Inhibition of Copper Corrosion with N-Arylaminotriazoles in Aqueous Chloride Solutions and in Air

Article abstract of DOI:10.1134/S1070427220080078

Abstract: A series of 3-(N-arylamino)-5-amino-1Н-1,2,4-triazoles were prepared by the reaction of S,S-dimethyl cyanodithioimidocarbamate with appropriate anilines. The inhibiting effect of the products on the corrosion of copper of M1 grade in acidic and neutral chloride-containing media was studied using electrochemical and accelerated electroless methods. The maximal degree of protection ensured by commercially available 3,5-diamino-1H-1,2,4-triazole and the synthesized 3-phenylamino, 3-(4-methylphenylamino), 3-(4-chlorophenylamino), and 3-(3-chlorophenylamino) derivatives of 5-amino-1Н-1,2,4-triazole reaches 70–87%. In acid solutions, the synthesized compounds show higher performance than the 3,5-diamino derivative, ensuring up to 92–96% protection. Similar results were obtained in experiments in a salt fog chamber.

Full text of DOI:10.1134/S1070427220080078

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2020, Vol. 93, No. 8, pp. 1152–1159. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Prikladnoi Khimii, 2020, Vol. 93, No. 8, pp. 1118–1126.
APPLIED ELECTROCHEMISTRY
AND METAL CORROSION PROTECTION
Inhibition of Copper Corrosion with N-Arylaminotriazoles
in Aqueous Chloride Solutions and in Air
D. S. Shevtsova, Kh. S. Shikhalieva,*, E. S. Komarovaa,
A. A. Kruzhilinb, G. O. Kipriyanovaa, A. Yu. Potapova,
I. D. Zartsyna, O. A. Kozaderova,
Ch. Prabhakarc, and A. Tripathic
a Voronezh State University, Voronezh, 394018 Russia
b Voronezh State Agrarian University, Voronezh, 394087 Russia
c National Institute of Technology, Kurukshetra, Haryana, 136119 India
*e-mail: shikh1961@yandex.ru
Received May 21, 2019; revised March 16, 2020; accepted May 25, 2020
Abstract—Aseries of 3-(N-arylamino)-5-amino-1Н-1,2,4-triazoles were prepared by the reaction of S,S-dimethyl
cyanodithioimidocarbamate with appropriate anilines. The inhibiting effect of the products on the corrosion
of copper of M1 grade in acidic and neutral chloride-containing media was studied using electrochemical and
accelerated electroless methods. The maximal degree of protection ensured by commercially available 3,5-diamino-
1H-1,2,4-triazole and the synthesized 3-phenylamino, 3-(4-methylphenylamino), 3-(4-chlorophenylamino),
and 3-(3-chlorophenylamino) derivatives of 5-amino-1Н-1,2,4-triazole reaches 70–87%. In acid solutions, the
synthesized compounds show higher performance than the 3,5-diamino derivative, ensuring up to 92–96% protection.
Similar results were obtained in experiments in a salt fog chamber.
Keywords: in situ synthesis, copper, corrosion inhibitors, chlorides, 3-(N-arylamino)-5-amino-1Н-1,2,4-triazoles
DOI: 10.1134/S1070427220080078
Organic corrosion inhibitors are widely used for
reducing the corrosion rate in operation of metal items in
various media. Azoles are widely used for the protection
of copper and its alloys [1, 2]. Despite a large set of the
already known compounds with the proved protective
effect, synthesis of new promising corrosion inhibitors
for a specific metal in a specific medium and of versatile
inhibitors for a series of metals and alloys used under
various conditions is still a topical research field [3, 4].
Often the performance of such inhibitors is enhanced by
introducing a hydrophobic substituent into the triazole
ring. This reduces their solubility in water and can lead
to disturbances in the equipment operation, in particular,
due to the formation of particle agglomerates, followed
by plugging of conducting channels [9, 10]. Preparation
of corrosion inhibitors with high protective performance
and satisfactory solubility is an important scientific and
practical problem.
