Mechanistic study of electrochemical oxidation of 2,5-diethoxy-4-morpholinoaniline in aqueous solutions: hydrolysis, trimerization, and hydroxylation processes

Article abstract of DOI:10.1007/s00706-015-1409-8

Abstract The electrochemical oxidation of 2,5-diethoxy-4-morpholinoaniline has been studied in various pHs using cyclic voltammetry and controlled potential coulometry. The results indicate that the electrochemically generated p-quinonediimine participate

Full text of DOI:10.1007/s00706-015-1409-8

Monatsh Chem
DOI 10.1007/s00706-015-1409-8
ORIGINAL PAPER
Mechanistic study of electrochemical oxidation of 2,5-diethoxy-4-
morpholinoaniline in aqueous solutions: hydrolysis, trimerization,
and hydroxylation processes
Hadi Beiginejad Davood Nematollahi
•
Received: 7 May 2014 / Accepted: 2 January 2015
Ó Springer-Verlag Wien 2015
Abstract The electrochemical oxidation of 2,5-diethoxy-
4
Graphical abstract
-morpholinoaniline has been studied in various pHs using
NH
3
EtO
cyclic voltammetry and controlled potential coulometry.
The results indicate that the electrochemically generated p-
quinonediimine participates in different types of reactions
NH
2
OEt
OEt
NH
O
O
EtO
-2H
+
-2e-
N
EtO
N
O
O
O
-H+
-2e-
NH
2
EtO
O
OEt
OEt
pH=1-3
EtO
HN
NH
pH=5.3-9
NH
EtO
OEt
OEt
EtO
N
O
EtO
O
OEt
OEt
node
O
(
hydrolysis, hydroxylation, and trimerization). Instability
N
O
N
O
NH
N
A
EtO
arbon
EtO
pH=4-5.2
pH=10-13
C
OEt
O
OEt
NH
of the produced p-quinonediimine depends on its structure,
higher nucleophilicity of 2,5-diethoxy-4-morpholinoani-
line, and pH of solution. In lower pH range, rate of
hydrolysis is faster than hydroxylation and dimerization. In
intermediate pHs rate of the dimerization is faster than
hydrolysis and hydroxylation, and in the strongly alkaline
solution, rate of the hydroxylation is faster than hydrolysis
and dimerization. The effect of the charge of reaction site
N
O
EtO
HN
NH
2
-2H
-2e
+
OEt
HO
EtO
OEt
NH
EtO
OEt
-
O
NH
2
OEt
OEt
N
O
N
O
N
EtO
O
EtO
NH
O
Keywords Cyclic voltammetry Á Para-quinonediimine Á
Hydroxylation Á Density functional theory
(
C ) and N =C bond order (Wiberg bond indices) on the
1 1 1
Introduction
hydrolysis rate were studied. Calculations were performed
using density functional theory B3LYP level of theory and
Electrochemistry provides very versatile means for the
electrosynthesis and mechanistic studies [1–6]. Using
electrochemical methods with a wide time window (sub-
microseconds to hours) thermodynamic and kinetic
information about the reactions of organic and inorganic
species were obtained [7–12]. It is known that cyclic vol-
tammetry is a powerful technique for investigation of
electrochemical reactions that are coupled with chemical
reactions [13, 14]. Electrochemical studies of amines were
performed at various conditions such as aqueous and
nonaqueous solvent or at various pHs [15–21]. Electro-
chemical oxidation mechanism of aromatic amines is quite
complex, and leads to a variety of products depending on
their structure and electrolysis conditions [22, 23]. Inves-
tigations indicated that dimerization, trimerization,
hydrolysis, and hydroxylation can occur in electrochemical
oxidation of amines which is highly dependent on pH of
solution [24, 25]. Along with our previous works in
6
-311?G(p,d) basis set.
H. Beiginejad (&)
Faculty of Science, Department of Chemistry, Malayer
University, 65174 Malayer, Iran
e-mail: beiginejad.hadi@yahoo.com;
h.beiginejad@malayeru.ac.ir
D. Nematollahi
Faculty of Chemistry, Bu-Ali-Sina University, 65174 Hamedan,
Iran
123

