Kinetics and mechanism of benzyl chloride reaction with zinc in dimethylacetamide

Article abstract of DOI:10.1134/S107036321210009X

Oxidative dissolution of zinc in the system of benzyl chloride- dimethylacetamide was investigated. The reaction stereochemistry as well as intermediates and reaction products formed were studied. The kinetic and thermodynamic parameters of the process were measured. The process was shown to follow the Langmuir-Hinshelwood mechanism with the formation of benzyl radicals and mono-solvated organozinc compound on the zinc surface. The components of mixture are adsorbed at various sites of the zinc surface, while recombination and the isomerization of the benzyl radicals occurs in solution. Pleiades Publishing, Ltd., 2012.

Full text of DOI:10.1134/S107036321210009X

ISSN 1070-3632, Russian Journal of General Chemistry, 2012, Vol. 82, No. 10, pp. 1686–1699. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © A.M. Egorov, S.A. Matyukhova, E.A. Dashkova, 2012, published in Zhurnal Obshchei Khimii, 2012, Vol. 82, No. 10, pp. 1675–
1689.
Kinetics and Mechanism of Benzyl Chloride Reaction
with Zinc in Dimethylacetamide
A. M. Egorov, S. A. Matyukhova, and E. A. Dashkova
Tula State University, pr. Lenina 92, Tula, 300600 Russia
e-mail: silver_sun@inbox.ru
Received June 28, 2011
Abstract—Oxidative dissolution of zinc in the system of benzyl chloride–dimethylacetamide was investigated.
The reaction stereochemistry as well as intermediates and reaction products formed were studied. The kinetic
and thermodynamic parameters of the process were measured. The process was shown to follow the Langmuir–
Hinshelwood mechanism with the formation of benzyl radicals and mono-solvated organozinc compound on
the zinc surface. The components of mixture are adsorbed at various sites of the zinc surface, while
recombination and the isomerization of the benzyl radicals occurs in solution.
DOI: 10.1134/S107036321210009X
The organozinc compounds and the zinc complexes
with organic ligands are widely used in industry as
catalysts for the polymerization of lactones, lactides
and various aldehydes [1].
with the donor–acceptor properties are carried out in
our country and abroad.
In this work we investigated the mechanism of the
reaction of zinc with benzyl chloride to provide an
environmentally safe technology for producing benzyl-
zinc chloride of the concentration up to 7 M and the
zinc complex compounds with organic ligands.
The most promising method of the synthesis of
complex metal compounds is the interaction of a metal
with organic halide in a dipolar aprotic solvent [1].
This method allows performing the processes with
high selectivity and under mild conditions without the
use of toxic substances, and also makes it possible to
produce simultaneous organometallic compounds. Due
to this advantage, the studies on the oxidation of zinc
with organic oxidants in various non-aqueous media
The reaction of zinc with benzyl chloride in
dimethylacetamide (DMAA) in an inert atmosphere
leads to the formation of organozinc compounds and
coordination compounds of zinc, as well as of 1,2-
diphenylethane and trace amounts of 4,4'-dimethyl-
biphenyl (< 0.01%):
CH2−Cl + Zn + DMAA
CH2ZnCl•2DMAA
+ H3C
+
CH2−CH2
CH3 + [Zn(DMAA)2]Cl2
< 0.01%
The oxidative dissolution of zinc proceeded selec-
tively. Organozinc compound and 1,2-diphenylethane
yields were 92% and 8%, respectively.
solvent. These reactions as a rule occur on the metal
surface and proceed by the radical, ion-radical, or
carbanion mechanism [1–4]. The presence in the
reaction mixtures of 1,2-diphenylethane and trace
amounts of 4,4'-dimethylbiphenyl suggests that the
reaction proceeds by a radical mechanism through the
formation of the radical pair [1, 4–6].
It is known that the mechanism of the metal reac-
tion with various reagents in dipolar aprotic solvents
depends on the nature of the metal, the reagent, and the
1686

KINETICS AND MECHANISM OF BENZYL CHLORIDE REACTION
1687
To identify the reaction intermediates [1, 5], we
registered the ESR spectra at 77 K of the films of
jointly condensed zinc and benzyl chloride in the ratio
of 1:50 in accordance with the method [7]. Zinc was
evaporated from the corundum crucible in a vacuum
(570–600 K, 10–4 mm Hg) and condensed as a
molecular beam with benzyl chloride vapor on a quartz
finger cooled to 77 K. The ESR spectra of the benzyl
chloride–zinc condensate are multiplets with a total
width of about 55 gauss and the g-factor 2.002±0.001.
At the condensation of benzyl chloride on the
compact zinc film the loss of superhigh frequency in
the sample increases due to the increase in the electric
conductivity, leading to a significant loss in the the
ESR spectrum quality, but at 77 K the spectrum is not
diffuse [1, 5]. The ESR spectra in these cases consist
of a triplet of quartets (benzyl radicals) with a super-
imposed singlet of the ion-radical pair PhCH2Cl–·Znn+·.
However, the PhCH2 Cl–·Znn+·:Ph·CH2 ratio increases
~3.5 times.
Based on comparison with published data, the
obtained ESR spectra were assigned to the spectra of
the benzyl radical [4–6, 8, 9] formed at the elimination
of halogen atoms from the initial benzyl chloride by
the atomic zinc [1]:
Thus, when compact metal is used in the reaction
stabilization occurs of ion-radical pairs due to the
charge distribution over the whole group of metal
atoms [1, 5]. At the temperatures of 93–110 K the
revealed radical ions completely disintegrate as
follows [1, 5].
.
.
CH2−Cl + Zn
CH2 + ZnCl
CH2Cl−. Zn+n.
CH2 + ZnnCl
In the ESR spectra of the condensate of benzyl
chloride with the atomic zinc (the metal atom is in the
ground state) were observed the signals of two kinds:
triplets or quartets or multiplets with the superposition
of a singlet, with half-width 8±2 G [1]. Based on the
literature data [10, 11], the singlet was assigned to the
ion-radical pair PhCH2Cl–·Znn+· (n ≥ 1), the absence of
hyperfine structure was associated with the exchange
processes [10–12]:
n ≥ 1.
