Phenol · 苯酚
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| phenol/ˈfenɒl/ | 苯酚 | běn fēn |
| phenylamine/ˌfiːˈnaɪləmiːn/ | 苯胺 | běn àn |
| diazonium salt/ˌdaɪəˈzəʊnɪəm sɒlt/ | 重氮盐 | zhòng dàn yán |
| phenoxide/feˈnɒksaɪd/ | 苯氧 | běn yǎng |
| bromination/ˌbrəʊmɪˈneɪʃn/ | 溴化 | xiù huà |
The ring that's acidic
- Phenol 苯酚 has an –OH joined directly to a benzene ring.
- This changes the chemistry of both the –OH group and the ring.
- It is more acidic than an alcohol, and its ring is more reactive than benzene's.
酸性的环
- 苯酚(phenol)有一个 –OH 直接连接到一个苯环。
- 这改变了 –OH 基团和环两者的化学。
- 它比一个醇更酸,它的环比苯的更活泼。
Phenol reaction lab · 苯酚反应实验室
Classify phenol reactions by the role of the aromatic OH group. · 按芳香 OH 基团的作用分类苯酚反应。
Phenol is: · 苯酚是:
The –OH is bonded straight to the aromatic ring, changing both the –OH and the ring chemistry. · –OH 直接键合到芳香环,改变 –OH 和环两者的化学。
Phenol is a weak acid that reacts with sodium hydroxide. · 苯酚是一个与氢氧化钠反应的弱酸。
The –OH on the ring is more acidic than in an alcohol. · 环上的 –OH 比一个醇中的更酸。
Making and reacting
- Make it: cool phenylamine 苯胺 with $\text{NaNO}_2$ + dilute acid (below 10 °C) → a diazonium salt 重氮盐; warm with water → phenol.
- Reactions:
- with NaOH(aq) → sodium phenoxide 苯氧 + water (alcohols don't react with NaOH — phenol is more acidic).
- with sodium → sodium phenoxide + hydrogen.
- bromination 溴化 with bromine water (RT, no catalyst) → 2,4,6-tribromophenol (white precipitate).
Phenol is acidic because the phenoxide charge spreads into the ring
制造和反应
- 制造它:把苯胺(phenylamine)与 $\text{NaNO}_2$ + 稀酸冷却(低于 10 °C)→ 一个重氮盐;与水加热 → 苯酚。
- 反应:
- 与 NaOH(aq) → 苯酚钠 + 水(醇不与 NaOH 反应——苯酚更酸)。
- 与钠 → 苯酚钠 + 氢。
- 用溴水溴化(室温,无催化剂)→ 2,4,6-三溴苯酚(白色沉淀)。
苯酚是酸性的,因为苯氧离子的电荷扩散到环中
Unlike an ordinary alcohol, phenol reacts with NaOH(aq). This shows phenol is: · 与一个普通的醇不同,苯酚与 NaOH(aq) 反应。这显示苯酚是:
Phenol is acidic enough to react with NaOH, forming sodium phenoxide; alcohols are not. · 苯酚足够酸以与 NaOH 反应,形成苯酚钠;醇不是。
Phenol with bromine water at room temperature (no catalyst) gives: · 苯酚在室温下(无催化剂)与溴水给出:
The activated ring reacts readily, brominating positions 2, 4 and 6 to give a white precipitate. · 被活化的环容易反应,在位置 2、4 和 6 溴化以给出一个白色沉淀。
Match each term to its meaning. · 匹配每个术语和它的含义。
Each item links the term to its correct meaning. · 每一项把术语链接到它正确的含义。
Acidity and the activated ring
- Phenol loses $\text{H}^+$ to a phenoxide ion, stabilised because the charge spreads into the ring. So acidity is:
$$\text{ethanol} < \text{water} < \text{phenol}$$
- A lone pair on the oxygen is partly delocalised into the ring, making it electron-rich — so phenol reacts under milder conditions than benzene (no catalyst, dilute reagents, room temperature). The –OH directs to 2, 4, 6.
The activated ring lets phenol brominate in cold bromine water — no catalyst — to 2,4,6-tribromophenol
Carbolic soap contains phenol, once widely used as an antiseptic.
酸性和被活化的环
- 苯酚失去 $\text{H}^+$ 成一个苯氧离子,被稳定因为电荷扩散到环中。所以酸性是:
$$\text{ethanol} < \text{water} < \text{phenol}$$
- 氧上的一个孤对电子部分离域到环中,使它电子富集——所以苯酚在比苯更温和的条件下反应(无催化剂、稀试剂、室温)。–OH 定向到 2、4、6。
被活化的环让苯酚在冷溴水中溴化——无催化剂——成 2,4,6-三溴苯酚
石炭酸皂含有苯酚,曾广泛用作一种消毒剂。
The acidity order is: · 酸性顺序是:
Phenol is the most acidic of the three because the phenoxide charge is delocalised into the ring. · 苯酚是三者中最酸的,因为苯氧离子的电荷离域到环中。
Phenol's reactions
- Phenol reacts with sodium hydroxide (it is acidic) and with bromine water (the ring is activated).
- Bromine water decolourises and a white precipitate forms — no UV needed.
Phenol is a low-melting solid that turns pink as it oxidises in air.
苯酚的反应
- 苯酚与氢氧化钠反应(它是酸性的)并与溴水反应(环被活化)。
- 溴水褪色,一个白色沉淀形成——不需要紫外光。
苯酚是一个低熔点固体,在空气中氧化时变粉色。
You've got it
- phenol = –OH directly on a benzene ring
- it reacts with NaOH (more acidic than an alcohol); bromine water → 2,4,6-tribromophenol (white ppt, no catalyst)
- acidity: ethanol < water < phenol (phenoxide stabilised by the ring)
- the ring is activated (lone pair delocalised in), so phenol reacts under milder conditions than benzene
你掌握了
- 苯酚 = –OH 直接在一个苯环上
- 它与 NaOH 反应(比一个醇更酸);溴水 → 2,4,6-三溴苯酚(白色沉淀,无催化剂)
- 酸性:ethanol < water < phenol(苯氧离子被环稳定)
- 环被活化(孤对电子离域进入),所以苯酚在比苯更温和的条件下反应