Kinetics and mechanism of nickel reaction with benzyl bromide in dimethylformamide

Article abstract of DOI:10.1134/S1070363209030177

Abstarct: The reaction of nickel with benzyl bromide in DMF has been studied. The reaction intermediates were investigated by different methods and the kinetic and thermodynamic parameters were determined. The reaction of benzyl bromide with nickel was shown to occur on the metal surface by the Langmuir-Hinshelwood scheme, with the formation of benzyl radicals which are recombined and isomerized in solution to form 1,2-diphenylethane and trace amounts of 4.4'-dimethylbiphenyl.

Full text of DOI:10.1134/S1070363209030177

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 3, pp. 444–452. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © A.M. Egorov, S.A. Matyukhova, I.S. Kocherova, A.A. Novikova, A.V. Anisimov, 2009, published in Zhurnal Obshchei Khimii, 2009,
Vol. 79, No. 3, pp. 455–463.
Kinetics and Mechanism of Nickel Reaction
with Benzyl Bromide in Dimethylformamide
a
a
a
a
b
A. M. Egorov , S. A. Matyukhova , I. S. Kocherova , A. A. Novikova , and A. V. Anisimov
a
Tula State University, pr. Lenina 92, 300600 Russia
b
Lomonosov Moscow State University, Moscow, Russia
e-mail: silver_sun@inbox.ru
Received September 12, 2008
Abstarct―The reaction of nickel with benzyl bromide in DMF has been studied. The reaction intermediates
were investigated by different methods and the kinetic and thermodynamic parameters were determined. The
reaction of benzyl bromide with nickel was shown to occur on the metal surface by the Langmuir-Hinshelwood
scheme, with the formation of benzyl radicals which are recombined and isomerized in solution to form 1,2-
diphenylethane and trace amounts of 4.4'-dimethylbiphenyl.
DOI: 10.1134/S1070363209030177
In the plastics industry, to prepare technically
valuable products various additives are introduced into
polymers. For example, halogenated nickel complex
compounds are effective light stabilizers for various
polymers [1].
In the present paper, the mechanism of the reaction
of nickel with benzyl bromide was studied aiming at
elaboration of the environmentally friendly technology
for preparation of the nickel complex compounds with
organic ligands without the use of carbon tetrachloride.
To study the products of the reaction, we have
performed the reaction of nickel powder with benzyl
bromide in dimethylformamide in an atmosphere of
pure dry argon at 80°С at stirring. After complete
dissolution of nickel, a complex compound hexakis(di-
methylformamide)nickel(II) bromide [Ni(DMF) ]Br ,
Nickel complex compounds are obtained in one-
step by the reaction of carbon tetrachloride with
specimens of active nickel in dipolar aprotic solvents
[
2]. Now it is established that carbon tetrachloride is an
ozone depleting compound and its industrial use is
forbidden. Therefore, it became necessary to find a
substitute for it in different chemical processes.
6
2
1,2-diphenylethane, and less than 0.1% of 4,4'-dimethy-
biphenyl were isolated from the reaction mixture:
CH2 Br + Ni + DMF
[Ni(DMF) Br +
CH2 CH2
6
2
+
H C
3
CH3
<0.1%
Using the method of ion chromatography we found
that only nickel(II) cations were present in solution,
while nickel(I) and nickel(III) were not formed in the
reaction under investigation. Analysis of the reaction
mixtures by the use of chromatomass spectrometry has
shown that 1,2-diphenylethane and trace amounts of
4,4'-dimethylbiphenyl are the only organic products of
the reaction. The molar ratio 1,2-diphenylethane:
dissolved nickel of 1:1 suggests that the reaction
products are formed not due to catalytic coupling of
benzyl bromide but by the radical mechanism, via the
formation of a radical pair [3]:
444

KINETICS AND MECHANISM OF NICKEL REACTION
445
CH +
CH2
2
H C CH2
CH2 CH2
2
H C
CH3
H C
CH3
3
3
possible to generate an asymmetric center in this place.
+)-R-1-Bromo-1-phenylethane was synthesized by the
The absence of toluene in the reaction products
allows a conclusion that in the reaction of benzyl bro-
mide with nickel in dimethylformamide the benzyl ra-
dical does not abstract hydrogen atom from the solvent.
