Reaction of diphenyldiacetylene by annealing under elevated pressure

Reaction of diphenyldiacetylene (1,4-diphenylbutadiyne) by annealing under elevated pressure (0.1–500 MPa) was carried out. Diphenyldiacetylene reacted at 210°C with appearance of gas, and this temperature was independent of the pressure. The measurement of high pressure differential thermal analysis (DTA) revealed that the reaction temperature under elevated pressure was below 24–42°C of the exothermic peak temperature. This implied that exothermic reaction occurred under elevated pressure. Elementary analysis, gel permeation chromatography (GPC), FTIR, Raman scattering, and high resolution ¹³CNMR experiments were performed to characterize the structure of the product. It was indicated that the product was a mixture of derivative of condensed polycyclic aromatic compound with phenyl group and diphenyldiacetylene oligomer. The fraction of the derivatives increased with increasing pressure, and pressure accelerated the dehydrogenation of the derivatives. The number-averaged molecular weight (M_n) of the diphenyldiacetylene oligomer was 470–610 and the weight-averaged molecular weight (M_w) was 1700–2300. It was considered that the oligomer had a polyacene-based structure. © 1994 John Wiley & Sons, Inc.     

Versatile dehydrogenative alcohol silylation catalyzed by Cu(I)-phosphine complex

[reaction: see text] Cu(I) complexes of xanthane-based diphosphines were versatile catalysts for dehydrogenative alcohol silylation, exhibiting high activity and broad substrate scope. Highly selective silylation of 1-decanol over 2-decanol is possible even with a silylating reagent of small steric demand such as HSiMe(2)Ph or HSiEt(3).     

The Catalysis of Vapor-Phase Beckmann Rearrangement for the Production of ε-Caprolactam

Recently, Sumitomo Chemical Co., Ltd. developed the vapor-phase Beckmann rearrangement process for the production of -caprolactam. In the process, cyclohexanone oxime is rearranged into -caprolactam using a zeolite as a catalyst instead of sulfuric acid. EniChem in Italy developed the ammoximation process that involves the direct production of cyclohexanone oxime without producing any ammonium sulfate. Sumitomo Chemical Co., Ltd. has commercialized the combined process of vapor-phase Beckmann rearrangement and ammoximation in 2003.In this paper, the authors focus on some aspects of the vapor-phase Beckmann rearrangement catalysis. A solid catalyst that is mainly composed of a high-silica MFI zeolite (Silicalite-1) has been developed for the vapor-phase Beckmann rearrangement. This catalyst does not possess acidity that can be detected by ammonia TPD. Methanol fed into the reactor with cyclohexanone oxime improves the yield of caprolactam. Methanol reacts with terminal silanols on the zeolite surface and converts them to methoxyl groups. The modification of the catalyst by methanol has an important role for the Beckmann rearrangement reaction.Nest silanols located just inside the pore mouth of the MFI zeolite are supposed to be the active sites of the catalyst. We propose that the coordination between the NOH group of cyclohexanone oxime molecule and the nest silanols through hydrogen bonding is responsible for the reaction. The reaction mechanism of Beckmann rearrangement under vapor-phase conditions is the same as in the liquid phase, namely, the alkyl group in anti-position against the hydroxyl group of the oxime migrates to the nitrogen atom's position.     

Conformational dynamics of phototropin 2 LOV2 domain with the linker upon photoexcitation

Conformational dynamics of LOV2 domain of phototropin, a plant blue light photoreceptor, is studied by the pulsed laser induced transient grating (TG) technique. The TG signal of LOV2 without the linker part to the kinase domain exhibits the thermal grating signal due to the heat releasing from the excited state and a weak population grating by the adduct formation. The diffusion coefficients of the adduct product after forming the chemical bond between the chromophore and Cys residue are found to be slightly smaller than that of the reactant, which implies that the core shrinks slightly on the adduct formation. After that change, no significant conformational change was observed. On the other hand, the signal of LOV2 with the linker part to the kinase domain clearly shows very different diffusion coefficients between the original and the adduct species. The large difference indicates significant global conformational change of the protein moiety upon the adduct formation. More interestingly, the diffusion coefficient is found to be time-dependent in the observation time range. The dynamics representing the global conformational change is a clear indication of a spectral silent intermediate between the excited triplet state and the signaling product. From the temporal profile analysis of the signal, the rate of the conformational change is determined to be 2 ms.     

