Effects of Structure on 1-Octanol/Water Partitioning Behavior of Aliphatic Amines and Ammonium Ions†
Effects of Structure on 1-Octanol/Water Partitioning Behavior of Aliphatic Amines and Ammonium Ions†
复制标题
结构对脂肪胺和铵离子 1-辛醇/水分配行为的影响†
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
T. Fujita
中科院分区：
文献类型：
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作者：
C. Takayama;M. Akamatsu;T. Fujita
采用取代基自由能常数和多元回归技术，测定了45种中性脂肪胺在正辛醇/水体系中的分配系数和66种脂肪胺离子与苦味酸根的离子对形成-分配平衡常数。通过方程logK = a∑π + ρI∑σI ∑δiE（Ri）+ bnH + c定量分离了N-取代基的疏水、电子、空间和氢键效应对分配行为的影响，其中K为平衡常数，ρI、δi、B和c为磁化率常数和截距。∑π和∑σI分别为三个或四个N-取代基的疏水性π值和诱导电子σI值之和。E（Ri）是考虑到N-取代基Rj的支化效应而从Dubois E′值导出的修改的空间常数，其中对于胺i = 1 <$3，对于铵离子i = 1 <$4。Ri根据E值的相对大小进行分类，使得E（R1）≤ E（R2）≤ E（R3）≤ E（R4）。nH是（共轭）铵离子的NH氢的数目。结果表明，用N-取代基的E常数可以很好地解释离子配对中的空间位阻效应。
The partition coefficients of 45 neutral aliphatic amines and the ion-pair formation-partition equilibrium constants with picrate of 66 aliphatic ammonium ions, determined using a 1-octanol/water system, were analyzed by means of free-energy-related substituent constants and the multiple regression technique. The hydrophobic, electronic, steric, and hydrogen bonding effects of N-substituents governing the partitioning behaviors were quantitatively separated by means of an equation: log K = a∑π + ρI∑σI ∑δiE (Ri) + bnH + c, where K is the equilibrium constant, and ρI, δi, b, and c are susceptibility constants and the intercept. ∑π and ∑σI, are, respectively, the sum of the hydrophobic π values and the inductive electronic σI values of three or four N-substituents. E (Ri) is a modified steric constant derived from the Dubois E′s value considering the branching effect of N-substituents, Rj, in which i = 1 ∼ 3 for amines and i = 1 ∼ 4 for ammonium ions. Ri is classified according to the relative magnitude of E values so that E (R1) ≤ E (R2) ≤ E (R3) ≤ E (R4). nH is the number of NH hydrogens of the (conjugate) ammonium ion. It was shown that the definitely intermolecular type of steric effect in the ion-pairing is nicely elucidated with the E constant of component N-substituents.