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MACROSCOPIC COHERENCE IN SYNCHRONIZED CHEMICAL REACTIONS: THE WAY TO SELF-ORGANIZING CHEMICAL SYSTEMS
T.M.Nagiev
M.Nagiev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan
tnagiev@azeurotel.com Received 11.05.2016
Chemistry is on the brink of establishing self-organizing and self-assembling chemical systems where algorithms allowing a group of chemical reactions to combine in an ensemble to obtain a final product in a single reaction medium with high selectivity in a short time are implemented. The synthesis of a target product in a living organism at the cellular level is carried out practically in no time, and this is possible only in conditions coherently synchronized reactions, that represent the ensemble of the chemical reactions at the cellular level. Unfortunately, these reactions have not been practically implemented to enable the development of similar chemical systems, probably due to the lack of adequate theories explaining the working principles of enzyme ensembles (unlike the working principles of individual enzymes). Developed macroscopic theory of the coherently synchronized chemical reactions has been adequately corroborated by experimental studies. Here we propose an experimentally corroborated model of the coherently synchronized reactions and its mathematical apparatus, consisting of determinant equation and coherent correlation. Thus, self-organization of reaction ensemble can be intensified and weakened simultaneously and, therefore, inducing macroscopic coherence, may be suggested as the basis for the principle by which a number of enzymatic ensembles are organized.
Keywords: coherence synchronized chemical reactions, self-organizing chemical systems.
Introduction
There are many types of interaction between reactions. Conjugated processes are the most demonstrative of the reciprocal influence and interaction of two or more reactions.
Practically all types of possible reaction interactions, of which some may be united in a general idea of chemical reaction interference, are discussed here. The notion of interference includes the mutual intensification or weakening of reactions: for instance, the rate of primary reaction product formation decreases, whereas the rate of a secondary conjugated reaction product formation increases. Currently, the mutual influence of reactions synchronized in time and space will be taken for interfering chemical processes [1-3].
With this approach, conjugated reactions appear to be a particular case of coherent synchronized reactions.
Studies performed in recent decades have allowed the development of the interaction theory for synchronous chemical reactions at two levels - microscopic and macroscopic. Strictly speaking, parallel reactions may also be taken as synchronous reactions; although they simultaneously proceed in the reaction system,
they are characterized by the absence of any interaction between them. However, such synchronous reactions are trivial and of no special interest in chemistry. It is of much more importance when they interact and thereby induce oscillations in the yields of synchronous reaction products.
This microscopic coherence of elementary chemical reactions has been described in detail in [4, 5].
"A property of a chemical system to form oscillations in the time regimes of reactions" is a definition of coherence adopted in chemistry [1, 6, 7].
It should be noted for macroscopic coherence that the properties of the chemical system primarily determine the chemical reactions proceeding in this system. That is why it is necessary to make the following clarification: the oscillations in the yields of synchronous reaction products may cause physical processes accompanying chemical reactions and limiting their rate, for example, transport, the diffusion of reagents to the chemical reaction site (active center).
The statement that the time synchronization of reactions is manifested in the frequency of the reactions, which means that the synchro-
nization of reactions is their coherency, needs to be clarified.
The synchronization of chemical reactions at the macroscopic level indicates only that these reactions proceed simultaneously in a single chemical system; this absolutely does not imply their coherence.
The statement that the "macroscopic coherence level" is characterized by the fact that "the concentrations of active reagents (or intermediates) periodically change over time" [8] should be considered within the context of two zones where the chemical reaction proceeds: the diffusional and the kinetic. In the former case, the oscillations in the yields of reaction products are associated with the diffusion of reagents to the active center. This physical process by definition cannot be in a coherent relation with the chemical process as the process proceeds in the diffusional zone, and the rate of chemical reactions is derived from the diffusion equation, which has nothing to do with the equations of the kinetics of the chemical reactions.
Thus, only synchronous reactions of chemical systems proceeding in the kinetic zone can be considered coherent. Although in the dif-fusional zone there may be oscillations in the yields of reaction products, and this often happens, it has nothing to do with coherence phenomena. A striking example of how oscillations in the diffusional zone are mistaken for macroscopic coherence is the Belousov-Zhabotinsky reaction.
It is a very interesting and complex chemical system where oscillations in the yields of reaction products are in fact observed; nevertheless, the oscillations are caused not by coherence but by the physical process of the transport of reacting particles to the active centers, which is mathematically described by the diffusion equation.
To conclude, synchronous chemical reactions in macroscopic conditions of the diffu-sional proceeding zone have oscillations in the yields of the products, but these oscillations are not related to coherence. The oscillations in the kinetic zone, however, are directly related to their coherence.
I absolutely agree with the author [4] that "coherence introduces... new concepts... to chemistry" and "it is not just a new language of chemistry; it is a new level of thinking, a new level of chemical research technology".
Complex reactions within the context of oscillating reactions at the macroscopic level
As noted above, oscillating reactions at the macroscopic level are observed in two zones: the kinetic and the diffusional.
The diffusional zone of the chemical reaction process induces oscillations in the reaction product yields. This type of oscillating reaction has been extensively studied in the literature [8-10].
Elementary chemical reactions that make up complex chemical reactions follow one another until product formation.
In the case where one or two or perhaps more elementary reactions are common for two or more simultaneously (synchronously) proceeding complex reactions, these chemical events are interpreted in terms of chemical conjugation, but within the framework of coherent-synchronized reaction theory (see below).
Let us clarify what is meant by the term intermediate compounds, which includes intermediates and mediators:
intermediates: unstable highly reactive particles, which are not included in the final equations of complex reactions;
mediators: stable compounds of complex reactions, which are included in the final gross equations.
The mechanism of a complex chemical reaction always consists of a combination of elementary reactions of intermediates and mediators, the integration of which always leads to the stoichiometric equation.
The microscopic consideration of chemical kinetics is associated with the behavior of intermediates and molecules in particular quantum states.
Thus, any chemical transformation of substances is an ensemble of microscopic and macroscopic factors.
In microscopic kinetics (stochastic process), chemical inter actions are considered within the framework of the "theory of an elementary act", whereas macroscopic kinetics refers to the average (statistical) value of the dynamics of a huge number of "microscopic acts" as "random events of a probabilistic nature".
It is obvious that today we can say that modern chemistry should be considered in the context of stochasticity and randomness.
Any chemical system is carried out in either a static or open system. The static system is always closed (when there is no material exchange with the external environment), and the reaction medium volume is constant. A characteristic feature of open systems is their steady state due to mass exchange with the external environment.
Among specific catalytic reactions, the so-called autocatalytic reaction has specificity. Autocatalytic reactions are reactions where the final product of one of the reactions is a catalyst for the subsequent reaction from the beginning of the process. In some cases, it is absolutely necessary for the initial reaction mixture to have a catalyst-initiator of the primary reaction in at least very trace amounts. At the very beginning of the process, there is an accumulation of auto-catalyst in a chemical system, and at a certain time, this leads to a sharp increase in the speed of the main process. Autocatalysis especially occurs in static systems, where one stationary state at t^-ro (t - astronomical time) is observed for a simple reaction, and several states, for complex reactions.
