清华大学有机化学李艳梅老师第四章

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
百度文库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。
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。
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
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
659
662
658
per CH2
kJ/mol
Do not fit the strain theory!
影响环体系稳定性的主要因素：
角张力（Baeyer 张力） 扭转张力 范氏力
4.2.3 Current opinions
2 3
1
3
CH2
H
H
12
HH
扭转张力： 三组H－C－C 均处于全重叠式
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
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
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
Small rings
C3~C4
Medium rings C8~C12
Common rings C5~C7
Large rings
C13~
By the saturation 按不饱和度
CnH2n CnH2n-2 CnH2n-4
Cycloalkanes 环烷 Cyclo olefines 环烯 Cyclo alkynes 环炔
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
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
环的大小及侧链长短与位置变化
4.1.3 Nomenclature 命名
4.1.3.1 Monocyclic alkane 单环烷烃
1, When the side chain is not very complicate: 当支链不复杂时，以环烷烃为母体
1,2 -dimethy lcyc lo pent ane 1,2-二甲基环戊烷
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
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
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
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。
Name
C3 C4 C5 C6 C7~C12 C12~
Angle strain Great Great Slight No
Medium No
Twist strain Medium Medium Medium No Medium No
Van de waals No No No No
Great No
4.2.4 Conformations 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
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;
Some interesting bridging compounds
Cubane 立方烷
篮烷
Primane 棱烷
Diamentane 金刚烷
4.1.2 Isomerism Constitutional isomers are derivated from the change of size of rings and length of sCid5eHc10hains
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
2,7,7-三甲基二环[2.2.1]庚烷
bicyclo[1.1.0]butane
二环[1.2.0]丁烷
For polycyclic compound as following 多元环
Deciding the main ring 选“主环”：最大的环
Choosing the main bridged carbon 选“主桥头碳”：主环与非主环的最长桥共用的桥头碳
3
4 10
9
螺[4.5]癸烷
“小原则”：在不违背螺环烃命名的“大”原则基础上，在编号 时应尽可能令取代基的位号最小。
16 7
2
5
8
3
4 10 9
1-甲基螺[4.5]癸烷
思考！
16 7 2
8 35
4 10 9
spiro[4.5]decane 螺[4.5]癸烷
1 67 2
8 35
4 10 9
6-methylspiro[4.5]decane 6-甲基[4.5]癸烷
cycloalkane 4.2.3 Current opinions 4.2.4 Conformations of cyclohexane 4.2.5 Configuration of decalin
Before 1880 1883 1885
Only penta rings and hexa rings were found. It was regarded that rings smaller than penta rings and bigger than hexa rings do not exist, or are not stable.
Chair model and boat model
Cyclohexane was proved to be nonplanar experimentally Chair model is most stable (electron diffraction method) Conformation analysis of cyclohexane
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
16 7
1
2
5
外的每个环的碳原子数 数字之间用圆点隔开
8
最后写出包括螺原子在内碳原子数的烷烃名称
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)