作者:D. A. Lawlor、R. A. More O’Ferrall、S. N. Rao
DOI:10.1021/ja806899d
日期:2008.12.31
The phenathrenonium ion is formed as a reactive intermediate in the solvolysis of 9-dichloroacetoxy-9,10-dihydrophenanthrene in aqueous acetonitrile and undergoes competing reactions with water acting as a base and nucleophile. Measurements of product ratios in the presence of azide ion as a trap and 'clock' yield rate constants kp = 3.7 x 10(10) and kH2O = 1.5 x 10(8) s(-1), respectively. Combining
菲鎓离子在 9-二氯乙酰氧基-9,10-二氢菲在乙腈水溶液中的溶剂分解中作为反应中间体形成,并与作为碱和亲核试剂的水发生竞争反应。在叠氮离子作为陷阱和“时钟”收益率常数 kp = 3.7 x 10(10) 和 kH2O = 1.5 x 10(8) s(-1) 的情况下测量产品比率。将这些与逆反应(菲质子化和酸催化其水加合物的芳构化)的速率常数相结合,得到平衡常数 pKa = -20.9 和 pK(R) = -11.6。对于一系列砷和苄基阳离子,log kp 与 pKa 的相关性,考虑到由水的弛豫 (10(11) s(-1)) 设定的 kp 限制,导致外推 kp = 9.0 x 10 (10) s(-1) 和 pKa = -24。苯鎓离子为 5,1-萘鎓离子 kp = 6.5 x 10(10) s(-1) 和 pKa = -22.5。将这些 pKa 与苯和萘水合的平衡常数 pKH2O 的估计值以及基于赫斯定律的