Effective synthesis of diiodinated picene and dibenzo[a,h]anthracene by AuCl-catalyzed double cyclization

6,13-Diiododibenzo[a,h]anthracene and 5,8-diiodopicene were synthesized by AuCl-catalyzed double cyclization. The highly selective reaction yielded a new class of peri-halogenated fused aromatics.     

A study on the role of gelatin in methacrylic-acid-based gel dosimeters

In radiotherapy treatment, polymer gel dosimetry can be used for verifying three-dimensional (3D) dose distributions. Gelatin is generally used as a gelling agent in the dosimeters. In this paper, another role of gelatin in a methacrylic-acid-based gel dosimeter (MAGAT) is investigated. Temperature increases due to exothermic polymerization in the irradiated gel are measured directly. Dose–R₂ responses are also obtained using MRI. It is shown that no appreciable increases in either temperature or R₂ are observed in MAGAT dosimeters made without gelatin, and that significant temperature and R₂ increases are observed when very low gelatin concentrations are used. These results indicate that gelatin is an important enabler for radiation-induced free-radical polymerization in methacrylic-acid-based gels. When gelatin is replaced by amino acids, changes in temperature are observed, along with small changes in R₂. The resulting dosimeter solutions remain transparent because the polymer does not precipitate as it does in regular MAGAT dosimeters containing gelatin. When the amino acids are replaced by acids without amino groups, no temperature or R₂ changes are observed, indicating that no polymer forms. These results show that amino groups (and possibly other functional groups) on the gelatin catalyze the radiation-induced free-radical polymerization that occurs in MAGAT dosimeters.     

Alkylative Carbocyclization of ω‐Iodoalkynyl Tosylates with Alkynyllithium Compounds Through a Carbenoid‐Chain Process Leading to (1‐Iodoprop‐2‐ynylidene)tetrahydrofurans and ‐cyclopropanes

Alkylative carbocyclization reactions of ω‐iodoalkynyl tosylates with alkynyllithium compounds to give products with incorporated iodine atoms are described. Slow addition of 2‐(3‐iodoprop‐2‐ynyloxy)ethyl tosylates to 1‐alkynyllithium compounds in tetrahydrofuran at 40 °C followed by additional stirring at this temperature gives (Z)‐3‐(1‐iodoprop‐2‐ynylidene)tetrahydrofurans stereoselectively in good to moderate yields. Under similar conditions at 0 °C, 4‐iodobut‐1‐ynyl tosylates react with 1‐alkynyllithium compounds to give (1‐iodoprop‐2‐ynylidene)cyclopropanes. The carbocyclization reactions are proposed to proceed through a new carbenoid‐chain process involving the exo cyclization of a lithium acetylide intermediate and the vinylic substitution of the resulting TsO,Li‐cycloalkylidenecarbenoids (Ts=tosyl) by 1‐alkynyllithium compounds.     

Multiscale Lagrangian fluid dynamics simulation for polymeric fluid

We have developed a simulation technique of multiscale Lagrangian fluid dynamics to tackle hierarchical problems relating to historical dependency of polymeric fluid. We investigate flow dynamics of dilute polymeric fluid by using the multiscale simulation approach incorporating Lagrangian particle fluid dynamics technique (the modified smoothed particle hydrodynamics) with stochastic coarse‐grained polymer simulators (the dumbbell model). We have confirmed that our approach is well in agreement with the macroscopic results obtained by a constitutive equation corresponding to the dumbbell model, and observed that microscopic thermal fluctuation appears in macroscopic fluid dynamics as dispersion phenomena. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 886–893, 2010     

9,9′‐spirobifluorene‐containing polycarbonates: Transparent polymers with high refractive index and low birefringence

Syntheses of 2,2′‐bisalcoholic group‐substituted 9,9′‐spirobifluorene monomers 2 were performed by the reaction of 2,2′‐dihydroxy‐9,9′‐spirobifluorene 2a with haloalcohols. Polycarbonates consisting of 9,9′‐spirobifluorene skeleton in the main chain (PC 4 ) were synthesized by the polycondensation of 2,2′‐bisalcoholic monomers 2 and triphosgene or diphenyl carbonate. PC 4 showed good thermal stability: the 5% weight loss temperature was over 330 °C under both nitrogen and air atmospheres. The glass transition temperature was in a range of 16–269 °C estimated by differential scanning calorimetry, depending on the flexibility of the alkylene or oxyethylene chains of 2 . PC 4 showed high solubility toward ordinary organic solvents such as CHCl₃, benzene, and THF, making possible the preparation of the flexible thin films. Very high refractive index in a range of 1.62–1.66 at 589 nm was observed although PC 4 consists only of C, H, and O atoms, whereas very low degree of birefringence was confirmed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3658–3667, 2010     

