Transcript Aldehydes and Ketones

Aldehydes and Ketones
The Carbonyl Group
Definitions
Aldehyde is a functional group in which at
least one H is bonded to a carbonyl. R-C-H
||
O
Ketone is a functional group in which two
organic substiuents are bonded to a carbonyl.
R-C-R
||
O
Carbonyl is the carbon-oxygen double bond,
C=O
Nomenclature
Names are based on the longest continuous
chain of carbon atoms.
To name aldehydes, the –e of the parent
hydrocarbon is replaced with the aldehyde
suffix –al.
The aldehyde function is at the end of the
chain and numbering starts there.
To name the ketones, replace the –e with the
ketone suffix –one.
The chain is numbered so as to give the
ketone group the lowest possible. The
position of the ketone function is usually
indicated in the name.
Compounds with two aldehydes or ketones
are named dials and diones.
The use of common names for aldehydes is
prevalent. They are related to those of
carboxylic acids.
Common names for ketones are derived by
naming the alkyl groups attached to the
carbonyl carbon.
Properties
Carbonyl group of aldehydes and ketones
causes the molecules to be polar.
Higher boiling points than corresponding
hydrocarbons.
Simplest aldehyde is formaldehyde. Aromatic
aldehyde is benzaldehyde.
Simplest ketone is acetone.
They are used in natural fragrances and
flavorings dyes, vitamins, and hormones.
Carboxylic Acids
Carboxylic cid has a functional group in
which OH is attached to carbon-oxygen
double bond.
O
||
R-C-OH -CO2H
-COOH
Because of the structural features, the
carboxylic acid group is very reactive.
Properties
Carboxylic acids often have an unpleasant,
acrid odor and sour taste.
Carboxylic acids have the ability to form a
hydrogen bond.
Carboxylic acid has a significantly higher
boiling point than the alcohol. This is due to
the greater polarity of the O-H bond in the
carboxylic acids (C=O).
Lower molecular weight acids are water
soluble. The solubility decreases with
molecular weight.
Boiling points increase with molecular weight.
Nomenclature of Carboxylic
Acids
Name the longest chain of carbon atoms that
includes the acid group and replace the final
–e with the suffix –oic and the word acid.
If the acid group is directly attached to a ring,
the suffix carboxylic acid is used in naming.
An aromatic acid in which the acid group is
attached to a benzene ring is called benzoic
acid.
In numbering substituted carboxylic acids,
start with the carboxyl carbon.
Polyfunctional Carboxylic acids
For carbon-carbon double bonds, use the
suffix-en and for carbon-carbon triple bonds,yn.
The acid group is almost always named with
a suffix.
Other functional groups present are named
with prefixes
Name all other groups with prefixes and
number them.
Acid
-COOH
oic acid
Carboxy
Aldehyde
-CO
al
oxo
Ketone
-C-
one
oxo
Alcohol
-OH
ol
hydroxy
Amine
-NH2
amine
amino