Научная статья на тему 'Quantum chemical modeling of adsorption of thiourea derivatives, that used as inhibitors of microbiological corrosion on the iron of St3s grade of steel'

Quantum chemical modeling of adsorption of thiourea derivatives, that used as inhibitors of microbiological corrosion on the iron of St3s grade of steel Текст научной статьи по специальности «Химические науки»

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Ключевые слова
УРЕИДЫ / ОРГАНИЧЕСКИЕ ПРОИЗВОДНЫЕ ДИКАРБОНОВЫХ КИСЛОТ / THIOUREA DERIVATIVES / СКОРОСТЬ КОРРОЗИИ / CORROSION RATE / СУЛЬФАТРЕДУЦИРУЮЩИЕ БАКТЕРИИ / SULFATE-REDUCING BACTERIA / СЕРОВОДОРОДНАЯ КОРРОЗИЯ / HYDROGEN SULFIDE CORROSION / ХИМИЧЕСКАЯ АДСОРБЦИЯ / CHEMICAL ADSORPTION / СТАЛЬ СТ3 / ST3 STEEL / ЖЕЛЕЗО / IRON / ПАРЦИАЛЬНЫЕ ЭФФЕКТИВНЫЕ ЗАРЯДЫ / PARTIAL EFFECTIVE CHARGES / ГЛОБАЛЬНАЯ ЭЛЕКТРОФИЛЬНОСТЬ МОЛЕКУЛЫ / GLOBAL ELECTROPHILICITY OF THE MOLECULE / КОМПЛЕКСНЫЕ СОЕДИНЕНИЯ / COMPLEX SUBSTANCES / UREIDS

Аннотация научной статьи по химическим наукам, автор научной работы — Sikachina Andrei

In the published work, the process of adsorption of organic derivatives of thiourea and dicarboxylic acids (thiourea class) modeled with semi-empirical ZINDO / 1, on iron (97% in steel St3, Poland) is presented. The structures of “thiourea” for the study were chosen so that the sequential complication of the molecular structure could be traced. Such an approach, as will be shown below, reflects with high accuracy the process of protection against corrosion with bacterial content by chemisorption of an organic compound on the metal surface with the formation of a complex compound. In the course of the study, the following compositions were obtained and analyzed: the compositions of the complexes obtained, global and local electro-filter values, a graph showing the dependence of the local electrophilicity of an arbitrary heteroatom taken by the author. The graph shows the equations of the obtained lines.

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ПРОДУКТЫ КОНДЕНСАЦИИ ТИОМОЧЕВИНЫ И ЯНТАРНОЙ И КРОТОНОВОЙ КИСЛОТ (УРЕИДЫ) КАК ИНГИБИТОРЫ МИКРОБИОЛОГИЧЕСКОЙ КОРРОЗИИ СТАЛИ: МОДЕЛИРОВАНИЕ АДСОРБЦИИ

В публикуемой работе представлен смоделированный посредством полуэмпирического ZINDO/1 процесс адсорбции органических производных тиомочевины и дикарбоновых кислот (класса уреидов), на железе (имеющегося в стали Ст3 в количестве 97%). Структуры уреидов для исследования были выбраны так, чтобы прослеживалось последовательное усложнение молекулярной структуры. Такой подход, как будет показано далее, с высокой точностью отражает процесс защиты от коррозии с бактериальным контентом путем хемосорбции органического соединения на поверхности металла с образованием комплексного соединения. В процессе исследования были получены и проанализированы: составы полученных комплексов, глобальных и локальных величин электрофильности, график, отображающий зависимость локальной электрофильности произвольно взятого автором гетероатома. На графике показаны уравнения полученных прямых.

Текст научной работы на тему «Quantum chemical modeling of adsorption of thiourea derivatives, that used as inhibitors of microbiological corrosion on the iron of St3s grade of steel»

ХИМИЧЕСКИЕ НА УКИ / CHEMICAL SCIENCES

UDC 627.257:621.3.035.221.727:621.315.617.1

QUANTUM CHEMICAL MODELING OF ADSORPTION OF THIOUREA DERIVATIVES, THAT USED AS INHIBITORS OF MICROBIOLOGICAL CORROSION

ON THE IRON OF ST3S GRADE OF STEEL

ПРОДУКТЫ КОНДЕНСАЦИИ ТИОМОЧЕВИНЫ И ЯНТАРНОЙ И КРОТОНОВОЙ КИСЛОТ (УРЕИДЫ) КАК ИНГИБИТОРЫ МИКРОБИОЛОГИЧЕСКОЙ КОРРОЗИИ

СТАЛИ: МОДЕЛИРОВАНИЕ АДСОРБЦИИ

©Sikachina A.