In the combined condensation of benzyl chloride
and dimethylacetamide on the surface of a compact
zinc the ESR signals are observed only at 77 K, and
belong only to the ion-radical pairs indicating that the
stabilization of the latter occurs not only by the metal
surface but also by the dipolar aprotic solvent
disintegrate as follows [1, 5]. Besides, the dipolar
aprotic solvent adsorbed on the compact metal film
facilitates the transfer of an electron from the metal
surface to the organic halide. At increasing the
temperature to 93 K the signals of benzyl radical
(triplet of quartets) appear in the ESR spectrum,
therewith, the ratio PhCH2Cl–·Znn+·:PhĊH2 becomes
equal to 5:1. With further increase in temperature to
110 K the signals of the ion-radical pair disappear.
CH2−Cl + Znn
CH2Cl−. Zn+n.
CH2Cl−. Zn+n.
CH2−Cl +
CH2Cl−. Zn+n.
CH2−Cl
+
It was found in [1, 5] that the reaction of benzyl
chloride with zinc occurs mainly at the C–X bond, and
the low value of the energy of this bond cleavage
prevent the insertion of zinc in the C–H bond, that is,
benzylzinc hydrides and benzylpolyzinc chlorides are
not practically formed.
In the ESR spectra of the condensate of atomic zinc
in the ground state with benzyl chloride the signals of
·
the ZnnCl radicals (n ≥ 1) were not observed, due to
the fast reaction of these radicals with a large excess of
benzyl chloride already at 77 K [1]:
A method of detection of the radical intermediates
in solution is the ESR study of the reaction at 273 K
[4, 13] using a spin trap. As a spin trap for the benzyl
radicals, we used 2,2,6,6-tetramethylpiperidine 1-oxyl,
which does not react with zinc or organozinc
compounds. The ESR spectrum of a mixture containi-
ng zinc or an organozinc compound, benzyl chloride,
DMAA, and 2,2,6,6-tetramethylpiperidine 1-oxyl
CH2−Cl + Znn
CH2 + ZnCl2 + Znn−1
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 10 2012

1688
EGOROV et al.
(1:5:8:0.2 ratio) is a triplet of 55 gauss width with the
g-factor 2.0055±0.0002, which corresponds to the
interaction of the electron with the nucleus of the
nitrogen atom in the nitroxide group. Parameters of the
ESR spectrum and literature data [14] are listed in
Table 1. A comparison with the data [14] allows the
assignment of the resulting ESR spectrum to that of
the nitroxyl radical.
CH2ZnCl + Znn−1
CH2ZnnCl
CH2ZnnCl + (n − 1)
CH2−Cl
During the reaction of zinc with benzyl chloride
in DMAA the signal of the added stable
radical 2,2,6,6-tetramethylpiperidine 1-oxyl dis-
appears from the ESR spec-trum of the reaction
mixture.
2,2,6,6-Tetramethylpiperi-dine
1-oxyl
can react with traces of the formed hydrogen
chloride, the parent benzyl chloride, and benzyl
radicals [1]:
H3C
H3C
H3C
H3C
CH3
CH3
Cl−
H3C
H3C
CH3
CH3
Cl−
CH3
CH3
+
+
2
+ HCl
N+
O
NH
N
O
.
HO
H3C
CH3
H3C
H3C
H3C
CH3
CH3
Cl−
CH3
CH3
N−O−CH2−Ph
+
2
+ PhCH2Cl
N+
O
N
O
H3C
.
CH3
H3C
H3C
CH3
H3C
H3C
CH3
.
2
+ PhCH2
N−O−CH2−Ph
N
O
CH3
.
CH3
H3C
H3C
CH3
H3C
H3C
H3C
CH3
CH3
N−O−CH2−Ph
CH3
+
2
+ PhCH2ZnCl
N
O
N
H3C
CH3
CH3
OZnCl
.
H3C
Therewith, the tetramethylpiperidine oxide
salt can be reduced by hydrogen peroxide in
alkaline medium to afford the corresponding radical
[4, 15]:
H3C
CH3
H3C
CH3
+ O2 + 2H2O + 2KCl
2
+
2
+ 2KOH + H2O
N
O
N
O
H3C
CH3
H3C
CH3
Cl−
.
The treatment of reaction mixtures with hydrogen
peroxide in alkaline medium [4, 15] did not result in
restoring the ESR signal, indicating the presence of
radical intermediates in solution [15]. It is likely that
benzyl radicals are formed and react with the trap
along the scheme:
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 10 2012

KINETICS AND MECHANISM OF BENZYL CHLORIDE REACTION
1689
H3C
CH3
H3C
H3C
.
CH3
CH3
+ PhCH2
N−O−CH2−Ph
CH3
N
O
.
H3C
To test this hypothesis, we attempted to detect
the benzyl radicals in solution using a spin trap.
As the chemical trap for the benzyl radical we used
dicyclohexyldeuterophosphine
(DCPD),
which
did not react with organozinc compounds or zinc
powder:
DCPD
.
CH2ZnCl DMAA
CH2−Cl + Zn + DMAA
+
CH2D + [Zn(DMAA)2]Cl2
After separation of [Zn(DMAA)2]Cl2, the reaction
mixture was treated with 20% HCl in H2O. The yield
of the organozinc compound is equal to the amount of
the formed toluene:
.
.
CH2ZnCl 2DMAA + HCl
CH3 + [ZnCl2 2H2O] + 2DMAA
Table 2 lists the yields of the organic products of
oxi-dativ dissolution of zinc in the benzyl chloride–
dimethylacet-amide system in the absence and the
presence of DCPD.
biphenyl. Nevertheless, the amount of detected α-
deuterotoluene exceeds the amount of isolated 1,2-
diphenylethane. This means that at least 50% of
benzylzinc chloride is formed in the reaction of •ZnCl
with benzyl radicals that are released into the solution
and return to the zinc surface.
The presence in the reaction mixtures of α-
deutero-toluene can be associated only with the
presence of benzyl radicals in the solution:
To study the pathways of the formation of reaction
products and to confirm experimentally the retention
of optical activity at the asymmetric center at the
formation of the zinc–carbon bond, we synthesized
(+)-R-1-chloro-1-phenylethane and investigated the
stereochemistry of its reaction with metallic zinc in
dimethylacetamide.
.
P
CH3
+
D
.
