Chemistry Reference
In-Depth Information
e.
Electrophile; sulfuric acid is a proton donor.
f.
Electrophile; the aluminum has only a sextet of electrons. It is electron-
deficient and can accept an electron pair.
g.
Nucleophile; the negatively charged oxygen reacts with electrophiles.
3.44
C H
+
C H
H
O
H
H
+
C H
C H
The oxygen
carries a formal
+1 charge
H
+
-
OH
+
O
H
H
In the first step, the proton adds in such a way as to give the tertiary carbocation
intermediate.
a.
3.45
C
3
C
C
3
C
C
3
C
+
+
H
protonation
of C-2
H
protonation
of C-1
C H
C H
+
C H
C H
1
C H
C H
2
+
H
1° carbocation
3° carbocation
The 3
o
carbocation is more stable than the 1
o
carbocation.
b.
Both protonations are endothermic, but the protonation which gives the
tertiary carbocation is less endothermic, and thus energetically more
favorable than the reaction leading to the primary carbocation.
1° carbocation
3° carbocation
ENERGY
+H
+
(C H)
2
CCH
REACTION COORDINATE
The tertiary carbocation then reacts with water to give
(CH
3
)
3
C
−
OH (2-methyl-2-propanol).