SPIN-code: 8133-3363, ORCID: 0000-0002-0695-1750 Immanuel Kant Baltic Federal University Kaliningrad, Russia, [email protected] ©Сикачина А. А.

SPIN-код: 8133-3363, ORCID: 0000-0002-0695-1750 Балтийский федеральный университет им. И. Канта г. Калининград, Россия, [email protected]

Abstract. In the published work, the process of adsorption of organic derivatives of thiourea and dicarboxylic acids (thiourea class) modeled with semi-empirical ZINDO / 1, on iron (97% in steel St3, Poland) is presented. The structures of "thiourea" for the study were chosen so that the sequential complication of the molecular structure could be traced. Such an approach, as will be shown below, reflects with high accuracy the process of protection against corrosion with bacterial content by chemisorption of an organic compound on the metal surface with the formation of a complex compound. In the course of the study, the following compositions were obtained and analyzed: the compositions of the complexes obtained, global and local electro-filter values, a graph showing the dependence of the local electrophilicity of an arbitrary heteroatom taken by the author. The graph shows the equations of the obtained lines.

Аннотация. В публикуемой работе представлен смоделированный посредством полуэмпирического ZINDO/1 процесс адсорбции органических производных тиомочевины и дикарбоновых кислот (класса уреидов), на железе (имеющегося в стали Ст3 в количестве 97%). Структуры уреидов для исследования были выбраны так, чтобы прослеживалось последовательное усложнение молекулярной структуры. Такой подход, как будет показано далее, с высокой точностью отражает процесс защиты от коррозии с бактериальным контентом путем хемосорбции органического соединения на поверхности металла с образованием комплексного соединения. В процессе исследования были получены и проанализированы: составы полученных комплексов, глобальных и локальных величин электрофильности, график, отображающий зависимость локальной электрофильности произвольно взятого автором гетероатома. На графике показаны уравнения полученных прямых.

Keywords: thiourea derivatives, ureids, corrosion rate, sulfate-reducing bacteria, hydrogen sulfide corrosion, chemical adsorption, St3 steel, iron, partial effective charges, global electrophilicity of the molecule, complex substances.

Ключевые слова: уреиды, органические производные дикарбоновых кислот, скорость коррозии, сульфатредуцирующие бактерии, сероводородная коррозия, химическая адсорбция, сталь Ст3, железо, парциальные эффективные заряды, глобальная электрофильность молекулы, комплексные соединения.

The economic and environmental damage from corrosion in industry is associated with high metal intensity of equipment and the presence of highly aggressive media [1-4]. An effective method of protection in such environments is the use of corrosion inhibitors [5-6], the synthesis of new forms of which is continuously expanding, [7], as the requirements of industrial companies are tightened to high efficiency at low concentrations (100 ... 200 mg / L). This research is a contribution to the development of the search for organic compounds that can act as corrosion inhibitors, which is currently being conducted not so much through screening, but also by involving more and more aspects of the numerical experiment, the most recent of which is the quantum chemical modeling of the adsorption of an organic compound on a metal [7-11]. The author attempts to achieve this by searching for a relationship between the protective effect of corrosion and the values of the quantum chemical descriptors of adsorption complexes resulting from the donor-acceptor interaction of the organic compound with iron atoms, which provides a predictive basis for preliminary studies of the organic compound as a corrosion inhibitor.

A large amount of data on the inhibition of corrosion with the help of the derivatives of thiourea (U Y) is not present. In a number of works it is proposed to use thiourea and its derivatives as inhibitors of acid and hydrogen sulfide corrosion of steel [12-13]. In aqueous media, thiourea at a concentration of 0.03 ... 5.0 mmol / L slows down the cathodic reaction (at lower thiourea concentrations) and anode (at higher thiourea concentrations) on carbon steel. However, it was shown in [14] that the introduction of thiourea into acidic chloride media can cause an increase in the flux of hydrogen diffusion into carbon steel, which can lead to hydrogen brittleness of the metal.