(
known procedure [4] from the phosphoryl tribromide
and (-)-S-1-phenylethanol in the presence of pyridine
in 74% yield and 76% optical purity. In turn, (-)-S-1-
phenylethanol was prepared by asymmetric reduction
of acetophenone [5, 6]. The reaction of (+)-R-1-bromo-
1-phenylethane with nickel in dimethylformamide in
an atmosphere of pure dry argon at 80°С proceeded
with the loss of optical activity:
One of methods which allows to check the
suggestion of the radical mechanism of a reaction is
investigation of the stereochemistry of the process. The
presence of the reaction center in the methylene
fragment of the benzyl bromide molecule makes it
CH Br + Ni + DMF
CH3
[Ni(DMF) ]Br
6
2
(
+)-R
CH3
+
CH CH
CH3
+
CH CH
CH3 CH3
-
-
RR, SS 45%
RS, RS 47%
+
CH CH +
CH CH3
4%
2
4
%
All organic products were isolated by preparative
liquid chromatography and identified by different
methods. The ratio of RS,RS-2,3-diphenylbutane and
RR,RR-2,3-diphenylbutane was 1.04:1, that in
conjunction with the detection of equal amounts of
styrene and ethylbenzene is typical for reactions with
optically active 1-phenylethyl radicals [7]. Recombina-
tion and disproportionation of 1-phenylethyl radicals
occurs in solution in the cage of the solvent [8].
Identification of radical intermediates was per-
formed at 77 K in films of cocondensates of nickel
with benzyl bromide (the ratio of nickel:benzyl
bromide 1:50) according to the protocol described in
[9]. Nickel was evaporated from a corundum crucible
at 1650–1700 K, 10 torr). Nickel and benzyl bromide
were cocondensed in the regime of molecular beams
onto a quartz finger cooled to 77 K. ESR spectrum of
the cocondensate of nickel with benzyl bromide at 77 K
–
4
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009

4
46
EGOROV et al.
represents a triplet of quartets with full width ~55 G
and g-factor of ~2.002, its parameters are given in
Table 1. Comparison of the obtained spectra of
cocondensates with the literature data [9, 12, 13] on
the ESR spectrum of the benzyl radical allows to
assign these spectra to the ESR spectrum of the benzyl
radical in solid matrix; no ion-radical pairs were
detected.
formamide was 1:5:8) placed in an ampoule in the spec-
trometer resonator. The ESR spectrum of the reaction
mixture was assigned to the spectrum of the nitroxyl
radical by comparing to the literature data [16]. During
the reactions, the ESR signals of the introduced stable
radical (TMPO) disappear. Further treatment of the
reaction mixtures with hydrogen peroxide in an
alkaline medium does not lead to restoration of the
ESR signals, which is indicative of the presence of
radical intermediates in solution [14, 15].
When the cocondensates of nickel with benzyl
bromide were warmed to 120 K only the ESR signals
of the PhĊH radicals were observed, and a gradual
Investigation of the process by the ESR method in
the presence of TMPO allowed us to establish the
nature of the reaction under consideration but did not
allow to determine the nature of the radical
intermediates. The reaction of the benzyl radical with
2
decrease in the intensity of the triplet of quartets
occurred with growing temperature. At 130-150 K
further decrease in the intensity of the ESR signals and
substantial deterioration of the resolution of ESR
spectra caused apparently by overlapping of signals
dicyclohexyldeuterophosphine (Cy PD) is known to
2
.
..
from radical pairs of the PhCH CH Ph type.
proceed by the following scheme [12]:
2
2
These data allow a conclusion that nickel atoms
react with benzyl bromide with formation of the benzyl
radical by a single electron transfer mechanism with
abstraction of the halogen atom:
CH2
+
P
D
CH D +
P
2
CH2 Br + Ni
CH2 + NiBr
Therefore, we have carried out the reaction of
nickel with benzyl bromide in DMF in the presence of
In the cocondensate, the radicals are in the cage of
Cy PD:
2
solid benzyl bromide (molar ratio PhCH Br : Ni = 50:1),
2
that is why the radical Ni+Br at 77 K does not
disproportionate but rather reacts with the second
molecule of benzyl bromide by abstraction of the
halogen atom:
CH2 Br + Ni + DMF
Cy PD
2
[
Ni(DMF) ]Br +
CH D
2
6
2
CH2 Br + NiBr
CH2 + NiBr2
For the Ni:Cy PD ratio of 1:5, instead of the
2
expected 1,2-diphenylethane and 4,4'-dimethylbi-
phenyl, the equivalent amount of α-deuterotoluene was
isolated from the reaction mixtures. This is indicative
of the fact that benzyl radicals move from the metal
surface into the solution, where their recombination
and isomerization in the radical pair occur.
