KINETICS OF COHERENT-SYNCHRONIZED PEROXIDASE OXIDATION OF ETHYL ALCOHOL TO ACETALDEHYDE ON HETEROGENIZED BIOMIMETIC CATALYSTS Текст научной статьи по специальности «Химические науки»

ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)

UDC 546.215.547.313.577.1

KINETICS OF COHERENT-SYNCHRONIZED PEROXIDASE OXIDATION OF ETHYL ALCOHOL TO ACETALDEHYDE ON HETEROGENIZED BIOMIMETIC CATALYSTS

U.V.Mammadova1, I.T.Nagieva2, L.M.Gasanova\ T.M.Nagiev12

M.Nagiev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan

2Baku State University

gasanova.48@mail.ru ulduz_nasirova@mail.ru

Received 07.04.2022 Accepted 18.05.2022

The peroxidase activity of the synthesized heterogeneous biomimetic catalysts, PPFe3+OH/Al2O3, TPhPFe3+OH/Al2O3 and per-FTPhPFe3+OH/Al2O3 in the reaction of ethyl alcohol oxidation to acetalde-hyde with hydrogen peroxide has been studied, which showed high catalase activity and unique resistance to the action of highly active intermediate reaction products. As a result of studying the kinetic regularities of the selective biomimetic oxidation of ethyl alcohol with hydrogen peroxide, a coherent-synchronized nature of the reaction was established, consisting of two: 1) catalase and 2) peroxidase reactions. The kinetics of coherent-synchronized peroxidase oxidation of ethyl alcohol to acetaldehyde on het-erogenized biomimetic catalysts, PPFe3+OH/A^O3, TPhPFe3+OH/Al2O3 and per-FTPhPFe3+OH/Al2O3 has been studied. Based on the determinant equation, which makes it possible to qualitatively and quantitatively evaluate the coherent nature of synchronously occurring reactions and the reaction coherence ratio, a kinetic model of the process has been compiled. On the basis of the compiled kinetic model, the effective rate constants of the catalase and peroxidase reactions were derived, respectively. The derived kinetic model of the process is characterized by a high adequate description of the experimental data.

Keywords: ethyl alcohol, hydrogen peroxide, biomimetic, coherent-synchronized reactions, determinant, peroxidase reaction.

doi.org/ 10.32737/0005-2531-2022-3-12-20 Introduction

In recent years, extensive research has been carried out in the field of highly selective oxidation processes through the use of high quality catalysts. Such catalysts are heterogeneous biomimetic catalysts, with the participation of which various processes of oxidative transformation are selectively carried out [1, 2]. The selectivity of the processes is also ensured by the use of hydrogen peroxide as an oxidizer, which in its qualities satisfies the requirements of the "green chemistry" concept and is called the "green oxidizer". The combination of the use of immobilized biomimetic catalysts with highly selective processes in the presence of hydrogen peroxide is very effective and promising in the direction of "green chemistry".

Heterogenized biomimetic catalysts simulating the main functions of monooxygenase enzymes, in particular, cytochrome P-450, have

been synthesized and studied [3-5]. It is known that biomimetic catalysts, which are mimetic analogues of hemin-containing enzymes, are H+-dependent redox systems [6, 7]. Metallopor-phyrin biomimetic catalysts containing inorganic oxides as a matrix, for example, Al2O3, have acid-base centers that play an important role in the mechanism of reaction products formation [8].

As was shown in [9, 10], the use of mimetic catalysis methods for the CH bonds activation in alkanes and alkenes followed by their subsequent monooxygenation allowed us to develop high-selective effective epoxidation and hydroxylation catalysts. The most attractive aspect of these biomimetic catalysts is their ability to accommodate under harsh conditions under which enzymes simply cannot exist. It has been shown that the stability of biomimetic catalysts under heating and the action of oxidizers is largely determined by the reactivity of the protoporphyrin ring.