Effective corrosion inhibitors added to gasolines and distillate fuels are mixed salts of carboxylic acids. Corrosion slows the formation of rust by adding an oil-soluble inhibitor, the lithium salt of alkyl- or alkenylsuccinic acid, to lubricating oils. As magnesium-soluble inhibitors, magnesium salts of organic acids have also been studied [15].

Methods

A variety of microbiological corrosion system

In the article investigated the heterogeneous thermodynamic system of closed type "St3S/breeding ground of Postgate "B" class + Desulfovibrio desulfuricans сells". Samples of steel were parameters 20*50* 1 mm. Samples of steel were taken from one batch, which guaranteed them the same chemical composition [16].

Using organic inhibitors and their method of application in the corrosion system

3 representatives of the "thiourea" class were selected. 3 representatives act as inhibitors of hydrogen sulfide corrosion, added at a concentration of 1, 2, 10 mmol / L contained in a closed system (this is a tube with a volume of 0.9 L) Liquid sterile de-oxygenated medium Postgate "B" (Table 1).

The protective effect against corrosion

The protective effect against microbiological corrosion (Z%) was published in [17-18], calculated by gravimetric method, mentioned in many works, including [19-22], therefore the inhibitory effect of these compounds has been proven. According to [22], the above structure was a structural series of molecules.

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Table 1.

THE STRUCTURES OF THE MOLECULES OF THE INVESTIGATED INHIBITORS AND THE NUMBERING OF THE ASSUMED ADSORPTION CENTERS

Abbreviation of inhibitor

Structural formulas with numbered (according to the author, not according to IUPAC) assumed _adsorption centers_

Preferred IUPAC name of inhibitor

Molecular weight

U1

2-sulfanylidene-

2,3,4,7-tetrahydro-1H-1,3-diazepine-4,7-dione

157.1

U2

2-sulfanylidene-1,3-diazepane-4,7-dione

236.3

U3

4-(acetyloxy)-3-[(4,7-dioxo-4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl)sulfanyl]phenyl acetate

213.2

The technology of quantum chemical calculations

The quantum chemical experiment was carried out with HyperChem 8.0.7, using the built-in visualization tools.

The scientific novelty of the study is the application of a more informative approximation of the donor-acceptor interaction of the U Y with iron atoms aFe0 + U Y = Fea ^ [U Y] (the support and the base were the Lewis representations, from which it follows that the U Y is the Lewis base, and the iron atom is Lewis acid). The calculation was performed using HyperChem 8.0.7. Software, empirically, the limit was set by the number of iron atoms: number a, when out of (a + b) given by HyperChem-user iron atoms carrying zero charge number b. The plane of neutral iron atoms specified by HyperChem-user was 1.2 A (angstroms) away from the U Y plane with the expectation that the program produced fewer iterations, which provides the necessary accuracy. Then it was assumed that the U Y donor possibilities are exhausted. Equation electrophilic aFe0 + U Y = [U Y]^Fea reaction, where iron atoms are acceptors, which are charged negatively. Finding the values of quantum chemical descriptors held level theory MM+, OPLS / PM3 / ZINDO / 1 [14, 16, 23]. OPLS most accurately reflects non-covalent interactions, while the two-dimensional structure given by the researcher, consisting of a molecule of the inhibitor and iron atoms lying in one plane, turns into a three-dimensional one. Mesomeric effect was taken into account, which is manifested in different parts of the investigated U Y. In the following controlled descriptors of electronic structure: charges on heteroatoms (by Mulliken) will be calculated as Eq, i. e. charges on the same arrangement of atoms will be summarized as a result of a high degree of symmetry of the test running, the energy frontier orbitals, the resulting composition [U Y] ^ Fea, where the U Y acts as a ligand. Based on these characteristics will be calculated from the data file, out: the charge density on the iron (1 atom of Fe), global and local electrophilicity, consider the complex structure. Along the length of "Fe-heteroatom" bond taken into account within the 2.50 A.

Software was computed: charges on heteroatoms through the analysis of Mulliken populations, the energy of boundary orbitals (the author did not set the goal of mapping and reviewing software-calculated content). Of these, global and local electrophilicity values of both "thiourea" and thiourea complexes based on "thiourea" (ю, ю) were derived. Local electrophilicity, calculated due to the symmetry of compounds, with preliminary summation of charges on symmetrically located heteroatoms, but also you will see the values of local electrophilicities in terms of 1 heteroatom, on the basis of which comparisons will be made (Figure 1-3).

