Kinetic investigations of the reactions of hinderedphenols with<i>N</i>-fluoro-1,4-diazoniabicyclo[2.2.2]octanesalt analogues
作者:Stojan Stavber、Marjan Jereb、Marko Zupan
DOI:10.1002/poc.444
日期:2002.1
bis(tetrafluoroborate) (Selectfluor™, F-TEDA-BF4) in acetonitrile in the absence or presence of various sources of external nucleophile (alcohols, water, trifluoroacetic acid) were studied. The reactions exhibited overall second-order kinetics, whereas products formation was strongly dependent on reaction conditions. Fluorination took place in neat MeCN; in the presence of water or alcohols, para quinols or
受阻酚(2,4,6-三甲基苯酚,2,6-二-的反应的动力学叔丁基-4-甲基苯酚和2,4,6-三-叔丁基苯酚)与1-氟-4-氯甲基在没有或存在各种外部亲核试剂(醇,水,三氟乙酸)的条件下,研究了乙腈中的-1,4-二氮杂双环[2.2.2]辛烷双(四氟硼酸酯)(Selectfluor™,F-TEDA-BF 4) 。反应表现出整体的二级动力学,而产物的形成强烈依赖于反应条件。氟化反应在纯净的MeCN中进行;在水或酒精,对羟基喹啉或对羟基苯甲酸存在下喹啉醚是唯一形成的;在酸性条件(TFA)下,发现Ritter型酰胺化是主要过程。发现二阶速率常数k 2的值取决于目标苯酚的结构,并且随着底物的体积而减小。甲醇稍微提高了速率,而水则大大降低了速率。获得了活化焓(在72和78 kJ mol -1之间)和活化熵(在-5和-42 J mol -1 K -1之间)。发现受阻较少的底物的活化熵较高,这表明速率确定步骤主要受空间因素调节。log