The process of 4‐hydroxybiphenyl synthesis from 4‐isopropylbiphenyl

The kinetics of the oxidation of 4‐isopropylbiphenyl ( 1 ) in the liquid phase by oxygen to 1‐(1,1′‐biphenyl‐4‐yl)‐1‐methylethyl hydroperoxide ( 2 ) was investigated. The oxidizability of 1 in the temperature range from 60°C to 120°C and the overall energy activation of oxidation were determined. Long‐term oxidation of 1 to 2 in the temperature range of 80–120°C was investigated, and the yield and selectivity of the process were determined. Pure 2 was obtained, and its properties were defined. 4‐Hydroxybiphenyl was obtained as a result of the acidic decomposition of 2 . © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 527–532, 2008     

Evaluation of the inelastic mean free path (IMFP) of electrons in polyaniline and polyacetylene samples obtained from elastic peak electron spectroscopy (EPES)

The inelastic mean free path (IMFP) of electrons was determined experimentally for selected polyaniline and polyacetylene samples with Ag and Ni references using elastic peak electron spectroscopy (EPES). The surface composition was determined by XPS and density by helium pycnometry. The high resolution hemispherical ESA-31 and ADES-400 spectrometers were used for measurements in the energy range E = 0.5–3.0 keV and E =0.4 − 1.6 keV, respectively. The integrated elastic peak intensity ratios for sample and reference were calculated using the Monte Carlo (MC) algorithm based on the electron elastic scattering cross-sections database NIST SRD64 version 3.1 and applying TPP-2M IMFPs for polymers. Surface excitation parameters (SEP) and material parameters ( _ach ) for polymers were determined, using the model of Chen, from comparison of measured and MC calculated elastic peak intensity ratios. These corrections proved to be efficient in decreasing the percentage deviations between the obtained IMFPs and the TPP-2M formula IMFPs. The elastic peak of hydrogen was observed in the EPES spectra of polymers. The experimental contribution of the hydrogen to the total elastic peak was 0.58%, while this value obtained from the MC simulations was 1.98%.      

On residualities in the set of Markov operators on

We show that the set of those Markov operators on the Schatten class such that , where is one-dimensional projection, is norm open and dense. If we require that the limit projections must be on strictly positive states, then such operators form a norm dense . Surprisingly, for the strong operator topology operators the situation is quite the opposite.

     

Crystal Structures of Methyl (Methyl 3-azido-2,3-dideoxy-β-L-lyxo- and -β-D-arabino-hexopyranosid)uronates

Single-crystal x-ray diffraction data for methyl (methyl 3-azido-2,3-dideoxy-β-L-lyxo- and β-D-arabino-hexopyranosid)uronates are presented. Three independent molecules in the asymmetric part of the unit cell of the β-D-arabino stereoisomer were found. These differ slightly in the geometry of the groups bound to the pyranose rings. Conformations and the geometry parameters of all the molecules as well as the planarity of the carbomethoxy group, the linearity of the azido group, and the orientation of the aglycone in the crystal lattice are discussed. Influence of the hybridization, resonance, and crystal packing on the geometry parameters is shown.     

Novel Copolymers of Vinyl Acetate and Some Ring‐Substituted 2‐Phenyl‐1,1‐dicyanoethylenes

Electrophilic trisubstituted ethylene monomers, some ring‐substituted 2‐phenyl‐1,1‐dicyanoethylenes, RC₆H₄CH?C(CN)₂ (where R is 3‐Br, 4‐CH₃O; 5‐Br, 2‐CH₃O; 4‐Cl, 3‐NO₂; 5‐Cl, 2‐NO₂; 2‐CN, 3‐CN, 4‐CN, and 4‐(CH₃)₂N), were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and vinyl acetate were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C‐NMR, GPC, DSC, and TGA. High T _g of the copolymers, in comparison with that of polyvinyl acetate, indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 190–800°C range.     

β-( N -Acylamino)vinylphosphonium Salts--Synthesis and Properties

A reaction of g -carbonyl phosphorus ylides with imidoyl halides gives hitherto unknown g -( N -acylamino)vinylphosphonium salts. The same product can be obtained using the N-monosubtituted amide/Ph 3 PBr 2 /Et 3 N system instead of imidoyl halide. The key step of the reaction probably involves an intramolecular [1,3] O-to-N migration of the vinyl group, converting the primary O -imidoylation product into g -( N -acylamino)vinylphosphonium salt.     

Indirect Speciation Analysis of Thallium in Plant Extracts by Anodic Stripping Voltammetry

A sensitive voltammetric method (DPASV) was developed for the determination of Tl(I) and Tl(III) in plant extracts. To limit the influence of the organic matrix on the measurements, UV irradiation and addition of Amberlite XAD‐7 resin was studied. The application of 0.5 g of the resin allowed defining thallium speciation in 10.0 mL of a solution containing 0.20 mL of Sinapis alba extract. The quantification limit of 0.5 ng mL^?1 Tl(I) was found for only 10 min of preconcentration, and is low enough to allow dilution of the sample before thallium determination. The procedure was validated using the recovery study and intermethod comparison with HPLC ICP MS.