清华大学有机化学李艳梅老师第四章

Small rings
C3~C4
Medium rings C8~C12
Common rings C5~C7
Large rings
C13~
ห้องสมุดไป่ตู้
By the saturation 按不饱和度
CnH2n CnH2n-2 CnH2n-4
Cycloalkanes 环烷 Cyclo olefines 环烯 Cyclo alkynes 环炔
碳原子采取sp3杂化形式，正常键角应为约109.5度 3, to meet some special angles in the ring, the bonds have
to be bending; 为了满足平面正多边形的内角要求，成环的键必须向内或向 Mor外e “be屈nd挠in”g， “屈M挠o”re的a程ng度le越st大ra，in体系越不稳定。
By the number of the rings 按环的数目
Monocyclic compounds 单环 Polyring compounds 多环
桥头碳
螺原子
Spiro rings 螺环
两环之间共用一个 碳原子
Fused ring 稠环
Bridged ring 桥环
两环之间共用一根共 两环之间共用两个
A history
Year 1883
Name of scientist Baeyer
1890 H.Sachse 1915-1918 W.M.Mohr
1920
1943 O.Hassel
1950 D.Barton
Point of view
Assumes that six carbon atoms are on the same plane Two conformations may exist
3）书写：先写环数
方括号内沿着编号方向写出每个环中除桥头碳原子
8 7 12 3
外的每个环的碳原子数 数字之间用圆点隔开 最后写出包括桥头碳原子在内碳原子数的烷烃名称
65 4
bicyclo[3.2.1]octane
二环[3.2.1]辛烷
注意：有两个桥头碳可 供选择
2,7,7-trimethylbicyclo[2.2.1]heptane
Chair model and boat model
Cyclohexane was proved to be nonplanar experimentally Chair model is most stable (electron diffraction method) Conformation analysis of cyclohexane
4.1 Classification, Isomerization and no4m.1e.n1clCaltausrseification
4.1.2 Isomerism
4.1.3 Nomenclature
4.1.1 Classification
By the size of the ring 按环的大小
ChCyaclpoatlkeanres4 第四章 环烷烃
Organic Chemistry A (1) By Prof. Li Yan-Mei Tsinghua University
Content
4.1 Classification, Isomerization and nomenclature 4.2 Structure of cycloalkanes 4.3 Physical properties & spectrum data 4.4 Chemical properties 4.5 Preparation (learn on your own)
3-cyclohexylhexane 3-环己基己烷
3, When two rings are connected 两环相连时
Cyclopropylcyclohexane Cyclopropylcyclopropane
环丙基环己烷
环丙基环丙烷
4, Cis and trans isomerism:
CH3
tricyclic[3.2.2.12.7]dacane
Fused ring
naphthalene Endo/exa
Hydrogenated naphthalene
区别：母体！
H OH endo
OH H exa
4.2 Structure of cycloalkanes
4.2.1 Baeyer’s strain theory 4.2.2 Heat of combustion for
C
C
C
105.5o
C
C
C
角张力： 109.50-105.50=40
Bent Bond （弯曲键、香蕉键）
A nonplanar conformation 非平面构象
也存在弯曲键 111.50
角张力：111.50－109.50 = 20
H
4
H
H
H3 2H
H
1H
H
H H
H H
H
H H
H
蝴蝶状
蝴蝶式
部分交叉式 扭转张力较小
Decide the serial number 编号：从主桥头碳开始；从最长桥开始
Naming the compound
7
书写（注意与非主桥相连的桥需注明所连桥的编号） 4
5
3
1
6
2
Tricyclic[2.2.1.02.6]heptane
思考：
1
8
2
9
7
10
3
6
5 4
Tricyclic[3.2.2.12.7]decane
spiro[5.5]undecane 螺[5.5]十一烷
4-methylspiro[2.4]heptane 4-甲基[2.4]庚烷
2, Bridged-ring alkane and fused-ring alkane 桥环烃和稠环烃
1）选母体：根据成环的总碳原子数及环数，称为“n环某烷”。
2）编号：从桥头碳开始；从最长桥开始。
Higher energy
Less stability
60o
90o
108o
120o
129o
Most stable?
可解释一些体系的稳定性特点，但还有一些体系无法解释。
4.2.2 Heat of combustion for cycloalkane
n
Heat of
combustion 697 686 664
methylcyclopentane 甲基环戊烷
1-e thy l- 3- me thy lc yc lop ent ane
1-甲基-3-乙基环戊烷
2-ethyl-4-methyl-1propy lc yc loh ept ane
4-甲基-3-乙基-1-丙基环己烷
2, When the side chain is complicate or difficult to name: 当支链较复杂或不易命名时，以环烷基为取代基
价键（共用两个直接 不直接相连的碳原
相连的碳原子）
子
几环？
To define the number of the rings: The number of cutting you need to get a chain molecule out of a poly ring compound
将桥（稠）环烃变为链状化合物时需要断裂的碳链 数。如需断裂两次，则为二环化合物，断裂三次则 为三环化合物。
W.H.Perkin synthesized C3, C4, and identified the relative reactivity: double bond > C3 > C4 ,while C5 and C6 rings are relatively more stable.
A.von.Baeyer put forward the strain theory
CH3
H
H
CH3
CH3 H
H CH3
CH3
CH3
Cis-1,4-dimethylcyclohexane
CH3
Trans-1,4-dimethylcyclohexane
CH3 CH3
CH3 How to name this compound ?
4.1.3.2 Polyring alkane 多环烷烃
4.2.1 Baeyer’s strain theory Bayer’s张力学说
Assumption: 1, carbon atoms in the ring are on the same plane;
成环的碳原子均在同一同面上，且呈正多边形 2, carbon atoms are sp3 carbon atoms;
4
H 2C
H 2C 3
H H
1
2H H
6.3kJ/mol higher
全重叠式
2.5kJ/mol
envelop structure
信封式
half-chair structure
半椅式
如果：
具有多组全重叠式
Large ring 多于13个碳原子的环体系中，分子链一般呈皱折形
Strain energy in cycloalkanes
1, Spiro cycloalkanes 螺环烃
1）选母体：根据成环的总碳原子数，称为“螺某烷”。
2）编号：从小环开始；从第一个非螺原子开始。
3）书写：先写词头“螺”
方括号内沿着编号方向写出每个环中除螺原子