Specific features of oxidation of ferrocenylacetic acid with molecular oxygen in the absence and in the presence of Bronsted acids

Article abstract of DOI:10.1134/S107036320911005X

Comparative analysis of the specific features of autooxidation of ferrocenylacetic acid (FcCH₂COOH) in organic solvents at 30-50°C in the absence and in the presence of trifluoroacetic acid (processes 1 and 2 respectively) was carried out. It w

Full text of DOI:10.1134/S107036320911005X

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 11, pp. 2304–2316. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © V.M. Fomin, A.E. Shirokov, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79, No. 11, pp. 1782–1795.
Specific Features of Oxidation
of Ferrocenylacetic Acid with Molecular Oxygen
in the Absence and in the Presence of Brønsted Acids
V. M. Fomin and A. E. Shirokov
Lobachevskii Nizhnii Novgorod State University,
ul. Gagarina 23, Nizhnii Novgorod, 603950 Russia
e-mail: niih325@bk.ru
Received February 9, 2009
Abstract—Comparative analysis of the specific features of autooxidation of ferrocenylacetic acid
(FcCH2COOH) in organic solvents at 30–50°C in the absence and in the presence of trifluoroacetic acid
(processes 1 and 2 respectively) was carried out. It was shown that both reactions proceed as a sequence of two
macrostages, the molecular and the chain radical oxidation of the metal complex. Introduction of acid (HX) in
the reaction mixture leads to a significant increase in the rate of the process, in the amount of oxygen per one
mole of metal complex absorbed by the reaction mixture, and to the change in the yields of main reaction
products like hydroxymethylferrocene, formylferrocene, ferrocenylpyruvic acid, and CO2. On the basis of
results of the investigation performed, the kinetic and thermodynamic analysis of primary reactions of the
process probable mechanisms of both macrostages in both processes were suggested. The significant effect of
approach and orientation on the rate of the molecular oxidation of complex as the bifunctional reagent was
noted. An assumption was made that the acid takes place in the molecular oxidation of FcCH2COOH according
to two alternative mechanisms differing by the way of its coordination with O2 and the metal complex in the
prereactional intermediates. The oxidative transformation of these intermediates leads to the generation of
radicals of different nature, Fc+·CH2C(O)OO· and HO2· which initiate the chain radical oxidation of the metal
complex.
DOI: 10.1134/S107036320911005X
In this connection the ferrocenylacetic acid (I) is
one of the most interesting objects for investigation
because it exhibits the abnormally high reactivity in
relation to oxygen as compared to the model
ferrocene–carboxylic acid system (pKa ≈ 5). Com-
pound I is easily oxidized at 20–50°C in the absence of
any acids [3–5]. On the basis of the results of kinetic
studies and the data on the composition of the reaction
products a probable mechanism of oxidation of
compound I was suggested [5] including two pathways
(Scheme 1).
The interest to investigation of autooxidation
processes of ferrocene derivatives with various func-
tional groups is caused by the fact that many of them
are bifunctional reagents having the electron-donor
reaction site localized on the metal atom and the
electron-acceptor one, the Lewis or Brønsted center,
localized on the substituent. These sites may take part
in conjugation with one another through a molecule of
oxygen (or some other oxidant), and that should
initiate the oxidation of substrate at the metal atom.
From this point of view the ferrocene derivatives may
be regarded as models of enzymatic systems in the
processes of oxidation. Effects of approach and
orientation are characteristic of such reactions. These
effects lead to significant decrease in the activation
free energy of the process (up to 50 kJ mol–1) due to
the gain in activation entropy as compared to the
reacting systems where the analogous participating
reaction sites are present in different molecules [1, 2].
The formation of the internal ferricinium salt
testifies in favor of the pathway a significantly con-
tribution in the total oxidation process of compound I.
The existence of the pathway b was deduced from the
formation of CO2 (yield about 0.2–0.25 mol/mol of the
consumed compound I) and the products of the
oxidative degradation of the ferricinium ion. The
internal ferricinium salt is stable against heating up to
2304

SPECIFIC FEATURES OF OXIDATION OF FERROCENYLACETIC ACID
2305
(1)
RCOOH + RO2• → ROOH + RCOO•.
Scheme 1.
CH2COOH
CH2COO
K
If the pathway a is energetically more favorable
than the pathway b, and reaction (1) is more favorable
than reaction (2) of acid decarboxylation under the
+ O2
Fe
Fe
O2
H
A
–
action of O2• , the mechanism of molecular oxidation of
CH2COO−
compound I must include only the pathway a
described by Eq. (1.1).
kа
Fe+
Fe+
+ HO2
(1.1)
(1.2)
RCOOH + O2•– → RC(O)O• + HO2–.
(2)
A
CH2COO
OOH−
kb
The decarboxylation of the complex in this case
must be considered as the secondary process. It
follows from Scheme (2) that this process must be
undoubtedly the radical chain one. This conclusion
produces logically at least two questions concerning
the mechanism of oxidation of compound I which
were not considered in [4, 5]. Firstly, what is the
mechanism of the radical chain oxidation of compound
I, and what kind of products are formed? Secondly, if
the presence of a substituent containing the carboxy
group (pKa ≈ 5 [8]) plays the determining role in the
reaction of the metal complex with oxygen, what kind
of influence will be exerted by strong Brønsted acids
(HX) such as HClO4 II or CF3COOH III upon the
reactivity of this complex and the mechanism of its
oxidation?
Fe(O)OH + CO2
+ organic products
250°C [3] and cannot be the source of CO2• RCOO–
anions are usually decarboxylated under the anodic
oxidation [6]. Therefore the suggestion that the carbon
dioxide is the product of oxidative decarboxylation of
compound I seems quite logical. According to the
Scheme (1) it is suggested that this reaction proceeds
–
under the action of superoxide oxygen O2• formed by
electron transfer on the O2 molecule. Being the radical
anion this particle is capable of abstracting not only
proton, but also the hydrogen atom from the carboxy
group of the substituent. The first process (pathway a)
is doubtless, but the oxidative decarboxylation of
–
compound I under the action of O2• is not so evident
This study deals with solving of these problems.
without the evaluation of the energy of the process.
Besides, the oxidation of compound I according to the
pathway a leads to formation alongside the internal
ferricinium salt of HO2• peroxide radical which not
only can take part in the reaction of oxidative
decarboxylation of the starting compound [7], but also
can initiate this process, for example, according to the
Scheme (2).
To make a conclusion on the possibility of com-
pound I decarboxylation under the action of O2–· it is
necessary to compare the energies of the reactions (1)
and (2) taking that complex I = RCOOH. For the
calculation of standard enthalpies ΔrH10 and ΔrH20 of
these reactions relationships (3) and (4) can be used.
ΔrH10 = D(RCOO–H) – D(HOO–H),
ΔrH20 = D(RCOO–H) – D(H–O),_
(3)
(4)
Scheme 2.
where Di is the energy of the corresponding O–H
bonds.
I
I + O2 → HO2• → C5H5FeC5H4C•HCOOH,
(2.1)
R¯•
As known, D(RCOO–H) bond energy in the
carboxylic acids containing no strong electron-acceptor
substituents in the radical R varies within the range
435–448 kJ mol–1 [9]. For compound I it may be ac-
cepted as equal to the O–H bond energy in phenyl-
acetic acid, 448 kJ mol–1 which we shall regard as the
model analog of ligand π-C5H4CH2COOH in the metal
complex. D(ROO–H) bond energy equals 365 kJ mol–1
[10]. D(H–O2–) bond energy can be calculated from
Eq. (5) because D(H–O2–) = –ΔrH50.
R¯• + O2 → R¯O2• ,
R¯O2• + I → ROOH + C5H5FeC5H4CH2COO•
(2.2)
(2.3)
C5H5FeC5H4CH2COO• → C5H5FeC5H4C•H2 + CO2. (2.4)
R¯•1
In general, reaction (2.3) may be written as Eq. (1).
Its validity was shown on a series of examples in the
course of studies of the radical chain oxidation of
organic compounds [7].
O2–• + H• → HO2–.
(5)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

