SOLVATOCHROMIC COMPARISON METHOD .1. BETA-SCALE OF SOLVENT HYDROGEN-BOND ACCEPTOR (HBA) BASICITIES
SOLVATOCHROMIC COMPARISON METHOD .1. BETA-SCALE OF SOLVENT HYDROGEN-BOND ACCEPTOR (HBA) BASICITIES
复制标题
DOI：
10.1021/ja00418a009
复制
发表时间：
1976-01-01
影响因子：
15
通讯作者：
TAFT, RW
中科院分区：
文献类型：
--
作者：
KAMLET, MJ;TAFT, RW
概述了溶致变色比较法。HBA中溶剂化变色位移增强的幅度本文测定了4-硝基苯胺（1）相对于MA-二乙基-4-硝基苯胺（2）[-（1-2）b_h_2n]和4-硝基苯酚（3）相对于4-硝基苯甲醚（4）[-（3-4）-ho]的HBD值（氢键供体）底物1和3在相应的HBA溶剂中显示彼此成比例，与4-氟苯酚与相同HBA的氢键络合物的限制19 F NMR位移成比例，与4-氟苯酚（pKhb）和苯酚与同一HBA分子的氢键络合物的对数缔合常数呈线性关系。LFE关系被用来建立溶剂HBA碱度的/3标度。虽然在红外线中自由和键合XH伸缩振动之间的频率差更经常地被用作氢键强度的量度，但在这方面，紫外-可见光谱数据的溶剂化显色比较可以提供同样有用的信息。本文用溶致变色比较法构造了溶剂氢键受体能力的1/3标度（λ ~ λ）。
The solvatochromic comparison method is outlined. Magnitudes of enhanced solvatochromic shifts in HBA (hydro-gen-bond acceptor) solvents are determined for 4-nitroaniline (1) relative to MA-diethyl-4-nitroaniline (2)[—(1-2) b_h2n] and for 4-nitrophenol (3) relative to 4-nitroanisole (4)[—(3-4)—ho]· The—values for the HBD (hydro-gen-bond donor) substrates 1 and 3 in corresponding HBA solvents are shown to be proportional to one another, proportional to limiting 19F NMR shifts of hydrogen-bonded complexes of 4-fluorophenol with the same HBA’s, and linearwith log asso-ciation constants of hydrogen-bonded complexes between 4-fluorophenol (pKhb) and phenol and the same HBA molecules. The LFE relationships are used to establish a/3-scale of solvent HBA basicities.Although frequency differences between free and bonded XH stretching vibrationsin the infrared are more frequently used as measures of hydrogen-bond strengths, sol-vatochromic comparisons of uv-visible spectral data can provide equally useful information in this regard. In this paper we will use the solvatochromic comparison method to construct a/3-scale of solvent hydrogen-bond acceptor ability (ß~