Reactions of the IO· radical resulting in hydrogen atom abstraction from halogen-containing molecules

A jet-stream kinetic technique and the resonance fluorescence method applied to detection of iodine atoms were used to measure the rate constants of the reactions of the IO^· radical with the halohydrocarbons CHFCl-CF₂Cl (k = (3.2 ± 0.9) × 10^?16 cm³ molecule s^?1) and CH₂ClF (k = (9.4 ± 1.3) × 10^?16 cm³ molecule s^?1), the hydrogen-containing haloethers CF₃-O-CH₃ (k = (6.4 ± 0.9) × 10^?16 cm³ molecule s^?1) and CF₃CH₂-O-CHF₂ (k = (1.2 ± 0.6) × 10^?15 cm³ molecule s^?1), and hydrogen iodide (k = (1.3 ± 0.9) × 10^?12 cm³ molecule s^?1) at 323 K.     

Chemical equilibrium of esterification in AcOH-EtOH-H2O-EtOAc system at 293.15 K

New experimental data on the chemical equilibrium of esterification in an acetic acid-ethanol-water-ethyl acetate system at 293.15 K and atmospheric pressure are presented.     

Formation of active species in spark discharge and their possible use

The chemical effects of self-sustained spark discharge with an energy per pulse of 5.9 × 10⁻² J, a pulse repetition frequency of 10 Hz, and a spark-gap breakdown voltage of 6 kV have been studied. The discharge generated a UV photon flux of (2.5 ± 0.3) × 10¹⁵ cm⁻² s⁻¹ with an energy density of (2 ± 0.3) × 10⁻³ J cm⁻¹ s⁻¹ and the emission spectrum maximum at 220 nm. The action of the discharge on water samples leads to a decrease in pH and to buildup of oxidizing and reducing species. The formation of HO₂^· radicals with an initial yield of (1.2 ± 0.3) × 10⁻⁶ mol L⁻¹ s⁻¹ has been detected in the liquid. The initial yields of acid residues (increment in [H⁺]), oxidants, and reducing agents are (5.8 ± 1.6) × 10⁻⁷, (3.3 ± 1) × 10⁻⁶, and (4.2 ± 1) × 10⁻⁷ mol equiv L⁻¹s⁻¹, respectively. The formation of NO₃⁻ and NO₄⁺ ions, nitrosamines, and organic compounds has been established.     

Absorption spectra and the nature of complexes in the polyvinyl Alcohol-Nickel (II) chloride system

We have used electronic spectroscopy in the 160–1100 nm range to study the polyvinyl alcohol-nickel(II) chloride system. Based on the results obtained, we hypothesize formation of mixed-ligand complexes of the type [Ni(H₂O)_6-nCl_n]^2-n (n = 0, 1,..., 5) in the polyvinyl alcohol matrix. Transformation of the coordination sphere as the NiCl₂ concentration changes is apparent both in the region of the d-d transition bands (350–1100 nm) and in the region of the charge transfer bands (160–250 nm). We propose assigning the absorption bands separated by mathematical treatment to complexes of specific compositions. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 136–138, January–February, 2006.     

Melt synthesis and structural properties of opal-V2O5 and opal-VO2 nanocomposites

A method has been proposed for filling bulk and film opals with V₂O₅ and V₂O₅: W melts under the action of capillary forces. The VO₂ and VO₂: W (1.8 mol %) compounds have been synthesized from the V₂O₅ and V₂O₅: W precursors in opal pores. The phase composition and morphology of the nanocomposites prepared have been investigated. It has been revealed that, in the opal-V₂O₅ composite, the filler compound has a texture formed by the directional crystallization of the melt in pores of the opal film. The tunable photonic crystal heterostructure opal/opal-VO₂ has been synthesized using liquid chemical etching.     

Structure and photochemical properties of 2-(N-benzoyl-N-phenylaminomethylene)- and 2-(N-p-nitrobenzoyl-N-phenylaminomethylene)-3(2H)-benzo[b]thiophenones

Conclusions It was established by x-ray crystallographic investigation that the inhibition of the photochromism of the nitro derivative (IIb) compared with compounds (I) and (IIa) is due to the difference in the structure of the molecules and to the realization of the low-lying triplet n^* state, due to the presence of the p-nitro group. The flattening of the p-nitrobenzoyl fragment and its rotation from the plane of the molecule evidently promote localization of the photoexcitation energy in this conjugated fragment of the molecule and lead to nonradiative deactivation of the excited S^1* state by intercombination conversion through the n triplet state and, finally, to a marked decrease in the yields of the fluorescence and the phototransformations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1544–1548, July, 1989.The authors are grateful to M. I. Knyazhanskii for assistance in the discussion of the results.     

Experimental Evidence for Acceleration of Reaction between Iodine Monoxide and Chlorine Monoxide at the Reactor Surface

The reaction of iodine monoxide with chlorine monoxide resulting in atom escape to the gas phase is studied at T = (303 ± 5) K and P = 2.5 Torr using a flow setup for measuring the resonance fluorescence signals of atomic iodine and chlorine. The heterogeneous reaction between chlorine monoxide and iodine monoxide occurring at the reactor surface covered with an F32-L Teflon-like compound and treated by the reaction products is characterized by the rate constant k = (4.9 ± 0.2) × 10^–11 cm³ molecule^–1 s^–1. This value is substantially higher than the rate constant for the homogeneous reaction IO^· + ClO^· (k ₁ 1 × 10^–12 cm³ molecule^–1 s^–1).