This study was aimed at preparing 3-(N-arylamino)-
5-amino-1Н-1,2,4-triazoles and at evaluating their
ability to protect copper in neutral and acidic aqueous
solutions containing chloride ions in comparison with
the commercially available analogs.
Among azoles, 1,2,3-benzotriazole is the most stud-
ied copper corrosion inhibitor [5–7]; it is still widely
used for the protection of nonferrous metals. However,
not only benzotriazole derivatives, but also some other,
more hydrophilic triazoles attract researchers’ attention
for the protection of copper and its alloys. For example,
3-amino-1,2,4-triazole prevents the pitting formation on
copper in a borate buffer solution containing chlorides
and sulfates more efficiently than benzotriazole does [8].
EXPERIMENTAL
Commercially available 3,5-diamino-1H-1,2,4-
triazole (1a) (Sigma–Aldrich, CAS 1455-77-2) was
1152

INHIBITION OF COPPER CORROSION WITH N-ARYLAMINOTRIAZOLES
1153
used. S,S-Dimethyl cyanodithioimidocarbamate was
prepared by the procedure described in [11].
inhibitors (сinh = 0.01, 0.10, and 1.00 mM) were added.
After the new value of Еcor was attained, the polarization
curves were recorded at the potential sweeping rate
of 0.2 mV s–1 in the cathodic and anodic directions.
The activation potential (Еact) was determined from
a sharp increase in the current in the anodic portion
of the polarization curve with the subsequent visual
identification of pitting on the electrode surface. The
uncertainty in measuring Еact was 0.03 V.
Synthesis of 3-(N-arylamino)-5-amino-1Н-1,2,4-
triazoles 1b–1e (general procedure). Appropriate
aniline (0.1 mol) was added to 0.1 mol of S,S-dimethyl
cyanodithioimidocarbamate. The mixture was refluxed
for3–4hinisopropylalcohol.Aftertheamineconversion
was complete, 0.2 mol of hydrazine hydrate was added,
and the mixture was refluxed for 1 h. The precipitate
was filtered off and washed with hot isopropanol.
To calculate the corrosion rate on reaching the steady
state, we performed the electrode polarization in the
interval ±30 mV relative to Еcor in the potentiodynamic
mode at a sweeping rate of 0.2 mV s–1.
1
The H NMR spectra were recorded with a Bruker
DRX-500 device (operating frequency 500 and
125.8 MHz) in the pulse Fourier mode in DMSO-d6.
The chemical shifts were determined relative to the
residual proton signals of the deuterated solvent or to
internal tetramethylsilane. Chromatographic analysis
of the compound purity was performed with an Agilent
1260 Infinity liquid chromatograph equipped with
UV and mass detectors (Agilent 6230 TOF LC/MS
high-resolution time-of-flight detector, electrospray
ionization). Chromatographing conditions: Gemini C18
column (4.6 × 50 mm); sorbent particle size 5 μ m;
linear gradient elution; mobile phase: eluent А, MeCN–
Н2О, 2.5 : 97.5, 0.1% CF3COOH; eluent В, MeCN,
0.1% CF3COOH; flow rate 3.75 mL min–1; column
temperature 40°С; sample volume 1.5 μ L. The melting
points were determined with a Stuart SMP30 device.
Intermediate monitoring of the degree of conversion and
product purity was performed by TLC with Silufol UV-
254 plates. The chloroform–methanol system was used
as an eluent; the chromatograms were developed under
UV light and with iodine vapor.
The polarization resistance (Rp) was determined as
the slope of the polarization curve in point Еcor in the
coordinates ΔE (E–Еcor)–i. We obtained the dependence
in the coordinates 2.3Rpi–ΔE. The coefficients ba and bc
(Tafel slopes of the anodic and cathodic half-reactions)
were determined using the TableCurve 2D program as
the approximation parameters of the equation
.
