1. Name as Substituent
On a molecule with a higher priority functional group, C=O is oxo- and -CHO is formyl.
Aldehyde priority is higher than ketone.
3-methyl-4-oxopentanal
3-formylbenzoic acid
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2. 4.5 Isomerism in aldehydes and ketones
Aldehydes and ketones are constitutional isomers
Aldehydes and ketones can have skeletal and positional isomers if there are enough carbons.
Stereoisomers are also possible if there is a ring or C=C in the molecule

3. 4.6 Selected Common aldehydes and ketones
Formaldehyde
Acetone
Vanillin
Benzaldehyde
Cinnamaldehyde
Butanedione

4. Formaldehyde Gas at room temperature.
Formalin is a 40% aqueous solution.
trioxane, m.p. 62C
formaldehyde,
b.p. -21C
formalin
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5. Industrial Importance
Acetone and methyl ethyl ketone are important solvents.
Formaldehyde used in polymers like Bakelite.
Flavorings and additives like vanilla, cinnamon, artificial butter =>

6. Formaldehyde -formalin
Acetone – solvent and metabolic product
Vanillin - vanilla flavoring
Benzaldehyde - almond flavor
Cinnamaldehyde - cinnamon
Butanedione - butter

7. 4.7 Physical properties Boiling points – page 121
Solubility – water solubility page 123

8. Boiling Points
More polar, so higher boiling point than comparable alkane or ether.
Cannot H-bond to each other, so lower boiling point than comparable alcohol.
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9. Solubility Good solvent for alcohols.
Lone pair of electrons on oxygen of carbonyl can accept a hydrogen bond from O-H or N-H.
Acetone and acetaldehyde are miscible in water =>

10. 4.8 Preparation of Aldehydes and Ketones
Oxidation
2 alcohol + Na2Cr2O7  ketone
1 alcohol  aldehyde