2306
FOMIN, SHIROKOV
Reaction enthalpy ΔrH50 can be found from the well-
O–H bond in the acid, and to the possibility of syn-
chronic transfer of hydrogen atom in the
RCOOH····OOR hydrogen complex from the acid to
RO2· radical, resulting in the decrease in the activation
energy of the process. Considering the above reaction (1)
for phenylacetic acid may be represented as follows:
known thermochemical relationship (6).
ΔrHi0 = ΣvjΔfHj0 – ΣviΔfHi0.
(6)
Here ΔfH0i,j are standard enthalpies of formation of the
reaction products (j) and the starting substances (i).
–
Values of standard enthalpies of formation of O2• , of
PhCH2COOH + RO2• → PhCH2• + CO2 + ROOH.
(1')
HO2–, and of H· are –43.23 kJ mol–1 [11], –102.03 kJ mol–1
[12, 13], and 218 kJ mol–1 [13] respectively.
The standard enthalpy value for this reaction
obtained from relationship (6) or taking into account
the data [9] is –15.3 kJ mol–1 (ΔfH0 values for the acid
It gives the value of D(H–O2–) bond energy
276.8 kJ mol–1. From the relationships (3) and (4) it
follows that ΔrH10 = 83 kJ mol–1, ΔrH20 is 171.2 kJ mol–1.
·
and PhCH2 are taken from [9]). The value of Gibbs
free energy ΔrG01' of the reaction considering a positive
ΔtS01' value will be still lower than ΔfH01' explaining the
possibility of the reaction.
Note that while calculating D(H–O2–) the value
ΔfH0(HO2–) was found from the relationship (7)
ΔfH0(HO2–) = ΔfH0(HO2•) + EA(HO2•),
(7)
The variation of entropy in the decomposition of
RCOO· will most probably be practically independent
of the nature of the R radical. It permitted to use the
entropy value for the reaction of decomposition
of CH3COO· ΔfSp0 106.1 J mol–1 K–1 [S0(CO2)
213.6 kJ mol–1 K–1, S0(CH3·) 194.3 kJ mol–1 K–1 [13],
S0(CH3COO·) 301.8 kJ mol–1 K–1; the last value was
calculated using the G03W2 software] for calculation
of ΔrG01' which proved to be equal –46.9 kJ mol–1.
Results of these calculations may be extended also to
the process of decarboxylation of compound I.
·
where EA(HO2·) is the affinity of HO2 radical to an
electron.
Reported data on this value vary in a wide range
(3.04 eV [14], 1.88 eV [15], 1.078 eV [12]. It may
bring significant difference in the results of the energy
effect calculation of the reactions and in the
conclusions following from them. The above-given
ΔfH0(HO2–) value –102.03 kJ mol–1 relates to the EA
(HO2·) value 1.078 eV reported recently. If EA(HO2·)
value 3.04 eV1 is considered, D(H–O2–) value occurs to
be higher than D(RCOO–H) which certainly is not the
case. The contribution of the entropic increment in the
standard Gibbs energy of the reactions (1) and (2) is
most probably small. It is much lower than ΔrH10 and
ΔrH20 values. Therefore these characteristics of
reactions can be considered as thermodynamic criteria
of their occurrence.
Comparison of ΔrH10 and ΔrH20 shows that though
the reaction (1) is by 87.2 kJ mol–1 more favorable
than the reaction (2), its proceeding is hampered by
thermodynamic reasons. Nevertheless, decarboxylation
of carboxylic acids takes place under the action of
peroxy radicals. It is caused firstly by the high
decomposition rate of the RC(O)O· radicals (rate
constant of decomposition of PhCH2C(O)O· at 298 K
is 7.84×109 s–1, reaction enthalpy –98.3 kJ mol–1 [9])
what shifts the equilibrium of the reaction (1) to the
right and makes it more thermodynamically favorable.
Secondly, the reaction mechanism includes the stage of
formation of a strong hydrogen bond between RCOOH
and RO2· [7]. It leads to the decrease in the energy of
Enthalpy of reaction (2) for PhCH2COOH even
considering the decomposition of PhCH2C(O)O·
radical is a large positive value equal 72.9 kJ mol–1
which is not compensated by the increase in the
reaction entropy (298ΔrGp0 31.6 kJ mol–1). Hence, the
extrapolation to compound I of the above results of
thermochemical calculations fot the decarboxylation of
–
the phenylacetic acid under the action of O2• and RO2·
radicals makes it clear that the oxidative decarboxyla-
tion of this complex is based on the molecular
oxidation according to the pathway a leading to
generation of HO2· peroxide radicals. The conclusion
that the pathway a is the only route of molecular
oxidation of compound I may be substantiated also by
another procedure, namely, by comparison of the
energies of the pathways a and b. In this case model
reactions look like the following.
PhCH2COOH + O2•– → PhCH2COO– + HO2•, ΔrH80, (8)
PhCH2COOH + O2•– → PhCH2COO• + HO2–, ΔrH90. (9)
2
Authors express their gratitude to Doctor of Chemical Sciences
S.K. Ignatov for the performed calculations, and to the
administration of Lobachevskii Nizhnii Novgorod State
University for the offered software.
1 The value of [14] as a whole is not diminished by this note.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

