0. The different arrangements of atoms caused by rotation about a single bond are called conformations, and a specific conformation is called a conformer(conformation isomer) a Unlike constitutional isomers, though different conformers can't usually be ①D isolated because they interconvert too rapl ⑨D
Organic Chemistry Organic Chemistry Xiamen Xiamen University University The different arrangements of atoms caused by rotation about a single bond are called conformations, and a specific conformation is called a conformer (conformation isomer). Unlike constitutional isomers, though, different conformers can’t usually be isolated because they interconvert too rapidly
乙烷的构象 可|■构象式的表达方式: Newman投影式( Newman projections) 锯架式( Sawhorse representations) n伞式 H H、H H、 H H H H H H H H H H H H
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 乙烷的构象 构象式的表达方式： Newman 投影式(Newman projections) 锯架式( Sawhorse representations) 伞式 H H H H H H H H H H H H H H H H H H
重叠式构象与交叉式构象 H H 600H H H H HH H 重叠式构象 交叉式构象 刘 能量差12.1kJmo1
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 重叠式构象与交叉式构象 H H H H H H H H H H H H 重叠式构象 交叉式构象 60 O 能量差 12.1 kJ·mol-1
重叠式与交叉式构象的能量分析 2.29A H H H 键长:C—H1.07,C-C1.54A 键角:∠HCH1095° 重叠式两个H之间距离:2.29A 引氢原子半径:m=12A
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 重叠式与交叉式构象的能量分析 H H H H H H 2.29 A 键长： C —H 1.07, C —C 1.54 A 键角：∠HCH 109.5 ° 重叠式两个 H之间距离：2.29 A 氢原子半径： γ H = 1.2 A
乙烷不同构象的能量曲线图 重叠式构象 E 交叉式构象 H H H CHH H HH H H H H H H H H ①D 12.1 kJ/ mol ⑨D 60° 120° 180 248旋转角度
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 乙烷不同构象的能量曲线图 60 1 20 180 240 E H H H H H H H H H H H H 重叠式构 象 交叉式构象 H H H H H H H H H H H H 12.1 k J / mol 旋转角 度