The autocatalysis of multistage processes can occur in one or in several elementary reactions and, as a result, with multiple steady states. In this regard, autocatalytic reactions hold a special place in the interpretation of oscillating reaction mechanisms [10].
Hence, a few words must be said on the interpretation of the nature of oscillating processes in chemical systems. In the open (flow) system, the reaction medium is continuously supplied with the starting reagent to maintain its concentration constant, and after some time, the system reaches the stationary state. Self-oscil-
lations of substance concentrations in complex chemical systems are dependent on a fixed point. Under certain conditions, there is "an abrupt transition from one type of fixed point to another, which is called the bifurcation" [8, 9].
The autocatalytic component of a complex chemical reaction is always responsible for the oscillatory kinetic curves if the formed au-tocatalyst works in the diffusional zone. We believe that an open reaction system, due to the intensive mixing, can transfer the conditions for autocatalysis implementation to the kinetic mode, and its kinetic curves will have a, normal for it, S-shaped form [1].
In 1921, Bray discovered "cyclic changes in color of the solution caused by periodic formation and expenditure of the reaction intermediate - molecular iodine" in the hydrogen peroxide reaction with iodic acid.
The mediator is a stable compound (the mediator), which can be accumulated in the kinetic zone and separated from the solution under certain conditions. In the kinetic sense, this reaction is a usual consecutive one.
However, if this reaction is implemented in the diffusional zone, there is a condition for the oscillatory response. In fact, the formation of the intermediate substance (mediator) and its expenditure depend on the rate of reagent transport to the site where the active center was formed (in this case the iodine molecules). As long as the reagent reaches the active center (mediator), the corresponding experimental curve of its accumulation is at a maximum; and therefore at the real (astronomical) time interval, the specific coloring is observed. Once the reaction involving the mediator has proceeded, the curve goes to a minimum, and as a result, the characteristic coloration disappears. This oscillation process can periodically be visually observed, making a visual impression on the viewer.
Discovered by B.P.Belousov in 1951, the oscillating reaction of the oxidation of citric and malonic acids by bromate ions in the presence of cations of cerium has received an incomplete physicochemical justification in the works of A.M.Zhabotinsky.
The essence of these concentration oscil-
lations is that with "specific ratios between the concentrations of reagents, there is a periodic change in the color of the solution. The oscillation mechanism is caused by the appearance of Ce4+ cations, which give color to the solution. These cations are formed by the oxidation of Ce3+cations, which do not add color" [10].
The long induction period that is observed in the process of Br- anion accumulation is proof of its autocatalytic role in the reaction system. Ce3+and Br- are "co-catalysts" in the implementation of the oscillatory mode in the oxidation reactions of malonic and citric acids.
As far back as 1952 [11], A.M.Turing found that "the combination of chemical oscillations with the diffusion of molecules" is the main reason for the oscillation that occurs between the maximum and minimum reaction product (mediator) concentrations.
Oscillatory reactions are essentially caused by the direct dependence of the mediator concentration on the rate of diffusion to the reaction site, which precludes the process of their synchronization.
All these oscillatory reactions have a common property associated with their process cyclicity: the rate of reagent diffusion to their reaction site is lower than the chemical reaction rate. In this case, the cyclicity consists of an alternation between a physical process (of diffusion) and the chemical reaction itself. Autocata-lytic processes of this type cannot be synchronized or coherent, although they are oscillating reactions.
Autocatalysis may proceed in the kinetic zone of the chemical reaction, and its kinetic regularities are typically S-shaped, which also excludes the oscillatory nature of the reaction.
Today, we can cite dozens of concentrated oscillatory processes that have a common feature - non-linearity - associated with the au-tocatalytic nature of the process [9, 10].
All these reactions are generally carried out in batch reactors, i.e., static constant volume systems. These periodic reactors are inefficient and used predominantly in practice in the production of light-duty products. High-flow reactors (open systems) operating in two different
modes - complete mixing and plug flow - are used in bulk manufacture.
Gas phase reactions are studied mainly in flow reactors in plug flow mode, where the steady state is reached quickly. An important aspect is that the level of reagent conversion depends on the time of reagent residence in the reaction zone, regardless of its implementation system (static or flow).
Flow reactors in plug flow mode are more effective than those in the mode of total mixing (ideally by approximately 30%).
The majority of chemical and biochemical processes proceed in the kinetic zone. Therefore, the synchronization of two or more chemical reactions is of special importance.
As shown below, the observed intermodulation of synchronized chemical reaction yields is clearly displayed in the kinetic zone and represents a valid tool for the manipulation of their rates.
The kinetic zone of the chemical reaction process is characterized by a much lower rate of chemical transformation than the rate of reagent transport to the active site, i.e., the diffusion rate of the reagents is much higher than the chemical reaction rate. As follows from these canonical identifications, only the kinetic zone is associated with the coherent synchronization of two or more chemical reactions. This is the main reason for the significant differences between the various types of synchronous processes.
Until recently, the expression "chemical interference" was absent from chemical dictionaries; the terms "complex reactions", "chemical conjugation", and "induced reactions" were more commonly used. This new term was coined in the late 1980s. It unites most aspects of the former terms concerning the interaction and mutual influence of chemical reactions. This new term, unappreciated at first sight, is not merely to be attributed to an author who thought up a new chemical term, but it is actually of deeper significance. It is probably associated with the complex situation appearing in chemistry and biology, when the fundamental tendency of modern biochemical investigations concludes in the development of a holistic approach to problems.
Therefore, some chemical and biochemical processes may be barely, or sometimes not at all, understood without this approach.
Chemical interference reflects a holistic approach to complex processes proceeding in chemical and biological systems, not with respect to their components, as is commonly practiced, but rather in the characterization of their phenomena This, in a real sense, justifies the introduction of a new term.
At the present time, the prospect of using chemical interference as an event becomes clearer still. It may well form the basis for the creation of energetically favorable, highly selective and environmentally pure processes and therefore may affect economic aspects of the applied developments.
Chemical interference and self-organization of chemical systems at the macroscopic level
Chemistry is on the brink of establishing self-organizing and self-assembling chemical systems where algorithms allowing a group of chemical reactions to combine in an ensemble to obtain a final product in a single reaction medium with high selectivity in a short time are implemented. Before starting to develop the principles of construction of the chemical system mentioned above, it is necessary to understand, at least in general terms, how biochemical systems are self-organizing, to use nature as a model for the concept.
In biochemical systems, an ensemble of enzymes, which are implemented through the coordinated work of algorithms of different enzymes, ensuring the coherence of simultaneous biochemical reactions, are formed. One example is the mitochondrial energy process, wherein two synchronous flow coherent biochemical reactions-respiration and oxidative phosphorylation-are realized through self-organization in the inner surface of the mitochondrial membrane enzyme ensemble.
