3 research outputs found

    Asymmetric Synthesis of 4,8-Dihydroxyisochroman-1-one Polyketide Metabolites Using Chiral Hypervalent Iodine(III)

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    Stereoselective oxylactonization of <i>ortho</i>-alkenylbenzoate with chiral hypervalent iodine is applied to the asymmetric synthesis of 4-oxyisochroman-1-one polyketide metabolites including 4-hydroxymellein (<b>1</b>), a derivative of fusarentin <b>2</b>, monocerin (<b>3</b>), and an epimer of monocerin <i>epi</i>-<b>3</b>

    Crystal Structure and Cyclic Hydrogenation Property of Pr<sub>4</sub>MgNi<sub>19</sub>

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    The hydrogen absorption–desorption property and the crystal structure of Pr<sub>4</sub>MgNi<sub>19</sub> was investigated by pressure–composition isotherm measurement and X-ray diffraction (XRD). Pr<sub>4</sub>MgNi<sub>19</sub> consisted of two phases: 52.9% Ce<sub>5</sub>Co<sub>19</sub>-type structure (3R) and 47.0% Gd<sub>2</sub>Co<sub>7</sub>-type structure (3R). Sm<sub>5</sub>Co<sub>19</sub>-type structure (2H) and Ce<sub>2</sub>Ni<sub>7</sub>-type structure (2H) were not observed in the XRD profile. The Mg atoms substituted at the Pr sites in a MgZn<sub>2</sub>-type cell. The maximum hydrogen capacity reached 1.14 H/M (1.6 mass%) at 2 MPa. The hysteresis factor, Hf = ln­(<i>P</i><sub>abs</sub>/<i>P</i><sub>des</sub>), was 1.50. The cyclic hydrogenation property of Pr<sub>4</sub>MgNi<sub>19</sub> was investigated up to 1000 absorption–desorption cycles. After 250, 500, 750, and 1000 cycles, the retention rates of hydrogen were reduced to 94%, 92%, 91%, and 90%, respectively. These properties were superior to those of Pr<sub>2</sub>MgNi<sub>9</sub> and Pr<sub>3</sub>MgNi<sub>14</sub>

    Crystal Structure and Cyclic Hydrogenation Property of Pr<sub>4</sub>MgNi<sub>19</sub>

    No full text
    The hydrogen absorption–desorption property and the crystal structure of Pr<sub>4</sub>MgNi<sub>19</sub> was investigated by pressure–composition isotherm measurement and X-ray diffraction (XRD). Pr<sub>4</sub>MgNi<sub>19</sub> consisted of two phases: 52.9% Ce<sub>5</sub>Co<sub>19</sub>-type structure (3R) and 47.0% Gd<sub>2</sub>Co<sub>7</sub>-type structure (3R). Sm<sub>5</sub>Co<sub>19</sub>-type structure (2H) and Ce<sub>2</sub>Ni<sub>7</sub>-type structure (2H) were not observed in the XRD profile. The Mg atoms substituted at the Pr sites in a MgZn<sub>2</sub>-type cell. The maximum hydrogen capacity reached 1.14 H/M (1.6 mass%) at 2 MPa. The hysteresis factor, Hf = ln­(<i>P</i><sub>abs</sub>/<i>P</i><sub>des</sub>), was 1.50. The cyclic hydrogenation property of Pr<sub>4</sub>MgNi<sub>19</sub> was investigated up to 1000 absorption–desorption cycles. After 250, 500, 750, and 1000 cycles, the retention rates of hydrogen were reduced to 94%, 92%, 91%, and 90%, respectively. These properties were superior to those of Pr<sub>2</sub>MgNi<sub>9</sub> and Pr<sub>3</sub>MgNi<sub>14</sub>
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