1. ALDEHYDES & KETONES
Melanin - a polymeric substance involving many interconnected cyclic ketone units that colors human hair & skin

2. Functional Group Ketones Aldehydes RCOR RCHO
Carbonyl (-C=O) in middle of chain
Contains a polar bond
RCOR
Aliphatic chains
Aliphatic rings
NOT as part of Aromatic rings
Aldehydes
Carbonyl (-C=O) at end of chain
Contains a polar bond
RCHO
Aliphatic chains
NOT as part of ...
Aliphatic rings or
Aromatic rings

3. Aldehydes and ketones are related to alcohols in a similar manner as alkenes are related to alkanes.

4. Nomenclature Aldehydes IUPAC Common Ketones IUPAC Common Alkanal
Carbonyl C = #1
Common
Prefixaldehyde
Ketones
IUPAC
Alkanone
Propanone = acetone
Carbonyl C = lowest # possible
Common
Alkyl alkyl ketone

5. Multi-functional Group Compounds
What name do you use when there is more than one functional group?
To determine which suffix to use, follow this priority list (high to low):
Substituent name
Aldehyde
Ketone oxo-
Alcohol hydroxy-
Alkene en- (before suffix)
Alkyne yn- (before suffix)
Alkoxy (ether) alkoxy-
Alkyl alkyl-
Halogen halo-

6. Isomerism Aldehydes Constitutional
Skeletal
Functional group (this is the second time we encounter this type of isomerism)
Ketones
Constitutional
Skeletal
Positional
Functional group

7. Common & Naturally Occurring Aldehydes & Ketones
Formaldehyde
methanal
Acetaldehyde
ethanal
Odors/Flavors
Vanillin
Benzaldehyde -->
Cinnamaldehyde
Lots of nuts & spices
Ketones
Acetone
propanone
Odors/Flavors
Cloves (2-heptanone)
Lots of nuts & spices
Butter (butanedione)
Fresh-mown hay (coumarin)
Steroid Hormones
Testosterone
Progesterone
Cortisone

9. Physical Properties Ketones Aldehydes Boiling Point Boiling Point
Same as for Aldehydes
Water Solubility
Acetone is infinitely soluble*
Odors
Pleasant
Perfumes & air fresheners
Aldehydes
Boiling Point
Alkanes<Aldehydes<Alcohols
Bonding/polarity
Water Solubility
Water can H-bond with aldehydes
Mass relationship
Odors
Low MW = unpleasant
High MW = fragrant

11. Preparation Reactions
Aldehydes
Oxidation
1˚ alcohol --> aldehyde
Ketones
Oxidation
2˚ alcohol --> ketone

12. Chemical Reactions - Oxidation
Aldehydes
Aldehyde --> Carboxylic acid
Ketones
Ketone --> NR

13. Chemical Reactions - Tollen’s Reagent
Aldehydes
RCHO + Ag+ -->RCOOH + Ag(s)
Ketones
RCOR + Ag+ --> NR
(a) An aqueous solution of ethanal is added to a solution of silver nitrate.
(b) The solution darkens as ethanal is oxidized to ethanoic acid.
(c) The inside of the beaker becomes coated with metallic silver.

14. Chemical Reactions - Fehling’s or Benedict’s Reagent
Aldehydes
RCHO + Cu2+ --> RCOOH + Cu2O
Diabetes test
Ketones
RCOR + Cu2+ --> NR

15. Chemical Reactions - Reduction (Opposite of Oxidation)
Aldehydes
RCHO --> 1˚ alcohol
Ketones
RCOR --> 2˚ alcohol

16. Chemical Reactions - Reaction with Alcohol
Aldehydes
RCHO + ROH --> Hemiacetal (unstable, unless cyclic)
Hemiacetal + ROH --> Acetal
Hydrolysis of acetal produces the aldehyde + 2 alcohol molecules
CH2(OCH3)2 + H2O --> HCHO + 2CH3OH
Ketones
RCOR + ROH --> Hemiacetal
Hemiacetal + ROH --> Acetal
Hydrolysis of acetal produces the ketone + 2 alcohol molecules

17. Phenol + Formaldehyde
Phenols and formaldehyde react via substitution reactions and polymerize via dehydration reactions.
Plastics and adhesives (for plywood)

18. DMSO (dimethyl sulfoxide)
Sulfur analog of Acetone
Penetrates skin very quickly.
Anti-inflammatory rub
Reduces to dimethyl sulfide in the body.
Garlic-like odor

19. What do you need to know?
Structural characteristics (know the functional group)
Aldehydes
Ketones
Acetals
Isomers
Nomenclature (the rules for naming the molecules)
Common & IUPAC
Physical properties (basic/simple)
BP; Solubility; Flammability
Occurrence and uses (common)
Natural (ex.: nuts & spices,melted butter odor, melanin )
Synthetic (ex.: formalin, Bakelite)
Preparation (what basic reactions produce the molecules)
Aldehydes - oxidation of 1˚ alcohols
Ketones - oxidation of 2˚ alcohols
Characteristic reactions of the molecules
Oxidation-reduction
Fehling’s & Tollens’ reactions
rxn w/ alcohols