Photo-heterolysis and -homolysis of substituted diphenylmethyl halides, acetates, and phenyl ethers in acetonitrile: characterization of diphenylmethyl cations and radicals generated by 248-nm laser flash photolysis
作者:J. Bartl、S. Steenken、H. Mayr、R. A. McClelland
DOI:10.1021/ja00175a028
日期:1990.9
cations with R = R' = Me to R = H, R' = CF3. The rate constants for reaction of C+ with halides (ion recombination) are -2 X 1O1O M-l s-' (diffusion control). The radicals C' disappear by dimerization and disproportionation, for which a complete mass balance has been achieved by product analysis for the case of the benzhydryl system. At laser-pulse powers > IO mJ electronically excited radicals, C", are
异裂比均裂吸热小得多。均裂和异裂也可以通过与三线态苯乙酮(由 308 nm 光解产生)的反应间接实现。除非被一种或多种 MeO 稳定,否则阳离子主要通过与乙腈反应生成腈离子而衰变。然而,由于该反应是可逆的(如二苯甲基阳离子所示),腈离子对最终(阳离子衍生)产物的形成贡献很小,这是由与痕量水(主要产物,二苯甲基醇)反应产生的。 ; 次要,二苯甲基乙酰胺)。对于 R = R' = Me 到 R = H,R' = CF3 的阳离子,C+ 加到 CH$N 的速率常数在 3.5 X 105 到 3.8 X IO7 sI 的范围内。C+ 与卤化物(离子复合)反应的速率常数为 -2 X 1O1O Ml s-' (扩散控制)。自由基C'通过二聚和歧化消失,对于二苯甲基体系的情况,通过产物分析已经实现了完全的质量平衡。在激光脉冲功率 > 10 mJ 时,通过基态 C' 吸收光量子,在许多情况下另外形成电子激发自由基
Effects of<i>para</i>-Substituents on the Reactivities of Sterically Congested Triplet Diphenylcarbenes
作者:Yingmo Hu、Katsuyuki Hirai、Hideo Tomioka
DOI:10.1246/cl.2000.94
日期:2000.2
Kinetically stabilized triplet di(2,6-dimethylphenyl)carbene is thermodynamically stabilized further by a spin-delocalizing para-substituent, whereby making the persistent triplet carbene longer-lived.
Nauta; Wuis, Recueil des Travaux Chimiques des Pays-Bas, 1938, vol. 57, p. 41,56
作者:Nauta、Wuis
DOI:——
日期:——
Evidence for single electron transfer in the reduction of alcoholswith lithium aluminum hydride
作者:E.C. Ashby、A.B. Goel
DOI:10.1016/s0040-4039(01)90466-6
日期:1981.1
EPR evidence supporting a single electrontransfer mechanism in the reduction of secondary and tertiary alcohols to hydrocarbons with LiAlH4 is presented.
EPR证据支持用LiAlH 4将仲醇和叔醇还原为烃类的单一电子转移机理。
Polymethylated and Poly(<i>tert</i>)butylated Diphenylcarbenes. Generation, Reactions, Kinetics, and Deuterium Isotope Effects of Sterically Congested Triplet Carbenes
Dimesitylcarbene (2a) was shown to decay by undergoing dimerization and to have a half-life of 160 ms, some 5 orders of magnitude longer-lived than diphenylcarbene. Didurylcarbene (2b) was twice as long-lived as 2a, while decamethyldiphenylcarbene (2c) decayed mainly unimolecularly by abstracting H from the o-methyl group and became shorter-lived than 2b. 2,4,6-Tri(tert-butyl)diphenylcarbene (14) decayed
Dimesitylcarbene (2a) 显示通过二聚作用而衰变,半衰期为 160 ms,比二苯基卡宾长约 5 个数量级。二十二烷基卡宾 (2b) 的寿命是 2a 的两倍,而十甲基二苯基卡宾 (2c) 主要通过从邻甲基中提取 H 以单分子方式衰变,并且比 2b 寿命更短。2,4,6-三(叔丁基)二苯基卡宾 (14) 几乎完全通过从邻叔丁基中提取 H 进行单分子衰变,并显示出 125 μs 的寿命。2c 和 14 的 H 和 D 提取的阿伦尼乌斯图提供了与经典原子转移反应一致的数据,尽管两个系统之间的动力学参数非常不同。