A New Class of Organosuperbases, N-Alkyl- and N-Aryl-1,3-dialkyl-4,5-dimethylimidazol-2-ylidene Amines: Synthesis, Structure, pKBH+ Measurements, and Properties
作者:Roman A. Kunetskiy、Svetlana M. Polyakova、Jiří Vavřík、Ivana Císařová、Jaan Saame、Eva Roos Nerut、Ivar Koppel、Ilmar A. Koppel、Agnes Kütt、Ivo Leito、Ilya M. Lyapkalo
DOI:10.1002/chem.201102249
日期:2012.3.19
A series of stable organosuperbases, N‐alkyl‐ and N‐aryl‐1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐ylidene amines, were efficiently synthesized from N,N′‐dialkylthioureas and 3‐hydroxy‐2‐butanone and their basicities were measured in acetonitrile. The derivatives with tert‐alkyl groups on the imino nitrogen were found to be more basic than the tBuP1(pyrr) phosphazene base in acetonitrile. The origin of the
从N,N'-二烷基硫脲和3-羟基-2-丁酮有效合成了一系列稳定的有机超碱N-烷基和N-芳基-1,3-二烷基-4,5-二甲基咪唑-2-亚胺并用乙腈测量其碱性。发现亚氨基氮上带有叔烷基的衍生物比乙腈中的t Bu P 1(pyrr)磷腈碱更具碱性。讨论了这些化合物的高碱性的起源。在乙腈和气相中,烷基亚氨基衍生物的碱度取决于亚氨基上取代基的大小,这会影响咪唑环的芳构化程度,具体方法如下:13 C NMR化学位移或通过计算的ΔNICS(1)芳香度参数以及对溶剂化的影响。如果在分析中处理范围更广的亚氨基取代基,包括电子受体取代基,则芳构化的影响较小,气相的碱度更依赖于场致效应,极化率和共振效应。取代基。