部分氧化
乙醇 → 乙醛：查看反应物、产物、反应条件与来源依据，探索相关转化和合成路径。
- 试剂
- K2Cr2O7／稀 H2SO4
- 条件
- 控制加热；通过蒸馏及时移出醛
- 反应类别
- 部分氧化
- 方程式
- CH3CH2OH + [O] -> CH3CHO + H2O
概览
乙醇氧化为乙醛。
转化
- 方程式
- CH3CH2OH + [O] -> CH3CHO + H2O
- 试剂
- K2Cr2O7／稀 H2SO4
- 反应环境
- 控制加热；通过蒸馏及时移出醛
- 反应类别
- 部分氧化
- 机理
- 醇氧化
- Evidence level
- source-backed molecular example
参考步骤
Selective oxidation to ethanal
乙醇 → 乙醛
物料与用量
- 乙醇
- Acidified dichromate; use the cited method’s quantities
仪器装置
- Distillation apparatus
- Receiver
实验步骤
- Collect the volatile product by distillation as it forms to limit further oxidation.
- Record the oxidant colour change separately from the product observations.
后处理与分离
- Use the cited aldehyde test on a separate aliquot; compare an IR spectrum where available.
关键控制条件
- Record the orange-to-green change and analyse the distillate, which may contain water and alcohol.
- Control flammable vapour and segregate chromium-containing waste.
实验技术
Distillation setup
Rearrange the apparatus to collect a volatile product or fraction instead of returning condensate to the reaction flask.
装置设置
- Position the thermometer bulb at the entrance to the condenser so it measures vapour entering the condenser.
- Run cooling water into the lower condenser connection and out through the upper connection.
- Heat gradually and collect only the fraction specified by the cited boiling range or procedure.
操作检查
- Do not distil a flask to dryness.
- Use an electric heat source for flammable mixtures.
- Change from reflux to distillation only after heating has stopped and the apparatus has cooled enough to handle safely.
Infrared evidence for functional-group change
Use functional-group absorptions and the fingerprint pattern to test a proposed transformation.
装置设置
- Check sample identity, background and axis units before assigning absorptions.
- Compare the starting material and product: oxidation may introduce C=O while removing an alcohol O–H feature.
操作检查
- Water, solvent and unreacted substrate can contribute bands.
- A carbonyl band alone does not distinguish every aldehyde, ketone, acid and ester. Use reference data and complementary evidence; no simulated trace is a measurement.
底物范围
- 适用范围
- 乙醇；伯醇。
- 来源说明
- 六价铬试剂具有危险性；此教学记录不提供实验操作规程。继续氧化可生成乙酸。
相关反应
- Iodoform reaction: Ethanal → Triiodomethane 个产物
乙醛在碱性碘溶液中发生碘仿反应，生成三碘甲烷和甲酸盐。
- Iodoform reaction: Ethanol → Triiodomethane 个产物
乙醇被碱性碘溶液氧化并断裂，生成三碘甲烷和甲酸盐。
- Oxidation: Ethanol → Ethanoic acid
乙醇氧化为乙酸。
- Oxidation: Ethanal → Ethanoic acid
乙醛氧化为乙酸。
- Reduction: Ethanal → Ethanol
乙醛还原为乙醇。
- Esterification: Ethanol → Ethyl acetate
乙酸与乙醇可逆反应，形成乙酸乙酯和水。
- Acid hydrolysis: Ethyl acetate → Ethanol
乙酸乙酯与水可逆反应，形成乙酸和乙醇。
- Hydration: Ethene → Ethanol
乙烯通过水合生成乙醇。
- Dehydration: Ethanol → Ethene
乙醇通过脱水生成乙烯。
- Intermolecular dehydration: Ethanol → Diethyl ether
质子化使一个乙醇分子的羟基成为更易离去的基团。另一个乙醇分子的氧取代水，随后去质子化生成乙醚；更强的脱水条件则有利于生成乙烯。
- Hydrolysis: Bromoethane → Ethanol
氢氧根进攻与溴相连的饱和碳，同时 C-Br 键断裂。该伯底物的 SN2 路线以 OH 取代溴，并保留两个碳原子；水溶液条件较有利于这一取代分支，而非消去。
- Acid hydrolysis: Ethyl butyrate → Ethanol
水进攻与质子转移，使乙氧基片段以乙醇形式离去。另一部分重新形成羰基，生成丁酸。
参考文献
- Oxidation of alcoholsJim Clark · Chemguide · 2015
2026-09-08 核对。用于具体分子实例和一般反应范围；未提供制备操作规程或产率保证。
- Core practical 5: Investigate the oxidation of ethanolPearson Education Limited · Pearson qualifications
Distillation versus reflux in primary-alcohol oxidation; product tests and chromium waste controls.
- Pearson Edexcel International Advanced Level Chemistry Student Practical GuidePearson Education Limited · Pearson qualifications · 2018
Supports the practical distinctions between reflux, distillation, liquid-liquid separation, washing and drying in organic preparations.
- Reflux and distillation – practical videosRoyal Society of Chemistry · RSC Education
Explains the different purposes and apparatus arrangements for reflux and distillation, including organic preparation and work-up.
- Infrared spectroscopy: introductionRoyal Society of Chemistry · RSC Education
Molecular vibrations, functional-group absorptions and fingerprint comparison; no fabricated sample spectra.