The overwhelming majority of enzyme ensembles are organized in living organisms in such a way that the coherent synchronized biochemical reactions proceed in a highly effective
and self-organized way. Unfortunately, these reactions have not been practically implemented to enable the development of similar chemical systems, probably due to the lack of adequate theories explaining the working principles of enzyme ensembles (unlike the working principles of individual enzymes). Exceptions include the interpretation of the mechanism of the coherently synchronized reaction of H202 decomposition and the oxidation of substrates by hydrogen peroxide on a biomimetic catalyst [1].
Most chemical reactions in basic and applied research are studied in conditions where only one reaction is implemented in the system, in the absence of coherent interactions with other reactions. This implies that chemical-technological processes developed on this basis are mainly focused on generating a target material via a series of chemical-technological stages, each of which obtains a particular pre-product for the following process.
Nature, by contrast, shows us another way for the synthesis of biological substances in the cells of living organisms, where a set (ensemble) of enzymes immobilized on intracellular membranes implement the process in the mode of the coherent synchronization of two or more biochemical reactions.
Theoretically and experimentally, we have developed a model of coherent chemical reactions for a very simple case: a reaction system consisting of two simultaneous reactions -H202 decomposition and substrate oxidation -that coherently interact.
The coherence of synchronous reactions forms the kinetics of this phenomenon in the form of a chemical interference pattern.
From our point of view, coherently synchronized reactions, consisting of only two reactions, can be accepted as a simple interferen-tial cell.
We can assume that more improved and complex interference patterns will consist of interferential cells. The basis for this pattern will be the concept of the multiplicity of coherently conjugate synchronous reactions.
It is obvious that interference structures in physics and chemistry are fundamentally different: in the former case, they are of a static
nature, whereas in the latter case, they are of a dynamic nature.
However, they have one common property: any change in any simple structure of the interference pattern becomes immediately known to all its elements, which in turn become adjusted to this change. This unusual property, in our opinion, should be the basis for the self-assembly and self-organization of complex systems of chemical and biochemical reactions.
In other words, it is due to the ensemble of coherently interacting chemical reactions that the system has the property of self-regulation. This paradigm may be useful in the quest to decipher the chemical and biochemical mechanisms of the actions of chemical and enzymatic reaction ensembles and possibly also for the understanding of cognitive process mechanisms.
The selectivity of enzymes on the substrate in the ensemble is the essential property that allows them to choose out of the large number of cellular materials the one that they are focused to convert to.
Thus, an ensemble of enzymes, due to its high level of organization, ensures the formation of the final product via the coherent mechanism instantly.
From this point of view, the selectivity is not a necessary function for the enzymes acting alone out of the ensemble, where as it is during their coherent functioning.
The synthesis of a target product in a living organism at the cellular level is carried out practically in no time, and this is possible only in conditions of chemical interference. Otherwise, the synthesis of target products via serial and series-parallel mechanisms would require a much longer time, which is not acceptable for living organisms.
On the basis of the coherence of the synchronized reactions, we should expect significant changes in the direction of revolutionary chemical technologies in macroscopic chemistry and in the chemical industry.
Interaction types
The total scheme of the conjugated process is as follows [12]:
A + In = RP (primary reaction), (1)
A + Acc = RP (secondary reaction), (2)
where RP is the reaction products.
It should be noted that the acceleration of one reaction by another may also be manifested without chemical induction, e.g., via the induction or synthesis of a catalyst for one reaction in another. The reciprocal influence of synchronously proceeding reactions in the system comprises a much wider range of events than does chemical induction.
Obviously, chemical induction is of great interest because, on the one hand, it allows the induction and acceleration of a non-spontaneous reaction and intrinsically remains the unique method by which to effect such reactions (except for reactions proceeding under the influence of photochemical or ionizing radiation). On the other hand, chemical induction plays a significant role in biochemical processes.
What is the principal difference between saying that the primary reaction "induces" and saying that it "performs effective work"? In principle, another reaction may be "induced" by initiation, as well as by the synthesis of a catalyst in the primary reaction. In these cases, the primary reaction does not perform (thermodynamical-ly) effective work for the secondary reaction (au-tocatalysis) to proceed. As defined, a catalyst is unable to make effective work, and in initiation, the target reaction is developed by a self-reaction pathway and needs a "trigger mechanism" only at its initial stage. In both cases, the target reaction is necessarily spontaneous.
In chemical conjugation, the primary reaction continuously induces a non-spontaneous process, making effective work during the entire reaction period. This is possible only during the change in the reaction mechanism or the target reaction type.
In principle, the connections and interactions between complex chemical reactions may be the most varied. Figure 1 shows the most significant of them, illustrating the layout of the most commonly known complex reactions: parallel, parallel-consecutive, and conjugated. At the moment, it should be noted that these schemes do not describe the mechanisms of the processes at the level of elementary reactions.
The interaction in consecutive reactions is carried out via the synthesis of an intermedi-
ate product at the first stage that is the precursor of the second stage. Hence, the increase in the first complex reaction leads to an expected increase in the other dependent reaction.
In Figure 1, conjugated processes are shown by a scheme clearly indicating its main features. In particular, it is clear that the inter-
mediate compounds formed in the primary reaction induce and speed up the non-spontaneous secondary reactions between the actor and the acceptor. Hence, the type of secondary reaction is most often changed, and in a transformed shape, becomes a spontaneous process.
Fig. 1. Schematic representation of interrelated reactions.
Similar to conjugated (interfering) reactions, parallel reactions must be synchronous, which is their obvious fundamental property.
Meanwhile, consecutive reactions may never be synchronous. This is the principal difference between the two systems of synchronous and usual reactions. As a matter of fact, the final product of the first stage of the consecutive reactions is the initial compound for the second stage, so these stages may never be simultaneous (synchronous). Thus, the main difference between synchronous parallel and conjugated (interfering) reactions is that the first type eliminates even a possibility of interaction, whereas in the second case, they may only be interacting reactions.
Three-component coherent synchronized reactions
One common type of actor participation in the induction of the secondary reaction is its transformation to a reactive particle under the inducer effect. This newly formed particle then reacts with another substance (acceptor)in the secondary reaction. Therefore, the actor participates in the gross equations of both conjugated reactions which, finally, are reduced to the widespread form of conjugated reactions (1) and (2).
Before discussing the theoretical features of coherent-synchronized reactions, let us consider the classic three-component coherent reaction
A + In ri >X r >B +..., (3)
A + Acc —^ C +..., (4)
where X is a highly active intermediate compound.
