Effect of substituents on the rate of oxidation of anilines with peroxomonosulfate monoanion (HOOSO3-) in aqueous acetonitrile: A mechanistic study

Article abstract of DOI:10.1002/kin.20119

Mechanistic studies on the oxidation of 18 meta-, para-, and ortho-substituted anilines (Ans) by HOOSO₃^- in aqueous acetonitrile medium have been performed. The reaction can be characterized by the experimental rate equation, -d[HSO₅^-]/dt = k[An][HSO₅^-] The addition of p-toluenesulfonic acid (TsOH) retards the reaction. The increase in the reactivity of anilines as the medium is made more aqueous is interpreted. The reaction is enhanced by electron-donating groups on the amine in the series consistent with the rate-limiting nucleophilic attack of the amine on the persulfate oxygen. The proposed mechanism involves the conversion of phenylhydroxylamine to nitrosobenzene in a fast step. The ESR study reveals the absence of free radicals in the reaction. Various attempts have been made to analyze the experimental rate constants in terms of LFER plots. Improved correlations are obtained with σ^- values and the σ^- form of the Yukawa-Tsuno equation.

Full text of DOI:10.1002/kin.20119

Effect of Substituents on the
Rate of Oxidation of Anilines
with Peroxomonosulfate
Monoanion (HOOSO−3 )
in Aqueous Acetonitrile:
A Mechanistic Study
SUBBIAH MEENAKSHISUNDARAM,1 M. SELVARAJU,1 N. M. MADE GOWDA,2
KANCHUGARAKOPPAL S. RANGAPPA3
1Department of Chemistry, Annamalai University, Annamalainagar 608 002, India
2Department of Chemistry, Western Illinois University, One University Circle, Macomb, IL 61455
3Department of Studies in Chemistry, University of Mysore, Mansagangotri, Mysore 570006, India
Received 23 September 2004; accepted 4 May 2005
DOI 10.1002/kin.20119
Published online in Wiley InterScience (www.interscience.wiley.com).
ABSTRACT: Mechanistic studies on the oxidation of 18 meta-, para-, and ortho-substituted ani-
lines (Ans) by HOOSO−3 in aqueous acetonitrile medium have been performed. The reaction
can be characterized by the experimental rate equation,
−d[HSO−5 ]
= k[An][HSO−5 ]
dt
The addition of p-toluenesulfonic acid (TsOH) retards the reaction. The increase in the reactiv-
ity of anilines as the medium is made more aqueous is interpreted. The reaction is enhanced
by electron-donating groups on the amine in the series consistent with the rate-limiting nu-
cleophilic attack of the amine on the persulfate oxygen. The proposed mechanism involves the
conversion of phenylhydroxylamine to nitrosobenzene in a fast step. The ESR study reveals
the absence of free radicals in the reaction. Various attempts have been made to analyze the
Correspondence to: K. S. Rangappa, N. M. Made Gowda; e-mail:
rangappaks@yahoo.com; GN-Made@wiu.edu.
Contract grant sponsor: UGC, New Delhi, India.
Contract grant number: F.12-14/2002(SR-1).
2005 Wiley Periodicals, Inc.
c
ꢀ

