Reduction of halogen-containing hydrocarbons with diisobutylaluminum hydride, catalyzed by LnCl3·3H2O·3(EtO) 2AlOH complexes

Full text of DOI:10.1134/S1070428006100290

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2006, Vol. 42, No. 10, pp. 1570–1572. © Pleiades Publishing, Inc., 2006.
Original Russian Text © R.G. Bulgakov, S.P. Kuleshov, D.S. Karamzina, U.M. Dzhemilev, 2006, published in Zhurnal Organicheskoi Khimii, 2006, Vol. 42,
No. 10, pp. 1581–1582.
SHORT
COMMUNICATIONS
Reduction of Halogen-Containing Hydrocarbons
with Diisobutylaluminum Hydride, Catalyzed
by LnCl ·3H O·3(EtO) AlOH Complexes
3
2
2
R. G. Bulgakov, S. P. Kuleshov, D. S. Karamzina, and U. M. Dzhemilev
Institute of Petroleum Chemistry and Catalysis, Russian Academy of Sciences,
pr. Oktyabrya 141, Ufa, 450075 Bashkortostan, Russia
e-mail: ink@anrb.ru
Received May 31, 2006
DOI: 10.1134/S1070428006100290
The problem of reductive dehalogenation of halo-
genated hydrocarbons can be divided into two main
parts. The first of these is concerned with complete de-
halogenation via catalytic hydrogenation [1], which is
important for utilization of organohalogen wastes. The
second part includes partial dehalogenation to obtain
commercially valuable products, for example, reduc-
tion of dihalocyclopropanes to monohalocyclopro-
panes which are used in the synthesis of multipurpose
cyclopropenes [2]. An effective dehalogenation proce-
dure is based on the reduction of aryl or alkyl halides
with accessible diisobutylaluminum hydride in the
presence of transition metal complexes (Ti, V, Mn, Fe,
Co, Ni, Zr, Mo, Ru, Rh, Pd, Hf, W) [3–5]. The cata-
lytic activity of lanthanide compounds in the dehalo-
genation processes was not studied previously [1, 6].
halides with (i-Bu) AlH. As catalysts we used lantha-
2
nide complexes of the general formula LnCl ·3H O·
3
2
3(EtO) AlOH (where Ln = Ce, Nd, Eu, Tb, Ho; herein-
2
after referred to as [Ln]); their preparation by reaction
of LnCl ·6H O with Al(OEt) was described in [7].
3
2
3
The examined [Ln] catalysts turned out to be highly
selective and fairly effective (see table). Thus the con-
version of chlorobenzene over [Tb] was 60%, while
the known catalyst, (BuO) Ti, ensured only 35% con-
4
version [3]. Using bromobenzene as model substrate,
we examined how the conversion (%) depends on the
lanthanide nature and obtained the following series:
Ce (16) < Nd (42) < Tb (80) > Eu (28) > Ho (26). The
maximal conversion was observed in the presence of
the terbium catalyst [Tb]; it increased according to the
known C–Hlg bond energy series: Cl > Br > I.
The present communication reports for the first
time on the efficiency of lanthanide catalysts in the re-
ductive dehalogenation of halocyclopropanes and aryl
In the reduction of chloro- and bromobenzenes, the
reaction mixture contained hexane in addition to ben-
zene as the major product (see table). This result was
Ph
Br
Br
Ph
Ph
Br
Ph
(
i-Bu) AlH, [Tb]
2
+
+
Br
I
II
III
Y
Y
X4
X1
X2
(
i-Bu) AlH, [Tb]
2
X3
IVa–IVd
Va–Vd
1
2
3
4
1
2
3
4
3
1
2
4
X = Cl, Br, I, X = X = X = Y = H (a); X = X = X = X = Cl, Y = OH (b); Y = BrC
6
H
4
, X = Br, X = X = X = H (c); Y = Ph,
3
1
2
4
X = Br, X = X = X = H (d).
1570