PH
CH2D
+
The reaction of (+)-R-1-chloro-1-phenyletane with
metallic zinc in the presence of dimethylacetamide
was carried out along the following scheme:
The benzyl radicals leaving the zinc surface are
captured by DCPD. Thus, the recombination and
isomerization of benzyl radicals in solution leads to
the formation of 1,2-diphenylethane and 4,4'-dimethyl-
Table 2. Yields of organic products at the oxidative dissolu-
tion of zinc in the system benzyl chloride–dimethylacet-
amide without an additive and in the presence of dicyclo-
hexyldeuterophosphine
Table 1. ESR spectral parameters of tetramethylpiperidine 1-oxyl
Solvent
g-Factor
aN, G
aН, G
ΔН, G
а
Yield,a mol %
2.0055±0.0002 16.6±0.1 0.2±0.1 1.5±0.3
DCPD:PhCH2Cl t, h
Beene
Diethyleneglycol
Formamide
2.0055
2.0055
2.0055
15.4±0.1 0.2±0.2 1.5±0.2
16.2±0.1 0.2±0.2 1.5±0.2
16.4±0.1 0.2±0.2 1.5±0.2
PhCH3
PhCH2CH2Ph PhCH2D
0:1
5:1
2
2
92
36
8
–
–
64
a
Obtained in this work in the system of benzyl chloride–dimethyl-
acetamide (molar ratio 5:8).
a The 4,4'-dimethylbiphenyl yield is less than 0.01%.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 10 2012

1690
EGOROV et al.
H
H
.
C−CH3 + Zn + DMAA
C−ZnCl 2DMAA
Cl
CH3
(+)-R
H
C
CH3
C
H
C
H
C
+
+
CH3
H
CH3
CH3
RS, RS (41.2%)
RR, SS (40%)
CH=CH2 + [Zn(DMAA)2]Cl2
+
CH2−CH3 +
4%
4%
H
H
.
.
.
C−CH3 + ZnCl2 2DMAA
C−ZnCl 2DMAA + DCl
D
CH3
RS
After processing the reaction mixtures with 20%
DCl in D2O racemic RS-1-deutero-1-phenyletane was
isolated. This fact indicates stereochemical instability
of the Zn–C bond and suggest a radical nature of its
formation and decay. The RS,RS-2,3-diphenylbutane
and RR,SS-2,3-diphenylbutane also were optically
inactive, and their ratio in all cases was about 1.03:1,
the styrene:ethylbenzene ratio was equal to 1:1. This
ratio agrees well with published data on the behavior
of 1-phenylethyl radicals in the solvent cage [16], so
it can be concluded that the reaction of zinc with (+)-
R-1-chloro-1-phenylethane proceeds by a radical
mechanism through the formation of 1-phenylethyl
radicals, which suffer recombination and dispropor-
tionation in the solution.
The Langmuir–Hinshelwood scheme assumes that
the limiting stage of reaction is the interaction of
adsorbed reagent and solvent molecules with the
surface of the metal undergoing the oxidation, that is,
occurs a chemical reaction on the surface.
Consider several versions of the Langmuir–
Hinshelwood mechanism that are possible if this
mechanism is realized.
(1) At the equilibrium adsorption of reagent and
solvent at different active sites of the metal surface
and their further interaction the Langmuir–Hinshel-
wood scheme is as follows [1]:
K1
RHal + S1
L + S2
(RHal)S1,
K2
It is known that the reactions of various reagents
and dipolar aprotic solvents with the metal surface,
usually proceed by either the Langmuir–Hinshel-
wood, or Eley–Rideal mechanism.
(L)S2,
k3
(RHal)S1 + (L)S2
Reaction products.
Here and hereinafter RHal is the organic halide, L is a
dipolar aprotic solvent, S1 and S2 are the active sites
of the metal surface where the adsorption of organic
halide and dipolar aprotic solvent, respectively,
occurs; K1 and K2 are the equilibrium constants of
adsorption of organic halide and dipolar aprotic
solvent, respectively, k3 is the rate constant of the
chemical process.
The Langmuir–Hinshelwood mechanism [1, 17]
comprises the following steps: equilibrium and
independent of each other adsorption of the reagent
and solvent molecules at the metal surface, which can
occur either on identical or on different active sites of
the metal, and the interaction of adsorbed reagent and
solvent molecules with the metal surface and
formation of intermediates or reaction products.
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KINETICS AND MECHANISM OF BENZYL CHLORIDE REACTION
1691
The nature of active sites adsorbing organic halide
and dipolar aprotic solvent is not completely
understood, however, due to the heterogeneity of the
metal surface it contains the areas that differ in
geometry and energy characteristics. The kinetic
equation includes the degree of surface coverage
obtained from the Langmuir isotherm for the
adsorption of each component, and the expression for
the reaction rate w is as follows:
(3) At the equilibrium adsorption of organic halide
(RHal) and solvent (L) on the identical active sites of
the metal surface (S), followed by the equilibrium
formation of the surface-linked intermediates, the
scheme of the Langmuir–Hinshelwood mechanism is
as follows [1]:
K1
RHal + S
(RHal)S,
K2
L + S
(L)S,
kK1K2[RHlg][L]
w = —————–——————————– ,
1 + K1[RHal] + K2[L] + K1K2[RHal][L]
K
(RHal)S + (L)S
(RHal)(L),
where k = k3N1N2, N1 and N2 are the numbers of
active centers of the metal surface adsorbing organic
halide and dipolar aprotic solvent, respectively.
k3
(RHal)S + (L)S
Reaction products.
The expression for the rate of the process is as
If the process proceeds according to the
Langmuir–Hinshelwood mechanism with the adsorp-
tion of organic halide and dipolar aprotic solvent at
different active centers of the metal, then the plots of
the reaction rate vs. the initial concentration of the
components in the mixture are smooth curves without
maxima.
follows:
kK1K2K[RHal][L]
w = —————–——————————–– ,
1 + K1[RHal] + K2[L] + K1K2K[RHal][L]
k = k3N.
In the process by the Langmuir–Hinshelwood
mechanism with the adsorption of organic halide and
dipolar aprotic solvent at identical active sites of the
metal surface with the formation of the surface-bound
intermediates, the plots of the reaction rate on the
initial concentration of the components in the mixture
are smooth curves without peaks.
