Kinetics of oxidative ammonolysis of 4-bromo-o-xylene: III. Conversion of 4-bromo-o-tolunitrile as a substrate

Article abstract of DOI:10.1134/S1070363213030158

Kinetics of oxidative ammonolysis of 4-bromo-o-tolunitrile on V-Sb-Bi-Zr/γ-Al₂O₃-oxide catalyst in the temperature range 633-673 K were studied. We found that the rate of conversion of 4-bromo-o-tolunitrile to the target 4-bromphthalonitrile and CO₂ was described by the half-order equation with respect to the substrate concentration and was independent of the partial pressures of oxygen and ammonia. The byproducts are 4-bromophthalimide formed through the hydrolysis of 4-bromophthalonitrile, CO₂ produced by oxidation of 4-bromo-o-tolunitrile and decarboxylation of 4-bromophthalimide, and 4-brombenzonitrile produced from 4-bromo-o-tolunitrile and 4-bromophthalimide.

Full text of DOI:10.1134/S1070363213030158

ISSN 1070-3632, Russian Journal of General Chemistry, 2013, Vol. 83, No. 3, pp. 492–495. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © G.A. Bagirzade, 2013, published in Zhurnal Obshchei Khimii, 2013, Vol. 83, No. 3, pp. 439–442.
Kinetics of Oxidative Ammonolysis of 4-Bromo-o-xylene:
III.1 Conversion of 4-Bromo-o-tolunitrile as a Substrate
G. A. Bagirzade
Nagiev Institute of Chemical Problems, National Academy of Sciences of Azerbaijan
H. Javid ave. 29, Baku, Az1143 Azerbaijan
e-mail: iradam@rambler.ru
Received January 24, 2012
Abstract―Kinetics of oxidative ammonolysis of 4-bromo-o-tolunitrile on V–Sb–Bi–Zr/γ-Al2O3-oxide catalyst
in the temperature range 633–673 K were studied. We found that the rate of conversion of 4-bromo-o-
tolunitrile to the target 4-bromphthalonitrile and CO2 was described by the half-order equation with respect to
the substrate concentration and was independent of the partial pressures of oxygen and ammonia. The by-
products are 4-bromophthalimide formed through the hydrolysis of 4-bromophthalonitrile, CO2 produced by
oxidation of 4-bromo-o-tolunitrile and decarboxylation of 4-bromophthalimide, and 4-brombenzonitrile
produced from 4-bromo-o-tolunitrile and 4-bromophthalimide.
DOI: 10.1134/S1070363213030158
It is known [1] that the oxidative ammonolysis in
the vapor phase of 4-bromo-o-xylene on V–Sb–Bi–Zr/
γ-Al2O3-oxide catalyst results in 4-bromophthalo-
nitrile, an important product of organic synthesis. In
the study of kinetics of this reaction we have shown
previously [2, 3] that 4-bromo-o-tolunitrile is an
intermediate in the formation of the target 4-bromo-
phthalonitrile.
ammonia [p(NH3)] when the latter was somewhat
larger than a certain value, designated as [p(NH3)]min
[3], as well as the effect of contact time τ on the
process rate in the temperature range 633–673 K.
The effect of oxygen concentration on the process
of oxidative ammonolysis of 4-bromo-o-tolunitrile was
examined at the initial partial pressures p0(bromotolu-
nitrile) = 1.30 kPa, and p0(NH3) = 32.19 kPa. In the
studied range of p(O2) (2–19 kPa), the rate of total
conversion of 4-bromo-o-tolunitrile W(bromotolu-
nitrile), and the rate of formation of 4-bromophthalo-
nitrile and CO2 did not depend on the partial pressure
of oxygen at τ = 0.27 s and temperature 653 and 673 K.
It seemed appropriate to study the kinetic re-
gularities of the transformation of 4-bromo-o-tolu-
nitrile in the reaction of oxydative ammonolisys on the
specified catalyst.
Kinetic measurements of the transformation of 4-
bromo-o-tolunitrile and chromatographic separation of
the reaction product components, as well as quanti-
tative calculation of their content, were carried out in
accordance with the previously developed techniques
[2]. In the oxidative ammonolysis of 4-bromo-o-
tolunitrile on V–Sb–Bi–Zr/γ-Al2O3-oxide catalyst the
formation proceeds of 4-bromophthalonitrile, 4-
bromphthalimide, 4-brombenzonitrile, and CO2.
The study of the influence of p(NH3) at τ = 0.27 s,
p0(bromotolunitrile) = 1.30 kPa, and p0(O2) = 8.19 kPa,
at temperatures 653 and 673 K on W(bromotolunitrile)
and the rates of individual reactions showed that the
rate of overall conversion of 4-bromo-o-tolunitrile, as
well as the rate of the formation of 4-bromo-
phthalonitrile and CO2 did not depend on the con-
centration of ammonia in the range of 19–58 kPa.
To clarify the nature of the oxidative ammonolysis
of 4-bromo-o-tolunitrile reaction kinetic, we studied
the effect of partial pressures of oxygen [p(O2)] and
Tables 1, 2 show the results of experiments on the
variation of τ at p0(bromotolunitrile) = 1.52 kPa, p(O2) =
9.55 kPa, and p0(NH3) = 53.03 kPa. It is evident that
the increase in the τ results in the increase in the
degree of conversion of 4-bromo-o-tolunitrile (α) and
1
For communication II, see [1].
492

KINETICS OF OXIDATIVE AMMONOLYSIS OF 4-BROMO-o-XYLENE: III.
493
Table 1. Effect of the contact time on the selectivity of the
oxidative ammonolysis of 4-bromo-o-tolunitrile
Table 2. Effect of the contact time on the kinetics of the
oxidative ammonolysis of 4-bromo-o-tolunitrile
Si, %
Pi, kPa
Wsum
,
Wsum
,
τ, s
α, %
τ, s
α, %
mmol g–1 h–1
mmol g–1 h–1
NH3 H2O
II
III
IV
СО2
I
II
III
633 K
633 K
0.14
7.45
0.52
0.50
0.47
0.45
0.43
0.41
97.41
97.40
95.13
94.25
93.50
92.74
–
–
–
2.59
2.60
2.61
2.63
2.65
2.67
0.14 7.45
0.27 13.79
0.43 21.09
0.59 26.99
0.75 33.53
0.91 38.89
0.52
0.50
0.47
0.45
0.43
0.41
1.402 0.11
1.306 0.20
1.196 0.30
–
–
–
52.92 0.34
52.83 0.62
52.73 0.94
0.27 13.79
0.43 21.09
0.59 26.99
0.75 33.53
0.91 38.89
–
–
2.26
2.35
2.45
2.52
0.77
1.40
2.07
1.106 0.39 0.0031 52.64 1.20
1.007 0.48 0.0071 52.56 1.48
0.926 0.55 0.0122 52.48 1.71
673 K
673 K
0.14 24.31
0.27 41.71
0.43 58.29
0.59 68.43
0.75 75.70
0.91 81.72
1.71
1.50
1.31
1.13
0.98
0.87
95.70
95.69
93.24
92.70
92.21
91.74
–
–
–
4.30
4.31
4.32
4.33
4.35
4.37
0.14 24.31
0.27 41.71
0.43 58.29
0.59 68.43
0.75 75.70
0.91 81.72
1.71
1.50
1.31
1.13
0.98
0.87
1.147 0.35
0.883 0.60
0.632 0.82
–
–
–
52.68 1.10
52.43 1.88
52.21 2.59
–
–
2.44
2.50
2.58
2.64
0.47
0.86
1.25
0.478 0.96 0.0049 52.07 3.03
0.368 1.06 0.0100 51.97 3.34
0.277 1.14 0.0150 51.89 3.59
in a decrease in W(bromotolunitrile). With the increase
in τ the selectivity of conversion of 4-bromo-o-4-
tolunitrile into bromophthalonitrile diminishes, and the
selectivity of formation of 4-bromophthalimide and
4-bromobenzonitrile grows. The dependence of the
selectivity of the CO2 formation on τ is less pro-
nounced. This indicates that the CO2, in contrast to 4-
bromophthalimide and 4-bromobenzonitrile formed
mainly from 4-bromo-o-tolunitrile directly, while 4-
bromophthalimide and 4-bromobenzonitrile are formed
in a consecutive way. Also, the absence of 4-
bromophthalimide and bromobenzonitrile in the reac-
tion products at low contact time and the appearance of
4-bromo-o-tolunitrile at a relatively high degree of
transformation points to the consecutive nature of their
formation. Thus, analysis of variation of the selectivity
of the reaction products (Si) as a dependence on the α
suggests that 4-bromophthalonitrile is subjected to
secondary transformations in the oxidative ammono-
lysis of 4-bromo-o-tolunitrile under the influence of
H2O, which is the product of accompanying reactions
[4, 5] of oxidative ammonolysis, namely, the oxidative
dehydrogenation and deep oxidation of the substrate.
In accordance with the above data, 4-bromo-
phthalonitrile is apparently hydrolyzed to 4-bromo-
phthalimide, which in turn is decarboxylated to 4-
bromobenzonitrile. Also, apparently there is an
additional pathway of 4-bromobenzonitrile formation
directly from 4-bromo-o-tolunitrile through oxidative
decomposition, which is more clearly seen at increas-
ing temperature and contact time. This result is con-
sistent with the data of [3] on the study of the kinetics
of oxidative ammonolysis of 4-bromo-o-xylene, because
in this case the 4-bromo-o-tolunitrile is formed as an
intermediate [2] and is subjected to further trans-
formation.
Based on our studies, we write the reaction scheme
of the oxidative ammonolysis of 4-bromo-o-tolunitrile
as follows:
1
CH3
CH3
CH3
CH3
Br
Br
6
2
3
4
CO2
CN
5
CO
CO
NH
Br
Br
Thus, the overall kinetics of 4-bromo-o-tolunitrile
transformation is described by the equation
WI = kpIn,
(1)
where k is the apparent rate constant of the total
transformation of 4-bromo-o-tolunitrile.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 3 2013

