烷烃和环烷烃的构象异构 2 Butane H3C CH H3c H H CH H D syn eclipsed gauche conformer anti conforme yn eclipsed Steric Strain aa steric effect e van der Waals repulsion of groups that are close to each other一、烷烃和环烷烃的构象异构 2. Butane Steric Strain ---- a steric effect van der Waals repulsion of groups that are close to each other H H CH3 H3C H H C H H3C H H3C H H C' H3C H H H3C H H B' H3C H H H H CH3 A syn eclipsed H H CH3 H3C H H B gauche conformer H CH3 H H3C H H D anti conformer H3C H H H H CH3 A syn eclipsed