Radical and Non-Radical Mechanisms for Alkane Oxidations by Hydrogen Peroxide−Trifluoroacetic Acid
作者:Donald M. Camaioni、J. Timothy Bays、Wendy J. Shaw、John C. Linehan、Jerome C. Birnbaum
DOI:10.1021/jo005617d
日期:2001.2.1
forms initially but then esterifies to cyclohexyl trifluoroacetate. Small amounts of trans-1,2-cyclohexadiyl bis-(trifluoroacetate) also form. Although these products form irrespective of the presence or absence of O2, dual mechanisms are shown to operate. In the absence of O2, the dominant mechanism is a radical chain reaction that is propagated by CF3. abstracting H from C6H12 and SH2 displacement of
再次讨论了H 2 O 2-三氟乙酸体系对环己烷的氧化。与先前的报道(Deno,N。; Messer,LA Chem.Comm.1976,1051)一致,环己醇最初形成,但随后酯化为三氟乙酸环己酯。也形成少量的反式1,2-环己二基双(三氟乙酸酯)。尽管这些产品的形成与氧气的存在或不存在无关,但显示出双重机理。在没有O2的情况下,主要机制是CF3传播的自由基链反应。从C6H12提取H和C6H11的SH2位移。在CF3CO2OH上。C6H11的中介。和CF3。当使用环己烷-d12时,由CHF3和CO2以及三氟环己基乙酸酯或CDF3的产生推导得出。在O2存在下,氟仿和CO2被抑制,反应速度变慢,速率定律接近二阶(过酸和C6H12中的一阶)。除在升高的温度(约75摄氏度)下,喹喔啉对环己基自由基的捕获效率很低。当喹喔啉存在于室温反应中时,不会产生氟仿和CO2,这是链式通路的可靠证据。这些观察结果表明