Download What are carboxylic acids?

What are carboxylic acids?
• Carboxylic acids are compounds which contain
a Carboxyl group.
• The -COOH group is attached either to a
hydrogen atom or to an alkyl group.
Carboxylic acids
Aliphatic
Monocarboxylic
Acid
Aromatic
Dicarboxylic
Acid
Polycarboxylic
Acid
Physical Properties
• Boiling point
The boiling points of carboxylic acids of similar
size are higher than alcohols.
The higher boiling points of the carboxylic
acids are still caused by hydrogen bonding.
In a pure carboxylic acid, hydrogen bonding
can occur between two molecules of acid
O H O
C R
R C
O H O
hydrogen bond between the fairly
positive hydrogen atom and a lone
pairon the fairly negative oxygen
atom.
There are 3 polar bonds: 1. C=O
2. C-O
3. O-H
They cause reactivity
high solubility in
aqueous media
• Carboxylic acid derivatives also contains a
carboxyl group, but now there is an
electronegative atom (oxygen, nitrogen, or a
halogen) attached to the carboxyl carbon. This
difference in structure leads to a major change
in reactivity.
Chemical Properties
1. Sodium Bicarbonate test (acidity test)
General test for carboxylic acids
O
RCOH + NaHCO3
O
RCO Na + H2O + CO2
bubbles
Evolution of a carbon dioxide gas is a positive
test for the presence of the carboxylic acid
2. Ferric Chloride test
O
RCOH + FeCl3
O
(RCO)3Fe + 3NH3
Ammonium chloride  Red Coloration
Oxalic acid + Ammonium Oxalate  Lime Green
Benzoic acid  Tan
3. Calcium Chloride test
Ammonium acetate  Clear
Di acid + Ammonium salts  White ppt