Chemistry Reference
In-Depth Information
O
O
C
C
CHCl
2
CH
2
Cl
N
N
or
35
34
O
Cl
H
C
N
O
C
N
1
3a
36
H
1
SCHEME 12.15.
Reaction
of
the
benzoyl
nitrene
3a
with
cyclohexane
and
dichloromethane.
17
In dichloromethane,
1
3a
undergoes a C
Cl or C
H insertion reaction with
(Scheme 12.15) with band at 1718 cm
1
solvent to give amide
34
or
35
(
k
gr
¼
10
5
s
1
).
17
In cyclohexane,
1
3a
2.0
undergoes a C
H insertion reaction with
(Scheme 12.15) with strong band at 1680 cm
1
solvent to give amide
36
(
k
gr
¼
10
6
s
1
)
17
in agreement with literature value (1680 cm
1
).
114
The bimolecular
rate constant of the latter reaction was measured in Freon-113 and found to be
(1.8
1.0
10
5
M
1
s
1
(Table 12.7).
18
The absolute rate constants of the bimolecular reactions of
1
3a
0.2)
with methanol,
water,
p
-cyanopyridine, a series of alkenes, as well as halogen anions were also
measured (Table 12.7).
18,100
In the reaction of
1
3a
with halogen anions, a species
involved in the Hofmann rearrangement has been detected by time-resolved infrared
spectroscopy.
100
Note that information on the rate constants of the singlet nitrene bimolecular
reactions is very scarce.
13-15
The data are also available for reactions of a series of
fluoro-substituted aryl nitrenes (
37
-
41
, Scheme 12.16).
115-118
However, different set
of substrates were used to study kinetics of bimolecular reactions of aryl nitrenes and
1
(Tables 12.7 and 12.8). Only water and methanol were used in the study of both
types of nitrenes. Tables 12.7 and 12.8 show that benzoyl nitrene reacts with these
substrates more efficiently than
p
-acetyl-perfluorophenyl nitrene
3a
40
, although the
difference in the rate constants is not significant.
Liu and coworkers
18
studied temperature dependences of the rate of the benzoyl
nitrene reacting with 1-hexene in freone-113 solution and with pentane as the
solvent. The activation energy for the rate constant of the former reaction is
F
F
H
F
F
F
F
F
F
F
F
F
O
O
F
N
C
N
C
N
F
N
H
N
H
3
C
C
3
H
7
N
F
F
H
F
F
F
F
F
F
F
F
F
37
38
39
40
H
41
SCHEME 12.16.
Structures of the fluorosubstituted aryl nitrenes.