Oxygen‐sensing properties of 5,10,15,20‐tetraphenylporphinato platinum(II) and palladium(II) covalently bound on poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate)

A novel methacrylate monomer bearing 5,10,15,20‐tetraphenylporphyrinato palladium(II) (PdTPP) (monomer 1a ) was synthesized and copolymerized with isobutyl methacrylate (IBM) and 2,2,2‐trifluoroethyl methacrylate (TFEM) to give poly (IBM‐co‐TFEM) bearing PdTPP (copolymer 2a ) as a dye‐conjugated oxygen‐permeable polymer for pressure‐sensitive paint applications. The introduction of PdTPP into copolymer 2a was confirmed by UV–vis spectroscopy and extended X‐ray absorption fine structure analysis. The Stern–Volmer plots of the copolymer 2a and a mixture of PdTPP and poly(IBM‐co‐TFEM) both showed downward curvature, unlike that of the platinum complex analogue (copolymer 2b ) previously reported. The plots were successfully fitted with a two‐site model to give two distinct Stern–Volmer constants (K_SV1 and K_SV2) and the partition ratio f₁. Interestingly, the f₁ values for the copolymer 2a were almost constant at about 0.98, whereas those of the mixture of PdTPP and poly(IBM‐co‐TFEM) increased from 0.889 to 0.967 as the temperature was increased. This finding suggests that there are two distinct microheterogeneities, one temperature‐dependent and the other temperature‐independent, in the mixture of PdTPP and poly(IBM‐co‐TFEM). The dye‐conjugation approach effectively eliminates the temperature‐dependent, but not the temperature‐independent microheterogeneity. The luminescence decays of copolymers 2a and 2b and the corresponding mixtures in the absence of oxygen indicated that the temperature‐dependent microheterogeneity involves an oxygen diffusion process, whereas the temperature‐independent one appears to be inherent nature in PdTPP. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 663–670, 2010     

Analytical aspects of cyanobacterial volatile organic compounds for investigation of their production behavior

In order to fully understand the role of volatile organic compounds (VOCs) under natural conditions, an adaptable analytical method was developed as the first step. β-Ionone, β-cyclocitral, 2-methyl-1-butanol and 3-methyl-1-butanol were simultaneously analyzed in addition to geosmin and 2-MIB using GC/MS with SPME. The slight modification of a known method allowed the simultaneous detection and quantification of these VOCs. The SIM of the 3-methyl-1-butanol was always accompanied by a shoulder peak, suggesting the presence of two compounds. In order to separate both compounds, the GC/MS conditions were optimized, and the additional peak was identified as 2-methyl-1-butanol by direct comparison of the authentic compound, indicating that the Microcystis strain always produces a mixture of 2-methyl-1-butanol and 3-methyl-1-butanol. Furthermore, it was found that 2-methyl-1-butanol and 3-methyl-1-butanol were predominant in the dissolved fractions. β-Cyclocitral was easily oxidized to provide the oxidation product, 2,6,6-trimethylcyclohexene-1-carboxylic acid, which causes the blue color formation of cyanobacteria as a consequence of acid stress. The intact acid could be satisfactorily analyzed using the usual GC/MS without derivatization.     

The reaction of OH with acetaldehyde and deuterated acetaldehyde: Further insight into the reaction mechanism at both low and elevated temperatures

The pulsed laser photolysis/laser‐induced fluorescence technique has been used to conduct additional measurements of the gas‐phase CH₃CHO + OH reaction. These measurements were conducted to verify the complex temperature dependence previously observed by the authors and to acquire mechanistic information about the reaction mechanism in the form of primary kinetic isotope effects. Primary kinetic isotope effect measurements at temperatures of 297, 383, 600, and 860 K indicate that H abstraction from the acetyl group dominates that of the methyl group at low to modest temperatures (?600 K) and H abstraction from the methyl group dominates that from the acetyl group at higher temperatures (860 K). A bi‐exponential © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 489–495, 2006