This category covers the basics of aldehydes and ketones: how they are named under common and IUPAC systems, the structure and bonding of the carbonyl group, and the routes used to prepare them in the laboratory. Good practice before moving on to their reactions.
Hexan-3-one (CH₃CH₂COCH₂CH₂CH₃) undergoes self-aldol condensation to form 4-hydroxy-3-propylheptan-5-one (CH₃CH₂C(OH)(CH(CH₂CH₃)COCH₂CH₃)CH₂CH₃), a nine-carbon β-hydroxy ketone.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Butanal (CH₃CH₂CH₂CHO) undergoes self-aldol condensation to form 2-ethyl-3-hydroxyhexanal (CH₃CH₂CH₂CH(OH)CH(CH₂CH₃)CHO), a six-carbon β-hydroxy aldehyde.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Propanal (CH₃CH₂CHO) undergoes aldol condensation with itself, forming an aldol product that dehydrates to but-2-enal (CH₃CH\=CHCHO).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Acetone (CH₃COCH₃) undergoes self-aldol condensation, forming 4-methylpent-3-en-2-one (CH₃COCH\=C(CH₃)₂) after dehydration.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Oxidation of ethanal (CH₃CHO) with a strong oxidizing agent like K₂Cr₂O₇/H₂SO₄ yields ethanoic acid (CH₃COOH).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Tollens' test oxidizes aldehydes like ethanal (CH₃CHO) to carboxylic acids, forming a silver mirror, but does not react with ketones like acetone.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Propanal (CH₃CH₂CHO) is an aldehyde (positive Tollens' test) but lacks a CH₃C\=O group (negative iodoform test).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Tollens' test is specific to aldehydes. Cyclohexanone (C₆H₁₀O), a ketone, does not reduce Tollens' reagent.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Fehling’s solution oxidizes aliphatic aldehydes like ethanal (CH₃CHO) to form a red precipitate, but does not react with aromatic aldehydes like benzaldehyde (C₆H₅CHO).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Propanal (CH₃CH₂CHO) is an aliphatic aldehyde (positive Fehling’s test) with α-hydrogens (undergoes aldol condensation).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Hexanal (CH₃CH₂CH₂CH₂CH₂CHO), a six-carbon aliphatic aldehyde, reduces Fehling’s solution to form a red Cu₂O precipitate.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
Reactivity decreases with steric hindrance. Di-tert-butyl ketone (bulky) < Acetone (less hindered) < Acetaldehyde (least hindered, aldehyde more reactive).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Nomenclature, Structure and Preparation of Aldehydes and Ketones
