Chemistry > Aldehydes and Ketones > 15.0 Oxidation of Aldehydes And Ketones
Aldehydes and Ketones
1.0 Introduction
2.0 Methods of Preparation
2.1 Aldehydes by Oxidation of 1° Alcohol
2.2 Ketones by Oxidation of 2° Alcohol
2.3 Aldehydes by Reduction of Acyl Chlorides, Esters and Nitriles
2.4 Aldehydes from Acyl Halides
2.5 Aldehydes from Esters and Nitriles
2.6 By heating calcium salt of fatty acids
2.7 Hydroboration of Alkynes
2.8 Hydration of Alkynes
2.9 Gattermann-Koch Reaction
2.10 Gattermann Reaction
2.11 Freidel Crafts Acylation
2.12 By Oxidation of Alkyl Benzenes
2.13 Etard’s Reaction
3.0 Physical Properties
4.0 Relative Reactivities of Carbonyl Compounds
4.1 Relative Reactivities towards Nucleophilic addition
4.2 Rate of Nucleophilic Substitution
4.3 Reactivitiy Considerations
5.0 Addition of Carbon Nucleophiles
6.0 Haloform Reactions
7.0 Aldol Condensations
8.0 Claisen Condensation
9.0 Intramolecular Claisen Condensation
9.1 Dieckmann Condensation
9.2 Perkin Reaction
9.3 Mechanism:
9.4 Knoevenagel Reaction
9.5 Mechanism
10.0 Cannizzaro Reaction
11.0 Reformatsky Reaction
12.0 Addition of Nitrogen Nucleophiles
12.1 Mechanism and pH dependence of Rate of Reaction of Imine (>C = N-) Formation
12.2 Addition of Secondary Amines: Formation of Enamine
12.3 Mechanism for Enamine Formation
12.4 Addition of Ammonia: Reductive Amination
13.0 Addition of Oxygen Nucleophile
13.1 Addition of Water
13.2 Mechanism
13.3 Mechanism for Acid-Catalysed Hydrate Formation
13.4 Addition of Alcohols
13.5 Mechanism for the Reaction
13.6 Acid-Catalyzed Hemiacetal Formation
13.7 Base-Catalyzed Hemiacetal Formation
13.8 Acid-Catalyzed Acetal Formation
13.9 Acetals are Protecting Groups
14.0 Addition of Sulphur Nucleophile
15.0 Oxidation of Aldehydes And Ketones
15.1 Tollen’s Reagent
15.2 Fehling Solution
15.3 Benedict’s Solution
15.4 Schiff’s Reagent
15.5 Baeyer-Villiger Oxidation
15.6 Oppenauer Oxidation
15.7 Oxidation of Aldehydes And Ketones With $S{O_2}$
16.0 Reduction of Aldehyde and Ketones
16.1 Addition of Hydride Ion
16.2 Meerwein-Ponndorf-Verley Reduction
16.3 The Wolf Kishner Reduction
16.4 Mechanism for Wolff-Kishner
16.5 Clemmensen Reduction
17.0 Other Reactions Of Aldehydes And Ketones
17.1 Wittig Reaction
17.2 Pinacol-Pinacolone Rearrangement
17.3 Benzoin Condensation
17.4 Schimdt Reaction
17.5 Benzilic acid Rearrangement
17.6 The Beckmann Rearrangement
17.7 Reaction of Formaldehyde with Ammonia
15.6 Oppenauer Oxidation
2.2 Ketones by Oxidation of 2° Alcohol
2.3 Aldehydes by Reduction of Acyl Chlorides, Esters and Nitriles
2.4 Aldehydes from Acyl Halides
2.5 Aldehydes from Esters and Nitriles
2.6 By heating calcium salt of fatty acids
2.7 Hydroboration of Alkynes
2.8 Hydration of Alkynes
2.9 Gattermann-Koch Reaction
2.10 Gattermann Reaction
2.11 Freidel Crafts Acylation
2.12 By Oxidation of Alkyl Benzenes
2.13 Etard’s Reaction
4.2 Rate of Nucleophilic Substitution
4.3 Reactivitiy Considerations
9.2 Perkin Reaction
9.3 Mechanism:
9.4 Knoevenagel Reaction
9.5 Mechanism
12.2 Addition of Secondary Amines: Formation of Enamine
12.3 Mechanism for Enamine Formation
12.4 Addition of Ammonia: Reductive Amination
13.2 Mechanism
13.3 Mechanism for Acid-Catalysed Hydrate Formation
13.4 Addition of Alcohols
13.5 Mechanism for the Reaction
13.6 Acid-Catalyzed Hemiacetal Formation
13.7 Base-Catalyzed Hemiacetal Formation
13.8 Acid-Catalyzed Acetal Formation
13.9 Acetals are Protecting Groups
15.2 Fehling Solution
15.3 Benedict’s Solution
15.4 Schiff’s Reagent
15.5 Baeyer-Villiger Oxidation
15.6 Oppenauer Oxidation
15.7 Oxidation of Aldehydes And Ketones With $S{O_2}$
16.2 Meerwein-Ponndorf-Verley Reduction
16.3 The Wolf Kishner Reduction
16.4 Mechanism for Wolff-Kishner
16.5 Clemmensen Reduction
17.2 Pinacol-Pinacolone Rearrangement
17.3 Benzoin Condensation
17.4 Schimdt Reaction
17.5 Benzilic acid Rearrangement
17.6 The Beckmann Rearrangement
17.7 Reaction of Formaldehyde with Ammonia
The reaction is the reverse of Meerwein-Ponndorf-Verley reduction. The reaction involves the oxidation of a secondary alcohol with a ketone and a base to the corresponding ketone of the alcohol.
Commonly used ketones are acetone, methyl ethyl ketone and cyclohexanone. Commonly used bases are aluminium ter-butoxide, aluminium isoporpoxide, potassium tri-tert-butoxide, etc.
Thus when a secondary alcohol in acetone or cyclohexanone is refluxed with aluminium tert-butoxide in benzene or toluene solution, the secondary alcohol is dehydrogenated to a ketone and the hydrogens are transferred to acetone or cyclohexanone converting them to alcohols.
Primary alcohols may also be oxidized to aldehydes if ketones is replaced by a better hydrogen acceptor, e.g., p-benzoquinone. The equilibrium can be controlled by the amount of acetone, an excess of which favours the oxidation of the alcohol.
Mechanism: The mechanism is the reverse of Meerwein-Ponndorf-Verley reaction. The alcohol and aluminium tri-tert-butoxide react to form aluminium derivative of the 2° alcohol. Metal alkoxides undergo rapid acid-base exchange with their corresponding alcohols].
The aluminium derivative then forms with acetone a cyclic transition state which undergoes internal hydride ion transfer, resulting in the oxidation of the alcohol to ketone.
Since the initial attack is on the alcoholic hydroxyl group, hindered alcoholic group react less readily. Thus, in cyclohexanols, the axial hydroxyl groups are attacked less readily.
