Reestimation of the Taft's substituent constant of the pentafluorophenyl group
Reestimation of the Taft's substituent constant of the pentafluorophenyl group
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DOI：
10.1021/jo048939g
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发表时间：
2004-10-15
影响因子：
3.6
通讯作者：
Sakai, T
中科院分区：
文献类型：
--
作者：
Korenaga, T;Kadowaki, K;Sakai, T
通过3-苯基丙酸和丁酸的一系列酯（涉及五氟苄基）的红外光谱数据（u（C=O））和sigma* 常数之间的相关性，重新估计五氟苯基的塔夫脱取代基常数（sigma*（C6 F5））为1.50。通过对3-苯基丙酸五氟苄酯稳定构象及其羰基频率的从头算和密度泛函理论计算，排除了分子内C6 F5和C6 H5基团之间的π-π相互作用干扰相关性的可能性.重新估计的σ *（C6 F5）值用于计算五氟苯甲醇的pK（a）值[14.5（或14.3）]。
The Taft's substituent constant of the pentafluorophenyl group (sigma*(C6F5)) was reestimated to be 1.50 by correlation between IR spectral data (u(C=O)) and sigma* constants for a series of esters (involving the pentafluorobenzyl group) of 3-phenylpropanoic acid and butanoic acid. The possibility of the disturbance of the correlation by the intramolecular pi-pi interaction between C6F5 and C6H5 groups in pentafluorobenzyl 3-phenylpropanoate was excluded by ab initio and DFT calculations of the stable conformations and their carbonyl frequencies. The reestimated (sigma*(C6F5) value was used for calculation of the pK(a) value of pentafluorobenzyl alcohol [14.5 (or 14.3)].