(2) When the equilibrium adsorption of organic
halide (RHal) and solvent (L) occurs on the identical
active sites of the metal surface (S) and they interact
irreversibly with the metal surface resulting in the
formation of intermediates or the products of the
reaction, then the scheme of the Langmuir–Hinshel-
wood mechanism is as follows [1]:
The Eley–Rideal mechanism [1, 17] comprises
the following steps: the equilibrium adsorption of reactant
molecules on the metal surface and the interaction of
adsorbed molecules of reagent with the metal when
the coordinating solvent molecules from the solution
approach them and the reaction products are formed.
Consider two versions of the Eley–Rideal mechanism
which are possible at the process implementation.
K1
RHal + S
L + S
(RHal)S,
(L)S,
K2
k3
(RHal)S + (L)S
Reaction products.
(1) At the equilibrium adsorption of the reactant
molecules (RHal) only on the metal surface, the
Eley–Rideal scheme has the form [1]:
K1
The expression for the rate is as follows:
kK1K2[RHal][L]
w = —————–————– ,
(1 + K1[RHal] + K2[L])2
RHal + S
(RHal)S,
k = k3N 2.
k3
(RHal)S + L
Reaction products.
In the process proceeding by the Langmuir–
Hinshelwood mechanism with adsorption of organic
halide and dipolar aprotic solvent at identical active
sites of the metal surface without the formation of
surface-bound intermediates, the plots of the reaction
rate vs. the concentration of the initial components in
the mixture are smooth curves with maxima (the
extreme character of the curves).
The expression for the rate of the process in this
case is:
kK1[RHal][L]
w = ––———–—– ,
1 + K1[RHal]
k = k3N.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 10 2012

1692
EGOROV et al.
(2) At the equilibrium adsorption of the reagent
concentration of dipolar aprotic solvent from 0.5 to 2
M does not lead to a change in the form of the
dependence of reaction rate on the concentration of
benzyl halide, indicating that these reactions proceed
by Langmuir–Hinshelwood mechanism. However, in
contrast to [5] we obtained the reaction rate
dependences on the concentrations of the components
of zinc–benzyl chloride mixture in dimethylacetamide
like smooth curves without extremal points (Fig. 1),
indicating that the adsorption of benzyl halide and
dimethylacetamide occurs on the different active sites
of the metal surface.
(RHal) molecules as well as the solvent (L) molecules
on the metal surface, followed by the reaction of the
adsorbed reactant (RHal)S with the metal at the
approach to them of coordinating solvent (L)
molecules from the solution the Eley–Rideal scheme
has the form [1]:
K1
RHal + S
L + S
(RHal)S,
(L)S,
K2
k3
(RHal)S + L
Reaction products.
Thus, the reaction of zinc with benzyl chloride in
dimethylacetamide proceeds by the Langmuir–
Hinshelwood mechanism, through the adsorption of
the reagent and solvent at different active sites of the
metal surface and their further interaction.
The equation for the process rate in this case is:
kK1[RHal][L]
w = —————–————— ,
1 + K1[RHal] + K1[RHal]
k = k3N.
For processing the experimental curves, we
applied the previously developed algorithms [1],
which allow determining not only the rate constant k,
but also the equilibrium constants of benzyl halide
and solvent adsorption on the metal surface (K1 and
K2). While investigating the reaction kinetics at
different temperatures, we were able to determine the
activation energy Ea of the chemical process, and the
standard enthalpy and entropy of the reactant and
solvent adsorption on the zinc surface.
At the implementation of the process by the Eley–
Rideal mechanism the general form of the plots of the
reaction rate vs. concentration of components in the
mixture changes in going from the solvent (at a fixed
concentration of benzyl halide) to benzyl halide (at a
fixed concentration of the solvent): one plot is a
straight line, and the other is a smooth curve.
To reveal the kinetic and thermodynamic
characteristics of the interaction of zinc with benzyl
chloride in the presence of dimethylacetamide, we
used the resistometric method, which is sufficiently
precise and reproducible [18–20]. The reactions were
studied in an indifferent solvent benzene at the stirrer
rotation rate from 2500 to 2700 rpm, which enabled
to study the process in the kinetic region.
The results of studying the reaction kinetics of
zinc with benzyl chloride in dimethylacetamide are
listed in Table 3.
The correlation coefficients R are close to unity,
and the standard deviations are minimal that confirm
the high accuracy of both the method and the data.
The dependence of the reaction rate of zinc with
benzyl chloride in dimethylacetamide is a smooth
curve in the coordinates the rate (w) is the initial
concentration of the component (Fig. 1).
The listed in Table
3
different values of
ΔH0(PhCH2Cl) –23.1±0.9 kJ mol–1 and ΔH0DMAA
–28.2±1.4 kJ mol–1 indicate that benzyl chloride and
dimethylacetamide are adsorbed on different active
sites of zinc surface. Value of the ΔH0(PhCH2Cl) –
23.1±0.9 kJ mol–l for the reaction of zinc with benzyl
chloride in dimethylacetamide coincides with
ΔH0(PhCH2Cl) –22.9±0.8 kcal mol–1 [5] for the
reaction of zinc with benzyl chloride in DMF,
indicating that benzyl chloride is adsorbed in these
reactions at the sites of the same energy and its
adsorption is practically independent of the influence
of the solvent.
In [5] the dependences were reported of the zinc–
benzyl chloride reaction rate in dimethylformamide
on the concentration of the mixture components,
which are smooth curves with extrema (Fig. 2). In
this case (Fig. 2) the process obeyed the Langmuir–
Hinshelwood mechanism with adsorption of organic
halide and dipolar aprotic solvent on the identical
active sites of zinc surface without the formation of
surface-bound intermediates [5].
