The reactions of O-(4-nitrophenyl) S-aryl dithiocarbonates with anilines: Effects on the relative nucleofugality

Article abstract of DOI:10.1002/poc.3818

Kinetic and high-performance liquid chromatography studies were investigated for the reactions of S-phenyl, S-(4-chlorophenyl), and S-(4-nitrophenyl) O-(4-nitrophenyl) dithiocarbonates with anilines. These were performed in the presence of 0.1M borate buffer in 44?wt% aqueous ethanol. For reactions of the 3 substrates, the mechanism is stepwise with 2 tetrahedral intermediates, one zwitterionic (T^±), and the other anionic (T^?), where the intermediate T^? is formed by proton transfer from T^± to the borate buffer. The nonleaving group is not passive, playing an important role in the relative nucleofugality of the groups, which depend largely on its electron withdrawing capability. The nucleofugacity of 4-nitrophenolate ion and of 4-nitrophenylthiolate from the same tetrahedral intermediate is similar, despite the differences in their basicities (3 pK_a units). In the reactions of S-(4-nitrophenyl) O-(4-nitrophenyl) dithiocarbonate, the change of nucleophile from pyridines (only 4-nitrophenolate ion is nucleofuge) to anilines (2 nucleofuges) shows that the nature of the amine impacts on the relative nucleofugality of groups.

Full text of DOI:10.1002/poc.3818

Received: 19 November 2017
DOI: 10.1002/poc.3818
Revised: 29 December 2017
Accepted: 8 January 2018
S P E C I A L I S S U E A R T I C L E
The reactions of O‐(4‐nitrophenyl) S‐aryl dithiocarbonates
with anilines: Effects on the relative nucleofugality
José G. Santos1
| Marcela Gazitúa2
1 Facultad de Química, Pontificia
Universidad Católica de Chile, Casilla 306,
Santiago 6094411, Chile
2 Centro de Química Médica, Facultad de
Medicina, Clínica Alemana Universidad
del Desarrollo, Santiago 7710162, Chile
Abstract
Kinetic and high‐performance liquid chromatography studies were investigated
for the reactions of S‐phenyl, S‐(4‐chlorophenyl), and S‐(4‐nitrophenyl) O‐
(4‐nitrophenyl) dithiocarbonates with anilines. These were performed in the
presence of 0.1M borate buffer in 44 wt% aqueous ethanol. For reactions of
the 3 substrates, the mechanism is stepwise with 2 tetrahedral intermediates,
one zwitterionic (T ), and the other anionic (T−), where the intermediate T−
is formed by proton transfer from T to the borate buffer. The nonleaving group
is not passive, playing an important role in the relative nucleofugality of
the groups, which depend largely on its electron withdrawing capability. The
nucleofugacity of 4‐nitrophenolate ion and of 4‐nitrophenylthiolate from the
same tetrahedral intermediate is similar, despite the differences in their basic-
ities (3 pKa units). In the reactions of S‐(4‐nitrophenyl) O‐(4‐nitrophenyl)
dithiocarbonate, the change of nucleophile from pyridines (only 4‐
nitrophenolate ion is nucleofuge) to anilines (2 nucleofuges) shows that the
nature of the amine impacts on the relative nucleofugality of groups.
Correspondence
José G. Santos, Facultad de Química,
Pontificia Universidad Católica de Chile,
Casilla 306, Santiago 6094411, Chile.
