Communication-electrosynthesis of isonicotinic acid via indirect electrochemical reduction of pyridine in the presence of CO2

Article abstract of DOI:10.1149/2.1121603jes

The electrocatalytic reduction of CO₂ by Schiff base of N, N'-bis(3-hydroxy-2-naphthaldehyde)-1,3-phenylenediimino (NMPD) was studied in an acetonitrile solvent and at room temperature. Indirect electrocatalytic activity of NMPD for reduction of pyridine was empirically demonstrated. It is rational, to view electrocatalytically activated CO₂, CO₂^·-, with a dual activity toward pyridine. The spectral characteristics of the coulometric product indicated that isonicotinic acid is the final product of pyridine reduction in the presence of NMPD and CO₂.

Full text of DOI:10.1149/2.1121603jes

H240
Journal of The Electrochemical Society, 163 (3) H240-H242 (2016)
0
013-4651/2016/163(3)/H240/3/$33.00 © The Electrochemical Society
Communication—Electrosynthesis of Isonicotinic Acid via Indirect
Electrochemical Reduction of Pyridine in the Presence of CO
Kobra Ghobadi, Hamid R. Zare, Hossein Khoshro, and Alireza Gorji
2
z
Department of Chemistry, Yazd University, Yazd 89195-741, Iran
ꢀ
The electrocatalytic reduction of CO2 by Schiff base of N, N -bis(3-hydroxy-2-naphthaldehyde)-1,3-phenylenediimino (NMPD) was
studied in an acetonitrile solvent and at room temperature. Indirect electrocatalytic activity of NMPD for reduction of pyridine was
•−
empirically demonstrated. It is rational, to view electrocatalytically activated CO2, CO2 , with a dual activity toward pyridine. The
spectral characteristics of the coulometric product indicated that isonicotinic acid is the final product of pyridine reduction in the
presence of NMPD and CO2.
©
2016 The Electrochemical Society. [DOI: 10.1149/2.1121603jes] All rights reserved.
Manuscript submitted November 20, 2015; revised manuscript received December 29, 2015. Published January 8, 2016.
Using CO
considerable attention. In spite of CO
nontoxic, and inexpensive resource, the large overpotential required
for CO conversion leads to a low efficiency of recycling this molecule
2
in the synthesis of organic compounds has received
2
being as the most abundant,
2
1
into useful products. Hence, finding catalysts to decrease this high
overpotential and to increase the selectivity of reduction processes has
become an important concern. For this purpose, a number of transi-
N
N
2
tion metal complexes and some organic compounds, like substituted
3
4
benzenes and benzil, have been used.
This paper focuses on the electrocatalytic reduction of CO
by Schiff base of N, N -bis(3-hydroxy-2-naphthaldehyde)-1,3-
phenylenediimino (NMPD). Isonicotinic acid was synthesized as the
2
ꢀ
OH
HO
ꢀ
N,N -bis(3-hydroxy-2-
Scheme 1. Structure
of
Schiff
base
of
product of indirect reduction of pyridine in the presence of CO
2
and
naphthaldehyde)-1,3-phenylenediimino, NMPD.
NMPD electrocatalyst. Also, it was shown that the reduction product
of CO
2
has a dual activity for the synthesis of isonicotinic acid by
ꢀ
ꢀ
an EC C CC mechanism. As reported in the literature, isonicotinic
acid has been used as a photosensitive resin stabilizer, an electro-
plating additive and an anticorrosion reagent. Also, this compound
Electrolysis procedure.—CPC was used in 40.0 mL acetonitrile
containing 0.1 mM TBAP and 0.1 mmol NMPD as a catalyst in the
presence of 1.0 mmol of pyridine. Prior to every experiment, the solu-
5
2
tion was bubbled with Ar gas for 20 minutes. CO was continuously
6
bubbled into the solution during the electrolysis and a constant po-
tential of −2.0 V was applied to the working electrode. The results
showed that pyridine conversions were about 100% after passing 2.9
−1
F mol of the starting compound (pyridine) at room temperature. The
determined yield of isonicotinic acid was about 75%. At the end of
the electrolysis, the solvent was completely removed, and the residue
was dissolved in diethyl ether and filtered (5 × 20 mL). After separa-
1
tion of the isonicotinic acid product, it was characterized by FTIR, H
13
and C NMR. The spectral characteristics of isonicotinic acid were
1
3
obtained as follow: H NMR (CDCl , 400 MHz): δ 7.43 (d.d, 2H, j
1
13
=
3.2), δ 7.62 (d.d, 2H, j = 3.2), δ 11.03 (s, H, CO
2
H); C NMR
(
CDCl , 100.6 MHz): δ 128.09, 130.95, 132.39, 167.79 ppm; FTIR:
3
1714 (C=O), 1095, 1217 (C-O), 3380 (O-H).