H. Beiginejad, D. Nematollahi
electrochemical study of amines [23–28], diversity of
behavior in the electrochemical oxidation of 2,5-diethoxy-
ratio (IpC1/IpA1) is about one that can be considered as a
?
criterion for the stability of p-quinonediimine 1ox pro-
duced at the surface of electrode.
4
-morpholinoaniline (2,5-DEMA, 1) at various conditions
and also the importance of Schiff base reaction [29]
prompted us to studying electrochemical oxidation of 2,5-
DEMA at various conditions using cyclic voltammetry
More data were obtained by changing the concentration
and scan rate. Obtained CVs show that the peak current
ratio (IpC1/IpA1) decreases and C0 peak appears at less
positive potentials upon increasing the concentration of
(
CV) and controlled-potential coulometry. The results
?
show that in all pHs electrochemically generated p-qui-
2,5-DEMA (1H ) or decreasing potential scan rate. Fig-
?
ure 2 exhibits the effect of concentration of 1H on the
?
normalized CVs of 1H in water/acetonitrile (50/50)
?
2?
nonediimine (1ox or 1oxH ) is unstable and participates
in different types of reactions based on solution’s pH.
Produced p-quinonediimine hydrolyzed in lower pH range,
trimerized in intermediate pHs, and hydroxylated in strong
alkaline solution. To investigate the hydrolysis reaction
rate of electrochemically generated p-quinonediimines
solution containing 0.2 M acetate buffer (pH 4.3). Nor-
malized CVs are obtained by dividing the current by the
concentration (I/c). As it is shown in Fig. 2, the peak
current ratio (IpC1/I ) is dependent on the concentration
pA1
?
of 2,5-DEMA (1H ). Increasing substrate concentration
?
2?
(
1ox or 1Hox ), the effect of positive charge of reaction
site (C ) and bond order of C =N bonds were studied and
causes the peak current ratio (IpC1/IpA1) to decrease pro-
portionally. Using previous works on the electrochemical
oxidation of 2,5-DEMA [26, 27] and the present data, it can
1
1
1
discussed. Calculations were performed using B3LYP level
of theory and 6-311?G(p,d) basis set. Also the Wiberg
bond indices (WBI) of C =N bond and charge of reaction
be said that the cathodic peak C is related to the electro-
0
1
1
site were analyzed with the natural bond orbital (NBO)
method at mentioned level of theory.
chemical reduction of the product which is produced after
trimerization reaction.
?
Recorded CV for 1.0 mM of 2,5-DEMA (1H ) in water/
acetonitrile (50/50) solution containing 0.1 M perchloric
acid (pH 1.0) is shown in Fig. 3. The voltammogram
Results and discussion
indicates one anodic peak A at 0.44 V and two cathodic
1
Electrochemical behavior in pH 1–9
peaks C and C at 0.39 and 0.26 V vs. Ag/AgCl, respec-
1
2
tively. C and A are counterpart and correspond to the
1
1
2
?
transformation of 1H to p-quinonediimine (1Hox ) and
2?
The cyclic voltammogram (CV) recorded for 1.0 mM of
2
2
,5-diethoxy-4-morpholinoaniline (2,5-DEMA) in water/
vice versa within a two-electron, two-proton process. The
acetonitrile (50/50) solution containing 0.2 M acetate
buffer (pH 4.3) is shown in Fig. 1. The CV exhibits one
anodic peak (A ) at 0.30 V and a cathodic peak (C ) at
current of the cathodic peak C depends on the potential
1
scan rate and increases with increasing it. This result
1
1
0
.20 V vs. Ag/AgCl, respectively which corresponds to the
?
transformation of 2,5-DEMA (1H ) to p-quinonediimine
?
1ox ) and vice versa within a quasi-reversible two-elec-
tron process [26]. Under this condition, the peak current
(
Fig. 2 Normalized CVs of 2,5-DEMA in water/acetonitrile (50/50)
solution containing 0.2 M acetate buffer (pH 4.3) at various
concentrations.
a 1.0 mM, b 2.0 mM, and c 5.0 mM. Scan
-1
rate = 50 mV s , t = 25 ± 1 °C. Inset cyclic voltammograms of
a the first and b the second cycle of 1.0 mM 2,5-DEMA (1H ) in
?
Fig. 1 CV 1.0 mM of 2,5-DEMA in water/acetonitrile (50/50)
solution containing 0.2 M acetate buffer (pH 4.3); scan rate:
water/acetonitrile (50/50) solution containing 0.2 M acetate buffer
-1
(pH 4.3), scan rate 25 mV s , t = 25 ± 1 °C
-1
5
0 mV s , t = 25 ± 1 °C
1
23