SPECIFIC FEATURES OF OXIDATION OF FERROCENYLACETIC ACID
2307
Equation (10) of the resulting reaction is obtained
by subtraction of Eq. (9) from (8).
probably true for the same reactions in solutions. In the
aprotic solvents with low polarity and permittivity
significant difference in the values of energy effects of
the reactions under consideration from that obtained
for the gas phase can hardly be expected. The increase
in the polarity and permittivity of solvents favorable
for proceeding of the electron and proton transfer
reactions will lead to still more contrast in the energy
characteristics of the pathways a and b of the
compound I oxidation.
Radical HO2· can initiate the radical chain oxidation
of the metal complex. With the purpose to confirm this
statement we carried out more detailed analysis of the
products of oxidation of compound I than it had been
performed in [5]. The aim of these studies was the
establishing of the presence of the compounds which
together with CO2 unambiguously show that oxidation
of this metal complex may proceed not only by the
molecular, but also by the radical chain mechanism.
PhCH2COO• + HO2– → PhCH2COO– + HO2•, ΔrH010. (10)
Reaction enthalpy ΔrH010 is equal to the difference
in enthalpies ΔrH80–ΔrH90. This difference may be taken
as equal to the difference in enthalpies ΔrHa0–ΔrHb0.
Using relationship (6) it can be shown that ΔrH0
=
10
ΔrHa0 – ΔrHb0 –228 kJ mol–1 {ΔfH0(PhCH2COO–) =
–88 kJ mol–1 [9], ΔfH0(PhCH2COO–) = –420 kJ mol–1
[16]}. As the reaction (10) results in the electron
transfer between the reagents it must be accepted
according to [17] that the the variation in entropy of
this reaction ΔrS010 ~ 0. From that it follows that ΔrH010 =
ΔrG010 = ΔrGa0–ΔrGb0. Therefore it is possible to regard
ΔrH010 value as the thermodynamic criterion of the
proceeding of reaction (10). This large negative value
shows that among the pathways a, b presented in the
Scheme 1 the first one is significantly more favorable
thermodynamically as compared to the second route.
But final conclusion can be made after consideration of
the high rate of decomposition of PhCH2COO· radical,
of the high exothermic effect, and of the positive ΔrSp0
value for this process. In this case Eqs. (9) and (10) are
transformed into Eqs. (9') and (10').
It was found that together with the previously found
oxidation products of compound I also neutral ferro-
cene derivatives formed, the main products being
hydroxymethylferrocene IV and formylferrocene V.
Yields of compounds IV, V are 0.28 and 0.11 mol per
mol of consumed metal complex respectively. Among
the minor products ferrocenylpyruvic acid VI, ferro-
cenecarboxylic acid VII, and CO were found. The
products of oxidative degradation of ferricinium ion con-
tained also cyclopentadiene and cyclopentadienone dimer.
PhCH2COOH + O2–• → PhCH2• + CO2 + HO2–, ΔrH09',
(9')
PhCH2• + CO2 + HO2– → PhCH2COO– + HO2•, ΔrH010'. (10')
The pathway b transforms to the pathway b'
analogously to the reaction (9). Then ΔrH010' = ΔrHa0 –
ΔrH0b' = ΔrH010 + 98.3 kJ mol–1 = –129.7 kJ mol–1.
Radical chain oxidation of compound I was
confirmed by deceleration of the process on the
addition of o-phenylenediamine known as the inhibitor
of the radical chain reactions (Fig. 1) and at the use of
ethanol instead of dioxane as a solvent. But contrary to
the example of compound IV whose oxidation is
almost completely suppressed by the action of the
above-mentioned substances [18], the total cessation of
compound I oxidation does not occur because of the
noticeable role of the molecular pathway of oxidation
of the metal complex. Rate of the CO2 accumulation in
alcohols is also lower than in dioxane (Fig. 2).
As compared to the reaction (9) the entropy of the
reaction (9') increases by the value ΔrSp0 = 106.1 J mol–1 K–1.
The entropy of reaction (10') decreases by the same
value as compared to the entropy of reaction (10)
where ΔrS010 = 0. It provides the opportunity to
calculate the free Gibbs energy of reaction (10')
according to the equation: ΔrG010' = ΔrGa0 – ΔrG0b' =
–129300 – 298(–106.1) = –98.1 kJ mol–1.
The knowledge of ΔrGa0–ΔrGb0 value permits the
calculation of the ratio of the formal equilibrium
constants of the pathways a and b' Ka/Kb' for the
molecular oxidation of compound I which proved to be
equal 1.67×1017. This result unambiguously shows that
only one pathway of molecular oxidation of compound
I leading to the formation of the internal ferricinium
Formation of oxoacid VI and hydroxymethyl-
ferrocene IV in the oxidation of compound I shows
that its radical chain oxidation proceeds with the
simultaneous participation of two reaction centers, the
methylene and the carboxy groups of the substituent.
Oxidation of the methylene group initiated by peroxy
radicals is a process quite natural from the
thermodynamic and the kinetic point of view because
·
salt and HO2 radical takes place.
Though the calculations presented correspond to
the gas phase, the conclusions made will be most
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

2308
3.5
FOMIN, SHIROKOV
N(O2)
N(CO2)
3.5
1.0
3
3.0
2.5
2.0
1.5
3
3.0
2.5
2.0
1.5
1.0
0.5
0.8
0.6
0.4
4
1
5
6
1.0
1
0.2
4
2
0.5
0.0
2
0.0
0.0
0
10
20
30
40
50
60 t, min
0
5
10
15
20
t, min
Fig. 2. Kinetic curves of oxidation of (1–3) compound I
and (4–6) accumulation of CO2 in (1–5) dioxane and (6) in
methanol in (1, 5, 6) the absence of acids and (2) in the
presence of acid II and (3, 4) acid III (3,4). C0I 0.01 M, C0III
0.03 M, C0II 0.1 M, P(O2) 0.42×105 Pa, T 50°C.
Fig. 1. Effect of o-phenylenediamine (In) on the oxidation
of compound I (1, 2) in the absence of acid III and (3, 4) in
the presence of it. CI0 0.005 M, C0III 0.05 M, C0In(2) 1×
10–4 M, C0In(4) 2.5×10–4 M, P(O2) 0.42×105 Pa, T 50°C.
it is known that the C–H bond energy in alkylaromatic
hydrocarbons is 50–60 kJ mol–1 lower than in the
saturated ones [10, 14]. Because of that the C–H bond
energy in the methylene group of compound I can be
without a large error to be taken at ~330 kJ mol–1. In
this case the enthalpy of hydrogen atom abstracting
from it with RO2· radical must be equal to –35 kJ mol–1
because the activation energy of this process does not
exceed 42 kJ mol–1 [10]. The paricipation of COOH
group in the radical chain oxidation of compound I
besides the above-presented reasons is confirmed by
some others. First of all it is the presence of compound
IV in the reaction products because its formation
cannot be explained without the oxidative decar-
boxylation of compound I. From the kinetic point of
view the hydrogen transfer in the COOH····OOR
hydrogen complex whose equilibrium concentration is
established immediately can be considered as the
monomolecular reaction proceeding with the sufficient
gain in the activation entropy as compared to
bimolecular reaction of hydrogen abstraction from
methylene group with RO2· radicals. It must lead to
considerable equalization of the activation free energy
of the abstraction of hydrogen atom from CH2 and
COOH groups. The activation energy in the first case
will be undoubtedly lower than in the second one.
Besides, the lifetime of R¯1C(O)O· radical is about
1.27×10–10 s. Since it can exist only in the cage of
solvent in the moment of its formation, the radical
leaving the cage is R¯1·. It quickly reacts with oxygen
[k ~ (2–5)×109 l mol–1 s–1] to give R¯1O2· radical [19]
which produces compound IV.
On the basis of the above data the probable
mechanism of the radical chain oxidation of compound
I uncomplicated by the degenerate branching of chains
and including only its main stages can be described by
Scheme 3.
Despite certain specific differences between the classic
scheme of the radical chain oxidation of hydrocarbons
RH [7] and this scheme of compound I oxidation they
are in general analogous. Reactions (3.0) are the stages
of generation of the R¯· radical starting the chain.
Reactions (3.1)–(3.6) describe the propagation of the
chain, and the reactions (3.7), (3.8), its termination.
The termination of the chain by the reaction of the
metal complex with peroxy radical is confirmed in [19]
by an example of oxidation of compound IV. Reac-
tions (3.9)–(3.15) describe the main pathways of
transformation of hydroperoxides ROOH and R1OOH
and the radical-ion salts Fc+·OOR¯– and Fc+·OOR¯1–
leading to formation of the established metal complex
products of the radical chain oxidation of compound I.
It is seen from the presented scheme that CO2
formation may proceed not only by the oxidative
decarboxylation of the starting metal complex, but also
in the course of oxidation of the methylene group.
Transformation of ROOH hydroperoxide according to
the reaction (3.10) leading to formation of compound
V and carbonic acid is similar to the transformation of
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

