Sulfur Radical Cations. Kinetic and Product Study of the Photoinduced Fragmentation Reactions of (Phenylsulfanylalkyl)trimethylsilanes and Phenylsulfanylacetic Acid Radical Cations
作者:Enrico Baciocchi、Tiziana Del Giacco、Fausto Elisei、Andrea Lapi
DOI:10.1021/jo051145x
日期:2006.2.1
D2O. Pyridines too were found to accelerate the decarboxylation rate of 3+• and 4+•. The rate increase, however, was not a linear function of the base concentration, but a plateau was reached. A fast and reversible formation of a H-bonded complex between the radical cation and the base is suggested, which undergoes C−C bond cleavage. It is probable that the H-bond complex undergoes first a rate determining
激光和稳态光解,通过NMQ致敏+,PhSCH的(R)X 1 - 4(R = H中,Ph; X森达3,CO 2 H)为在CH进行3 CN。清楚地显示了1 + • − 4 + •的形成。所有自由基阳离子都经历快速的一级断裂反应,其中C-Si键以1 + •和2 + •裂解,而C-C键以3 + •和4 + •裂解。的去甲硅烷基化反应1 + •和2 + •受到亲核辅助,在H 2 O存在下3 + •和4 + •的脱羧速率增加。当H 2 O被D 2取代时,观察到氘的动力学同位素效应为2.0。O.吡啶也被发现可以加速3 + •和4 + •的脱羧速度。然而,速率增加不是碱浓度的线性函数,而是达到平稳。建议在自由基阳离子和碱之间快速且可逆地形成H键复合物,然后进行CC键断裂。H键络合物可能首先经历确定质子偶联电子转移的速率,从而形成羧基自由基,然后失去CO 2。稳态光解研究表明,PhSCH 3是1和3形成的唯一产物,而[PhS(Ph)CH-]