For detection of radical intermediates at 298 K we
used the spin trap method. As a spin trap, we used the
stable radical 2,2,6,6-tetramethylpiperidine-1-oxyl
(
TMPO) [14,15]. It was added into the reaction
mixture (the ratio nickel:benzyl bromide:dimethyl-
To determine the routes of formation of 1,2-
diphenylethane [17] we have studied the reaction of
nickel with benzyl bromide in the presence of DMF at
low temperatures by the use of high-vacuum unit for
preparation of atomic metals and cryosynthesis [18].
Cocondensation of nickel with benzyl bromide and
DMF (molar ratio 1:10:0-10, respectively) was carried
out in the regime of molecular beams onto the surface
of the reactor cooled to 77 K. First on the surface of
the reactor pink films of cocondensates were formed,
Table 1. Parameters of ESR spectrum (а/G) of the benzyl
radical in solid matrices
H
H
H
H
g-Factor
a
CH2
G
a
o
, G
a
m
, G
a
p
, G
References
a
2
2
2
.002±0.001 16.5±0.5 5.5±0.5
.002±0.001 16.4±0.5 5.5±0.5
.002±0.001 16.4±0.5 5.5±0.5
–
5.5±0.5
5.5±0.5
5.5±0.5
6.17
–
–
[9]
[12]
[13]
2
.0026
16.34
5.13
1.77
a
From the present work.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009

KINETICS AND MECHANISM OF NICKEL REACTION
447
which quickly turned colorless. Pink color of the
samples suggests the presence of π-complexes of
nickel with benzyl bromide [19]. Low melting point of
DCl allowed to perform acidolysis of the reaction
mixture both at 160 and at 298 K (Table 2):
Table 2. Reaction products found in the reaction mixtures
after their treatment with DCl at 160 and 298 K
Yield, % ± 1%
Ni:PhCH
2
Br:DMF
Т, K
a
b
PhCH
2
2
CH Ph
2
PhCH D
1
1
1
:10:0
:10:5
:10:10
160
96
99
92
98
90
98
4
1
2
98
160
98
160
98
CH2 NiBr + DCl
8
2
2
10
2
CH D + NiClBr
2
2
a
b
<
0.1% of 4,4'-dimethylbiphenyl. 2% of toluene.
To detect organonickel intermediates at 298 K, we
heated the obtained sample to 298 K; the cocondensate
melted and turned colorless. The melt formed
contained yellow inclusions. The specimen was
rate of the nickel reaction with benzyl bromide in the
absence of DMF (in benzene) is lower than the
threshold of the sensitivity of the instrument. Such a
shape of the curves is characteristic of the reactions
proceeding on the metal surface by the Langmuir-
filtered and treated with 0.1N solution of DCl in D O.
2
The analysis of yellow inclusions by the method of ion
2
+
chromatography have shown that they contain Ni and
–
Hinshelwood mechanism provided
that the
Br ions in the ratio of 1:2, that corresponds to the
components are adsorbed on the same active centers of
the metal surface [23].
molecular formula NiBr . For quantitative determina-
2
tion of organonickel compounds the obtained cocon-
densates were heated to 160 K, then cooled to 77 K,
and DCl was condensed onto the surface of the films
formed. The specimens were defrosted and filtered, the
yields of the products are given in Table 2.
K1
CH2
Br + S
CH2
Br S,
(1)
(2)
K2
DMF + S
(DMF)S,
As can be seen from Table 2, the organonickel
compounds are more stable at low temperatures.
