Origins of thermodynamic stability of urea:alkane inclusion compounds

Article Abstract:

Thermodynamic stability of inclusion compounds of the urea:alkane type has been studied using existing thermodynamic data. Three alkane guests, decane, hexadecane and dodecane, were used. Up to their melting points, the inclusion compounds are thermodynamically stable relative to the component species. The solid-solid phase transitions have only a minor role in stabilization. The thermodynamic stability is mostly driven enthalpically. Above the melting point of the guest species, the inclusion compounds become far less stable as a result of competition from the liquid guest, and the destabilization brings incongruent melting as time goes on. At a given temperature, stability of the decane inclusion is lowest, and of the hexadecane is greatest, leaving that of dodecane in the middle.

Research, Lattice dynamics, Materials science, Materials, Petroleum refineries, Thermodynamics, Urea, Enthalpy

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The ultra high pressure conjugate addition of indoles to electron-deficient olefins

Article Abstract:

The addition to a series of Michael acceptors, that is, electron-deficient olefins, of indole and methyl indole at ultra-high and high pressures and ambient pressures in the presence of ytterbium triflate has been studied. Under ambient pressure less sterically hindered and more reactive electrophiles yielded 3-alkylated indoles, as expected, in yields that were good to excellent. The Michael acceptors that were more difficult were subjected to pressures of 13 kbar and in all cases a dramatic reduction in reaction product resulted. Products were characterized using single-crystal X-ray diffraction. Enals tended to polymerize.

Health aspects, Algae, Antineoplastic agents, Indole, Indoles

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