Download Aldehydes, Ketones and Carboxylic Acids

Aldehydes and Ketones
AH Chemistry
Unit 3(b)
Functional Group
• What is the functional group of the
aldehydes and ketones?
• What type of bonds link the C and O
atoms?
Physical Properties
• How do the boiling points compare to
alkanes?
– Why?
• How do the boiling points compare to
alcohols?
– Why?
• Can aldehydes and ketones set up
hydrogen bonds with each other?
• Can they set them up with water?
Chemical reactions
• What are the characteristic reactions of
aledehydes and ketones?
– Reduction
– Nucleophilic addition
– Nucleophilic addition-elimination
• Which is more susceptible to nucleophilic
attack, aldehyde or ketone?
– Why?
Oxidation
• What reagents can be used to oxidise
aldehydes?
Reduction
• Aldehydes and ketones can be reduced to
produce alcohols.
• The reducing agent of choice is LiAlH4
- lithium aluminium hydride
• Able to transfer a hydride ion to the partially
positive carbon atom of the carbonyl group
• Musty be carried out in anhydrous conditions (in
ether)
Nucleophilic addition
• With HCN, producing cyanohydrins....
• The cyanohydrins can be hydrolysed to
produce hydroxy carboxylic acids
Nucleophilic addition-elimination
- With hydrazine, H2N-NH2
- Produces hydrozones
Nucleophilic addition
Elimination
CONDENSATION
- With 2,4-dinitrophenylhydrazine
- Produces 2,4-dinitrophenylhydrozones
These products are “derivatives”.
They are crystalline solids with characteristic melting points.
The melting point of the derivative can be used to identify the orignial
carbonyl compound.