Reduction of 4-nitrosodiphenylamine with sodium hydroxy- and aminoalkanesulfinates

Article abstract of DOI:10.1023/B:RJAC.0000018684.42943.eb

The kinetics of reduction of 4-nitrosodiphenylamine with sodium alkanesulfinates were studied, and the reaction mechanism was suggested.

Full text of DOI:10.1023/B:RJAC.0000018684.42943.eb

Russian Journal of Applied Chemistry, Vol. 76, No. 11, 2003, pp. 1787 1791. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 11,
2003, pp. 1837 1841.
Original Russian Text Copyright
2003 by Polenov, Egorova, Ryazantseva.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Reduction of 4-Nitrosodiphenylamine with Sodium Hydroxy-
and Aminoalkanesulfinates
Yu. V. Polenov, E. V. Egorova, and S. G. Ryazantseva
Ivanovo State Chemical Engineering University, Ivanovo, Russia
Received March 13, 2003
Abstract The kinetics of reduction of 4-nitrosodiphenylamine with sodium alkanesulfinates were studied,
and the reaction mechanism was suggested.
Reduction of 4-nitrosodiphenylamine (NDPA) to
4-aminodiphenylamine (ADPA) is of great practical
importance, since ADPA is an intermediate product in
preparation of antioxidants. In particular, condensation
of ADPA with acetone yields 4-isopropylaminodi-
phenylamine (commercial name Diafen FP) [1], which
is thermal stabilizer for polyethylene, polystyrene, and
synthetic rubber, inhibitor of tarring of motor fuel,
and stabilizer of leaded gasolines. In recent years,
derivatives of alkanesulfinic acids containing various
substituents at the first carbon atom were found to be
highly promising in reduction of organic nitro and
nitroso compounds. The feature of these compounds is
the presence of abnormally long C S bond, which
Sodium hydroxymethanesulfinate (SHMS), sodium
hydroxyethanesulfinate (SHES), and sodium amino-
methanesulfinate (SAMS) used as reducing agents
were prepared by the procedures described in [5, 6].
The concentrations of their solutions were determined
by iodometric titration [7].
NDPA was reduced directly in the colorimeter cell,
which was placed into a temperature-controlled jacket
connected to a UT-2 thermostat (the temperature was
maintained with the accuracy of 0.5 C). The reaction
rate was determined by measuring the optical density
of the NDPA solution at = 400 nm, which corre-
sponds to the absorption maximum in its electronic
spectrum. It was found preliminarily that the reaction
products and the reducing agent do not absorb light at
this wavelength. The optical density was measured
on a KFK-2 spectrophotometer equipped with an
Shch-1516 digital dc voltmeter.
under certain conditions ruptures to form active inter-
2
mediates having high reducing power: SO
and
2
2
S O ions and SO radical anions [2]. The use of
2
4
2
sodium hydroxymethylsulfinate as a reducing agent
allows preparation of ADPA from NDPA in almost
quantitative yield [3]. The mechanism of this reaction
was thoroughly studied. It was shown that the initial
substance can be reduced both with sulfoxylate anions
and directly with hydroxymethanesulfinate molecules
[4]. The absence of side reactions allows reliable
determination of the rate constants of the stages in-
volving decomposition of the reducing agent and the
reaction of sulfoxylate anions with the oxidant. These
parameters can be used for optimizing processes in-
volving such reducing agents.
All kinetic measurements were carried out at more
than thousand-fold excess of the reducing agent,
which provides practically constant concentration of
the reducing agent in the course of the experiment.
Preliminary experiments showed that the reaction
of NDPA with SHMS in aqueous alkaline solution
yields a compound that can be isolated by distillation
in a vacuum at approximately 200 C. The melting
point of this compound is 66 67 C, the half-wave
reduction potential on a dropping mercury electrode
E
=
0.23 V (anodic wave), and the appearance
In this connection, it is appropriate to study the
possibility of NDPA reduction with derivatives of
alkanesulfinic acids with the aim to compare their
reactivity and performance and also to elucidate the
process mechanism.
1/2
of the product corresponds to published data for
ADPA [8, 9].
To determine the stoichiometry of the reaction
between SHMS and NDPA, we mixed the solutions of
these compounds in 1 M aqueous NaOH. The result-
ing mixture was kept under argon at 73 C until de-
colorization, after which the SHMS content was deter-
mined iodometrically.
EXPERIMENTAL
NDPA was prepared by threefold recrystallization
of the commercial product from ethanol.
1070-4272/03/7611-1787$25.00 2003 MAIK Nauka/Interperiodica

1788
POLENOV et al.
Table 1. Determination of the stoichiometric ratio of the
reactants in reduction of NDPA with SHMS. Initial amount
of NDPA 0.0147 mol
duction of 2-nitro-2 -hydroxy-5 -methylazobenzene
(NAB) [10], the reaction between alkanesulfinates and
NDPA proceeds without an induction period, with
the reaction order with respect to the oxidant being
fractional.
ADPA
obtained
*
**
Yield of
ADPA,
%
SHMS
SHMS
NDPA: SHMS*
It is well known that reactions involving SHMS are
inhibited by formaldehyde. This is due to the fact
that the reducing species in some cases are not the
molecules of the reducing agent but the products of
their decomposition, sulfoxylate ions, formed by the
reversible reaction [1]
mole
0.7178 0.0138
0.1078 0.0145
0.1051 0.0145
0.0799
0.0769
0.0742
1 : 1.9
1 : 2.1
1 : 2.1
94
99
99
* Before reaction.
** After reaction.
HOCH2SO2
HSO2 + CH2O.
(2)
Table 1 shows that, under these conditions, ADPA
is formed in quantitative yield, with the ratio of the
reacted NDPA and SHMS being 1 : 2. Qualitative
analysis showed that, in the course of reduction, sul-
fite sulfur is formed.
Addition of formaldehyde and acetaldehyde in-
hibits the reaction in question (Fig. 1, curves 1 and 3),
and at sufficiently high concentrations of the additives
the reaction order with respect to NDPA becomes
equal to 1 (Fig. 2a).
These results suggest the stoichiometric reaction
equation
However, attempts to completely inhibit the reac-
tion by adding aldehydes, as in the case of NAB and
indigocarmine, failed [10, 11]. For example, in reduc-
tion of SHMS, the reaction rate on adding formalde-
hyde decreases by 60% at maximum, and with further
addition of formaldehyde it remains constant. For
SAMS, according to the equation of its decomposition
with rupture of the C S bond, aminomethanol should
be an additive shifting the equilibrium to formation of
nondissociated reducing agent molecules:
NONa + 2HOCH2SO2 Na + 2H2 O
N
+
+ 2HOCH SO Na NaOH.
NH2
NH
(ADPA)
SHMS and SAMS are analogs of sodium hydroxy-
=
2
3
(1)
methanesulfinate [1]. Hence, there is good reason to
believe that the reduction of NDPA with SHES and
SAMS proceeds by a stoichiometric equation similar
to Eq. (1).
NH2CH2SO2 + OH
SO2 + NH2CH2OH.
(3)
The kinetic curves of NDPA reduction with various
reducing agents are shown in Fig. 1. Contrary to re-
Aminomethanol does not exist in the free state
[12]; therefore, it is impossible to carry out experi-
ments with its addition to SAMS.
cNDPA 105, M
For all the reducing agents studied, the reaction
rate varies in direct proportion to the concentration of
the reducing agent (Fig. 2b) both in the presence of
aldehydes and without them.