Increase of the DMF content results in a negligible
stabilization of benzylnickelbromide. Analysis of the
gas phase showed that in no case hydrogen or its
deuterated analogs were formed in the course of
acidolysis of the reaction mixtures, which is indicative
of the absence of benzylnickelhydride intermediates in
the reaction mixture. Therefore, the main amount of
CH2 Br S + (DMF)SH
2
k3
(
3)
reaction products,
5
–2
–1
W×10 , g cm min
30
1
,2-diphenylethane is formed by recombination of
2
5
benzyl radicals in solution rather than decomposition
of organonickel compounds.
20
15
1
The kinetic parameters of the reaction were
determined by a resistometric method [12, 20, 21]
suitable for investigation of processes occurring on a
metal surface. The use of an inert solvent (benzene,
DNSbCl5 = 0.42 kJ mol [22]) allowed to obtain the
dependences of the rate of dissolution of the metal
both on concentration of benzyl bromide and of dipolar
aprotic solvent. The kinetics was studied in a wide
range of concentrations (0–7 M) at 313–353 K.
2
1
0
5
0
–
1
0
2
4
6
8
C, M
Reaction rate (W) of the reaction between nickel and
benzyl bromide in DMF as function of initial
a
concentrations of the components at 353 K in the presence
of an inert solvent (benzene): (1) c(DMF) = 0.5 M;
The rate dependences on the initial concentrations
of the components (see figure) are smooth curves with
maxima. The curves start from the origin, that is, the
2 2
c(PhCH Br) varied from 0 to 7.0 M and (2) С(PhCH Br) =
0
.5 M; c(DMF) varied from 0 to 7.0 M.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009

4
48
EGOROV et al.
where S are active surface centers on which benzyl
enthalpy and entropy of adsorption. This can be due to
a large heat evolution during the adsorption or by
interaction between the adsorbate and the metal
leading to deformation or dissociation of the adsorbed
molecules. Large negative values of the entropy of
adsorption of benzyl bromide and DMF suggest that
they do not dissociate on the nickel surface during
adsorption.
bromide and DMF are adsorbed, K and K are the
1
2
adsorption constants for adsorption of benzyl bromide
and DMF onto the metal surface, k is the rate constant
3
of the rate-determining step.
The equation for the reaction rate (W) includes the
degrees of covering of the surface obtained from the
Langmuir isotherm for adsorption of each component
and has the following form:
The detailed analysis of the obtained results shows
that the first steps of the nickel reaction with benzyl
bromide in DMF are nondissociative adsorption of the
reagent and the solvent on the same active centers of
the nickel metal surface. Apparently, benzyl bromide
is adsorbed so that the benzene ring is oriented parallel
to the surface [24–27]. Only after that, benzyl bromide
reacts with nickel with elimination of bromine and
formation of benzyl radical.
K
1
K
2
[PhCH
2
Br][DMF]
[DMF])
W = k
(4)
,
2
(
1 + K
1
[PhCH Br] + K
2
2
2
where k = KN , N is the number of active centers of
the metal surface on which benzyl bromide and DMF
are adsorbed.
To determine the rate constants k and equilibrium
constants for adsorption of benzyl bromide and DMF
on the metal surface (K and K ) the algorithm was
The second molecule of benzyl bromide attacks
Ni BrDMF (part of the nickel surface) by the
n
1
2
Langmuir–Hinshelwood or Eley–Rideal mechanism to
form the second benzyl radical and a solvated
established involving linearization of the experimental
–
1 0.5
dependencies in the coordinates (CW ) vs. f(C).
Investigation of the reaction kinetics at various
temperatures (313–353 K) provided a possibility to
molecule of NiBr (Scheme 1).
2
Benzyl radical reacts with Ni Br DMF to form
n
determine the energy of activation Е of the chemical
а
organonickel compounds.
process as well as the enthalpies and entropies of
adsorption of benzyl bromide and DMF on the nickel
surface. The Langmuir–Hinshelwood scheme for the
process under consideration suggests that the rate-
determining step is the interaction of the adsorbed
molecules of the reagents with the surface of the
oxidized metal, that is, a chemical reaction on the
surface [20, 23].
Organonickel compounds are decomposed by the
known scheme [17]. (Scheme 2)
Benzyl radicals in solution recombine with the
formation of 1,2-diphenylethane and isomerize to form
the traces of 4,4'-dimethylbiphenyl.
EXPERIMENTAL
As can be seen from Table 3, both benzyl bromide
and dimethylformamide have large negative values of
Analysis of the reaction products and quantitative
determination of admixtures in the reagents was
performed by the GC method on a Tsvet-800
chromatograph, the details were published earlier [9].
Analysis by the method of ion chromatography was
done on a Tsvet-3006 chromatograph with electro-
conductivity detector using a “Diakat-3” (Elsiko,
Moscow, l 150 mm, d 3 mm) or a “Hiks-1” column
Table 3. Kinetic and thermodynamic parameters of the
a
nickel reaction with benzyl bromide in DMF
4
–1
–1 b
–1 c
–1 d
Т, K
k×10 , g cm min
2.23±0.01
4.39±0.01
8.21±0.02
10.7±0.1
K
1
, l mol
2
K , l mol
3
3
3
3
3
3
13
23
33
38
43
53
3.12±0.03
2.39±0.01
1.93±0.01
1.72±0.01
1.51±0.01
3.08±0.01
2.44±0.01
1.99±0.01
1.77±0.01
1.64±0.01
(
Institute of Chemistry, Estonian Academy of Sciences,
particles of 15 μm size) by the earlier described
procedure [9].
15.8±0.1
1
Н NMR spectra were taken on a Jeol LTD FX-90Q
27.7±0.2
1.21±0.01
1.33±0.01
spectrometer for 25–30% solutions in deutero-
chloroform with hexamethyldisiloxane (HMDS) as an
internal reference. The accuracy of measurement of
chemical shifts was ±0.01 ppm (δ scale). IR spectra in
a
0
0
-1
E
2
a
57.8±2.5; ΔНRHal –21.5±1.0; ΔНDMF –19.1±0.7 kJ·mol ; at
0
0
–1
–1
98 K ΔSRHal –59.2±3.4; and ΔSDMF –51.7±2.3 J mol K .
Selected correlation coefficient for the dependence ln Y = f(1/T).
b
c
d
1 2
R = 0.998 (Y = k). R = 0.998 (Y = K ). R = 0.999 (Y=K ).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009

KINETICS AND MECHANISM OF NICKEL REACTION
449
Scheme 1.
CH2 Br
K1
DMF
K2
CH2
CH2 Br
Nin
DMF
CH2 Br
Nin
DMF
K
CH2 Br
Br DMF
CH2
NiBr DMF
2
+
Nin
Br DMF
Nin
CH2 Br +
CH2
NiBr DMF
2
Nin
NiBr DMF + 5 DMF
[Ni(DMF) ]Br
6 2
2
Scheme 2.
CH2
Nin
Br DMF
+
CH2
Nin
Br DMF
Br DMF
Nin
CH2
+
CH2
Nin-1
NiBr DMF
CH2 NiBr DMF
+
Nin-1
CH2 NiBr DMF + DMF
CH2 NiBr 2 DMF
2
CH2 NiBr 2 DMF + 4 DMF
CH2
NiBr 2 DMF + [Ni(DMF) ]Br2
6
2
CH2
NiBr 2 DMF
CH2 CH2
+ Ni + 2 DMF
2
CH +
CH2
2
H C CH2
CH2 CH2
2
H C
CH3
H C
CH3
3
3
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009

4
50
EGOROV et al.
–
1
the range of 400–4000 cm were taken on a IMPACT
4
(+)-R-1-Bromo-1-phenylethane was obtained by the
method described in [4] by the reaction of (–)-S-1-
phenylethanol with phosphoryl tribromide and
pyridine in pentane, and degassed by repeated freezing
and thawing under reduced pressure and stored in
ampoules in the absence of air. Yield 74%. Physico-
chemical properties of (+)-R-1-bromo-1-phenylethane
correspond to those in the literature [4]. (–)-S-1-
Phenylethanol was synthesized by the procedure
described in [5, 6] by the reaction of acetophenone
with (+)-S-1-(methylamino)-1-phenylethane-N-alumi-
num hydride in diethyl ether at –71°С. Yield 55%.
Physicochemical properties of (–)-S-1-bromo-1-phenyl-
ethanol correspond to those in the literature [5, 6].
00d (NICOLET) spectrophotometer in KBr.