Mechanistic study of electrochemical oxidation
1
NH
1
NH2
EtO
1
EtO
1
OEt
OEt
N
O
N
O
1Hox2+
ox+
1
Charge on C = +0.168
Charge on C = +0.307
1
1
WBI of C =N : 1.80
WBI of C =N : 1.47
1
1
1
1
1 1 1
Fig. 4 Calculated charge on the reaction sites (C ) and WBIs N =C
bonds, using B3LYP level of theory and 6 - 311G ? (p,d) basis set
Fig. 3 CVs 1.0 mM of 2,5-DEMA in water/acetonitrile (50/50)
solution containing 0.1 M perchloric acid (pH 1.0); scan rate:
-1
5
0 mV s , t = 25 ± 1 °C
2
?
indicates that 1Hox in the timescale of our experiments
is unstable and participates in following chemical reac-
tions. Previous works show that in this condition the
hydrolysis is a chemical following reaction and the
cathodic peak C relates to the electrochemical reduction of
2
the product which is produced after hydrolysis reaction [26,
2
7].
Comparing Figs. 1 and 3 shows that instability of the
produced p-quinonediimine increases upon decreasing pH.
It was reported that based on structures of species, rate of
hydrolysis for some amines increases with increasing pH,
while it decreased for some others [28]. To explain the
observed difference in the electrochemical oxidation
behavior in lower pH range and intermediate pHs, com-
putational study was used. In more acidic pHs (pH 1–3),
there is a direct relation between acidity and instability of
Fig. 5 CV 1.0 mM of 2,5-DEMA in water/acetonitrile (50/50)
solution containing 0.2 M phosphate buffer (pH 7.0); scan rate:
2
?
-1
p-quinonediimine (1oxH ). Our reported results show that
the N=C bond order (WBI) and charge on the reaction site
50 mV s , t = 25 ± 1 °C. Inset: variation of peak current ratio (IC1
/
I
A1) vs. scan rate
(
[
C ) have significant roles in the hydrolysis reaction rate
1
2
?
28]. Increasing the positive charge on C atom and con-
1
nucleophilicity of 2,5-DEMA (1H
acidic solution due to protonation of 1 which causes
2
) decreases in more
sequently increasing its electrophilicity makes it more
susceptible to nucleophilic attack by hydroxide ion or
water which causes increasing hydrolysis reaction rate.
?
decreasing rate of dimerization, protonation of 1ox and
2
?
formation of 1oxH in this condition cause increasing
instability of produced p-quinonediimine [26, 28]. In other
words, using this data it could be concluded that in the
intermediate pHs rate of the dimerization is faster than
hydrolysis, and in the lower pH range the rate of the
hydrolysis is faster than dimerization.
Also =NR is a leaving group and the hydrolysis rate is
2
inversely proportional to the strength of N=C bonds, in
which the lower the WBI of N=C bond, the higher the rate
of the hydrolysis reaction [28]. The positive charge on the
?
reaction sites (C ) and WBIs of C =N bonds for 1ox and
1
1
1
2
oxH were calculated using density functional theory
?
1
CV of 2,5-DEMA (1) in water/acetonitrile (50/50)
-
2-
(
DFT) and natural bond orbital (NBO) analysis (Fig. 4). As
solution containing 0.2 M buffer H
is shown in Fig. 5. As shown in this figure the CV exhibits
one anodic peak A at 0.19 V and two cathodic peaks C
and C at 0.155 and -0.02 V vs. Ag/AgCl, respectively.
The anodic and cathodic peaks A and C are counterpart
2
PO
4
/HPO
4
(pH 7.0)
2
can be seen not only charge on C in 1oxH is more
?
1
?
positive than charge on C in 1ox but also WBI of C =N
2
bond in 1oxH is lower than that of 1ox . According to
1
1
1
1
1
?
?
0
these results, it could be concluded that although higher
1
1
123