The above experimental data suggest that reduction
of NDPA with derivatives of alkanesulfinic acids
proceeds by two parallel pathways: direct reaction of
NDPA with molecules of reducing agent (associative
pathway) and reaction with the products of decom-
position of reducing agent molecules, sulfoxylate
anions (dissociative pathway). Based on the above and
also published data [13], which note that the nitroso
group is reduced in steps, we can propose the follow-
ing reaction pattern (for SHMS as an example):
, min
Fig. 1. Kinetic curves of NDPA reduction. (c
) NDPA
NDPA
concentration; ( ) time. (1, 2) SHMS, 309 K, c = 0.5519,
red
c
= 0.37 M; (3, 4) SHES, 303 K, c = 0.071, c
=
OH
red
= 0.414, c
OH
0.6 M; (5) SAMS, 313 K, c
= 1.02 M.
red
OH
(2, 4, 5) In the absence of additives; addition of the corre-
sponding aldehyde, M: (1) 0.21 and (3) 0.02.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 11 2003

REDUCTION OF 4-NITROSODIPHENYLAMINE
1789
Associative pathway
lncNDPA [M]
(a)
HOCH 2SO2 + H2O
+
N
NO
I
SO23
k
as
+
CH2O
+
,
NHOH
NH
II
(4)
(5)
II + HOCH2SO2
ADPA + HOCH2SO23 .
Dissociative pathway
, min
1
vov 107, mol l 1 min
k
(b)
1
HOCH2SO2 + OH
SO22 + CH2(OH)2,1
(6)
k
1
k
I + HSO2 + 2H2O2
II + SO23 ,
(7)
(8)
II + HSO2 + 2H2O
ADPA + HSO23 .
Since in the presence of aldehyde the reaction order
with respect to the reducing agent and NDPA is equal
to 1, we can assume that, in the associative pathway,
reaction (4) will be the limiting stage and the sub-
sequent fast stage (5) will not affect the overall rate of
the process. The first reaction order with respect to the
reducing agent in the absence of aldehyde additions
and the inhibiting effect of the aldehydes suggest, by
analogy with reduction of NAB, that in reduction by
the dissociative pathway the limiting stage is cleavage
of the reducing agent molecules (6). Applying the
steady-state concentration method to stages (6) and
(7), and considering the associative pathway, we
obtain the kinetic equation
cr, M
on duration of NDPA
Fig. 2. Dependences of (a) lnc
NDPA
reduction and (b) the reaction rate v on concentrations
ov
of the reducing agents c : (a) (1) SHMS, 309 K, c
=
r
r
0.5519, c
0.0634, c
0.4088, c
= 0.37, c = 0.21 M; (2) SHES, 303 K, c =
OH
OH
OH
a
r
= 0.17, c = 0.013 M; (3) SAMS, 303 K, c =
a
r
= 0.86 M. (b) (1) SHES, 283 K, c
= 0.5,
OH
5
5
c
c
= 2.5 10 , c = 5 10 M; (2) SAMS, 303 K,
NDPA
OH
a
5
= 0.75, c
= 2 10 ; (3) SHMS, 308 K, c
= 2.5 10 , c = 0.21 M.
=
NDPA
OH
5
0.37, c
NDPA
a
For this purpose, based on the results of experi-
ments performed at aldehyde concentrations sufficient
to suppress pathways (6) (8), we found k values
as
dcNDPA
dt
k1 k2 cNDPA crcOH
(Table 2). Then, from the difference between the
vov
=
= vdis + vas
+ kas cNDPA cr,
where v , v , and v are the overall reaction rate
=
overall rate v and the rate by the associative path-
way v , we evaluated the reaction rates by the dis-
sociative pathway v , entering into the linear form
ov
k c + k2 cNDPA
1 a
as
(9)
dis
of the kinetic equation
1
Bca
ov dis
as
= A +
,
(10)
and the reaction rates by dissociative and associative
vdis
cNDPA
1
1
pathways, respectively (mol l s ); c
and c are concentrations of NDPA, hydroxide ions,
, c
, c ,
NDPA OH r
Table 2. Kinetic parameters of NDPA reduction with
a
sodium alkanesulfinates
reducing agent, and aldehyde (or aminomethanol),
respectively (M); k and k are the rate constants of
1
1
T = 283 K
kas k1
T = 293 K
kas k1
1
1
stage (6) (l mol s ); k and k are the rate constants
Reduc-
ing
agent
2
as
1
1
of stages (7) and (4), respectively (l mol s ).