Organic products of the reaction were isolated by
preparative liquid chromatography on a Tsvet-304
chromatograph equipped with UV detector and steel
column (l 2.5 m, d 4 mm); stationary phase Silasorb
00 (Chemapol, Czechia, size of particles 15–25 μm),
eluent hexane–diethyl ether 5:1.
6
ESR spectra of the reaction mixtures were taken on
a Radiopan SE/Х-2543 spectrometer (9400 MHz) at 77
K in films of cocondensate of nickel with 50-100-fold
excess of benzyl bromide by the procedure described
in [9] and at 293 K by the procedure from [14, 15].
2
,2,6,6-Tetramethylpiperidyl-1-oxyl was used as a
Nickel complex compounds were prepared by the
following procedures. To 0.02 M of nickel powder
stable radical [14].
2
0 ml of DMF and 0.1 mol of benzyl bromide was
Specific rotation of the polarization plane was
measured on an automatic polarimeter VNIIEKI
prodmash А-1 EPO (σ 0.01) in cells of different width.
added at 70°С in a dry argon atmosphere. After dis-
solution of nickel, the reaction mixture was treated
with 20 ml of dry diethyl ether. The precipitated
crystals of the nickel(II) complex compound were
separated, washed with hexane and dried in vacuum.
Chromatomass analysis of the reaction products
was performed on a Hewlett Packard instrument
(
5
USA) (mass detector НР-5972, chromatograph НР-
890) by the earlier described procedure [12, 23].
[
Ni(DMF) ]Br . Yield 82 %. Found (%): C 32.92, H
6 2
6.48, Br 24.35, N 12.77, Ni 8.90, O 14.57. C H ·
18 42
Quantitative analysis of admixtures in nickel was done
Br N NiO . Calcd (%): C 32.90, H 6.44, Br 24.32, N
2
6
6
–1
after dissolution of the metal specimens in HNO and
3
12.79, Ni 8.93, O 14.62. IR spectrum, ν, cm : 425
neutralization of the obtained solution with 25%
aqueous ammonia by atomic absorption spectrometry
method on a GBC-908 АА instrument (Australia).
(
(
(
(
Ni–O), 465 (Ni–O), 690 (OCN), 1030 (СН ), 1070
СН ), 1120 (СН ), 1160 (СН ), 1255 (С-N), 1387
СН ), 1425 (СН ), 1445 (СН ), 1635 (C=O Ni), 1650
C=O Ni) (KBr).
3
3
3
3
…
3
3
3
…
Nickel powder of GOST 9722-79, with nickel
–
4
content of 99.8405%±2×10 %, trademark PNE-1
Lux” (FSUE Ural electrochemical complex, RF) was
used. Nickel wire (NI005106 Goodfellow Corporation,
In ether solution the unreacted benzyl bromide and
“
DMF as well as 1,2-diphenylethane and 4,4'-dimethyl-
biphenyl were detected by chromatomass spectrometry.
–4
USA, Ni 99.9804%±2×10 %) of 0.025 mm diameter
and 10 mm length was placed for 5–10 s in 20%
sulfuric acid solution, washed with water, acetone and
DMF (all operations were carried out in an inert gas
atmosphere). All organic compounds are commercially
available. Benzyl bromide (Aldrich) was dried over
The reaction in the presence of a radical trap was
investigated in a similar way as the preparation of
nickel complex compounds. Cy PD was used as a
2
radical trap. After sedimentation of the precipitate, in
ether solution the unreacted DMF and benzyl bromide
as well as α-deuterotoluene were detected by chro-
matomass spectrometry.
calcined CaCl and distilled, bp 83.5–84°С (32 mm Hg),
2
2
0
20
n
1.4380. {bp 83.5–84°С (32 mm Hg), nD 1.4380
D
[
28]}. DMF was purified by double slow vacuum
The stereochemistry of the reaction was studied in a
similar way as the preparation of nickel complex
compounds. (+)-R-1-Bromo-1-phenylethane was taken
as an organyl halide. After sedimentation of the
precipitate, in ether solution the unreacted DMF and
distillation over large amount of P O [29], then
2
5
refluxed for 2 h over calcium hydride and distilled in a
vacuum under nitrogen. Acetone, diethyl ether, and
other solvents were purified by conventional
procedures [30]. Benzyl bromide and all solvents were
degassed by repeated freezing and thawing under
reduced pressure and stored in ampoules in the absence
of air.
