Showing papers by "Kwang S. Kim published in 1987"

Hydration structures and energetics of phospholipid

Abstract: Using previously reported ab initio potentials of the intermolecular interaction energies of phospholipid (PL), Lysophosphatidyl Ethanolamine, with one Na+ ion and one water molecule, we performed Monte Carlo simulations for PL‐water and PL‐Na+‐water systems. Water‐water and PL‐water interaction energetics of PL hydration sites are analyzed to understand, in a qualitative way, why the PL head part shows hydrophilicity and the tail part shows hydrophobicity. The interaction of Na+ with PL, as well as the interaction of water with PL, is visualized from the analysis of the hydration structures near PL, and the radial distribution functions are analyzed for selected hydration sites. The PL molecule shows much stronger interaction with Na+ than with water. The Na+ ion is likely to be strongly bound to PO 4− , even to the extent of being trapped, whereas, for water, there exist two strong binding regions near NH 3+ and PO 4− . Three water molecules near NH 3+ are much more strongly bound than four water molecules near the double‐bonded oxygens of PO 4− . The hydrogens of CH2 adjacent to NH 3+ show somewhat strong hydrophilicity, while the hydrogens of CH2 adjacent to PO 4− does not show such characteristics. The CH2 groups at the PL tail part give repulsive interactions with water molecules, showing hydrophobicity. Water molecules near the PL tail are stabilized only by water‐water interactions.

Direct Conversion of Oximes and Hydrazones into Their Ketones with Dinitrogen Tetroxide.

Abstract: Treatement of various oximes and hydrazones with dinitrogen tetroxide(N 2 O 4 ) at low temperature in acetonitrile gave the corresponding ketones respectively in excellent yields.

Facile Synthesis of Azides: Conversion of Hydrazines Using Dinitrogen Tetroxide.

Abstract: Various hydrazines such as aryl-, carbonyl-, and sulfonyl-hydrazine were reacted with dinitrogen tetroxide to give the corresponding azides in excellent yields under mild conditions at low temperature(−20~− 40 °C) in acetonitrile.