A novel ring transformation of uracil into the benzene ring system

Reaction of 5-formyl-1,3-dimethyluracil with some active methylene compounds in the presence of base causes novel ring transformations to give the p-hydroxybenzoates and the nicotinate.     

A new selective population transfer experiment using a double pulsed field gradient spin-echo

A new pulse sequence is proposed for the determination of scalar coupling correlation in small- and medium-sized organic compounds. The method uses a combination of the double pulsed field gradient spin-echo (DPFGSE) and the selective population transfer (SPT) techniques and is shown to be useful in the analysis of complex spectra with many overlapped signals. The usefulness of this method in the structural elucidation of natural substances is demonstrated using strychnine and digitoxin as examples.     

A versatile method for preparation of O-alkylperoxycarbonic acids: epoxidation with alkyloxycarbonylimidazoles and hydrogen peroxide

A variety of O-alkylperoxycarbonic acids ($\text{2}$) were conveniently prepared $\text{in}$$\text{situ}$ by utilizing alkyloxycarbonylimidazoles ($\text{1}$) as their precursors. Epoxidation of alkenes with such peroxy-acids was studied and their reactivities were compared with those of peroxycarboxylic acids.     

Effects of metal salts on polymerization. Part VII. Radical polymerization and spectra of vinylpyridine in the presence of cobaltous chloride

The radical polymerizability of vinylpyridines in the presence of cobaltous chloride was studied in DMF solution, and the results were correlated with the spectroscopic data obtained for methanol solution. In general, the behavior of vinylpyridine complexed with cobaltous chloride is qualitatively the same as that of zinc complexes reported previously. The rates of polymerization were enhanced by the addition of cobaltous chloride when 4-vinylpyridine(4-VP) or 2-methyl-5-vinylpyridine(MVP) was the monomer, whereas the polymerization of 2-vinylpyridine(2-VP) was retarded by cobaltous chloride. The monomer reactivity of all the vinylpyridines was also enhanced by complex formation as studied by copolymerization with styrene. The enhancement of reactivity of 4-VP complexed with cobaltous chloride is somewhat smaller than that of the corresponding zinc complex.     

Molecular mobility of lyophilized poly(vinylpyrrolidone) and methylcellulose as determined by the laboratory and rotating frame spin-lattice relaxation times of 1H and 13C

Laboratory- and rotating- frame spin-lattice relaxation times (T(1) and T(1rho)) of (1)H and (13)C in lyophilized poly(vinylpyrrolidone) (PVP) and methylcellulose (MC) are determined to examine feasibility of using T(1) and T(1rho) as a measure of molecular motions on large time scales related to the storage stability of lyophilized formulations. The T(1rho) of proton and carbon was found to reflect the mobility of PVP and MC backbones, indicating that it is useful as a measure of large-time-scale molecular motions. In contrast to the T(1rho), the T(1) of proton measured in the same temperature range reflected the mobility of PVP and MC side chains. The T(1) of proton may be useful as a measure of local molecular motions on a smaller-time-scale, although the measurement is interfered by moisture under some conditions. The temperature dependence of T(1) and T(1rho) indicated that methylene in the MC molecule had much higher mobility than that in the dextran molecule, also indicated that methylene in the PVP side chain had a higher mobility than that in the MC side chain.     

Optical microscopy and in situ Raman scattering of single crystalline ethylene hydrate and binary methane-ethylene hydrate at high pressures

Visual observations through a microscope and in situ Raman measurements have been made for single crystalline ethylene hydrate (EH) and binary methane-ethylene hydrate (MEH) at pressures up to 3.7 GPa and room temperature. Both hydrates showed pressure-induced phase transitions at 1.6, 2.0, and 3.0 GPa for EH and at 1.7, 2.1, and 3.3 GPa for MEH. The cubic sI phase of EH and MEH remains stable up to 1.6 and 1.7 GPa, respectively, which are more widely ranging values than the values for the methane hydrate sI phase. In this sI phase of binary MEH, the cage occupancies by methane and ethylene molecules are investigated from Raman spectra. Above P = 3.0 GPa for EH and 3.3 GPa for MEH, they decomposed by associating with the formation of the polyethylene.     

High n-value phases in the complex bismuth oxides with layered structure,Bi2CaNan−2NbnO3n+3

Complex bismuth oxides with layered structure are prepared with a series of compositions in the system Bi₂CaNb₂O₉-NaNbO₃. It is found by X-ray powder diffraction that each compound is composed of more than two phases, which are described by a formula Bi₂CaNa_n?2Nb_nO_3n+3, e.g., in the sample with the nominal composition Bi₂CaNb₂O₉ · 8NaNbO₃, the phases with n = 6 to 8 appear predominantly. These phases are closely intergrown to each other. Moreover, high-resolution electron microscopy reveals that microsyntactic intergrowth frequently occurs in the phases with n > 5. The occurrence of the latter intergrowth is explained in terms of the bond length obtained.     

Single-bubble sonochemiluminescence in aqueous luminol solutions

Sonochemiluminescence (SCL) of luminol due to a single bubble is studied through spectral measurement. No SCL was observed from a stable single bubble that emitted high-intensity sonoluminescence (SL). In contrast, SCL was observed under conditions of an unstable dancing bubble, where a bubble grows and ejects tiny bubbles, making it "dance" by counteraction. Furthermore, SCL was observed from dancing bubbles even when SL was not observed, depending on the dissolved gas content. The instability of bubble collapse is the key parameter governing SCL.     

Cyclic esters of aliphatic diacids with pyrocatechol and hydroquinone

Cyclic esters of adipic acid, suberic acid and sebacic acid were prepared by reaction of the acid dichlorides and pyrocatechol or hydroquinone in benzene under high dilution conditions. While only the cyclic dimers could be obtained from hydroquinone, pyrocatechol formed cyclic monomers as well as cyclic dimers (and also a cyclic dimer with succinic acid). The structure of all compounds was confirmed by¹H-NMR- and mass spectra. The crystal structures of the pyrocatechol esters were determined by single crystal X-ray analysis.

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Cyclische Ester aliphatischer Dicarbonsäuren mit Brenzcatechin und Hydrochinon

Zusammenfassung Es wurden cyclische Ester von Adipinsäure, Korksäure und Sebacinsäure durch Reaktion der entsprechenden Säure-Dichloride mit Brenzcatechin oder Hydrochinon bei hoher Verdünnung hergestellt. Während mit Hydrochinon lediglich die cyclischen Dimeren erhalten werden konnten, wurden mit Brenzcatechin sowohl cyclische Monomere als auch cyclische Dimere erhalten (ebenfalls das cyclische Dimer mit Bernsteinsäure). Die Strukturen wurden mittels¹H-NMR und Massenspektren gesichert. Die Kristallstrukturen der Brenzcatechin-Ester wurden mittels Röntgenstrukturanalyse bestimmt.

     

Crossed molecular beam chemiluminescence study of the metastable mercury reaction: Hg(3P)+Br2 → HgBr(B) + Br

Chemiluminescence from HgBr(B) formed in the reaction of Hg(6³P_o with Br₂ has been observed using a N₂-seeded nozzle beam of metastable Hg³P_o) atoms. The cross section has been estimated to be 3⁺³_?2 at a collission energy of 0.33 eV. This value is smaller by more than an order of magnitude than the corresponding value for Hg(³P₂) atoms measured by Krause et al., in accordance with their inference based on less direct evidence.