New Insights on the Mechanisms of the pH-Independent Reactions of Benzo[<i>a</i>]pyrene 7,8-Diol 9,10-Epoxides
作者:Lanxuan Doan、Bin Lin、Haruhiko Yagi、Donald M. Jerina、Dale L. Whalen
DOI:10.1021/ja004359z
日期:2001.7.1
10-tetrahydrobenzo[a]pyrene (1) and (+/-)-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (2) in water and dioxane-water mixtures have been determined over a pH range wider than that of earlier studies. This study provides additional insight on the mechanisms of the pH-independent reactions of 1 and 2. The rate profile for reaction of 1 shows acid-catalyzed hydrolysis at pH <5, a
(+/-)-7beta,8alpha-dihydroxy-9beta,10beta-epoxy-7,8,9,10-四氢苯并[a]芘(1)和(+/-)-7beta的反应速率和产物,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-四氢苯并[a]芘 (2) 在水和二恶烷 - 水混合物中的测定范围比早期研究更宽。这项研究提供了对 1 和 2 的 pH 非依赖性反应机制的额外见解。 1 的反应速率曲线显示了 pH <5 时的酸催化水解,pH 5-9.5 时的速率平台,pH 时的负拐点10-11.5,并且在 pH > 11.5 时速率增加。pH 10 和 pH 11.5 之间的速率下降伴随着四醇的产率从 60% (pH 8) 下降到 29% (pH 11。2) 并被解释为由于氢氧根离子作为碱的攻击使碳正离子中间体去质子化并在 pH > 10 时再生 1,从