МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ
АКАДЕМИЧЕСКИХ НАУК
175
ADSORPTION PROPERTIES OF A MULTI-FUNCTIONAL
IMIDAZOLINE-BASED INHIBITOR
Y.Sh. Usmonova,
Sh.F. Ruziev,
Т.B. Тuraev,
Kh.I. Каdirov
Tashkent Institute of Chemical Technology, Tashkent
https://doi.org/10.5281/zenodo.15526166
Abstract.
During the research, the optimal conditions for the synthesis of 2-
hexadecyl-2-imidozoline C
20
H
40
N
2
, 2-octadecyl-2-imidozoline C
21
H
40
N
2
, and 2-
octadecyl-2-imidozoline C
21
H
38
N
2
from the three-acid fraction (TAF) obtained by
adsorption of wood chips and extraction in isopropyl alcohol were determined.
98% ethylenediamine was used for the synthesis. TAF is a mixture of palmitic,
oleic, and linoleic acids, present in a ratio of 30.3+22.7+42.3% by mass,
respectively.
Keywords:
imidazolines, trihydric acid fraction, fatty acids, corrosion
inhibitor, diamides, oil production, environmental sustainability
Imidazolines and compositions based on them exhibit a high protective effect
not only against carbon dioxide and hydrogen sulfide corrosion, but also in acidic
environments [1, 2]. Based on this, surfactants and imidazoline compositions with
the addition of a solvent were tested in 5, 10, 15 wt.% aqueous solutions of
hydrochloric and sulfamic acids for 24 hours at room temperature. The
concentration of inhibiting compositions ranged from 0.03 to 1.00% by mass.
According to GOST R 9.905-2007 and technical regulations of oil and gas
production enterprises, the maximum permissible corrosion rate of steel St.3
under these conditions should be 0.2 g/ (m
2
∙h) [3].
One of the important methods for the synthesis of alkylimidozolines is the
reaction of ethylene diamine or polyethylene polyamines with fatty acids:
or based on their reactions with esters
:
The process is carried out in two stages. Step 1: Formation of acidic amidoamines
from fatty acids with ethylene diamine:
R – COOH + H
2
NCH
2
CH
2
NH
2
N
N – H
R
+ 2H
2
O
R – COOR
1
+ H
2
NCH
2
CH
2
NH
2
N
N – H
R
+ R
1
OH + H
2
O
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Step 2: Amidoamino acid heterocyclization to form alkylimidozoline derivatives:
Diamides are formed as secondary products of the process:
Carboxylic acid diamides are poorly soluble in water and organic solvents,
decompose into monoamides under reaction conditions, have low surface
activity, and their presence in the finished product negatively affects its quality.
The separation of diamide from the finished product is carried out by the
rectification method, which requires additional costs. To achieve economic
efficiency in industry, pure fatty acids are not used, but their mixtures. However,
the use of a mixture of fatty acids causes technological problems in determining
optimal reaction conditions, leading to a decrease in imidazoline yield and an
increase in by-products. Experiments show that the proportions of the resulting
alkylimidozoline and diamide are related to the electrophilicity of the carbonyl
carbon of the acylation agent, i.e., the chain length of the carbonic acid radical.
During the research, the optimal conditions for the synthesis of 2-hexadecyl-
2-imidozoline C
20
H
40
N
2
, 2-octadecyl-2-imidozoline C
21
H
40
N
2
, and 2-octadecyl-2-
imidozoline C
21
H
38
N
2
from three acid fractions (TAF) adsorbed on wood chips and
extracted with isopropyl alcohol were determined. 98% ethylenediamine was
used for the synthesis.TAF is a mixture of palmitic, oleic, and linoleic acids,
containing 30.3+22.7+42.3% by mass.
