P-2-5 セミクラスレートハイドレートの相平衡と結晶構造の変化に与える四級ホスホニウム塩およびその側鎖の影響

抄録

In order to reveal the effects of phosphonium cations and the alkyl chains on the phase equilibrium behavior and the crystal structure of semiclathrate hydrates (SCHs), various tributylalkylphosphonium bromide semiclathrate hydrates (alkyl = n-propyl, n-butyl, n-pentyl, i-butyl, i-pentyl, and allyl) were investigated. The equilibrium temperatures of these phosphonium-salt-based SCHs are located at wide temperature range (274.1-288.8 K), which may be caused by interaction of water molecules with the phosphonium cations. Powder X-ray diffraction (PXRD) showed orthorhombic structures among almost the samples except the SCHs based on pentyl and allyl chains. Among the orthorhombic SCHs, the higher the equilibrium temperatures are, the larger the dissociation enthalpies get.