Significant negative values of ΔS0(PhCH2Cl)
Comparison of the results obtained in this paper
with the data of [5] show that in both cases increasing
–80.0±3.0 J mol–1 K–1 and ΔS0DMMA –106±5 J mol–1 K–1
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 10 2012

KINETICS AND MECHANISM OF BENZYL CHLORIDE REACTION
1693
w×104, g cm–2 min–1
w×104, g cm–2 min–1
с, M
с, M
Fig. 2. Dependence of the reaction rate (w) of zinc with
benzyl chloride in dimethylformamide on the concentration
of the components of the mixture at 283 K in the presence
of an indifferent solvent (benzene) [5]. (1) cDMF = 0.5 M,
c(PhCH2Cl) from 0 to 7.0 M, (2) c(PhCH2Cl) = 0.5 M;
Fig. 1. Dependence of the reaction rate (w) of zinc with
benzyl chloride in dimethylacetamide on the concentration
of the components of the mixture at 293 K in the presence
of benzene. (1) cDMAA = 0.5 M, c(PhCH2Cl) from 0 to
7.0 M , (2) c(PhCH2Cl) = 0.5 M; cDMAA from 0 to 7.0 M,
(3) cDMAA = 2.0 mol l–1, c(PhCH2Cl) from 0 to 7.0 M.
c
DMF from 0 to 7.0 M, (3) cDMF = 2.0 M, c(PhCH2Cl) from
0 to 7.0 M.
shown in Table 3 indicate that there is no dissociation
of benzyl chloride and dimethylacetamide during the
adsorption. For comparison, the standard entropy of
adsorption of the reagent and solvent for the reaction
of zinc with benzyl chloride in DMF, which also do
not dissociate during adsorption are: ΔS0(PhCH2Cl)
–79±4 J mol–1 K–1; ΔS0DMMA –101±7 J mol–1 K–1 [5].
constants of the unsubstituted substrate. The relative
reactivities of the benzyl chlorides were obtained by
dividing the rate constants of the substituted benzyl
chloride ks by that of the unsubstituted chloride k [1,
21]. This allowed calculating the ρ parameter of the
Hammett equation. Table 4 shows the Hammett σ
constants of substituents and relative reactivities of
substituted benzyl chlorides at 293 K in the reaction
with zinc in dimethylacetamide. Figure 3 shows the
plot of the logarithms of relative rates on the σ
Hammett constants of substituents. The data in Table 4
show that the dependence is a straight line with good
correlation. Comparison of the kinetic parameters of
the reaction shows that the nature of the substituent in
To study quantitatively the influence of the
substituents in the aromatic ring on the reactivity of
benzyl chloride in the reaction with metallic zinc in
dimethylacetamide, we measured the reaction rate
constants with the substituted benzyl chlorides (ks) at
293 K in the same way as were measured the rate
Table 4. Relative reactivity of benzyl chlorides at 293 K in
the reaction with zinc in dimethylacetamide
Table 3. Kinetic and thermodynamic parameters of reaction
betwen zinc and benzyl chloride in dimethylacetamidea
Т, K k×103, g cm–2 min–1b K1, l mol–1 c
K2, l mol–1 d
ks×103,
Substituent
σ
log (ks/k)
ks/k
g cm–2 min–1
283
293
303
313
323
333
1.22±0.02
3.18±0.04
7.34±0.08
15.1±0.02
36.9±0.04
68.9±0.06
1.23±0.01
0.862±0.008
0.625±0.006
0.479±0.005
0.351±0.004
0.283±0.003
0.445±0.005
0.292±0.003
0.201±0.002
0.133±0.001
0.103±0.001
0.0731±0.0007
m-Cl
m-F
p-Cl
m-OMe
p-F
H
m-Me
p-Me
p-OMe
0.37
0.34
0.23
0.12
0.06
0
–0.07
–0.17
–0.27
0.161368
0.149219
0.136721
0.029384
0.049218
0
–0.03152
–0.05061
–0.13668
1.45
1.41
1.37
1.07
1.12
1
0.93
0.89
0.73
4.61±0.04
4.48±0.04
4.36±0.04
3.40±0.03
3.56±0.04
3.18±0.04
2.96±0.03
2.83±0.02
2.32±0.02
Ea 63.3±2.4; ΔH0(PhCH2Cl) –23.1±0.9 kJ mol–1, ΔH0
–28.2±1.4 kJ mol–1 at 298 K, ΔS0(PhCH2Cl) –80.0±3,0 J mol–D1MKA–A1
and ΔH0DMAA –106±5 J mol–1 K–1. Selective correlation coef-
ficient for the plot lnY = f (1/T). bR = 0.999 (Y = k), c R = 0.999
(Y = K1), d R = 0.999 (Y = K2).
a
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1694
EGOROV et al.
the aromatic ring has little effect on the reaction rate,
The reaction in all cases is not limited by diffusion
and/or mass transfer of compound I. The value of ρ is
too large compared to the physical adsorption of the
component II. The sign of ρ is not typical for the
processes of formation of benzyl cation V. The
obtained ρ values are much lower than those found in
the reactions with the participation of benzyl anion
IV. The results of the study of the reaction
stereochemistry of zinc with benzyl chloride allow
the rejection of the processes similar to the SN2 with
intermediate VII and the processes that include the
formation of at-complexes X. The rate determining
step that includes the intermediate IX with partial or
complete formation of the metal–carbon bond is
hardly probable, since in this transition state there is a
significant charge on carbon and a high ρ value is
typical in this case. These results do not allow us to
specify the reactions leading to the formation of the
three remaining states: the single electron transfer
with the formation of the anion radical III, the
splittiong off the chlorine atom (the reaction product
is VI), and the insertion of zinc atom in the C–Hal
bond forming VIII.
and the rate constants ks vary insignificantly.
Thus, the results obtained indicate that the
electron-withdrawing substituents in the aromatic
ring make the interaction of benzyl chloride with zinc
slightly easier, while electron-releasing substituents
retard the process, therewith the mechanism of these
processes remains unchanged.
To determine the rate limiting steps, we con-
sidered 10 possible processes that may occur in these
steps:
Zn
CH2 Cl
CH2 Cl
I
II
_
_
CH2 Cl
CH2
III
IV
+
CH2
CH2
V
VI
Our studies using the ESR spectroscopy, radical
trapping and investigating the reaction stereo-
chemistry showed that the reaction of zinc with
benzyl chloride in dimethylacetamide proceeds by the
mechanism of halogen transfer with the formation of
benzyl radicals VI, as evidenced also by the low
positive Hammett ρ value.
CH2
Zn
Cl
Cl
CH2
Zn
Like SN2
VII
VIII
CH2ZnCl Zn+ Cl_ CH2
Based on the results obtained and literature data
we assume the following mechanism of reaction of
benzyl chloride with zinc in dimethylacetamide:
IХ
Х
Stage I: reversible adsorption of benzyl chloride
on the surface of the active sites of zinc, which have
certain energy characteristics:
log (ks/k)
CH2−Cl
K1
σ
CH2−Cl
Fig. 3. Effect of substituent at the aromatic ring on the
reaction of zinc with benzyl chloride in dimethylacetamide,
ρ = 0.45±0.03, Sρ = 0.02, R = 0.9814, R2 = 0.9631.
CH2−Cl + nZn
Znn
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KINETICS AND MECHANISM OF BENZYL CHLORIDE REACTION
1695
The aromatic ring is oriented parallel to the metal
surface and the halogen atom is located above the
plane of the ring [1]:
CH2−Cl + DMAA
Znn
H
C
.
CH2
Znn
.
Stage II: reversible adsorption of DMAA on
the active sites of zinc surface with different energy
characteristics. Partial electron transfer from zinc to
DMAA greatly facilitates the transfer of an electron
from the surface of zinc on the benzyl chloride:
CH2−Cl + ZnCl DMAA
Znn−1
The benzyl group on the surface reversibly
releases an electron. The structure of the benzyl
group can be represented as follows:
DMAA
K2
.
CH2
CH2
DMAA
DMAA + nZn
Znn
Znn−1
Znn−1
By the method of scanning tunnel microscopy it
was found that aromatic radicals can move along the
surface of a metal at sufficiently large distances [1].
Stage III: transfer of electrons from the zinc
surface in the inner sphere (the mechanism of halogen
transfer). At this stage benzyl radicals are formed and
solvated radical ·ZnCl·DMAA on the surface of zinc.
The resulting benzyl radicals can reversibly transit to
the solution. Solvated radical ·ZnCl·DMAA does not
go into solution as it is part of the surface:
Stage IV: the interaction of the benzyl radical with
solvated radical ·ZnCl·DMAA may proceed by both
the Langmuir–Hinshelwood and Eley–Rideal mechanism
when the radical attacks from the solution:
.
CH2
.
.
CH2 + ZnCl DMAA
Znn−1
.
CH2ZnCl DMAA + Znn−1
.
ZnCl DMAA
.
CH2 +
Znn−1
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1696
EGOROV et al.
Stage VI: formation of the reaction by-products. A
Stage V: solvation of the monosolvated benzylzinc
chloride in the solution:
fast reaction occurs of solvated zinc chloride radical
located on the zinc surface with benzyl chloride either
on the zinc surface by the Langmuir–Hinshelwood
scheme, or it is attacked with benzyl chloride from
the solution by the Eley–Rideal scheme:
.
CH2ZnCl DMAA + DMAA
.
CH2ZnCl 2DMAA
.
.
ZnCl2 DMAA
CH2
.
CH2−Cl + ZnCl DMAA
Znn−1
.
.
ZnCl DMAA
.
CH2
+
ZnCl2 DMAA
CH2−Cl +
Znn−1
Znn−1
Stage VII: solvation of the monosolvated zinc
chloride in the solution:
Stage VIII: recombination and isomerization of
benzyl radicals in the solution.
ZnCl2·DMAA + DMAA → ZnCl2·2DMAA
The mechanism of the reaction of zinc with benzyl
.
.
+
CH2
CH2
. . .
CH2
CH2
H2C
H2C
. . .
H3C
CH3
H3C
CH3
chloride in dimethylacetamide studied in this work is
similar to the mechanism of the reaction of zinc with
benzyl chloride in dimethylformamide reported in
[5]. Both the mechanisms include the transfer of the
halogen atom and the formation of benzyl radicals,
which recombine and isomerize in solution. The
difference between these mechanisms is that in the
reaction with DMF the benzyl chloride and the
dipolar aprotic solvent the adsorption occurs on the
similar active sites of zinc surface [5], while in the
case of the reaction using as solvent dimethyl
acetamide the solvent and reactant adsorption occurs
on different active sites of the metal surface.
EXPERIMENTAL
The purity of the starting compounds and analysis
of reaction products were monitored by the methods
of gas–liquid chromatography (chromatograph Tsvet-
800, Russia), ion chromatography (Tsvet-3006,
Russia) along the techniques described in [4]; by the
NMR spectroscopy (an NMR Fourier spectrometer
Jeol FX-90Q LTD, Japan), the analysis conditions
have been published earlier [4]; by IR spectroscopy (a
Nicolet IMPACT 400d instrument, USA) from tablets
of KBr; by ESR spectroscopy (an electron spin
resonance spectrometer SE/H-2543 Radiopan,
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KINETICS AND MECHANISM OF BENZYL CHLORIDE REACTION
1697
Poland) using previously described technique [4–6];
by the method of gas chromatography–mass spectro-
metry (mass detector HP-5972, gas chromatograph
HP-5890 Hewlett Packard, USA ), the conditions of
analysis are described in [18, 22]; by elemental
analysis (Gas chromatographic elemental analyzer
Carlo-Erba-1100, Italy) by standard methods [1].
solved gases by repeated freezing in liquid nitrogen
and thawing under reduced pressure, and stored in
ampules without air access.
(+)-R-1-Chloro-1-phenylethane was synthesized
along the procedure in [28] by reacting (–)-S-1-
phenylethanol with phosphoryl trichloride and
pyridine in pentane. The compound obtained was
freed from dissolved gases by repeated freezing and
thawing under reduced pressure and stored in
ampules without air access. Yield 75%, bp 80–81°C
(17 mm Hg), αD25 +94.1° (neat liquid, l = 1).
Published: bp 78–82°C (17 mm Hg), αD25 + 125.4°
Quantitative analysis of metal impurities in zinc
was carried out by atomic absorption spectrometry on
a GBC AVANTA PM instrument (Australia) after
dissolving the samples of the metal in nitric acid and
neutralizing the resulting solution with 25% solution
of ammonia [23].
1
(neat liquid, l = 1, for 100% optical purity) [28]. H
NMR spectrum, δ, ppm: 1.68 d (3H, CH3), 4.86 q
(1H, CH), 7.14 m (5H, arom.). Mass spectrum (EI, 70
eV), m/z (Irel,%): 142 [M]+ (6.4), 140 [M]+ (19.2), 125
[M – CH3]+ (7.7), 105 [M – Cl]+ (100), 79 [M – Cl –
C2H2]+ (11.5), 77 [M – Cl–C2H4]+ (12.8).
Organic reaction products were separated by
preparative liquid chromatography (chromatograph
Tsvet-304, Russia). Conditions of analysis are
described in [4]
Elemental analysis of deuterated organic com-
pounds was carried out on a gas-chromatographic
elemental analyzer Carlo-Erba-1100 (Italy) and gas
chromatograph Tsvet-570 (Russia) by the method [24].
