Effects of vinyl series polymers on the formation of hematite particles in a forced hydrolysis reaction

The influence of polymers on the formation of hematite particles from forced hydrolysis of acidic FeCl(3) solution was investigated using vinyl series polymers with different functional groups. The disk-like hematite particles were produced from forced hydrolysis of acidic FeCl(3) solution in the presence of polyvinyl alcohol (PVA: 0-1 wt%). On the other hand, spherical particles were produced by addition of very small amounts of polyacrylamide (PAAm: 0-0.004 wt%). The size of spherical particles was slightly decreased with increase in the concentration of PAAm. The ellipsoidal particles were precipitated by addition of a very low concentration of polyacrylic acid (PAAc: 0-0.004 wt%). The effect of polymers on the hematite particle formation was expressed in the order of PVA相似文献   

Indium-catalyzed reduction of allyl bromide with gallium or aluminum. Formation of allylgallium and allylaluminum sesquibromides

[reaction: see text] Fast transmetalation of an allyl group from indium to gallium enables the assembly of a catalytic cycle of indium, which accelerates the formation of allylgallium sesquibromide. A solution of allylaluminum sesquibromide in THF is also prepared from allyl bromide and aluminum metal under indium catalysis.     

Photochemistry of benzophenone immobilized in a major groove of DNA: formation of thermally reversible interstrand cross-link

We here report a highly site and sequence selective formation of an interstrand cross-link of (BP)U-containing oligomer duplexes. The cross-link was found spontaneously reverted to original oligomers upon heating, providing a new method for the temporary connection of two DNA strands.     

Regioselective photoallylations of dicyanopolycyclic aromatic compounds via electron transfer

Upon irradiation with allyltrimethylsilane, dicyanopolycyclic aromatic compounds undergo two modes of photoallylations, depending on the compounds and the reaction conditions. Both the photoreactions occur in a highly regioselective manner via electron transfer.     

Low-temperature viscoelasticity of poly-oxymethylene by radiation-induced solid-state polymerization of trioxane single crystal

Summary The polymerizate is a porous, white cylinder of polyoxymethylene, whose direction of crystal axis is unique. The dynamic viscoelasticity was measured by the vibrating-reed-method at –180° +10 °C. The existence of the -dispersion is doubtful in this sample. Therefore we can conclude that (i) the amorphous part is negligibly small both on the surface and inside of this sample, and (ii) the vibration of molecular chains is prohibited even on the surface of a single crystal.

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Zusammenfassung Das Polymerisat ist ein poröser, weißer Zylinder von Polyoxymethylen mit einheitlich ausgerichteter Kristallachse. Die dynamische Viscoelastizität wurde zwischen –180° und +10 °C nach der Methode des vibrierenden Stäbchens bestimmt. Die Existenz des-Dispersionsgebiets ist bei dieser Probe zweifelhaft. Wir können daher folgern, daß 1. der amorphe Anteil vernachlässigbar klein — sowohl an der Oberfläche wie im Innern — ist und daß 2. die Schwingung der Molekülketten sogar auch in der Grenzfläche eines Einkristalls behindert, unterbunden ist.

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This work was presented at the 43rd Annual Meeting of Virginia Academy of Science, Richmond, Virginia, May 7, 1965.     

Determination of the 17O NMR tensors in potassium hydrogen dibenzoate: a salt containing a short O...H...O hydrogen bond

Solid-state 17O NMR spectra were obtained at 4.70, 11.75 and 19.60T for potassium hydrogen [17O(4)]dibenzoate (PHB) under both magic-angle spinning and stationary conditions. Spectral analyses yielded both the magnitude and orientation of the 17O chemical shift (CS) tensor and the electric field gradient (EFG) tensor for each of the two chemically distinct oxygen sites in PHB. For the oxygen site that is not involved in hydrogen bonding, the experimental 17O NMR tensors are: delta(iso)=287+/-2 ppm, delta(11)=470+/-5 ppm, delta(22)=380+/-5 ppm, delta(33)=10+/-5 ppm, C(Q)=8.30+/-0.02 MHz, eta(Q)=0.23+/-0.05, alpha=0+/-5 degrees, beta=90+/-5 degrees, and gamma=30+/-5 degrees. For the oxygen site in the short O...H...O hydrogen bond, the experimental 17O NMR tensors are: delta(iso)=213+/-2 ppm, delta(11)=370+/-5 ppm, delta(22)=190+/-5 ppm, delta(33)=80+/-5 ppm, C(Q)=5.90+/-0.02 MHz, eta(Q)=0.55+/-0.05, alpha=5+/-5 degrees, beta=90+/-5 degrees, and gamma=90+/-5 degrees. Extensive quantum mechanical calculations at both restricted Hartree-Fock and density functional theory levels were performed to investigate the effects of an effectively symmetrical O...H...O hydrogen bond on 17O CS and EFG tensors.