The influence of the structure of aliphatic amine on its catalytic activity in the oxidation of anthrone in dimethyl sulfoxide

Article abstract of DOI:10.1134/S0036024411060276

The catalytic activity of several aliphatic amines in the liquid-phase oxidation of anthrone by molecular oxygen in dimethyl sulfoxide was studied. The kinetic data obtained were compared with the results of quantum-chemical calculations. The catalytic activity of aliphatic amines in the reaction under consideration was directly proportional to an increase in the absolute value of the heat of formation of the corresponding ammonium cation.

Full text of DOI:10.1134/S0036024411060276

ISSN 0036ꢀ0244, Russian Journal of Physical Chemistry A, 2011, Vol. 85, No. 6, pp. 1094–1096. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.A. Serdyuk, M.G. Kasyanchuk, I.A. Opeida, S.V. Tolkunov, 2011, published in Zhurnal Fizicheskoi Khimii, 2011, Vol. 85, No. 6, pp. 1195–1197.
SHORT
COMMUNICATIONS
The Influence of the Structure of Aliphatic Amine on Its Catalytic
Activity in the Oxidation of Anthrone in Dimethyl Sulfoxide
A. A. Serdyuk, M. G. Kasyanchuk, I. A. Opeida, and S. V. Tolkunov
Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, Donetsk, Ukraine
eꢀmail: ann.serdyuk@rambler.ru
Received July 13, 2010
Abstract—The catalytic activity of several aliphatic amines in the liquidꢀphase oxidation of anthrone by
molecular oxygen in dimethyl sulfoxide was studied. The kinetic data obtained were compared with the
results of quantumꢀchemical calculations. The catalytic activity of aliphatic amines in the reaction under
consideration was directly proportional to an increase in the absolute value of the heat of formation of the
corresponding ammonium cation.
Keywords: catalytic activity, anthrone oxidation, aliphatic amine structure.
DOI: 10.1134/S0036024411060276
INTRODUCTION
the addition of amines under the specified conditions,
equally as amines without anthrone. In presence of
ammonia or aliphatic amines, the reaction has a high
rate. The kinetic curves have the form of curves with
saturation; that is, in certain time, that absorption of
oxygen by the solution stops. Such curve shape is
explained by the complete consumption of the subꢀ
strate undergoing oxidation.
Amines of various nature exhibit catalytic activity
in several reactions, in particular, they catalyze the liqꢀ
uidꢀphase oxidation of aromatic ketones by molecular
oxygen in aprotic solvents [1]. Interrelation between
the structure and activity of amines was considered in
[
2–4], where the influence of the structure was related
to such factors as the influence of substituents (the
induction and steric effects and the effect of conjugaꢀ
tion), the solvation of amines and their protonated
forms, and the influence of the geometry of electronic
orbitals (the hybrid state responsible for the properties
of the lone pair of electrons on nitrogen).
The purpose of this work was to study the catalytic
activity of amines depending on their structure and
determine the amine electronic structure characterisꢀ
tics that allow their catalytic activity to be predicted.
The object of study was the reaction of anthrone oxiꢀ
dation by molecular oxygen in dimethyl sulfoxide
The kinetic curves are described by the firstꢀorder
kinetic equation
[O ] = [O ] (1 – exp(–k t)),
2 t 2 ∞ eff
with a correlation coefficient of 0.99. Here, [O2]t is the
equilibrium concentration of oxygen absorbed at the
given time moment, mol/l; [O2]∞ is the equilibrium
concentration of oxygen that would be absorbed if the
reaction continued infinitely long, mol/l; keff is the
–1
effective rate constant, s ; and t is time, s.
Proton NMR studies were performed on a
BRUKER Avance II instrument (400 MHz). It was
found [1] that anthrone transformed into
anthraquinone when it was oxidized almost comꢀ
pletely (only traces of the side product of the reaction,
bianthrone, were present [5]).
(
[
DMSO). The kinetics of this reaction was studied in
1]. We used aliphatic amines with different chain
lengths (3ꢀmethylbutylamine, butylamine, ethyꢀ
lamine, 2ꢀmethylpropylamine, ꢀbutylamine, dodecyꢀ
t
lamine, diethylamine, triethylamine, and trimethyꢀ
lamine) as catalysts.
RESULTS AND DISCUSSION
EXPERIMENTAL
The effective constants (keff) and other kinetic
parameters are listed in Table 1. The ratio between the
The kinetics of the reaction was monitored by volꢀ
umetric measurements of oxygen absorption, the number of moles of oxygen ( ) absorbed by the end
N
O2
reaction was performed under kinetic conditions. of the reaction and the number of moles of the subꢀ
Constant oxygen pressure (760 torr) and temperature strate introduced into the reaction was stoichiometric
(
307 K) were maintained in experiments. The initial (1 : 1). Typical kinetic curves of the absorption of oxyꢀ
concentration of anthrone was 0.05 mol/l in all experꢀ gen in the catalytic oxidation of anthrone are shown in
iments. Anthrone is not oxidized in DMSO without Fig. 1.
1094