SPECIFIC FEATURES OF OXIDATION OF FERROCENYLACETIC ACID
2309
(11)
OOH
CH
O
C
Scheme 3.
CH3CHO + CH3C(O)OH.
CH3
CH3
I + O2 → C5H5Fe+C5H4CH2C(O)O– + HO2•
(3.0)
(3.1)
I + HO2• → H2O2 + C5H5FeC5H4C•HC(O)OH
Compound V is formed in three reactions, (3.10),
(3.11), and (3.14). Under mild conditions at low
temperature reaction (3.11) is considerably more
favorable thermodynamically than the hemolytic
decomposition of hydroperoxide R¯1OOH requiring
about 165 kJ mol–1 [19]. In the course of
transformation of R1OOH according to the reaction
(3.11) the cleavage of one O–O bond [D(O–O) 165 kJ
mol–1] and of one C–H bond [D(C–H) ~330 kJ mol–1)
takes place. Then one H–O bond in water {D(H–O)
498 kJ mol–1 [14]} and one π-bond in C=O group
{D(Cπ–O) ~290 kJ mol–1 [20]} are formed. Total gain
in energy is ~–273 kJ mol–1. Besides, this reaction
most probably proceeds according to synchronic
mechanism and should have low activation energy. It
is not by chance that in the course of the radical chain
oxidation of ethylbenzene the yield of acetophenone is
6.5 times higher than that of methylphenylcarbinol
[21]. Note that these speculations can be completely
applied also to reaction (11). Evaluation of the
enthalpy variation on the basis of energies of the
ruptured and forming bonds leads to the value about
–240 kJ mol–1. Standard enthalpy of the reaction (3.10)
is undoubtedly less negative because of low stability of
H2CO3. But considering that the reaction proceeds with
the significant increase in entropy which for such
processes may reach 120–189 J mol–1 K–1 [1], the
Gibbs free energy in this case will have the large
negative value. Synchronic reaction mechanism should
also provide low activation energy. Together with
thermodynamic factor it will favor the high rate of the
process.
Rearrangements of the radical ion salts Fc+·OOR¯–
and Fc+·OOR¯1– leading to formation of compounds V,
VI are characteristic of the peroxide metal complexes
LnM+(OOCHR1R2)– (LnM is the transition metal
complex) when the carbon atom bound to the peroxy
group bears a hydrogen atom [22]. Compound VI can
be formed also by transformation of peroxide R¯OOH
according to the equation (3.9). Low yield of this
product can be explained by the higher rate of
transformation of the above-mentioned peroxide by the
reaction (3.10) and also by the extremely high
reactivity of carbonyl group in it in relation to the
reactions characteristic of ketones, for example, with
hydroperoxides [23] and water [6].
R¯•
R¯• + O2 → R¯O2•
k3.2
R¯OOH + R¯•
(3.2)
(3.3)
R¯O2• + I
k3.3
R¯OOH + C5H5FeC5H4CH•2 + CO2
R¯1•
R¯1• + O2 → R¯1O2•
(3.4)
(3.5)
k3.5
R¯1OOH + R¯•
R¯1O2• + I
k3.6
R¯1OOH + R¯1• + CO2
(3.6)
(3.7)
k3.7
R¯O•2 + I
R¯1O•2 + I
[C5H5Fe+C5H4C(O)OH]OOR¯–
Fe+•OOR¯–
k3.8
[C5H5Fe+C5H4C(O)OH]OOR¯–1
Fe+•OOR¯–1
(3.8)
(3.9)
H2O + C5H5FeC5H4–C(O)–C(O)OH
VI
R¯OOH
C5H5FeC5H4–CHO + H2CO3 → H2O + CO2
(3.10)
V
(3.11)
R¯1OOH → C5H5FeC5H4–CHO + H2O
V
I + R¯1OOH → C5H5Fe+C5H4CH2COO– + R¯1O• H2O
(3.12)
(3.13)
SH
–S•
R¯1O•
Fc+
R¯1OH
C5H4FeC5H5
H
−
O
−
C
Fc+ OOR−
O
H
Fc+ OOH− + V
(3.14)
(3.15)
H
C5H4FeC5H5
−
O
C
−
−
+
1
Fc OOR
Fc+
O
COOH
Fc+ OH− + VI
hydroperoxide CH3–CH(OOH)–C(O)–CH3 formed in
the course of the oxidation of methyl ethyl ketone [7].
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

