Questions in this category deal with the carbonyl family: aldehydes, ketones and carboxylic acids. Expect items on structure and naming, methods of preparation, characteristic reactions and the tests used to tell these compounds apart. A useful set for revising this part of organic chemistry.
Propanal (CH₃CH₂CHO) reacts with CH₃CH₂MgBr, adding an ethyl group to the carbonyl carbon, forming pentan-3-ol (CH₃CH₂CH(OH)CH₂CH₃) after hydrolysis.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
Heating calcium propanoate ((CH₃CH₂COO)₂Ca) forms pentan-3-one (CH₃CH₂COCH₂CH₃) and releases CO₂ as a byproduct.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
Butanal (CH₃CH₂CH₂CHO) reacts with NH₂OH to form an oxime (CH₃CH₂CH₂CH\=NOH), but the carbonyl carbon becomes chiral in the intermediate, yielding a racemic mixture.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
Reactivity decreases with steric hindrance and conjugation: CH₃COCH₂CH₃ (ketone) < C₆H₅CHO (aromatic aldehyde) < CH₃CH₂CHO (aliphatic aldehyde).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
LiAlH₄ reduces carboxylic acids to primary alcohols. Propanoic acid (CH₃CH₂COOH) yields propan-1-ol (CH₃CH₂CH₂OH).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
Neutral KMnO₄ oxidation of terminal alkynes like 1-pentyne (CH≡CCH₂CH₂CH₃) forms carboxylic acids, but the PDF notes preparation of aldehydes via specific oxidations; corrected to butanoic acid contextually, though pentanal (CH₃CH₂CH₂CH₂CHO) fits preparation scope.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
The compound has a 5-carbon chain with a ketone on C-2, a double bond between C-3 and C-4, and a methyl group on C-4: CH₃COCH\=C(CH₃)CH₃.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
Heating calcium acetate ((CH₃COO)₂Ca) decarboxylates it to acetone (CH₃COCH₃), so acetone remains unchanged in this context, but the reaction confirms its formation.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
2,3-Dimethylbut-2-ene ((CH₃)₂C\=C(CH₃)₂) cleaves symmetrically to form two molecules of acetone (CH₃COCH₃), a ketone.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
Ozonolysis of propene (CH₃CH\=CH₂) cleaves the double bond, forming ethanal (CH₃CHO) and methanal (HCHO) after hydrolysis.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
4-Methylpent-1-ene (CH₂\=CHCH₂CH(CH₃)₂) cleaves at the double bond, forming methanal (HCHO) and 3-methylbutanal ((CH₃)₂CHCH₂CHO).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
Ozonolysis of 3-methyl-1-butene (CH₂\=CHCH(CH₃)₂) cleaves the double bond, forming methanal (HCHO) and 2-methylpropanal ((CH₃)₂CHCHO).
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids
