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Questions and Answers
What is the product of reducing an aldehyde with sodium borohydride (NaBH4)?
What is the product of reducing an aldehyde with sodium borohydride (NaBH4)?
What type of alcohol is produced when a ketone is reduced?
What type of alcohol is produced when a ketone is reduced?
In the Wolff–Kishner reduction, which compound is required for the reaction?
In the Wolff–Kishner reduction, which compound is required for the reaction?
Which of the following is a characteristic of catalytic hydrogenation of carbonyl compounds?
Which of the following is a characteristic of catalytic hydrogenation of carbonyl compounds?
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What reducing agent is commonly used to convert ketones into secondary alcohols?
What reducing agent is commonly used to convert ketones into secondary alcohols?
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What is the primary product of the Cannizzaro reaction when two molecules of an aldehyde are reacted?
What is the primary product of the Cannizzaro reaction when two molecules of an aldehyde are reacted?
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In the crossed Cannizzaro reaction, what happens to the formaldehyde when mixed with another aldehyde in the presence of conc. NaOH?
In the crossed Cannizzaro reaction, what happens to the formaldehyde when mixed with another aldehyde in the presence of conc. NaOH?
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During the hemiacetal to acetal conversion, what occurs after the protonation of the hemiacetal?
During the hemiacetal to acetal conversion, what occurs after the protonation of the hemiacetal?
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What is a characteristic of the aldol condensation reaction?
What is a characteristic of the aldol condensation reaction?
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What is produced when two aldehydes are reacted in a crossed aldol condensation where one aldehyde does not have any α-hydrogens?
What is produced when two aldehydes are reacted in a crossed aldol condensation where one aldehyde does not have any α-hydrogens?
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What role does the hydroxide base play in the Cannizzaro reaction?
What role does the hydroxide base play in the Cannizzaro reaction?
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In the reaction mechanism of hemiacetal to acetal, what type of catalyst is required?
In the reaction mechanism of hemiacetal to acetal, what type of catalyst is required?
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What is the result of deprotonation in the conversion of hemiacetals to acetals?
What is the result of deprotonation in the conversion of hemiacetals to acetals?
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What type of alcohol is produced from the reduction of ketones?
What type of alcohol is produced from the reduction of ketones?
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Which reagent is NOT commonly used for the reduction of aldehydes?
Which reagent is NOT commonly used for the reduction of aldehydes?
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What is the product formed when cyanide is added to an aldehyde?
What is the product formed when cyanide is added to an aldehyde?
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Which of the following describes the products formed from aldehydes reacting with alcohols?
Which of the following describes the products formed from aldehydes reacting with alcohols?
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What is the role of acid in the reaction between ketones and alcohols?
What is the role of acid in the reaction between ketones and alcohols?
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Which type of compound is formed when a carbonyl compound reacts with a derivative of ammonia?
Which type of compound is formed when a carbonyl compound reacts with a derivative of ammonia?
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What is the mechanism involved in the reaction of carbonyl compounds with nucleophiles?
What is the mechanism involved in the reaction of carbonyl compounds with nucleophiles?
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Which types of alcohols are produced from the reduction of aldehydes and ketones, respectively?
Which types of alcohols are produced from the reduction of aldehydes and ketones, respectively?
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What type of reaction occurs when a carbonyl compound reacts with alcohol in the presence of an acid?
What type of reaction occurs when a carbonyl compound reacts with alcohol in the presence of an acid?
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Study Notes
Preparation of Aldehydes and Ketones
- Alcohols can be oxidized to produce aldehydes and ketones.
- Primary alcohols are oxidized to aldehydes, which can then be further oxidized to carboxylic acids.
- Secondary alcohols are oxidized to ketones.
- Oxidizing agents include KMnO₄ or K₂Cr₂O₇.
Reactions of Aldehydes & Ketones
- Oxidation: Aldehydes are easily oxidized to carboxylic acids, while ketones are resistant to oxidation.
- Haloform: Reaction of methyl ketones and aldehydes with halogen in the presence of base forms haloform.
- Reduction: Carbonyl groups (C=O) in aldehydes and ketones can be converted to methylene groups (CH₂) through Clemmensen reduction (Zn/Hg/conc. HCl) or Wolff-Kishner reduction (heat with hydrazine and KOH in high-boiling alcohol).
- Nucleophilic Addition to Carbonyl: Addition of cyanide, derivatives of ammonia (e.g., cyanides, hydrazines, hydroxylamines, semicarbazides, and 2,4-dinitrophenylhydrazones), and alcohols to the carbonyl group.
- Cannizzaro Reaction: A redox reaction where two molecules of an aldehyde, without α-hydrogens, are reacted using a hydroxide base to produce an alcohol and a carboxylic acid.
- Aldol Condensation: Dimerization of aldehydes containing α-hydrogen atoms in alkaline media to form β-hydroxyaldehydes.
- Addition of Grignard Reagents: Grignard reagents (RMgX) react with aldehydes and ketones to form larger alcohols.
1- Oxidation
- Aldehydes easily oxidized to carboxylic acids.
- Ketones resistant to oxidation.
2- Haloform Reaction
- Reaction of methyl ketones and aldehydes with halogen in base to form haloform (after C-C cleavage).
- The aldehyde/ketone must have CH₃CO– group.
3- Reduction
- Conversion of carbonyl groups (C=O) to methylene groups (CH₂) using Clemmensen or Wolff-Kishner reduction.
- Zn/Hg/conc. HCl or NH₂NH₂, KOH used.
Reduction of Aldehydes and Ketones
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Aldehydes: Reduced to primary alcohols
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Ketones: Reduced to secondary alcohols
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Reducing agents: LiAlH₄, NaBH₄, catalytic hydrogenation (Pd/H₂)
Nucleophilic Addition to Carbonyl
- Addition reactions to the carbonyl carbon of aldehydes and ketones, involving nucleophiles.
- Mechanism often involves protonation, nucleophilic attack, and deprotonation.
4i) Addition of Cyanide
- Reaction of aldehydes/ketones with cyanide (NaCN) followed by acid hydrolysis to yield cyanohydrins.
4ii) Addition of Derivatives of Ammonia
- Addition of hydrazine, hydroxylamine, semicarbazide, and 2,4-dinitrophenylhydrazine to carbonyls
4iii) Addition of Alcohols
- Reaction with alcohols in presence of acid to form hemiacetals and acetals.
- Reaction with alcohols in presence of base to form hemiacetals and ketals.
5- Cannizzaro Reaction
- A redox reaction of aldehydes without α-hydrogens in presence of base to yield alcohol and carboxylic acid.
6- Aldol Condensation
- Dimerization reaction of aldehydes containing α-hydrogens in alkaline conditions to produce β-hydroxyaldehydes.
7) Addition of Grignard reagents
- Grignard reagents (RMgX) react with aldehydes and ketones producing larger alcohols.
Amines
- An amine with one carbon attached to nitrogen is a primary amine.
- Two carbons attached to nitrogen is a secondary amine.
- Three carbons attached to nitrogen is a tertiary amine.
- Amines are more polar than alkanes but less polar than alcohols.
Preparation of Amines (by Alkylation of Ammonia and Reduction)
- Alkylation of ammonia with alkyl halides forms amines.
- Acid amides can be reduced to amines.
Inductive Effects and Basicity
- Electron-donating groups increase basicity of amines.
- Electron-withdrawing groups decrease basicity.
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Description
This quiz covers the preparation methods and chemical reactions of aldehydes and ketones. It includes oxidation processes, nucleophilic additions, and specific reagents used in these reactions. Test your understanding of these important organic compounds and their transformations.