2310
FOMIN, SHIROKOV
As it follows from the above-presented scheme, the
1 mol of compound I [N(O2) ~ 1.3] show that the
contributions of rates of molecular (ν0) and the radical
chain (νr) pathways of oxidation of metal complex in
the total rate of the process (ν) are comparable. Due to
that the overall rate can be presented as sum of
oxidation rates of compound I along each pathway.
formation of compound IV is caused by the oxidative
decarboxylation of compound I. It is connected not
with the homolysis of peroxide bond in R¯1OOH, but
with the reaction of this hydroperoxide with metal
complex according to Eq. (3.12). Characteristic feature
of this reaction is the possibility of participation of the
substituent carboxy group in oxidation as it is shown
below:
v = v0 + vr.
(13)
It was shown previously that the experimental rate
of the process is described by Eq. (14).
O
CH2C
v = keff[I][O2].
(14)
I + R1OOH
Fe
O
O
H
H
Then
O
v = v0 + vr = keff[I][O2].
(15)
R1
For ν0 such dependence on the concentration of
CH2COO−
reagents is evident
Fe+
+ H2O + R1O
(12)
v0 = kaK[I][O2] = k0[I][O2],
(16)
where k0 = kaK.
The coordination of compound I with R¯OOH by the
iron atom may take place by means of interaction of
the metal complex HOMO localized on the metal atom
For the fulfillment of relationship (15) it is
necessary that the analogous dependence of the
reaction rate on the starting concentrations of reagents
must be fulfilled also for νr. According to [7] the rate
of the radical chain oxidation of hydrocarbons RH is
determined by the rate of the reaction of chain
propagation.
(dxy or dx –y [24]) with the vacant σ*-orbital of the
2
2
peroxide bond.
In such mechanism of oxidation of metal complex
with hydroperoxide as well as in its reaction with
oxygen it plays the role of bifunctional reagent. It is
the necessary condition for exhibiting the effect of
approach and orientation that significantly accelerates
the oxidation. As is known, homolytic decay of
R¯1OOH must lead to the degenerate branching of
chains. It should cause autoacceleration of oxidation of
com-pound I with time. The character of the kinetic
curves of oxygen consumption with the reaction
mixture (Fig. 2) disagrees with that.
kr
RO•2 + RH
ROOH + R•.
According to Scheme 3 each of the peroxide radical
formed R¯O2· and R¯1O2· can enter the analogous reaction
with the molecule of compound I by two pathways
described by the reactions (3.2), (3.3), and (3.5), (3.6)
respectively. For the equation of the rate of compound
I oxidation by the radical chain mechanism con-
sidering all the reactions of chain propagation and
termination with the participation of R¯O2· and R¯1O2· the
following admissions should be accepted.
In addition to the mechanism of the reaction (12) it
should be noted that under the analogous conditions
the oxidation of ferrocene with hydroperoxides [H2O2
or (CH3)3COOH] proceeds extremely slow.
(1) Quasistationary concentration of both peroxide
radicals is achieved quickly due to the high rate of
radical generation (ν0) [19].
Analogous reaction of compound I with R¯OOH is
hindered evidently by steric reasons. For the reaction
of this complex with R¯O2· described by Eq. (3.7) the
steric factor is significantly less important because of
the another orientation of peroxide radical in the attack
of metal atom. Formation of the internal ferricinium
salt, on the one side, and of compounds IV, V and
CO2, on the other, in comparable amounts, and also a
weak consumption of oxygen for the oxidation of
(2) In the quasistationary regime the rates of chain
propagation involving R¯O2· and R¯1O2· are equal.
− .
ν(RO2)
−
.
(17)
(18)
= ν(R1O2),
− .
−
.
ν(RO )
= (k3.2 + k3.3)[RO2][I],
2
−
.
−
.
ν(R1O2)
(19)
= (k3.5 + k3.6)[R1O2][I].
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

SPECIFIC FEATURES OF OXIDATION OF FERROCENYLACETIC ACID
2311
the establishment of the effect of acid additives of
different strength on the rate of oxidation of metal
complex, its kinetic rules and the mechanism of the
process presented the doubtless interest.
From that follows:
− .
−
.
ν = 2ν(RO ) ν(R O ).
=
(20)
r
2
1 2
(3) Rates of the chain termination involving R¯O2·
and R¯1O2· slightly differ. Though the reaction of R¯1O2·
radical with compound I is more favorable by steric
reasons, the presence of carboxy group exhibiting
strong electron-acceptor properties in R¯1O2· radical
increases its activity in the one-electron transfer reactions.
It was shown previously [4] that the addition of
benzoic acid (C0HX/C10 = 8) with pKa close to that of
compound I does not affect the rate of its oxidation
because of the stronger influence of carboxy group of
substituent on the reactivity of metal complex due to
effects of the approach and orientation. Additives of
strong acids like HClO4 (II) and CF3COOH (III)
exhibit different effects. It turned out that in presence
of compound II complex I lost its ability to get
oxidized with the noticeable rate for a long time.
v3.7 = v3.8,
(21)
(22)
(23)
v
3.7 = k3.7[R¯O2•][I],
v
3.8 = k3.8[R¯1O2•][I].
It follows that the total rate of chain termination (νt)
is equal to:
It is sufficient to state that keeping the compound I
solution in dioxane in the presence of acid II
(C0HX/C10 = 10) in the atmosphere of oxygen for 10 h at
50°C yields only 0.02 mol of CO2 per 1 mol of the
starting complex. The addition of acid to the solution
of compound I in dioxane causes an immediate change
in its color from yellow to green. Electron absorption
spectrum of the solution contains the bands at λmax 450
and 620 nm (Fig. 2) corresponding to α-ferrocenyl-
carbenium ion [25]. The formation of the latter may be
due to the protonation of compound I proceeding with
the formation of ferrocenylacetylium cation. It quickly
converts into more stable α-ferrocenylcarbenium ion
by the elimination of CO [26]. The oxidation of the
latter carbocation is very specific and slow.
vt = 2v3.7 = 2v3.8.
(24)
(4) Rate of radical generation is equal to the total
rate of chain termination.
v0 = vt.
(25)
(5) From the relationships (22)–(25) the expression
for the concentration of R¯O2· and R¯1O2· radicals can be
found. Then using the relationships (18)–(20) the equa-
tion for the rate of oxidation of compound I (νr) can be
written as follows:
vr = 2v(R¯O2·) = [(k3.5 + k3.6)k0/k3.7][I][O2].
(26)
The obtained expression for νr completely corres-
ponds to the relationship (15) which in this case
acquires the following shape:
C5H5FeC5H4CH2COOH + 2HX
→ C5H5FeC5H4CH2C+O + H3O+ + 2X–.
(29)
v = v0 + vr = [k0 + (k3.2 + k3.3)k0/k3.7][I][O2]
In the presence of acid III the formation of
ferrocenylacetylium cation does not take place (Fig. 3)
but a strong acceleration of the compound I oxidation
and the simultaneous increase in N(O2) to 4–5 are
observed. These effects are demonstrated by Fig. 1.
The results obtained show that significant increase
occurs in the role of the radical chain pathway in the
total process of compound I oxidation. Some other
facts also support this statement. Firstly, oxidation of
compound I is decelerated by additive of o-
phenylenediamine (Fig. 1) known as the inhibitor of
the radical chain reactions. The effect of deceleration
of oxidation of compound I by the additives of this
inhibitor in the absence of acid is significantly less.
Secondly, the oxidation of compound I is decelerated
by using ethanol instead of dioxane as a solvent
(Fig. 4) which can inhibit oxidation by binding the
starting metal complex and the intermediates, first of
= [1 + (k3.2 + k3.3)/k3.7]k0[I][O2] = keff[I][O2],
(27)
k
eff = k0[1 + (k3.2 + k3.3)/k3.7] = kaK[1 + (k3.2 + k3.3)/k3.7]. (28)
Hence, the assumed mechanism of oxidation of
compound I including the molecular and the radical
chain pathways corresponds to the experimentally
established kinetic rule describing the course of this
reaction. The authors realize that the admissions
accepted are quite approximate, but such approach to
the analysis of mechanism of the radical chain oxida-
tion of organic compounds (in our case of compound
I) never used before leads to the results completely
corresponding to the experimental data.
As it was mentioned already, the generation of
radicals in the molecular oxidation of compound I
proceeds with the direct participation of the carboxy
group of substituent in this process. In this connection
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

