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Spencer L
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Slabaugh

www
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com/chemistry/seager

Chapter 14
Aldehydes and Ketones

Jennifer P
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• Ketones have two carbons attached to the carbonyl group
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• Change ending of the root hydrocarbon name by dropping –e
and adding –al
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• Examples:

3-bromobutanal

2-ethylbutanal

COMMON ALDEHYDES

NAMING KETONES
• Find the longest chain that contains C=O
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• Number the longest carbon chain so the C=O group has the
lowest number
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• Examples:

3-methyl-2-pentanone

2-methylcyclohexanone

COMMON KETONES

Chemistry Around Us
• DHA (dihydroxyacetone)
• The active ingredient in tanning lotions and creams that
chemically darken the skin

PHYSICAL PROPERTIES
• Because of the polarity of the C=O group, these groups can
interact, but the attraction is not as strong as hydrogen
bonding
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PHYSICAL PROPERTIES (continued)

PHYSICAL PROPERTIES (continued)
• The C=O group can hydrogen bond with water molecules
because the oxygen atom in the carbonyl group has a partial
negative charge that attracts the partial positive charge of a
hydrogen atom in the water molecule
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PHYSICAL PROPERTIES (continued)

ALDEHYDE AND KETONE REACTIONS
• Recall the oxidation of alcohols to produce aldehydes and
ketones:

• The difference in reactivity toward oxidation is the chief
reason why aldehydes and ketones are classified in
separated families
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• In general, ketones fail to react with these reagents
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After the addition of equal amounts
of K2Cr2O7, the acetone remains
unreacted, whereas the
benzaldehyde is oxidized
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ALDEHYDE AND KETONE REACTIONS
(continued)
• In the presence of aldehydes, Benedict’s reagent produces
a red precipitate
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5% glucose solution,
and 2
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The addition of Benedict’s
reagent from the first tube
produces colors (due to the
red Cu2O) that indicate the
amount of glucose present
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ALDEHYDE AND KETONE REACTIONS
(continued)
• The addition of alcohols to aldehydes produces an unstable
hemiacetal intermediate
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ALDEHYDE AND KETONE REACTIONS
(continued)
• Hemiketal general formula:

• Ketal general formula:

ALDEHYDE AND KETONE REACTIONS
(continued)
• Cyclic hemiacetals and hemiketals are more stable than
open-chains and are important in carbohydrate chemistry
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Hydrolysis is the cleavage of a bond by reaction with water

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