THE INFLUENCE OF THE STRUCTURE
1095
Table 1. Stoichiometry of the oxidation of anthrone (
c
= 0.05 mol/l) in DMSO at 760 torr and 307 K in the presence of
ethylamine (ce is the concentration of ethylamine)
2
2
–1
5
ce
×
10 , mol/l
[O ] ± 0.001 mol/l
∞
2
(
kef
±
0.06)
×
10 , s
W0
×
10 , mol/(l s)
NS/N
O2
0
0
0
0
0
.17
.26
.5
0.05
0.04
0.05
0.05
0.05
0.10
5.1
5.3
0.98
1.13
0.12
0.21
0.24
0.38
10.5
11.3
17.5
1.01
.6
1.05
.77
1.08
Mean 1.05
± 0.05
Table 2. Electronic structure characteristics and the rates of reactions catalyzed by amines
Substance
–logW0
–ΔH, kcal/mol –ЕHOMO, eV
ЕLUMO, eV
–ЕHOMO(ion), eV ЕLUMO(ion), eV
Dodecylamine
3.96
3.94
3.98
4.04
4.09
4.12
4.42
4.5
117.74
9.67
9.88
9.90
9.77
9.90
10.04
9.64
9.32
9.61
2.92
2.95
3.03
3.03
2.95
2.93
2.62
2.42
2.55
11.30
11.80
12.49
12.15
11.67
13.03
12.59
12.11
13.74
1.34
1.32
1.38
1.27
1.31
0.92
0.34
–0.02
0.31
3
ꢀMethylbutylamine
Ethylamine
ꢀMethylpropylamine
Butylamine
ꢀButylamine
117.83
118.22
118.12
117.79
115.25
103.20
98.06
2
t
Diethylamine
Triethylamine
Trimethylamine
4.71
95.83
Note: Calculations were performed using MOPACꢀ2009(COSMO, in a medium with permittivity 48.9); the kinetic data on the last four comꢀ
pounds were taken from [8].
Important parameters characterizing the reactivity
of amine molecules are the energies of the highest
(r = 0.98) (Fig. 2) and with ЕLUMO (r = 0.91) of the
molecule of the corresponding unprotonated amine in
a medium with permittivity equal to that of DMSO.
Compared with heat effects and frontier orbital enerꢀ
gies calculated in a medium with permittivity 48.9,
heat effects and frontier orbital energies calculated in
occupied (ЕHOMO) and lowest unoccupied (ЕLUMO
)
molecular orbitals. According to Fukui, the properties
of frontier orbitals can to a considerable extent deterꢀ
mine the character of chemical transformations of a
molecule [6]. It was, in particular, shown that the рКа
values of solutions of certain aliphatic amines in glaꢀ
cial acetic acid changed linearly as the energy of the
highest occupied molecular orbital changed, but in the
opposite direction [7].
c
(O ), mol/l
2
5
4
3
2
1
The results of quantumꢀchemical calculations of
0
.04
the heat effects of protonation of amines ( H) and the
Δ
properties of amine frontier orbitals (ЕHOMO and
ЕLUMO) and the frontier orbitals of their cations
(
ЕHOMO(ion) and ЕLUMO(ion)) and the kinetic data
0
.02
0
obtained are listed in Table 2. The method for
semiempirical calculations of molecules was selected
by comparing the results obtained using several
semiempirical methods (PM3, PM6, and AM1) with
the experimental data [8]. The correlation coefficient
for the PM3 method was 0.98, which allowed the heats
of formation of amine molecules to be estimated with
accuracy within ±1.86 kcal/mol.
400
800
t
, s
Fig. 1. Kinetic curves of oxygen absorption in the oxidaꢀ
tion of anthrone ( = 0.05 mol/l) in DMSO at 760 torr and
07 K in the presence of ethylamine; ( ) 0.0017,
) 0.0026, ( ) 0.005, ( ) 0.006, and ( ) 0.0077 mol/l.
c
For logW0, the best correlation is observed with
3
1
the heat effect of protonated amine formation (
Δ
H
)
(
2
3
4
5
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A
Vol. 85
No. 6 2011

1096
SERDYUK et al.
ACKNOWLEDGMENTS
−
Δ
H, kcal/mol
110
100
90
The authors thank N.G. Korzhenevskaya and
A.A. Matveev of the Institute of Physical Organic and
Coal Chemistry, National Academy of Sciences of
Ukraine, for consultations.
4
.2
.6
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r
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7
higher
amine.
Δ
H in magnitude, the more active is the
8
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A
Vol. 85
No. 6 2011