Email: jgsantos@uc.cl
Funding information
ICM‐MINECON; FONDECYT, Grant/
Award Numbers: 1130044 and 1160271;
RC‐130006‐CILIS
KEYWORDS
diaryl dithiocarbonates, nucleofugality
1 | INTRODUCTION
zwitterionic tetrahedral intermediate (T ). Depending
on the basicity and nature of the amine, the T decom-
The kinetics and mechanisms of the aminolysis of alkyl
aryl and diaryl carbonates and some of their sulfur
derivatives, such as O‐alkyl S‐aryl dithiocarbonates, are
well documented.[1–7] On the other hand, the mecha-
nism of the aminolysis of O‐aryl S‐aryl dithiocarbonates
has been extensively studied by us (Scheme 1).[8] The
reaction of a series of secondary alicyclic (SA) amines
with O‐phenyl S‐(4‐nitrophenyl) dithiocarbonate (1), O‐
(4‐methylphenyl) S‐(4‐nitrophenyl) dithiocarbonate (2),
and O‐(4‐chlorophenyl) S‐(4‐nitrophenyl) dithiocarbonate
(3),[8a, b] the pyridinolysis[8c] and the anilinolysis[8e] of 2
and 3, all occur by a stepwise mechanism. This mecha-
nism is initiated by the nucleophilic attack of amine to
the thiocarbonyl group, leading to the formation of a
poses directly to products expelling the nucleofuge or
can be deprotonated forming an anionic tetrahedral
intermediate (T−) and then expelling the nucleofuge.[8]
The deprotonating agent of T can be a second amine
molecule or an external buffer.[8b, e] If the agent is a sec-
ond amine molecule, plots of kobs versus free amine con-
centration at constant pH are nonlinear upwards, but if
the proton transfer is to the external buffer, these plots
are linear.[8b, e]
In all the studied reactions of dithiocarbonates 1 to 3
with SA amines,[8a, b] pyridines,[8c] and anilines,[8e] the
S‐(4‐nitrophenyl) group was the nucleofuge; this behavior
was explained considering the lower pKa of the conjugated
acid of S‐(4‐nitrophenyl) compared with phenol as a
J Phys Org Chem. 2018;e3818.
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SANTOS AND GAZITÚA
nonleaving group in the substrates. On the other hand, in
the pyridinolysis reaction of O‐(4‐nitrophenyl) S‐phenyl
dithiocarbonate 4 and O‐(4‐nitrophenyl) S‐(4‐nitrophenyl)
dithiocarbonate 5,[8d] the nucleofuge was the 4‐
nitrophenolate ion in spite of the fact that the pKa of
4‐nitrophenol is greater than that of benzenethiol and
that of 4‐nitrobenzenethiol. Apparently, the basicity is
not the exclusive reason to determine the nucleofugality
of groups, and the nonleaving group probably plays an
important role in this behavior. More recently, the kinetic
study of 5 with SA amines showed that the mechanism is
concerted and both groups attached to the thiocarbonyl
group are nucleofuges.[8f]
at 25.0 0.1°C and an ionic strength of 0.2M (maintained
with KCl). The reactions were followed in a wavelength
range between 300 and 500 nm and studied under at least
10‐fold excess of amine over the substrate. The initial con-
centration of the substrate was 2.5 × 10−5M. Under these
conditions, pseudo–first‐order rate coefficients (kobs) were
found throughout and the kinetics were measured for at
least 5 half‐lives, following the formation of the 4‐
nitrophenoxide ion. The pH was maintained constant by
using a 0.1M borate buffer. The kobs values obtained and
the experimental conditions for the studied reactions are
detailed in Tables S1 to S3.
To shed more light on the mechanisms and selectivity
of the anilinolysis of O‐aryl S‐aryl dithiocarbonates, in
this work, we report both a kinetic and an analytic
study of the reactions of 4, 5, and O‐(4‐nitrophenyl)
S‐(4‐chlorophenyl) dithiocarbonate (6) with a series of
anilines. A comparison between the kinetic results and
product analyses obtained in this work and with other
substrates previously published will permit to determine
the influence of the amine and of the nonleaving group
on the nucleofugality of the potential leaving groups in
these reactions.
2.3 | Product studies
2.3.1 | UV‐vis analysis
For all the reactions, 4‐nitrophenoxide anion was identi-
fied as one of the products. This was achieved by compar-
ison of the UV‐vis spectra after the reactions end with
those of an authentic sample of 4‐nitrophenol, under the
same reaction conditions.
