Ion-transfer voltammetry at a polarized room-temperature molten salt/water interface.

Tetraoctylammonium cation forms a room-temperature molten salt (RTMS) with 2,4,6-trinitrophenolate anion. The RTMS is immiscible with water (W) and forms a stable RTMS/W interface. It has been shown that the RTMS/W interface can be electrochemically polarized. A well-defined voltammetric wave due to the transfer of thiocyanate ion across the RTMS/W interface was observed within the potential window. This is the first example of a polarized RTMS/W interface.     

Rapid and sensitive determination of the conversion of UV-cured acrylic ester resins by pyrolysis-gas chromatography in the presence of an organic alkali.

The double-bond conversion of UV-cured resins prepared from pentaerythritol triacrylate (PETA) was determined by pyrolysis-gas chromatography in the presence of an organic alkali, tetramethylammonium hydroxide (TMAH). The pyrogram of the uncured prepolymer compound, consisting of PETA and a photoinitiator, 2,2-dimethoxy-2-phenylacetophenone, contained specific products reflecting the original acrylate structure, such as methyl acrylate (MA) and methyl ethers of pentaerithritol. Meanwhile, in pyrograms of the UV-cured PETA, the yields of MA considerably decreased. The double-bond conversions of the cured resins, irradiated with various UV dosages, were calculated based on the relative yields of MA among specific products in the pyrograms. The conversions determined by this approach were analyzed by comparing them with those estimated by Fourier-transform infrared spectroscopy.     

Polymorphy in the stereostructure of periodic polymer backbones

We theoretically investigated the polymorphy of the stereostructures of a periodic polymer. Using the polymer's internal conformation parameters of bond lengths, bond angles, and internal rotation angles, we extended the mathematical treatment for designing polymer backbones. We considered those periodic polymers whose unit cell consists of one (m = 1), two (m = 2), or three (m = 3) kinds of atoms. Moreover, for these three types of polymers, we supposed two catenation types for the skeleton atoms; one is a “homorotatory” sequence and the other is a “heterorotatory” one. To specify the backbone's stereostructure, we introduced several conformation parameters such as the helical pitch number n, the translation distance d, and the inclination angle of the skeleton plane Θ. By combining these parameters, we can systematically understand the variety and the possible polymorphy in the stereostructure of a periodic polymer backbone. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2829–2849, 2003     

Proximity Effects in Acid and Base-Catalysed Ether Formation

When heated with sodium ethoxide in ethanol 7-methylidenebicyclo[3.3.1]nonan-3-endo-ol (endo- 1 ) is converted into 1-methyl-2-oxa-adamantane ( 3 ). This reaction involves nucleophilic addition of a hydroxy group to an unactivated olefinic bond. Formation of the cyclic ether 3 also takes place when endo- 1 is heated in aqueous ethanol. This electrophilic addition is strongly catalysed by weak acids and suppressed by weak bases. These unusual reactions proceed more slowly with 7-methylbicyclo[3.3.1]non-6-en-3-endo-ol (endo- 2 ) and can be ascribed to a proximity effect. This follows from the IR . and NMR . spectra of endo- 1 and endo- 2 which show strong intramolecular hydrogen (OH-π) bonding. The unsaturated endo- and exo-alcohols 1 and 2 , respectively, undergo only exo-complexation with silver ion.     

Free-radical-induced polymerization of epoxides in the presence of maleic anhydride

The free-radical-induced reactions of cyclohexene oxide in the presence of maleic anhydride have been found to lead to polyether in presence of AIBN and to a mixture of polyether, ester, and maleic anhydride adduct of polyether with di-tert-butyl peroxide (DTBP), the amounts of the mixture components depending on the concentration of DTBP and the temperature. Analogous reactions in the presence of succinic anhydride lead to no polyether. The obtained polyether has no hydroxyl group. The reaction appears to consist of three different steps, radical initiation, cationic propagation, and radical termination.     

Distribution of the iron(III)-ethyl acetoacetate complex between aqueous solution and benzene

Summary Studies have been made on the distribution of iron(III)-ethyl acetoacetate complex between aqueous solution and benzene. Effect of pH, concentration of ethyl acetoacetate and shaking conditions were chosen as experimental parameters. Iron(III) can be well extracted from aqueous solution of pH 4.4–9.8 into benzene with constant extractability (97%), if the concentration of ethyl acetoacetate is kept in excess over that of iron(III). The applicability of the complex ( _max: 452 nm) to the spectrophotometric determination of iron is also discussed.

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Verteilung des Eisen(III)-Acetessigester-Komplexes zwischen wä\riger Lösung und Benzol

Zusammenfassung Zur Untersuchung der Verteilung wurden der pH-Wert, die Konzentration an Acetessigester und die Ausschüttelungsbedingungen variiert. Eisen(III) kann bei pH 4.4–9.8 mit Benzol mit einer konstanten Extrahierbarkeit von 97% ausgeschüttelt werden, wenn die Konzentration an Acetessigester größer ist als die an Eisen(III). Die Anwendbarkeit des Komplexes ( _max: 452 nm) zur spektralphotometrischen Eisenbestimmung wird diskutiert.

     

Observation of spatial distribution of laser-induced refractive index change in dye-doped liquid crystals

Spatial distributions of photothermal refractive index changes in dye-doped liquid crystals were determined by an optical interferometric method. The refractive index change of the order of 10^-1, including spatial distribution, was estimated by the described experimental technique. The absolute value of the refractive index change was proportional to the pump beam power, and the diameter of the index distribution was slightly larger than that of the pump laser beam due to heat conduction.     

Locating subsets of a normed space

Within the framework of Bishop's constructive mathematics, we give conditions under which a bounded convex subset of a uniformly smooth normed space over is located, extending results presented recently by F. Richman and H. Ishihara for subsets of a Hilbert space.