2312
FOMIN, SHIROKOV
A
0.596
0.400
0.200
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
5
4
1
2
3
2
0
5
10
15
20
t, min
3
Fig. 4. Effect of the nature of solvent on the oxidation of
compound I (1, 2) in the absence of the acid III and
(3–5) in the presence of it: (1, 4) dioxane, (2, 3) ethanol,
(5) methyl metacrylate. CI0 0.01 M, C0III 0.05 M; P(O2)
0.42×105 Pa, T 50°C.
1
0.000
–0.048
400
500
600
λ, nm
700 750
Fig. 3. Electron absorption spectrum of the solution of
compound I in dioxane under argon: (1) in the absence of
acids, (2) in the presence of the acid II, (3) in the presence
of the acid III. CI0 0.005 M, C0II 0.5 M, C0III 0.5 M.
the first power. It follows from the fact of the linear
increase in the initial rate W0 with the increase in
3
concentration of each of the above-mentioned
reagents. It is characteristic that the dependence
W0–f(CHX) does not pass through the origin indicating
that even in this case compound I participates in the
bimolecular oxidation, but its contribution in the total
oxidative process is much smaller than the con-
tribution of the radical chain pathway. As it was shown
above, in the absence of HX these contributions are
practically comparable.
all R¯O2· and R¯1O2· in the stable hydrogen complexes [7].
Finally, the oxidation of compound I in methyl
metacrylate solution causes the polymerization of the
latter. Analogous effect we established in the course of
the radical chain oxidation of compound IV in methyl
metacrylate [18]. It is characteristic that N(O2) value in
the oxidation of compounds I, IV in methyl meta-
crylate is significantly higher than in the oxidation in
dioxane. That means that oxygen is included in the
form of labile peroxide group in the composition of the
polymer formed. Considering the significant effect of
acid III on the rate of oxidation of compound I and
N(O2) value it presented the doubtless interest to
compare kinetic rules and the composition of the
products of oxidation of metal complex in the absence
and in the presence of this acid.
The comparison of composition of the oxidation
products of compound I in the absence of the acid III
(process 1) and in its presence (process 2) showed that
on the whole they were analogous, but a significant
difference in the yields existed. In this respect the most
demonstrative are the variations in the yields of
compounds IV, V, and CO2 as illustrated by the data
from the table.
Besides, in going from the process 1 to the process
2 [N(O2) = 1.5] a significant decrease in the yield of
compound VII and the increase in the yield of
compound VI are observed. At N(O2) ≥ 4 compounds
IV–II are absent.
Results of investigation of the kinetic rules of
compound I oxidation in the presence of acid III are
shown in Fig. 5 from which it follows that for the
initial rate of the process the reaction order is equal to
one with respect to the initial concentration of
compound I and oxygen [P(O2)]. At the same time the
kinetic equation includes the concentration of acid in
3 Symbol W is used for the definition of experimental data.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

SPECIFIC FEATURES OF OXIDATION OF FERROCENYLACETIC ACID
2313
Experimental data presented in the table can be
explained proceeding from the assumed scheme of the
radical chain oxidation of compound I.
18.0
16.0
14.0
12.0
10.0
8.0
2
The main reason of the increase in CO2 yield in the
oxidation of compound I in the presence of the acid
III, as well as the yield of the compound VI, is the
preferred oxidation of the metal complex under these
conditions along the radical chain mechanism. Effect
of additives of acid III on the ratio of the yields of
compounds IV, V in the processes (1) and (2) is
caused by its effect on the direction of transformations
of the formed peroxides R¯OOH and R¯1OOH [7]. In the
absence of HX the hydroperoxide R¯1OOH evidently
very quickly transforms by Eq. (3.11), and only its
insignificant part enters reaction (3.12) with compound
I leading to the formation of R¯1O· radical and further of
compound IV. It is known that the acids catalyze such
direction of decomposition of secondary hydroper-
oxides [7]. Acid III must also catalyze the
transformation of R¯OOH to α-ketoacid VI according to
Eq. (3.9), but it cannot be excluded that the acid also
catalyzes another pathway of the hydroperoxide decay
leading to the formation of compound V and the labile
carbonic acid [Eq. (3.10)]. As is known, strong acids
favor the decomposition of carbonic acid. Compound
VII is the product of oxidation of compound V. In the
absence of strong acids it is stable to oxygen, but in the
presence of acid it is capable of oxidation. The absence
of products IV–VII in the process (2) when N(O2) ≥ 4
arises from their acid-stimulated oxidation.
3
6.0
4.0
1
2.0
0.0
0
0.001 0.002 0.003 0.004 0.005 0.006
СI, M
0
0
0.01 0.02 0.03
0.04 0.05 0.06
СIII, M
0.1 0.2 0.3 0.4 0.5 0.6 0.7
P(O2)×10–5, Pa
Fig. 5. Dependences of the initial oxidation rate of
compound I (1) on its concentration, (2) concentration of
acid III and (3) on oxygen pressure on dioxane at T 50°C.
(1) C0III 0.01 mol l–1, P0 0.41×105 Pa, (2) C0I 0.01 mol l–1, P0
0.41×105 Pa, and (3) C0I 0.01 mol l–1, C0III 0.01 mol l–1.
The role of the substituent in this process is limited
only to the keeping of oxygen in the coordination
sphere of metal because the protonation of superoxide
oxygen O2–·, formed by the electron transfer from the
iron atom to the molecule of oxygen, by means of acid
III (pKa = 0) will proceed much faster than by the acid
group of compound I (pKa > 5). This process is
significantly more favorable energetically than the
oxidation of compound I in the absence of acid as
follows from the comparison of standard enthalpies of
reactions (30) and (31).
The strong acceleration of compound I oxidation
under the action of the acid III and its preferred course
by the radical chain mechanism under these conditions
suggests the appearance of new, more abundant source
of radicals generated only under the direct participa-
tion of the acid. In the simplest form this participation
can be described by Scheme 4.
Scheme 4.
CH2COO
O2
K1
(4.1)
I + O2
Fe
H
Yield of the reaction products of compound I oxidation
(mol/mol of starting complex), T 50°C
A
Yield of the
CH2COO
Compound IV
Compound V
CO2
K2
product
Process 1а
Process 2b
Process 2c
A + HX
Fe
O2
H
0.28
traces
traces
0.11
0.30
0.24
0.15
0.62
HX
(4.2)
B
traces
CH2COOH
k1
Fe+ X−
a
c
b
+ HO2
Сomplete oxidation of compound I [N(O2) ~1.3]. N(O2) = 1.5.
Complete oxidation of compound I [N(O2) ~ 4].
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