2.3.2 | High‐performance liquid chroma-
tography analysis
These were performed by high‐performance liquid
chromatography (HPLC) with a diode array detector,
provided with LiChroCART 250‐4 HPLC‐RP‐18e (5 μm),
mobile phase of 50% CH3CN/acetate buffer (0.01M,
pH 5.0), and flow rate of 1.2 mL/min. 4‐Nitrophenol,
benzenethiol, and 4‐chlorobenzenethiol were identified
by comparison of their spectra and retention times (r.t.)
with those of authentic samples. Thionocarbonates and
dithiocarbonates were identified through comparison of
the spectra and r.t. of the products obtained in the reac-
tions of 4‐nitrophenyl thionochloroformate, phenyl
dithiochloroformate, and 4‐chlorophenyl dithiochloro-
formate with aniline.
The reactions of 4 with aniline show the presence of 4‐
nitrophenol (r.t. = 3.1 min, λ = 330 nm) and phenyl aniline
dithiocarbamate (r.t. = 5.4 min, λ = 280 nm). The
presence of O‐(4‐nitrophenyl) aniline thionocarbamate
(r.t. = 6.5 min, λ = 270 nm) was not observed.
The reactions of 6 with aniline show the presence of
4‐nitrophenol (r.t. = 3.1 min, λ = 330 nm) and 4‐
chlorophenyl aniline dithiocarbamate (r.t. = 5.1 min,
λ = 260 nm). Aniline O‐(4‐nitrophenyl) thionocarbamate
(r.t. = 6.5 min, λ = 270 nm) was not detected.
SCHEME 1 Structure of a series of diaryl dithiocarbonates
2 | MATERIALS AND METHODS
2.1 | Materials
Anilines were purified by recrystallization or distillation.
Dithiocarbonates 4 and 5 were prepared as described.[8d]
Dithiocarbonate 6 was prepared in the same way and
presents the following analytical properties:
1H‐NMR (400 MHz, CDCl3) δ (ppm): 7.27 (d, 2H,
J = 9.2 Hz); 7.46 (d, 2H, J = 8.8); 7.53 (d, 2H,
J = 8.4 Hz); 8.30 (d, 2H, J = 9.2 Hz). 13C‐NMR
(100 MHz, CDCl3) δ (ppm): 123.7; 125.8; 128.5; 130.4;
137.0; 137.8; 146.4; 158.9; 212.1.
Elem. Anal. Calcd. for C13H8ClNO3S2: C: 47.93; H: 2.48;
N: 4.30; S: 19.68. Found: C: 48.10; H: 2.08; N: 4.01; S: 18.31.
The HPLC study of the reactions of 5 with aniline
(Figure 1) shows the presence of 4‐nitrophenol
(r.t. = 3.1 min, λ = 330 nm), O‐(4‐nitrophenyl) aniline
2.2 | Kinetic measurements
The kinetics of the reactions were analyzed through a
diode array spectrophotometer in 44 wt% ethanol‐water,
dithiocarbamate (r.t. = 5.2 min, λ = 270 nm),

SANTOS AND GAZITÚA
3 of 7
In the case of the HPLC study for the reactions of 6,
results show that 4‐nitrophenol and aryl aniline dithiocar-
bamate were the products, indicating that in these reac-
tions, the 4‐nitrophenolate ion is the main nucleofuge.
It is important to point out that although traces of
4‐chlorobenzethiol and of O‐(4‐nitrophenyl) aniline
thionocarbamate (less than 1%) were found in this
analysis, they could be due to the expulsion of
4‐chlorobenzenethiolate; however, in this study, we will
consider that 4‐nitrophenolate ion is the main nucleofuge.
