A hydrogen rearrangement of formamidine and the solvent effects thereupon

The nature of the 1,3 hydrogen rearrangement of formamidine (H₂N-CH=NH) and the solvent effects on that reaction are studied with ab initio molecular orbital calculations on the basis of the supermolecule model. The reaction path and the motion of the migrating hydrogen atom are traced by using the concept of the intrinsic reaction coordinate (IRC). Four types of orientation of one water molecule to formamidine at the transition state of reaction are examined and the results are discussed from the standpoint of the orbital interactions.     

Preparation and properties of molybdenum and tungsten dinitrogen complexes : `XVI. Electrochemical properties of tungsten and molybdenum diazoalkane complexes

Diazoalkane complexes of type [MF(NNCRR′)(dpe)₂][BF₄] (M = Mo or W; dpe = Ph₂PCH₂CH₂PPh₂), which are easily derived from bis(dinitrogen) complexes [M(N₂)₂(dpe)₂], undergo consecutive one- and two-electron oxidations and reductions under voltammetric conditions at a platinum electrode. The ESR spectra of the species generated by the controlled potential electrolysis show that primary oxidation occurred on the metal atom (M = Mo) and reduction on the two nitrogen atoms in the diazoalkane ligands (M = Mo or W).     

Oxidation of aromatic hydrocarbons with oxygen in a radiofrequency plasma

The reactions of three aromatic hydrocarbons, benzene, toluene, and styrene, with oxygen in a radiofrequency (r) plasma were investigated. Benzene was oxidized to yield phenol as a single volatile organic product. Similarly, toluene gave the ring oxidation products, cresols, as well as considerable amounts of methyl oxidation products, consisting mainly of benzaldehyde and benzyl alcohol. In contrast, the oxidation of styrene took place predominantly on the olefinic double bond to produce styrene oxide On basis of the products and effects of reaction variables, r power and flow rates of hydrocarbons and oxygen, on the reaction rate, the oxidation mechanism was discussed, particularly focusing on the intermediate species responsible for the formation of major products.     

Sensor design for development of tribo-electric tomography system with increased number of sensors

Electrodynamic sensor, which can also be called as tribo-electric sensor, senses the electrostatic charge carried by the particle. The tomography system using electrodynamic sensor is called as tribo-electric tomography system. Source of the signal induced on the electrodynamic sensor is brought by the object to be measured and no excitation circuit is necessary. This electrodynamic sensing is a passive sensing and the fast and light weighted tomography system is expected. On the other hand, most of tomography system, like capacitance tomography or resistance tomography, demands excitation circuit and is an active sensing. The number of measurements with the passive sensing is equal to the number of sensors and that of active sensing is the number of the combinations of two sensors. The passive sensing tomography system demands more sensors to be settled. We plan to improve in reconstructed images by increasing the number of the electrodynamic sensors in tribo-electric tomography system. We investigate the influence of surface area to signal intensity solving the electrical field in the sensing zone using finite element method.     

Oxidative Degradation of Aqueous Cresols Induced by Gaseous Plasma with Contact Glow Discharge Electrolysis

The oxidative degradation of cresols smoothly proceeded toward inorganic end products when a gaseous plasma generated by means of dc glow discharge was sustained in contact with the surface of aqueous solution containing organic compounds. In order to get mechanistic insight, the monohydroxylation products from each isomeric cresol were closely examined as primary intermediates to reveal that the aromatic hydroxylation preferentially occurred at the position para to the hydroxyl group of each starting material. It was also established that the degradation of cresols strictly followed the first-order rate law. On the basis of the orientational analysis and the kinetical consideration including the effects of Fe ions added on the reaction rate, it was concluded that hydroxyl radical, which might result from the homolytic cleavage of water molecules by the action of plasma, was the most likely reagent responsible for the mineralization of cresols.     

Defluorination and Mineralization of Difluorophenols in Water by Anodic Contact Glow Discharge Electrolysis

Anodic contact glow discharge electrolysis (CGDE) is a DC-excited atmospheric pressure discharge, in which a steady non-thermal plasma is generated locally between the surface of an electrolytic solution and an anode in contact with it. The I–U characteristics of CGDE were investigated. The plasma temperatures were estimated to be in the range, 1373–2045 K. Hydroxyl radicals and hydrogen peroxide were the main oxidants generated by CGDE. The hydrogen peroxide concentration reached 31.2 mmol/L (mM) in a phosphate buffer solution without organic substrates. During CGDE, the DFPs and the corresponding total organic carbon (TOC) in water were consumed. Most of the fluorine atoms in the DFPs were converted to fluoride ions, and the fluoride concentration increased steadily. An analysis of the hydroxylation of DFPs suggested that the hydroxyl radicals generated by CGDE were the key species responsible for the degradation of DFPs, and the possible mechanistic routes of the mineralization of DFPs are proposed. The disappearance of DFPs and the TOC as well as the defluorination of the DFPs followed first-order kinetics. The rate of TOC disappearance was relatively constant: 1.00 ± 0.05 × 10^?2 min^?1. The order of disappearance of the DFPs was 2,6-DFP > 2,3-DFP > 2,5-DFP > 2,4-DFP > 3,4-DFP > 3,5-DFP. In contrast, the order of defluorination of the DFPs was 2,5-DFP > 2,3-DFP > 2,6-DFP > 2,4-DFP > 3,4-DFP > 3,5-DFP. Overall, the order of the reaction rates for each DFP was k_DFP > k_dF > k_TOC.     

Reversible haptotropic shift in zirconocene-hexapentaene complexes

Low-valent zirconocene species reacted with 1,1,6,6-tetraalkyl-1,2,3,4,5-hexapentaenes to form both 1-zirconacyclopent-3-ynes and eta2-pi-coordinated complexes according to the alkyl groups (R) and the existence of the neutral ligand (L). Haptotropic interconvertion between these two complexes was observed. It was proposed that double insertion of isocyanide into the Zr-C bond of 1-zirconacyclopent-3-ynes takes place via the isocyanide adduct of the eta2-pi-complex as an intermediate.     

Sodium D2 resonance radiation in single-pass sum-frequency generation with actively mode-locked Nd:YAG lasers

We report on a sodium D(2) resonance coherent light source achieved in single-pass sum-frequency generation in periodically poled MgO-doped stoichiometric lithium tantalate with actively mode-locked Nd:YAG lasers. Mode-locked pulses at 1064 and 1319 nm are synchronized with a time resolution of 37 ps with the phase adjustment of the radio frequencies fed to acousto-optic mode lockers. An output power of 4.6 W at 589.1586 nm is obtained, and beam quality near the diffraction limit is also achieved in a simple design.     

Electronic structures of vinylazide,vinylnitrene and 2H-azirine. Mechanism of the reaction from vinylazide to 2H-azirine

The mechanism of the conversion of vinylazides into 2H-azirines is examined by use of ab initio MO calculations. It is ascertained that vinylnitrenes have very weak bonds between the vinylazides and nitrogen molecule parts. It seems to decompose readily into the two fragments. This is one of the most characteristic features of vinylazides. The reaction is shown to proceed with N₂ at the tail of the vinylnitrene part. This mechanism accounts well for experimental results of the reaction.