Three different reactions were carried out to determine the optimal
conditions for the heterocyclization reaction. Methodology of the experiment: a
three-gorney flask was equipped with a thermometer, a Wurtz nozzle with a Libix
refrigerator, and a mechanical stirrer. Thermal treatment of the reaction mass
was carried out using an electric heater. 100 g of TAF and 100 g of
ethylenediamine were placed in the reactor, heated to 40°C, and a stirrer was
switched on during the melting of TAF. During intensive mixing and gradual
temperature increase in the cooler at 130 °C, condensation of water vapor was
observed, and condensate accumulated in the collector. When the temperature
was raised above 200 °C, the excess ethylenediamine was also removed, and at a
temperature above 250 °C, the water of the heterocyclization reaction was
removed. Heat treatment was carried out at a temperature of 270 °C for 1 hour.
Then the process is carried out in a vacuum of 180 mm Hg. After 1 hour,
heterocyclization was completed, and the remaining water was separated. The
synthesis was completed, and the resulting product was analyzed using IR
spectrum and gas-liquid chromatography methods.
R – COOH + H
2
NCH
2
CH
2
NH
2
R - CONHCH
2
CH
2
NH
2
+ H
2
O
R - CONHCH
2
CH
2
NH
2
N
N – H
R
+ H
2
O
R - CONHCH
2
CH
2
NH
2
+ R - COOH
R - CONHCH
2
CH
2
NHCO - R + H
2
O
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Subsequent studies were associated with a decrease in the amount of acid
diamides in the finished product, as well as experiments were conducted with a
change in the carboxylic acid:amine ratio and an increase in the amount of
ethylenediamine. For this, 50 g of TAF, 100 g of ethylenediamine (TAF:EDA÷1:4)
were added to the reaction flask and the sequence of experiment 1 was continued.
When analyzing the IR spectrum of the finished product obtained in these
proportions, it can be seen that the intense lines characteristic of diamides are
relatively reduced. Calculations of the chromatographic peaks show that the
molar
ratios
of
alkylimidozolines
(hexadecyl-,
octadecyl-
and
octadecenylimidozolines) to diamides decreased by 1.5-1.8 times compared to
experiment 1: diamides: alkylimidozolines 1: 4.8 mol and or 9.32: 90.68 wt. %.
will be in proportions. At the same time, it can be concluded that even the
introduction of 4 times more ethylenediamine into the reaction medium did not
lead to a decrease in the selectivity of the diamide formation reaction.
Figure 1. Chromatogram of
the product obtained in the
ratio of TAF: EDA 1:4:
6-,7- and 9-alkylimidozolines;
15, 16, and 18 are products of
acylation of ethylene diamine
with palmitic, oleic, and
linoleic acids, respectively.
During the research, the mechanism of chemical changes was studied, and
pure fatty acid - palmitic acid was used as an acylating reagent in the experiments.
It has been established that with increasing the temperature of the reaction
mixture, the fatty acid reacts not only in a mono-, but also in a dimeric state and
forms three-molecular complexes in the acid-amino acid system due to mutual
hydrogen bonds according to the following scheme:
Trimolecular complexes form stable structural diamides (2), diammonium
salts (3) and acid amide monohydrates (4) with ion-exchange activity at 130 °C:
(2)
C
15
H
31
- C
O ···· H
O - H
NH - CH
2
CH
2
- HN
H - O
H ····
C - C
15
H
31
O
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
C – C
15
H
31
O
+ 2H
2
O
(1)
C
15
H
31
- C
O····H - O
O - H····
C – C
15
H
31
+ H
2
N - CH
2
CH
2
- NH
2
O
C
15
H
31
- C
O ···· H
O - H
NH - CH
2
CH
2
- HN
H - O
H ····
C – C
15
H
31
O
МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ
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(3)
(4)
A large amount of ethylenediamine provides a strongly alkaline environment
for the reaction, and under such conditions, proton substitution occurs in
trimolecular complexes and salts with a binary structure are formed:
(5)
At the same time, with an increase in temperature to 130 °C, internal
diamidation of salts or ammonium hydrates also occurs:
(6)
This reaction, which proceeds with the conversion of the binary complex to
diamidoamine, is of great importance in the formation of alkylimidozolines. In the
