Prognostication of the anticorrosive activity in the series of pentenylarylamines and their industrial introduction

Article abstract of DOI:10.1134/S1070427212080071

Quantum-chemical parameters and regression analysis were used to predict and synthesize a number of compounds with the highest inhibiting activity in the series of pentenylarylamines. For the compounds with the highest inhibiting activity, tri-2,4,6-(1'-methyl-2'-butenyl)aniline and di-2,6-(1'-methyl-2'- butenyl)-4-methylaniline, technical documentation was developed and their inhibiting activity in media as close as possible to real oilfield conditions were performed. On the basis of results of these tests, the given compounds are recommended for pilot tests.

Full text of DOI:10.1134/S1070427212080071

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 8, pp. 1182−1185. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © R.N. Khusnitdinov, E.M. Khamitov, K.R. Khusnitdinov, R.R. Gataullin, S.L. Khursan, A.G. Mustafin, I.B. Abdrakhmanov, 2012,
published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 8, pp. 1243−1246.
PHYSICOCHEMICAL STUDIES
OF SYSTEMS AND PROCESSES
Prognostication of the Anticorrosive Activity in the Series
of Pentenylarylamines and Their Industrial Introduction
R. N. Khusnitdinova, E. M. Khamitova, K. R. Khusnitdinovb, R. R. Gataullinb,
S. L. Khursanb, A. G. Mustafina, and I. B. Abdrakhmanovb
aBashkir State University, Bashkortostan, Russia
e-mail: mag@anrb.ru
bInstitute of Organic Chemistry, Ufa Scientific Center, Russian Academy of Sciences, Bashkortostan, Russia
e-mail: mag@anrb.ru
Received March 6, 2012
Abstract—Quantum-chemical parameters and regression analysis were used to predict and synthesize a number
of compounds with the highest inhibiting activity in the series of pentenylarylamines. For the compounds with the
highest inhibiting activity, tri-2,4,6-(1'-methyl-2'-butenyl)aniline and di-2,6-(1'-methyl-2'-butenyl)-4-methylaniline,
technical documentation was developed and their inhibiting activity in media as close as possible to real oilfield
conditions were performed. On the basis of results of these tests, the given compounds are recommended for pilot
tests.
DOI: 10.1134/S1070427212080071
The correlation between the structure and inhibiting
properties has been extensively studied [1–3]. Of
particular interest in recent years has been use, for this
purpose, of quantum-chemical calculations of molecule
properties [4–6], depending on which a tendency toward
an increase in the inhibition efficiency can be revealed.
However, examples of obtaining optimal structures with
the highest inhibiting activity cannot be found in these
publications.
EXPERIMENTAL
Pentenylarylamines were synthesized by the known
procedures [7]. Anticorrosive studies were performed in
conformity with GOST (State Standard) 9.506–87 [9].
The maximum anticorrosive activity was evaluated by
the degree of protection Z (%) in conformity with GOST
9.506–87, determined by the formula
Vko – Vki
Z = –———– × 100,
Vko
It has been shown that alkenylanilines readily acces-
sible via condensation of anilines with hydrohalogenated
1,4-adducts of piperilene or cyclopentadiene are poten-
tial corrosion inhibitors [7, 8]. However, the dependence
of the anticorrosive activity on structural parameters has
not been studied for compounds of this series.
where Vko and Vki are the metal dissolution rates
in media without and with an inhibitor, respectively
(g m–2 h–1).
As witness samples served steels 20, the amounts
of the compounds being tested were 0.033 M, and
the temperature of the hydrochloric acid solution was
maintained at 25 ± 1°.
The goal of our study was to examine the relationship
between the electronic structure of molecules and their
corrosion inhibiting activity in the series of pentenyl
derivatives of aniline, predict and synthesize optimal
corrosion inhibitors, and introduce compounds with the
highest anticorrosive activity into industrial practice.
The quantum-chemical parameters [energy of higher
occupied molecular orbitals, EHOMO (a.u.); energy of
1182

PROGNOSTICATION OF THE ANTICORROSIVE ACTIVITY
1183
lower unoccupied molecular orbitals, ELUMO (a.u.);
negative charge on the nitrogen atom, Qmin (a.u.);
electrophilicity index W; and dipole moment μ(D)] were
calculated using PC GAMESS 7.15 software [10] in the
B3LYP/6-31G(d, p) approximation [11, 12].
amines, we chose monosubstituted pentenylarylamines
synthesized by the known methods [7]. Table 1 lists the
calculated electronic properties of mono pentenylaryl-
amines and the degrees of corrosion protection, deter-
mined for these compounds.
The calculation results were visualized and
preliminarily processed using ChemCraft 1.5 software
[13].
An analysis of the results we obtained demonstrated
that the strongest correlation dependence is observed
in this set of parameters for the negative charge on
the nitrogen atom. For the whole selection of mono
pentenylarylamines I–IX, the correlation coefficient R2
is 0.54 (Table 2). In a stage-by-stage exclusion of ortho-
substituted pentenylarylamines VI and VIII from the
general selection, the correlation coefficient increases
(R2 = 0.59) and reaches a value of 0.95 upon exclusion
of ortho-substituted pentenylarylamines) and reaches
a value of 0.95 upon exclusion of ortho-substituted
pentenylarylamines II, III, VI, and VIII from the
general selection.
All the structures calculated in this study were
subjected to optimization and are stationary points on the
potential-energy surface (PES), which was confirmed
by solution of a vibrational problem: for minima on
the PES, the diagonalized Hessian matrix contains only
positive terms.
We used hydrochloric acid solutions as corrosive
media. Preliminary corrosion tests demonstrated that the
optimal hydrochloric acid concentration for the chosen
compounds is its 16% solution. At low hydrochloric acid
concentrations (1–12%), we have a gross experimental
error, and at high concentrations (20–22%), the
corrosion system does not react on structural changes
for the simplest aromatic amines.
Analysis of the relationship between the inhibiting
activity of the compounds under study and the effective
charge on the nitrogen atom shows that the larger the
latter (in absolute value), the more pronounced the
anticorrosive properties of a compound. Based on this
To study the anticorrosive properties of pentenylaryl-
Table 1. Quantum-chemical parameters of alkenylarylamines and trisubstituted pentyl- and pentenylarylamines and their
degrees of protection
E, a.u.
Qmax
Qmin
a.u.
Zexp Zcalc
Compd.
Compound
W
μ, D
HOMO LUMO
%
I
N-(1-Methyl-2-butenyl)aniline
–0.1869 0.0124 0.0191 0.330 –0.60
–0.1869 0.0124 0.0191 0.330 –0.600 1.852 71.0 71.7
–0.1850 0.0165 0.0176 0.283 –0.61 1.916 72.1
–0.1852 0.0137 0.0185 0.334 –0.601 1.662 72.9 72.1
1.852 69.4 71.7
II
О-(1-Methyl-2-butenyl)aniline
III
IV
V
N-(1-Methyl-2-butenyl)-3-метилaniline
N-(1-Methyl-2-butenyl)-3-methylaniline
N-(1-Methyl-2-butenyl)-4-methylaniline
О-(1-Methyl-2-butenyl)-4-methylaniline
–
–0.1819 0.0128 0.0184 0.325 –0.6
1.552 73.8
–
–
VI
VII
VIII
IX
Х
–0.1879 0.0069 0.021 0.256 –0.667 1.616 76.1
N-(1-Methyl-2-butenyl)-2,4-dimethylaniline –0.1802 0.0164 0.0171 0.276 –0.61
1.627 78.0 75.2
О-(1-Methyl-2-butenyl)-2,4-dimethylaniline –0.1865 0.0113 0.0145 0.125 –0.676 1.505 84.9
–
п-(1-Methyl-2-butenyl)aniline
2,4,6-Tri(1'-butenyl)aniline
2,4,6-Tri-(3'-butenyl)aniline
–0.1927 0.0075 0.0214 0.352 –0.657 1.576 93.0 91.6
–0.1882 0.0181 0.0194 0.155 –0.666 1.428 94.9 94.7
–0.1877 0.0139 0.0187 0.174 –0.672 1.325 97.75 96.8
XI
XII
2,6-Di-(1'-methyl-2'-butenyl)-4-methylaniline –0.1837 0.0063 0.0207 0.255 –0.678 1.689 97.87 98.9
2,4,6-Tri-(1'-methyl-2'-butenyl)aniline –0.1858 0.0057 0.0212 0.255 –0.678 1.898 98.0 98.9
XIII
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 85 No. 8 2012

1184
KHUSNITDINOV et al.
protection institution “Center for Hygiene and
Epidemiology at the Republic of Bashkortostan”
toxicological tests of these compounds belonging to
third class of hazard according to GOST 12.1.007. We
obtained a sanitary-epidemiological statement from the
department of the Federal Service for Supervision of
Consumer Rights Protection and Human Welfare for the
Republic of Bashkortostan. The reagent was registered
at the Federal agency for technological control and
metrology, Federal State Enterprise “Standardization,
Metrology, and Certification Center of the Republic of
Bashkortostan.”
Preliminary studies of the inhibiting activity of
the reagent in corrosive media as close as possible to
those under real industrial conditions were performed
at the chemical laboratory of the department for
complication control of crude-oil production at
OOO “RN-UfaNIPIneft’.” The inhibiting activity of the
given compounds was studied in a 15% hydrochloric
acid solution at a temperature of 90°C by the standard
procedure with steel 20. The results of these tests are
listed in Table 2.
Table 2. Results of preliminary corrosion tests of compounds
XII and XIII. Experimental conditions: 15% hydrochloric
acid solution as model medium, temperature 90°C, exposure
duration 1 h
Compound
Dosage, wt % Degree of protection, %
XII
0.5
1.0
2.0
3.0
4.0
0.5
0.5
1.0
2.0
3.0
4.0
5.0
96.6
97.3
97.4
98.0
98.4
98.8
97.0
97.6
98.0
98.4
98.8
99.1
XIII
prognosis, we synthesized 2,4,6-tri-(1'-methylbutyl)
The results of preliminary corrosion tests in corrosive
media as close as possible to those under real industrial
conditions demonstrated that compounds XII and XIII,
taken in amounts of 0.5–5.0 wt %, have a 97–99%
degree of protection. According to the results of these
tests, the compounds are recommended for pilot tests.
aniline (X), 2,4,6-tri-(3'-methylbutyl)aniline (XI),
2,6-di-(1'-methyl-2'-butenyl)-4-methylaniline
(XII),
and 2,4,6-tri-(1'-methyl-2'-butenyl)aniline (XIII). Table
2 lists electronic properties and degrees of corrosion
protection under the action of the above compounds.
The full set of compounds can be described with
satisfactory accuracy by the correlation equation Z =
The predicted compounds XII and XIII were
synthesized by the known procedure described in [7],
and their spectral characteristics were presented in the
same report. Compounds X and XI were synthesized for
the first time.
–137.44 – 348.61Qmin
.
Using the regression equation for the negative
charge on the nitrogen atom, we calculated the degrees
of corrosion protection for compounds I–XIII under
study. It can be seen in Table 1 that the experimental
and calculated degrees of corrosion protection for the
compounds synthesized coincide within experimental
error and standard calculation errors.
2,4,6-Tri-(1'-methylbutyl)aniline
(X)
was
synthesized by hydrogenation of compound XIII
on skeleton nickel in an alcoholic solvent [14]; nD20
1.5856. Found (%): С 83.05, Н 12.24, N 4.60. С21Н37N.
Calculated (%): С 83.10, Н 12.29, N 4.61.
Based on the results of our study and on the fact that
all the components used to synthesize compounds with
the highest inhibiting activity (XII, XIII are industrially
manufactured, we decided to organize industrial
manufacture of these compounds and recommended to
perform preliminary corrosion tests in media as close as
possible to the real industrial conditions.
For compounds XII and XIII, we developed
production procedures and technical specifications
(TU) 2458-007-20833127–2009 “Yural-3K corrosion
inhibitor.” We performed at Federal state health-
1
IR spectrum, ν, cm–1: 3420, 3490 (NH2). Н NMR
spectrum (CDCl3), δ, ppm (J, Hz): 0.72–0.97 m (9Н,
3СН3), 1.17–1.28 m (9Н, СН3), 1.45–1.55 m (6Н,
3СН2), 1.64–1.75 m (6Н, 3СН2), 2.72–2.80 (3Н, 3СН),
3.56 br.s (2Н, NH2), 6.77 s (2Н, ArH). 13С NMR
spectrum (CDCl3), δ, ppm: 14.4 (3СН3); 20.7 (3СН3);
21.8 (3СН2); 33.2 (3СН2); 40.0 (3СН); 121.7, 132.0,
137.4, 138.6 (С-arom).
2,4,6-Tri-(3'-methylbutyl)aniline (XI) was syn-
thesized by the Friedel–Crafts alkylation of 4-(1-meth-
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PROGNOSTICATION OF THE ANTICORROSIVE ACTIVITY
1185
ylbutyl)aniline produced by the known method [7]
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1.5815. Found (%): С 83.05, Н 12.24, N 4.60. С21Н37N.
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