Reaction and mechanism types
| English | Chinese | Pinyin |
|---|---|---|
| curly arrow | 弯箭头 | wān jiàn tóu |
| addition | 加成 | jiā chéng |
| substitution | 取代 | qǔ dài |
| elimination | 消去 | xiāo qù |
| hydrolysis | 水解 | shuǐ jiě |
| condensation | 缩合 | suō hé |
| initiation | 引发 | yǐn fā |
| propagation | 增长 | zēng zhǎng |
| termination | 终止 | zhōng zhǐ |
How reactions actually happen
- Organic reactions fall into a few named types.
- Mechanisms show, step by step, how the electrons move.
- A curly arrow 弯箭头 tracks each electron pair.
Organic reaction type lab
Classify reaction examples by the pattern of bonds changing.
A species that is attracted to an electron-poor site and donates a pair of electrons is a:
Nucleophiles donate an electron pair.
Types of reaction
| Reaction | What happens |
|---|---|
| addition 加成 | two molecules join into one |
| substitution 取代 | one atom/group is swapped for another |
| elimination 消去 | a small molecule is removed, making a double bond |
| hydrolysis 水解 | a molecule is split apart by water |
| condensation 缩合 | two molecules join, losing a small molecule (e.g. water) |
- For organic redox, $[\text{O}]$ = one oxygen from an oxidising agent, $[\text{H}]$ = one hydrogen from a reducing agent.
The same molecule shown as molecular, structural, displayed and skeletal formula
Match each reaction type to what happens.
Addition joins; substitution swaps; elimination removes a small molecule to form a double bond.
In an addition reaction:
Addition combines two molecules into a single product (e.g. across a C=C bond).
Types of mechanism
- A free-radical reaction has three steps: initiation 引发 (radicals made), propagation 增长 (radicals react, make new radicals), termination 终止 (radicals join, chain stops).
- Main mechanisms: free-radical substitution (alkanes), electrophilic addition (alkenes), nucleophilic substitution (halogenoalkanes), nucleophilic addition (carbonyls).
- A curly arrow shows a pair of electrons moving (from a bond or a lone pair).
Put the steps of a free-radical mechanism in order.
Initiation makes radicals, propagation keeps the chain going, termination joins radicals to stop it.
In a mechanism, a curly arrow shows:
A curly arrow represents the movement of a pair of electrons, starting from a bond or a lone pair.
Classifying a reaction
- Identify the type — addition, substitution, elimination — and the attacking species.
- Nucleophiles attack electron-poor carbons; electrophiles attack electron-rich sites.
You've got it
- reaction types: addition, substitution, elimination, hydrolysis, condensation; $[\text{O}]$ / $[\text{H}]$ for redox
- a free-radical mechanism runs initiation → propagation → termination
- main mechanisms: free-radical substitution, electrophilic addition, nucleophilic substitution/addition
- a curly arrow = a moving electron pair