650
MEENAKSHISUNDARAM ET AL.
experimental rate constants in terms of LFER plots. Improved correlations are obtained with
σ− values and the σ− form of the Yukawa–Tsuno equation. ꢀ 2005 Wiley Periodicals, Inc. Int J
C
Chem Kinet 37: 649–657, 2005
RESULTS AND DISCUSSION
INTRODUCTION
Afirst-orderdependenceon[HOOSO−3 ]wasevidenced
by the linear semilogarithmic plots of titer versus time.
The first-order plots show curvature after 60% con-
version (Fig. 1) of HOOSO−3 which may be due to
the effect of the product formed. The curvature in the
first-order plots seems to be quite common in the ox-
idations by peroxomonosulfate anion [4–6]. The plot
of kobs as a function of the concentration of aniline
at constant temperature is linear with a zero intercept
(r = 0.998; s = 0.121). The kinetic data are summa-
rized in Table I. The reaction can be characterized by
the rate equation (1),
The oxidation of amines to their oxygenated deriva-
tivesisanimportantindustrialreactionandparticularly,
the reactions of aromatic amines by peroxidic reagents
have received considerable attention. Recently, we em-
barked on the investigation of the kinetics of reaction
involving substituted anilines and peroxomonosulfate
monoanion with the view of probing their mechanisms.
Thus far, the kinetics of oxidation of substituted ani-
lines by HOOSO−3 in basic medium [1] and Ru(III)-
inhibited oxidation in acidic solution [2] (pH ≈ 2.6)
have been examined. Abdul and Maruthamuthu [3]
have reported the oxidation of anilines by HOOSO3−
in aqueous acetic acid medium.
The solvent plays an important role in deciding the
reaction mechanism. In aqueous acetic acid medium
[2,3], no simple Hammett relation was found for the
substituent effects and the lack of LFER was explained.
In aqueous methanol medium [1], the highlight of the
study was the opposite curvatures observed in nonlin-
ear Hammett plots for the rate of decomposition (k) and
the equilibrium constant, K, being concave downward
and upward, respectively. In this study, based on the
kinetic data, we have tried to ascertain the structure-
reactivity relationship in aqueous acetonitrile medium.
In contrast to previously described results, we have
found that, in aqueous MeCN, the conversion of aro-
matic amines (Ans) to nitroso products obeys the linear
free energy relationship (LFER).
−d[HSO−5 ]
= k[An][HSO−5 ]
(1)
dt
The insensitivity of rates to added acrylonitrile as
shown in Table II rules out a mechanism involving ho-
molytic fission of the peroxide bond. The reactivity of
anilines increases as the amount of water in the solvent
is increased (Table I). This probably indicates that the
transition state is more polar than the reactants in the
initial state. A linear plot of log kobs versus D−1 (Fig. 2)
(r = 0.980; s = 0.107) with a negative slope suggests
that there is an involvement of negative ion in the rate-
limiting step. The rate coefficients analyzed with the
Grunwald–Winstein [7] equation (2) (Fig. 3), result in
Figure 1 First-order plots for the reaction of aniline with oxone at 303 K. (a) [Oxone]0 = 0.86 × 10−3 mol dm−3
.
(b) [Oxone]0 = 1.55 × 10−3 mol dm−3
.

EFFECT OF SUBSTITUENTS ON THE RATE OF OXIDATION OF ANILINES
651
Table I Effect of Reactants on the Rate of Oxidation of
Aniline with Oxone at 303 K
Table II Effect of Sodium Perchlorate, TsOH, and
Acrylonitrile on the Reaction Rate at 303 K
103[Oxone]0
102[Aniline]0
102[NaClO4] 102[TsOH] 103[Acrylonitrile] 103kobs
(mol dm−3
)
(mol dm−3
)
Da
103kobs (s−1
)
(mol dm−3
)
(mol dm−3
)
(mol dm−3
)
(s−1
)
0.860
1.15
1.55
2.01
1.15
1.15
1.15
1.15
1.15
1.15
1.15
1.15
1.15
1.15
1.15
4.00
4.00
4.00
4.00
2.00
3.20
4.00
6.00
8.00
14.0
4.00
4.00
4.00
4.00
4.00
44.08
44.08
44.08
44.08
44.08
44.08
44.08
44.08
44.08
44.08
57.00
52.69
42.38
44.08
39.77
1.30
1.25
1.22
1.11
0.58
1.02
1.25
1.91
2.56
5.07
5.61
3.57
2.02
1.25
0.360
–
2.64
5.00
7.90
–
–
–
–
–
0.00
0.56
1.12
2.24
–
–
–
–
–
–
–
–
–
–
5.0
10.0
16.0
20.0
1.25
1.50
1.72
1.90
2.13
1.25
0.79
0.64
0.49
1.23
1.22
1.20
1.25
10.20
–
–
–
–
–
–
–
–
–
–
–
[Aniline]0 = 4.00 × 10−2 mol dm−3
;
[Oxone]0 = 1.15 ×
10−3 mol dm−3 Acetonitrile: H2O = 80:20 (v/v).
a Dielectric constant values are calculated from the values of pure
solvents.
D2O has no significant effect on the rate of conversion
as shown in Table III. The lack of solvent isotope effect
excludes the rate-controlling participation of water, as a
proton transfer agent [10]. In the present investigations,
since the solvent composition variation is very small,
a proton transfer process is not completely ruled out.
p-Toluenesulfonic acid (TsOH) retards the reactiv-
ity of anilines significantly (Table II). The pseudo-first-
order rate constants decrease from 1.25 × 10−3 s−1 to
0.49 × 10−3 s−1 by adding 2.24 × 10−2 mol dm−3 of
TsOH. This observation suggests that the free avail-
ability of the aniline lone pair facilitates the oxidation.
It appears that the ionization state of the amine is im-
portant. It seems quite unlikely that the addition of acid
(ca. 2 × 10−2 mol dm−3) is changing the nature of the
oxidizing species.
a curvature
log k = log ko + mY
(2)
Here Y is the quantity which measures the ioniz-
ing power of the solvent (YOTS values are used) and
m ≈ 0.4. Less satisfactory fits with Eq. (2) suggested
an SN2 type reaction [8]. The small value of m cer-
tainly suggests that the charge separation is not large
in the passage from the ground state to the transi-
tion state. The small m value is comparable with the
values observed in bimolecular substitution reactions
[7,9].
The change in ionic strength (Table II) showed a
small increase in kobs with increase in the ionic strength.
Figure 2 A plot of log kobs versus 1/D.