FIGURE 1 High‐performance liquid chromatography analysis of
the reaction of 5 with aniline (from 0 to 37 min, at λ = 316 nm). A, 4‐
nitrophenol. B, Dimer of 4‐nitrobenzenethiol. The insert is a small
part of the same chromatogram (4.5‐6.5 min at λ = 270 nm). C, 4‐
Nitrobenzenethiol aniline dithiocarbamate. D, 4‐Nitrophenyl
aniline thiocarbamate
3.2 | Kinetics and mechanism
For all the studied reactions, pseudo–first‐order rate con-
stants (kobs) were obtained under aniline excess. These
rate constants and the experimental conditions are found
in Tables S1 to S3.
In some of the studied anilinolysis, it has been
described that anilines play 2 roles, one as nucleophile
and the other as base.[9] To preclude the participation of
a second aniline molecule as deprotonating agent of the
possible tetrahedral intermediate formed in a stepwise
mechanism, the reactions were performed in the presence
of 0.1M borate buffer.
O‐(4‐nitrophenyl) aniline thionocarbamate (r.t. = 6.5 min,
λ = 270 nm), and the dimer of 4‐nitro benzenethiolate
(r.t. = 34 min, λ = 330 nm).
3 | RESULTS AND DISCUSSION
3.1 | Chromatographic study of the
anilinolysis reaction
Under these experimental conditions, plots of kobs
against free amine concentration [N] were linear
(Equation 1). In Equation 1, k0 and kN are solvolysis and
the nucleophilic rate constants.
Figure 1 shows the HPLC results for the reaction of 5 with
aniline. The presence of 4‐nitrophenol (first chromato-
graphic peak, at r.t. = 3.1 min) and the dimer of
4‐nitrobenzenethiol (second chromatographic peak, at
r.t. = 34 min) can be observed. This result suggests that
in this reaction, both groups linked to the thiocarbonyl
moiety of 5 are nucleofuges. This is confirmed by the pres-
ence of the 2 aniline carbamates as products (see the insert
of the Figure 1).
The HPLC study of the reactions of 4 shows that
4‐nitrophenol and the phenyl aniline dithiocarbamate
were the products, indicating that in these reactions, only
the 4‐nitrophenolate ion is the nucleofuge.
kobs ¼ k0 þ kN½Nꢀ:
(1)
In all cases, kN[N] ≫ k0; therefore, the solvolysis reac-
tion is disregarded. Table 1 exhibits a summary of the kN
values obtained for the anilinolysis of dithiocarbonates
4 to 6.
Figure 2 shows the Brønsted plots obtained. The kN
values of Table 1 as well as those of the pKa of the
conjugate acids of the anilines were statistically corrected
TABLE 1 kN values obtained for the reactions of S‐phenyl O‐(4‐nitrophenyl) dithiocarbonate (4), S‐(4‐nitrophenyl) O‐(4‐nitrophenyl)
dithiocarbonate (5), and S‐(4‐chlorophenyl) O‐(4‐nitrophenyl) dithiocarbonate (6) with anilines at 25°C, ionic strength 0.2M (KCl), and borate
buffer 0.1M, in 44 w/w% ethanol‐water
102 kN/s−1 M−1
Amine
pKa
4
5
6
1,4‐Phenylenediamine
6.45
…
233
53
5
2
220
50
7
1
4‐Methoxyaniline
4‐Methylaniline
Aniline
5.29
4.90
4.46
4.26
3.10
1.73
3.5 0.1
2.12 0.07
0.77 0.04
0.44 0.02
…
27.6 0.4
12.5 0.6
6.6 0.2
…
27.4 0.4
15.4 0.2
6.1 0.2
2.3 0.2
…
3‐Methoxyaniline
3‐Aminoacetophenone
4‐Aminoacetophenone
…
0.48 0.02

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SANTOS AND GAZITÚA
nitrophenolate ion expel from T (k2). Considering this
fact, and the buffer concentration used, k3[Buffer] >> k2,
Equation 3 is obtained.
