第2章 饱和碳氢化合物

3、开链烷烃的命名
（2）取代基数目一样多时，以侧链位次最 低的链为主链
CH3 CH3 7 6 5 4 3 2 1 CH3CH2CHCHCH2CHCH3 7 6 5 4 3CHCH3 CH2CH3 2 1 或 or 2,5-二甲基-4-仲丁基庚烷 2,5-二甲基-4-(1-甲基丙基)庚烷 4-(sec-butyl)-2,5-dimethylheptane 2,5-dimethyl-4-(1-methlpropyl)heptane
CH3CH2CH2CH2CH3 CH3CHCH2CH3 CH3 戊烷 pentane 异戊烷 isopentane
3、开链烷烃的命名
构造异构体（constitutional isomers）——这种分 子式相同但分子内原子的连接顺序不同的异构体
普通命名法
1. 对于碳数为C1 ~ C10的烷烃——甲、乙、丙、丁、戊 、己、庚、辛、壬、癸表示碳数，称为“某烷” 2. 对于碳数> C10的烷烃——直接用中文数字表示碳数 3. 对于构造异构体，则使用“正”、“异”、“新”等表示
单环环烷烃的结构通式： CnH2n
环丙烷 cyclopropane
环丁烷 cyclobutane
环戊烷 cyclopentane
C3 H6
C4H8
C5H10
2、通式与不饱和度（环的数目）
不饱和度 — 分子组成的氢原子数目与理论上最 大可能数目之差的情况
Saturated Hydrocarbons: CnH2n+2 For a formula: CnHm Degree of unsaturated Ω = (2n+2-m)/2 If it is a cycloalkane, the degree of unsaturated equals to the number of ring
CH2CH3 CH3 CH3CH2CCH2CH2CHCHCH2CH2CH3 CH2CH3 CH2CH3 3,3,6-triethyl-7-methyldecane CH3 CH3CH2CH2CHCH2CH2CHCH3 CHCH3 CH3 5-isopropyl-2-methlyoctane
3、开链烷烃的命名
3、开链烷烃的命名
普通命名法的局限
CH3CH2CH2CH2CH2CH3 hexane CH3CHCH2CH2CH3 CH3 isohexane CH3CH2CHCH2CH3 CH3 none CH3 CH3—C—CH2 CH3 CH3 neohexane CH3CH—CHCH3 CH3 CH3 none
CH3CH2CH2CHCH2CH2CH3 1 2 CHCH3 CH3 3-isopropylheptane or 3-(1-methylethyl)heptane CH3CH2CH2CHCH2CH2CH3 1 2 3 CH2CHCH3 CH3 4-isobutylheptane or 4-(2-methylpropyl)heptane
3、开链烷烃的命名
次序规则:
(1) 原子序数大的为“较优”基团 (2) 第一原子相同，按原子序数大小顺序比较 第二原
子（Cl, H, H > O, O, C；Cl, O, H > Cl, C, C） (3) 含有双键和叁键的基团，可以认为连有两个或三 个相同原子
O C H 视为
H C O (O)(C)
2、通式与不饱和度（环的数目）
烷烃的结构通式： CnH2n+2
名称 甲烷 乙烷 丙烷 正丁烷 异丁烷 碳数 1 2 3 4 4 分子式 CH4 C2H6 C3H8 C4H10 C4H10 结构简式 CH4 CH3CH3 CH3CH2CH3 CH3CH2CH2CH3 (CH3)2CHCH3
2、通式与不饱和度（环的数目）
3、开链烷烃的命名
(3）在较短的侧链中，具有碳原子数目最多 的链 H3C H3C CH3 CH2CH3
H3CH2CHCH2CHCH2C 7 CH2CHCH2CHCH2CH3 13 12 11 10 9 8 C 6 5 4 3 2 1 H3CH2CHCH2CHCH2C H3C H3C CH2CHCH2CHCH2CH3 CH3 CH3
CH3 CH3 3o 2o 2o 1o H3C C4oCH2CHCH2CH2CH3 H3C C3o CH3 CH3 CH3 叔丁基 tert-butyl
1o 2o 1o
Байду номын сангаас
CH3CH2CH CH3 仲丁基 sec-butyl
CH3CH2CH2CH2 丁基 butyl
3、开链烷烃的命名
系统命名法(IUPAC Rules) IUPAC: International Union of Pure and Applied Chemistry COOH (S)-2-羟基丙酸
3、开链烷烃的命名
1 2 3 4 5 6 7 8 9
CH3CH2CHCH2CHCH2CH2CH2CH3 3 2 1 CH2 CHCH2CH3 CH3 CH2CH3
3-乙基-5-(1-乙基丙基)壬烷 3-ethyl-5-(1-ethylpropyl)nonane
4、环烷烃的命名
1. In the case of a cycloalkane with an attached alkyl substituent, the ring is the parent hydrcarbon unless the substituent has more carbons than the ring.