652
MEENAKSHISUNDARAM ET AL.
Figure 3 A plot of log kobs versus YOTS
.
The ρ values suggest an electron-deficient transition
state.
Effect of Substituents
Substituent effects are used as probes of the reaction
mechanisms of aromatic compounds. The effect of sub-
stituents on aniline reactivity has been investigated
by employing 18 meta-, para-, and ortho-substituted
anilines. Generally, from the results it is evident that
electron-releasing substituents accelerate the rate while
electron-withdrawing ones retard the reactivity. The
rate coefficients and activation parameters evaluated
from the Eyring plots of ln (k/T ) versus 1/T are listed
in Table IV.
The Hammett equation is an empirical relationship
for correlating structure and reactivity. The rate coeffi-
cients of the members of the amine series are linearly
related to the respective σ values. Experimental data
are better correlated with the Hammett ρσ relation-
ship (Fig. 4) (r = 0.949; s = 0.256) rather than the
Brown–Okamoto ρσ+ relationship (Fig. 5) (r = 0.923;
s = 0.313) for the substituents in the meta- and para-
positions of the benzene ring. In the case of para-
substituents, only the correlation of the rate constants
with σ/σ+ is much better (r ≈ 0.977; s ≈ 0.218).
The reaction constant values are listed in Table V.
A slight deviation is observed in the Hammett plot
for the m-NO2 substituent (no. 11). Instead of the
Hammett value, if the σR− value (0.46) based on the
ionization of anilinium ions in water at 25◦C is applied,
then the m-NO2 substituent falls on the Hammett line.
We have tried to express the kinetic data in terms of
Yukawa–Tsuno equation [11], Eq. (3), taking into ac-
count an exalted resonance contribution
log(k/ko) = ρ(σ + r+ꢀσR+)
(3)
where r+ is a constant depending on the resonance ef-
fect in the reaction, and ꢀσR+ measures the capacities of
substituents to supply electrons by resonance. Figures 6
and 7 show results with r+ equal to 0.074 and 0.254,
respectively. The positive r+ value shows that the tran-
sition state is stabilized by additional resonance be-
tween positively charged reaction center and electron-
releasing substituents. As is clear in these figures the
correlation does not improve much (r = 0.950; s =
0.259). The effect of the para-substituents on the first-
order rate coefficients is well described by Yukawa–
Tsuno equation as shown in Table VI (R ≈ 0.988;
s ≈ 0.144).
The ratio of rate coefficients of para- and ortho-
substituted anilines is >1 (Table VII). This observation
suggests a significant steric hindrance in the HOOSO3−
oxidations of anilines. However, the general adherence
to the Hammett equation for the ortho-substituted ani-
lines listed shows that the steric effect is not too large.
These contrasting observations reflect small but signif-
icant steric effect in the reactivity. Analysis of the rate
coefficients (at 303 K) with Charton’s equation [12]
further reveals that the coefficient of the steric term is
Table III Effect of D2O on the Reaction Rate
% Solvent
Acetonitrile : H2O : D2O
103kobs (s−1
)
80 : 20 : 00
80 : 15 : 05
80 : 10 : 10
80 : 05 : 15
1.25
1.23
1.22
1.20
[Aniline]0 = 4.00 × 10−2 mol dm−3
;
[Oxone]0 = 1.15 ×
10−3 mol dm−3
.

