Notes on Carboxylic Acids and Derivatives
Carboxylic acids are organic acids. Although not as strong as inorganic acids like hydrochloric acid (HCl),
they still can turn blue litmus paper to red. The carboxylic acids provide the sour taste associated with
foods.
RCOOH + H2O RCOO- + H3O+
The -COOH can be attached to either an alkyl group (RCOOH) or an aryl group (ArCOOH). Whether the
group is aliphatic or aromatic, saturated or unsaturated, substituted or unsubstituted, the properties of
the carboxyl group (-COOH) are essentially the same.
The -OH in carboxylic acids can be replaced by a number pf groups: -Cl, -OCOR (RCOO -), -OR, -NH2 to
yield compounds known as acid chlorides, acid anhydrides, esters, and amides. These compounds are
called functional derivatives of acids, they all contain the acyl group:
An aromatic ring bearing a carboxyl group undergoes electrophilic aromatic substitution characteristic of
a deactivating group
Carboxylic acids are much stronger acids than water. Aqueous hydroxides therefore can convert
carboxylic acids into salts; aqueous mineral acids can readily convert back the salts to carboxylic acids.
Carboxylic acids have high boiling points because of hydrogen bonding just like in alcohols. The extra O
(oxygen) makes the boiling points much higher than in alcohols of comparable molecular weights.
Dicarboxylic Acids
, Acid Chlorides, Acid Anhydrides, Esters and Amides
Acid chlorides are among the most reactive of carboxylic acid derivatives, and can be converted into
other types of compounds by nucleophilic acyl substitution.
Acid anhydrides are typically prepared from acid chlorides by nucleophilic acyl substitution with a
carboxylate ion (RCOO-). The chemistry of the acid anhydrides are the same as the acid chlorides,
although they react more slowly.
Esters are among the most widespread of all naturally occurring compounds. Most simple esters are
pleasant-smelling liquids that are responsible for the fragrant odors of fruits and flowers. Methyl
butanoate is a constituent of pineapple oil while isopentyl acetate is found in banana oil. Esters react
more slowly to nucleophilic acyl substitution than acid chlorides and acid anhydrides.
Amides, like esters are abundant in living organisms – proteins and nucleic acids. Amides are the least
reactive among the carboxylic acid derivatives.
Preparation of Carboxylic Acids
1. Industrial preparation of acetic acid – the most important of all carboxylic acids
2. Industrial preparation of the aromatic acids, benzoic acid and phthalic acid
Carboxylic acids are organic acids. Although not as strong as inorganic acids like hydrochloric acid (HCl),
they still can turn blue litmus paper to red. The carboxylic acids provide the sour taste associated with
foods.
RCOOH + H2O RCOO- + H3O+
The -COOH can be attached to either an alkyl group (RCOOH) or an aryl group (ArCOOH). Whether the
group is aliphatic or aromatic, saturated or unsaturated, substituted or unsubstituted, the properties of
the carboxyl group (-COOH) are essentially the same.
The -OH in carboxylic acids can be replaced by a number pf groups: -Cl, -OCOR (RCOO -), -OR, -NH2 to
yield compounds known as acid chlorides, acid anhydrides, esters, and amides. These compounds are
called functional derivatives of acids, they all contain the acyl group:
An aromatic ring bearing a carboxyl group undergoes electrophilic aromatic substitution characteristic of
a deactivating group
Carboxylic acids are much stronger acids than water. Aqueous hydroxides therefore can convert
carboxylic acids into salts; aqueous mineral acids can readily convert back the salts to carboxylic acids.
Carboxylic acids have high boiling points because of hydrogen bonding just like in alcohols. The extra O
(oxygen) makes the boiling points much higher than in alcohols of comparable molecular weights.
Dicarboxylic Acids
, Acid Chlorides, Acid Anhydrides, Esters and Amides
Acid chlorides are among the most reactive of carboxylic acid derivatives, and can be converted into
other types of compounds by nucleophilic acyl substitution.
Acid anhydrides are typically prepared from acid chlorides by nucleophilic acyl substitution with a
carboxylate ion (RCOO-). The chemistry of the acid anhydrides are the same as the acid chlorides,
although they react more slowly.
Esters are among the most widespread of all naturally occurring compounds. Most simple esters are
pleasant-smelling liquids that are responsible for the fragrant odors of fruits and flowers. Methyl
butanoate is a constituent of pineapple oil while isopentyl acetate is found in banana oil. Esters react
more slowly to nucleophilic acyl substitution than acid chlorides and acid anhydrides.
Amides, like esters are abundant in living organisms – proteins and nucleic acids. Amides are the least
reactive among the carboxylic acid derivatives.
Preparation of Carboxylic Acids
1. Industrial preparation of acetic acid – the most important of all carboxylic acids
2. Industrial preparation of the aromatic acids, benzoic acid and phthalic acid
