Flash Photolytic Generation of <i>o</i>-Quinone α-Phenylmethide and <i>o</i>-Quinone α-(<i>p</i>-Anisyl)methide in Aqueous Solution and Investigation of Their Reactions in that Medium. Saturation of Acid-Catalyzed Hydration
作者:Y. Chiang、A. J. Kresge、Y. Zhu
DOI:10.1021/ja0120375
日期:2002.1.1
imidazolium ion, H2PO4-, (CH2OH)3CNH3+, (CH3)3CPO3H-, and HCO3- buffers. Acid-, base-, and uncatalyzed hydration reaction routes were again found, and solvent isotope effects as well as saturation of acid catalysis, this time in dilute HClO4, confirmed a preequilibrium mechanism for the acid-catalyzed reaction. Analysis of the buffer data gave buffer-base rate constants that did not conform to the
通过邻羟基-α-苯基苯甲醇的闪光光解,邻醌α-苯基甲基化物在水溶液中作为一种短寿命的瞬态物质产生,其衰变速率在HClO4和NaOH溶液以及CH3CO2H、H2PO4中测量- 和 HCO3- 缓冲液。这些数据表明,这种醌甲基化物水合回其苯甲醇前体是通过酸、碱和非催化途径发生的。酸催化反应产生溶剂同位素效应 kH+/kD+ = 0.34,其相反性质表明该反应是通过醌甲基化物在其羰基氧原子上的快速预平衡质子化,然后用水对随后的碳阳离子中间体进行定速捕获而发生的,这一结论得到了浓 HClO4 溶液中酸催化饱和的支持。邻醌α-(对茴香基)甲基化物也通过相应的苯甲醇和该醇的对氰基苯酚醚的闪光光解产生,并且在HClO4和NaOH溶液以及HCO2H中测量其衰变速率、CH3CO2H、HN3、CF3CH2NH3+、咪唑鎓离子、H2PO4-、(CH2OH)3CNH3+、(CH3)3CPO3H- 和 HCO3-