Results and discussion

Properties of the general molecular structure

The simplest formulas for "thiourea" and obtained ironcomplexes, and shortened encodings and global electrophilicity too are shown in Table 2.

Table 2.

DESCRIPTORS OF AN INTEGRAL MOLECULE

Code of Formulas Global Code of Formulas Global

inhibitor of ironcomplexes electro- inhibitor of inhibitor electrophilicity

ironcomplexes philicity

Fea MU1] Fe<^C4H402N2S 3.450 U1 C4H4O2N2S 1.863

Fea MU2] Fes ^C4H602N2S 1.959 U2 C4H6O2N2S 1.767

Fefl MU3] Fe14 ^CwH^Oe^S 1.857 U3 C^^^S 1.972

The donor properties of heteroatoms are reflected by the global and local electrophilicity values. From the presented Figures, it is obvious that the magnitude of the global electrophilicity (ro) of the U Y under consideration falls in the series U3-U1-U2. There is a drop in the number of electrons that can be attached to the metal surface, the number of multiple bonds decreases, which explains why the number of adsorbed iron atoms decreases with decreasing number of conjugated bonds. ro decreases in the series U1-U2-U3.

The protective effect, manifested by iron complexes of "thiourea", decreases in the series Fe14 ^ [U3], Fe8 ^ [U2], Fe9 ^ [U1]. On the one hand, the high protective effect of Fe14 ^ [U3] is due to the large number of iron atoms reacted with the large molecule U3. On the other hand, in the series of iron complexes Fe14 ^ [U3], Fe8 ^ [U2], Fe9 ^ [U1], the Fukui function (FF) falls, characterizing the change in global electrophilicity (this is U3FFro = 1.587, U2FFro = 0.192, U1FFro = -0.115, respectively). This illustrates the strength of donor-acceptor "Fe-heteroatom", since the largest value of FFro shows the highest strength of donor-acceptor bonds.

Values of local electrophilicity of heteroatoms of molecular structure

The adsorption process directly depends on the local electrophilicity. The Figures 1 -3 reflects the local electrophilicity values due to the total charges on the symmetrically arranged atoms of the thiourea fragment (EUAqE) and the hydroquinone fragment (EHAqE), where E is any heteroatom.

The change in the magnitude of local electrophilicity during complexation (angles with the abscissa axis)

It is obvious from the Figures 1-3 that the more the values of the local electrophilicity of different heteroatoms differ from each other (in the iron complex or in the initial substance) and the smaller the change in these values during the chemisorption, the larger is the Z% value.

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Основной

Основной ^

Основной X—Основной

Atoms

UAqN

хиДдО

UAqS

Figure 1. Values of local electrophilicity of heteroatoms in C4H4O2N2S (from the left side) and in Fe9 ^ C4H4O2N2S (from the right side) and its changes in the chemisorption process

Основной

Основной

Основной Ж

Основной Ж

Atoms

A UAqN

UДqО

Ж UAqS

Figure 2. Values of local electrophilicity of heteroatoms in C4H602N2S (from the left side) and in Fe8 ^ C4H602N2S (from the right side) and its changes in the chemisorption process

Основной —

X Основной

Основной

Ж -Основной

A UAqN

Основной

X Основной Основной в

Atoms

UДqО

Ж -Основной

Ж UAqS

Figure 3. Values of local electrophilicity of heteroatoms in C14H1406N2S (from the left side) and in Fe14 ^ C14H1406N2S (from the right side) and its changes in the chemisorption process

Values of local electrophilicity

Two phenomena contribute to the value of the index of local electrophilicity (Figures 1-3): the thiourea structure and the depth of the electron density transition along the "Fe-heteroatom" bonds, which is determined by the value of the Fukui function, which all the more strongly the thiourea heteroatom performs a donor activity on a specific iron atom, increasing the charge on the heteroatom. Thus, in U1, the distribution of local electrophilicity values is юUДqs — юUДqo — юuЛqN.

The volume of sulfur can take electrons from the metal thickness, promoting its ionization (short Fe-S bonds), so the maximum protective effect at the highest concentration does not exceed 43%.

Therefore, the main adsorption centers are oxygen and nitrogen atoms. This can be explained by the presence of mesomeric effect in the whole chain (by the benzene principle), and a large electron density flows from the whole molecule to oxygen atoms. Further, from the oxygen atoms of the ketogroups, the electron density is doped to the metal (the value of FF is the highest, therefore, toE^qo is high).

