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Chapter 16
Functional Group
Aldehydes
Carbonyl (-C=O)
Contains a polar bond
RCHO
Aliphatic chains
NOT as part of ...
Aliphatic rings or
Aromatic rings
Nomenclature
Aldehydes
IUPAC
Alkanal
Carbonyl C = #1
Common
Prefixaldehyde
ALDEHYDES & KETONES
Ketones
Carbonyl (-C=O)
Contains a polar bond
RCOR
Aliphatic chains
Aliphatic rings
NOT as part of Aromatic rings
Ketones
Alkanone
Carbonyl C = lowest # possible
Propanone = acetone
Alkyl alkyl ketone
Multi-functional Group Compounds
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
alkoxyAlkyl
alkylHalogen
haloIsomerism
Aldehydes
Constitutional
Skeletal
Ketones
Skeletal
Positional
Common & Naturally Occurring Aldehydes & Ketones
Aldehydes
Ketones
Formaldehyde
Acetone
Acetaldehyde
Odors/Flavors
Odors/Flavors
Cloves (2-heptanone)
Vanillin
Butter (butanedione)
Benzaldehyde
Fresh-mown hay (coumarin)
Cinnamaldehyde
Steroid Hormones
Testosterone
Progesterone
Cortisone
Physical Properties
Aldehydes
Ketones
Boiling Point
Alkanes<Aldehydes<Alcohols
Same as for Aldehydes
Bonding/polarity
Water Solubility
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Water can H-bond with aldehydes
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Mass relationship
Same as for Aldehydes
Acetone is infinitely soluble*
Odors
Low MW = unpleasant
High MW = fragrant
Preparation Reactions
Aldehydes
Oxidation
1˚ alcohol --> aldehyde
Pleasant
Perfumes & air fresheners
Ketones
2˚ alcohol --> ketone
Chemical Reactions - Oxidation
Aldehydes
Aldehyde --> Carboxylic acid
Ketones
Ketone --> NR
Chemical Reactions - Tollen’s Reagent
Aldehydes
RCHO + Ag+ -->RCOOH + Ag(s)
Ketones
RCOR + Ag+ --> NR
Chemical Reactions - Fehling’s or Benedict’s Reagent
Aldehydes
Ketones
RCHO + Cu2+ --> RCOOH + Cu2O
RCOR + Cu2+ --> NR
Diabetes test
Chemical Reactions – Reduction (Opposite of Oxidation)
Aldehydes
Ketones
RCHO --> 1˚ alcohol
RCOR --> 2˚ alcohol
Chemical Reactions - Reaction with Alcohol
Aldehydes
Ketones
RCHO + ROH --> Hemiacetal
RCOR + ROH --> Hemiacetal
(unstable, unless cyclic)
Hemiacetal + ROH --> Acetal
Hemiacetal + ROH --> Acetal
Hydrolysis of acetal produces the
aldehyde + 2 alcohol molecules
CH2(OCH3)2 --> HCHO + 2CH3OH
Hydrolysis of acetal produces the
ketone + 2 alcohol molecules
Phenol + Formaldehyde: Phenols and formaldehyde react via substitution reactions and
polymerize via dehydration reactions.
Plastics and adhesives (for plywood)
DMSO (dimethyl sulfoxide): sulfur analog of Acetone
Penetrates skin very quickly.
Anti-inflammatory rub
Reduces to dimethyl sulfide in the body.
Garlic-like odor
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
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