The corrosion rate was calculated by the equation icor
=
B/Rp, taking into account the coefficients obtained. Such
procedure for calculating the corrosion rate was suggested
for the first time by Mansfeld [12] and was tested for
copper in a neutral chloride solution [13, 14]. The
inhibiting performance (%) of 5-amino-1H-1,2,4-triazole
derivatives was evaluated by the degree of protection:
Electrochemical studies were performed in a borate
buffer solution (pH 7.40) based on distilled water with
the addition of 10 mM NaCl. Polarization curves were
recorded in a three-electrode electrochemical cell with
unseparated electrode compartments with an IPC-PRO
potentiostat. The working electrode made of copper of
M1 grade (surface area 0.75 cm2) was preliminarily
cleaned with sandpaper (fineness up to K3000) and
degreased with acetone. The electrode potentials
(Е) were measured vs. silver chloride electrode and
converted to the standard hydrogen scale. The auxiliary
electrode was made of platinum.
icor,0 icor,inh
Zinh

100,
icor,0
where icor,0 and icor,inh are the corrosion current densities
without inhibitor and in its presence, respectively.
Salt fog chamber tests simulated the atmospheric
corrosion of copper and were aimed at revealing
the inhibiting effect of 5-amino-1H-1,2,4-triazole
derivatives for protecting copper items in the periods
between operation runs. Tests were performed with
copper plates that were preliminarily cleaned with
sandpaper of different grit sizes, polished, and degreased
with acetone. The protective film of the inhibitors was
deposited by keeping the plates at 60°C for 60 min
in an aqueous solution containing inhibitors. The
specimens were dried and placed in a chamber in which
After the copper oxide film formedin air was removed
at Е = –0.60 V for 15 min, the potentiostat was switched
off until the free corrosion potential was attained (Еcor).
Then, a NaCl solution (сCl– = 10 mM) and the tested
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SHEVTSOV et al.
Scheme 1. Synthesis of 3-(N-arylamino)-5-amino-1Н-1,2,4-triazoles.
H2N–NH2
i-PrOH
1b–1e
R = Ph (1b); 4-Me-C6H4 (1c); 4-Cl-C6H4 (1d); 3-Me-C6H4 (1e).
The parameter k0 was 40–44 g m–2 day–1. The
corrosion-protective effect was studied for the systems
with the inhibitor concentration of 1.0, 5.0, and
10.0 mM.
a 5% aqueous NaCl solution [pH 6.5–7.2, GOST (State
Standard) R 52763–2007] was sprayed every hour and
the relative air humidity was maintained at 95–100%.
The specimens were examined visually 3 times a day to
determine the time in which the first corrosion damage
appeared (τcor).
RESULTS AND DISCUSSION
Corrosion tests were performed in accordance with
GOST (State Standard) 9.905–82, Methods of Corrosion
Tests, using copper plates of area S = 20 × 50 mm2 and
thickness d = 0.2 mm. Each specimen was preliminarily
polished with fine sandpaper (K1000), washed with
distilled water and ethanol, and dried with filter paper.
Seven-day experiments were performed with three
specimens simultaneously in a 1% aqueous HCl solution
under the conditions of natural aeration without stirring.
After the tests, the plates were washed with distilled
water and treated in accordance with GOST 9.907–83,
Methods for Removing Products after Corrosion Tests.
The corrosion rate was determined from the specimen
weight loss and was calculated by the formula
3-(N-Arylamino)-5-amino-1Н-1,2,4-triazoles
1b–1e were synthesized in two steps: by the reaction
of the appropriate anilines with S,S-dimethyl
cyanodithioimidocarbamate, followed by the reaction
of the intermediates formed with hydrazine hydrate.
Monitoringoftheconditionsforpreparingaminotriazoles
1b–1e has shown that N-cyano-1-carbimidothioates are
formed almost quantitatively. With accurate monitoring
of the conversion of the starting compounds, it is not
necessary to isolate and purify the intermediate N-cyano-
1-carbimidothioates, andhydrazinehydrateinthesecond
step of the process can be added directly to the reaction
vessel. This allows reduction of the product loss and
of the total time for preparing the desired compounds.