In the structurally similar to U2 (and also in U3 including the substituent bonded through the sulfur bridge) the following: юUДqN — юUДqO — юUДqS. The electrophilicity of sulfur is lowered, and the protective effect reaches 54%. In U2, unlike U1, 5C-6C bond is single, and the mesomeric effect can manifest only on a part of the molecule. Then the critical value in the process of chemisorption has a nitrogen atom as less electronegative, therefore the highest value of юUДqN is high, since the value of the Fukui function is large in connection with the strong donation of the electron density to the iron atom. In U3, the decrease in the magnitude of the local electrophilicity of the sulfur atom is expressed most sharply: the sulfur atom donates its electron density and facilitates the outflow of the latter from the thiourea fragment to the hydroquinone fragment. The same applies to the atoms 7O and 8O. The values of the local electrophilicity indices are extremely low = -0.574 and = 0.305) — their participation in the aFe + U Y = Fea ^ [U Y]

reaction is indirect through the mutual influence of atoms in the molecule.

There is also a tendency towards enolization, while a less electronegative nitrogen atom better densifies the electron density on the metal orbital, and on the oxygen atom there can be some positive charge that contributes to the electro-sorption on the metal. This inclination is higher on U2 than on U1.

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Analyzing the values of local electrophilicity, in the molecule U3, most likely, the electron density flows from the substituent (hydroquinone fragment) to the main chain (thiourea), since the calculated is strongly reduced. This can be the result of two simultaneous reactions: the

first is aFe0 + U Y = Fea ^ [U Y], and the second is the non-covalent interaction of the substituent with the iron atoms.

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Figure 4. Graphical dependence of the type "EUAqE — Z%" and the corresponding equations of the

computer-generated trend lines

Graphic dependence of the protective effect against corrosion on the heteroatom parameter

The relationship between the local electrophilicity of the sulfur atom (roUAqS or shorter than ro (S)) and Z% is as follows

If the graphical dependence were parallel, it would mean that there is no chemisorption component in the effect of inhibiting microbiological corrosion.

According to Figure 4 (with linear trend lines generated by the computer, with the applied equations of such), the protective effect of corrosion grows the more, the lower roUAqS. This phenomenon manifests itself starting with Z% = 20 at the lowest taken concentration and ending at Z% = 31, etc. Electrophilicity, while this should decrease (which proves the participation of this atom in the process of chemisorption). The smaller the concentration of the inhibitor, the stronger the local electrophilicity of the sulfur atom will decrease, which is the key to manifesting a high protective effect. In case of occurrence of Z% = 31%, 41%, 51% roUAqS is a zero value. This obviously occurs because the sulfur atom is practically not involved in connection with iron atoms at the indicated Z% values. After Z% = 31%, 41%, 51%, the further increment of Z% can be only when the nucleophilicity of the sulfur atom increases, i. e. the decisive role in the mission of inhibitor protection begins to have electrosorption.

The structures of adsorption complexes, on which the inhibitory properties depend

The structure of the donor and acceptor complexes (by the example of donor and acceptor bonds) is shown in Tables 3-5.

Table 3.

LENGTHS OF DONOR AND ACCEPTOR BONDS IN FE9^C4H402N2S_

The charge of a particular iron atom Name of bonds with heteroatom quantum chemically calculated length relationships, А

-0.350 Fe-зО Fe-iN 2.43 2.31

-0.235 Fe-зО 2.14

-0.235 Fe-5C Fe-бС 2.49 2.41

-0.364 Fe-4O 2.38

-0.517 Fe-iN Fe-2N 2.25 2.39

-0.271 Fe-40 2.34

-0.364 Fe-40 Fe-2N 2.38 2.45

-0.334 Fe-S Fe-2N 2.50 2.50

-0.154 Fe-S 2.50

Table 4.

LENGTHS OF DONOR AND ACCEPTOR BONDS IN FE8 ^C4H602N2S

The charge of a particular iron atom Name of bonds with heteroatom quantum chemically calculated length relationships, А

Fe-S 2.50

-0.427 Fe-iN 2.47

Fe-зО 2.38

-0.244 Fe-iN 2.50

-0.234 Fe-зО 2.20

-0.258 Fe-5C 2.40

Fe-бС 2.42

-0.465 Fe-2N 2.34

Fe-зО 2.38

-0.319 Fe-40 2.16

Fe-2N 2.50

-0.469 Fe-iN 2.25

Fe-бС 2.40

-0.390 Fe-2N 2.40

Fe-S 2.48

LENGTHS OF DONOR AND ACCEPTOR BONDS IN FE14 ^C,4H1406N2S

Table 5.