2
used as a solvent. CO and Ar had a purity of 99.995%.
Cyclic voltammetry was performed using an EG&G PARSTAT
273 equipped with a Power Suite software in a conventional three-
Results and Discussion
2
Electrosynthesis of isonicotinic acid by indirect electrocatalytic
electrode electrochemical cell containing a glassy carbon electrode
reduction of pyridine in the presence of CO
2
.—Voltammograms (a),
+
(
(
GCE) with a diameter of 2 mm as the working electrode, Ag/Ag
0.01 M AgNO
(
b) and (c) of Fig. 1 are the cyclic voltammograms of the working elec-
trode in an acetonitrile solution containing 0.1 M TBAP and 1.0 mM
pyridine (voltammogram a), 1.0 mM NMPD (voltammogram b) and
3
in a 0.1 M tetrabutylammonium perchlorate (TBAP),
acetonitrile solution) as the reference electrode, and a Pt wire as the
counter electrode. Controlled potential coulometry (CPC) was carried
out using a SAMA 500 electroanalyzer system in an undivided glass
cell equipped with a gas inlet and outlet with a graphite rod as the
1
.0 mM pyridine + 1.0 mM NMPD (voltammogram c). The experi-
mental results indicate that the cyclic voltammograms of the saturated
solution of CO and also 1.0 mM pyridine solution which is saturated
with CO are exactly same as voltammogram (a). Consequently, solu-
tions containing pyridine alone, saturated solution of CO , or 1.0 mM
pyridine which is saturated with CO are inactive electrochemically
2
2
+
cathode, a platinum plate (ca. 5 cm ) as the anode, and Ag/Ag (0.01
M AgNO in 0.1 M TBAP acetonitrile solution) as the reference
electrode. Fourier transform infrared (FTIR) spectrum analysis was
2
3
2
2
1
13
performed on an EQUINOX55 spectrometer. H and C NMR were
measured on a DRX-400 (Bruker) spectrometer with CDCl as a
solvent in the presence of SiMe as an internal standard. All the
in the potential range of −1.0 to −2.6 V, pyridine cannot be reduced
3
by NMPD, and also NMPD only consists of one cathodic peak at
4
the potential of −2.03 V that is related to the reduction of imine
measurements were performed at room temperature.
bond and the formation of its radical anion as shown in reaction 1.9
Voltammogram (d) corresponding to 1.0 mM NMPD solution in the
presence of CO . The current response of voltammogram (d) indicates
2
zE-mail: hrzare@yazd.ac.ir
Downloaded on 2016-01-12 to IP 144.122.201.150 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Journal of The Electrochemical Society, 163 (3) H240-H242 (2016)
H241
2
10
22
34
80
2
1
1
1
1
1
.00
.80
.60
.40
.20
.00
a
y = 0.738x + 1.3781
R² = 0.9955
b
y = 0.5436x + 1.1998
R² = 0.9885
c
60
-
-
-
y = 0.4687x + 0.992
R² = 0.9828
d
y = 0.4413x + 0.7987
R² = 0.9859
4
2
0
0
0
0.80
0.30
e
f
0.50
0.70
0.90
t1/2
5
1
g
-2.7
-2.1
-1.5
-0.9
E vs. (Ag / Ag+ (0.01 M)) / V
0
5
10
t / s
15
20
Figure 1. Cyclic voltammograms of a glassy carbon electrode in an acetoni-
trile solution containing 0.1 M TBAP and (a) 1.0 mM pyridine, (b) 1.0 mM
NMPD, (c) 1.0 mM pyridine + 1.0 mM NMPD, (d) 1.0 mM NMPD in the
presence of CO2. (e), (f) and (g) as (d) in the presence of 1.0, 2.0 and 3.0 mM
Figure 2. Chronoamperograms of a glassy carbon electrode in an acetonitrile
solution containing 0.05 M TBAP, 1.0 mM NMPD and (a) saturated with CO2,
(
b), (c), (d) and (e) as (a) in the presence of 0.2, 0.3, 0.5, 0.7 mM pyridine,
1
/2
−1
respectively. Inset shows plots of I /IL vs. t obtained from chronoampero-
pyridine respectively. Potential scan rate: 100 mV s
.
