Chemistry Reference
In-Depth Information
4.11
The first step has a high activation energy (
E
a
1) and is endothermic because the
aromatic ring is disrupted. The second step has a low activation energy (
E
a
2) and is
exothermic because the aromatic ring is regenerated.
E
a
1
E
a
2
ENERGY
H
E
+
E
+E
+
H
+
+
REACTION COORDINATE
4.12
The electrophile is formed according to the following equilibria, beginning with the
protonation of one sulfuric acid molecule by another:
-
H
O
S OH
+
H
O
S OH
OSO
3
H
+
H
+
H
O
S
OH
-
HO
H
+
+
+
S O
S
OH
Using
+
SO
3
H as the electrophile, we can write the sulfonation mechanism as follows:
H
H
+
H
+
SO
3
H
SO
3
H
SO
3
H
SO
3
H
+
+
_
H
+
SO
3
H