By the one-pot process, we prepared 3-(N-arylamino)-
5-amino-1Н-1,2,4-triazoles 1b–1e (Tables 1, 2) whose
purity and characteristics were virtually the same as
those of the products prepared in steps (Scheme 1).
m0  m
St
k 
,
where m0 and m are the specimen weights before and
after corrosion tests, respectively.
The 1H NMR spectra of the synthesized compounds
(Table 3) contain characteristic signals of the NH proton
of the corresponding triazole rings at 11.05–11.25 ppm.
The proton of secondary amino groups bonded to
benzene and triazole rings gives a signal at 8.40–
8.92 ppm. The protons of the aromatic systems give
triplets and doublets at 6.70–7.75 ppm.
The inhibiting performance of the 5-amino-1H-1,2,4-
triazole derivatives was evaluated by the inhibition
factor
k0
 
kinh
and degree of protection (%)
On adding the inhibitors to a chloride solution, Еcor
changed differently (Table 4). On adding 3,5-diamino-
1H-1,2,4-triazoles to concentrations сinh ≤ 0.10 mM
(3-(4-chlorophenylamino)-5-amino-1 -1,2,4-triazole, up
to сinh = 1.00 mM), Еcor changed insignificantly. Only for
3-phenylamino-5-amino-1H-1,2,4-triazole we observed
k0  kinh
Zk 
100,
k0
wherek0 andkinh arethecorrosionratesinanHClsolution
without inhibitor and in its presence, respectively.
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INHIBITION OF COPPER CORROSION WITH N-ARYLAMINOTRIAZOLES
Table 1. Structures of the 3-(N-arylamino)-5-amino-1Н-1,2,4-triazoles studied
1155
Designation
Name
Structural formula
1a
3,5-Diamino-1H-1,2,4-triazole
1b
1c
1d
3-Phenylamino-5-amino-1Н-1,2,4-triazole
3-(4-Methylphenylamino)-5-amino-1Н-1,2,4-triazole
3-(4-Chlorophenylamino)-5-amino-1Н-1,2,4-triazole
1e
3-(3-Chlorophenylamino)-5-amino-1Н-1,2,4-triazole
Table 2. Physicochemical characteristics of the synthesized 3-(N-arylamino)-5-amino-1Н-1,2,4-triazoles
Empirical
formula
Compound
Calculated Found
Tm, °C
Yield, %
3-Phenylamino-5-amino-1Н-1,2,4-triazole
C8H9N5
175.0961 175.0963
190.1065 190.1107
209.0511 209.0541
209.0511 209.0527
166–169
162–164
161–163
158–160
95
84
77
73
3-(4-Methylphenylamino)-5-amino-1Н-1,2,4-triazole C9H11N5
3-(4-Chlorophenylamino)-5-amino-1Н-1,2,4-triazole C8H8ClN5
3-(3-Chlorophenylamino)-5-amino-1Н-1,2,4-triazole C8H8ClN5
an anodic shift of Еcor by more than 50 mV. For the other
additives, Еcor shifted in the cathodic direction.
higher, and at still higher potentials the polarization
curves become indiscernible. The cathodic portion
of the polarization curve has a wider (by 20–30 mV)
polarizability range relative to the control experiment.
With an increase in the concentration to 0.10 mM, the
initial portion of the anodic polarization curve is shifted
to zero current densities until a maximum at a potential
of ≈0.38 V is reached. The further course of the anodic
polarization curve is similar to the control experiment.
In the cathodic portion, the polarizability range of the
copper electrode increases by more than 0.10 V.
The results of electrochemical tests are not given for
3-(3-chlorophenylamino)-5-amino-1Н-1,2,4-triazole,
because it decomposes in the step of the preparation of
the working solution for the subsequent dilution, which
restricts its applicability.
The electrochemical behavior of the copper electrode
in the presence of 3,5-diamino-1H-1,2,4-triazole
(Fig. 1) differs from that observed with compounds
1b–1d. The current density in the anodic portion of the
polarization curve up to a concentration of 0.01 mM
first varies similarly to the control experiment without
inhibitor. With a further increase in the polarization, the
current density in the interval ≈0.21–0.40 V becomes
However, an intense increase in the current density
is observed in the anodic portion of the polarization
curve on introducing 1.00 mM 3,5-diamino-1H-1,2,4-
triazole. The current passed through a maximum at a
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SHEVTSOV et al.
i, μ A cm–2
relative to the control experiment without treatment with
1a (Table 5). The value of τcor = 2 h for the concentration
of 10.0 mM is considered as similar to that in the control
experiment without adding 1a at 1-h interval between
visual examinations. On the other hand, tests in an acid
show that the degree of protection (Zk) increases as the
inhibitor concentration is increased in the interval 1.00–
10.0 mM (Table 5).
The trends observed in the anodic and cathodic por-
tions of the polarization curves recorded in the pres-
ence of 3-phenylamino-5-amino-1Н-1,2,4-triazole and
3-(4-methylphenylamino)-5-amino-1Н-1,2,4-triazole are
similar (Figs. 2, 3), despite the difference in Еcor. For both
additives, no current maximum is observed in the anodic
polarization curve. The shift of Еact toward positive values
exceeds 0.20 V [except the concentration of 0.10 mM for
3-(4-methylphenylamino)-5-amino-1Н-1,2,4-triazole].
Also, the interval of the cathode polarizability in the ca-
thodic portions of the polarization curves increases by
more than 0.10 V for 3-phenylamino-5-amino-1Н-1,2,4-
triazole and 0.25 V for 3-(4-methylphenylamino)-5-
amino-1Н-1,2,4-triazole.
E, V
Fig. 1. Anodic and cathodic polarization curves of copper in a
borate buffer solution (рН 7.4) + 10 mM NaCl (1, 1′) without
inhibitor and with the addition of (2, 2′) 0.01, (3, 3ʹ) 0.10, and
(4, 4ʹ) 1.00 mM 3,5-diamino-1H-1,2,4-triazole.
more negative potential. The current density exceeded
that in the control experiment by a factor of up to 5. The
cathodic polarization curve is similar to that recorded in
the control experiment.
The revealed trends in the polarization curves allow
prediction of the protective effect of compounds 1b–1e
in neutral media. The inhibiting effect increases with
the concentration. Corrosion experiments in a salt fog
chamber also demonstrate more than a 20-fold protective
effect for 1b, 1c, and 1e and more than a 10-fold effect
for 1d relative to the unprotected metal, irrespective of
the inhibitor concentration. It should be noted that, for
3-phenylamino-5-amino-1Н-1,2,4-triazole, the results
in the concentration interval 1–10 mM are similar,
whereas for 3-(4-methylphenylamino)-5-amino-1Н-
The degree of protection (Zinh) ensured by
3,5-diamino-1H-1,2,4-triazole in neutral chloride-
containing solutions monotonically decreases with an
increase in the substance concentration from 0.01 to
1.00 mM (Table 4).Atmospheric tests performed in a salt
fog chamber with monitoring τcor in the concentration
interval 1.00–10.0 mM revealed no protective effect
Table 3. 1Н NMR spectra of the synthesized 3-(N-arylamino)-5-amino-1Н-1,2,4-triazoles
Compound
1H NMR spectrum, δ, ppm (J, Hz)
3-Phenylamino-5-amino-1Н-1,2,4-triazole
5.87 (2H, br.s, NH2), 6.71 (1H, t, J = 7.3, CH-arom.), 7.15 (2H, t, J =
7.8, CH-arom.), 7.49 (2H, d, J = 7.9, CH-arom.), 8.62 (s, 1H, NH),
11.20 (br.s, 1H, NH-triaz.