EFFECT OF SUBSTITUENTS ON THE RATE OF OXIDATION OF ANILINES
653
Table IV Rate Constants and Activation Parameters for the Oxidation of Anilines with Oxone in Aqueous Acetonitrile
Medium
kobs103 (s−1
)
ꢀH=
(kJ mol−1
−ꢀS=
ꢀG=(30◦)
No.
Aniline
20◦C
30◦C
40◦C
)
(J K−1 mol−1
)
(kJ mol−1
)
r
s
1
2
3
4
5
6
7
8
H
0.67
1.20
2.27
0.34
0.30
0.006
0.03
0.63
0.43
0.07
0.05
0.46
1.53
0.06
0.02
0.01
0.03
0.004
1.25
2.11
4.28
0.54
0.52
0.01
0.05
1.16
0.72
0.13
0.10
0.71
3.15
0.11
0.04
0.03
0.04
0.007
1.97
3.97
7.83
1.25
0.81
0.02
0.13
1.95
1.12
0.25
0.16
1.43
5.96
0.19
0.08
0.05
0.09
0.01
38.2
42.7
44.6
59.9
35.5
40.0
59.0
40.9
33.6
48.1
42.9
40.3
49.2
43.6
43.0
51.6
44.2
40.1
175.0
155.2
143.2
110.0
191.1
207.9
132.0
166.7
194.5
161.0
181.0
171.6
130.7
177.4
186.3
162.9
182.3
212.0
93.0
89.7
88.0
93.2
93.4
103.0
99.0
91.4
92.5
96.8
97.7
92.3
88.8
97.3
99.5
100.9
99.4
104.3
0.998
0.999
0.999
0.999
0.999
0.997
0.994
0.999
0.999
0.999
0.991
0.986
0.999
0.998
0.991
0.998
0.995
0.999
0.051
0.042
0.005
0.021
0.022
0.017
0.081
0.028
0.019
0.018
0.105
0.122
0.017
0.004
0.106
0.061
0.078
0.030
p-CH3
p-OCH3
p-Cl
p-Br
p-NO2
p-COOH
m-CH3
m-OCH3
m-Cl
m-NO2
o-CH3
o-OCH3
o-F
o-Cl
o-I
o-COOH
o-NO2
9
10
11
12
13
14
15
16
17
18
[Amine]0 = 4.00 × 10−2 mol dm−3, [Oxone]o = 1.15 × 10−3 mol dm−3
.
small but significant (Eqs. (3) and (4)).
Also, the localized effect predominance is clearer from
the high value of the σI coefficient.
log k = ασI + βσR + ϕν + h
(4)
Mechanism
log k = −2.18σI − 0.81σR − 0.5ν − 2.92 (5)
(100R = 90; SE = 0.53, n = 8)
The peroxomonosulfate anion exists [13] as HSO−5 in
polar solvents. Many peroxyanions are effective nucle-
ophiles, while HSO−5 is a very weak nucleophile [9].
In spite of the fact that free radicals can arise from
(σR−values used in the correlation;
−NO2 and −COOH planar)
Figure 4 The Hammett plot (numbered as in Table IV).

654
MEENAKSHISUNDARAM ET AL.
Figure 5 Brown–Okamoto plot (numbered as in Table IV).
the facile homolysis of the oxygen oxygen bond [14],
an ionic mechanism is favored in certain reactions in-
volving oxidations by peroxides. In the present inves-
tigation, no observed polymerization in the presence
of acrylonitrile rules out a free radical process. The
ESR study indicates the absence of free radical pro-
cesses during and after the reaction. Negative reaction
constant (ρ) values suggest a bimolecular process that
involves the nucleophilic attack of aniline on the per-
oxidic oxygen. A type of transition state with a fully
developed positive charge on the nitrogen is quite con-
sistent with ρ ≈ −2.2 for this conversion of anilines.
H
|
ꢀ
ꢁ
K
ꢀ
ꢁ
C6H5NH2 + O O SO−
+ · · · OH · · · SO2−
H
¨
N
3
4
|
(Forward step rate limiting)
(C1)
(6)
k2
C1
C H NHOH + HSO−
(7)
−→
6
5
4
Fast
HSO−5
−−−→
Fast
C H NHOH
C H NO + H O + HSO−
(8)
6
5
6
5
2
4
Table V Reaction Constant Values at Different
Temperatures
The transition state C1 with a positive charge on nitro-
gen is consistent with significant kinetic electronic sub-
stituent effects. The proposed mechanism is well sup-
ported by the observed stoichiometry of 2:1 for HSO−5 :
amine.
Correlation
Temperature (◦C)
ρ
n
ρσ
20
30
40
20
30
40
20
30
40
20
30
40
20
30
40
20
30
40
−2.27
−2.21
−2.27
−2.19
−2.15
−2.12
−1.60
−1.57
−1.56
−2.49
−2.48
−2.42
−1.72
−1.71
−1.69
−1.69
−1.68
−1.64
17a
Negative entropies of activation are as expected for
a bimolecular reaction [15]. It also implies highly or-
ganized or rigid transition state. The linearity of the
plot of ꢀH= versus ꢀS= is a criterion for validity of
the Hammett equation [16]. As is clear in the isoki-
netic plot of Fig. 8, there is a considerable scattering of
points. Exner [17] criticized the validity of such linear
correlations between ꢀH= and ꢀS= as these quanti-
ties are dependent on each other. The linear relation-
ship in the Exner plots log kobs(40◦C) versus log kobs
(30◦C) (Fig. 8, r ≈ 0.998; s ≈ 0.601) supports a simi-
lar mechanism for all the anilines listed. The isokinetic
temperature β was calculated using the relation [17],
ρσ
11b
11b
7c
ρσ+
ρσ
ρσ+
ρσ−
7c
7c
T1T2(1 − f )
ꢀ =
(T1 − T2 f )
a o-COOH not included in correlation since σo∗ values are not
available.
b Effect of meta- and para-substituents in the correlation.
c Effect of para-substituents only in the correlation.
where f is slope of the Exner plot. The β value is found
to be less than the experimental temperature (<200 K).