2314
FOMIN, SHIROKOV
CF3COOH + O2–· → CF3COO– + HO2•, ΔrH030,
(30)
As known, the equilibrium (5.1) should be
established immediately, and complex C may be
regarded as the starting compound in the reaction with
oxygen. Formally it may be regarded as the decrease in
the order of the reaction under investigation leading to
the gain in activation entropy. The electrophilicity of
the carbon atom of the carboxy group is confirmed by
the estimation of the electronic density distribution in
the molecule of formic acid. It shows that positive
charge on the carbon atom (+0.401 [28]) is higher than
that on the hydrogen atom of hydroxy group.
PhCH2COOH + O2–· → PhCH2COO– + HO2•, ΔrH031. (31)
The subtraction of Eq. (31) from Eq. (30) gives the
equation of the resulting reaction (32).
CF3COOH + PhCH2COO–
→ CF3COO– + PhCH2COOH, ΔrH032.
(32)
The standard enthalpy of this reaction ΔrH032
=
ΔrH030 – ΔrH031 will characterize the ability of compared
acids to lend the proton to the molecule of superoxide
oxygen. The calculation of the reaction enthalpy ΔrH032
using relationship (6) leads to the value –74 kJ mol–1.
Values of standard enthalpies of formation of reagents
are taken from [27] (CF3COOH) and [16] (CF3COO–
and PhCH2COO–). Since the variation in entropy value
for the reaction (32) may be accepted equal to zero, as
follows from the Eq. (33), the obtained ΔrH032 value
will be equal to ΔrG032 Therefore it may be used as a
thermodynamic criterion for the occurrence of the
reaction (32). ΔrH032 value –74 kJ mol–1 seems sufficient
for considering that Scheme 4 is a really existing process.
Regretfully, the comparison of energies of total
reactions described by Schemes 4 and 5 is impossible
because of the absence of the necessary data on the
enthalpies of formation ΔfH0i not only of the real
reagents, but also of the phenylacetic acid derivatives
used in model calculations.
Nevertheless, from the kinetic point of view the
oxidation of compound I described by Scheme 5 seems
more attractive than the mechanism shown in Scheme 4.
Just in such way of HX coordination with the molecule
of compound I the metal complex can enter the
reactions with oxygen as the bifunctional reagent. This
is the necessary condition for exhibiting the effects of
approach and orientation in the oxidation of compound
I. It may result in the significant gain in the free
activation energy as compared to the process described
by Scheme 4. The bonding of the oxygen molecule
with the electrophilic carbon atom of the substituent
stimulates the electron transfer from the metal atom to
oxygen. In its turn it leads to the increase in polarity of
C–OH bond and in nucleophilicity of the hydroxy
group. The latter in its turn is capable of protonation
by the acid HX coordinated with it. These synchronic
transformations of the triple complex D while moving
along the reaction coordinate result in the formation of
the metal complex peroxide radical [R¯1C(O)O·]+ and
water. For compound I oxidation according to Scheme
4 the effect of approach and orientation is excluded.
The reaction scheme offering the location of O2
molecule in the bridge position between the metal
atom and the hydrogen atom of the carboxy group of
substituent as in the complex A of the Scheme 4 does
not explain the influence of HX in the Scheme 5 on the
rate of the process, because the energy of the reaction
will be the same as in the bimolecular interaction of
compound I with O2 (Scheme 1). It is not excluded
that in the oxidation of compound I in presence of the
acid III mechanism (4) contributes something to the
radicals generation, but the authors given preference to
ΔrS033 = [S0(PhCH2COOH) – S0(PhCH2COO–)]
– [S0(CF3COOH) – S0(CF3COO–)] = 0.
(33)
Fundamentally different mechanism of participa-
tion of HX in the process of compound I oxidation is
presented in Scheme 5 considering the possibility of
coordination of O2 molecule to another electrophilic
site of substituent if its carboxy group is bound with
the acid by a strong hydrogen bond.
Scheme 5.
HX
'
CH2COOH
K1
(5.1)
I + HX
Fe
C
HX
'
CH2COOH
O2
K2
C + O2
Fe
D
O
(5.2)
CH2C
'
k1
OO
Fe+ X−
+ H2O
[R1C(O)O ]+
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

SPECIFIC FEATURES OF OXIDATION OF FERROCENYLACETIC ACID
2315
mechanism (5). More detailed analysis of the role of
νp' = [(k3.2 + k3.3)k0'/k3.7][I][O2][HX],
(39)
(40)
the approach and orientation effect in oxidation of
ferrocene derivatives is presented in [18]. Note also
that in the reaction of hydrogen abstraction from the
molecule of compound I leading to formation of the
radicals R· and R1· the peracyl radical must be more
active than HO2· because the energy of O–H bond in
RC(O)OOH (~406 kJ mol–1) is significantly higher
than the energy of this bond in H2O2 (~369 kJ mol–1
[10]). At the same time the reaction of HO2· with the
molecule of compound I is sterically more favorable.
This kinetic factor may lead to equalization of activity
of the radicals compared.
ν' = [1 + (k3.2 + k3.3)/k3.7]k0' [I][O2][HX].
Equation (40) completely corresponds to the Eq. (34).
From that it follows:
keff = k1'K1'K2'[1 + (k3.2 + k3.3)/k3.7].
(41)
EXPERIMENTAL
Oxidation of compound I was carried out in a
vacuum static installation with the intense stirring of
reaction mixture. Reaction progress was monitored by
the absorption of oxygen which was controlled
manometrically. Synthesis of compound I was carried
out according to the procedure [3]. The samples were
two times crystallized from diethyl ether.4
Hence, the comparison of the specific features of
oxidation of compound I in the absence and in the
presence of the acid III, i.e., the composition of
products, kinetic rules, and the effect of different
factors on the reaction rate, it may be concluded on
certain closeness of mechanisms of the radical chain
oxidation of compound I in the processes (1) and (2)
excluding the stage of chain generation. Just the
participation of HX in this stage of the process gives
rise to appearance of the dependence of its rate on the
concentration of acid and minimization of the
contribution of the bimolecular reaction of compound I
with O2 in the total process of oxidation of metal
complex. At the neglect of this contribution the
experimentally established rule for the rate of oxida-
tion of compound I may be regarded analogously to
the process (1) as the sum of rates of oxidation of
complex according to the molecular (ν'0) and the
radical chain (νp') mechanisms.
Solvents of the “pure for analysis” grade were
additionally purified according to the routine
procedures [29]. Analysis of compound I and the
products of its oxidation was carried out on a SKB
“Khromatek” Kristall 5000.1 chromatograph coupled
with the Termo Finnigan TRACE DSQ mass
spectrometer, RTX-5MS column, Ti 110°C, 1 minute
keeping, heating rate 15°C/min up to 250°C. Total
analysis time 30 min, vaporizer temperature 250°C,
reset 1:30, sample volume 1 μl, scanning time 30 min,
scanning rate 50–500 atomic units, amplification factor
3, scanning rate 5 scans per second, ionizing electrons
energy 70 eV.
Electron absorption spectra of solutions were
measured on a Shimadzu UV-1700 spectrophotometer
in the range 250–750 nm using the 1 cm quartz cells.
The cells with the corresponding pure solvents were
used for comparison.
v' = keff[I][O2][HX],
(34)
(35)
v' = v' + vp'.
0
Considering the assumptions similar to those
accepted in the kinetic analysis of the process (1) and
using the same numbering of the reactions as in the
Scheme 3 we obtain:
Analysis of water was carried out by means of GLC
on a Separone CHN chromatograph equipped with
katharometer, 2000×4 mm column, oven temperature
120°C, vaporizer temperature 150°C.
v' = k1'K1'K2'[I][O2][HX] = k' [I][O2][HX].
(36)
Analysis of CO and CO2 was carried out by GLC
on a Tsvet-100 chromatograph equipped with a flame
ionization detector and a plunger dosing valve, 500×4
mm column filled with the SKT activated carbon,
carrier gas argon, column temperature 90°C, reactor
temperature Tcat. 450°C.
0
0
Here k' = k1'K1'K2'.
0
νp' = 2 (k3.2 + k3.3)[R¯O2•][I],
(37)
(38)
v' = 2 k3.7[R¯O2•][I].
0
·
Expressing the radical concentration [RO2 ] from
the relationships (36) and (38) we obtain the equation
for the rate of oxidation of compound I according to
the chain-radical mechanism and in the summary
process.
4
Authors express their gratitude to Candidate of Chemical
Sciences A.S. Smirnov for supplying samples of compound I.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