3-(4-Methylphenylamino)-5-amino-1Н-1,2,4-triazole 2.18 (3H, s, CH3), 5.80 (2H, br.s, NH2), 6.71 (2H, d, J = 7.9,
CH-arom.), 7.38 (2H, d, J = 7.9, CH-arom.), 8.40 (s, 1H, NH), 11.05
(br.s, 1H, NH-triaz.
3-(4-Chlorophenylamino)-5-amino-1Н-1,2,4-triazole 5.90 (2H, br.s, NH2), 7.12 (2H, t, J = 7.8, CH-arom.), 7.57 (2H, d, J =
7.9, CH-arom.), 8.60 (s, 1H, NH), 11.15 (br.s, 1H, NH-triaz.
3-(3-Chlorophenylamino)-5-amino-1Н-1,2,4-triazole 5.90 (2H, br.s, NH2), 6.71 (1H, d, CH-arom.), 7.15 (1H, t,
J = 7.8, CH-arom.), 7.31 (1H, d, J = 7.9, CH-arom.), 7.74 (1H, s, CH-
arom.); 8.92 (s, 1H, NH), 11.25 (br.s, 1H, NH-triaz.
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INHIBITION OF COPPER CORROSION WITH N-ARYLAMINOTRIAZOLES
1157
Table 4. Results of electrochemical measurements of copper in a borate buffer solution (рН 7.4) + 10 mM NaCl with the
addition of 5-amino-1H-1,2,4-triazoles
Free
Inhibitor
concentration
cinh, mM
Polarization
resistance Rp,
kΩ cm2
Corrosion
Degree of
corrosion
potential
Ecor, V
Compound
current density protection
icor, μ A cm–2
Zinh, %
No inhibitor
–
0.172
0.185
0.175
0.090
0.246
0.216
0.117
0.116
0.141
0.188
41.9 ± 4.6
58.6 ± 5.2
32.0 ± 4.3
39.9 ± 3.8
61.3 ± 7.2
72.6 ± 9.6
58.5 ± 6.2
99.9 ± 9.4
221 ± 13
1.20 ± 0.3
0.36 ± 0.17
0.46 ± 0.13
0.70 ± 0.2
0.62 ± 0.16
0.44 ± 0.12
0.81 ± 0.15
0.25 ± 0.09
0.41 ± 0.13
0.16 ± 0.06
–
3,5-Diamino-1H-1,2,4-triazole
0.01
0.10
1.00
0.10
1.00
0.10
1.00
0.10
1.00
70
62
42
48
63
33
79
66
87
3-Phenylamino-5-amino-1Н-1,2,4-triazole
3-(4-Methylphenylamino)-5-amino-1Н-1,2,4-
triazole
3-(4-Chlorophenylamino)-5-amino-1Н-1,2,4-
triazole
340 ± 18
Table 5. Results of corrosion tests in an acid and in a salt fog chamber
Time to the
appearance
of corrosion
τcor, h
Inhibitor
concentration
cinh, mM
Corrosion
Degree of
protection
Zk, %
Inhibition
coefficient γ
Compound
rate,
g m–2 day–1
No inhibitor
–
1.0
44.0
10.4
8.5
1.0
1.3
1.6
4.0
2.4
2.1
22
–
3
4
3,5-Diamino-1H-1,2,4-triazole
20.4
35.5
74.7
57.7
52.5
95.5
22.8
78.8
92.2
18.4
53.0
79.3
51.1
92.9
96.2
5.0
4
10.0
1.0
3.3
2
3-Phenylamino-5-amino-1Н-1,2,4-
triazole
18.6
20.9
2.0
60
62
61
66
80
122
36
46
62
70
90
93
5.0
10.0
1.0
3-(4-Methylphenylamino)-5-amino-1Н-
1,2,4-triazole
17.1
4.7
1.3
4.7
12.8
1.2
2.1
4.8
2.0
14.2
26.3
5.0
10.0
1.0
1.7
3-(4-Chlorophenylamino)-5-amino-1Н-
1,2,4-triazole
15.3
8.8
5.0
10.0
1.0
3.9
3-(3-Chlorophenylamino)-5-amino-1Н-
1,2,4-triazole
4.4
5.0
0.6
10.0
0.3
1,2,4-triazole the protective effect is stronger and
increases with the concentration.