H. Beiginejad, D. Nematollahi
3
reported in the published paper [26], 80 cm buffer H PO /
and correspond to the transformation of 1 to the p-qui-
?
nonediimine 1ox and vice versa within a quasi-reversible
3
4
-
H PO (0.2 M, pH 2.0) containing 0.05 mmol of 1 was
2 4
two-electron, one-proton process [26]. As can be seen the
peak current ratio (IpC1/IpA1) is less than one and increases
upon increasing the scan rate (inset of Fig. 5). This result
subjected to electrolysis at 0.40 V vs. Ag/AgCl in a divided
cell. The electrolysis was terminated when the current
decayed to 5 % of its original value and 1a was extracted
by ethylacetate. Figure 7, curve b shows obtained cyclic
voltammogram 0.5 mM of 1a in aqueous solution con-
taining 0.01 M sodium hydroxide. By comparing CVs of
1a and 1 under the same condition the idea of hydrolysis
reaction as a chemical following reaction is rejected.
Based on what was reported in the literature, dimeriza-
tion as a following chemical reaction can be recognized by
the use of changing the concentration of studied species, in
which dilution solution of 2,5-DEMA (1) and consequently
decreasing the rate of dimerization causes increasing the
peak current ratio (IpC1/IpA1) [26]. To study effect of con-
centration, normalized cyclic voltammograms of 1 at
various concentrations in pH 12 were obtained. Normalized
CVs are obtained by dividing the current by the concen-
tration (I/c). Figure 8 shows that the peak current ratio
(IpC1/IpA1) is independent of concentration of 2,5-DEMA
(1). These data reject the dimerization reaction after the
electron transfer process as the first following chemical
reaction.
?
indicates that 1ox in the timescale of our experiments is
unstable and participates in following chemical reactions.
The new cathodic peak C is related to the electrochemical
0
reduction of the product which is produced after trimer-
ization [26]. Comparing CVs 1.0 mM of 2,5-DEMA in pH
4
.3 and 7 shows although there are same following
chemical reaction after electrochemical oxidation of 2,5-
DEMA, but the peak current ratio (IpC1/IpA1) in pH 4.3 is
more than that of pH 7.0 which is shown that rate of the
following chemical reaction in pH 4.3 is lower than that of
pH 7.0. Electrochemical oxidation of 2,5-DEMA (1) at
various pHs shows that the electrode surface reaction at
pH [ 5.23, corresponds to the two-electron, one-proton
process (Scheme 1) [26]. Electrochemical oxidation of
various species in the presence different nucleophiles
indicates that the peak current ratio (I /I ) decreases
pC pA
upon increasing power nucleophilicity of nucleophiles [31,
?
2]. In other words, in pH upper than 5.23, 1H loses its
3
proton and converts to its neutral form (1) therefore, power
nucleophilicity of it increases which causes increasing rate
of dimerization as following chemical reaction and the
peak current ratio (IpC1/IpA1) decreases.
3
Controlled-potential coulometry 80 cm containing
0.30 mmol of 1 in aqueous solution (0.1 M sodium
hydroxide, pH 13) at -0.05 V vs. Ag/AgCl was performed
(Fig. 9). All three anodic and cathodic peaks (A , A , and
1 0
Electrochemical behavior in strong alkaline pHs
C ) disappear when the charge consumption becomes about
0
-
2e per molecule of 1 and the final product was analyzed
using mass spectroscopy (MS).
(
pH 10–13)
Figure 6 shows cyclic voltammogram 1.0 mM of 2,5-
DEMA (1) in aqueous solution containing 0.01 M sodium
hydroxide (pH 12). As it is shown in this figure, at the scan
rate of 100 mV/s, the CV exhibits the feature of an irre-
Our experiences on electrochemical oxidation of amines
at various conditions [24–28], diagnostic criteria of cyclic
voltammetry and controlled-potential coulometry (Figs. 6,
7, 8, 9), consumption of two electrons per molecule of 1
and the mass spectrum of isolated product (m/z = 551)
allow us to propose ECEC pathway for the electrochemical
oxidation of 2,5-DEMA (1) in strongly alkaline pHs
(Scheme 2). As is shown in Scheme 2, the electrochemical
oxidation of 2,5-DEMA (1) leads to the formation of p-
versible electron-transfer process with an anodic peak (A ) at
1
-
0.015 V vs. Ag/AgCl, which corresponds to the transfor-
?
mation of 1 to its p-quinonediimine (1ox ) [26]. The cyclic
voltammogram behavior strongly depends on the scan rate,
and the C peak (counterpart of the A ) appears and its
1
1
?
current increases with increasing the scan rates. In addition,
quinonediimine (1ox ). Via a Michael addition reaction
?
with hydroxide ion and aromatization, 1ox is converted to
height of the cathodic peak C decreases by increasing the
0
?
potential scan rate. This CV shows that 1ox is unstable and
2a. The oxidation of compound 2a is easier than the oxi-
dation of 1 by virtue of the presence of an electron-
donating group [30]. In the next step, the generated p-
participates to following chemical reaction. The second
cycle of the cyclic voltammogram for this solution (Fig. 6,
?
curve b) shows a new anodic peak (A ) at -0.33 V. The
0
quinonediimine 2ox is subjected to another Michael
cathodic peak C and its corresponding anodic peak (A ) in
0
addition reaction with 1 and converts to the final product
2b. It should be noted that, in the mass spectra of 2b, the
molecular ions [M ? 4H] was recorded (Fig. 10). This
mass is related to protonation of the quinonic moiety and
amino groups. Obtained results show that in the power
alkaline solution (pH 10–13) rate of the hydroxylation is
faster than hydrolysis and dimerization.
0
the second cycle of the cyclic voltammogram correspond to
the reduction and oxidation of the product that is produced at
the surface of the GC electrode.
?
It is probably in the following chemical reaction 1ox
hydrolyzed and converts to p-benzoquinone 1a
(
Scheme 1). To synthesize 1a, using method which is
1
23

