📚 AS Organic Chemistry Core Concepts | AS 有机化学核心概念
This revision guide covers the core organic chemistry topics tested in the AS-level Oxford AQA International A-level Chemistry specification.
本复习指南涵盖牛津 AQA 国际 A-level 化学 AS 阶段有机化学的核心考点。
It includes functional groups, nomenclature, isomerism, reaction mechanisms and the key reactions of alkanes, alkenes, alcohols and haloalkanes.
内容包括官能团、命名法、异构现象、反应机理以及烷烃、烯烃、醇和卤代烷的关键反应。
1. Functional Groups and Homologous Series | 官能团与同系物
A functional group is the atom or group of atoms that gives a homologous series its characteristic chemical reactions.
官能团是赋予同系物特征化学反应的原子或原子团。
A homologous series is a family of compounds with the same functional group, each member differing by a CH₂ unit.
同系物是一类具有相同官能团的化合物，相邻成员相差一个 CH₂ 单元。
| Homologous series 同系物 | Functional group 官能团 | General formula 通式 |
|---|---|---|
| Alkane 烷烃 | C–C single bonds only 仅 C–C 单键 | CₙH₂ₙ₊₂ |
| Alkene 烯烃 | C=C double bond C=C 双键 | CₙH₂ₙ |
| Alcohol 醇 | –OH hydroxyl group –OH 羟基 | CₙH₂ₙ₊₁OH |
| Haloalkane 卤代烷 | –X halogen atom –X 卤原子 | CₙH₂ₙ₊₁X |
Physical properties such as boiling point show a gradual trend as molar mass increases, but chemical properties are controlled by the functional group.
随着摩尔质量增加，沸点等物理性质呈现渐变趋势，但化学性质由官能团决定。
2. IUPAC Nomenclature | IUPAC 命名法
IUPAC names are built from a prefix, a stem indicating the longest carbon chain, and a suffix for the principal functional group.
IUPAC 名称由前缀、表示最长碳链的主链名称以及主官能团后缀组成。
- Chain length prefixes 主链长度前缀: meth- 甲, eth- 乙, prop- 丙, but- 丁, pent- 戊, hex- 己
- Suffixes 后缀: -ane for alkane 烷烃, -ene for alkene 烯烃, -ol for alcohol 醇
- Halogen prefixes 卤素前缀: fluoro- 氟, chloro- 氯, bromo- 溴, iodo- 碘
Number the chain from the end that gives the functional group or substituent the lowest possible locant.
给碳链编号时，从使官能团或取代基位次最小的一端开始。
For example, CH₃CH(OH)CH₂CH₃ is butan-2-ol, not butan-3-ol.
例如，CH₃CH(OH)CH₂CH₃ 是丁-2-醇，而不是丁-3-醇。
When two or more identical substituents are present, use prefixes such as di-, tri- and tetra-.
当存在两个或多个相同取代基时，使用二、三、四等前缀。
3. Structural Isomerism | 结构异构
Structural isomers have the same molecular formula but different structural arrangements of atoms.
结构异构体具有相同的分子式，但原子连接方式不同。
- Chain isomerism 链异构: different carbon skeleton, e.g. butane and methylpropane 丁烷和甲基丙烷.
- Position isomerism 位置异构: functional group at different position, e.g. propan-1-ol and propan-2-ol 丙-1-醇和丙-2-醇.
- Functional group isomerism 官能团异构: different functional group, e.g. ethanol and methoxymethane, both C₂H₆O 乙醇和甲醚，均为 C₂H₆O.
Isomers often have different physical properties because molecular shape and intermolecular forces differ.
由于分子形状和分子间作用力不同，异构体的物理性质通常不同。
Chemical properties may also differ significantly when the functional group changes.
当官能团改变时，化学性质也可能显著不同。
4. Stereoisomerism: E/Z Isomers | 立体异构：E/Z 异构
Stereoisomers have the same structural formula but a different spatial arrangement of atoms.
立体异构体具有相同的结构式，但原子在空间排列不同。
E/Z isomerism occurs in alkenes because rotation about the C=C double bond is restricted.
由于 C=C 双键不能自由旋转，烯烃存在 E/Z 异构。
A molecule shows E/Z isomerism when each carbon of the double bond carries two different groups.
当双键两端的每个碳原子上都连有两个不同基团时，分子存在 E/Z 异构。
Use the Cahn-Ingold-Prelog priority rules: a higher atomic number gives a higher priority.
使用 Cahn-Ingold-Prelog 优先规则：原子序数越大，优先级别越高。
If the two higher-priority groups are on opposite sides of the double bond, the
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