Radiation-Induced Solid-State Polymerization in Binary Systems. VI. Polymerization of Vinyl Compounds in the Supercooled Liquid Phase

Abstract

The radiation-induced polymerization of glass-forming systems containing vinyl monomers was investigated. Irradiation below the secondorder transition temperature (T_g) of the systems causes no in-source polymerization but does cause a very rapid postpolymerization in the course of heating above T_g. Differential thermal analysis was carried out to estimate T_g and to follow the postpolymerization.     

Photo- and electro-luminescent properties of thermotropic liquid crystalline quaterphenyl analogues comprising a 2,2'-bi-1,3,4-thiadiazole unit

Thermotropic liquid crystalline quaterphenyl analogues constituting a central 2,2'-bi-1,3,4- thiadiazole ring, the compounds 5,5'-bis(4-methoxy- and 4-octyloxy-phenyl)-1,3,4-thiadiazole, have been prepared and their photoluminescent (PL) and electroluminescent (EL) properties evaluated. The materials form enantiotropic smectic and nematic phases. The PL spectra showed that they emit blue and green fluorescence in the solid state. The octyloxy compound exhibited an EL spectrum with blue emission and is a candidate for organic EL applications.     

Polymerization of Styrene Initiated by Photoexcited Charge-Transfer Complex

Photopolymerization of styrene in the presence of pyromellitic dianhydride, an electron acceptor which forms a charge-transfer complex with the monomer, was studied. Polymerization was initiated by illumination with a light of wavelength longer than 350 nm, where only the charge-transfer absorption band exists. It was found that the reaction involves cationic and radical polymerizations and that the reaction course strongly depends on polarity of the system. It was also suggested by the dependence of the rate of polymerization on light intensity and temperature that the cationic polymerization consists of free ion and ion-pair polymerizations. These results were compared with those of the photoinduced cationic polymerization of α-methylstyrene, which has previously been studied.     

Radiation-Induced Polymerization of Urea Canal Complex. Part 3. Radiation-Induced Polymerization of Acrylonitrile-Urea Canal Complex in the Frozen State

Radiation-induced polymerization of acrylonitrile-urea canal complexes formed in frozen ethylene glycol or tert-butyl alcohol media was investigated. Formation of canal complexes in the frozen state was prolonged. The initial rate of polymerization was enhanced in the frozen state. The degree of polymerization of polymers obtained is found to show no depression at high conversions and is higher in the frozen state, suggesting stabilization of canal complexes by the frozen medium.     

Validation of an ultra‐performance liquid chromatography–tandem mass spectrometry method for the determination of flecainide in human plasma and its clinical application

A simple and reproducible bioanalytical method for the determination of flecainide in human plasma was developed and validated using an ultra‐performance liquid chromatography with tandem mass spectrometry (UPLC‐MS/MS) to obtain higher sensitivity than the current available methods. After simple protein precipitation, flecainide and a stable isotope‐labeled internal standard (IS) were chromatographed on an Acquity UPLC BEH C₁₈ column (2.1 × 100 mm, 1.7 µm) with isocratic elution of mobile phase consisting of 45% methanol containing 0.1% formic acid at a flow rate 0.25 mL/min. Detection was performed in positive electrospray ionization by monitoring the selected ion transitions at m/z 415.4/301.1 for flecainide and m/z 419.4/305.1 for the IS. The method was validated according to current bioanalytical method validation guidelines. The calibration standard curve was linear from 2.5 to 1000 ng/mL using 0.1 mL of plasma. No significant interferences were detected in blank human plasma. Accuracy and precision in the intra‐ and inter‐batch reproducibility study were within acceptance criteria. Neither hemolysis effects nor matrix effects were observed. The UPLC‐MS/MS method developed was successfully applied to determine plasma flecainide concentrations to support clinical studies and incurred sample reanalysis also ensured the reproducibility of the method. Copyright © 2015 John Wiley & Sons, Ltd.     

Stereoretentive N-Arylation of Amino Acid Esters with Cyclohexanones Utilizing a Continuous-Flow System

The N-arylation of chiral amino acid esters with minimal racemization is a challenging transformation because of the sensitivity of the α-stereocenter. A versatile synthetic method was developed to prepare N-arylated amino acid esters using cyclohexanones as aryl sources under continuous-flow conditions. The designed flow system, which consists of a coil reactor and a packed-bed reactor containing a Pd(OH)₂/C catalyst, efficiently afforded the desired N-arylated amino acids without significant racemization, accompanied by only small amounts of easily removable co-products (i. e., H₂O and alkanes). The efficiency and robustness of this method allowed for the continuous synthesis of the desired product in very high yield and enantiopurity with high space-time yield (74.1 g L⁻¹ h⁻¹) and turnover frequency (5.9 h⁻¹) for at least 3 days.