The charge of a particular iron atom

Name of bonds with

quantum chemically calculated

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heteroatom length relationships, А

-0.347 Fe-40 2.17

Fe-2N 2.29

-0.495 Fe-2N 2.41

Fe-6C 2.41

-0.436 Fe-6C 2.50

Fe-40 2.15

Fe-30 2.28

-0.393 Fe-6C 2.41

Fe-5C 2.50

-0.359 Fe-30 2.29

-0.594 Fe-2N 2.39

Fe-юО 2.36

Fe-юО 2.45

-0.534 Fe-30 2.50

Fe-jN 2.47

-0.282 Fe-юО Fe-!2CH3 2.50 2.46

-0.416 Fe-!2CH3 Fe-80 2.46 2.26

-0.691 Fe-„CH3 2.45

-0.451 Fe-70 2.26

Fe-„CH3 2.42

-0.436 Fe-6C 2.50

Fe-40 2.15

-0.504 Fe-90 2.21

-0.651 Fe-А 2.25

-0.691 Fe-А 2.46

In the structure of Fe9 ^ C4H4O2N2S it is obvious that the iron atom has a coordination number in the range I ... II (Table 3). The coordination numbers seem to correlate with charges: when the charge on an iron atom is greater than -0.334, there are the highest coordination numbers. The bonds of the iron atom with the amide-fragment, formed with both 8O and iN are the shortest. Dentativity for oxygen atoms of keto groups is V. Dentativity for nitrogen atom is V, for sulfur atom and carbon is II. Therefore, the main adsorption center is a nitrogen atom and an oxygen atom of keto groups.

In the structure of Fe8 ^ C4H^O2N2S it is obvious that the iron atom has a coordination number in the range I ... III (Table 4). The coordination numbers seem to correlate with charges: when charged on an iron atom greater than -0.469, there are the highest coordination numbers. The bonds of iron atoms with oxygen of the keto groups of the thiourea ring are the shortest (2.16 ... 2.20 A). Dentativity in oxygen atoms of keto groups is IV. Dentativity at the nitrogen atom is equal to VI, for the atom of sulfur is II and for the atom of carbon is III. Therefore, the main adsorption center is a nitrogen atom.

In the structure of Fe14 ^ C14H14O6N2S it is obvious that the iron atom has a coordination number in the range I ... III (Table 5). The coordination numbers seem to correlate with charges: when charged with an iron atom larger than -0.416, there are the highest coordination numbers. The bonds of the iron atoms with the oxygen of the keto groups of the thiourea ring (2.15 ... 2.29 A) and oxygen atoms of the acetyl fragment (2.21 ... 2.26 A) are the shortest. The dentativity in oxygen atoms of the keto groups of the thiourea ring is equal to V, for oxygen atoms of the keto groups of

acetyl are IV, for phenolic oxygen atoms is II (due to the electron density donation to the benzene ring, therefore, the carbon atom of the benzene ring (7or 8 O-C bond) has value of dentation V). The dentativity with respect to the nitrogen atom is IV. The dentativity by methyl groups is IV, the dentativity by 5C and 6C is V. The electron density of the sulfur atom, unlike that of sulfur atoms U1 and U2, is extremely strongly delocalized on [(4,7-dioxo-4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl) sulfanyl] and 4-(acetyloxy)-3- ... phenyl rings, so this atom does not directly participate in the formation of Fe-S bonds. The presence of a large number of adsorption centers causes a very high Z%.

Atoms 5C and 6C in the U1 ... U3 have dentativity II ... V (the highest is in U2 and U3, where the bond is 5C-6C), since the hydrogen atoms at them have acidic properties (the effect of carboxyl groups, together with the electronegativity of the nitrogen atoms in the thiourea molecule, which are condensation products of thiourea and succinic acid (U2 and U3)) and, under the action of bases, are capable of producing an anionic center. The basic (that is nucleophilic agent) from the "Postgate B + sulfatereduction bacteria environment" system will be able to eliminate the H-atoms.

