醛
醛与氰根发生亲核加成，生成羟基腈，将有机路径从卤代烷扩展至羰基化学。
- 官能团
- CHO
- Also known as
- alkanals, aldehyde, carbonyl compounds
概览
Carbonyl compounds with a terminal C=O group.
An aldehyde has a carbonyl carbon bonded to at least one hydrogen. It can be reduced to a primary alcohol or oxidised to a carboxylic acid. Nucleophilic addition changes the planar carbonyl centre into a tetrahedral centre; a new stereocentre may give a racemic product when neither reagents nor surroundings are chiral.
Identifiers
- 官能团
- CHO
- Also known as
- alkanals, aldehyde, carbonyl compounds
化学标识符
- SMILES
- CC=O
性质
- 反应选择
- 还原不改变碳原子数；氰根加成使碳链增加一个碳原子。
- 试验结果解读
- 2,4-DNPH 试验可提示存在醛或酮；需另做氧化试验来区分两者。
Diagnostic tests
2,4-二硝基苯肼羰基试验
- 试剂
- 2,4-二硝基苯肼
- 条件
- 室温
- Positive observation
- 橙色沉淀
- Negative observation
- 无橙色沉淀
- Interpretation
- 醛或酮与此试剂形成沉淀；酯、羧酸及酰胺的羰基反应性另行区分。
- 适用范围
- 醛和酮可形成 2,4-二硝基苯腙。
- 来源说明
- 醛与酮均可呈阳性，结合衍生物熔点或光谱比较。
- 证据
- 教材核心内容
托伦试剂醛类试验
- 试剂
- 托伦试剂
- 条件
- 温和加热
- Positive observation
- 银镜
- Negative observation
- 酮在这些条件下通常不产生银镜
- Interpretation
- 醛还原托伦试剂，自身被氧化为羧酸盐。
- 适用范围
- 用于区分脂肪族羰基化合物中的醛和酮。
- 来源说明
- 还原糖与其他还原性物质也可能呈阳性，结合羰基与结构信息分析。
- 证据
- 教材核心内容
斐林试剂醛类试验
- 试剂
- 斐林试剂
- 条件
- 温热
- Positive observation
- 砖红色沉淀
- Negative observation
- 酮在这些条件下通常不产生砖红色沉淀
- Interpretation
- 脂肪醛还原斐林试剂，自身被氧化为羧酸盐。
- 适用范围
- 脂肪醛的常用定性试验。
- 来源说明
- 芳香醛通常呈阴性，还原糖可能呈阳性；与托伦试验及光谱比较。
- 证据
- 教材核心内容
Related compounds
- 甲醛
Methanal is the simplest molecule-level member of the aldehyde family.
- 乙醛
Ethanal is a two-carbon molecule-level member of the aldehyde family.
- 丙醛
一种三碳醛，可联系氧化与羰基加成反应。
- 丁醛
含四个碳原子的醛，末端羰基具有亲电性。
- 戊醛
戊醛是一种有机化合物，分子式为 C5H10O。
- 己醛
一种无支链的六碳醛，末端含一个羰基。
- 苯甲醛
一种芳香醛，可氧化为苯甲酸。
- 香兰素
香兰素是一种有机化合物，分子式为 C8H8O3。
- 肉桂醛
肉桂醛是一种有机化合物，分子式为 C9H8O。
- 乙二醛
乙二醛是一种有机化合物，分子式为 C2H2O2。
- 2-甲基丙醛
含四个碳原子的支链醛，是丁醛的构造异构体。
Connected reactions
- Cyanohydrin formation: Aldehydes → Hydroxynitriles
氰根与醛加成生成羟基腈，构成从羰基化合物出发、增加一个碳原子的路线。
- Oxidation: Alcohols → Aldehydes
伯醇经受控氧化可生成醛。
- Controlled oxidation: Primary alcohols → Aldehydes
伯醇经受控氧化可生成醛。
- Reduction: Aldehydes → Primary alcohols
醛还原生成伯醇。
- Oxidation: Aldehydes → Carboxylic acids
醛氧化生成羧酸。
- Grignard addition co reactant: Aldehydes → Secondary alcohols
醛与格氏试剂反应，经酸性后处理得到仲醇。
参考文献
- Organic Chemistry: Nucleophilic Addition Reactions of Aldehydes and KetonesJohn McMurry · OpenStax Organic Chemistry · 2023
Supports functional-group chemistry used to curate the linked examples. Checked 2026-09-16; named examples are applications of textbook scope, without claimed experimental yields.
- Pearson Edexcel International Advanced Level Chemistry Practical GuidePearson Education Limited · Pearson qualifications · 2018
Official Pearson practical guidance for organic qualitative tests, including bromine water, acidified dichromate, silver nitrate, carbonyl reagents and the iodoform reaction.
- Pearson Edexcel Level 3 Advanced GCE in Chemistry specificationPearson Education Limited · Pearson qualifications · 2024
Supports the textbook-core organic reaction routes used for displayed route and mechanism content.
- PubChem Compound Summary for FormaldehydeNational Center for Biotechnology Information · PubChem · 2026
Used for stable identifiers and basic compound metadata.
- PubChem Compound Summary for AcetaldehydeNational Center for Biotechnology Information · PubChem · 2026
Used for stable identifiers and basic compound metadata.
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- PubChem Compound Summary: 2-Methylpropanal (CID 6561)National Center for Biotechnology Information · PubChem
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