The use of polarized light scattering for the study of the dynamics of the spinodal decomposition

Due to the fact that in a system undergoing spinodal decomposition the long wavelength fluctuations are enhanced, we expect that multiple events can be observed when the passage of light through the sample is measured. We study here the intensity of double scattering for both polarized and depolarized measurements, as a function of time and angle of detection. The time dependence is nonexponential and the dependence on the scattering wave vector is less pronounced than in the case of single scattering. For systems with spherical molecules it is possible to separate double and single scattering contributions if both polarized and depolarized measurements are made. This increases the amount and quality of information about the dynamics of the spinodal decomposition that can be obtained from light scattering experiments.     

Structure and Vibrational Spectra of 1:1 Chloranilic Acid (CLA)—Tetramethylpyrazine (TMP) Complex

In searching for new molecular materials the crystals of 1:1 complexes of tetramethylpyrazine (TMP) with chloranilic acid (CLA) were grown. In the crystalline lattice of TMP.CLA infinite chains of hydrogen bonded components are formed. Very strong (d_(O·sN) = 2.692(2) {?}) hydrogen bonds without proton transfer are present. The components of the complex form stacks of parallel arrangement with the distance typical of van der Waals interaction. One can conclude that in packing, interactions via hydrogen bonds play a decisive role. In the IR spectrum one observes a broad, continuous absorption with well resolved trio typical of strong hydrogen bonds. A detailed analysis of IR and Raman spectra in the low frequency region related to deformation vibrations of CH₃ groups shows that strong interaction via hydrogen bonding only slightly affects the dynamics of these groups.     

Manganese Complexes with Octaphenyltetraazaporphine: Acid–Base Interactions and Kinetic Stability in Proton-Donor Solvents

Complexes of manganese(III) and manganese(V) with octaphenyltetraazaporphine (H₂OPTAP) were synthesized. Acid–base interactions of these complexes in the CH₂Cl₂–CF₃COOH system and kinetics of their dissociation in concentrated sulfuric acid, as well as kinetics of octaphenyltetraazaporphine destruction in sulfuric acid solutions were studied by spectrophotometric methods. Acid–base interactions in CH₂Cl₂–CF₃COOH were shown to involve two macrocyclic meso-nitrogen atoms in succession. Concentration stability constants of the acid forms obtained pK ₁ = 0.29 ± 0.01 and pK ₂ = –0.62 ± 0.08 for (chlorine)manganese(III)octaphenyltetraazaporphine ((Cl)MnOPTAP); pK ₁ = 0.99 ± 0.02 and pK ₂ = – 0.70 ± 0.03 for (nitrido)manganese(V)octaphenyltetraazaporphine ((N)MnOPTAP). The rate of dissociation of the complexes in 94–98% H₂SO₄ does not depend on the acid concentration. The manganese(V) complex is three times as stable as the manganese(III) complex.     

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.     

Transesterification of fatty acid ethoxylates in supercritical methanol, then gas chromatography-mass spectrometric determination of the derived methyl esters, for identification of the initiators

Unknown fatty acid ethoxylate samples have been transesterified in supercritical methanol, using a loop made of a stainless-steel tubing as the reactor vessel. The initiator acids, now present as the corresponding methyl esters, were determined by gas chromatography-mass spectrometry (GC-MS). Quantitative transesterification is achieved by heating a solution of the ethoxylate sample in methanol at 280 degrees C for 10 min under pressure. The influence of reaction time, temperature, and presence of a Lewis acid catalyst has been investigated. The method of transesterification was optimized in respect of low cost, short reaction time, and availability to laboratories with standard analytical equipment.     

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.     

Synthesis and properties of amides of 2-substituted 3-aryl- and 3-pyridylaminoacrylic acids

The reaction of aryl- or pyridylamines with ethyl orthoformate and malonanilic acid gave amides of 2-(N-arylcarbamoyl)-, 2-cyano-, 2-ethoxycarbonyl-3-arylaminoacrylic acids and their corresponding 3-pyridyl analogs. IR and PMR spectroscopy indicates that these compounds exist in the enamine form with strong intramolecular hydrogen bonds. Amides of 3-(2-pyridylamino)-2-ethoxycarbonylacrylic acid cyclize to give amides of pyrido[1,2-a]pyrimidine-3-carboxylic acid, which react with hydrazine hydrate to give amides of 3-aminopyrazole-4-carboxylic acid.Perm Pharmaceutical Institute, 614000 Perm. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 629–633, May, 1994. Original article submitted February 8, 1994.     

Phase coexistence overlap induced by steric interactions

Novel phase diagram calculations, in which the two phase-separated regions of polymer stabilized colloidal suspensions overlap under certain constraints of the reduction in the range of the steric interaction with increasing temperature, are presented. A phase diagram displaying liquid-vapour, liquid-solid and vapour-solid coexistence with two triple points, but no critical points is shown to exist in qualitative agreement with observations.     

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).     

1-Alkoxyaziridines

The corresponding 1-alkoxyaziridines were synthesized by oxidation of methoxy-, ethoxy-, and isopropoxyamines with lead tetraacetate in the presence of 2-methyl-2-butene and 2,3-dimethyl-2-butene. The PMR spectra of the oxidation products were investigated, and the high pyramidal stability of nitrogen in these compounds was confirmed. The individual invertomers 1-alkoxy-2,2,3-trimethylaziridines were isolated by preparative gas-liquid chromatography.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1514–1519, November, 1972.The authors thank A. A. Potekhin, I. N. Somin, R. R. Kostikov, M. I. Komendantov, and M. A. Kuznetsov for their useful discussions.