Etude par spectre UV du dimesitylcarbene forme par photolyse du dimethyl diazomethane. Equilibre entre les etats singulet et triplet du carbene. L'etat singulet reagit avec le methanol, le propanol-1 et le cyclohexadiene-1,3, alors que l'etat triplet se dimerise en olefine ou reagit avec l'oxygene
Etude par spectre UV du dimesitylcarbene forme par photolyse du 二甲基重氮甲烷。Equilibre entre les etats singulet 和三重卡宾。L'etat singulet avec le 甲醇, le propanol-1 和 le cyclohexadiene-1,3, alors que l'etat 三重酶二聚体 en 烯烃 ou reagit avec l'oxygene
Dimesitylcarbene: the distinct chemistries of its singlet and triplet states
作者:Avtar S. Nazran、David Griller
DOI:10.1039/c39830000850
日期:——
Dimesitylcarbene is unique amongst the diarylcarbenes thus far investigated since its triplet state cannot readily convert into the singlet state.
迄今为止,在二芳基卡宾中,二苯甲基卡宾是独特的,因为其三重态不能轻易转化为单重态。
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。
Resolution and enantiomerization barrier of tetramesitylethylene
作者:Erez Gur、Yuriko Kaida、Yoshio Okamoto、Silvio E. Biali、Zvi Rappoport
DOI:10.1021/jo00039a033
日期:1992.6
The H-1 NMR spectrum of tetramesitylethylene (2) was analyzed, and the signals were assigned by means of a 2D NOESY spectrum. Attempts to observe anisochrony of the enantiotopic groups of a racemic mixture of 2 in a chiral solvent by H-1 NMR were unsuccessful. Molecular mechanics and MNDO calculations satisfactorily reproduce the ground-state conformation. The calculated barrier for the enantiomerization process is 21.8 (MM2) and 28.2 (MNDO) kcal mol-1. 2 was chromatographically resolved on a (+)-poly(triphenylmethyl)methacrylate (PTrMA) column. Its specific rotation is [alpha]25 = -12100-degrees at 365 nm and -2300-degrees at 589 nm (D line). The activation parameters for the enantiomerization of 2 in perhydrofluorene are DELTA-G(double dagger) = DELTA-H(double dagger) = 39.6 kcal mol-1 and DELTA-S(double dagger) = 0 cal mol-1 K-1. The barrier for 2 is the highest determined experimentally for a correlated rotation.