The possibilities of biomimetic catalysis that we demonstrated for the example of mimetic modeling of monooxygenase enzymes [1, 8], led us to think that these biomimetic systems could be used to perform the peroxidase reaction, which is no less important in fundamental and practical terms of peroxidase reaction. Eth-anol, which is known to be a classical peroxidase substrate, was chosen as a model compound [11, 12].

Experimental part

The synthesis of active centers, iron (III) protoporphyrin, iron (III) tetraphenylporphyrin, and iron (III) perfluorotetraphenylporphyrin (PPFe3+, TPhPFe3+, and per-FTPhPFe3+) biomimetic catalysts, is a multistage process described in [13, 14]. Hemin from BDH with a 8.64% iron content is used to model the active centers of protoporphyrin Fe . As a solid matrix for active centers immobilization, activated or neutral alumina from Aldrich (standard) with spherical particles 1.5 mm in diameter and a surface area of at least 500 m /g was used. The active centers of biomimetic catalysts (hemin, TPhPFe3+, and per-FTPhPFe3+)

are deposited on the surface of neutral or activated A12O3 following the procedures developed by us [8]. The hemin-containing peroxidase biomimetic catalyst was prepared as described in [15]. The PPFe3+OH/AhO3 product contained 1.8 mg of hematin per 1 g of the carrier. The biomimetic catalyst TPhPFe3+OH/Al2O3

was synthesized by

3+

adsorption of TPhPFe3+OH from its solution in benzene on alumina; the adsorbate concentration was 0.76 mg/g. The immobilization of per-FTPhPFe3+OH on AhO3 (1.58 mg/g) was carried out from its solution in dimethylformamide by impregnating alumina. An aqueous solution of hydrogen peroxide was used as an oxidizer. Hydrogen peroxide of kh.ch. grade (chemically pure) was cleaned from possible impurities, in particular from stabilizers, by vacuum distillation. Ethanol of kh. ch. grade was another starting material.

The synthesized catalysts were subjected to liquid-phase testing for their catalase activity in a static system. The results showed that the catalase

activity of the synthetic biomimetic catalysts was high. Note that TPhPFe3+OH/Al2O3 and per-FTPhPFe3+OH/Al2O3 exhibited high stability toward heating and the action of the oxidizer and intermediates. The perfluorinated mimetic catalyst was in addition tested under the action of high oxidizer (H2O2) concentrations. This catalyst exhibited a stable high catalase activity in a 30% aqueous solution of H2O2 for a long time and showed a unique stability toward the action of highly active intermediate oxidation products.

The gas-phase peroxidase reaction with the participation of hydrogen peroxide was carried out in a flow-through quartz reactor with a reac-

3 3

tion zone volume of 3 cm (d=1.8 cm ); the design of the reactor made it possible to introduce H2O2 into the reaction zone in an undecomposed form [8]. The reaction products were analyzed by gas-liquid chromatography on a column (length=100 cm, d=0.3 cm) filled with Porapack Q as an adsorbent. Column temperature 1200C, carrier gas (helium) pressure 0.4 kgf/cm2.

The kinetic regularities of the selective oxidation of C2H5OH (peroxidase reaction) were studied over the temperature range 120-240°C at atmospheric pressure and volume rates of supplying ethanol and hydrogen peroxide of 0.30-0.92 and 1.92-4.80 ml/h, respectively. The C2H5OH:H2O2 molar ratio was 1:2.