EFFECT OF SUBSTITUENTS ON THE RATE OF OXIDATION OF ANILINES
655
Figure 6 Yukawa–Tsuno plot (numbered as in Table IV).
Figure 7 Yukawa–Tsuno plot (numbered as in Table IV).
ꢀ
Figure 8 Exner plot (numbered as in Table IV). m− and p−substituents. ꢂ o− substituent.

656
MEENAKSHISUNDARAM ET AL.
Table VI Yukawa–Tsuno Analysis
Substituent
Constants
No.
1
Temp. (◦C)
100R
SE
ψ
f
n
20
30
40
20
30
40
94.88
94.96
95.82
95.02
95.11
0.278
0.270
0.242
0.290
0.283
0.252
0.370
0.368
0.336
0.372
0.369
0.334
0.166
0.165
0.190
0.175
0.174
0.156
11
11
11
10
10
10
σ, (σ+ − σ)
2
σ0, (σ+ − σ0)
96.02
para-Substitutents only
97.33
20
30
40
20
30
40
20
30
40
20
30
40
0.262
0.226
0.220
0.280
0.244
0.226
0.098
0.087
0.069
0.084
0.087
0.070
0.304
0.265
0.263
0.325
0.287
0.271
0.114
0.102
0.083
0.097
0.102
0.085
0.167
0.145
0.144
0.179
0.157
0.148
0.061
0.055
0.044
0.052
0.055
0.045
7
7
7
7
7
7
7
7
7
7
7
7
3
4
5
6
σ, (σ+ − σ)
σ0, (σ+ − σ0 )
σ, (σ− − σ)
97.96
98.00
96.94
97.62
97.88
99.63
99.70
99.80
99.73
99.70
99.80
σ0, (σ− − σ0 )
Since β–T is negative, the reaction is believed to be
entropy controlled. The ꢀS= values are similar to the
corresponding data measured for typical reactions in-
volving oxygen transfer [2,18].
ics, contrasting kinetic behaviors are observed for the
effect of substituents on the formation constant (K) of
the radical cation intermediate, PhNH2, and its rate of
decomposition (k). Ru(III)-inhibited oxidation of ani-
lines by HSO−5 [2] to nitroso products in acidic solution
(pH ≈ 2.6) resulted in the formation of a concave up-
ward Hammett plot with a rate minimum. In contrast to
previously described results, in the present investiga-
tion, the aniline–HOOSO−3 reaction system in aqueous
MeCN medium obeys the Hammett and Yukawa rela-
tionships. It appears the contrasting effect of the sub-
stituents in the conversion of anilines to nitroso prod-
ucts depends on the nature of the solvent. The kinetics
of oxidation of anilines [19] by H2PO−5 in aqueous ace-
tonitrile medium at pH 5.4 revealed that all the meta-
and para-substituted anilines except the p-nitro one are
on the Hammett line. The rates of ortho-substituents,
which are consistently retarded, form a separate line.
Substituent effects in the conversion of anilines to
nitroso products are different in various solvents. Ab-
dul and Maruthamuthu in their recent kinetic study [3]
on the effect of substituents on the rate of the reac-
tion between aromatic amines and peroxomonosulfate
ion in aqueous acetic acid medium have reported that
both electron-releasing and withdrawing groups retard
the reactivity. No simple Hammett relation is found
for the substituent effects. The results are explained by
the formation of a transition complex of cyclic nature.
Effect of substituents on the reactivity of anilines by
HSO−5 [1] revealed interesting results in basic medium
(pH > 11). In a typical Michaelis-Menten type kinet-
Table VII The Ratio of Rate Coefficients of para and
ortho Substituents
EXPERIMENTAL
kp/ko
The reactions were carried out in 80% aqueous ace-
tonitrile (v/v) medium. All the solutions were kept in
a thermostat at constant temperature controlled using
a Gallenkemp thermostat to an accuracy of 0.1◦. The
measurements were made between 293 K and 313 K.
The required volumes of these solutions for each run
were mixed, and 2 mL aliquots of the reaction mix-
ture were pipetted out at convenient time intervals and
Substituent
20◦C
30◦C
40◦C
CH3
OCH3
Cl
COOH
NO2
2.61
1.48
13.80
0.96
2.97
1.36
12.56
1.16
2.78
1.31
15.10
1.46
1.50
1.57
1.82