C
grams 1–5.
that the reduction peak current of the NMPD increases dramatically
in the presence of CO . Also, a comparison voltammograms of (a)
and (d) indicates the overpotential decrease of CO reduction in the
presence of NMPD is more than 500 mV. These results are indicative
form of the Galus equation.13 The calculations indicate the average
−1 −1
2
value of k is 244.4 ± 50.5 M
S .
2
In order to confirm the final product of pyridine reduction in the
•−
presence of CO
2
and NMPD, controlled potential coulometry, CPC,
•−
of electrocatalytic reduction of CO
2
to CO
2
, regeneration of NMPD
was performed at −2.0 V as described in the Experimental section.
and, finally, its participation in the electrocatalytic cycle according to
Then, the coulometric product was separated and characterized by
10
reactions 1 and 2.
1
13
FTIR, H and C NMR spectroscopy. The spectral characteristics of
the coulometric product (not shown) indicate that isonicotinic acid is a
NMPD + e → NMPD•− (E)
[1]
final product of pyridine reduction in the presence of CO
2
and NMPD.
In other words, the spectral characteristics of the coulometry product
•
−
•−
ꢀ
•−
•−
NMPD + CO
2
→ NMPD + CO
2
(C )
[2]
indicate that Py is coupled with CO and, thus, the final product
2
2
−
of coulometry is dianion of isonicotinic acid, PyCOO, as shown
in reactions 4. It is noted, the coulometry experiment was performed
Also, the voltammetric results show a significant rise in the electro-
catalytic cathodic peak current with an increase of CO concentration
in the solution. This result is further proof for the electrocatalytic
activity of NMPD in reduction of CO . Voltammograms (e), (f) and
g) of Fig. 1 are the cyclic voltammograms of acetonitrile (0.1 mM
TBAP) solutions containing 1.0 mM NMPD, CO and different con-
2
under CO
2 2
atmosphere and in the absence of O . After electrolysis, the
solution was exposed under air. As a result, the product of isonicotinic
2
2
−
acid is obtained from the oxidation of PyCOO by dissolved O
2
in
(
the analyte solution according to reaction 5.
2
•
−
•−
→ PyCOO2− (C)
centrations of 1.0, 2.0 and 3.0 mM of pyridine, respectively. The
dependence of the cathodic peak current on the concentration of pyri-
dine proves that CO serves as an electron transfer mediator, or a
catalyst, for pyridine reduction (reaction 3). In other words, elec-
Py + CO
2
[4]
•
−
2
−
−
2e
2
11
PyCOO → PyCOOH (C)
[5]
•−
tron transfer from CO
radical anions of pyridine, Py , as shown in reaction 3.
parison of the gradual increase of the electrocatalytic current of the
CO reduction by NMPD in the presence of pyridine (voltammograms
2
to the aromatic ring leads to production of
Therefore, the reaction of pyridine with CO
NMPD follows an EC C CC mechanism (reactions 1–5), and the final
product is isonicotinic acid. This mechanism and the final product is
same as those reported in our previous work. However, more sol-
ubility and also, easier synthesis of the mediator, NMPD, respect to
the other catalysts such as the Ni(II) complex are advantages for this
work. In addition, CPC results indicate that diminution of the current
during the electrolysis, in the presence of NMPD is significantly less
than that observed for the Ni(II) complex. This observation demon-
strates more stability of NMPD respect to the Ni(II) complex as an
2
in the presence of
•−
11,12
ꢀ
ꢀ
A com-
11
2
e-g) with the electrochemical reduction of NMPD in the presence of
pyridine (voltammogram c) as well as the electrocatalytic reduction
in the presence of NMPD (voltammogram d) indicates that
pyridine is indirectly reduced by electrocatalytically activated CO
the presence of NMPD, as shown in reaction 3.