Mechanistic study of electrochemical oxidation
Scheme 1
NH3
NH2
O
O
EtO
EtO
EtO
+
-
-
2H , -2e
Hydrolysis
Strong acidic pHs
pH = 1- 3
OEt
OEt
OEt
NH
O
N
O
1a
1Hox2+
1
H22+
O
N
Intermediate pHs:
a) pH = 4 - 5.2
EtO
OEt
NH
O
NH2
EtO
NH
OEt
EtO
OEt
+
-
Trimerization
)
1
-
2H , -2e
OEt
HN
EtO
N
O
2) Hydrolysis
NH
O
O
EtO
OEt
ox+
1
c
1
1
H+
N
O
O
N
EtO
b) pH = 5.3 - 9
NH
OEt
O
NH2
EtO
NH
EtO
HN
OEt
+
-
Trimerization
1)
-
H , -2e
OEt
EtO
N
O
2) Hydrolysis
OEt
N
O
O
EtO
OEt
ox+
1
c
1
1
H+
N
O
Conclusion
potential coulometry. The results show that 2,5-DEMA (1)
is oxidized in aqueous solutions to its p-quinonediimine
?
(1ox or 1oxH ). Obtained the peak current ratio (IpC1/
2?
In the present work, electrochemical oxidation of 2,5-die-
thoxy-4-morpholinoaniline (2,5-DEMA) has been studied
in various pHs using cyclic voltammetry and controlled-
IpA1) show that the produced p-quinonediimine is unstable
in all pHs and participate in hydrolysis, trimerization, and
123

H. Beiginejad, D. Nematollahi
Fig. 6 CVs of a the first and b the second cycle of 1.0 mM 2,5-
DEMA (1) in aqueous solution containing 0.01 M sodium hydroxide
-
1
Fig. 8 Normalized cyclic voltammograms of 2,5-DEMA in aqueous
solution containing 0.01 M sodium hydroxide (pH 12) at various
concentrations. Scan rate = 250 mV s , t = 25 ± 1 °C
(
pH 12); scan rate: 100 mV s , t = 25 ± 1 °C
-1
Fig. 7 a CV 1.0 mM of 2,5-DEMA and b cyclic voltammogram
.0 mM of 1a in aqueous solution containing 0.01 M sodium
1
-
1
hydroxide (pH 12); scan rate: 100 mV s , t = 25 ± 1 °C
Fig. 9 Cyclic voltammograms of 2,5-DEMA (0.30 mmol) during
controlled potential coulometry at -0.05 V vs. Ag/AgCl in aqueous
solution containing 0.1 M NaOH, after the consumption of: a 0 C,
hydroxylation reactions depend on solution’s pH. The
reaction mechanisms for the electrochemical oxidation of
-1
b 11 C, c 22 C, d 33 C, e 44 C, and f 55 C. Scan rate: 50 mV s
,
t = 25 ± 1 °C. Inset: variation of peak current (IA1) vs. consumed
charge
2
,5-DEMA (1) in different pHs are presented in Schemes 1
and 2. Instability of the produced p-quinonediimine
depends on the its structure, higher nucleophilicity of 2,5-
DEMA (1) and pH of solution. The electrochemical oxi-
dation of 2,5-DEMA (1) at various pHs shows that rate of
following chemical reaction indicates final product. In the
power acidic solution rate of hydrolysis is faster than
hydroxylation and dimerization. In the intermediate pHs
rate of the dimerization is faster than hydrolysis and
hydroxylation, and in the power alkaline solution rate of
the hydroxylation is faster than hydrolysis and dimeriza-
tion. The effect of charge of reaction site (C ) and N =C
1
were performed using density functional theory (DFT)
B3LYP level of theory and 6-311?G(p,d) basis set.
Materials and methods
Cyclic voltammetry and controlled-potential coulometry
were performed using micro Autolab potentiostat/galva-
nostat. The working electrode used in the voltammetry
experiments was a glassy carbon disk (1.8 mm diameter)
and a platinum wire was used as the counter electrode. The
1
1
bond orders (Wiberg bond indices, WBI) on the stability of
produced p-quinonediimine were studied. Calculations
1
23

