Equilibrium Ion Pair Acidities of Polyhalogenated Benzenes in THF. Extrapolation to Benzene<sup>1</sup>
作者:Manolis Stratakis、Peng George Wang、Andrew Streitwieser
DOI:10.1021/jo9516401
日期:1996.1.1
pair acidities of six polyfluorobenzenes at 25 degrees C and six polychlorobenzenes at -20 degrees C were determined in THF. For fluorinated benzenes the additive (negative) effects of fluorine on pK (partial equilibrium factors) are o = 5.2, m = 3.0, and p = 1.4. From these the cesium ion pair pK (per H) of benzene is extrapolated to be 44.8 at 25 degrees C. For chlorobenzenes the additive contributions
在THF中测定了在25℃下的六个多氟苯和在-20℃下的六个多氯苯的平衡铯离子对酸度。对于氟化苯,氟对pK(部分平衡因子)的加(负)效应为o = 5.2,m = 3.0,p = 1.4。从这些推断出,铯的铯离子对pK(每H)在25摄氏度下推算为44.8。对于氯苯,邻氯,间氯和对氯的添加剂贡献分别为4.2、2.7和2.1。苯的相应pK在-20摄氏度下为47.0。聚集研究表明,在10(-)(3)-10(-)(4)M的浓度范围内,1,2,4,5-四氯苯铯盐1,2,4,5-四氟苯的铯盐和锂盐是单体的。Li级的苯的pK推断为39.5。