Bimetallic Alkoxides of Barium and Zirconium: Preparation of BaZrO3 Powder

Complex formation in solutions of barium and zirconium alkoxides in ROH (R=i-Pr, Et) was studied. A number of bimetallic complexes were isolated, and their structure and properties were studied. The sol-gel method yields a single-phase BaZrO₃ powder only wheni-PrOH solutions of the alkoxides are used. In this case, the oxocomplex, BaZrO(OPr-i)₄.(1–2)i-PrOH, is the precursor of the mixed oxide.     

Influence of the structure of monoalkyl substituted ketenes upon the rate of their spontaneous hydrolysis in water

The kinetics of spontaneous hydrolysis of monoalkylsubstituted ketenes has been studied. The influence of inductive and steric effects of substituents upon the rate has been quantitatively estimated in terms of -analysis. Increasing length and branching of alkyl substiuents decrease the rate of ketene hydrolysis.     

Effect of Ultrasonic Field on the State of Starch Hydrogels

Some fundamental aspects of how the primary structure of starch hydrogels with concentration of 1 to 8 wt % disintegrates in an ultrasonic field are discussed. The effect of ultrasonic vibrations on the basic characteristics of starch hydrogels: degree of grain cleavage, viscosity, transparence, and phase composition, is analyzed.     

Synthesis and structure of copper(II) complexes with diaminodioxime (H<Subscript>2</Subscript>L), a derivative of the monoterpenoid (+)-3-carene

Copper(II) compounds with the optically active diaminodioxime (H₂L) derived from the monoterpenoid (+)-3-carene, Cu(H₂L)(NO₃)₂ H₂O (I), Cu(H₂L)(ClO₄)₂ H₂O (II), Cu(H₂L)Br₂ H₂O (III), and Cu(H₂L)SO₄0.5H₂O (IV) with µ_eff equal to 1.81, 1.79, 1.71, and 1.8 µ_B, respectively, were prepared. Studies of the complexes by IR and EPR spectroscopy showed that I and II are mononuclear ionic complexes. Compound III apparently has polymeric structure (the CuN₄Br₂ coordination unit). According to EPR data, the Cu²⁺ ions in polycrystalline compounds III and IV undergo exchange interactions.Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 897–900.Original Russian Text Copyright © 2004 by Larionov, Myachina, Sheludyakova, Boguslavskii, Tkachev, Bizyaev.     

Thermodynamic parameters for the molecular inclusion reaction of dulcin with beta-cyclodextrin. spectrofluorimetric determination of dulcin

The inclusion of dulcin in alpha- and beta-cyclodextrin has been studied by fluorescence spectroscopy. To quantitatively describe complex formation between the beta-cyclodextrin and dulcin, an association constant of 290 M(-1) at 21 degrees was obtained. The thermodynamics associated with the complex formation between dulcin and beta-cyclodextrin in aqueous solution has been studied. The obtained value of DeltaG(0) = -13.7 kJ/mole at 21 degrees , together with DeltaH(0) = -33.6 +/- 2.3 kJ/mole and DeltaS(0) = -67.2 +/-8.3 Jmole(-1) K(-1) indicate that dulcin has a very marked tendency to associate with beta-cyclodextrin in water. The inclusion complex of dulcin in beta-cyclodextrin has been used to determine dulein in the range 0.13-5 mug/ml the method has been applied to determine dulcin in soft drinks.     

Evaluation of the thermochemical changes in agricultural by-products and in the carbon adsorbents obtained from them

The thermochemical decomposition of waste products from a coconut (Cocos nucifera L.), a nut (Juglans regia L.) an apricot (Armeniaca vulgaris L.), an almond (Amygdalus communis L.var amara DC.), a grape (Vitis vinifera L.) and a cherry (Prunus avium L.), as raw materials for producing carbon adsorbents, was investigated by DTA and TG. The thermo-oxidative and decomposition processes resulting in increased number of oxygen-containing functional groups of phenolic and carbonyl type are responsible for the high adsorption capacities of the carbon adsorbents. The thermochemical changes in adsorbents based on agricultural wastes are similar to those in commercial activated carbons. The adsorbents derived from apricot stones have the highest overall thermal stability.     

Stereoisomerism of N-(1-Propenyl)thiobenzamide

A prototropic rearrangement of N-prop-2-enylbenzocarbothioamide afforded two stereoisomeric N-prop-1-enylbenzocarbothioamides (IIa, b) isolated as individual compounds. The stereoisomerism is due to hindered rotation around thioamide bond C(S)-N and also to -diastereoisomerism. The configuration of the isolated isomers was investigated by IR spectroscopy, AM1 and PM3 methods. In the molecules occurs the p,-conjugation with participation of nitrogen atom and multiple bonds resulting in formation of a united delocalized MO in the planar fragment C(S)-NC = C.     

Infrared spectra of negative ions with a strong,symmetric hydrogen bond (HO...H...OH)− and (H3CO...H...OCH3)−

From the multiple attenuated total internal reflection (MATIR) infrared spectrum of an aqueous KOH solution, the spectrum of the (HO)₂H^– ion, formed by a strong, symmetric H-bond, has been segregated. The spectrum of the analogous ion (CH₃O)₂H^– has been segregated from the MATIR infrared spectrum of a solution of KOCH₃ in methanol. The segregated spectra contain large numbers of individual bands that are not present in the spectra of the original components of the solution. This may be a consequence of strong interaction of vibrations of the proton in the central strong, symmetric hydrogen bond with vibrations of other groups in the ion.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1363–1366, June, 1991.     

HPLC Determination of some antibilharzial antimonials by extraction of antimony

The antimonial drug (antimony potassium tartrate, antimony piperazine tartrate or antimony lithium thiomaleate) in aqueous solution or biological fluid is treated with sodium diethyldithiocarbamate in the presence of a suitable masking reagent, the pH is adjusted to 9 +/- 0.5. and the antimony complex extracted with n-hexane and determined by reversed-phase HPLC with an ODS column and detection at 254 nm. The limits of detection are 20 ng (for antimony potassium tartrate and antimony lithium thiomaleate) and 16 ng (for antimony piperazine tartrate).