Equation (6) can be experimentally verified for
the reducing agents studied by analogy with reduction
of NAB with SHMS [10].
l mol 1 s
1
4
3
5
9
3
3
4
9
6
8
SHMS 9.5 10
SHES 1.13 10
SAMS 6.7 10
1.13 10
2.2 10
6.7 10
1.3 10
5.5 10
3.17 10
2.5 10
3.5 10
1.43 10
7
9
1
Methylene glycol is hydrated form of formaldehyde in alkali
solution.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 11 2003

1790
POLENOV et al.
Table 3. Kinetic parameters of NDPA reduction with
4
(1/vdis
)
10 , l mol 1 min
SAMS
(a)
vov = f (cOH
)
vov = f (cNDPA)
T, K
kas 103 k1 108
kas 103
k1 108
1
l mol 1 s
303
308
313
1.5 0.3 2.3 0.6
2.6 0.3 4.0 1.0
6.0 1.0 6.0 1.0
1.1 0.2
2.5 0.5
4.0 0.8
4.0 1.0
4.0 1.0
6.0 2.0
4
1
ca 103, M; (1/cNDPA
)
10 , l mol
4
(1/vdis
)
10 , l mol 1 min
Table 4. Angular coefficients of dependences vov = f (cr)
for NDPA reduction with SAMS
(b)
Angular coefficient
T, K
evaluation by Eq. (1)
experimental
6
6
303
308
313
3.02 10
6.14 10
7.01 10
2.88 10
5.2 10
7.86 10
6
6
6
6
4
1
ca 102, M; (1/cNDPA
)
10 , l mol
From the initial ordinates of the above linear
dependences, equal to the parameter A in Eq. (10), we
Fig. 3. Reciprocal reaction rate by dissociative pathway
1/v as a function of (1) concentration of aldehydes c and
dis
a
: (a) SHES,
5
evaluated the rate constants k (Table 2).
1
(2) reciprocal concentration of NDPA 1/c
NDPA
283 K; c = 0.1064, c
= 1.8; (1) c = 2.5 10
,
=
As mentioned above, it is impossible to study how
aminomethanol inhibits NDPA reduction with SAMS
by shifting the equilibrium of decomposition of
SAMS molecules by reaction (3). However, the ex-
perimental data obtained suggest that two-pathway
scheme of reduction is realized in the case of this
reducing agent also and it is possible to determine the
same kinetic parameters that as in the case of SHMS
and SHES.
r
OH
NDPA
3
(2) c 3.6 10 M; (b) SHMS, 308 K; c = 0.5519, c
a
r
OH
5
2
0.37; (1) c
= 6 10 , (2) c = 3.6 10
M.
NDPA
a
1
vov 106, mol l 1 min
The dependences of the rate of NDPA reduction
with SAMS on the concentrations of NaOH and
NDPA are shown in Fig. 4. The observed linear
dependences with positive initial coordinates are in
good agreement with the kinetic model proposed. As-
cNDPA 105, cNaOH, M
Fig. 4. Rate of NDPA reduction with HAMS v as a func-
suming that k c << k c
, Eq. (9) is simplified:
1 a
2 NDPA
ov
vov = k1crcOH + kas cNDPAcr.
(11)
tion of (1) NDPA concentration c
and (2) concen-
NDPA
tration of hydroxide ions c
at 303 K. c (1) 0.468 and
OH
r
5
The equation adequately describes the experimental
data presented in Figs. 2 and 4.
(2) 0.409; (1) c
= 0.75; (2) c
= 2 10 M.
NDPA
OH
where A = 1/(k c c
), B = k /(k k c c
).
