Transcript 26-2: Aldehydes and Ketones

26-2: Aldehydes
and Ketones
Same functional group for both…
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The carbonyl (C=O)
Aldehydes
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Carbonyl is at the end of a hydrocarbon
chain; is also bonded to a hydrogen
General formula: R-CH=O (or R-CHO)
Naming:
1.
2.
Add –al to root name of the longest
hydrocarbon chain.
Name branch, giving address.
Ketones
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Carbonyl is in the middle of a hydrocarbon
chain
General formula: _____ (or R-CORl)
Naming:
1.
2.
3.
Add –one to root word of the longest
hydrocarbon chain.
Give address of carbonyl carbon.
Name branch, giving address.
Properties of Aldehydes and Ketones
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Carbonyl causes increased polarity,
causing stronger intermolecular forces with
higher boiling and melting points.
No hydrogen bonding occurs, so they have
lower boiling points than alcohols.
Uses of Aldehydes and Ketones
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Methanal (formaldehyde) is used in
polymer making; once used to preserve
specimens – is a known carcinogen.
Propanone (acetone) is a common solvent.
It is in used fingernail polish remover.
Many are used as flavorings in food and
candy, due to tastes and fragrances (vanilla
and cinnamon).