern Federal districts remain high due to B. melitensis spp. brucellosis agent circulation. However, realization of a complex of brucellosis prophylactic measures in the territory of the Republic of Dagestan has resulted in a considerable reduction of a number of primary cases in the region. In addition, forecasted is stabilization of brucellosis morbidity rates among the population and farming animals in 2014, being estimated at 320-370 cases a year

Thermograms of High-Frequency Capacitive Discharge Between Solid and Liquid Electrodes

© 2018, Pleiades Publishing, Inc. Abstract: We present the experimental results on thermograms and plots of temperature distributions along the streamer and spark discharges in a high-frequency capacitive field between solid and liquid electrodes for different electrode geometries

Why can the Diels-Alder reaction of 9,10-diphenylanthracene with 4-phenyl-1,2,4-triazoline-3.5-dione pass by an abnormal way?

9,10-Diphenylanthracene reacts with dienophile by 1,4-positions rather than 9,10-ones of trivial anthracenes, that has been justified with estimation of kinetic and thermodynamic parameters of the process. © 2013 Mendeleev Communications. All rights reserved

A clinical case of a combination of chickenpox and idiopathic thrombocytopenia in a child

The purpose of the study is to describe a clinical case of chickenpox complicated by idiopathic thrombocytopenia.Цель исследования – описание клинического случая ветряной оспы, осложненной идиопатической тромбоцитопенией

THE STUDY OF GENETIC DIVERSITY OF BRUCELLA STRAINS ISOLATED IN THE NORTH CAUCASIAN FEDERAL DISTRICT

Objective of the study is to investigate genetic diversity of Brucella strains of various species, isolated from humans and small mammals in the territory of the North Caucasus Federal District using MLVA14, as well as to identify the correlation between the formed clusters and the place setting, the time setting, and object of isolation.Materials and methods. Carried out has been MLVA14 genotyping of 91 Brucella spp. strains isolated from patients, small mammals and live-stock animals. The sizes of amplicons were compared with MLVA Bank 5.0 database, tutorial version 1.6. Based on the data obtained, constructed was a dendrogram of phylogenetic interrelations of the studied strains. Results and conclusions. Using the data on MLVA genotyping, the studied strains were subdivided into 61 MLVA14 genotypes. Strains of B. suis, B. abortus, B. melitensis form separate clusters in the dendrogram. Strains isolated during cluster cases of brucellosis in humans have similar MLVA14 B. melitensis types, B. suis strains are confined to the epizooties among small mammals that may occur in different administrative territories. The data can be used for monitoring of brucellosis agent, including as an effective tool for retrospective epidemiological analysis