second stage of the reaction, thermal treatment results in the formation of 2-
hexadecyl-2-imidozoline from aminoethylenamide of hexadecyl acid:
(7)
Aminoethylenamide of hexadecyl acid, in turn, can also be formed as a result
of amidation from a tri-molecular acid-amino acid complex:
(8)
Aminoethylenamide of hexadecyl acid forms diamides in the secondary
direction:
(9)
C
15
H
31
- C
O ···· H
O - H
NH - CH
2
CH
2
- HN
H - O
H ····
C - C
15
H
31
O
C
15
H
31
- C
O
O - NH
3
- CH
2
CH
2
- NH
3
- O
C – C
15
H
31
O
–
–
+
+
C
15
H
31
- C
O ···· H
O - H
NH - CH
2
CH
2
- HN
H - O
H ····
C - C
15
H
31
O
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
2
· HO
C – C
15
H
31
O
+ H
2
O
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
2
·
HO
C – C
15
H
31
O
+
NH - CH
2
CH
2
- NH
2
·
HO
H
2
N - CH
2
CH
2
- NH
2
2 C
15
H
31
- C
O - NH
3
- CH
2
CH
2
- NH
2
–
+
O
+ H
2
O
2 C
15
H
31
- C
OH
O
·
H
2
N - CH
2
CH
2
- NH
2
2 C
15
H
31
- C
NH - CH
2
CH
2
- NH
2
O
+
H
2
O
2 C
15
H
31
- C
NH - CH
2
CH
2
- NH
2
O
N
N – H
C
15
H
31
+ 2H
2
O
2
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
2
·
HO
C – C
15
H
31
O
+ H
2
O
2 C
15
H
31
- C
NH - CH
2
CH
2
- NH
2
O
+ H
2
NCH
2
CH
2
NH
2
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
2
·
HO
C – C
15
H
31
O
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
C – C
15
H
31
O
+ H
2
O
МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ
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Considering the ease of the formation of the triple acid-amino acid complex
compared to the reactions of the initial carbonic acid and ethylene diamine, as
well as the ease of the intracomplex reaction compared to the intermolecular
interaction reactions, it is clear that diamide can be formed at any molar amount
of ethylene diamine (even if taken 20 times more). Furthermore, along with the
heterocyclization of amidoamino acid, the heterocyclization of diamides was
observed, and the formation of 2-hexadecyl-1- (2-hexadeclami- noethyl) -2-
imidozoline also influenced the selectivity of the reaction. Under experimental
conditions, peaks close to the molecular weight of 2-hexadecyl-1- (2-hexadecyl-
aminoethyl) -2-imidozoline diamides are observed:
Thus, during the synthesis of alkylimidozolines, to reduce the amount of the
secondary product - diamide, it is necessary to prevent the formation of the initial
acid dimer, and with it, the triple acid-amino acid complex. To achieve the set goal,
reactions were carried out in the "ethylenediamine - carbonic acid" system during
the research, and the sequence of adding the raw materials to the initial reaction
was studied. At the first stage of heat treatment, ethylene diamine was introduced
into the reactor first, and then carbonic acid was added, which allowed the
reaction to proceed along the path of bimolecular acylation without the initial
stage of ammonium salt formation:
The phased transfer of diamine to carbonic acid limits the formation of the
resulting acylamidoethylenamine according to the following reactions:
After transferring all the carbonic acid to the reaction medium, the control of
the reaction was continued as in experiment 1. In the IR spectrum of the product
obtained as a result of the reaction, the C=N bond vibration lines characteristic of
C
15
H
31
- C
OH
O
N
N – H
C
15
H
31
+ H
2
O
+ H
2
N - CH
2
CH
2
- NH
2
C
15
H
31
- C
NH - CH
2
CH
2
- NH
2
O
C
15
H
31
- C
NH - CH
2
CH
2
- NH
2
O
+ H
2
O
C
15
H
31
- C
NH - CH
2
CH
2
- NH
2
O
C
15
H
31
- C
OH
O
+
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
C – C
15
H
31
O
+ H
2
O
C
15
H
31
- C
NH - CH
2
CH
2
- NH
2
O
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
C – C
15
H
31
O
+ H
2
N - CH
2
CH
2
- NH
2
(10)
C
15
H
31
- C
O
NH - CH
2
CH
2
- NH
C – C
15
H
31
O
N
N – CH
2
CH
2
NH
C
15
H
31
+ H
2
O
C – C
15
H
31
O
МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ
АКАДЕМИЧЕСКИХ НАУК
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the imidozoline heterocycle (1608 cm-1), intense lines characteristic of the C=O
bond (1668 cm-1), and absorption lines characteristic of the deformation
vibrations of the N-H bond (1556 cm-1) were observed.