The anodic portion of the polarization curve of copper
with the addition of 0.10 mM 3-(4-chlorophenylamino)-
5-amino-1Н-1,2,4-triazole differs from all the other
dependences obtained (Fig. 4). In the initial portion, up
to a potential of ≈0.27 V, the current density is lower
The corrosion inhibition was also revealed in acid
solutions. The degree of protection increases in the
concentration interval 1–10 mM and reaches 92–95%.
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SHEVTSOV et al.
i, μ A cm–2
tested concentrations of 3-(4-chlorophenylamino)-5-
amino-1Н-1,2,4-triazole.
The corrosion current densities obtained in the
presence of 3-(4-chlorophenylamino)-5-amino-1Н-
1,2,4-triazolearethelowestamongthetestedcompounds
at comparable concentrations. The results of corrosion
tests in a salt fog chamber are comparable with the
experimental data for the compounds considered above.
More than 50% protective effect in an acid medium was
obtained only at the 3-(4-chlorophenyl)-5-amino-1Н-
1,2,4-triazole concentration of no less than 5 mM.
E, V
CONCLUSIONS
3-Phenylamino,
3-(4-methylphenylamino),
Fig. 2. Anodic and cathodic polarization curves of copper in a
borate buffer solution (рН 7.4) + 10 mM NaCl (1, 1′) without
inhibitor and with the addition of (2, 2′) 0.10 and
(3, 3ʹ) 1.00 mM 3-phenylamino-5-amino-1H-1,2,4-triazole.
3-(4-chlorophenylamino), and 3-(3-chlorophenylamino)
derivatives of 5-amino-1Н-1,2,4-triazole were prepared
in more than 75% yield by the optimized cascade one-
pot reaction of S,S-dimethyl cyanodithioimidocarbamate
with arylamines and hydrazine.
than that observed in the control experiment. With
a further increase in the potential, the current density
intensely increases to 250 μ A cm–2 without passing
through a maximum. At a concentration of 1.00 mM, a
long portion with the current close to zero is observed
in the anodic portion of the polarization curve up to a
potential of 0.57 V. No maximum of the current density
is observed. The value of Еact is the same as in the control
experiment. In the cathodic portions of the polarization
curves, the interval of the electrode polarizability
increases by more than 0.10 V in the presence of the
The compounds synthesized exert an inhibiting effect
on the copper corrosion in neutral and acidic chloride-
containing media. In a neutral aqueous solution, the
maximaldegreeofprotectioniscloseforallthecompounds
studied and reaches 70–87%. For 3,5-diamino-1H-
1,2,4-triazole, the protective performance decreases
with an increase in its concentration in solution in the
interval 0.01–1.00 M. In an acid medium, the degree of
protection for the compounds synthesized exceeds that
ensured by the commercially available 3,5-diamino-1H-
i, μ A cm–2
i, μ A cm–2
E, V
E, V
Fig. 3. Anodic and cathodic polarization curves of copper in a
borate buffer solution (рН 7.4) + 10 mM NaCl (1, 1′) without
inhibitor and with the addition of (2, 2′) 0.10 and (3, 3ʹ) 1.00 mM
3-(4-methylphenylamino)-5-amino-1H-1,2,4-triazole.
Fig. 4. Anodic and cathodic polarization curves of copper in a
borate buffer solution (рН 7.4) + 10 mM NaCl (1, 1′) without
inhibitor and with the addition of (2, 2′) 0.10 and (3, 3ʹ) 1.00 mM
3-(4-chlorophenylamino)-5-amino-1H-1,2,4-triazole.