494
BAGIRZADE
log KI
log WI
tan α 0.5
tan α = E/2.3R
log PI
Fig. 1. The dependence of log W1 on log P1 in the oxidative
ammonolysis of 4-bromo-o-tolunitrile at T = 673 K.
The experimental data in coordinates log W(bromo-
tolunitrile) = kp(bromotolunitrile) (Fig. 1) at 673 K
showed that the order of the reaction described by
Eq. (1) is equal to 0.5. Similar dependences were
observed at 633 and 653 K. Taking this into account,
the Eq. (1) can be written as
1/T×103
Fig. 2. The dependence of the logarithm of the constant of
the overall conversion of 4-bromo-o-tolunitrile on the
reciprocal temperature.
WI = kpI0.5,
(2)
The apparent activation energy for the conversion
of 4-bromo-o-tolunitrile, determined graphically from
the Arrhenius plot, was found equal to 119 kJ mol–1
The constancy of the constants at varying the
contact time evidences the fulfillment of Eq. (2).
Table 3. Dependence of the rate of accumulation of the reaction products of 4-bromo-o-tolunitrile on the contact timea
pi, kPa
τ, s
NH3
H2О
I
II
III
0.14
0.27
0.43
0.59
0.75
0.91
1.314
1.149
0.965
0.815
0.695
0.589
0.19
0.35
0.53
0.65
0.76
0.85
–
52.84
52.68
52.50
52.38
52.27
52.18
0.60
1.09
1.64
2.04
2.38
2.68
–
–
0.005
0.011
0.019
а 653 K, p0I 1.52 kPa, p0(O2) 9.55 kPa, p0(NH3) 53.03 kPa.
Table 4. Dependence of the rate of consumption of 4-bromo-o-tolunitrile on the contact timea
Wi, mmol g–1 h–1
III
experiment calculation experiment calculation experiment calculation experiment calculation experiment calculation
τ, s
СО2
I
II
IV
0.14
0.27
0.43
0.59
0.75
0.91
0.94
0.87
0.83
0.76
0.70
0.65
0.95
0.88
0.82
0.75
0.70
0.64
0.91
0.84
0.78
0.71
0.65
0.60
0.91
0.85
0.78
0.70
0.64
0.59
–
–
–
–
0.033
0.031
0.029
0.027
0.025
0.023
0.033
0.031
0.029
0.026
0.024
0.022
–
–
–
–
–
–
0.020
0.019
0.018
0.017
0.021
0.020
0.018
0.017
0.006
0.009
0.013
0.006
0.010
0.013
а 653 K, p0I 1.52 kPa, p0(O2) 9.55 kPa, p0(NH3) 53.03 kPa.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 3 2013

