Rate and Equilibrium of Acetyl Group Exchange between Pyridines and Pyridine N-Oxides

22 Acetyl group exchange reactions between N-acetoxypyridinium salts and 4-dimethylaminopyridine, 4-morpholinopyridine, and N-methylimidazole in acetonitrile at 298 K have been studied. The rate constants varied from 10⁵ to 10^–4 L/mol·s, and the equilibrium constants ranged from 10⁹ to 10^–9. The rates and equilibrium constants of these reactions did not comply with the Brönsted equation. The kinetics of the acetyl exchange reactions are well described by a correlation equation containing squared terms.     

Synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]‐pyrimidine‐6‐carboxamides

Possible approaches to synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]pyrimidine‐6‐carboxamides 4 have been discussed. It is shown that the preferable approach is cyclization of 2‐iminocoumarin‐3‐carboxamides 1 , utilizing 5‐amino‐3‐methyl‐N²‐arylthiophene‐2,4‐dicarboxamides 2 as binucleophilic reagents. The proposed procedure allowed us to easily obtain 4 in two stages, using common reagents. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:341–346, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20303     

Ion Mobility Spectrometry of Imidazole and Possibilities of Its Determination

Journal of Analytical Chemistry - The drift time and ion mobility of imidazole are determined and a procedure for the mathematical processing of spectra is developed. The specific features of...     

Luminescent Properties of the Surface of ZnS–Mn Nanocrystals Obtained by Self-Propagating High-Temperature Synthesis

Journal of Applied Spectroscopy - Luminescence of nanocrystalline ZnS–Mn powder obtained by self-propagating high-temperature synthesis is studied. The luminescence was excited by chemical...     

The Investigation of the Medieval Russian Bronze Reliquary Cross Pendant Using a Complex of Nondestructive Methods

Crystallography Reports - The medieval Russian bronze reliquary cross pendant was investigated using a complex of nondestructive methods in order to determine the degree its integrity and identify...     

The Use of the Major Component (Solvent) As an Internal Standard in the Gas-Chromatographic Determination of Impurities

A gas-chromatographic method was proposed for determining impurities using the major component as an internal standard. This method exhibits sufficiently high performance characteristics.     

Multilayer structures with optical characteristics controlled by a magnetic field

The consideration of the gyromagnetic properties of multilayer structures with one or more magnetically active components shows that the application of a magnetic field to such structures imparts magnetically controlled optical properties to them. The effect of a magnetic field on the reflection coefficient of the multilayer structures manifests itself in two phenomena: a shift of the maximum of the spectral curve of the resonant reflection coefficient and a change (increase or decrease) in the bandwidth of this curve. The more pronounced of these two effects is the change in the bandwidth of the spectral curve of the reflection coefficient. The orientation (transverse or longitudinal) of the magnetic field applied to the multilayer structure determines important specific features of these effects. Calculation performed for two types of multilayer structures (Y₃Fe₅O₁₂?Gd₃Ga₅O₁₂ and Y₃Fe₅O₁₂?SiO₂) shows the possibility of their practical use, for example, in fiber optics.     

Dynamics of optical self-amplification of holograms in photopolymeric materials

The proposed theoretical model describes the dynamic optical self-amplification of holograms in amorphous photopolymeric materials with photopolymerization and diffusion. Analytic solutions of the cross-coupled writing and diffraction equations are obtained. Computer-modeling results are used to analyze kinetic aspects of hologram optical amplification, the transformation of the amplitude-phase field of the holographic gratings in space and time, and the evolution of the spectrum-angular sensitivity of the amplification process. Tomsk State Academy of Control Systems and Radioelectronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 81–91, January, 1997.