Effect of an alkyl substituted in salen ligands on 1,4‐Cis selectivity and molecular weight control in the polymerization of 1,3‐butadiene with (salen)Co(II) complexes in combination with methylaluminoxane

The effect of an alkyl substituted in the aromatic ring of the salen ligand on the polymerization of butadiene (Bd) with (salen)Co(II) complexes in combination with methylaluminoxane (MAO) was investigated. The activity for the polymerization of Bd was influenced significantly by the introduction of alkyl groups at the 3,3′,5,5′‐positions in the aromatic ring of the salen ligand, and both the polymerization rate and 1,4‐cis contents increased in the following order with respect to the alkyl group: H < CH₃ < t‐C₄H₉. This is in good agreement with the bulkiness of the alkyl groups. The activity for the polymerization of the (salen)Co(II) complex possessing t‐C₄H₉ at the 3,3′‐positions was higher than that of the (salen)Co(II) bearing t‐C₄H₉ at the 5,5′‐positions. Thus, the introduction of bulky substituents at the 3,3′‐positions of the salen ligand was an important factor in achieving both high activity and high 1,4‐cis selectivity in the polymerization of Bd with (salen)Co(II) complexes in combination with MAO. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4088–4094, 2006     

Kinetics of OH radical reaction with phenanthrene: New absolute rate measurements and comparison with other PAHs

Using an in situ pulsed laser photolysis/pulsed laser‐induced fluorescence/technique, the OH reaction kinetics of a three‐ring polycyclic aromatic hydrocarbon (PAH), phenanthrene (and its deuterated form), was investigated over the temperature range of 373–1000 K. This study represents the first examination of the OH kinetics for phenanthrene at elevated temperatures using the absolute rate technique. The phenanthrene results indicate a temperature dependence similar to its isomer anthracene, reported previously in R. Ananthula, T. Yamada, and P. H. Taylor, J Phys Chem A 2006, 100, 3559–3566, over a similar temperature range. The phenanthrene rate constants are similar to anthracene at high temperature (ca. 1000 K) and a factor of ca. 2 lower at low temperatures (373–700 K). The rate measurements were best fitted by the following two‐parameter expression of the form ATⁿ: k₁(373–1000 K) = 4.98 ± 2.96 × 10^?6 * T^?1.97±0.10 (in units of cm³ molecule^?1 s^?1, error limits ±1σ). Rate measurements with deuterated phenanthrene below 725 K were indistinguishable from the phenanthrene rate measurements, within random error limits, providing strong evidence for an OH‐addition mechanism. The effects of PAH size on their reactivity with OH radicals based on selected data over the temperature range of 243–1200 K are discussed. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 629–637, 2007     

An integral transform whose kernel is a stream function of a steady Euler flow with axisymmetry

A new integral transform whose kernel is a Stokes stream function of an exact solution to the axisymmetric stationary Euler equations is derived with its inverse by using a Coulomb wave function. In the process of its derivation, a set of integral transforms with respect to the radial variable is also found. Each of them is different from the Hankel (the Fourier–Bessel) transform.     

Synthesis and characterization of a novel electroluminescent polymer based on a phenoxazine derivative

We report the preparation of a new electroluminescent polymer by the oxidative coupling copolymerization of N‐(4‐n‐butylphenyl)phenoxazine and 9,9‐di‐n‐butylfluorene with ferric(III) chloride. The reaction yields soluble polymers with a weight‐average molecular weight as high as 9000. The reactivity has been studied with respect to the reaction time, temperature, and feed ratio of the comonomers. Under optimum conditions, a copolymer with a 50% comonomer incorporation ratio can be obtained in a 75% yield. The polymers have been characterized with differential scanning calorimetry, cyclic voltammetry, and optical spectroscopy. A simple single‐layer light‐emitting‐diode device of an indium tin oxide/polymer/Mg–Ag structure shows a luminance of 200 cd/m² at an 18‐V operating voltage. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4338–4345, 2006     

Quantum group symmetry of partition functions of IRF models and its application to Jones' index theory

For each Boltzmann weight of a face model, we associate two quantum groups (face algebras) which describe the dependence of the partition function on boundary value condition. Using these, we give a proof of (non-)flatness of A-D-E connections of A. Ocneanu, which is a crucial algebraic part of the classification of subfactors with Jones' index less than 4.     

Generation of acidity of silica monolayer by network of SI-O-SI on alumina

Structures of materials deposited from various Si alkoxides on alumina were determined based on gravimetry, product analysis and coverage measurement. The activity for double-bond isomerization of l-butene was observed over the silica monolayer with a network of siloxanes (Si-O-Si) deposited from Si(OCH₃)₄ at 493 and 593 K. However, the isolated silica species deposited from Si(OCH₃)₄ at low temperatures (≤ 423 K) and those deposited from Si(OCH₃)_n(CH₃)_4-n (n ≥ 3) showed almost no activity. Based on these findings, the species — Al-O-SiOH in the network of Si-O-Si was suggested to be the Bronsted acid site.     

Influence of polyethylenimine on the precipitation process of lead sulfate crystals

Crystals of lead sulfate were precipitated in a solution of polyethylenimine (PEI) using a double-jet crystallizer. PEI controlled both the nucleation rate and the growth rate, and enabled to produce fine monodispersed crystals. This effect is considered to be due to a complexation between PEI and lead ion. The on-line measurement of the variation in the lead ion concentration indicated PEI lost its effect when a certain amount of reactants was supplied. And the duration in which PEI could control the precipitation rate and the amount of PEI had a strong correlation. In addition, it was suggested that their relationship could be utilized in order to produce monodispersed particles.     

Spectrophotometric assay of yeast vitality using 2,3,5,6-tetramethyl-1,4-benzoquinone and tetrazolium salts.

A method for the spectrophotometric assay of yeast vitality was developed using 2,3,5,6-tetramethyl-1,4-benzoquinone and tetrazolium salts. The metabolic efficiency of 2,3,5,6-tetramethyl-1,4-benzoquinone by yeast cells was used as an index of yeast vitality. 2,3,5,6-Tetramethyl-1,4-benzoquinone was reduced to 2,3,5,6-tetramethyl-1,4-hydroquinone by yeast cells. Then, the superoxide anion radicals generated from O2 by reduction with 2,3,5,6-tetramethyl-1,4-hydroquinone under alkaline conditions reduced tetrazolium salts to formazan, which exhibited absorbance maxima at 440 nm. A linear relationship between the absorbance and viable cell density was obtained in the range of 1.0 x 10(5)-2.0 x 10(7) cells/ml for a sample solution. During the cultivation of yeast cells, the absorbance showed almost an anti-parallel change with that of glucose in yeast growth and fermentation, suggesting that the absorbance change reflected the vitality of yeast cells.     

Dimerization of aldehydes to carboxylic esters catalyzed by K2[Fe(CO)4]–crown ether system

K₂[Fe(CO)₄] (1) with a crown ether was found to be an efficient catalyst for the dimerization of aldehydes to carboxylic esters. Several aromatic aldehydes including furfural gave the corresponding esters in good yields. This reaction also proceeded intramolecularly to give phthalide from phthalaldehyde. However, aliphatic aldehydes gave aldol-condensation products instead of the corresponding esters. In the reactions of p-substituted benzaldehydes with 1, the reactivity decreased with increase of the electron-releasing ability of the substituents. On the basis of these results, the reaction mechanism including the nucleophilic attack of tetracarbonylferrate dianion to the carbonyl carbon is discussed.