2316
FOMIN, SHIROKOV
14. Energii razryva khimicheskikh svyazei. Potentsialy
The work was carried out on an equipment
ionizatsii i srodstvo k elektronu (Energies of Cleavage
of Chemical Bonds. Ionization Potentials and Electron
Affinities), Kondrat’ev, V.N., Ed., Moscow: Nauka,
1974, p. 325.
provided within the framework of the Federal Innova-
tional Educating Program “Innovational-telecommu-
nicational Systems: Physical Basis and Mathematical
Software. ”
15. Benson, S.W. and Nangia, P.S., J. Am. Chem. Soc.,
1980, vol. 102, no. 8, p. 2843.
16. Caldwell, G., Renneboog, R., and Kebarle, P., Can. J.
Chem., 1989, vol. 67, no. 4, p. 661.
17. Egorochkin, A.N., Kuznetsova, O.V., and Novikova, O.V.,
Zh. Obshch. Khim., 2007, vol. 77, no. 1, p. 68.
18. Fomin, V.M., Shirokov, A.E., and Polyakova, N.G., Zh.
Obshch. Khim., 2008, vol. 78, no. 7, p. 1125.
REFERENCES
1. Berezin, I.V. and Martinek, K., Osnovy fizicheskoi
khimii fermentativnogo kataliza (Essential Physical
Chemistry of Fermentative Catalysis), Moscow:
Vysshaya Shkola, 1977.
2. Duga, G. and Penny, K., Bioorganicheskaya khimiya
(Bioorganic Chemistry), Moscow: Mir, 1983, p. 512.
19. Denisov, E.T. and Azatyan, V.V., Ingibirovanie
tsephykhreaktsii (Inhibiting of Chain Reactions),
Chernogolovka, 1997.
20. Kotton, F. and Wilkinson, J., Sovremennaya neorgani-
cheskaya khimiya (Modern Inorganic Chemistry),
Moscow: Mir, 1969, vol. 1, p. 121.
3. Perevalova, E.G., Ustynyuk, Yu.A., and Nesmeya-
nov, A.N., Izv. Akad. Nauk SSSR, Ser. Khim., 1963,
no. 11, p. 1967.
4. Fomin, V.M., Pukhova, I.V., and Smirnov, A.S., Zh.
Obshch. Khim., 2003, vol. 73, no. 10, p. 1756.
21. Rudler, H. and Denise, B., J. Mol. Catal., A: Chem.,
5. Fomin, V.M., Klimova, M.N., and Smirnov, A.S.,
Koord. Khim., 2004, vol. 30, no. 5, p. 355.
2000, vol. 54, p. 277.
22. Fomin, V.M., Koord. Khim., 1996, vol. 22, no. 2, p. 125.
6. Comprehensive Organic Chemistry, Barton D. and
Ollis W.D., Eds., Moscow: Khimiya, 1983, vol. 4.
23. Chichibabin, A.E., Osnovnye nachala organicheskoi
khimii (Essential Organic Chemistry), Moscow: GNTI
Khimicheskoi Literatury, 1963, vol. 1, p. 605.
24. Metody elementoorganicheskoi khimii. Zhelezoor-
ganicheskie soedineniya (Methods of Organoelement
Chemistry. Organoiron Compounds), Nesmeyanov, A.N.
and Kochetkov, K.A., Eds., Moscow: Nauka, 1983,
p. 135.
7. Emmanuel, N.M., Zaikov, G.E., and Maizus, Z.K., Rol’
sredy v radikal’no-tsepnykh reaktsiyakh okisleniya
organicheskikh soedinenii (Role of the Medium in the
Radical chain Reactions of Oxidation of Organic
Compounds), Moscow: Nauka, 1973.
8. Perevalova, E.G., Grandberg, K.I., Zharikova, N.A.,
Gubin, S.P., and Nesmeyanov, A.N., Izv. Akad. Nauk
SSSR, Ser. Khim., 1966, no. 5, p. 832.
25. Nesmeyanov, A.N., Reshetova, M.D., and Perevalo-
va, E.G., Izv. Akad. Nauk SSSR, Ser. Khim., 1967,
no. 23, p. 2746.
9. Pokidova, T.S., Denisov, E.T., and Shestakov, A.F.,
Neftekhimiya, 2008, vol. 48, no. 3, p. 174.
26. Betel, D. and Gold, V., Carbonievye iony Carbonium
Ions, Moscow: Mir, 1970, p. 334.
10. Denisov, E.T. and Denisova, T.G., Kinetika i Kataliz,
1993, vol. 34, no. 2, p. 199.
27. Guthrie, J.P., Can. J. Chem., 1976, vol. 54, no. 2,
p. 202.
11. Ervin, K.M., Anusiewicz, W., Skurski, P., Simons, J.,
and Lineberger, W.C., J. Phys. Chem., A, 2003, vol. 107,
no. 41, p. 8521.
28. Hehre, J. and Pople, J.A., J. Am. Chem. Soc., 1970,
vol. 92, no. 8, p. 2191.
12. Ramond, T.H., Blanksby,S.J., Kato, S., Bierbaum, V.M.,
Davico, G.E., Schwartz, R.L., and Lineberger, W.C.,
J. Phys. Chem., A, vol. 106, no. 42, p. 9641.
13. Chase, M.W., Jr., NIST-JANAF Thermodynamical
Tables, 4th edition, J. Phys. Chem. Ref. Data, Mono-
graph 9, 1998, 1-1951.
29. Weisberger, A., Proskauer, E., Riddik, J., and Tups, E.,
Organicheskie rastvoriteli. Fisicheskie svoistva i metody
ochistki (Organic Solvents. Physical Properties and
Methods of Purification), Moscow: Inostrannaya
Literatura, 1958.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009