(–)-S-1-phenyletanol was synthesized along the
procedure in [29] by reacting acetophenone with (–)-
S-BINAL-H in THF at –70°C. Yield 8.16 g ( 68%),
bp 94–95°C (14 mm Hg), αD25 –42˚ (neat, l = 1), 95%
optical purity; published: bp 94–95°C (14 mm Hg),
Measurement of specific rotation of the plane-
polarized light was carried out on an automatic
polarimeter VNIEKIprodmash A-1 EPO (Russia, σ =
0.01˚) in cells of various thicknesses.
αD25 –44.2˚ (neat, l = 1, 100% optical purity) [29]. H
1
NMR spectrum, δ, ppm: 1.68 d (3H, CH3), 4.86 q
(1H, CH), 7.14 m (5H, arom.). Mass spectrum (EI,
70 eV), m/z (Irel., %): 186 [M]+ (0,6), 184 [M]+ (0.6),
105 [M – Br]+ (100), 91 [M – CH2Br] (7.7), 79 [M –
Br – C2H2]+ (11.5), 77 [M – Br – C2H4]+ (14.1), 51
[M – Br–C3H6]+ (12.8).
Zinc powder PTs0 (GOST 3640-94 [25], of
Belovsky Plant, Russia), fine-dispersed, was used
without further purification. The particles size 63–77
μm purity 99.9806%. Zinc powder was activated with
1,2-dibromomethane. Zinc wire ZN005115 (Good-
fellow Corp.), d = 0.25 mm±1%, l = 100 mm±0.05%,
99.9915% purity) prior to the experiment was cleaned
mechanically to remove oxide film, then kept for 10 s
in nitric acid, washed with distilled water, acetone,
and dimethylacetamide.
Synthesis of the coordination compounds of
zinc [1]. To 1.7 g (26 mmol) of zinc powder was
slowly added (1 drop every 5 s) a solution of
21.5 mmol of benzyl chloride in 11 ml of dimethyl-
acetamide. The zinc powder was pre-activated with
one drop of 1,2-dibromoethane by the known method
[8]. The reaction was performed in an argon
atmosphere at 0°C. The mixture was stirred for 2 h
and then filtered. To the filtrate was added 50 ml of
water-free benzene. The precipitated white crystals were
filtered off on a glass filter, washed with hexane, and
then evacuated. Yield of [Zn(DMAA)2Cl2] 49.8%,
mp 119–120°C. Published: mp 119–120°C [30]. IR
spectrum (KBr), cm–1: ν(C=O) 1620, 1603. Found, %:
C 30.95, H 5.87, Cl 22.81, N 9.01, O 10.31, Zn 21.05.
C8H18Cl2N2O2Zn. Found, %: C 30.94, H 5.84, Cl
22.83, N 9.02, O 10.30, Zn 21.07.
All organic compounds were obtained from com-
mercial sources. Benzyl chloride, analytical grade
(Reahim, Russia) was dried over CaCl2 and distilled
in a vacuum, bp 65–66°C (11 mm Hg) The literature
data: bp. 66°C (11 mm Hg) [26]. N,N-Dimethyl-
acetamide (Aldrich Chemicals, 98%) was dried over
P2O5, boiled for 2 h over CaH2, and distilled in a
vacuum in a stream of nitrogen, bp 83.8–84.0°C (32
mm Hg), nD20 1,4307. The literature data: bp 84.0°C
(32 mm Hg), nD20 1.4308 [26]. Toluene, tetrahydro-
furan, benzene, acetonitrile, and other solvents were
purified according to conventional techniques [27].
Benzyl chloride and all solvents were freed from dis-
By gas chromatography–mass spectrometry (EI,
70 eV) in the filtrate were found unreacted benzyl
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1698
EGOROV et al.
chloride, dimethylacetamide and the reaction pro-
ducts: toluene, 1,2-diphenylethane and trace amounts
of 4,4'-dimethylbiphenyl. The characteristics of the
products are as follows.
Toluene, Mass-spectrum, m/z (Irel., %): 92.06 [M]+
(71.8), 91 [MH]+ (100), 90 [M – 2H]+ (5.1), 65 [M –
C2H3]+ (12.8), 63 [M – C2H4]+ (10.3). M 92.06.
dimethylacetamide was studied by a resistometric
method [18–20] in the atmosphere of anhydrous
argon freed from oxygen. The stirring rate was 2500–
2700 rpm. At the rotation rate 2000 rpm and higher
the rate of zinc dissolution in the medium under study
did not depend on the stirring rate, indicating that the
studied process is in the kinetic regime.
As an indifferent solvent in determining the
kinetic characteristics of the interaction of zinc with
benzyl chloride in dimethylacetamide was used
benzene [4].
1,2-Diphenylethane, Mass-spectrum, m/z (Irel.,
%): 182 [M ]+ (23), 91 [M/2]+ (100). M 182.11.
4,4'-Dimethylbiphenyl, Mass-spectrum, m/z (Irel.,
%): 182 [ M]+ (100), 167 [M – CH3]+ (56), 152 [M –
2CH3]+ (15). M 182.11.
ACKNOWLEDGMENTS
Investigation of the reaction of benzyl chloride
with zinc in dimethylacetamide in the presence of
radical trap was performed similar to the synthesis of
the zinc coordination compounds. Dicyclohexyl-
deuterophosphine was used as the radical trap, molar
ratio of zinc: dicyclohexyldeuterophosphine 1: 0–5.
This work was financially supported by the
programs of the Ministry of Education “Fundamental
research of Higher education schools in the area of
natural and human sciences. Universities of Russia,”
grant no. UR.05.01.012 and the Federal Education
Agency “Development of Scientific Potential of
Higher Education.”
After the precipitate separated in the ether–alcohol
solution by gas chromatography–mass spectrometry
α-deuterotoluene, toluene, and unreacted benzyl chlo-
ride were detected. The yields of organic reaction
products are shown in Table 2.
REFERENCES
1. Egorov, A.M., Doctorate (Chem.) Dissertation, Tula,
2008.
2. Garst, J.F. and, Ungváry, F., in Grignard Reagents:
New Developments, Chichester: John Wiley & Sons,
2000, ch. 7, p. 185.
