电化学监测酸碱滴定法测定(R—H)^(+·)键的异裂自由能  

Heterolytic (R-H)^(+·) Bond Dissociation Free Energies in Solution Derived from Electrochemically-monitored Acid-Base Titration(EABT)

作　　者：曾青[1] 何家骐[1] 程津培[1] 

机构地区：[1]南开大学化学系,天津300071

出　　处：《高等学校化学学报》2002年第7期1285-1290,共6页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金 (批准号 :2 93 92 2 0 6)

摘　　要：建立一种电化学监测酸碱滴定 (EABT)方法 ,利用循环伏安 (CV)技术直接观测正离子基 (RH+· )酸解过程中各物种浓度的变化 ,从而得到酸性离解常数 (p KRH+· )和键异裂自由能 (ΔGhet) .所测吩噻嗪系列在二甲基亚砜和乙腈中的 p KRH+· 与文献中用间接法得到的 p KRH+· 值相当吻合 ,证实了本方法的可信度 .由于不需要间接方法所必需的中性母体分子的 p Ka 和负离子氧化电位 ,故该方法可适用于难于测定的大量有机体系 p KRH+·An Electrochemically Monitored Acid Base Titration(EABT) method using cyclic voltammetry was established to measure directly the concentration change of all species, then to get the acidic dissociation constants(p K RH +· ) and bond heterolysis energies(Δ G het ) of radical cations. p K RH +· s of phenothiazine and its analogues in dimethylsulfoxide and acetonitrile were obtained and in good accordance with the p K RH +· s derived from indirect methods. So, the credence of the present method was tested. Because the exact values of p K a(or BDE) of the parent molecules and of the anion oxidation potentials needed by indirect methods are not required, the EABT method can be applicable to a wide range of organic systems whose p K RH +· s may otherwise be difficult to be obtained.

关 键 词：电化学监测 酸碱滴定法 测定 (R-H)^+·键 异裂自由能 RH^+· 酸性离解常数 正离子基 循环伏安 有机反应 

分 类 号：O657.1[理学—分析化学] O621.25[理学—化学]