Oxidation of arylamines, arylhydroxylamines and other derivatives 153
Table 4.2 Oxidation of arylamines with peroxycarboxylic acids
NH 2
NO 2
NH 2
O 2 N NO 2
NO 2
NH 2
CH 3 CO 3 H
OCH 3
NH 2
SO 3 H
NH 2
CH 3
NH 2
NH 2
NH 2
NO 2
CF 3 CO 3 H
NO 2
NO 2
NO 2
O 2 N NO 2
NO 2
NO 2
OCH 3
NO 2
SO 3 Na
NO 2
CH 3
NO 2
NO 2
NO 2
NO 2
Entry Substrate Conditions Product Yield (%)
25163
82164
maleic anhydride,
90 % H 2 O 2 , CH 2 Cl 2
(HO 2 C-CH=CH-CO 3 H)
87166
74165
CHCl 3 , H 2 SO 4 (cat),
Ac 2 O, 90 % H 2 O 2 , reflux
1
2
4
3
5a
5b
6a
6b
7 92168
90 % H 2 O 2 , (CF 3 CO) 2 O,
CH 2 Cl 2 , reflux^86
167
89167
92167
81167
(66)
(68)
(72)
(70)
(74)
(76)
(78)
(67)
(69)
(73)
(71)
(75)
(77)
(79)
90 % H 2 O 2 , CF 3 CO 2 H,
CH 2 Cl 2 , reflux
90 % H 2 O 2 , (CF 3 CO) 2 O,
CH 2 Cl 2 , reflux
90 % H 2 O 2 , CF 3 CO 2 H,
CH 2 Cl 2 , reflux
- 30 % H 2 O 2 , CH 3 CO 2 H
70–75 °C - NaHCO 3
These solutions readily oxidize nitroanilines to the corresponding dinitrobenzenes but are
unable to oxidize amines of lower basicity like the dinitroanilines.^163 ,^164 Peroxyacetic acid
is well suited for the oxidation of arylamines containing strong electron-donating groups
(Table 4.2, Entry 2). Stronger oxidants like peroxytrifluoroacetic acid rapidly degrade such
substrates and give rise to various phenolic by-products. Peroxyacetic acid is also the reagent
of choice for the oxidation of some condensed ring arylamines (Table 4.2, Entry 1).^163
The reagent prepared from the reaction of 30 % hydrogen peroxide with glacial acetic acid
also contains peroxyacetic acid but the main product of arylamine oxidation is usually the
corresponding nitroso compound.^169 ,^170 On heating with an excess of this reagent the nitro
compound is usually obtained.^165 ,^169