Chemistry Reference
In-Depth Information
Table 7.5
Aromatic Electrophilic Substitution
E
E /
-
H
substitution
Reaction Type
Conditions
Electrophile
Halogenation
Br
2
/FeBr
3
or Cl
2
/FeCl
3
Br or
Cl
Nitration
Conc. HNO
3
/H
2
SO
4
NO
2
Sulfonation
Conc. H
2
SO
4
HSO
3
Friedel-Crafts alkylation
RCl/AlCl
3
R
Friedel-Crafts acylation
RCOCl/AlCl
3
RCO
7.10.2 Aromatic Diazotization
In
Section 7.9.3
, you saw how primary amines react with nitrous acid to give
diazonium salts. Although alkyl examples are mostly too reactive to be useful,
aromatic amines give diazonium salts which are stable at temperatures below
5 °C. These can be used in many different useful reactions. Because aromatic
amines can be easily prepared from nitrobenzenes, this gives the practical syn-
thesis shown in
Figure 7.49
.
FIGURE 7.49
Formation of aromatic diazonium salts.
The main reaction of diazonium salts is by nucleophilic substitution. This
occurs with the loss of a nitrogen molecule.
Table 7.6
shows the prepara-
tion of substituted aromatics which are not available by direct electrophilic
substitution.
Search WWH ::
Custom Search