Results and discuss

The dependences of the reaction products yields: acetaldehyde (CH3CHO) and molecular oxygen (O2) in the selective oxidation of ethyl alcohol in the presence of biomimetic catalysts with hydrogen peroxide on the contact time are shown in Fig. 1. At short contact times (up to t = 2.3 s), the yield of acetaldehyde (the product of the peroxidase reaction) increased significantly, and the catalase activity (O2 yield) decreased on all three catalysts. Peroxidase activity decreased, while catalase activity, on the contrary, increased markedly with increasing t. This shows that the kinetic curves of the catalase and peroxidase reactions are synchronized, which undoubtedly indicates the interaction of these two reactions and their coherent nature. The kinetic curves of the catalase reaction show

that H2O2 is almost completely decomposed to O2 at low values of t. Then the observed yield of acetaldehyde during the oxidation of C2H5OH with hydrogen peroxide is insignificant. Fig. 2 shows experimental data showing

the consumption of hydrogen peroxide in each of the coherent-synchronized reactions of C2H5OH oxidation and H2O2 decomposition depending on the contact time.

wt.%

o

X

o

5

100 -T

90

80 -■ 5 70

60 4 3 50 -■ 40 30 -■ 2 20 -■ 10 -f 0

6

4

T 90 10 -

-- 75 9 -1

-- 60 7 -

-- 45 1 1 7 -

-- 30 O 7 ". 7

-- 15 7 ": 1 --

■+ 0 7 --

0 1,2 1,65 2,4 3,2

4

t,

Fig. 1. Contact time x dependences of the yields of the products of selective oxidation of C2H5OH [(1-3) CH3CHO and (4-6) O2] at

180°C and C

=20wt.% on (1,4)

TPhPFe3+OH/Al2O3, (2,5) PPFe3+OH/Al2O3, and (3,6) per-FTPhPFe3+0H/Al203.

The consumption of hydrogen peroxide in each of the synchronized reactions of C2H5OH oxidation and H2O2 decomposition is shown in Fig. 2 depending on the contact time. We see that the total consumption of H2O2 in both reactions is equal to its initial amount. This allows us to conclude that the total yield of reaction products corresponds to a constant consumption of H2O2 (actor) regardless of the reaction conditions, that is, we have the following equality:

fHo = fHo + fH,o, = const OX

where f 0 is the initial amount of H2O2, f 1 and f 2 are the amounts of H2O2 consumed in the catalase and peroxidase reactions, respectively.

Due to the condition (1) of the coherence of chemical interference resulting from the in-

0

1

2

3

4 t,

Fig. 2. H202 consumption in primary, catalase (curve 1) and secondary, peroxidase (curve 2) reactions of ethyl alcohol oxidation on per-FTPhPFe3+0H/Al203 under the conditions: t = 180°C, CH0 = 20 wt.%, C2H5OH:H202= 1:2.

teraction of two synchronous reactions, the rate of the catalase reaction (decomposition of H2O2) decreases as the rate of the other (peroxidase) reaction, synchronized with the first one, increases, and vice versa. Such dependences indicate that both reactions (catalase and peroxidase) not only proceed synchronously, but also coherently interact with each other [16].

It is known [16, 17] that catalase, mono-oxygenase, and peroxidase reactions in the systems under consideration proceed through a common intermediate, a hydrogen peroxide fragment activated and bound to a biomimetic catalyst. This highly active intermediate causes a bifurcation in the reaction medium, which causes the observed chemical interference, that is, the mutual intensification and weakening of the reactions.

The kinetic conditions of chemical interference manifestations are quantitatively estimated by the determinant equation [17]:

1

2^2

D = ' + fHA 1 fcHOH )" (2)

where fCHOH is the amount of ethyl

alcohol consumed and v is the stoichiometric coefficient of hydrogen peroxide (actor). In our reaction v=1.

The experimental determinant value calculated by this equation for the optimum conditions of the biomimetic oxidation of ethyl alcohol to acetaldehyde on TPhPFe3+OH/Al2O3 (180°C, [H2O2] = 20 wt. % in water, molar ratio C2H5OH:H2O2 =1:2, t = 1.6-3.2 s) is D = 0.300.50. According to the scale of the determinants of chemical interference [17], this value is in the region of chemical conjugation, when the

primary reaction of the decomposition of H2O2 induces the secondary reaction of the oxidation of C2H5OH (the peroxidase reaction).