Figure 2. IR spectrum of the product obtained in the "Carbon Acid -
Ethylenediamine" system.
Chromatographic analyses showed that the total surface area of
alkylimidazoline peaks was 1:28 relative to diamide peaks, at a ratio of
0.48:99.52% by mass. It was found that it was equal to 2-hexadecyl-1- (2-
palmythylaminoethyl) -2-imidazoline. It was noted that the amount of 2-
hexadecyl-2-imidazoline sharply decreased and amounted to 1.52%.
Figure 3. Chromatogram of the
product
obtained
in
the
"Etilenediamine to carbonic
acid" system: 6-, 7- and 9-
alkylimidazolines; 17-, 19- and
20- are products of acylation of
ethylene diamine with palmitic,
oleic,
and
linoleic
acids,
respectively.
Thus, by changing the sequence of raw material transfer in the
ethylenediamine-carboxylic acid system, it was possible to minimize the amount
of diamide formed.
At the initial stage of the research to determine the inhibitor adsorption
process, the corrosion rates of steel samples in various aggressive environments
were studied. The use of mineralized water saturated with dissolved gases such
as hydrochloric and sulfamic acids, as well as carbon dioxide and a mixture of
carbon dioxide and hydrogen sulfide, made it possible to assess the influence of
such factors as the composition of the medium and the pH value on the activity
and adsorption of the developed inhibitory composition. Changing the medium
velocity from a static state to 1 m/s allowed us to assess the influence of the
aggressive medium flow velocity on the adsorption properties of the corrosion
inhibitor. To determine the time required to achieve maximum inhibitor
МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ
АКАДЕМИЧЕСКИХ НАУК
181
adsorption on the metal surface, a time interval of 3 to 24 hours was used.
Figure 4 (A and B) shows the dependence of the corrosion rate of St.3 steel
samples on the experimental time in a mineralized model water-bearing medium
saturated with CO
2
and H
2
S.
А - 0 m/s; В - 1,0 m/s
Figure 4. The corrosion rate of St.3 steel in a medium saturated with
carbon dioxide and a mixture of carbon dioxide and hydrogen sulfide, depending
on the time of the experiment. Experimental conditions: temperature 20±2°C,
0.06% by mass of alkylimidozoline [3] + a composition of a surfactant inhibitor
was added at the following rotation speeds:
When adding the inhibiting compound in concentrations selected based on
previous research results: 0.06% by mass in acidic media and 60 g/m
3
in aqueous
media, at room temperature and rotation speeds from 0 m/s to 1.0 m/s.
According to the obtained data, it was established that the corrosion rate is
higher in an aggressive environment saturated only with carbon dioxide than in
an aqueous environment with the addition of carbon dioxide and hydrogen
sulfide. This can be explained by the formation of corrosion products with
different characteristics and different mechanisms of inhibitor adsorption. While
iron carbonate forms a porous corrosive compound (FeO
FeCO
3
) with acid, which
does not have protective properties, sulfides are denser compounds than
carbonates, therefore in some cases they can act as a protective layer. In addition,
the HS- ions formed in the solution are adsorbed on the metal surface and displace
the adsorbed H
2
O and OH- ions, which ultimately leads to a decrease in the
corrosion rate. Adding a small amount of H
2
S to the CO
2
medium can reduce the
reduction rate of H
2
O and H
2
CO
3
, limiting the corrosion process. In both
environments, the minimum corrosion rate is reached 18 hours after the start of
the experiment.
