作者:Mirjana Eckert-Maksić、Zoran Glasovac、Pavle Trošelj、Agnes Kütt、Toomas Rodima、Ivar Koppel、Ilmar A. Koppel
DOI:10.1002/ejoc.200800673
日期:2008.10
was shown that basicity ordering of the bases with dimethylaminopropyl substituents in acetonitrile follows the trend encountered in the gas phase. However, this is not the case for the methoxypropyl-substituted guanidines indicating that in these molecules formation of the intramolecular hydrogen bonds is to large extent hindered due to solvation by acetonitrile.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451
使用紫外/可见分光光度法滴定法在乙腈 (MeCN) 中测定了七种新型胍衍生物的 pKa 值,其中六种具有能够形成分子内氢键的杂烷基取代基。获得的 pKa 值范围从 24.7 到 27.2。在研究的胍中,最基本的被发现是大约。比众所周知的超强碱 N1,N1,N3,N3-四甲基胍 (TMG) 碱性强 4 个 pKa 单位。将测得的 pKa 值变化趋势与实验(由扩展动力学方法确定)和理论 [B3LYP/6-311+G(2df,p)//B3LYP/6-31G(d)] 气体进行比较-相质子亲和力。结果表明,乙腈中带有二甲基氨基丙基取代基的碱的碱性排序遵循气相中遇到的趋势。然而,