Influence of the structure of the macroheterocyclic ligand on the catalytic properties of metal tetraarenoporphyrazine complexes: III. Oxidative decarboxylation of oxalic acid

Article abstract of DOI:10.1007/s11176-005-0098-0

The catalytic activity of cobalt complexes of a series of tetraarenoporphyrazines in oxidative decarboxylation of oxalic acid under heterogeneous conditions was studied. The structure of the macroheterocycle exerts a significant effect on the catalytic properties of the metal complexes. 2004 MAIK "Nauka/Interperiodica".

Full text of DOI:10.1007/s11176-005-0098-0

Russian Journal of General Chemistry, Vol. 74, No. 11, 2004, pp. 1766 1769. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004,
pp. 1898 1901.
Original Russian Text Copyright
2004 by Korzhenevskii, Shikova, Koifman, Bykova.
Influence of the Structure of the Macroheterocyclic Ligand
on the Catalytic Properties
of Metal Tetraarenoporphyrazine Complexes:
1
III. Oxidative Decarboxylation of Oxalic Acid
A. B. Korzhenevskii, T. G. Shikova, O. I. Koifman, and V. V. Bykova
Ivanovo State University of Chemical Engineering, Ivanovo, Russia
Ivanovo State University, Ivanovo, Russia
Received March 13, 2003
Abstract The catalytic activity of cobalt complexes of a series of tetraarenoporphyrazines in oxidative
decarboxylation of oxalic acid under heterogeneous conditions was studied. The structure of the macrohetero-
cycle exerts a significant effect on the catalytic properties of the metal complexes.
Metal phthalocyanines catalyze oxidation of vari-
X
Y
ous organic substances, in particular, of carboxylic
acids. Their activity in oxidation of formic acid [2 6]
and in decarboxylation of pyruvic and oxalic acids
N
Y
X
X
Y
N
N
[
7, 8] was studied previously. It was found that oxalic
acid in the presence of iron phthalocyanine decom-
poses at a rate exceeding by a factor of 7 the rate of
decarboxylation of pyruvic acid under the same condi-
tions. Therefore, oxidative decarboxylation of oxalic
acid was suggested as a test reaction in evaluation of
the catalytic properties of phthalocyanines [7]:
Co
N
N
N
N
N
Y
X
Y
Ia Ic
HOOC COOH + 1/2O2
H O + 2CO .
2 2
To reveal how the structure of the macrocyclic
ligand affects the catalytic properties of the cobalt
complexes in oxidative decarboxylation of oxalic acid,
we studied the catalytic activity of the cobalt com-
plexes of tetra-2,3-pyridinoporphyrazine (2,3-PycCo,
Ib), tetrapyrazinoporphyrazine (PzcCo, Ic), 2,3-naph-
thalocyanine (2,3-NcCo, IIa), tetra-2,3-quinolinopor-
phyrazine (2,3-QlcCo, IIb), and tetra-2,3-quinoxalino-
porphyrazine (2,3-QxcCo, IIc), in comparison with
that of cobalt phthalocyanine (PcCo, Ia).
X
N
Y
X
X
N
N
N
N
Y
Co
N
N
N
Y
X
It was found previously [9] that the mechanisms of
catalytic oxidation of cysteine and oxidative decarbox-
ylation of oxalic acid in the presence of metal phthalo-
cyanines are similar, and, under the conditions of a
heterogeneous catalytic reaction, the first step is for-
mation of a catalyst substrate complex. Hence, ad-
IIa IIc
I, II, X = Y = CH (a), N (c); X = CH, Y = N (b).
sorption of oxygen is preceded by extra coordination
of oxalic acid with the metal ion, and oxidation of
oxalic acid occurs in the ternary adsorption complex.
Extra coordination of anions with the central metal
atom of phthalocyanine complexes is well known
1
For communication II, see [1].
1
070-3632/04/7411-1766 2004 MAIK Nauka/Interperiodica

