作者:M. Green、S. C. Pearson
DOI:10.1039/j29690000593
日期:——
ruling out a mechanism involving the rate-determining formation of 2,4,6-trimethylbenzoylium cation. Examination of the oxygen-18 content of recovered 2,4-dinitrophenyl ether of (II) labelled at the carbonyl group after the ether had been subjected to solvolytic conditions, i.e. sodium hydroxide in dioxan–water, showed no loss of oxygen-18. The mechanism of the Beckmann fragmentation reaction is discussed
α-酮肟PhCO·C(Ph)NOH(I)和2,4,6-Me 3 C 6 H 2 CO·C(Ph)反型的2,4-二硝基苯醚的处理NOH(II)与亲核试剂OH -,OME -,OPR异通向贝克曼碎片与苄腈的形成及相应的苯甲酸或2,4,6-三甲基酸。苯甲肟肟醚与BuO t –和NH 3之间发生类似的反应,而这些亲核试剂取代了(II)醚的2,4-二硝基苯基环。(II)与OH的2,4-二硝基苯基醚的反应-,OME -和OPr i –遵循二阶动力学,排除了涉及速率确定2,4,6-三甲基苯甲酰基阳离子形成的机理。在醚经受溶剂化条件后,即回收在羰基上标记的(II)的(II)的回收的2,4-二硝基苯基醚中氧-18含量的检查。在二恶烷水中的氢氧化钠溶液没有显示出18的氧损失。根据这些观察结果,讨论了贝克曼片段化反应的机理。当将(I)和(II)的2,4-二硝基苯基醚在乙腈或苯中加热时,形成苄腈和2,4-二硝基苯