It follows that two synchronous reactions are in a state of interaction due to the fulfillment of the conditions of coherence (f =

const) and induction (D = 0.30-0.50). They constitute a chemical interference in the form of synchronized and interconnected kinetic curves of catalase and peroxidase reactions. These two coherent-synchronized reactions catalyzed by heterogeneous biomimetic catalysts are described by the following mechanism:

Scheme 1

H2O2

H2O

ImtOH

ImtOOH

CH3CHO + H2O C2H5OH

H2O + O2 H2O2

Here ImtOH stands the biomimetic catalyst (PPFe3+OH/Al2O3, TPhPFe3+OH/Al2O3 or per-FTPhPFe3+OH/Al2O3) and ImtOOH is the intermediate, (1) - catalase (primary) and (2) - peroxidase (secondary) reactions. Both reactions presented in this scheme proceed through a common intermediate ImtOOH, which transfers the inducing action of the primary (catalase) reaction to the secondary (peroxidase) reaction.

Considered biomimetic catalysts contain aluminum oxide as a heterogeneous acid-base carrier. Aluminum oxide has terminal and bridging Broensted acid and basic centers [18], which play an important role in the catalytic transformations of ethanol. It was noted above that the redox-active sites

(PPFe3+OH,

TPhPFe3+OH h per-FTPhPFe3+OH) have a structure stabilized by the coordination of the main transfer center (Al-O:) to the functional groups of the substituted ironporphyrin catalysts, especially due to the coordination in the axial position of the central iron ion.

The mechanism of the peroxidase action of the biomimetic catalysts proposed above can be represented in the form of elementary events corresponding to modern ideas about the mechanism of functioning of their biomimetic analogues in the framework of the theory of bond redistribution [19-21]. These elementary reactions are shown in Scheme 2.

In the above diagram of the peroxidase reaction, the acidic and basic sites are, respectively, AH and B, and the arrows show the direction of electron movement. According to the multicenter mechanism of the catalase reaction given above (Scheme 2), at the first stage, the heterolytic interaction of H2O2 with the redox center of the biomimetic catalyst with synchronous participation of acid-base transfer centers with the formation of ImtOOH. The ligand

'OOH in the [ImtOO№C2H5OH] complex is an electron acceptor, while C2H5OH is an electron donor.

HO + ImtOH

■ о, \ . о

Scheme 2 Catalase reaction

HO + ImtOOH-

Î

->H2O + O2 + ImtOH

b

ii

4-

О

1 - acid and 2 - basic centers of Al2O3 carrier

P e r o x i d a s e r e a c t i o n

ImtOH + HO + CH3CHO

. Their interaction regenerates the active sites of biomimetic catalysts with the formation of reaction products, CH3CHO and H2O. In the peroxidase reaction diagram above, an unusual feature is the direction of one of the arrows, showing

how the electrons move along the bond redistribution chain (BRC). This arrow begins with the hydroxyl hydrogen C2H5OH and points to the oxygen atom associated with iron. This section of the electron movement along the BRC,

*

which is unusual at first glance, was explained in [19].

The above Scheme 2 allows us to trace the sequence of electron transfer events along the BRC. The transfer of an electron from the C2H5OH molecule to the main center of the carrier B is accompanied by the breaking of the CH bond and the transition of the electron to the carbon atom. Further, the splitting of another OH bond in C2H5OH and the formation of a C=O bond makes it possible to transfer this electron

to a hydrogen atom, followed by a hydride ion shift. The entire sequence of electron transfer acts in the BRC does not require large energy expenditures. According to this mechanism, two hydrogen atoms simultaneously pass from the C2H5OH molecule, but in different forms: one in the form of a proton, and the other in the form of a hydride ion.

The reaction system controlled by the mechanism proposed above is two-substrate and includes two reactions:

H2O2 + ImtOH —^ ImtOOH + H2O k2'H2°2 > H2O + O2 + ImtOH (I)

fast

CH3CH2OH + ImtOOH —CH3CHO + H2O + ImtOH (II)

where k1t k2, and k3 are the rate constants of corresponding reactions.

