The strain energy for methylenecyclohexane has been calculated to be 4.5 kcalmol−1using estimations for 1,3-diaxial strain (0.9 kcalmol−1), methyl/hydrogen allylic strain (1.3kcalmol−1), and methyl/methyl allylic strain (7.6 kcalmol−1) values.[2] The strain energy in 1,8-...
The strain energy for methylenecyclohexane has been calculated to be 4.5 kcalmol −1 using estimations for 1,3-diaxial strain (0.9 kcalmol −1 ), methyl/hydrogen allylic strain (1.3kcalmol −1 ), and methyl/methyl allylic strain (7.6 kcalmol −1 ) values. [2] The strain ...
1 using estimations for 1,3-diaxial strain (0.9 kcalmol?1), methyl/hydrogen allylic strain (1.3kcalmol?1), and methyl/methyl allylic strain (7.6 kcalmol?1) values. HYPERLINK /wiki/Allylic_strain \l cite_note-J1968-2#cite_note-J1968-2 [2] The strain energy in 1,8-dimethyl...
I strain 内张力F strain 前张力B strain 后张力Anomeric effect 端基异构效应Walden inversion 瓦尔登反转Racemization 外消旋化Isoinversion 等反转Isoracemization 等消旋Homochiral 纯手性[的]Mechanism 机理Unimolecular nucleophilic 单分子亲核取代Bimolecular nucleophilic sub-stitution 双分子亲核取代Bimolecular nucleophilic...
Allylic strain caused by N -substituents shifts strongly the a,ee, a equilibria in trans -4,6-diphenyl- and cis -4,5-diphenyl-oxazinones, but only moderately the e,ea,a equilibria in the compounds with trans -vicinal phenyl groups. In the latter, the diaxial conformation is preferred ...
Axial substituents point straight up and down, less stable equatorial substituents in the plane of the molecule, more stable what happens to hydrogens when you flip a chair conformation axial hydrogens become equatorial and vice versa diaxial interactions steric interactions between axial substituentsde...
A two-step mechanism has been proposed that indicates that the catalytic process proceeds via trans-diaxial elimination of the 1α,2β hydrogen atoms from a 3-ketosteroid substrate [30]. Interaction of the C3 carbonyl group of a steroidal substrate with an electrophile promotes labilization of ...
(75%:25%; ΔG° = 0.42 kcal mol−1) with a preference for the diaxial conformer was found, due to the anomeric effect which also dominates the conformational equilibrium of 3-methoxy-1,2,4,5-tetroxane; the axial conformer was found, in agreement with the X-ray structure <1998AHC(...
亲电体 Diaxial?addition?双直键加成 Markovnikov’s?rube?马尔科夫尼科规则 Anti-Markovnikov?addition?反马氏加成 Michael?addition?迈克尔加成 Substitution?取代 Electrophilic?substitution?亲电取代 Addition-elimination?mechanism?加成消除机理 Electrophilic?aromatic?substitu-tion?亲电芳香取代 Electron?transfer?电子转移 ...
SN1 reaction has a carbocation as intermediate, so the nucleophile can attack from both sides (every carbocation is planar). Because of that, I think that the reaction occurs at the same velocity. It it had been a SN2 reaction, the cis would have reacted faster (because SN2 is a one ...