(
+)-R-1-bromo-1-phenylethane were detected by
chromatomass spectrometry, and also RR-,SS-2,3-
diphenylbutane, RS-,RS-2,3-diphenylbutane, styrene
and ethylbenzene were isolated and identified. The
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009

KINETICS AND MECHANISM OF NICKEL REACTION
451
yields of the reaction products are presented in the
scheme in the Results and Discussion section, physico-
chemical properties of the isolated compounds
correspond to those in the literature [28, 31, 32].
As an inert solvent for determination of kinetic
characteristics of the nickel reaction with benzyl
bromide in the presence of DMF benzene was chosen
[22].
The reaction of atomic nickel with the system
benzyl bromide–DMF was performed in a high-
vacuum unit for generation of atomic metals and
cryosynthesis [18]. 1 g of compact metal produced by
vacuum melting (1650–1700 K, 0.1 torr) of nickel
metal, evaporated from a corundum crucible (1650–
ACKNOWLEDGMENTS
This work was financially supported by the
Program of the Ministry of Education and Science of
RF “Basic Research in High School in Natural and
Humanitarian Sciences. Universities of Russia,” grants
nos. UR.05.01.012 and UR.05.01.419.
–4
1700 K, 10 torr) and in the regime of molecular
beams cocondensed with the system benzyl bromide–
DMF in the molar ratio 1:10:(0–10) on the surface of
the reactor cooled to 77 K by liquid nitrogen. The rate
REFERENCES
–
1
of nickel evaporation was 0.2 mmol min , the duration
of cocondensation 2–4 h. The specimens first turned
pink, then became colorless.
1
2
. Maskiya, L., Dobavki dlya plasticheskikh mass
(Addition for Plastmasses), Moscow: Khimiya, 1978.
. Garnovskii, A.D., Kharisov, B.I., Gojon-Zorilla, G., and
Garnovskii, D.A., Russ. Chem. Rev. Engl. Transl., 1995,
vol. 64, no. 3, p. 201.
Acidolysis of cocondensates at 160 K. The ob-
tained cocondensates were heated to 160 K, kept at this
temperature for 20 min, then cooled again to 77 K. On
the surface of the prepared films gaseous DCl (50 g)
was condensed. Upon heating above 160 K the
cocondensate melted and turned colorless with yellow
inclusions.
3
. Bagdasar’yan, K.S., Kirjukhin, Yu.I., and Sinitsyna, Z.A.,
Khim. Fizika, 1982, no. 12, p. 1666.
4
5
. Dauben, H.J. and McCoy, L.L., J. Am. Chem. Soc.,
959, vol. 81, no. 20, p. 5404.
1
. Giondo, G.M., Gregorio, F.D., Palladino, N., and
Marconi, W., Tetrahedron Lett., 1973, no. 34, p. 3195.
Acidolysis of cocondensates at 298 K. When
cocondensation was completed, the reactor was
charged with pure dry argon and allowed to warm; the
cocondensate melted at 269 K and turned light-yellow
with solid yellow inclusions. The specimen was
filtered, to the melt of cocondensate 0.1N solution of
6. Egorov, A.M. and Anisimov, A.V., J. Organometal.
Chem., 1994, vol. 479, no. 1, p. 197.
7. Brown, W.G. and McClure, D.E., J. Org. Chem., 1970,
vol. 35, no. 6, p. 2036.
8
. Green, F.D., Berwick, M.A., and Stonell, J.C., J. Am.
Chem. Soc., 1970, vol. 92, no. 4, p. 867.
DCl in D O was added. From the obtained solution a
precipitate sedimented, which was separated and
analyzed by the method of ion chromatography.
2
9. Egorov, A.M. and Anisimov, A.V., Appl. Organomet.
Chem., 1995, vol. 9, nos. 1, 2, p. 285
1
0. Sergeev, G.B., Smirnov, V.V., and Zagorsky, V.V.,
Vestn. Mosk. Univ. Ser. 2: Khimiya., 1980, vol. 21, no. 3,
p. 257.