The general equation for the secondary reaction of acetaldehyde formation can be obtained by summing the elementary event of ImtOOH formation (I) and reaction (II):

C2H5OH+H2O2=CH3CHO+H2O (III)

Note that for kinetic modeling of the oxidation of C2H5OH to acetaldehyde with hydrogen peroxide, it is necessary to make the following substantiated assumption: the stage of formation of the ImtOOH complex is fast, the stage of formation of CH3CHO is slow; that is, the last reaction is the rate-determining step. Unlike classical kinetic modeling [22], it is of great interest to conduct a kinetic study of the peroxidase reaction of ethanol oxidation from the standpoint of the theory of coherent-synchronized reactions [17], taking into account

chemical interference described by the determinant equation (2). Due to the fact that in the reaction under study the per-FTPhPFe3+OH/Al2O3 bi-omimetic catalyst showed the highest activity and high resistance to the action of an oxidizing agent, the results of experiments obtained in the presence of this catalyst were used to carry out the kinetic modeling of this process (Table 1).

Table 1. The experimental data of ethyl alcohol peroxidase oxidation by hydrogen peroxide on bioimitator per-FTPhPFe3+OH/Al2O3

No T, K T, s Conv. of C2H5OH, % VH2O2 ml/h VC2H5OH ml/h [H2O2] % P RT

i 433 i .73 61.0 0.028

2 453 i .65 64.0 3.48 0.67 20 0.027

3 473 1.60 70.3 0.026

Peroxidase monooxidation of ethanol on the per-FTPhPFe3+OH/Al2O3 bioimitator proceeded according to the following scheme:

H2O2 + ImtOH-

ki

ImtOOH + H2O

k2, H202

actor

ImtOH + H2O + O2 primary reaction

k3, C2H5OH

acceptor

CH3CHO + ImtOH + H2O secondary reaction

where the primary reaction is the decomposition of hydrogen peroxide (catalase reaction), and the secondary reaction is the oxidation of etha-nol to acetaldehyde (peroxidase reaction).

As can be seen from the scheme, hydrogen peroxide is consumed by all reactions occurring in the system at rates:

V2c2 = ki[H2O2][ImtOH] ^h2O2 = k2[H2O2][ImtOOH] Wo = k 3 [C 2H 5 OH] [Im tOOH]

(3)

(4)

(5)

Since v = 1 (the stoichiometric coefficient of the actor - hydrogen peroxide, the overall reaction is 1), then the rate of consumption of H2O2 can be taken as the rate of monooxida-tion of ethanol, then

r3,H2O2 = rc2H5OH = k3[C2H5OH][ImtOOH] (6)

where r is the rate of intermediate formation

1,H2O2

in catalase reaction; r2H O is the rate of H2O2

consumption in catalase reaction; r3HO is the

rate of H2O2 consumption in peroxidase reaction of ethanol oxidation; r is the rate of etha-

nol consumption in peroxidase reaction.

Substituting the expressions for the rates of catalase and peroxidase reactions into the determinant equation (2), we have:

D = v

r X1

r2,H2O2 r3,HO2

r

(7)

3,C2H5OH y

The rate of hydrogen peroxide consumption in the peroxidase reaction can be expressed in terms of the difference in the rates of hydrogen peroxide consumption in the intermediate formation reaction and the catalase reaction:

r3,H2O2 = ri,H2O2 — r2,H2O2

Then equation (7) takes the form:

D = v

r2,H2O2 + ri,H2O2 r2,H2O2

Y1 (

=v

(8)

V *3,C2H5OH y

Because v = 1, then:

D =

V r3,C2H5OH y

or

D

r

3,C2H5OH r

(9)

The rate of hydrogen peroxide consumption in the reaction of the intermediate formation can be expressed through the determinant in the following form:

1,H,O,

_ r3,C2H5OH

= D Wherefrom,

r3,C2H5OH = ri,H2O2

• D

(10)

(11)

According to the above scheme, we have that the rate of consumption of ethanol

,HsOH) in the peroxidase reaction depends on

the current concentration of ethanol, the concentration of the intermediate, and the rate constants of the reactions occurring in the system:

13,C,HOH

k • k

k—3 [ImtOH][C2H5OH] k^

(12),

where k1 is the rate constant of intermediate formation reaction; k2 is the rate constant of catalase reaction; k3 is the rate constant of peroxidase reaction; C[C2H5OH] is the current concentration of ethyl alcohol.

Comparing the left parts of equations (11) and (12) we will have the following expression: k • k

[ImtOH][C2H5OH] = W • D (13) k2 2 2

If we take the set of constant values of this expression (the rate constants of the reactions occurring in the system and the concentration of the intermediate) as the effective reaction rate constant, we will have:

k • k

[ImtOH] = k3ff,

k

(14)

where keff is the effective rate constant of the

reaction of ethyl alcohol oxidation by hydrogen peroxide, or kp^ is the effective rate constant of the peroxidase reaction.

r

1,H2O2

r

1.H,O

22

r

3.CHOH

2^5

Expressing (13) via (14), we obtain:

k3 -

keff -

1,H,O,

D

[C2H5OH]

or kper -

• D

[C2H5OH]

kcat k eff -

[C2H5OH]

D[H 2 O 2 ]2

(15)

(16)

Thus, for the coherent-synchronized reactions (catalase and peroxidase) occurring in the system, the effective rate constants k cefaft and

kpffr were found.

As can be seen from equations (15) and (16), the effective rate constants of the catalase

and peroxidase reactions depend, in addition to other reaction parameters, on the value of the determinant factor D, which confirms the coherent-synchronized nature of these reactions. Using the equations (15) and (16) we derived above, we will find the numerical values of the effective rate constants of the catalase and peroxidase reactions, as well as the activation energy of the peroxidase reaction using the Arrhe-nius equation (table 2).

Note that the value of the effective activation energy of the peroxidase reaction of the oxidation of ethyl alcohol with hydrogen peroxide to acetaldehyde is within the limits characteristic of enzymatic reactions (Table 2).

Table 2. The kinetic parameters values of the reaction of ethyl alcohol peroxidase oxidation by hydrogen peroxide on

T,K r1,H2O2 x10-5 mole/sm3s r2,H2O2 x10-5 mole/sm3s cons. -5 rC2H5OH x10 mole/sm3s D kea1 xio3, s-1 kper, s-1 Eper Eeff kJ/mole

433 0.178 0.121 0.057 0.32 0.628 0.904 24.78

453 0.179 0.118 0.061 0.34 0.550 1.087

473 0.178 0.112 0.066 0.37 0.416 1.464

r

22

Conclusion

As a result of our kinetic investigation of the process of peroxidase biomimetic monooxi-dation of ethyl alcohol by hydrogen peroxide to acetaldehyde on the heterogenized biomimetic catalyst, per- FTPhPFe3+OH/Al2O3, we come to the following conclusion: the kinetic model compiled on the basis of the determinant equation and the coherence ratio of coherent-synchronized catalase and peroxidase reactions differs by high adequate description of experimental data.

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sennix zhelezoprotoporphirinovix katalizatorov.

