Analytical applications of copper(II) and copper(I) in acetonitrile: potentiometric and spectrophotometric determination of dithiocarbamates

The use of copper(II) perchlorate and tetra-acetonitrilocopper(I) perchlorate (in acetonitrile) for the potentiometric and spectrophotometric determination of dithiocarbamates in acetonitrile medium is described. The proposed methods are simple, accurate and reliable and show promise of wide applicability. They are recommended for routine determination of dithiocarbamates. Their advantages over the carbon disulphide evolution method, commonly employed for the determination of these compounds, are discussed.     

Nuclear quadrupole interaction at133Cs in some barium compounds

Nuclear quadrupole interaction frequencies at¹³³Cs following the electron-capture decay of¹³³Ba for BaSO₄, Ba/BrO₃/2 and Ba/NO₃/2 were obtained by measuring the perturbation of 356–81 keV cascade of¹³³Ba. Nuclear quadrupole interaction frequencies for BaSO₄ and Ba/BrO₃/2 are 17.2 Mrad sec^–1 and 14.6 Mrad sec^–1, respectively, while no perturbation of 356–81 keV cascade was observed in case of Ba/NO₃/2. Further the possibility of any after-effects of electron-capture decay is ruled out through the measurement of 276–161 keV gamma-gamma directional correlation.     

A new approach to all—cis triquinane synthesis and a new route to the C16—hexaquinane system

A new synthesis of all-cis triquinanes is presented. The examples bear a cis substituent on the fifth position of the central ring, and are thus all-cis pentasubstituted cyclopentanes. The stereo-controlled addition of organometallics of 7-ketonorbornenes is considered, as is “reductive solvolysis” of such adducts to the corresponding hydrocarbons. The preparation of trans-3,4-dimethoxycyclopentyl chloride is given, as is that of the corresponding organolithium. The use of quinoxaline derivatives in aldol-type reactions is considered, with examples. A new approach to the C₁₆-hexaquinane system is developed. The ring systems reported include: tricyclo-[8.2.1.0^2,9]tridecane, tricyclo[6.3.0.0^3,7]undecane, tetracyclo-[10.1.0.0^2,9.0^10,13]tridecane, pentacyclo[8.5.1.0^2,6.0^7,16.0^11,15]hexadene and hexacyclo(8.5.1.0^2,6.0^3,14.0^7,16.0^11,15]hexadecane.     

Determination of thiuram disulphides and analysis of thiuram disulphide-dithiocarbamate mixtures

Potassium trithiocarbonate is used as reluctant for the titrimetric determination of thiuram disulphides in dimethylformamide-water media. The method is based on reductive cleavage of the disulphide linkage to yield the corresponding dithiocarbamates. In visual titrations, the end-point is marked by appearance of a yellow colour with the first drop of reagent added in excess. The method is simple, accurate, reliable and of wide applicability. It has been successfully extended to the analysis, in the same sample solution, of thiuram disulphide-dithiocarbamate mixtures.     

Role of phenoxy radicals in PCDD/F formation

In this work, the role of phenoxy radicals in polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzofurans (PCDD/F) formation was investigated by studying the slow oxidation of 2‐chlorophenol (2‐CP) and 2‐chloroanisole (2‐CA) at a gas‐phase concentration of 4 ppm (～2.1 × 10⁴ μg/m³) over a temperature range of 400–800°C. Residence times were maintained at 2.0 ± 0.10 s. PCDD/F reaction products were dibenzofuran, dibenzo‐p‐dioxin, 4‐chlorodibenzofuran, 1‐chlorodibenzo‐p‐dioxin, 4,6‐dichlorodibenzofuran, and 1,6‐dichlorodibenzo‐p‐dioxin (1,6‐DCDD). Major products observed in these experiments were 2,6‐dichlorophenol, 3‐phenyl‐2‐propenal, 1‐indanone, 1,3‐isobenzofurandione, and 3‐phenyl‐2‐propenoyl chloride. The 2‐CP and 2‐CA experiments, along with the variable concentration 2‐CA experiments, showed that the concentration of radicals present in the oxidation system has a significant effect on the PCDD/F product distribution and ultimately the PCDD/PCDF ratio. Also, the observation of dichlorinated phenoxy phenol and dichlorinated dihydroxybiphenyl, the proposed intermediate species in the radical–radical mechanism, suggests that radical–radical mechanism dominates gas‐phase PCDD/F formation. This information will be helpful in constructing a detailed kinetic mechanism of PCDD/F formation/destruction in combustor postcombustion zone. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 531–541, 2002     

The first example of a crystalline guest-free form of the tris(5-acetyl-3-thienyl)methane (TATM) host material

The first example of a guest-free crystalline form of tris(5-acetyl-3-thienyl)methane (TATM), in both powder and single crystal form, was obtained by leaching water-soluble guests out of the guest-host inclusion compounds with acetone, ethanol and methanol.     

Uranyl ion luminescence quenching with benzene derivatives and related compounds. Linear free energy relationship

Irradiation of uranyl ion with light of wavelength =345 nm to singlet state, through vibrational relaxation populates the lowest excited triplet state from where it emits luminescence emission at 486, 506, 535 nm. Elongation and weakening of uranium-oxygen multiple bonds is evident from the lower stretching frequency (701.15 cm^–1) in the excited state relative to the ground state (942.5 cm^–1). Series of aromatic molecules including benzene derivatives, aromatic hydrocarbons and heterocyclic molecules very efficiently quench uranyl ion luminescence through nonradiative donor-acceptor complex formation. Increasing inductive effect, resonance phenomena and extension of aromatic -electron cloud determine the order of Stern-Volmer constant to measure their quenching action.     

Parity of the band head at 3710 keV in 99Rh using clover detector as compton polarimeter

Clover detector has been used as a Compton polarimeter to measure the linear polarization of γ-rays produced in heavy ion fusion reaction. The polarization sensitivity of the clover detector has been measured over γ-ray energies ranging from 386 to 1368 ke V. The E1 multipolarity of the 1117 keV transition in ⁹⁹Rh has been established using this polarimeter. This has resulted in the assignment of negative parity to the band head at 3710 keV in ⁹⁹Rh.