Mechanistic study of electrochemical oxidation
Scheme 2
Strong alkaline pHs (pH = 10 - 13)
NH
NH2
NH2
NH
OH
OH
EtO
H , -2e-
EtO
EtO
EtO
H , -2e-
+
Hydroxylation
+
-
-
OEt
OEt
OEt
OEt
N
O
N
O
N
O
N
O
1ox+
1
2a
2ox
NH2
HO
OEt
NH
NH
NH2
EtO
OH
OEt
Aromatization
EtO
EtO
N
O
OEt
OEt
N
O
N
N
O
+
EtO
O
2ox
2b
1
Fig. 10 Mass spectrum of
separated product 2b from
electrochemical oxidation of
2,5-DEMA in aqueous solution
containing 0.1 M NaOH
NH
2
HO
EtO
OEt
NH
OEt
N
O
N
EtO
O
2
b
working electrode used in controlled-potential coulometry
2
was an assembly of four ordinary carbon rods (31 cm
Computational study
from KIGCO, Mashhad, Iran), placed as single rods in the
edges of a square with a distance of 3 cm. The carbon rods
are washed with acetone and distilled water before starting
electrolysis. A large platinum gauze was used as counter
electrode. The experiment was carried out at a temperature
of 25 ± 1 °C. The working electrode potentials were
measured vs. standard Ag/AgCl (all electrodes from AZAR
Electrode). Also all chemicals were reagent grade materi-
als, from Aldrich and E. Merck and were used without
further purification.
Using Gaussian 03 [33] the geometries of all species
investigated here, in the gas-phase were fully optimized at
the DFT (B3LYP) level of theory [34, 35]. The standard
6-311?G** basis set was used for geometry optimiza-
tion and vibrational frequency analyses. A starting
molecular- mechanics structure for the ab initio calcula-
tions was obtained using the HyperChem 5.02 program
?
(MM method). [36]. Also natural bond orbital (NBO)
analyses [37] were carried out at the mentioned levels of
theory.
123

H. Beiginejad, D. Nematollahi
Electroorganic synthesis of 2,5-diethoxy-p-benzoquinone
3
1a) A phosphate buffer solution (80 cm , 0.2 M, pH 2.0)
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(
containing 0.05 mmol of 2,5-diethoxy-4-morpholinoani-
line (1) was subjected to electrolysis at 0.40 V vs. Ag/AgCl
in a divided cell. The electrolysis was terminated when the
current decayed to 5 % of its original value. The product
was extracted by ethyl acetate and was washed with water.
After drying, the product was characterized by IR, and
structure of 1a was confirmed by comparing the results
with the literature report [26].
1
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2b, C H N O ) Alkaline solution (80 cm ) containing
(
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42
4
7
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(2009) Electrochim Acta 54:7407
2
2
2
0
4
.1 M NaOH (pH 13.0) and 0.05 mmol of 2,5-diethoxy
6. Beiginejad H, Nematollahi D (2013) Electrochim Acta 114:242
7. Beiginejad H, Nematollahi D (2014) J Org Chem 79:6326
8. Beiginejad H, Nematollahi D, Varmaghani F, Bayat M (2013) J
Electrochem Soc 160:H469
-morpholinoaniline (1) was subjected to electrolysis at
0.05 V vs. Ag/AgCl in a divided cell. The electrolysis
-
was terminated when the current decayed to 5 % of its
original value. After evaporation of water, final product
was extracted with ethanol and analyzed using mass
spectroscopy (MS).
29. Kirdant AS, Magar BK, Chondhekar TK (2012) J Chem Biol
Phys Sci 2:147
3
0. Beginejad H, Nematollahi D, Varmaghani F, Shayani-Jam H
2013) Monatsh Chem 144:1481
(
3
1. Beiginejad H, Nematollahi D, Varmaghani F, Bayat M (2013) J
Electrochem Soc 160:G3001
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