HETEROGENLO§DiRlLMi§ BiOMiMETiK KATALiZATORLAR UZORINDO ETiL SPiRTiNiN ASETALDEHiDO KOHERENT-SiNXRONLA§DIRILMI§ PEROKSiDAZ OKSiDLO^MOSiNiN

KINETiKASI

U.V.Mammadova, I.T.Nagiyeva, L.M.Hasanova, T.M.Nagiyev

Yuksak katalaz aktivliyina va aktiv araliq reaksiya birla§malarina qar§i unikal davamliliga malik sintez edilmi§ heterogen biomimetik PPFe3+OH/Al2O3, TPhPFe3+OH/Al2O3 va per-FTPhPFe3+OH/Al2O3 katalizatorlarin etil spirtinin hidrogen pero-ksidla asetaldehida oksidla§masi reaksiyasinda peroksidaz aktivliklari tadqiq edilmi§dir. Etil spirtinin hidrogen peroksidla biomimetik selektiv oksidla§masinin kinetik qanunauygunluqlarinin oyranilmasi naticasinda reaksiyanin iki: 1) katalaz va 2) peroksidaz reaksiyalardan ibarat koherent-sinxronla§dmlmi§ xarakteri muayyan edilmi§dir. Heterogenla§dirilmi§ biomimetik PPFe3+OH/Al2O3, TPhPFe3+OH/Al2O3 va per-FTPhPFe3+OH/Al2O3 katalizatorlar uzarinda etil spirtinin asetaldehida koherent-sinxronla§dinlmi§ peroksidaz oksidla§masinin kinetikasi tadqiq edilmi§dir. Sinxron ba§ veran reaksiyalann koherentliyini keyfiy-yat va kamiyyatca qiymatlandirilan determinant tanliyi va reaksiyanin koherentlik nisbati asasinda prosesin kinetik modeli tartib edilmi§dir. Tartib edilmi§ kinetik model asasinda katalaz va peroksidaz reaksiyalarin effektiv surat sabitlari ugun muvafiq kinetik ifadalar gixanlmi§dir. Prosesin kinetik modeli eksperimental naticalarin yuksak adekvat tasviri ila farqlanir.

Agar sozlar: etil spirti, hidrogen peroksid, biomimetik, koherent-sinxronla§dirilmi§ reaksiyalar, determinant, peroksidaz reaksiyasi.

КИНЕТИКА КОГЕРЕНТНО-СИНХРОНИЗИРОВАННОГО ПЕРОКСИДАЗНОГО ОКИСЛЕНИЯ ЭТИЛОВОГО СПИРТА В АЦЕТАЛЬДЕГИД НА ГЕТЕРОГЕНИЗИРОВАННЫХ БИОМИМЕТИЧЕСКИХ КАТАЛИЗАТОРАХ

У.В.Мамедова, И.Т.Нагиева, Л.М.Гасанова, Т.М.Нагиев

Исследована пероксидазная активность синтезированных гетерогенных биомиметических катализаторов -PPFe3+OH/Al2O3, TPhPFe3+OH/Al2O3 и per-FTPhPFe3+OH/Al2O3 в реакции окисления этилового спирта в ацетальдегид пероксидом водорода, которые проявили высокую каталазную активность и уникальную устойчивость к действию высокоактивных промежуточных продуктов реакции. В результате изучения кинетических закономерностей селективного биомиметического окисления этилового спирта пероксидом водорода установлен когерентно-синхронизированный характер протекания реакции, состоящей из двух: 1) каталазной и 2) пероксидазной реакций. Изучена кинетика когерентно-синхронизированного пероксидазного окисления этилового спирта в ацетальдегид на гетерогенизированных биомиметических катализаторах - PPFe3+OH/Al2O3, TPhPFe3+OH/Al2O3 и per-FTPhPFe3OH/Al2O3. На основе уравнения детерминанты, которая позволяет качественно и количественно оценить когерентный характер синхронно протекающих реакций и соотношения когерентности реакций составлена кинетическая модель процесса. На основе составленной кинетической модели выведены эффективные константы скоростей каталазной и пероксидазной реакций, соответственно. Выведенная кинетическая модель процесса отличается высоким адекватным описанием экспериментальных данных.

Ключевые слова: этиловый спирт, пероксид водорода, биомиметик, когерентно-синхронизированные реакции, детерминанта, пероксидазная реакция.