H3C
C
H OH
构型 取代基 母体名
3、开链烷烃的命名
直链烷烃同普通命名法，取消“正”字 支链烷烃： 1. Determine the number of carbon in the longest continuous carbon chain----This chain is called the parent hydrocarbon. 2. Number the chain so that the substituent gets the lowest possible number.
4. If the same substituent number are obtained in both directions, the first cited group received the lower number. 中文中则以基团的优先次序决定，给较优基团以 大编号。 CH3 3-ethyl-5-methylheptane CH3CH2CHCH2CHCH2CH3 3-甲基-5-乙基庚烷 CH2CH3 not Cl CH3CHCHCH3 Br 5-ethyl-3-methylheptane 2-bromo-3-chlorobutane 2-氯-3-溴丁烷 not 3-bromo-2-chlorobutane
3、开链烷烃的命名
烷基（Alkyl）——烷烃分子中从形式上消除一个氢的部 分，通常用 R- 表示，英文 用 “ yl ” 替代 “ ane ”
Methane —— Methyl Ethane —— Ethyl n-Propane —— n-Propyl CH3CH2CH3 n-Butane —— isopropyl n-Butyl CH3CH3CH2CH3CH2CH2(CH3)2CHCH3CH2CH2CH2CH3CH2CHCH3 (CH3)2CHCH2(CH3)3CMe Et n-Pro i-Pro n-Bu sec-Bu i-Bu tert-Bu
H C C C
视为
H C C C (C)(C)
3、开链烷烃的命名
常见烷基的次序举例：
CH3 CHCH3 >
异丙基 isopropyl
CH3 C CH3 CH3 叔丁基 tert-butyl
CH3 CH2 C CH3 > CH3 新戊基 neopentyl
CH3 CH2CHCH3
异丁基 isobutyl
CH3 CH2CHCH3
异丁基 isobutyl
>
CH3 CHCH2CH3 >
仲丁基 sec-butyl
>
CH2(CH2)2CH3
正丁基 n-butyl
3、开链烷烃的命名
5. 如果具有不止一条可选择的等长的碳链：
（1）以取代基数目最多的碳链为主链。
CH3CH2CHCH2CH3 正确名称为： 2-甲基-3-乙基戊烷 3 2 1 4 5 3-ethyl-2-methylpentane 2CHCH3 而不是： 3-异丙基戊烷 1CH3 not： 3-isopropylpentane
（各侧链数分别为111288和111189） 3-ethyl- 5,9,11-trimethyl-7,7-di(2,4dimethylhexyl)tridecane
3、开链烷烃的命名
6. If there are some complex substituents, we can use the similar method to name the substituents.
CH3CH2CH2CH3 sec-Butyl iso-Butane—— iso-Butyl (CH3)2CHCH3 tert-Butyl
3、开链烷烃的命名
烷烃中碳和氢的种类 Primary（1º）, secondary（ 2º ）, tertiary （ 3º ）, quaternary C（ 4º ）, but only primary, secondary, tertiary H
CH3CH2CH2CH2CHCH2CH3 5 1 2 3 4 CH2CH3
6 7
7
6
5
4
3
2
1
母体名：庚烷 heptane
全名：3-乙基庚烷（3- ethylheptane）
3、开链烷烃的命名
3. Cite the name of the alkyl substituent before the parent hydrocarbon. —— A number and a word are separated by a hyphen; numbers are separated by a comma. di, tri, tetra is used to express the number of the same substituents
第二章
饱和碳氢化合物 Saturated Hydrocarbons
第二章重点讲解问题
一、饱和碳氢化合物（烷烃、环烷烃）的命名 二、饱和碳氢化合物的构象与构象分析 三、碳氢化合物的稳定性与拜尔的环张力学说 四、饱和碳氢化合物的物理性质
1、 Representing Molecules
Molecular formula CH4
3、开链烷烃的命名
CH4 CH3CH3 Methane Ethane
CH3CH2CH2CH3 丁烷 butane CH3CHCH3 CH3 异丁烷 isobutane CH3 H3C C CH3 CH3 新戊烷 neopentane
CH3CH2CH3 Propane
CH3CH CH3 “异”基结构单元 "iso" CH3 H3C C CH2 CH3 “新”基结构单元 "neo"
1 2 3 4 5 6 7
CH3CHCH2CH2CHCH2CH3 CH3 CH3
2,5-二甲基庚烷 2,5-dimethylheptane
3、开链烷烃的命名
And list substituents in alphabetical order. —— “di, tri, tetra, sec, and tert” are ignored in alphabetizing. “iso, neo, and cyclo” are not ignored in alphabetizing.
a Lewis dot structure H H : C :H H
:
Kekulé structure H H C H H
a Sawhorse representation H H C H H
a hatched line ------ behind the plane
:
a solid wedge ------ in front of the plane
5 4 3
(two substituents) (one substituent)
CH3 CH3CH2CH CHCH CHCH3 CH3 CH2 CH3 CH2CH3
2,3,5trimethyl-4-propylheptane not 3-methyl-4-(1,2dimethylpropyl)heptane