Radiative and non-radiative decay processes of the excited state of the colored form of photochromic furylfulgide

The time evolution of the luminescence of the colored form of a furylfulgide dispersed at various concentrations in a poly(methyl methacrylate) film was measured as a function of the luminescence photon energy. The observed decay time of the luminescence is about 1–2 ns and one order of magnitude shorter than the radiative lifetime (14 ns) estimated from the absorption intensity. The decay time is independent of temperature below 77 K. These results suggest that the non-radiative tunneling process from the excited state to the ground state is responsible for the decay.     

Synthesis of hipposudoric and norhipposudoric acids: the pigments responsible for the color reaction of the red sweat of Hippopotamus amphibius

Highly unstable pigments, hipposudoric acid and norhipposudoric acid, isolated from the red sweat of hippopotamus were synthesized using the Pschorr reaction for the construction of the fluorene nucleus as the key step and the careful oxidation in the last step.     

Synthesis of a useful lauryl thioglycoside of sialic acid and its application

An efficient synthesis of a useful thioglycosyl donor 2 was accomplished directly from known peracetylated sialic acid methyl ester and 1-dodecanethiol (lauryl mercaptan) in the presence of BF₃-OEt₂. The reactivities of the lauryl glycosides for glycosidation by means of TMSOTf as a convenient promoter were investigated, and the lauryl thioglycoside showed satisfactory activities. Further transformation of the lauryl glycoside was also attempted to give a 5-azide analogue 14 of the sialic acid, which was also reacted with a secondary alcohol in the presence of TMSOTf to give known glycoside 15 in high yield.     

Immunoanalyser for Candida albicans based on the human olfactory function

A novel immunoanalyser system based on the human olfactory function has been developed and successfully applied to immunoassay for Candida albicans. After the immunoreaction of C. albicans and its antibody (IgG), the reaction solution was added gently to a phosphate buffer solution in a conical reaction vessel. The buffer in this vessel was previously saturated with Versalide (1,1,4,4-tetramethyl-6-ethyl-7-acetyl-l,2,3,4-tetrahydronaphthalene) as an odour marker and its odour was sensed by the nose of a tester immediately above the vessel. The addition of a sufficient amount of the reaction solution caused the disappearance of the odour. As the buffer level was raised and the surface area increased, the odour appeared again. A relationship was obtained between the change in buffer level until the odour reappeared and the concentration of C. albicans in the reaction solution. Based on this principle, C. albicans could be determined in the range 10²– 10⁵ cells ml^?1.     

A process in need is a process indeed: scalable enantioselective synthesis of chiral compounds for the pharmaceutical industry

This report deals with enantioselective synthesis of viracept 1 (nelfinavir mesylate, AG 1343), a potent HIV protease inhibitor, and 3-hydroxytetradecanoic acid 3, a component of lipid A comprising lipopolysaccharide embedded in the cell surface of Gram-negative bacteria, from both strategic and practical perspectives. As regards the synthesis of 1, the synthetic approaches to its central intermediate 2 possessing the common structural motif of 1,4-differentially substituted-2-amino-3-hydroxylbutane are mainly discussed with emphasis on the molecular symmetry that has helped streamline the synthetic strategy. In the discussion of the synthetic strategies to access a single enantiomer of 3, the chiral methodologies that have been applied so far are assessed for industrial viability; the synthetic alternatives explored include resolution via diastereomeric salt formation, lipase-catalyzed kinetic resolution, asymmetric synthesis, and chiral pool approaches.     

Novel synthesis of polymer and carbonaceous nanomaterials via a micelle/silicate nanostructured precursor

Mesoporous carbonaceous materials with relatively high surface area have been synthesized by a new method composed of in situ polymerization of divinylbenzene in the hydrophobic phase of a hexagonally arrayed micelle/silicate nanocomposite and subsequent carbonization and hydrofluoric acid treatments, while rod-like carbons were obtained from a direct incorporation of divinylbenzene into the mesopores of MCM-41.