Determination of the protective effect of the considered inhibitory
composition was carried out based on the values of the corrosion rate measured
in purely aggressive media without the addition of an inhibitor. The results
obtained in a water medium saturated with dissolved gases are presented in
Figure 5 (A and B).
The determination of the protective effectiveness of the considered
inhibitory composition was carried out based on the values of the corrosion rate
in pure aggressive media without the addition of an inhibitor. The results obtained
0,02
0,04
0,06
0,08
0,10
0,12
0,14
0,16
CO
2
CO
2
+H
2
S
τ, соат
5 10
15
A
ко
рр
ози
я
те
злиг
и
,
г
/
м
2
·с
оа
т
0,02
0,04
0,06
0,08
0,10
0,12
0,14
0,16
CO
2
CO
2
+H
2
S
τ, соат
5 10
15
B
ко
рр
ози
я
те
злиг
и
,
г
/
м
2
·с
оа
т
МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ
АКАДЕМИЧЕСКИХ НАУК
182
in a water medium saturated with dissolved gases are presented in Figure 5 (A and
B).
Figure 5 - Dependence of the protective effectiveness of inhibitory
composition No. 3 (0.06% mass.) on the duration of the experiment (at a
temperature of t=20±2°C) in a medium saturated with carbon dioxide and
hydrogen sulfide. Rotational speeds: A = 0 m/s; B - 1.0 m/s
From these graphs, it can be concluded that the protective effect of the
inhibiting composition in the presented media changes over time. The protective
effect indicators are closely related to the corrosion rate values, showing the
highest results after 18 hours.
After the experiment, they decrease insignificantly or do not change, which
indicates the formation of reaction products as a result of competing processes of
adsorption and desorption of the inhibitor, as well as the corrosion process. The
protective effect is higher in a mineralized aqueous medium saturated with both
hydrogen sulfide and carbon dioxide, which is explained by the positive influence
of HS- ions on the inhibitor adsorption process. The adsorption of these anions on
the steel surface facilitates the interaction of positively charged inhibitor
molecules with the metal, resulting in the formation of stronger Fe (H-S-R)
compounds, less detachment from the steel surface, and consequently, more
effective metal protection. The appearance of a dynamic factor initially leads to an
increase in protective effect values, which can be explained by increased diffusion
of inhibitor molecules to the surface. However, with a further increase in the
consumption of the aggressive medium, the protective effect indicators decrease
somewhat, which is explained by the shift of the equilibrium in the processes of
adsorption-desorption of the inhibitor on the steel surface towards desorption.
Moreover, dynamic conditions contribute to the separation of corrosion products
formed during the reaction, which, in turn, can have a positive effect on corrosion
protection.
Foydalanilgan adabiyotlar:
1.
Lopez D.A., Perez T., Simison S.N. The influence of microstructure and
chemical composition of carbon and low alloy steels in CO2 corrosion. A state- of-
the-art appraisal //Materials & Design. – 2003. – Vol. 24. – №. 8. – P. 561-575.
30,0
40,0
50,0
60,0
70,0
80,0
90,0
100
82
90
94
97
53
56
73
66
30,0
40,0
50,0
60,0
70,0
80,0
90,0
100
74
78
87
91
54
56
56
60
Э
, %
B
5 10 15 20
τ
,
соат
5 10 15 20
τ
,
соат
A
МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ
АКАДЕМИЧЕСКИХ НАУК
183
2.
Kadirov Khasan Irgashevich, Turabdjanov Sadritdin Mahamatdinovich.
Synthesis of zincate-oxyethenediphosponic acid and the comparative results
applying as scale inhibitors. Europaische Fachhochschule. European Applied
Sciences. Stuttgart, Germany. ISSN 2195-2183. #6 – 2015. S. 66-69
3.Latypov, O.R. Method of Controlling Electrochemical Parameters of Oil Industry
Processing Liquids / O. R. Latypov, D. E. Bugai, E. V. Boev //Chemical and
Petroleum Engineering. – 2015. – V. 51. – Issue 3. – P. 283 - 285.