Conclusion

Application of article approach, such as lack of hydration molecules, the use of pure iron atoms cluster instead of steel, neglect of participation in the adsorption of molecular hydrogen sulphide and its ions, semi-empirical methods of calculation sand modeling obviously do not impose the print on the accuracy and predictive ability of the author improved cluster modeling theory. This enhancement allows you to get more information about protection of inhibitors of metal than the traditional and generally accepted theory. Including the correlation method used in [17] and earlier (with respect to sulfonamides) in [18].

The improved method of quantum chemical modeling provides a much more comprehensive set of data that can serve as an effective tool for forecasting. Because ironcomplexes is not seen as superficial, and as an independent organic compound (or rather, the adduct) with well-defined chemical composition, is similar to n-complexes may be calculated as the actual value of the electronic tags last structure and function of Fukui. This represents a great promise, because currently the selection of microbial corrosion inhibitors increasingly performed quantum-chemical methods of prediction [24], not a screening method [25-26].

Perhaps from such data (most likely from the graphical dependencies of the protective effect against corrosion or the rate of corrosion), in the near future a detailed card file will be created that covers all classes of organic compounds, which will leave a trial and error method in the past, because in the synthesis of a new inhibitor, the corrosion inhibitory action changes (often for the better) with a very slight "structural adjustment" of the molecule of the already known inhibitor.

There is no doubt that a significant role in shaping improvements quantum chemical modeling belongs to the tremendous development of the power of new versions of quantum chemical programs, as well as the full development of visual imaging software. As soon as supercomputers are increasingly becoming an essential attribute of any area of the economy, all of the above approach will be less needed along with an increase in the level of quantum-chemical theory.

Competing interests

The author declares that they have no competing interests.

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CnucoK литературы:

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2. Dasami P. M., Parameswari K., Chitra S. Inhibition of Mild Steel Corrosion in 1M H2SO4 Medium by Benzimidazole Mannich bases // Oriental Journal of Chemistry. 2015. V. з1. №1. P. 185-191. DOI: 10.13005/ojc/310120.

3. Karthik D., Tamilvendan D., Prabhu G. V. Study on the inhibition of mild steel corrosion by i^-bis^morpholin^-yl-phenyl-methy^-thiourea in hydrochloric acid medium // Journal of Saudi Chemical Society. 2014. V. 18. №6. P. 8з5-844. DOI: 10.1016/j.jscs.2011.10.009.

4. Gupta M., Mishra J., Pitre K. S. Corrosion and Inhibition Effects of Mild Steel in Hydrochloric Acid Solutions Containing Organophosphonic Acid // International Journal of Corrosion. 201з. ID 582982. 5 p. DOI: 10.1155/201з/582982.

5. Sathiq M. A., Nasser A. J. A., Sirajudeen P. M. Adsorption and Corrosion Inhibition Effect of N-(l-Morpholinobenzyl)urea onMild Steel in Acidic Medium // E-Journal of Chemistry. 2011. V. 8. №2. P. 621-628. DOI: 10.1155/2011/892548.

6. Scendo M., Uznanska J. Inhibition Effect of 1-Butyl-4-Methylpyridinium Tetrafluoroborate on the Corrosion of Copper in Phosphate Solutions // International Journal of Corrosion. 2011. ID 761418. 12 p. DOI: 10.1155/2011/761418.

7. Raphael V. P., Shanmughan Sh. K., Kakkassery J. Th. Monitoring the Interaction of Two Heterocyclic Compounds on Carbon Steel by Electrochemical Polarization, Noise, and Quantum Chemical Studies // International Journal of Corrosion. 2016. ID 4204532. 10 p. DOI: 10.1155/2016/4204532.

8. Khaled K. F., El-Maghraby A.. Experimental, Monte Carlo and molecular dynamics simulations to investigate corrosion inhibition of mild steel in hydrochloric acid solutions // Arabian Journal of Chemistry. 2014. V. 7. №3. P. 319-326.

9. Khodaei-Tehrani M., Niazi A. Quantum chemical studies on the corrosion inhibition of some hector bases on mild steel in acidic medium // Oriental Journal of Chemistry. 2015. V. 31. №1. DOI: 10.13005/ojc/310150.

10. Guo L., Ren X., Zhou Y., Xu Sh., Gong Yu., Zhang Sh. Theoretical evaluation of the corrosion inhibition performance of 1,3-thiazole and its amino derivatives // Arabian Journal of Chemistry. 2017. V. 10. №1. P. 121-130. DOI: 10.1016/j.arabjc.2015.01.005.

