Download Ester Formation via the Acid Anhydride (Near Neutral Conditions)

Ester Formation via the Acid Anhydride
(Near Neutral Conditions)
[AdN]
acid anhydride
These reactions are often conducted in
presence of a weak base such a pyridine.
The base assists in proton transfer steps.
ester
[pt]
pyridine
[Eβ]
Acid-Catalyzed Ester Formation via Carboxylic Acid
carboxylic
acid
[AdN]
carboxylic
ester
Note that under acidic conditions,
all intermediates are either neutral
or positively charged. All steps are
reversible so formation and
hydrolysis are related as the
forward and backward directions of
these pathways.
For ways to
manipulate the equilibrium see the
link below.
[Eβ]
Manipulating the Equilibrium
http://wps.prenhall.com/wps/media/objects/725/743131/0085f.html
http://www.chemtube3d.com/
Acid-Catalyzed Amide Hydrolysis
Amides are stable functional groups but under forcing conditions can be made to
hydrolyze to carboxylic acids. The acid-catalyzed process is used to hydrolyze
peptides and proteins for amino acid composition and sequence determination.
O
O
R C NH2
+
H OH
+
R C OH
H–Cl
+ NH4Cl
H
H
O
H
H
H
O
R C NH2
H
O
R C NH2
R C OH
H
O
R C NH2
H
+ NH3
elimination
addition
H
O
O
H
–H
H
O
R C NH2
O
H
H
O H
R C N H
H
O H