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Aldehydes - Coggle Diagram
Aldehydes
How to make Aldehydes?
- Oxidation of Primary Alcohols
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- Oxidation of Alkenes with hot, concentrated KMnO4 if the carbon is bonded to one H atom and one alkyl group
Reduction of Aldehydes
Requirements:
- Reducing agent is usually aqueous alkaline solution of sodium tetrahydridoborate (NaBH4) or lithium tetrahydridoaluminate (LiAlH4) in dry ether.
- If NaBH4 is used, aldehyde must be warmed with an aqueous alkaline solution of NaBH4.
- If LiAlH4 is to be used, make sure to add dissolved LiAlH4 in a dry ether like diethyl ether at room temperature.
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Oxidation
Aldehydes readily oxidize under mild conditions. Ketones + Excess Oxidising Agent --> Carboxylic Acids
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Fehling's Solution
Requirements and Observations:
- Ketone must be warmed with Fehling's Solution
- No color change, solution remains clear blue
Requirements and Observations:
- Aldehyde must be warmed with Fehling's Solution
- Color changes from clear blue to opaque red/orange
- Cu2+ ions reduced to Cu+ ions
Tollen's Reagant
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What is Tollen's Reagant?
- Aqueous solution of AgNO3 in excess ammonia solution.
Requirements and Observations:
- Aldehyde must be warmed with Tollen's Reagant
- Ag+ ions reduced to Ag atoms
- Mirror forms on inside of tube
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