Kinetics of proton transfer from phosphonium ions to electrogenerated bases: polar, steric and structural influences on kinetic acidity and basicity
作者:Ana-Paula Bettencourt、Ana Maria Freitas、M. Irene Montenegro、Merete Folmer Nielsen、James H. P. Utley
DOI:10.1039/a708086g
日期:——
linear sweep voltammetry (LSV) have been used to measure rates of proton transfer in DMSO solution between different types of electrogenerated base (EGB) and a series of phosphonium ions of relevance to ylide formation for synthetic reactions. Although the electrochemical methods are convenient for the measurement of rates of proton transfer in these systems a major conclusion of the study is that considerable
导数循环伏安法(DCV)和线性扫描伏安法(LSV)已用于测量DMSO溶液中质子在不同类型的电生成碱(EGB)与一系列与叶立德形成有关的合成反应之间的transfer离子转移速率。尽管电化学方法可方便地测量这些系统中的质子转移速率,但这项研究的主要结论是,在应用这些方法并从结果中得出一般结论时必须格外小心。尤其是将动酸度与热力学p K进行比较DMSO中的值表明,一系列Br离子不满足单个布朗斯台德关系。动酸度受到以下因素的严重影响:EGB是碳还是氮碱;一些the离子的烯醇化倾向;和空间因素。在酸性亚甲基上的其他电子需求量度(13 C和1 H化学位移,还原电位)与p K(DMSO)值一致。动力学结果证实,对于不可烯醇化的salts盐,Ph 3 P +基团比Bu 3 P +更具活化性。