EFFECT OF SUBSTITUENTS ON THE RATE OF OXIDATION OF ANILINES
657
quenched in 10 mL of 2% potassium iodide solution
and the liberated iodine was titrated against standard
thiosulfate to a starch end point.
3. Abdul, J. A.; Maruthamuthu, P. J Indian Chem Soc 1998,
75, 368.
4. Ramachandran, M. S.; Vivekanandam, T. S. J Chem Soc,
Perkin Trans 2 1984, 1341.
5. Ramachandran, M. S.; Vivekanandam, T. S. J Chem Soc,
Perkin Trans 2 1984, 1345.
Stoichiometry and Product Analysis
6. Ramachandran, M. S.; Vivekanandam, T. S. Tetrahedron
1984, 40(23), 4929.
7. Grunwald, E.; Winstein, S. J Am Chem Soc 1948, 70,
846.
8. Shorter, J. Correlation Analysis of Organic Reactivity;
Research Studies Press: Chichester, UK, 1982; p. 139.
9. Karunakaran, K.; Gurumurthy, R.; Elango, K. P. J Indian
Chem Soc 1998, 75, 297.
10. Ruff, F.; Kucsman, A. J Chem Soc, Perkin Trans 2 1985,
683.
11. Yukawa, Y.; Tsuno, Y. Bull Chem Soc Jpn 1959, 32, 971.
12. Aslam, M. H.; Burden, A. G.; Chapman, N. B.; Shorter,
J.; Charton, M. J Chem Soc, Perkin Trans 2 1981, 500.
13. Ramachandran, M. S.; Vivekanandam, T. S.;
Arunachalam, V. Bull Chem Soc Jpn 1986, 59, 1549.
14. Kerr, J. A. Chem Rev 1966, 66, 465.
15. Frost, A.; Pearson, R. G. Kinetics and Mechanism;
Wiley: New York, 1961; p. 144.
The stoichiometric runs carried out in the presence of
excess of oxone at 30◦C, revealed that two moles of
the oxidant react with 1 mole of aniline. The reaction
between oxone and aniline under the kinetic condi-
tions gave an insoluble residue after standing for 3 h.
The recrystallised (in alcohol) residue was found to be
nitrosobenzene as established by determining the melt-
ing point (mp 60–61◦C), which corresponds to the liter-
ature value. Similar nitroso products were obtained for
the meta-, para-, and ortho-substituted anilines. The
products were confirmed by TLC, m.p., and NMR data
in comparison with the authentic sample.
BIBLIOGRAPHY
1. Meenakshisundaram, S. P.; Sockalingam, R. M. Collect
Czech Chem Commun 2001, 66, 897.
16. Harry, S. H.; Harmuth, C. M. J Am Chem Soc 1964,
2909.
2. (a) Meenakshisundaram, S. P.; Sathiyendiran, V. J Chem
Res (S) 2001, 10–11; J Chem Res (M) 2001, 0115–0132;
(b) Rangappa, K. S. J Phys Org Chem 2001, 14, 684–
690; J Phys Org Chem 2001, 14, 716–724.
17. Exner, O. Nature 1964, 201, 488.
18. Modena, G.; Maioli, J. Gazz Chim Ital 1957, 87, 1306.
19. Panda, A. K.; Mahapatra, S. N.; Panigrahi, G. P. J Org
Chem 1981, 46, 4000.