To demonstrate, the chemical conjugation mechanism may be presented by the following generalized scheme
vA + In ^ X -
j_
2 Acc
^FP ^FP
(5)
(where v is the stoichiometric coefficient). Comparing this scheme with its common shape expressed by reactions (3) and (4), it should be noted that it gives the best illustration of the role of the intermediate substance X (mediator), which is common to both conjugated reactions, and the inducer is expended in amounts related to the A expenditure in both reactions. The highly active intermediate particle X is a bifurcation center, whereby there is chemical interference in the form of two completely coherent kinetic curves.
For the scheme under consideration, the following expression may be deduced
=( /a, + /2
(6)
Where fA and fA are the amounts of actor used for the synthesis of the final products in the prima-
ry (3) and secondary (4) reactions, respectively.
Substituting equation (6) into the equation of the induction factor I=/Accfnd, the following expression is deduced
D = v
D = v
Г f f yi J a J A2
fAcc JAcc
(7)
Ai + 'A2
Acc
Acc
where factor D is called the determinant.
What is the principal difference between conjugated and coherently synchronized reactions? In principle, they are practically described by the same chemical equation, but with different features, as shown in Figure 1.
The conjugation of synchronous reactions in this scheme is shown by an arrow indicating the unilateral influence of the primary reaction on the secondary.
On the other hand, both reactions affect each other in coherent synchronized reactions, indicating the presence of feedback. That is the two-way nature of the interaction of synchronized reactions, which is responsible for the interference pattern - the primary reaction speeds up the secondary, which in turn slows the former down, and vice versa. This chemical interference is dynamic in nature and is clearly described by the conjugate kinetic regularities of the two reactions.
The term "inducer" in both cases retains its universal significance. In fact, the conjugate reactions are the reflection of the coherent-synchronized reactions in the forward direction and are described by the conjugate kinetic regularities of the two reactions. "The forward direction" can be considered a particular case of coherent-synchronized reactions. Hence, the concept of coherent-synchronized reactions is universal, and its mathematical apparatus is simple, and therein lies its beauty.
Note, also, that for chemical induction, equation (6) is always correct.
Let us emphasize an important point once
again: the actor expenditure in conjugated reactions is as high, as it is used at the stage of the formation of the inducing intermediate in the primary reaction, as when active sites are formed. These sites are intermediate products, a definite part of which is spent in the formation of final products in the primary and secondary reactions.
It is common knowledge that the primary reaction usually proceeds in several stages (two, at least), and it is of importance that the reactive sites generated in it are mainly expended in the target, secondary reaction. For this purpose, the stages that cause the accumulation of active sites must proceed at a higher rate than the following ones that give the final products of the primary reaction.
The analytical consideration of equation (7) leads to several important consequences for various forms of chemical interference [1].
Meanwhile, the catalyst may only cause or accelerate a spontaneous reaction and, at most, promote the achievement of outputs close to equilibrium, whereas chemical induction may cause outputs exceeding the equilibrium. In this regard, if in the primary reaction, active sites representing the catalyst for another synchronously proceeding reaction are accumulated, the latter reaction must be spontaneous, and the primary reaction does not perform effective work for its running. On the other hand, in chemical induction, intermediate substances are obligatorily consumed for the secondary, non-spontaneous reaction, so the chemical energy released in the primary reaction is consumed, and effective work is therefore performed.
Therefore, the catalyst synthesized in the primary reaction is unable to perform effective work in the secondary reaction, and such reactions may not be classified as conjugated because this would entirely contradict the notion of chemical induction.
It is also known that the majority of processes important in biochemistry represent conjugated catalytic reactions. Conjugated catalytic reactions obey the regularities typical of chemical induction, i.e., D<v.
In fact, in the latter case, the catalyst (in-
jected into the system with initial reagents) only speeds up the interaction between the IP of the primary reaction and the acceptor. Therefore, D<v, and consequently, chemical conjugation takes place. This means that no matter how the reaction between the acceptor and the intermediate product is intensified by the catalyst, the induction factor (the determinant) may not exceed v.
When analyzing conjugated catalytic reactions, it should be taken into account that the amount of acceptor involved in the reaction may be significantly increased by the application of a catalyst in both conjugated reactions.
The catalyst application to the primary reaction at the stage of the intermediate product formation will promote its quick accumulation in the system in amounts much higher than for its non-catalytic run and will soften the reaction conditions. The secondary reaction is also accelerated, and its progress is stipulated by the presence of the intermediate substance of the primary reaction.
When D>>v, the primary reaction generates, in the system, a catalyst for the secondary, spontaneous reaction. Hence, chemical induction is absent. In this regard, a very important conclusion can be drawn: the determinant value of the chemical system characterizes the conjugated reactions and represents a common induction factor only in the case where its value fulfills the inequality 0<D<v. Note, also, that this inequality is typical only of systems in which coherent synchronization occurs.
Nevertheless, equation (7) may help in determining the determinant and detecting the type of interrelated reactions from it. It should be noted here that, in the broad sense of the word, interrelated (interfering) reactions are only those proceeding via general intermediate sub-
stances, capable reagents, initiators or catalysts of secondary reactions. Otherwise, this class of reaction may be added to by consecutive reactions, which are not coherent (nor synchronized).
The overwhelming majority of biochemical oxidation processes represent coherently synchronized catalytic (enzymatic) reactions. Therefore, it is of great importance to distinguish a catalyst and an inducer because any mistake would cause an incorrect interpretation of the chemical mechanisms of the reactions proceeding in the biological system. (For instance, redox reaction catalysts are often mistaken for inducers).
Among interrelated reactions, initiated radical-chain reactions are the most widespread. At the initiation process, the synthesis of highly reactive intermediate compounds (free radicals, in particular) is a necessary condition for the target reaction intensification. However, initiating substances are used as additive increments, and the chain initiation stage must proceed at a much lower rate than the chain propagation stage. Otherwise, the chain length becomes shorter, and the chain transformation of the substrate becomes ineffective [13-15]. In other words, initiators act as "triggers" of the radical or chain process. From these positions, interacting and initiated reactions are rather similar: a catalyst is synthesized in the primary reaction, whereas other reactions generate active sites shaped as free radicals, etc.
Figure 2 shows the determinant scale, which makes the detection of one type of reciprocal influence of chemical reactions (chemical interference) or another, as well as chemical interference in the reaction mixture, easier.
D=0 D=v/2 D=v D>v D>>v
Fig. 2. Scale of chemical interference determinants: D = 0-v, the region of chemical conjugation; and D>0, the region of the occurrence of other interrelated reactions.
Kinetic studies of a chemical system with the interaction between reactions, based on the experimental data, allow selections from among various types of mainly interfering chemical reactions. Therefore, chemical interference investigations may be useful for the study of reaction mechanisms.
As noted above, chemical interference can be one of the forms of self-organization of complex chemical systems, which is described by the determinant equation (7). The fact that the vast majority of "in vivo" enzymatic reactions are synchronized and coherent supports this consideration. As shown below, the determinant equation is a very useful and easily adaptable kinetic apparatus for solving complex chemical problems.
