📚 Edexcel A-Level Chemistry Combined-068: Organic Chemistry I | 爱德思A-Level化学 Combined-068:有机化学I
This revision guide covers the core ideas in Edexcel A-Level Chemistry Topic 6: Organic Chemistry I. You will learn how to name organic molecules, identify functional groups, explain structure and isomerism, and write mechanisms for key reactions. The focus is on exam-ready understanding: definitions, equations, conditions and curly-arrow mechanisms.
本复习指南涵盖爱德思A-Level化学第6专题:有机化学I的核心内容。你将学习如何命名有机分子、识别官能团、解释结构与异构现象,并书写关键反应的反应机理。重点在于备考所需的理解:定义、方程式、条件以及卷箭头机理。
1. Homologous Series and Functional Groups | 同系列与官能团
A homologous series is a family of organic compounds with the same general formula, similar chemical properties and a gradual trend in physical properties. The functional group is the atom or group of atoms that gives the series its characteristic reactions.
同系列是一类具有相同通式、相似化学性质以及物理性质递变规律的有机化合物家族。官能团是赋予该系列特征反应的原子或原子团。
| Class 类别 | Functional group 官能团 | Suffix/prefix 后缀/前缀 | Example 示例 |
|---|---|---|---|
| Alkane 烷烃 | C–C, C–H | -ane | CH₄ |
| Alkene 烯烃 | C=C | -ene | CH₂=CH₂ |
| Halogenoalkane 卤代烃 | –X (F, Cl, Br, I) | halo- | CH₃CH₂Br |
| Alcohol 醇 | –OH | -ol | C₂H₅OH |
| Aldehyde 醛 | –CHO | -al | CH₃CHO |
| Ketone 酮 | C=O | -one | CH₃COCH₃ |
| Carboxylic acid 羧酸 | –COOH | -oic acid | CH₃COOH |
| Nitrile 腈 | –C≡N | -nitrile | CH₃CN |
| Amine 胺 | –NH₂ | -amine | CH₃NH₂ |
You must be able to recognise these functional groups from structural, displayed and skeletal formulas.
你必须能够从结构式、展示式以及骨架式中识别这些官能团。
2. Nomenclature of Organic Compounds | 有机化合物的命名
IUPAC naming follows a clear set of rules. Identify the longest continuous carbon chain to give the stem, number the chain so the functional group or substituents get the lowest possible numbers, and place substituents in alphabetical order.
IUPAC命名遵循一套明确规则。找出最长的连续碳链作为主链,对链进行编号,使官能团或取代基获得尽可能小的位次,并按字母顺序排列取代基。
- Stem 主链: meth-, eth-, prop-, but-, pent-, hex-
- Example 示例: CH₃CH(CH₃)CH₂CH₃ = 2-methylbutane
- Di/tri 二/三: CH₃CH₂CH(Cl)₂ = 1,1-dichloropropane
- Functional group suffix 官能团后缀: propan-1-ol, ethanoic acid
Always write commas between numbers and hyphens between a number and a word. Do not leave gaps in exam answers.
数字之间用逗号,数字与文字之间用连字符。考试作答时不要留空格。
3. Structural Isomerism | 结构异构
Structural isomers have the same molecular formula but different structural formulas. There are three main types: chain isomerism, position isomerism and functional group isomerism.
结构异构体具有相同的分子式,但结构式不同。主要有三种类型:碳链异构、位置异构和官能团异构。
- Chain isomers differ in the arrangement of the carbon skeleton, such as butane and 2-methylpropane.
- Position isomers have the same functional group at different positions, such as propan-1-ol and propan-2-ol.
- Functional group isomers have different functional groups, such as propanal and propanone.
碳链异构体碳骨架排列不同,如丁烷和2-甲基丙烷;位置异构体官能团位置不同,如丙-1-醇和丙-2-醇;官能团异构体官能团种类不同,如丙醛和丙酮。
Drawing all possible structural isomers for a given formula is a common exam skill. Always check for repeated structures that may be identical after rotation.
绘制给定分子式所有可能的结构异构体是常见的考试技能。务必检查是否有旋转后完全相同的重复结构。
4. Stereoisomerism: E/Z Isomerism | 立体异构:E/Z异构
Stereoisomers have the same structural formula but a different arrangement of atoms in space. E/Z isomerism occurs in alkenes because rotation around the C=C double bond is restricted.
立体异构体具有相同的结构式,但原子在空间的排列方式不同。E/Z异构现象出现在烯烃中,因为C=C双键周围的旋转受到限制。
For E/Z assignment, use the Cahn-Ingold-Prelog priority rules: the atom with the higher atomic number bonded to the double-bond carbon has higher priority. If the higher-priority groups are on opposite sides, the isomer is E; if they are on the same side, it is Z.
E/Z标记采用Cahn-Ingold-Prelog优先规则:与双键碳原子相连的原子序数越高,优先性越高。若高优先基团位于双键两侧,则为E型;若在同侧,则为Z型。
Example 示例: but-2-ene CH₃CH=CHCH₃ has E and Z forms because each double-bond carbon has a CH₃ group and an H atom attached.
示例:丁-2-烯 CH₃CH=CHCH₃ 具有E型和Z型,因为每个双键碳原子上都连接一个CH₃基团和一个H原子。
5. Alkanes: Combustion and Free-Radical Substitution | 烷烃:燃烧与自由基取代
Alkanes are relatively unreactive because C–C and C–H sigma bonds are strong and non-polar. They undergo complete combustion in excess oxygen to produce carbon dioxide and water.
烷烃相对不活泼,因为C–C和C–H σ键较强且非极性。它们在过量氧气中发生完全燃烧,生成二氧化碳和水。
CH₄ + 2O₂ → CO₂ + 2H₂O
In limited oxygen, incomplete combustion produces carbon monoxide or carbon. Carbon monoxide is toxic because it binds permanently to haemoglobin.
在氧气不足时,不完全燃烧会产生一氧化碳或碳。一氧化碳有毒,因为它与血红蛋白不可逆结合。
Alkanes also react with chlorine or bromine in ultraviolet light by free-radical substitution. The mechanism has three stages: initiation, propagation and termination.
烷烃还能在紫外光下与氯或溴发生自由基取代反应。该机理包括三个阶段:链引发、链增长和链终止。
- Initiation: Cl₂ → 2Cl• (UV light breaks the covalent bond)
- Propagation: CH₄ + Cl• → CH₃• + HCl; CH₃• + Cl₂ → CH₃Cl + Cl•
- Termination: Cl• + Cl• → Cl₂; CH₃• + Cl• → CH₃Cl; CH₃• + CH₃• → C₂H₆
链引发:Cl₂ → 2Cl•(紫外光打断共价键);链增长:CH₄ + Cl• → CH₃• + HCl;CH₃• + Cl₂ → CH₃Cl + Cl•;链终止:Cl• + Cl• → Cl₂;CH₃• + Cl• → CH₃Cl;CH₃• + CH₃• → C₂H₆。
Curly arrows are not required for free-radical mechanisms, but you must show unpaired electrons and the movement of single electrons using half
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