Bromination of 2,2'-bipyridile

Article abstract of DOI:10.1134/S1070428006080161

A simple and convenient procedure was developed for the synthesis of 5,5'-dibromo-2,2'-bipyridyl providing the target compound in a high yield without the chromatographic separation of the reaction mixture. Polybromo derivatives of 2,2'-bipyridyl were isolated and characterized for the first time. Nauka/Interperiodica 2006.

Full text of DOI:10.1134/S1070428006080161

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2006, Vol. 42, No. 8, pp. 1200-1202. Ó Pleiades Publishing, Inc. 2006.
Original Russian Text ÓA.B. Zdravkova, N.N. Khimich, 2006, published in Zhurnal Organicheskoi Khimii, 2006, Vol. 42, No. 8, pp. 1219-1221.
Bromination of 2,2'-Bipyridile
a
b
A.B. Zdravkov and N.N. Khimich
aSt. Petersburg State University, St. Petersburg, Russia
bGrebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences, St. Petersburg,199155 Russia
e-mail: Khimich@isc.nw.ru
Received July 12, 2005
Abstract—A simple and convenient procedure was developed for the synthesis of 5,5'-dibromo-2,2'-bipyridyl
providing the target compound in a high yield without the chromatographic separation of the reaction mixture.
Polybromo derivatives of 2,2'-bipyridyl were isolated and characterized for the first time.
DOI: 10.1134/S1070428006080161
2
,2'-Bipyridyl and its derivatives are used in preparation
former two have significant drawbacks: the nitro
derivatives form in low yields [10, 11], and the sulfonation
is poorly reproducible [12, 13]. In this connection the
bromination seems much more promising, and besides
the recently developed methods of direct bromine
substitution in mono- and dibromo derivatives of 2,2'-
bipyridyla by an ester [14] and ethynyl [15] groups
essentially raise the synthetic importance of the
bromination. The bromination of 2,2'-bipyridyl was first
carried out in 1938 by two methods: by direct heating of
the components at 500°C, and by analogous reaction of
of transition metals bis-, tris-, and tetrakis(2,2'-bipyridyl)
complexes possessing interesting photophysical, photo-
chemical, and electrochemical properties [1–3]. The
practical application of the mentioned complexes involves
their insertion into a polymeric (organic or inorganic)
matrix [4, 5]. The optical nanohybride materials formed
(
films, fibers, sol-gel glasses etc.) have a strength and
a stability sufficient for their application only when the
components of the system are mutually bound. The
problem of the chemical binding of the complex to the
polymer matrix can be solved if one of the ligands in the
complex contains the 2,2'-bipyridyl with a reactive func-
tional group.
2
[
,2'-bipyridyl hydrobromide in bromine vapor at 250°C
16]. Thus Burstall believed to prepare for the first time,
although in a very low yield, 5- and 6-monobromo- and
,5'- and 6,6'-dibromo-2,2'-bipyridyls.Amodern modifica-
5
Several methods are described for preparation of such
compounds. The first procedure consists in the synthesis
of substituted 2,2'-bipyridyl from 2-bromopyridines as
developed by Fried and Elderfield [6]. However this
reaction permits only the preparation of dialkyl derivatives
in a very small yield. The modern modification of the
Fried–Elderfield reaction, Negishi synthesis [7–9]
provides a possibility to synthesize alkyl-, aryl-, ethynyl-,
carboxy-, alkoxy-, and nitrile derivatives in high yields
tion of 2,2'-bipyridyl hydrobromide bromination was
developed in 1995 [17]. It was shown that bromine atoms
replaced the hydrogen only in the positions 5 and 5'; here
the 5- and 5,5'-substituted compounds were isolated in
40–50% yields. The essential disadvantage of this process
is its laboriousness. The 2,2'-bipyridyl hydrobromide is
obtained by the reaction of 2,2'-bipyridyl with anhydrous
gaseous HBr; the developed workup of the reaction
mixture is relatively complicated, and the main separation
and purification procedure for the reaction products is
column chromatography. Therefore the goal of the
present work was the optimization of all synthesis stages
for preparation of 5,5'-dibromo-2,2'-bipyridyl starting with
obtaining the 2,2'-bipyridyl hydrobromide, through workup
of the reaction mixture to isolation of the reaction product
in an analytically pure state without subjecting it to
chromatography. We also demonstrated that at raising
(
55–90%) but this method has a considerable dis-
advantage: It is labor-consuming. Besides some reagents
used in the synthesis are expensive and difficultly
available.
One more approach involves a substitution of a C–H
bond in the 2,2'-bipyridyl proper. Three methods of
introducing substituents into 2,2'-bipyridyl are known
nowadays: nitration, sulfonation, and bromination. The
1200