The physicochemical features of chemical interference are displayed by the theoretical kinetic curves in Figure 3 and allow the discovery of some shapes, which will be discussed below.
These idealized curves were composed with the hypothesis that primary reaction (1) in the absence of secondary reaction (2) proceeds until the end; i.e., its initial reagents are consumed completely. Therefore, the acceleration of the secondary reaction is studied under conditions in which the primary reaction runs completely to its end.
The curves in Figure 3 a show that in the
absence of the secondary reaction (2), the primary reaction (1) proceeds with almost 100% consumption of the reagents. As the secondary reaction (2) products are accumulated, the quantity of primary reaction products decreases, and both curves pass through extreme points (peaks). According to theoretical notions, the maximum of reaction (2) corresponds to the minimum of reaction (1). In the case where, due to kinetic reasons, reaction (2) is synchronized with the primary reaction (1) with some delay, a phase shift (A) occurs, shown by a dashed line in Figure 3 a. The maximum on this curve is right-shifted by the A value. In other words, the phase shift represents the difference between the primary reaction minimum and the secondary reaction maximum.
Based on kinetic regularities following from the type of curves, one may make an important conclusion that for every particular condition, the totality of the reaction products will correspond to a constant value of the actor consumption, or, in accordance with the stoi-chiometry (coherent correlation) of the inducer and the assumption (e.g., postulation) of its complete consumption, the following expression becomes valid:
coherent correlation
1 f = fn=A+4=/;+/;=f;=-=const. (8)
Fig. 3. Theoretical kinetic curves for interfering reactions (primary 1 and secondary 2) of extreme (a) and asymptotic (b) types; A is the phase shift.
It is assumed that equation (8) is the coherence correlation for chemical interference, at least for the case in which the D value varies between zero and v, i.e., coherent synchronization of reactions takes place.
An important consequence of equation (8) should be outlined: the effective interference between two chemical reactions is observed in the case where, in the absence of the secondary reaction, the primary reaction proceeds completely to its end in the entire range of conditions.
Another case, also shown in Figure 3 b, is characterized by curves free from extreme points, approaching the X level. Such curve shapes indicate a zero concentration of the actor and highly reactive intermediate particles in the area where the asymptotic curves approach the X level most closely. Therefore, at the asymptotic approach, no products are formed by the interfering reactions. The coherence condition, displayed by equation (8), is also fulfilled in this case.
Other cases, mostly associated with the incomplete (i.e., partial) proceeding of the primary reaction in the absence of the secondary reaction and its complication by side reactions, especially with the participation of an inducer, may be realized, as well. In the cases under consideration, as the actor or inducer consumption per primary and secondary reactions are calculated, the amounts consumed for the synthesis of the side products must be subtracted from the total amount or, at incomplete consumption, the amounts of non-reacted A or In compounds.
Note that the X line in Figure 3 b may be located above or below the 50% level of the product accumulation from the two interfering reactions or the actor (inducer) and acceptor consumptions. The line location above the X line means that the greater part of the total, highly active intermediate particles (active sites) is consumed for the secondary reaction product formation, and vice versa, when the line is below the X level.
The dashed curve in Figure 3 b shows the phase shift, the origin of which is similar to that in Figure 3 a.
For coherently synchronized reactions, the maximum high determinant value equals v (D=v). This means that only a secondary reac-
tion proceeds in the system, coinciding by stoichiometric parameters with the corresponded conjugated reaction. Simultaneously, the level D = v is the lowest for the initiation, autocataly-sis, chain and other types of interfering reactions which, in the previous case, are reduced to a stoichiometric reaction. Hence, when considering the suggested theory from the position of the correspondence principle, the following conclusion can be made: under the condition D = v, the conjugated, chain, initiated and auto-catalytic reactions are necessarily reduced to stoichiometric reactions, i.e., described in the framework of the classical theory of chemical reactions. Formally, the transition to a stoichiometric reaction happens at D ^ v, which emphasizes the general type of the new notion of interfering chemical reactions.
Coherent synchronized oxidation reactions by hydrogen peroxide
The examples given below - methane oxidation to methanol, ethylene oxidation to acetal-dehyde and ethanol, propane oxidation to isopro-panol, propylene epoxidation and hydroxylation, and ethanol oxidation to acetaldehyde - demonstrate experimental approaches to the study of interfering reaction dynamics and, with the help of the determinant equation, the potential abilities of the reaction media are assessed, and the type of chemical interference, determined.
Methane oxidation
The monooxygenase reaction for synthesizing methanol from methane was studied in the presence of cytochrome P-450 biosimulators, such as ferroprotoporphyrin catalysts with carriers (Al2O3, NaX, aluminum-chromium-silicate or aluminum-magnesium-silicate). This reaction helped in the detection of the highest catalytic activity for PPF3+OH/aluminum-magne-sium-silicate [11], which also displayed the highest catalytic activity for the hydroxylation reaction. As shown, the optimal hydroxylic activity of the catalyst is displayed in the initial 30 min of its operation (methanol output equals 60 wt.%, selectivity is 97 wt.%). Figure 4 shows that the kinetic dependence of the methanol output on the temperature has a maximum at
1800C and that the curve of the molecular oxygen yield has a corresponding minimum. In this experiment, the methanol yield reaches 46.5 wt.%, at which the methane conversion rises to 48wt.%. The non-target products CH2O and HCOOH in low amounts (« 1.5%) and temperature have no effect on their yield. A comparison of curves 2 and 5 in Figure 4 in the framework of the ideas discussed above shows their reliable analogy with the theoretical curves in Figure 3 a. Some deviation of the coherence (find) from the theoretical level may be explained by the synthesis of side oxidation products and systematic errors, which usually accompany any chemical experiment. However, its value (find) obeys the main coherence condition following from equation (8). More precisely, fnd~constant
for current reaction conditions. This value may be simply calculated from the data of Figure 4 a. A graphical presentation of chemical interference, shaped as asymptotically approaching curves in another range of the reaction conditions, is plotted in Figure 4 b. A comparison of the experimental curves in Figure 3 b with the theoretical ones in Figure 3 b indicates their adequacy and relates the observable chemical interference to the case above X, i.e., when the CH4 oxidation rate slightly exceeds the rate of molecular oxygen synthesis.
In the chemical system studied, a biosimulator catalyzes two interrelated (catalase and monooxygenase) reactions, which are synchronized and proceed according to the following mechanisms (Figure 5), where ImtOH is a
wt. % 100
wt. %
240 t, 0C
100
2.4 5.8 10,2 11,6 T, c
Fig. 4. Dependencies of methane hydroxylation outputs on temperature (a) and contact time (b) at 1800C. 1 - CH4 conversion, 2 - CH3OH output, 3 - CH2O and HCOOH outputs, 4 - selectivity, 5 - O2
output ratios: CH4:H2O2 = 1:1.4 (a) and 1:1.8 (b); vrH V
CH4VH2O2
0.8 ml/h, [H2O2] = 20 wt.%.
a
Fig. 5. Mechanism of the coherent-synchronized catalase and monooxygenase (CH4+H2O2=CH3OH+H2O) reactions.