0
-1
-2
kobs ¼ ðk1 k3½BufferꢀÞ=ðk−1 þ k3½BufferꢀÞ½Anilineꢀ: (3)
If k−1 >> k3[Buffer], the kobs is simplified to Equation 4.
kobs ¼ ðk1 k3½BufferꢀÞ=ðk−1ÞÞ½Anilineꢀ
¼ K1 k3½Bufferꢀ½Anilineꢀ:
(4)
2
3
4
5
6
7
As the term k3[Buffer] is a constant independent of the
aniline used, there is no change in the slope of the
Brønsted plot.
pK + log(p/q)
a
FIGURE 2 Corrected Brønsted‐type plots for the anilinolysis of 4
), 5 ( ), and 6 (Δ)
(
On the other hand, the obtained β values, 0.55 and
0.58, for the reactions of 5 and 6, respectively, are in the
described range for concerted mechanisms (0.4‐0.7)[11]
;
with q = 2 for 4‐phenylenediamine (q = 1 for all the other
anilines) and p = 3 for all the conjugate acids of the ani-
lines.[10] These plots are linear, with slopes β = 0.87,
0.55, and 0.58 for 4, 5, and 6, respectively.
The value of β = 0.87 obtained for the anilinolysis of 4
is in accordance with those found in similar reactions
where the mechanism is stepwise and the nucleofuge is
expelled from the tetrahedral intermediate as the rate
determining step (0.8‐1.1).[1–8]
nevertheless, it is necessary to disregard the presence of
the break of the plot due to a possible stepwise mecha-
nism.[11] For the pyridinolysis of the dithiocarbonate 6,
the break must be greater than 9.5[8d]; for the anilinolysis,
the pKa° must be at a greater pKa than for the
pyridinolysis (out of the pKa studied range); consequently,
it is not possible to confirm the concerted mechanism by
using this argument.
For the anilinolysis reaction of 6, we are prone to
accept a stepwise mechanism as for substrates represented
in Scheme 1 (X═Cl) (where only 4‐nitrophenolate ion is
the nucleofuge, see above), considering (1) the SA
aminolysis reaction of 6 is stepwise (unpublished results)
and (2) the change of SA amine by aniline stabilizes a tet-
rahedral intermediate.[12] Therefore, if the mechanism is
stepwise with the SA aminolysis, it is even more justified
that it would be so for the aniline series.
Scheme 2 (X═H) shows a possible mechanism for this
reaction, considering that (1) 4‐nitrophenolate ion is the
unique nucleofuge (see Section 3.1) and (2) in the experi-
mental conditions, plots of kobs against aniline concentra-
tion are linear; therefore, the buffer is the deprotonation
agent of T .
Applying the steady‐state condition to both intermedi-
ates, Equation 2 can be obtained.
It is noticeable that although the reactions of
dithiocarbonates 4 and 6 proceed through the same mech-
anism of Scheme 2, they present different values of β. A
possible reason is that in the reactions of 6, the greater
electron withdrawing capacity of chlorobenzenethiol
would favor the reestablishment of the double bond of
the thiocarbonyl group and the expel of 4‐nitrophenolate
ion. No effect on the deprotonation step because it is dif-
fusion controlled in the reactions of both substrates.
Under these conditions, it is possible that the used
assumption k3[Buffer] >> k2 is not valid and the more
complex Equation 2 must then be used.
kobs ¼ ðk1 ðk2 þ k3½BufferꢀÞÞ=ðk−1 þ k2 þ k3½BufferꢀÞ½Anilineꢀ:
(2)
The deprotonation rate constant (k3), which is diffu-
sion controlled, is greater than that for the 4‐
If k−1 >> (k3[Buffer] + k2), Equation 2 is simplified to
Equation 5.
kobs ¼ ððk1 ðk2 þ k3½BufferꢀÞ=k−1Þ½Anilineꢀ
SCHEME 2 Proposed mechanism for the anilinolysis reactions of
dithiocarbonate 4, (X═H)
(5)
¼ K1ðk2 þ k3½BufferꢀÞ½Anilineꢀ:

SANTOS AND GAZITÚA
5 of 7
À
À
Á
kobs ¼ k1 k2 þ k′2 þ k3½Bufferꢀ =
Due to the sum in the kN expression is not possible to
use the Brønsted equation, therefore, the β values
obtained for the reaction of 6 do not have physical sense.