α-Deuterotoluene. Yield 64%, 110°C (published
1
bp 110.6°C [26]). H NMR spectrum, δ, ppm: 2.32 m
(2H, CH2), 7.15 m (5H, arom.). Mass-spectrum (EI,
70 eV), m/z (Irel., %): 93 [M]+ (100), 92 [MH]+ (93),
91 [MD]+ (46), 66 [M – C2H3] (9), 65 [M – C2H2D]
(11). Found, %: C 90.29, H 7.53, D 2.18. C7H7D.
Calculated, %: C 90.27, H 7.56, D 2.17.
3. Guijarro, A., Rosenberg, D.M., and Rieke, R.D.,
J. Am. Chem. Soc., 1999, vol. 121, no. 17, p. 4155.
4. Egorov, A.M., Matyukhova, S.A., Kocherova, I.S.,
Novikova, A.N., and Anisimov, A.V., Zh. Obshch.
Khim., 2009, vol. 79, no. 3, p. 455.
5. Egorov, A.M., J. Phys. Org. Chem., 2006, vol. 19,
Investigation of the process stereochemistry was
carried out by the method similar to the synthesis of
the zinc coordination compounds. As a benzyl halide
(+)-R-1-chloro-1-phenylethane was used. After
precipitation the following reaction products were
detected in ether by gas chromatography–mass spec-
trometry: RS,RS-2,3-diphenylbutane, RR,SS-2,3-di-
phenylbutane, ethylbenzene, and styrene, as well as
unreacted (+)-R-1-chloro-1-phenylethane and di-
methylacetamide. All organic reaction products were
isolated by preparative liquid chromatography, yields
are shown in the scheme of the reaction of (+)-R-1-
chloro-1-phenylethane with zinc. The physico-
chemical properties of isolated RS,RS-2,3-diphenyl-
butane, RR,SS-2,3-diphenylbutane, ethylbenzene and
styrene correspond to the published data [26, 31].
no. 10, p. 664.
6. Egorov, A.M., Matyukhova, S.A., and Anisimov, A.V.,
J. Phys. Org. Chem., 2005, vol. 18, no. 10, p. 1023.
7. Sergeev, G.B., Smirnov, V.V., and Zagorskii, V.V.,
Vestn. Mosk. Univ., Ser. 2: Khim., 1980, vol. 21, no. 3,
p. 257.
8. Organozinc Reagents: A Practical Approach, Knochel, P.
and Jone, R., Eds., Oxford: Oxford Univ. Press, 1999.
9. Egorov, A.M. and Anisimov, A.V., Appl. Organomet.
Chem., 1995, vol. 9, no. 2, p. 285.
10. Sergeev, G.B., Smirnov, V.V., and Zagorsky, V.V.,
J. Organomet. Chem., 1980, vol. 201, no. 1, p. 9.
11. Sergeev, G.B, Zagorsky, V.V., and Badaev, F.Z.,
J. Organomet. Chem., 1983, vol. 243, no. 2, p. 123.
12. Mendkovich, A.S. and Gul’tyai, V.P., Teoreticheskie
osnovy khimii organicheskikh anion-radikalov
(Fundamentals of the Chemistry of Organic Radical
Anions), Moscow: Nauka, 1990.
Investigation of kinetics of the processes. The
kinetics of the reaction of zinc with benzyl chloride in
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 10 2012

KINETICS AND MECHANISM OF BENZYL CHLORIDE REACTION
1699
13. Golubev, V.A., Sen’, V.D., and Rozantsev, E.G., Izv.
Akad. Nauk SSSR, Ser. Khim., 1979, no. 9, p. 2091.
22. Egorov, A.M., Matyukhova, S.A., and Anisimov, A.V.,
Appl. Organometal. Chem., 2005, vol., 19, no. 5, p. 605.
23. Mezhgosudarstvennyi standart GOST 23957.1–2003,
Moscow: IPK Izd. Standartov, 2005.
24. Egorov, A.M., Matyukhova, S.A., Demidova, I.S.,
Platonov, V.V., and Proskuryakov, V.A., Zh. Prikl.
Khim., 2004, vol. 77, no. 8, p. 1346.
14. Biere, R., Lemaire, H., and Rassat, A., Bull. Soc.
Chim. France, 1965, no. 11, p. 3273.
15. Rozantsev, E.G. and Sholle, V.D., Organicheskaya
khimiya svobodnykh radikalov (Organic Chemistry of
Free Radicals), Moscow: Khimiya, 1979.
25. Mezhgosudarstvennyi standart GOST 3640–94,
Moscow: IPK Izd. Standartov, 1996.
16. Brown, W.G. and McClure, D.E., J. Org. Chem., 1970,
vol. 35, no. 6, p. 2036.
26. Svoistva organicheskikh soedinenii. Spravochnik
(Properties of Organic Compounds. Handbook),
Potekhin, A.A., Ed., Leningrad: Khimiya, 1984.
27. Gordon, A.J. and Ford, R.A., The Chemist’s Com-
panion. A Handbook of Practical Data, Techniques
and References, New York: Wiley, 1972.
28. Burwell, R.L., Shields, A.D., and Hart, H., J. Am.
Chem. Soc., 1954, vol. 76, no. 3, p. 908.
29. Giondo, G.M., Gregorio, F.D., Palladino, N., and
Marconi, W., Tetrahedron Lett., 1973, no. 34, p. 3195.
30. Bull, W.E., Madan, S.K., and Willis , J.E., Inorg.
Chem., 1963, vol. 2, no. 2, p. 303.
17. Bairamov, V.M., Osnovy khimicheskoi kinetiki i
kataliza (Fundamentals of Chemical Kinetics and
Catalysis), Moscow: Akademiya, 2003.
18. Egorov, A.M., Matyukhova, S.A., and Anisimov, A.V.,
J. Phys. Org. Chem., 2005, vol. 18, no. 5, p. 456.
19. Nifontova, G.A., Echmaev, S.B., Sikorenko, Yu.B.,
and Lavrent’ev, I.P., Zh. Fiz. Khim., 1998, vol. 72,
no. 1, p. 147.
20. Sergeeva, V.P., Kondin, A.V., Alyasov, V.N., and
Maslennikov, V.P., Kinetika i Kataliz, 1993, vol. 34,
no. 4, p. 615.
21. Blackburn, E.V. and Tanner, D.D., J. Am. Chem. Soc.,
31. Cohen, H.L. and Wright, G.F., J. Org. Chem., 1953,
vol. 18, no. 4, p. 432.
1980, vol. 102, no. 2, p. 692.
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