Download L4 - Carboxylic Acids

Carboxylic
Acids
Carboxylic acids
and Their Salts
• Have hydroxyl
group bonded
to carbonyl
group.
• Tart tasting.
• Carboxylic
acids are weak
acids..
Naming Carboxylic Acids
Find the longest carbon chain that
contains the –COOH group.
Drop the –e from the end of the alkane
name and substitute –oic acid.
Number the longest chain. Carbon
number 1 is the carboxyl carbon.
Name and number other substituents.
Examples:
Aromatic acid names are derived from
the parent compound, benzoic acid.
Example:
1
Name the Following:
Physical Properties of Carboxylic Acids
1.
OH
OH
2.
:O:
3.
OH
4.
HO
The carboxylate group is very polar.
Hydrogen bonding between carboxylates
creates dimers (two identical molecules
bonded together).
:
5.
:Br:
HO
OH
:O:
:O:
Notice,
The boiling
points of
carboxylic
acids are
higher that
that of
alcohols
This gives carboxylic acids high boiling
points (greater than alcohols).
Physical Properties, cont.
Carboxylate groups can hydrogen bond
with water. If the hydrophobic –R group
is not too large, carboxylic acids are very
water soluble.
Long chained carboxylic acids were first
extracted from fats and are called “fatty
acids”
Insoluble carboxylic acids, or fats,
form a monomolecular layer when placed
in water due to the polar carboxyl group.
Acidity of Carboxylic
Acids
Carboxylic acids
behave as weak acids
(low dissociation),
forming carboxylate
ions in water.
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Examples:
Carboxylic Acid Reactions
Formation
Formation of a carboxylate
salt
(Ionization substitution) Carboxylic acids
react readily with strong bases (NaOH,
KOH) to form salts.
Acid
dissociation
results in the
formation of a
carboxylate ion
Examples:
Carboxylate Salts
• To name a carboxylic acid salt, name the
metal ion first and change the –ic ending of
the acid to –ate.
Example:
Useful Carboxylic Acid Salts
Na and K salts of long-chain acids are used
as soaps (sodium stearate).
Calcium and sodium
propanoate are used as
preservatives in bakery
products.
Sodium benzoate is a
food preservative used in
ketchup and soda pop.
Zinc 10-undecylenate is
used to treat athelete’s
foot.
overheads
Hey kids,
ask me
about
micelles and
how soaps
get us so
squeaky
clean!
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