The HPLC study of the anilinolysis reactions of 4
shows the presence of 4‐nitrophenol and anilinium
phenyl dithiocarbamate, and in the reactions of 6,
4‐nitrophenol and 4‐chlorophenyl aniline dithiocarba-
mate were found. These results and the presence of
traces of O‐(4‐nitrophenyl) aniline thionocarbamate in
the reactions of dithiocarbonate 6 confirm that 4‐
nitrophenolate ion is the principal (or unique)
nucleofuge in these reactions. This result is in accor-
dance with the fact that, at the isobasic point, RO− is a
better nucleofuge than RS−.[8d, 13] The pKa of 4‐nitrophe-
nol is 7.5,[14] that of benzenethiol is 7.2,[8d] and that of 4‐
chlorobenzenethiol is 7.0.[8d]
(6)
À
ÁÁ
k−1 þ k2 þ k′2 þ k3½Bufferꢀ ½Anilineꢀ:
The same mechanism has been reported for the
anilinolysis of O‐(4‐cyanophenyl) O‐(3‐nitrophenyl)
thionocarbonate.[9] The presence of the 2 nucleofuges
in the anilinolysis reaction of 5 shows that the
nucleofugacity of 4‐nitrophenolate ion is similar to that
of 4‐nitrophenylbenzenethiolate from the tetrahedral
intermediate I (Scheme 4), despite the differences in
their basicities (pKa values of 4‐nitrophenol and 4‐
nitrobenzenethiol are 7.5 and 4.5, respectively).[14]
3.3 | Influence of amine nature on the
nucleofugality of groups
To propose a mechanism for the anilinolysis of 5, it is
not possible to use the same argument above‐mentioned
for 6, considering the stabilization of the tetrahedral inter-
mediate by change of the amine nature. In fact, by going
from pyridines to SA amines as nucleophiles, the reaction
mechanism of 5 changes from stepwise to concerted,[8f]
but, as is known, anilines stabilize a tetrahedral interme-
diate relative to SA amines but destabilize it relative to
pyridines.[12]
To determine the influence of the amine nature on the rela-
tive nucleofugality of groups, we compare the behavior of
the reactions of 5 with 3 amines families. In the anilinolysis,
both groups are nucleofuges from the tetrahedral intermedi-
ate I (Scheme 4); also in the reaction of 5 with SA amines,[8f]
both groups are nucleofuges; but in the last, the mechanism
is concerted (tetrahedral intermediate II could not exist).
On the other hand, it is important to mention that
in both reactions, pyridinolysis[8d] and anilinolysis (this
study), the mechanism is stepwise. Nevertheless, in the
pyridinolysis reactions, only 4‐nitrophenolate ion is
expelled from the tetrahedral intermediate III,[8d] while
in the anilinolysis, from the tetrahedral intermediate I,
Regarding the close similarity of the kN values of both
substrates (5 and 6) in Table 1, it is possible to assume that
both go by the same stepwise mechanism.
The HPLC study of the reactions of
5 with
aniline shows the presence of 4‐nitrophenol, the
dimer of 4‐nitrobenzenethiol, 4‐nitrophenyl aniline
thionocarbamate, and 4‐nitrophenyl aniline dithiocar-
bamate. This result shows that both groups attached
to thiocarbonyl group are nucleofuges. A possible
reaction mechanism is shown in Scheme 3.
Applying the steady‐state condition to both intermedi-
ates, Equation 6 can be obtained.