After separation of the precipitate, in the melt of the
cocondensate, along with DMF and benzyl bromide,
1
1
1
1
1
1
1. Egorov, A.M. and Anisimov, A.V., Russ. J. Org. Chem.
Engl. Transl., 1998, vol. 34, no. 1, p. 68.
1
,2-diphenylethane, traces of 4,4'-dimethylbiphenyl,
and small amounts of α-deuterotoluene were detected
by the method of chromatomass spectrometry. The
yields of the products are given in Table 2.
2. Egorov, A.M., Matyukhova, S.A., and Anisimov, A.V.,
J. Phys. Org. Chem., 2005, vol. 18, no. 5, p. 456.
3. Neta, P. and Schuler, R.N., J. Phys. Chem., 1973, vol. 77,
no. 11, p. 1368.
4. Letuchii, Ya.A., Lavrent’ev, I.P., and Hidekel, M.L.,
Koord. Khim., 1982, vol. 8, no. 11, p. 1477.
5. Golubev, V.A., Sen’, V.D., and Rozantsev, E.G., Izv.
Akad. Nauk SSSR. Ser. Khim., 1979, no. 9, p. 2091.
6. Biere, R., Lemaire, H., and Rassat, A., Bull. Soc. Chim.
France., 1965, no. 11, p. 3273.
17. Matsumoto, H., Inaba, S.-I., and Rieke, R.D., J. Org.
Chem., 1983, vol. 48, no. 6, p. 840.
Kinetic studies. Investigation of the kinetics of the
nickel reaction with benzyl bromide in DMF was
performed by resistometric method [12, 20, 21] using
the known procedure [21] in the atmosphere of dry,
oxygen free argon. The rate of the stirrer rotation was
2
500 rpm. Starting from 2000 rpm, the rate of
dissolution of nickel in the studied media did not
depend on the rate of stirring, that was indicative of
kinetic regime of the process.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009

4
1
52
EGOROV et al.
8. Moskovits, M. and Ozin, G., Kriokhimiya, Moscow:
Mir, 1979.
25. Morgenstern, K., Hla, S.-W., and Rieder, K.-H., Surf.
Sci., 2003, vol. 523, nos. 1–2, p. 141.
1
2
9. Hartman, I.S. and Kelusky, E.C., Can. J. Chem., 1982,
vol. 60, no. 21. p. 2654.
0. Sergeeva, V.P., Kondin, A.V., Aljasov, V.N., and
Maslennikov, V.P., Kinet. Katal., 1993, vol. 34, no. 4,
p. 615.
1. Nifontova, G.A., Echmaev, S.B., Sikorenko, Yu.B., and
Lavrent’ev, I.P., Russ. J. Phys. Chem., A., 1998,
vol. 72, no. 1, p. 134.
2. Gutman, V., Khimiya koordinatsionnykh soedinenii v
nevodnykh rastvorakh (Chemisry of Coordination
Compounds in Non-Aqueous Solutions), Moscow: Mir,
26. Xi, M. and Bent, B.E., J. Am. Chem. Soc., 1993,
vol. 115, no. 16, p. 7426.
27. Ma, Z. and Zaera, F., Surf. Sci. Rep., 2006, vol. 61, no. 5,
p. 229.
2
8. Svoistva organicheskikh soedinenii. Spravochnik
(Properties of Organic Compounds. Handbook),
Potekhin, A.A., Ed., Leningrad: Khimiya, 1984. 286 p.
2
2
2
3
9. Artamkina, G.A., Beletskaya, I.P., and Reutov, O.A.,
Zh. Org. Khim., 1973, vol. 9, no. 9, p. 1769.
0. Gordon, A.J. and Ford, R.A., The Chemist’s Com-
panion. A Handbook of Practical Data, Techniques and
References, New York: Wiley, 1972.
1
971.
2
2
3. Egorov, A.M., J. Phys. Org. Chem., 2006, vol. 19,
no. 10, p. 664.
4. Pettersson, L.G.M., Agren, H., Luo, Y., and Triguero, L.,
Surf. Sci., 1998, vol. 408, nos. 1–3, p.1.
3
3
1. Cohen, H.L. and Wright, G.H., J. Org. Chem., 1953,
vol. 18, no. 4, p. 432.
2. Khalaf, A.A. and Roberts, R.M., J. Org. Chem., 1966,
vol. 31, no. 3, p. 926.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009