PPFe3+OH/AlMgSi biosimulator, and ImtOOH is a PPFe3+OH/AlMgSi intermediate compound: (1) primary catalase reaction and (2) hy-droxylation (secondary monooxygenase reaction).
Both reactions (1) and (2) in Figure 5 proceed via a general PPFe3+OH/AlMgSi intermediate compound, which is certainly the transfer agent for the inductive action of the primary reaction on the secondary reaction. The determinant calculated by equation (7), which allows the quantitative identification of the interaction between reactions, equals D = 0.48.
This indicates that reactions (1) and (2) are conjugated because the value obtained on the determinant scale of chemical interaction (Figure 2) falls within the range of chemical conjugation D<1) because in the current case, v=1.
Let us consider the experimental data shown in Figure 6 a and b, obtained for the homogeneous gas-phase oxidation of methane (or natural gas) by hydrogen peroxide to methanol under pressure [14]. The increase in contact time to 0.95 s (Figure 6 a) gives a maximum methanol output and a minimum oxygen output. A further increase in the contact time reduces the methanol output, whereas the molecular oxygen output increases. A similar kinetic regula-
rity is observed in experiments with variable pressure (Figure 6 b).
Thus, a comparison of the curves of molecular oxygen accumulation and CH4 consumption (or CH3OH accumulation) shows that the maximum CH4 transformation corresponds to the minimum O2 accumulation.
Chemical interference is clearly displayed owing to the almost 100% selectivity of the reactions: increased O2 synthesis induces a simultaneous decrease in CH4 transformation to CH3OH, and vice versa.
As the curves in Figure 6 a and b are considered from positions of coherence and possible phase shift, note that the particular reaction mixture differs from the mixtures considered above by a relatively low (approximately 20 wt.%) CH4 substrate conversion, although the H2O2 dissociates almost completely. This circumstance must be taken into account in the framework of the approach to such a case described above.
The chemical interference determinant can be experimentally determined by equation (7). For the current conditions of minimal O2 and maximal CH3OH outputs, D = 0.18. On the chemical interference scale in Figure 2, this value falls within the range for conjugated reactions.
p, atm
Fig. 6. Dependence of methanol output on the contact time (a) and pressure (b); T = 4000C, [H2O2] = 30 wt.% ; (a) - p = 7 atm; vCH4 = 31.4 l/h; vH2O2 = 0.18 l/h; CH4:H2O2 = 1:1.4 (mol) and (b) - %2O2 = 0.18 l/h; vCH4 =
62.41/h; CH4:H2O2 = 1:0.4 (mol).
It quantitatively characterizes the inductive action of H2O2 on CH4 oxidation and indicates the presence of high potential abilities to increase the induction effect of the system studied (theoretically, in the current case, D may increase to 1 or will tend to approach at least the 50% level). There are physicochemical experimental techniques that allow the manipula-
tion of conjugating reaction rates. On the other hand, not applying the method of stationary concentrations, the determinant equation (7) provides an opportunity to analyze the kinetics of complex reactions with insignificantly studied mechanisms. For these two reactions, the conjugation mechanism is
H2O2
->2* OH —
k2 h2°2 > h2o+ho2
k3 ch4
->h,o+ch;
3 ¿4 h2o2
->ch,oh+'oh
(9)
As follows from the determinant equation
D ( ^ + rA2 )
r =
CH4 V
or
гш4 = d fe[h2o2] + ¿3^4]) [oh]
(10)
r
Using experimentally obtained values of ch and D [14], the appropriate kinetic calculations were carried out. Therefore, equation (10) adequately describes the kinetics of interfering reaction (9).
Thus, the determinant equation was found to be useful for the analysis of the kinetics of complex reactions in that it made simpler the kinetic calculations in the determination of the kinetic model of interrelated and synchronized reactions proceeding in the reaction mixture, as well as the qualitative and quantitative assessment of the chemical interference itself.
Propylene epoxidation
The diagrams in Figure 7 illustrate the conjugation of two reactions: H2O2 dissociation and propylene epoxidation by hydrogen peroxide [15]. The rate decrease in biosimulator catalase activity product (O2) accumulation is accompanied by a rate increase in epoxidation product synthesis, and these processes interfere via a general highly active intermediating compound, per-FTPhFe3+OOH/Al2O3.
However, presenting the interference picture via a diagram has several principal disad-
vantages: 1) diagrams do not show how coherence is implemented; 2) phase shifts may not be shown; 3) maxima and minima in the accumulation of the products of both reactions are not shown; and 4) there is an absence of asymptotic curves.
Fig. 7. Hydrogen peroxide consumption (q) in catalase (a) and monooxygenase (b) reac-
tions with time of contact; C3H6:H2O2 = 1:1.2 (mol).
T = 200UC,
The advantage of the diagrams is that they are highly illustrative of the chemical conjugation between current reactions. Thus, diagrams help in demonstrating one of the aspects of chemical interference associated with the conjugation of the processes.
Ethylene oxidation
The gas-phase monooxidation of ethylene by hydrogen peroxide on a biomimetic heterogeneous catalyst (per-FTPhPFe3+OH/Al2O3) was
studied under comparatively mild conditions. The biomimetic oxidation of ethylene with hydrogen peroxide was shown to be coherently synchronized with the decomposition of H2O2. Depending on the reaction medium conditions, one of two desired products was formed, either ethanol or acetaldehyde.
In recent years, there has been considerable progress in studies related to the synthesis and development of biomimetic catalysts based on iron porphyrin complexes [1-5]. They simulate the main characteristics of enzymes (activity, selectivity, softness of conditions, mechanism of active center operation, etc.), in particular, cytochrome P-450.
Distinct from the known homogeneous catalysts modeling cytochrome P-450, heterogeneous iron porphyrin biomimetic catalysts of gas-phase monooxidation possess many technological advantages. For instance, the high-efficiency epoxidation and hydroxylation reactions are performed in the gas phase. This allows many factors to be excluded that substantially influence the catalyst activity in liquidphase oxidation (the nature of the solvent, reaction medium pH, etc.). In addition, the high selectivity of the processes in these works was also provided by the use of hydrogen peroxide as an oxidizer. As is known [9-11], hydrogen peroxide satisfies the requirements of the concept of "green chemistry" and is called a "green oxidizer". It follows that most of the organic reactions with the participation of hydrogen peroxide occur synchronously with its decomposition under coherent conditions of mutual strengthening and weakening. Thanks to the acid-base nature of the carrier (Al2O3) of the perFTPhPFe3+OH/Al2O3 biomimetic catalyst, the mechanism of the coherently synchronous monooxidation of ethylene is considered in terms of the concepts accepted for redox enzymatic reactions [1].