11. Karthikaiselvi R., Subhashini S. Study of adsorption properties and inhibition of mild steel corrosion in hydrochloric acid media by water soluble composite poly (vinyl alcohol-o-methoxy aniline) // Journal of the Association of Arab Universities for Basic and Applied Sciences. 2014. V. 16. P. 74-82. DOI: 10.1016/j.jaubas.2013.06.002.

12. Cardoso S. P., Gomes J. A. C. P., Borges L. E. P., Hollauer E. Predictive QSPR analysis of corrosion inhibitors for super 13% Cr steel in hydrochloric acid // Brazilian Journal of Chemical Engineering. 2007. V. 24. №4. P. 547-559. DOI: 10.1590/S0104-66322007000400008.

13. Prabhu G. V., Karthik D., Tamilvendan D. Study on the inhibition of mild steel corrosion by 1,3-bis-(morpholin-4-yl-phenyl-methyl)-thiourea in hydrochloric acid medium // Journal of Saudi Chemical Society. 2014. V. 18. №6. P. 835-844. DOI: 10.1016/j.jscs.2011.10.009.

14. Geethamani P., Kasthuri P. K. Adsorption and corrosion inhibition of mild steel in acidic media by expired pharmaceutical drug // Cogent Chemistry. 2015. V. 1. 1091558. DOI: 10.1080/23312009.2015.1091558.

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16. Nasser A. J. A., Sathiq M. A. Comparative study of ^-[(4-methoxyphenyl) (morpholin-4-yl)methyl]acetamide (MMPA) and ^-[morpholin-4-yl(phenyl)methyl]acetamide (MPA) as corrosion inhibitors for mild steel in sulfuric acid solution // Arabian Journal of Chemistry. 2017. V. 10. №1. P. 261-273. DOI: 10.1016/j.arabjc.2012.07.032.

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21. Awe F. E., Idris S. O., Abdulwahab M., Oguzie E. E. (2015). Theoretical and experimental inhibitive properties of mild steel in HCl by ethanolic extract of Boscia senegalensis // Cogent Chemistry. 2015 V. 1). 1112676.

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23. Laarej K., Bouachrine M., Radi S., Kertit S., Hammouti B. Quantum Chemical Studies on the Inhibiting Effect of Bipyrazoles on Steel Corrosion in HCl // E-Journal of Chemistry. 2017. V. 7. №2. P. 419-424. DOI: 10.1155/2010/273206.

24. Shukla H. S., Haldar N., Udaybhanu G. Binary Mixtures of Nonyl Phenol with Alkyl Substituted Anilines as Corrosion Inhibitors for Mild Steel in Acidic Medium // E-Journal of Chemistry. 2012. V. 9. №1. P. 149-160. DOI: 10.1155/2012/278496.

25. Bouhrira K., Ouahiba F., Zerouali D., Hammouti B., Zertoubi M., Benchat N. The Inhibitive Effect of 2-Phenyl-3-nitroso-imidazo [1, 2-a]pyridine on the Corrosion of Steel in 0.5 M HCl Acid Solution // E-Journal of Chemistry. 2010. V. 7. №1. P. 35-42. DOI: 10.1155/2010/525606.

26. Nwankwo H. U., Ateba C. N., Olasunkanmi L. O., Adekunle A. S., Isabirye D. A., Onwudiwe D. C., Ebenso E. E. Synthesis, Characterization, Antimicrobial Studies and Corrosion Inhibition Potential of 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane: Experimental and Quantum Chemical Studies // Materials. 2016. V. 9. №2. DOI: 10.3390/ma9020107.

Работа поступила Принята к публикации

в редакцию 19.06.2017 г. 22.06.2017 г.

Cite as (APA):

Sikachina, A. (2017). Quantum chemical modeling of adsorption of thiourea derivatives, that used as inhibitors of microbiological corrosion on the iron of St3s grade of steel. Bulletin of Science and Practice, (7), 8-21

Ссылка для цитирования:

Sikachina A. Quantum chemical modeling of adsorption of thiourea derivatives, that used as inhibitors of microbiological corrosion on the iron of St3s grade of steel // Бюллетень науки и практики. Электрон. журн. 2017. №7 (20). С. 8-21. Режим доступа: http://www.bulletennauki.com/sikachina-a-a (дата обращения 15.07.2017).

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