11
of CO
2
2
in
•−
→ Py•− + CO
ꢀ
Py + CO
2
2
(C )
[3]
2
electron transfer mediator for reduction of CO .
Chronoamperometry was employed to evaluate the electron trans-
fer catalytic rate constant, k, for the reaction between pyridine and
Conclusions
•−
1/2
CO
tration of pyridine is shown in Fig. 2, inset. I
of pyridine in the presence of CO and NMPD and I
2
(Fig. 2). The variation of I
C
/I
L
versus t for different concen-
is the catalytic current
is the limited
C
In the present study, we have provided evidence for electrocat-
alytic reduction of CO by Schiff base of N,N-bis(3-hydroxy-2-
2
L
2
current in the absence of pyridine. The value k of the catalytic process
can be obtained from the slope of these plots according to the reduced
naphthaldehyde)-m-phenylenediamine, NMPD, as an excellent elec-
trocatalyst. The voltammetric results indicate that the reduction
Downloaded on 2016-01-12 to IP 144.122.201.150 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

H242
Journal of The Electrochemical Society, 163 (3) H240-H242 (2016)
•
−
product of CO
2
, CO
2
, in the presence of NMPD serves as a mediator
5. G. D. Yadav, S. S. Joshi, and P. S. Lathi, Enzyme Microb. Technol., 36, 217 (2005).
1
13
6. A. Gennaro, C. M. S a´ nchez-S a´ nchez, A. A. Isse, and V. Montiel, Electrochem. Com-
mun., 6, 627 (2004).
to reduce pyridine. The spectral characteristics of FTIR, H and
NMR of the coulometry product have proved that isonicotinic acid is
the final product of indirect electrocatalytic reduction of pyridine in
C
. A. Malandra, M. Cantarella, O. Kaplan, V. Vejvoda, B. Uhn a´ kov a´ , B. Stepankova,
ˇ ˇ ´
´
7
D. Kub a´ cˇ , and L. Mart ´ı nkov a´ , Appl. Microbiol. Biotechnol., 85, 277 (2009).
the presence of NMPD and CO
2
.
8. M. I. Ayad and M. M. Ayad, J. Mater. Sci. Mater. Electron., 4, 125 (1993).
. V. Titov, V. Bondarenko, V. Koshechko, and V. Pokhodenko, Theor. Exp. Chem., 44,
71 (2008).
9
2
References
10. A. J. Bard and L. R. Faulkner, Electrochemical Methods: Fundamentals and Appli-
cations, Wiley, New York, 2001.
1
2
3
. E. Lamy, L. Nadjo, and J. M. Saveant, J. Electroanal. Chem., 78, 403 (1977).
. T. Sakakura, J. C. Choi, and H. Yasuda, Chem. Rev., 107, 2365 (2007).
. J. A. Rosso, S. G. Bertolotti, A. M. Braun, D. O. Martire, and M. C. Gonzalez, J.
Phys. Org. Chem., 14, 300 (2001).
11. H. Khoshro, H. R. Zare, A. A. Jafari, and A. Gorji, Electrochem. Commun., 51, 69
(2015).
12. V. Koshechko and V. Pokhodenko, Theor. Exp. Chem., 33, 230 (1997).
13. Z. Galus, Fundamentals of Electrochemical Analysis, Ellis Horwood Press, New
York, 1994.
4. V. Koshechko and V. Lopushanskaya, Theor. Exp. Chem., 42, 33 (2006).
Downloaded on 2016-01-12 to IP 144.122.201.150 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).