BROMINATION OF 2,2'-BIPYRIDILE
1201
the reaction temperature and time occurred further
bromination of 5,5'-dibromo-2,2'-bipyridyl, and thus we
for the first time isolated and characterized polybromo
derivatives of 2,2'-bipyridyl.
maintained in a pressure reactor of stainless steel with
the Teflon lining. The reaction time and temperature is
given on the scheme. The cooled molten product was
recrystallized from 40 ml of boiling DMF. The crystals
and filtrate obtained on cooling were neutralized with
a aqueous-alcoholic KOH solution and worked up as
described further.
%
U
%
U
1
1
ꢁ
ꢂꢃꢁꢄꢅKꢆ ꢈꢉꢅKꢆ
1
1
5
-Bromo-2,2'-bipyridyl (IIa) was obtained from
18 g (56.6 mmol) 2,2'-bipyridyl hydrobromide and 20 g
0.125 mmol) of bromine. The crystals obtained by the
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,
,D
,,E
(
1
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general procedure were dissolved in 15 ml of DMF and
reprecipitated with 60 ml of ethanol to obtain 3.8 g (21%)
of analytically pure 5,5'-dibromo-2,2'-bipyridyl. Filtrate
ꢀ+%U
1
ꢀ
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,
(
DMF–ethanol) was diluted with a three-fold volume of
%
U
%U
%
U
%U
%U
water, the separated crystals were filtered off to obtain
2.7 g (20%) of analytically pure compound IIa.
%
U
1
%
U
1
1
1
%U
%U
5,5'-Dibromo-2,2'-bipyridyl (IIb) was obtained
from 12 g (37.7 mmol) of 2,2'-bipyridyl hydrobromide and
%
U
%
U
,
,F
,,G
2
0 g (125 mmol) of bromine. The crystals obtained were
dissolved in 15 ml of DMF and reprecipitated with 60 ml
of ethanol to obtain 6.35 g (53.6%) of analytically pure
compound IIb.
The structure of the newly synthesized bromides was
1
13
established by means of H and C NMR spectroscopy,
and the composition was confirmed by elemental analysis.
5
,5',6-Tribromo-2,2'-bipyridyl (IIc) was obtained
from 5 g (15.6 mmol) of 2,2'-bipyridyl hydrobromide and
5 g (93.8 mmol) of bromine. To the filtrate obtained by
1
The melting points and H NMR spectra of mono- and
dibromides obtained were consistent with the published
data [17].
1
the general procedure was added 300 ml of water. The
crystals formed were filtered off and subjected to column
chromatography. The isolated product was twice
EXPERIMENTAL
1H and 13C NMR spectra were registered on
a spectrometer Bruker DPX-300 (at 300.13 and
recrystallized from toluene.Yield 280 mg (4.5%), mp 175–
1
1
77°C. H NMR spectrum (CDCl ), d, ppm: 7.95 d.d
3
5
2
62
(
1H, H , J 2.5, J 8.5 Hz), 8.01 d (1H, H , J 8.5 Hz),
7
5.5 MHz respectively) from solutions of compounds in
1 2
5
6
1
3
8.24 d (1H, H , J 8.5 Hz), 8.30 d (1H, H , J 8.5 Hz),
DMSO-d or CDCl , internal reference TMS. C NMR
6
3
3
'
13
spectrum of perbromide IId was registered in concn.
H SO , internal reference DMSO-d . Elemental analysis
8.71 d (1H, H , J 2.5 Hz). C NMR spectrum (CDCl3),
d, ppm: 121.1, 122.5, 123.0, 124.4, 140.1, 142.9, 143.3,
150.8, 152.7, 154.8. Found, %: C 30.65; H 1.49; N 7.07.
C H Br N . Calculated, %: C 30.55; H 1.28; N 7.13.
2
4
6
was carried out on a CHN analyzer Hewlett Packard
85B. The bromine content in perbromo-2,2'-bipyridyl
was determined by Scheniger burn/titration method
titration with solution of mercury(II) nitrate]. The purity
of compounds obtained was checked by TLC on Silica
Gel 60 F254 plates. The separation by column chromato-
graphy was performed using silica gel L40/60 (40–
1
1
0
5
3
2
Perbromo-2,2'-bipyridyl (IId) was obtained from
g (12.5 mmol) of 2,2'-bipyridyl hydrobromide and 20 g
125 mmol) of bromine. The crystals obtained were twice
[
4
(
recrystallized from toluene. Yield 0.9 g (7.5%). To the
neutralized filtrate was added 300 ml of water. The
separated precipitate was filtered off, dissolved in 30 ml
of chloroform and reprecipitated into 60 ml of ethanol.
The precipitate was twice recrystallized from toluene.
Thus were obtained 5 g more of perbromo-2,2'-bipyridyl
6
0 mm).
2,2'-Bipyridyl hydrobromide (I). To 40 ml of solu-
tion of 10 g (64 mmol) of 2,2'-bipyridyl in methanol was
added 29 g (2.2 equiv) of 40% water solution of HBr.
The solvent was distilled off in a vacuum, the residue
was dried at 120°C for 12 h. Yield 20.08 g (98%).
13
(
overall yield 50%), mp 303–305°C. C NMR spectrum
(
H SO ), d, ppm: 128.4, 136.8, 138.7, 139.7, 155.8. Found,
2
4
General bromination procedure for 2,2'-bipyridyl.
%: C 15.68; Br 81.12; N 3.19. C Br N . Calculated, %:
10 8 2
A mixture of 2,2'-bipyridyl hydrobromide and bromine was
C 15.25; Br 81.19; N 3.56.
RUSSIAN JOURNALOF ORGANIC CHEMISTRYVol. 42 No. 8 2006

1202
ZDRAVKOV, KHIMICH
6
. Fried, J. and Elderfield, R.C., J. Org. Chem., 1941, vol. 6,
p. 567.
The authors are grateful to E.G. Rumyantseva for
performing the elemental analyses.
7. Smith,A.P.,Savage,S.A., Love, J.C., and Fraser, C.L., Org.
The study was carried out under a financial support
of the Russian Foundation for Basic Research (grant no.
6-03-33002-a).
Synth., 2002, vol. 78, p. 51.
8. Lutzen,A. and Hapke, M., Eur. J. Org. Chem., 2002, p. 2292.
0
9. Lutzen,A. and Hapke, M., Eur. J. Org. Chem., 2003, p. 3948.
1
0. Haginiva, J., J. Pharm. Soc. Jpn., 1955, vol. 75, p. 731.
11. Maerker, M. and Case, F.H., J. Am. Chem. Soc., 1958,
vol. 80, p. 2745.
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