INFLUENCE OF THE STRUCTURE OF THE MACROHETEROCYCLIC LIGAND... : III.
1767
2
1
0
5
4
1
1
3
2
1
1
3
2
2
3
1
0
5
1
1
4
4
5
6
7
8
0
ln Ccat
10
20
30
40
min
,
Fig. 1. Kinetic curves of catalytic oxidative decarboxyla-
tion of oxalic acid at 513 K in the presence of cobalt
4
tetraazaporphyrazines: (1) [PcCo] 20.31 10
M,
Fig. 2. Plot of lnk
tion of oxalic acid at 313 K in the presence of (1) 2,3-
NcCo, (2) PcCo, (3) 2,3-PycCo, and (4) PzcCo.
vs. lnC in oxidative decarboxyla-
app cat
4
(
2) [2,3-PycCo] 22.68 10 M, (3) [2,3-NcCo] 6.02
4
4
10
M, and (4) [PzcCo] 19.08 10 M.
[
10]. Furthermore, preliminary extra coordination of
to the substrate in the presence of all the tested metal
complexes (Fig. 1), which is consistent with published
data [8]. From the kinetic dependences obtained, we
calculated the apparent rate constants (kapp) and esti-
electron-donor molecules on the cobalt and iron ions
in the corresponding metal porphyrins facilitates the
subsequent complexation of the extra complexes with
oxygen [11].
mated the reaction order with respect to the conven-
tional molar concentration of the catalyst (Ccat)
Borisenkova et al. [8] found that the rate of decar-
boxylation of oxalic acid in the presence of metal
phthalocyanines is directly proportional to the amount
of the catalyst and is independent of the concentration
of the reacting acid within the range from 0.7 to
(
Fig. 2); in all the cases, it was unity.
Comparison of the reaction orders with respect to
the substrate and catalyst in the presence of PcCo and
the other metal complexes studied suggests that the
reaction mechanism is similar with all the cobalt tetra-
arenoporphyrazines.
1
.6 M. Based on the general concepts of chemical
kinetics, the equation for the reaction rate will be as
follows:
The constants k found from k , C , and C
ox
v
app
cat
m
n
p
m
assuming that the reaction order with respect to oxy-
gen is unity (by analogy with the reaction mechanism
in the presence of MPc [8]) can be used for comparing
the catalytic activity of the compounds and for calcu-
lating the activation energy and entropy of the reac-
tion.
dC /d = k C C
C
or dC /d = kappC ,
oa
v
oa cat ox oa oa
where Coa is the oxalic acid concentration; C , con-
ventional molar concentration of the catalyst; Cox,
oxygen concentration; k and kapp, true and apparent
rate constants; m, n, and p, reaction orders with re-
cat
v
spect to the corresponding components.
Our experimental data and calculation results char-
acterizing the kinetics of the process studied are given
in the table. These data show that the catalytic activity
of the metal complexes in oxidative decarboxylation
of oxalic acid decreases in the order 2,3-NcCo >
PcCo > 2,3-PycCo > PzcCo. The cobalt complexes of
tetra-2,3-quinolinoporphyrazine and tetra-2,3-quinox-
alinoporphyrazine appeared to be inactive in this
reaction.
It was found by the Whinkler method that the oxy-
gen concentration in the reaction zone was constant
in the course of the experiment, 1.05 10 M, which
was provided by approximately constant composition
and pressure of the gas mixture and efficient transfer
of oxygen from the gas phase to water.
3
The results of the previous studies of this test reac-
tion allowed us to choose the optimal reaction condi-
tions: aqueous solution, oxalic acid concentration
The activation parameters for all the cobalt tetra-
arenoporphyrazines studied demonstrate a compensa-
tion effect (Fig. 3), confirming that the reaction mech-
anism is similar irrespective of the structure of the
macroheterocycle. Hence, the mechanism suggested
0
1
.8 M, 40 60 C, catalyst concentration range 1
4
3
0
5
10 M.
We found that the rection is zero-order with respect
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1768
KORZHENEVSKII et al.
Catalytic activity of cobalt complexes of phthalocyanine
and its structural analogs in oxidative decarboxylation of
oxalic acid
for oxidative decarboxylation of oxalic acid catalyzed
with PcCo can be applied to the processes occurring
in the presence of the other cobalt complexes studied.
a
As in catalytic decomposition of hydrogen perox-
ide [12] and oxidation of cysteine [1], the structure of
the macroheterocyclic ligand appreciably affects the
catalytic properties of the metal complexes. In particu-
lar, aza substitution at the molecular periphery de-
creases the rate of the catalyzed reaction, and benzan-
nelation exerts a differentiating effect on the catalytic