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INHIBITION OF COPPER CORROSION WITH N-ARYLAMINOTRIAZOLES
1159
https://doi.org/10.1016/j.corsci.2010.05.002
1,2,4-triazole and reaches 92–96% for 3-phenylamino,
3-(4-methylphenylamino),and3-(3-chlorophenylamino)
derivatives at their concentration of 10 mM. The results
of salt fog chamber tests are similar to those obtained in
an acid medium. The time in which the first corrosion
products appear exceeds that reached with 3,5-diamino-
1H-1,2,4-triazole by a factor of 9–60 depending on the
concentration and structure of the new derivatives.
3. Khiati, Z., Othman, A.A., Sanchez-Moreno, M.,
Bernard, M.-C., Joiret, S., Sutter, E.M.M., and Vivier, V.,
Corros. Sci., 2011, vol. 53, pp. 3092–3099.
https://doi.org/10.1016/j.corsci.2011.05.042
4. Finšgar, M., Corros. Sci., 2013, vol. 77, pp. 350–359.
https://doi.org/10.1016/j.corsci.2013.08.026
5. Skrypnikova, E.A., Kaluzhina, S.A., andAgafonova, L.E.,
Int. J. Corros. Scale Inhib., 2014, vol. 3, no.1, pp. 59–65.
https://doi.org/10.17675/2305-6894-2014-3-1-059-065
The use of 3-(3-chlorophenylamino)-5-amino-
1Н-1,2,4-triazole as a copper corrosion inhibitor is
appropriate when it is directly dissolved in the working
medium because of high probability of decomposition
in the step of preparing concentrates with the substance
concentration higher than 10 mM.
6. Dugdale, I. and Cotton, J.B., Corros. Sci., 1963, vol. 2,
no. 1, pp. 69–75.
https://doi.org/10.1016/s0010-938x(63)80001-3
7. Poling, G.W., Corros. Sci., 1970, vol. 10, pp. 359–370.
https://doi.org/10.1016/s0010-938x(70)80026-9
FUNDING
8. Es-Salah, K., Keddam, M., Rahmouni, K., Srhiri, A., and
Takenouti, H., Electrochim. Acta, 2004, vol. 49, nos. 17–
18, pp. 2771–2778.
Studies on the synthesis of 3-(N-arylamino)-5-amino-
1Н-1,2,4-triazoles and on optimization of the process
conditions were supported by the Ministry of Education and
Science of the Russian Federation within the framework of
the government assignment for higher schools in the sphere
of scientific activity for the years 2017–2019, project no.
4.3633.2017/4.6.
https://doi.org/10.1016/j.electacta.2004.01.038
9. Moussa, M.N.H., El-Far, A.A., and El-Shafei, A.A.,
Mater. Chem. Phys., 2007, vol. 105, pp. 105–113.
https://doi.org/10.1016/j.matchemphys.2007.04.007
10. Rivera-Grau, L.M., Casales, M., Regla, I., Ortega-
Toledo, D.M., Ascencio-Gutierrez, J.A., Porcayo-
Calderon, J., and Martinez-Gomez, L., Int. J. Electrochem.
Sci., 2013, vol. 8, pp. 2491–2503.
Electrochemical and electroless corrosion tests were
financially supported by the Science and Engineering
Research Board (SERB, New Delhi, India, grant SB/FT/CS-
101/2014).
11. Wittenbrook, L.S., Smith, G.L., and Timmons, R.J., J.
Org. Chem., 1973, vol. 38, no. 3, pp. 465–471.
https://doi.org/10.1021/jo00943a011
CONFLICT OF INTEREST
12. Mansfeld, F., in Advances in Corrosion Science and
Technology, Boston, MA: Springer, 1976.
The authors declare that they have no conflict of interest.
https://doi.org/10.1007/978-1-4684-8986-6_3
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