1 r OH
1
1 2 r OH
The rate constants and activation energies were
evaluated by least-squares treatment of these depen-
dences for various concentrations of the reducing
agent and sodium hydroxide and various temperatures
(Table 3). Using the rate constants listed in Table 3,
The linearity of the plots in the coordinates 1/v
dis
c at c
and c
= const and 1/v 1/c
at
a
NDPA
OH
dis
NDPA
c and c
= const (Fig. 3) confirms the validity
a
OH
of Eq. (10).
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 11 2003

REDUCTION OF 4-NITROSODIPHENYLAMINE
1791
we evaluated the angular coefficient of the depen-
Containing Reducing Agents), Moscow: Khimiya,
1994.
dence v = f(c ) by Eq. (11) and compared with the
ov
r
experimental data (Fig. 2b) (Table 4). Satisfactory
agreement of these results additionally confirms the
adequacy of the proposed kinetic model. From the
temperature dependences of the rate constants listed in
Table 3, we evaluated the activation energies for the
associative and dissociative pathways to be 106 10
2. Makarov, S.V., Reactivity of Sulfur- and Oxygen-
Containing Reducing Agents with C S Bond, Doctor-
al Dissertation, Ivanovo, 2000.
3. USSR Inventor’s Certificate no. 1158561.
4. Polenov, Yu.V. and Budanov, V.V., Izv. Vyssh.
Uchebn. Zaved., Khim. Khim. Tekhnol., 1988, vol. 31,
no. 4, pp. 40 43.
1
and 53 2 kJ mol , respectively.
5. Makarov, S.V., Budanov, V.V., and Shalimova, G.V.,
Zh. Prikl. Khim., 1985, vol. 58, no. 5, pp. 1098 1102.
6. Makarov, S.V., Sokolova, I.N., and Budanov, V.V.,
It should be noted in conclusion that the found rate
constants k (Table 2) characterize the ease of the
1
rupture of the C S bond in alkanesulfinate molecule.
From the above data, the reducing agents can be
ranked in the following order with respect to stability:
SHES < SAMS < SHMS.
Zh. Obshch. Khim., 1985, vol. 55, no. 4, pp. 724 730.
7. Budanov, V.V., Khimiya i tekhnologiya vosstanovite-
lei na osnove sul’foksilovoi kisloty (rongalit i ego
analogi) [Chemistry and Technology of Reducing
Agents Based on Sulfoxylic Acid (Rongalite and Its
Analogs)], Moscow: Khimiya, 1984.
CONCLUSION
8. Sputnik khimika (A Guide for Chemist), Blokh, M.A.,
Based on the kinetic data for reduction of 4-nitro-
sodiphenylamine with sodium hydroxymethanesulfi-
nate, sodium hydroxyethanesulfinate, and sodium
aminomethanesulfinate, the kinetic equations were
obtained. These equations suggest that the reaction
proceeds by two parallel pathways: direct reaction of
the substrate with reducing agent molecule (associa-
tive pathway) and reaction with the product of reduc-
ing agent decomposition, sulfoxylate anion (dissocia-
tive pathway).
Ed., Leningrad: ONTIKhimteor, 1935.
9. Sarsenbaeva, G.L., Avrutskaya, I.A., and Fio-
shin, M.D., Elektrokhimiya, 1977, vol. 13, no. 2,
pp. 290 293.
10. Sokolova, I.N., Budanov, V.V., Polenov, Yu.V., and
Polyakova, I.R., Izv. Vyssh. Uchebn. Zaved., Khim.
Khim. Tekhnol., 1983, vol. 26, no. 7, p. 822.
11. Budanov, V.V., Sokolova, I.N., Solov’eva, L.B., and
Mel’nikova, B.N., Izv. Vyssh. Uchebn. Zaved., Khim.
Khim. Tekhnol., 1974, vol. 17, no. 7, pp. 993 997.
12. Nesmeyanov, A.N. and Nesmeyanov, N.A., Nachala
organicheskoi khimii (Principles of Organic Chemis-
try), Moscow: Khimiya, 1974, vol. 1.
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RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 11 2003