activity, enhancing that of the phthalocyanine and
suppressing that of its aza analogs.
Ccat 104,
kapp 106,
k ,
v
T, K
1
1
l s 1 mol 1
M
mol l
s
PcCO
3
13
23
33
9.81
4.23 0.04
7.05 0.04
8.74 0.04
5.88 0.04
9.29 0.04
11.61 0.03
9.00 0.04
13.28 0.05
16.73 0.07
4.11
4.09
4.10
7.90
7.95
1
2
6.37
0.31
7.09
1.12
3.92
5.78
3
3
1
1
It was found previously that introduction of elec-
tron-withdrawing substituents into the phthalocyanine
molecule also decreases the catalytic activity of its
metal complexes [13]. In this study we observed a
similar trend.
7.94
14.84
14.74
14.79
8
.58
1
0.77
2
,3-PycCo
Apparently, the catalytic activity of metal tetra-
arenoporphyrazine complexes in oxidative decarbox-
ylation of oxalic acid, determined, in particular, by
their capability for extra coordination of the anion, is
very sensitive to variation of the electron density on
the metal atom, caused by introduction of substituents
into the macrocyclic ligand.
3
3
3
13
23
33
13.82
4.30 0.03
7.09 0.03
10.30 0.03
4.39 0.01
7.53 0.03
12.10 0.04
5.37 0.04
8.66 0.04
14.32 0.04
2.96
2.96
2.97
5.94
5.98
2
3
2.68
3.02
7.04
1.99
9.29
4.43
1
1
5.97
11.55
11.57
11.54
The remote periphery exerts a strikingly strong
effect on the catalytic activity of metal complexes of
tetraarenoporphyrazines in decarboxylation: benzanne-
lation of the secondary conjugation contours enhances
the activity of cobalt phthalocyanine but fully deacti-
vates cobalt tetra- and octaazaphthalocyanines. It is
even more surprising that benzannelation differently
affects similar reactions of catalytic (in the presence
of cobalt tetraarenoporphyrazines) oxidation of oxalic
acid and cysteine. In the latter case, the catalytic activ-
ity of the complexes increases upon benzannelation,
7
.13
1
1.82
PzcCo
313
323
333
19.08
2.59 0.03
4.52 0.02
8.05 0.04
4.92 0.04
7.51 0.03
10.05 0.03
5.17 0.04
8.54 0.03
13.03 0.03
,3-NcCo
1.29
1.29
1.29
2.75
2.75
2.75
5.59
5.57
5.57
3
5
3.25
9.15
17.01
2
3
5.99
4.80
8.81
4.59
2.28
1
2
8
0
1
2
313
323
333
3.89
3.88 0.04
5.10 0.03
6.01 0.05
4.29 0.04
6.23 0.03
8.88 0.03
4.99 0.03
7.26 0.04
10.40 0.03
9.50
9.54
9.50
17.07
16.96
16.97
30.63
30.51
30.60
70
5
6
.05
.02
2
6
5
0
0
2.39
3
3
4
.49
.99
4
1.55
2
3
.27
.24
5
0
60
E , kJ mol 1
a
1
1
1
PcCo: E 55 kJ mol
,
S
64 J K mol ; 2,3-PycCo: E
1
1
1
1
5
9 kJ mol
,
S
56 J K mol ; PzcCo: E 63 kJ mol
48 J K mol ; 2,3-NcCo: E 51 kJ mol
3 J K mol . The error in calculating E and S is 10%.
,
Fig. 3. Compensation effect in oxidative decarboxylation
of oxalic acid in the presence of (1) 2,3-NcCo, (2) PcCo,
(3) 2,3-PycCo, and (4) PzcCo.
1
1
1
S
,
S
1
1
7
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INFLUENCE OF THE STRUCTURE OF THE MACROHETEROCYCLIC LIGAND... : III.
1769
irrespective of aza substitution on the ligand periphery
1]. This dualism is hardly attributable to the purely
5. Hanke, W., Z. Anorg. Allg. Chem., 1966, vol. 347,
[
nos. 1 2, p. 67.
electronic effects of benzannelation. Most probably,
the electronic and geometric factors act in opposite
directions and exert competing effects on the catalytic
activity.
6
7
. Tanako, S., Onishi, T., and Tamari, K., Bull. Chem.
Soc. Jpn., 1968, vol. 41, no. 11, p. 2557.
. Borisenkova, S.A., Il’ina, L.M., and Rudenko, A.P.,
Vestn. Mosk. Gos. Univ., Ser. 2: Khim., 1972, vol. 13,
no. 2, p. 249.
EXPERIMENTAL
8
9
. Borisenkova, S.A., Il’ina, L.M., Leonova, E.V., and
Rudenko, A.P., Zh. Org. Khim., 1973, vol. 9, no. 9,
p. 1827.
The catalytic properties of metal complexes were
studied by published procedure [8] using a tempera-
ture-controlled rocker. The substrate conversion was
. Borisenkova, S.A., Denisova, E.P., and Danilova, T.A.,
Vestn. Mosk. Gos. Univ., Available from VINITI,
no. 1802-79.
monitored by the volume of CO evolved. The experi-
2
ments were performed at 313 333 K.
The metal complexes of tetraarenoporphyrazines
were prepared and purified according to [14 16] and
identified on the basis of spectral characteristics [14
1
0. Lever, A.B.P., Adv. Inorg. Chem. Radiochem., 1965,
vol. 7, p. 27.
1
6]. Before use, the catalyst samples were treated with
11. Bayer, E. and Schretzmann, P., Struct. Bonding, 1967,
water until the wash waters became neutral and free
of sulfates, dried to constant weight at 423 K, and
thoroughly ground.
vol. 2, pp. 181 250.
1
1
2. Korzhenevskii, A.B., Shikova, T.G., Bykova, V.V.,
and Koifman, O.I., Zh. Obshch. Khim., 2002, vol. 72,
no. 7, p. 1202.
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