Preparation and properties of azinium salts of the 2-pyrazoline series

Azinium salts containing pyrazoline fragments have been obtained by the reaction of 2-pyrazolines with aromatic and heteroaromatic aldehydes, acetylacetone, and acetoacetic ester in the presence of H₂SnCl₅ and HBF₄. Reactions of nucleophilic addition to the multiple bonds and also some cycloaddition reactions among the arylidene derivative have been studied. From the azinium salts of a series of -dicarbonyl compounds have been obtained previously unknown enamino carbonyl compounds of the 2-pyrazoline series.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 101–105, January, 1984.     

Stereochemistry of the iodocyclization of unsaturated alcohols

The corresponding tetrahydrofuran derivatives were obtained by iodination of , - unsaturated alcohols containing substituents attached to the -carbon atom. The effect of substituents on the stereochemistry of the products and the rate of iodination of the unsaturated alcohols were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 32–34, January, 1981.     

Theoretical study on structures and stability of C4P isomers

The structures, energetics, spectroscopies, and stabilities of doublet C(4)P isomeric species are explored at the DFT/B3LYP, QCISD, and CCSD(T) (singlet-point) levels. A total of 12 minimum isomers and 27 interconversion transition states are located. At the CCSD(T)/6-311G(2df)//QCISD/6-311G(d)+ZPVE level, the lowest-lying isomer is a floppy CCCCP 1 (0.0 kcal/mol) mainly featuring a cumulenic structure |C=C=C=C=P*|, which differs much from the analogous C4N radical (|*C-C[triple bond]C-C[triple bond]N|). The quasi-linearity and the low bending mode of 1 are in contrast to the previous prediction. The second energetically followed isomer PC-cCCC 3 (14.9 kcal/mol) possesses a CCC ring-bonded to CP. The two low-lying isomers are separated by a high-energy ring-closure/open transition state (26.5 kcal/mol) and thus are very promising candidates for future laboratory and astrophysical detection. Furthermore, four high-energy isomers, that is, two bent isomers CCPCC 2 (68.4 kcal/mol) and CCPCC 2' (68.5 kcal/mol) and two cagelike species 10 (56.0 kcal/mol) and 11 (67.9 kcal/mol), are also stabilized by considerable barriers. The present work is the first detailed potential energy survey of CnP clusters and can provide useful information for the investigation of larger CnP radicals and for understanding the isomerism of P-doped C vaporization processes.     

An efficient procedure for protection of carbonyls in Brønsted acidic ionic liquid [Hmim]BF4

Protection of carbonyls as acetals or ketals using Brønsted acidic ionic liquid [Hmim]BF₄ as catalyst as well as solvent was investigated. Satisfactory results were obtained for the protection of carbonyls as cycloacetals or ketals with diols. The product can be separated conveniently from the reaction system, and the ionic liquid can be reused after removal of water.     

Hydrogen bonding and π–π stacking in 6‐hydroxy­biochanin A monohydrate

In the lattice of the title compound (systematic name: 5,6,7‐trihydroxy‐4′‐meth­oxy­isoflavone monohydrate), C₁₆H₁₂O₆·H₂O, the isoflavone mol­ecules are linked into chains through R₄³(17) motifs composed via O—H⋯O and C—H⋯O hydrogen bonds. Centrosymmetric R₄²(14) motifs assemble the chains into sheets. Hydrogen‐bonding and aromatic π–π stacking inter­actions lead to the formation of a three‐dimensional network structure.     

Synthesis of derivatives of 1, 2, 3, 4-tetrahydro-4-azafluoren-3,9-diones

Cyclization of amides of -carbamido--(indan-1, 3-dione-2-yl) hydrocinnamic acid gives 1-aryl-2-carbamido-1, 2, 3, 4-tetrahydro-4-azafloren-3, 9-dione. Alkaline and acid hydrolysis of these compounds are investigated.     

Hydroxylamine Derivative in Purex Process III. The Kinetics of Oxidation-reduction Reaction Between N,N-diethylhydroxylamine and Neptunium(VI)

The kinetics of oxidation-reduction reaction between N,N-diethylhydroxylamine (DEHAN) and neptunium (VI) in nitric acid media has been studied by spectrophotometry at 25.2 °C. The rate equation is -d[Np(VI)/dt=k[Np(VI)][DEHAN]/[H⁺] found by investigating the influence of concentration, acidity, ionic strength and temperature on the reaction. The rate constant of the reaction k is 23.0±1.8 min^–1 for = 2.0 mol/l. A possible mechanism of reaction has been suggested according to the ESR spectra of nitroxide radical produced in the DEHAN+V(V) system.     

Effects of specific interactions on the anisotropy of crystal structure distortion of [Co(NH3)5NO2]Cl2 under hydrostatic pressure

Using some special experimental techniques for anisotropic refinement of the crystal structure of [Co(NH₃)₅NO₂]Cl₂ at high pressures gave results with an accuracy comparable to that obtained in normal conditions. The anisotropy of lattice compression under pressure is determined by specific interactions in crystals, in particular, by NH-Cl and NH-O hydrogen bonds. The anisotropy of compression at increased pressure is qualitatively distinct from that caused by lowered temperature for the same structure. This difference is also due to specific interactions (hydrogen bonds) in the structure. Institute of Solid State Chemistry, Siberian Branch, Russian Academy of Sciences (Novosibirsk). Novosibirsk State University. Marburg University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 433–447, May–June, 1998. This work was supported by A. Humboldt Foundation.     

Effect of dicyclopentadiene-and diindenezirconocene dichlorides on free-radical polymerization of methyl methacrylate

The effect of zirconocene dichloride and its indene-containing derivative on the radical polymerization of methyl methacrylate initiated by benzoyl peroxide has been studied. The influence of the metallocenes on the kinetic parameters of the process and the average degree of polymerization has been established. Concentration and temperature dependences have been measured for the initial rate of reaction and the average degree of polymerization in relation to the content of the components in the systems. The microstructure of poly(methylmethacrylate) prepared in the presence of the used initiation systems has been determined.     

Facile 5-endo electrophilic cyclization of unsaturated amides with BuOCl/I2

5-Endo iodocyclization of various β,γ-unsaturated amides proceeded smoothly to give the corresponding conjugated iminolactones exclusively in satisfactory yields with the use of ^tBuOCl and I₂ as the reagents, which proved to be much advantageous over the conventional I₂/NaHCO₃.