解析 angle strain是由于分子中某相邻键的角度与该类正常键的键角相差很大引起的.例如环丙烷C-C-C的夹角为60度,这与饱和烃中C-C-Csp3键角109.5度相差很大,所以不稳定.一般说成,由于存在angle strain,因此环丙烷有开环的倾...结果一 题目 angle strain,torsional strain和steric strain之间有什么区别呀? 答案 ...
torsional strain是由于重叠式构象带来的空间张力，这种空间张力只有通过某个键的旋转才能释放。如重叠式乙烷只有通过C-C单键的旋转，转至交叉式才能解除这种torsional strain.steric strain是由于两个或几个体积大的基团在空间直接相遇，彼此的距离小于它们的范德华半径之和，而产生的相互排斥的力。例如叔卤...
答案解析 查看更多优质解析 举报 angle strain是由于分子中某相邻键的角度与该类正常键的键角相差很大引起的.例如环丙烷C-C-C的夹角为60度,这与饱和烃中C-C-Csp3键角109.5度相差很大,所以不稳定.一般说成,由于存在angle strain,因此环丙烷有开环的倾... 解析看不懂?免费查看同类题视频解析查看解答 ...
Tetrahedron Lett 1971;5:383-6.Cherest, M.; Felkin, H. The Influence of Steric and Torsional Strain on the Steric Course of Additions to Cyclohexanones. The Reaction between 4-t-Butylcyclohexanone and t-Butylallyl Mag- nesium Bromide. Tetrahedron Lett. 1971, 383....
We use a simple picture based on the pi electron approximation to study the band-gap variation of carbon nanotubes with uniaxial and torsional strain. We f... L Yang,MP Anantram,J Han,... - 《Physical Review B》 被引量: 544发表: 1999年 Torsional and steric control of stereoselectivity ...
the undesired pathway; (c) the classic Narasaka acylation is steric sensitive, and vinyltriphenylsilane displayed extremely low reactivity (Fig.2c). It is forseeable, the reaction would be more challenging if tetra(arylsilanes) were used. In the previous studies on the ring-opening reactions, we...
Dipak K. Mandal, in Stereochemistry and Organic Reactions, 2021 1.3.4.2 Origin of the torsional strain The origin of the rotational barrier (torsional barrier) has been much debated.11,12 The steric repulsion in the eclipsed conformation is at most a minor factor since the H atoms of the two...
For the entire series, there appears to be a delicate balance between angle and torsional deformation, but twisting appears to produce smaller relief from steric strain than angle bending. In the crystallographically characterized trisubstituted alkenes, the choice between the two is mainly determined ...
Torsional and steric control of stereoselectivity in isodicyclopentadiene cycloadditions An MM2 model to calculate the relative energies of stereoisomeric transition states of Diels-Alder reactions of isodicyclopentadiene and substituted deriva... FK Brown,KN Houk - 《Journal of the American Chemical Societ...
A good correlation was found in the plot of log k(rel) vs DELTA-SE, where DELTA-SE values were calculated from differences of MM-2 steric energy between olefins and a model of the corresponding triazoline cycloadduct. This finding indicates that the strain relief in the transition state is ...