KINETICS OF OXIDATIVE AMMONOLYSIS OF 4-BROMO-o-XYLENE: III.
The activation energy is given in J mol–1.
495
(Fig. 2). Consequently, the numerical value of the rate
constant of conversion of 4-bromo-o-tolunitrile is
expressed as:
Tables 3, 4 show the rates of accumulation of the
reaction products and consumption of 4-bromo-o-
tolunitrile calculated using Eqs. (4)–(9) and the
constants selected for them. The deviations between
the experimental and calculated values do not exceed
the experimental accuracy. Also, from Tables 3, 4 it is
clearly seen that the regularities of dependence on τ at
653 K are similar to those at temperatures 633 and
673 K (see Tables 1, 2).
k = k0exp (119000/RT).
(3)
Given the above, the rates of the certain pathways
(see the scheme) in the region where the partial
pressure of oxygen and ammonia is above their
minimum value, can be described by the following
equations, which are consistent with the data of [3].
W1 = k1pI0.5
,
(4)
(5)
(6)
(7)
(8)
(9)
REFERENCES
W2 = k2pI,
W3 = k3[pIIp(H2O)/p(NH3)],
W4 = k4[pIII/p(H2O)],
W5 = k5,
1. Bagiradze, G.A., Zh. Obshch. Khim., 2010, vol. 80,
no. 8, p. 1360.
2. Bagiradze, G.A., Zh. Obshch. Khim., 2010, vol. 80,
no. 9, p. 1460.
W6 = k6pI0.5
.
3. Bagiradze, G.A., Abstract of Papers, II Mezhdunarod.
konf. Rossiskogo khimicheskogo ob–va im. D.I.
Mendeleeva “Innovatsionnye khimicheskie tekhnologii i
biotekhnologii materialov i produktov” (II Int. Conf.
Russian Chemocal Society of D.I. Mendeleev
“Innovative Chemical Technology and Biotechnology
of Materials and Products”), Мoscow: RKhTU im. D.I.
Mendeleeva, 2010, p. 197.
The constants in the Eqs. (4)–(9) were selected to
fulfill the condition of minimizing the sum of the
squares of relative errors between the experimental and
calculated rates of accumulation of all the reaction
products.
k1 = 109.60exp(–121117.7/RT),
k2 = 109.61exp(–143865.7/RT),
k3 = 10–9.62exp(118685.2/RT),
k4 = 10–2.87exp(38249.9/RT),
k5 = 104.72exp(–84218/RT),
k6 = 1011.44exp(–162013.4/RT).
4. Bagiradze, G.A., Sheinin, V.Е., Magerramova, Z.Yu.,
and Rizaev, R.G., Azerb. Khim. Zh., 2000, no. 1, p. 60.
5. Rizaev, R.G., Bagiradze, G.A., Sheinin, V.Е., Mager-
ramova, Z.Yu., Guswinov, I.А., and Akhmedov, М.М.,
Proc. of Sci. Conf. on 95 Years Anniversary of
Academician M.F. Nagiyev, Baku: IKhP NANA, 2003,
p. 14.
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