Hydrophobicity parameter of diazines. III: Relationship of partition coefficients of monosubstituted diazines and pyridines in different partitioning systems.
The logarithm of the 1-octanol-water partition coefficient value (log Poct) was compared with those from CHCl3-water (log PCL) and di-n-butyl ether-water (log PE) for (di)azines substituted singly by nonhydrogen-bonding and hydrogen-accepting substituents (2-substituted pyrazines, 2-substituted pyrimidines, 5-substituted pyrimidines, and 2-substituted pyridines). The difference between log Poct and log PCL for diazines was primarily governed by the number of hydrogen-bonding sites in the substituent. For 2-substituted pyridines, the difference in the hydrogen-bonding association of the ring N-atom with octanol from that with CHCl3 was also significant. In the relationship between log Poct and log PE, the hydrogen-bonding solvations of the ring N-atom(s), as well as the hydrogen-accepting substituent with octanol, should be taken into account because the butyl ether acts as a nonhydrogen-bonding solvent.
Yamagami
C
C
Kobe Women's College of Pharmacy, Japan.
Takao
N
N
Fujita
T
T
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006860:Hydrogen Bonding; D000442:Octanols; D011719:Pyrazines / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D012995:Solubility; D012997:Solvents; D014867:Water
D000442:Octanols; D011719:Pyrazines; D011725:Pyridines; D011743:Pyrimidines; D012997:Solvents; D014867:Water