SCHEME
4
Zwitterionic tetrahedral intermediates in the
reactions of 5 with anilines (I), SA amines (II), and pyridines (III)
SCHEME 3 Proposed mechanism for
the anilinolysis reactions of
dithiocarbonate 5, (X═NO2)

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SANTOS AND GAZITÚA
both 4‐nitrophenolate and 4‐nitrobenzenethiolate are
nucleofuges. This result reinforces the idea that the
amine nature changes the relative nucleofugality of
groups.
occur through a stepwise mechanism with 2 tetrahedral
intermediates, one zwitterionic (T ) and the other anionic
(T−), with the borate buffer as the proton transfer agent.
The nucleofugacity of 4‐nitrophenolate ion is similar
to that of 4‐nitrobenzenethiolate from the tetrahedral
intermediate I, despite the differences in their basicities
(3 pKa units).
In the reactions of O‐(4‐nitrophenyl) S‐(4‐nitrophenyl
dithiocarbonate (5), the change of nucleophile from pyri-
dines (one nucleofuge, 4‐nitrophenolate ion) to anilines
(2 nucleofuges, 4‐nitrophenolate and benzenethiolate
ions) shows that the nature of the amine affects the
relative nucleofugality of groups.
3.4 | Influence of nonleaving group on the
nucleofugality
An important question arises from the comparison of
results for the anilinolysis of 5 (this study) with those
of the same reactions of 2 and 3 in the same experimen-
tal conditions.[8e] Although for these substrates the
mechanism is stepwise, the kinetic behavior is different.
In fact, for the reactions of 2 and 3, the plots of kobs ver-
sus aniline concentrations are curved up and those for 5
are linear. To explain the upward curve in the plots, it
was supposed that the deprotonating agents were both
the buffer anion and a second amine molecule. In all
these reactions, the aniline and buffer concentrations
are similar; therefore, the deprotonation rate constants
must be similar. In the case of 2 and 3, the rate
equation is kobs = K1(k2 + k3[A−]) N + K1k3N2 (eq. 3
in Castro et al[8e]), where N corresponds to the amine
and A− represents the anionic form of the buffer. Never-
theless, in the reaction of 5, the second term disappears
probably because k2 for the reaction of 5 is greater than
that for 2 and 3. This is probably due to the greater elec-
tron withdrawing of the 4‐nitrophenoxy group favoring
the 4‐nitrobenzenethiolate expel.
The nonleaving group is not passive and plays an
important role in the relative nucleofugality of groups
depending largely on its capability of electron
withdrawing.
ACKNOWLEDGEMENTS
This work was supported by projects ICM‐MINECON,
RC‐130006‐CILIS, and FONDECYT of Chile (project
1130044).
ORCID
José G. Santos http://orcid.org/0000-0002-5017-2164
REFERENCES
In the anilinolysis reactions of 2 and 3, only 4‐
nitrobenzenethiolate is the nucleofuge, whereas in the
reaction of 5, the 4‐nitrophenolate ion is also the
nucleofuge. This can be explained by the greater electron
withdrawing capacity of the 4‐nitrophenolate moiety
compared with 4‐chloro or 4‐methyl phenolate moieties
in the tetrahedral intermediate. In the same way, in
the anilinolysis of 4 and 6, 4‐nitrophenolate ion is the
unique nucleofuge, while in the reactions of 5, 4‐
nitrobenzenethiolate is also a leaving group. This can be
explained in part due to the different electron withdraw-
ing capabilities of the S‐(4‐nitrophenyl) group compared
with benzenethiolate group, which diminish the expul-
sion of 4‐nitrophenolate and compete as a nucleofuge.
These results strongly support the idea that the
nonleaving group is not passive and plays an important
role in the relative nucleofugality of groups.
[1] E. A. Castro, Chem. Rev. 1999, 99, 3505.
[2] E. A. Castro, M. Gazitúa, P. Ríos, P. Tobar, J. G. Santos, J. Phys.
Org. Chem. 2009, 22, 443.
[3] E. A. Castro, Pure Appl. Chem. 2009, 81, 685.