The temperature dependences of the yields of the coherently synchronous ethylene oxidation and hydrogen peroxide decomposition products, C2H5OH, CH3CHO, O2 and CO2, are shown in Figure 8. It follows from these dependences that the highest yield of ethanol is obtained at 1200C. An increase in temperature
Fig. 8. Temperature dependences of the yields of the ethylene monooxidation products
at CH2O2=30%, %2O2 =0.22 1/h, and C2H4:
H2O2 = 1:1.2; 1 - conversion of C2H4, 2 -yield of CH3CHO, 3 - yield of C2H5OH, 4 -yield of CO2, 5 - yield of O2.
noticeably decreases the yield of ethanol because of its transformation into acetaldehyde. These experimental data well agree with the results obtained in [16], where the peroxidase oxidation of ethanol into acetaldehyde was studied. Note that, at a low temperature, the yield of molecular oxygen is maximal; that is, the catalase reaction with the production of molecular oxygen largely occurs. The yield of O2 decreases as the temperature increases and is stabilized after a certain temperature is reached. The catalase reaction then has the lowest rate. Simultaneously, the conversion of ethylene into monooxide compounds is stabilized. This is evidence that, at the temperatures specified, the concentration of hydrogen peroxide is insufficient for the catalase reaction deepening and, therefore, ethylene monooxidation. The highest yield of acetaldehyde is limited to 35 wt.%, at 2000C [17].
It follows from the experimental data that the two synchronous reactions, catalase and monooxygenase, interact with each other. As a result, chemical interference is observed in the system, and the primary reaction strengthens the secondary one, which, in turn, decelerates the primary reaction. It follows that the synchro-
nous reactions are coherent, and, most importantly, the coherence condition
"0
' H2O2
ÍH-Ob. = flH2P2 + f2H2O2 = COnSt (11)
= const
is satisfied. Here, /H o2 is the initial amount of hydrogen peroxide (actor); and / H 0 and
/ h2o2 are the amounts of the actor (H2O2) consumed for the formation of the final products in the primary (catalase) and secondary (mono-oxygenase) reactions, respectively.
After the calculations of the experimental /1H20 (0.84, 0.78, 0.76, and 0.73 mole fractions) and / h2o2 values (0.16, 0.22, 0.24, and
0.23 mole fractions) for experiments with different hydrogen peroxide concentrations (Figure 8, curves 1 and 5) and the substitution of these values into equation (11), we see that the coherence condition is satisfied, 0.84 + 0.16 = 0.78 + 0.22 = 0.76 + 0.24 = 0.77 + 0.23 = 1.
It follows that the reaction system includes two coherently synchronous reactions, catalase and monooxidase [1, 18]. According to the generally accepted mechanism [17], both reactions occur via a common intermediate, per-FTPhPFe3+OOH/Al2O3, which transfers the inductive action of the primary reaction to the secondary one, that is, the process occurs under bifurcation conditions. This mechanism of the action of two complex reactions is based on the concept that the decomposition of hydrogen peroxide (the primary reaction) accelerates the secondary reaction of olefin monooxidation, and, conversely, the secondary reaction decelerates the formation of the primary reaction products by its occurrence. Such a chemical interaction of the reactions results in chemical interference in the dynamic (that is, time) mode. The effectiveness of the chemical interference in this reaction system is measured by its quantitative characteristic, as determined by the determinant equation [17].
Propane hydroxylation
Synchronizing hydroxylation and hydrogen peroxide decomposition with the use of a biomimetic catalyst allows these reactions to be performed under mutual intensification and
weakening conditions (chemical interference) and the rates of these reactions to be easily controlled under comparatively mild conditions. We used this nontraditional chemical experiment technology for hydroxylating propane with hydrogen peroxide to isopropyl alcohol in the presence of a biomimetic catalyst, namely, iron(III) perfluorotetraphenylporphyrin deposited on alumina.
The dependences of the yields of isopro-panol (z'-C3H7OH) and molecular oxygen (O2) in the oxidation of propane (C3H8) on the contact time t are shown in Figure 9.
Fig. 9. Contact time dependences of reaction product yields: 1 - O2 and 2 - /-C3H7OH (2400C, [H2O2]=20 wt. %, C3H8:H2O2 = 1:2).
It follows that the hydroxylating activity of the biomimetic is low at small t (t < 0.6 s), whereas, according to the O2 yield curve, the cata-lase activity prevails. The yield of /-C3H7OH and, accordingly, the conversion of C3H8 increases as t grows. Starting with t = 1.1 s, the synchronization of the catalase and monoox-ygenase reaction curves becomes obvious. The O2 yield curve for the catalase reaction shows that, at short t, virtually complete catalytic decomposition of H2O2 with the formation of O2 occurs because the rate of propane hydroxylation is then insignificant. The yield of z'-C3H7OH increases and reaches a maximum at t = 1.1 s as the consumption of H2O2 in the catalase reaction decreases. Further increasing t causes the synchronization of the yields of the catalase and monooxygenase reaction products.
Clearly, this is evidence of the interaction (conjugation) of these two reactions. Note that the complete consumption of hydrogen peroxide was observed in the entire range of the contact time variation. This consumption was distributed between the catalase and hydroxylation reactions according to their kinetics.
This leads us to conclude that, under the given conditions, the sum of the yields of the final products of the synchronous reactions corresponds to a constant consumption of H2O2 (actor), and, in our experiments (where H2O2 is completely consumed in the two reactions), the following equation is valid
N0 = N1 + N2=const, (12)
where No is the initial amount of hydrogen peroxide consumed in both reactions, and N7 and N2 are the amounts of hydrogen peroxide consumed in the catalase and monooxygenase reactions, respectively.
In agreement with the theory of interactions between synchronous reactions [1], it follows from (12) that the condition of the coherence of chemical interference is met in the process under consideration. Because of the coherent interactions of two synchronous reactions, the rate of one of them (catalase reaction, Figure 10) decreases, whereas that of the other reaction synchronized with the first one (hydroxylation reaction) increases, and vice versa.
Fig. 10. Temperature dependences of consumption of H2O2 (1) in the catalase reaction and (2) in the hydroxylation reaction.
The experimental determinant value for the optimal hydroxylation conditions (2400C, C3H8: H2O2=1:2 molar ratio, concentration of aqueous
solution of H202=20 wt%, vc3H8 =0.3 1/h, =
4.24 ml/h, and t = 1.2 s) calculated by (4) is D ~ 0.4. According to the scale of chemical interference [1] determinants, this value is in the region of chemical conjugation when the primary reaction of H202 decomposition induces the secondary one of C3H8 hydroxylation. It follows that the two synchronous reactions that occur in the system (the catalase and hydroxylation reactions) interact with each other [the coherence (fnd ~ const.) and induction (D ~ 0.4) condition); are fulfilled] to produce a chemical interference picture in the form of synchronized and mutually related kinetic curves of the catalase and propane hydroxylation reactions (Figure 10) [18].
