Carboxylic Acids and Their Derivatives Nucleophilic Addition

106 Pages·2011·1.38 MB·English

Chapter 17
Carboxylic Acids and Their Derivatives

Nucleophilic Addition–Elimination
at the Acyl Carbon
Ch. 17 - 1
1. Introduction
 Carboxylic Acid Derivatives
O O O O
R OH R Cl R O R'
carboxylic acid acid chloride acid anhydride
O
O
R NR'
R OR'
2
ester amide
Ch. 17 - 2
2. Nomenclature and Physical
Properties
 Nomenclature of Carboxylic Acids and
Derivatives
● Rules
 Carboxylic acid as parent
(suffix): ending with “–oic acid”
 Carboxylate as parent (suffix):
ending with “–oate”
Ch. 17 - 3
 Most anhydrides are named by
dropping the word acid from the
name of the carboxylic acid and
then adding the word “anhydride”
 Acid chloride as parent (suffix):
ending with “–oyl chloride”
 Ester as parent (suffix): ending
with “–oate”
 Amide as parent (suffix): ending
with “amide”
 Nitrile as parent (suffix): ending
with “nitrile”
Ch. 17 - 4
Examples

O
O
OCH
OH
3
Ethanoic acid Methyl propanoate
(acetic acid)
O
O O
NH'
O
2
Ethanoic anhydride Ethanamide
(acetic anhydride)
Ch. 17 - 5
Examples

O
O
Cl
O Na
Sodium benzoate Benzoyl chloride
H C C N
3
Ethanenitrile
Ch. 17 - 6
2C. Acidity of Carboxylic Acids
O
H
R O
pK ~ 4-5
a
 Compare
● pK of H O ~ 16
a 2
● pK of H CO ~ 7
a 2 3
● pK of HF ~ 3
a
Ch. 17 - 7
When comparing acidity of organic

compounds, we compare the stability
of their conjugate bases. The more
stable the conjugate base, the stronger
the acid
CH COOH CH CH OH
3 3 2
pK 4.75 16
a
Ch. 17 - 8
O O
+
+ H O + H O
2 3
CH O H CH O
3 3
A B
1 1
+
CH CH O H + H O CH CH O + H O
3 2 2 3 2 3
A B
2 2
Ch. 17 - 9
The conjugate base B is more stable

1
(the anion is more delocalized) than B
2
due to resonance stabilization
O O O
CH O CH O CH O
3 3 3
● Thus, A is a stronger acid than
1
A
2
Ch. 17 - 10