[4] H. K. Oh, J. Y. Lee, J. W. Yun, Y. S. Park, I. Lee, Int. J. Chem.
Kinet. 1998, 30, 419.
[5] H. K. Oh, J. Y. Oh, D. D. Sung, I. Lee, Coll. Czech. Chem. Comm.
2004, 69, 2174.
[6] (a) M. I. Page, A. Williams, Organic and Bio‐organic Mecha-
nisms, Longman, Harlow 1997, Chapter 7; (b) A. Williams,
Concerted Organic and Bio‐organic Mechanisms, CRC Press,
Boca Raton 2000, Chapter 4; (c) F. A. Carroll, Perspectives on
Structure and Mechanism in Organic Chemistry, Brooks/Cole
Publishing Co, Pacific Grove 1998, 434; (d) A. Williams, Adv.
Phys. Org. Chem. 1992, 27, 2.
[7] a) W. P. Jencks, Chem. Rev. 1985, 85, 511; b) M. J. Gresser, W. P.
Jencks, J. Am. Chem. Soc. 1977, 99, 6963; c) M. J. Gresser, W. P.
Jencks, J. Am. Chem. Soc. 1977, 99, 6970.
[8] a) E. A. Castro, L. Leandro, J. G. Santos, Int. J. Chem. Kinet.
1999, 31, 839; b) E. A. Castro, M. Gazitua, J. G. Santos,
J. Phys. Org. Chem. 2011, 24, 466; c) E. A. Castro, M. Gazitua,
J. G. Santos, J. Phys. Org. Chem. 2009, 22, 1003; d) E. A. Castro,
M. E. Aliaga, M. Gazitua, J. G. Santos, J. Phys. Org. Chem. 2012,
25, 994; e) E. A. Castro, M. Gazitua, J. G. Santos, J. Phys. Org.
4 | CONCLUSIONS
The reaction of O‐(4‐nitrophenyl) S‐aryl dithiocarbonates
(4‐6) with anilines has been examined. The analysis based
on the kinetic study demonstrates that these reactions

SANTOS AND GAZITÚA
7 of 7
Chem. 2010, 23, 176; f) E. A. Castro, M. E. Aliaga, M. Gazitúa, P.
Pavez, J. G. Santos, J. Phys Org, Chem 2014, 27, 265.
[14] E. A. Castro, M. Cepeda, P. Pavez, J. G. Santos, J. Phys. Org.
Chem. 2009, 22, 455.
[9] R. Montecinos, M. E. Aliaga, P. Pavez, J. G. Santos, New J.
Chem. 2017, 41, 9954.
SUPPORTING INFORMATION
Additional Supporting Information may be found online
in the supporting information tab for this article.
[10] R. P. Bell, The Proton in Chemistry, Methuen and Co. Ltd.,
London 1959, 159.
[11] a) E. Chrystiuk, A. Williams, J. Am. Chem. Soc. 1987, 109, 3040;
b) A. Williams, Acc. Chem. Res. 1989, 22, 387; c) A. Williams,
Free Energy Relationships in Organic and Bio‐Organic Chemis-
try, The Royal Society of Chemistry, Cambridge 2003 171; d)
E. A. Castro, M. Ramos, J. G. Santos, J. Org. Chem. 2009, 74, 6374.
How to cite this article: Santos JG, Gazitúa M.
The reactions of O‐(4‐nitrophenyl) S‐aryl
dithiocarbonates with anilines: Effects on the
relative nucleofugality. J Phys Org Chem. 2018;
e3818. https://doi.org/10.1002/poc.3818
[12] E. A. Castro, P. Muñoz, J. G. Santos, J. Org. Chem. 1999, 64, 8298.
[13] (a) K. T. Douglas, M. Alborz, J. Chem. Soc. Chem. Commun.
1981, 551; b) K. T. Douglas, Acc. Chem. Res. 1986, 19, 186.