Ethanol oxidation
The dependences of the yields of acetal-dehyde (CH3CH0H) and molecular oxygen (O2) in the selective oxidation of ethanol in the presence of biomimetic catalysts on the contact time are shown in Figure 11. At short contact times (up to t = 2.3 s), the yield of acetaldehyde (the peroxidase reaction product) substantially increases and the catalase activity (the yield of O2) decreases on all three catalysts. The peroxidase
Fig. 11. Contact time t dependences of the yields of the products of selective oxidation of C2H5OH [(1-3) CH3CHO and (4-6) O2] at
1800C and
CH2O2 =20
wt.% on (1, 4)
TPhPFe3+OH/Al2O3, (2, 5) PPFe3+OH/Al2O3. and (3, 6) per-FTPhPFe3+OH/Al2O3.
activity decreased and the catalase activity, conversely, noticeably increased as t grew larger. This makes it obvious that the kinetic curves of the catalase and peroxidase reactions are synchronized, which is doubtless evidence of the interaction between these two reactions and their coherent character [16].
Because of condition of the coherence of chemical interference /0 = f1+f2 = const. resulting from the interaction of two synchronous reactions, the rate of the catalase reaction (the decomposition of H2O2) decreases as the rate of the other (peroxidase) reaction, synchronized with the first one, increases, and vice versa. Such dependences are evidence that the two reactions (catalase and peroxidase) not only occur synchronously but also coherently interact with one another [1, 19].
References
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2. Nagiev T.M. Interrelated reactions and chemical interference // Russ. J. Phys. Chem. 1994. V. 68. P. 456-460.
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12. Шилов Н. О сопряженных реакциях окисления. М.: Товарищество типографии А.И.Мамонтова. 1905. 304 с.
13. Benson S.W. Thermochemical Kinetics. John Wiley & Sons, IMC. New-York-London-Sidnay. 1968. 308 р.
14. Nagiev T.M., Faradzhev E.G. and Mamedov E.M. Oxidation of methane to methanol by hydrogen peroxide under pressure // Russ. J. Phys. Chem. 2001. V. 75. P. 50-56.
15. Nagiev T.M., Gasanova L.M., Zulfugarova S.Z., Mustafaeva Ch.A. Oxidation-and-heating-stable Fe(III) perfluorotetraphenylporphyrincatalyst immobilized on alumina // Russ. J. Phys. Chem. 1996. V. 70. P. 1911-1916.
16. Gasanova L., Mustafaeva Ch., Nagieva I., Abbasov A., Magerramov A., Terner J., Nagiev T. Selective biomimetic oxidation of ethanol by hydrogen peroxide on immobilized ironporphyrincatalysts // Russ. J. Phys. Chem. 2005. V. 79. P. 382-388.
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18. Abbasov A.A., Zulfugarova S.Z, Gasanova L.M., Nagiev, T.M. Hydroxylation of propane with hydrogen peroxide on Fe(III) per-fluoro-tetraphenilporphyrin deposited on alumina // Russ. J. Phys. Chem. 2002. V. 76. P. 1591-1596.
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SiNXRONLA§DIRILMI§ KlMYOVi REAKSiYALARDA MAKROSKOPiK KOHERENTLiK: KEMYOVi
SiSTEMLORlN OZUTOSKiLLONMaSiNa YOL
T.M.Nagiyev
Kimya 6zuta§killanan va 6zubirb§an kimyavi sistemlarin yaranma qovu§aginda yerla§ir; sistemlarda yerim yetirilan alqoritmbr son mahsulun bir reaksiya muhitinda qisa muddat arzinda, yuksak segicilikla alinmasi ugun kimyavi reaksiya qruplarina ansambl kimi birla§maya imkan verir. Canli orqanizmda maqsadli mahsulun huceyra saviyyasinda sintezi demak olar ki, darhal ba§ verir; bu isa yalniz huceyra saviyyasinda gedan kimyavi reaksiyalar ansanbli kimi koherent sinxronla§dirilmi§ reaksiyalar §araitinda mumkundur. Taassuf ki, bu reaksiyalar ferment ansambllarin i§ prinsipini (fardi fermentlarin i§ prinsipindan farqli olaraq) izah edan adekvat nazariyyalarin movcud olmamasi sababindan tacrubada analoji kimyavi sistemlarin inki§afi ugun hayata kegirilmami§dir. Koherent sinxronla§dinlmi§ reaksiyalarin i§bnmi§ makroskopik nazariyyasi eksperimental tadqiqatlarla adekvat §akilda tasdiq olunmu§dur. Burada
biz koherent sinxronlaçdmlmiç reaksiyalann eksperimentla tasdiq olunmuç modtlini va onun determinant tanliyindan va koherent korrelyasiyadan ibarat riyazi aparatini taqdim edirik. Belalikla, reaksiya ansambllarinin ôzutaçkillanmasi eyni zamanda ham guclana, ham da zaiflaya bilar, demali bu sababdan induksiyalanmiç makroskopik koherentlik bir neça ferment ansamblinin taçkilina kômak edan prinsipin asasi kimi taklif oluna bilar.
Açar sozbr: koherent sinxronla§dmlmi§ kimyavi reaksiyalar, ôzutaçkiïïanan kimyavi sistemlar.
МАКРОСКОПИЧЕСКАЯ КОГЕРЕНТНОСТЬ В СИНХРОНИЗИРОВАННЫХ ХИМИЧЕСКИХ РЕАКЦИЯХ: ПУТЬ К САМООРГАНИЗАЦИИ ХИМИЧЕСКИХ СИСТЕМ
Т.М.Нагиев
Химия находится на грани создания самоорганизующихся и самообъединяющихся химических систем, в которых выполняются алгоритмы, позволяющие группе химических реакций объединяться в ансамбле для получения конечного продукта в одной реакционной среде с высокой селективностью за короткое время. Синтез целевого продукта в живом организме на клеточном уровне осуществляется практически моментально, а это возможно только в условиях когерентно-синхронизированных реакций, которые представляют собой ансамбль химических реакций на клеточном уровне. К сожалению, эти реакции не были осуществлены на практике для развития аналогичных химических систем, вероятно, из-за отсутствия адекватных теорий, объясняющих принципы работы ферментных ансамблей (в отличие от рабочих принципов индивидуальных ферментов). Разработанная макроскопическая теория когерентно-синхронизированных химических реакций была адекватно подтверждена экспериментальными исследованиями. Здесь мы предлагаем экспериментально подтвержденную модель когерентно-синхронизированных реакций и ее математический аппарат, состоящий из уравнения детерминанты (определителя) и когерентной корреляции. Таким образом, самоорганизация ансамбля реакций может быть усилена и ослаблена в одно и то же время и, следовательно, индуцированная макроскопическая когерентность может быть заложена в основу принципа, согласно которому организуются различные ферментные ансамбли.
Ключевые слова: когерентно-синхронизированные химические реакции, самоорганизующиеся химические системы.
