ALDEHYDES &
KETONES
CHAPTER 9
THE CARBONYL GROUP
 • The carbonyl group (C=O) is found in aldehydes,
ketones, and many other organic functional groups.
 • The carbon and oxygen in the carbonyl group are sp
hybridized, with bond angles of 120°.
2
–
FUNCTIONAL GROUPS CONTAINING
CARBONYL GROUPS
ALDEHYDE NOMENCLATURE
 IUPAC:
ALDEHYDE NOMENCLATURE
 COMMON METHOD: the name is created as a derivative
of the parent name followed by aldehyde and using the
greek alphabet as locators.
Common Name
 Name the following structures using the IUPAC mathod.
1.
2.
O
4.
5
6
3
4
Hexanal
O
5.
1
2
3.
H
3
4
2
1
H
3-Methylbutan al
6.
O
3
2
1
H
2-Prop enal
(Acrolein)
 Name the following structures using the IUPAC mathod.
1.
2.
butanal
2-ethylbutanal
O
4.
5
6
3
4
3.
5.
1
2
Hexanal
hexanal
O
H
3
1
benzaldehyde
6.
O
3
2
1
H
H
2-Prop enal
3-Methylbutan al
3-methylbutanal 2-propenal
(Acrolein)
4
2
KETONE NOMENCLATURE
IUPAC METHOD:
KETONE NOMENCLATURE
COMMON METHOD: Name alkyl groups that are attached to
each side of the carbonyl group in alphabetical order.
Butyl propyl ketone
 Name the following compounds in both the IUPAC and common methods.
 1.

2.
4.
3.
5.

common name

not required
 Name the following compounds in both the IUPAC and common methods.
 1.
2.
3.

propanone
2-butanone
3,4-dimethyl-2-pentanone

dimethyl ketone
ethyl methyl ketone methyl (1,2-dimethyl propyl)
ketone


4.

3-ethyl-2-pentanone

methyl (1-ethyl propyl) ketone
5.
cyclohexanone
--not required
 ADDITIONAL NOMENCLATURE RULES:
PHYSICAL PROPERTIES OF CARBONYLS
1. Carbonyls are slightly polar.
PHYSICAL PROPERTIES OF ALDEHYDES AND
KETONES
1. Carbonyls are slightly polar, however, since there
is no hydrogen on the carbonyl oxygen aldehydes
and ketones do not form hydrogen bonds with
themselves. They can hydrogen bond with water.
PHYSICAL PROPERTIES OF ALDEHYDES AND
KETONES
2. Carbonyls cause aldehydes and ketones to have
higher boiling points than comparable
hydrocarbons but lower than comparable alcohols.
PHYSICAL PROPERTIES OF ALDEHYDES AND
KETONES
3. Low molecular weight aldehydes and ketones are
water soluble; water solubility decreases as
molecular weight increases.
PHYSICAL PROPERTIES OF ALDEHYDES AND
KETONES
4. Aldehydes and ketones have distinct odors.
 Aldehydes are said to have sharp and irritating odors,
although as the molecular weight increases the odor
improves and becomes pleasant. Large molecular weight
aldehydes are often found in perfumes.
Ketones have sweet and pleasant odors. Fingernail
polish remover, acetone, is a very common household
ketone.
REACTIONS OF ALDEHYDES AND KETONES
Aldehydes and ketones can be produced by the
oxidation of alcohols.
REACTIONS OF ALDEHYDES AND KETONES
Aldehydes are easily oxidized, however, ketones do not
generally oxidize. This makes oxidation reactions an
easy way to distinguish between the two types of
compounds. When aldehydes are oxidized they form
carboxylate salts.
Common oxidizing agents are:
KMnO4 /Chromic Acid and K2Cr2O7 /H2SO4
REACTIONS OF ALDEHYDES AND KETONES
Oxidation of aldehydes:
Tollen’s reagent is a mild oxidizing agent composed of
silver ions in an aqueous basic solution of ammonia. When
the aldehyde is oxidized to carboxylate salt and the silver
ions are reduced to solid silver, which coats the bottom of
the tube with a “silver mirror”.
REACTIONS OF ALDEHYDES AND KETONES
Oxidation of aldehydes:
Benedict’s reagent is a mild oxidizing agent composed of
cuprous hydroxide in sodium citrate. When the aldehyde
is oxidized to carboxylate salt and the copper ions are
reduced to solid copper (I), which precipitates out as a red
solid.
REACTIONS OF ALDEHYDES AND KETONES
Reduction of aldehydes and ketones:
Aldehydes and ketones are reduced to form alcohols when
they react with hydrogen gas in the presence of a catalyst.
Common reducing catalysts are nickel, platinum, or
palladium. Aldehydes will return to primary alcohols and
ketones will return to secondary alcohols.
REACTIONS OF ALDEHYDES AND KETONES
Reduction of aldehydes and ketones:
The most common laboratory reagent for the reduction of an
aldehyde or ketone is sodium borohydride, NaBH4.
This reagent contains hydrogen in the form of hydride ion, H:-.
In a hydride ion, hydrogen has two valence electrons and
bears a negative charge.
In a reduction by sodium borohydride, hydride ion adds to the
partially positive carbonyl carbon which leaves a negative
charge on the carbonyl oxygen.
Reaction of this intermediate with aqueous acid gives the
alcohol.
REACTIONS SUMMARY
or carboxylate
salt