REDUCTION OF HALOGEN-CONTAINING HYDROCARBONS
1571
unexpected, for opening of carbocycles in catalytic
hydrogenation usually occurs at higher temperature
Reduction of halogenated hydrocarbons with (i-Bu)
2
AlH in
the presence of TbCl ·3H O·3(EtO) AlOH in dioxane
3
2
2
(
150–180°C) [8]. We presumed that hexane is formed
Conversion,
%
through a series of consecutive transformations by the
action of [Tb] and (i-Bu) AlH: halobenzene → ben-
zene → cyclohexane → hexane. In fact, cyclohexane
was found to react with the system [Tb]–(i-Bu) AlH
under relatively mild conditions (80°C) to give hexane
with a conversion of 67%.
In the dehalogenation of 1,1-dibromo-2-phenyl-
cyclopropane, [Tb] was less active (conversion 64%)
than the most efficient catalyst (BuO) Ti (conversion
9
Initial compound
Reduction products
2
C
6
C
6
C
6
H
H
H
5
5
5
Cl
Br
I
060
080
100
C
6
C
6
C
6
H
H
H
6
6
6
+ hexane, 4:1
+ hexane, 3:1
2
2,3,4,6-Tetrachloro-
phenol
0
0
53
64
C
6
H
5
OH
1,1-Dibromo-2-phenyl-
cyclopropane
II + I + III, 2:1.5:1
p-C H C H Br
4
8%). On the other hand, [Tb] was more selective: the
p-BrC H C H Br
100
005
6
4
6
4
6
5
6
4
ratio of the most important products, cis- and trans-1-
p-C
6
H
5
C
6
H
4
Br
6 5 6 5
C H C H
bromo-2-phenylcyclopropanes, to phenylcyclopropane
was 3.5:1 against 1:3 in the presence of (BuO) Ti.
3
2
1
4
trum, δ , ppm: 14.15 t (C ), 22.04 d (C ), 23.99 d (C ),
C
5
9
7
6
8
Simpler salts like LnCl and LnCl ·6H O, com-
3
3
2
125.89 d (C , C ), 126.71 d (C ), 128.47 d (C , C ),
4
plexes LnCl ·3TBP, and aluminum alkoxides Al(OR)
3
3
1
37.05 s (C ).
trans-1-Bromo-2-phenylcyclopropane. H NMR
spectrum, δ, ppm: 2.93 m (1H, CH), 1.66 m (2H, CH),
(
R = Et, i-Bu) showed poor catalytic activity in the
1
dehalogenation of bromobenzene (conversion ≤15%).
Therefore, we presumed that the most active catalysts
in the dehalogenation process, as well as in the poly-
merization of dienes [9], are those possessing two
different metal ions (i.e., Ln and Al) as catalytically
active centers.
1
3
2
.48 m (3H, CH ), 7.41 m (5H, H ). C NMR spec-
2 arom
3
2
1
trum, δ , ppm: 18.88 t (C ), 21.59 d (C ), 26.83 d (C ),
C
7
5
9
6
8
1
1
26.45 d (C ), 127.86 d (C , C ), 128.47 d (C , C ),
4
39.72 s (C ).
1
13
The H and C NMR spectra were recorded on
a JEOL FX 90Q spectrometer using CDCl as solvent
Complex LnCl ·3H O·3(EtO) AlOH. A solution
3
2
2
of 0.75 mmol of Al(OEt) in 5 ml of dioxane was
3
3
and TMS as internal reference. GLC analysis was per-
formed on a Tsvet 500M chromatograph equipped with
a flame-ionization detector and a steel column, 2 m×
mm, packed with 5% of SE-30 on Chromaton
N-AW-HMDS; oven temperature programming from
0 to 270°C at a rate of 8 deg/min. The concentration
of Ln was determined by spectrofluorimetry [10, 11],
the concentration of Al , by complexometry [12], and
that of water, according to Fischer.
added under argon to 0.25 mmol of LnCl ·6H O, and
3
2
the mixture was stirred until the crystals of LnCl3·
H O disappeared (the mixture turned visually homo-
6
2
3
geneous). Separation of the mixture in a centrifuge
gave a gel which was washed with dioxane and dried
under reduced pressure (10 mm) for 20 min (until
a free-flowing powder was obtained). Found, %:
C 20.44; H 5.62; Al 11.05; Cl 14.28; Tb 21.87.
C H Al Cl O Tb. Calculated, %: C 19.96; H 5.40;
5
3
+
3
+
1
2
39
3
3
12
Al 11.23; Cl 14.76; Tb 22.03.
REFERENCES
Reduction of halogenated hydrocarbons (typical
procedure). A solution of 0.24 mmol of Al(OEt) in
3
1
2
. Zanaveskin, L.N., Aver’yanov, V.A., and Treger, Yu.A.,
Usp. Khim., 1996, vol. 65, p. 667.
1
0
2.5 ml of dioxane was added under argon to
.08 mmol of LnCl · 6 H O, and the mixture was
3
2
. Yanovskaya, L.A., Dombrovskii, V.A., and Khusid, A.Kh.,
Tsiklopropany s funktsional'nymi gruppami (Functional-
ized Cyclopropanes), Moscow: Nauka, 1980, p. 223.
. Dzhemilev, U.M. and Gaisin, R.L., Izv. Akad. Nauk SSSR,
Ser. Khim., 1988, p. 2332.
. Dzhemilev, U.M., Gaisin, R.L., Turchin, A.A., Khaliko-
va, N.R., Baikova, I.P., and Tolstikov, G.A., Izv. Akad.
Nauk SSSR, Ser. Khim., 1990, p. 1080.
. Dzhemilev, U.M., Gaisin, R.L., Turchin, A.A., and Tol-
stikov, G.A., Izv. Akad. Nauk SSSR, Ser. Khim., 1991,
p. 2084.
stirred until it became homogeneous. Halogenated
hydrocarbon, 4.8 mmol, and (i-Bu) AlH, 7.2 mmol
2
(
28.8 mmol in the reduction of tetrachlorophenol),
3
4
were added, and the mixture was heated for 6 h at
8
1
0°C, cooled to 10°C, decomposed by treatment with
5 ml of 10% hydrochloric acid, and extracted with
diethyl ether. The extract was dried over Na SO .
2
4
1
cis-1-Bromo-2-phenylcyclopropane. H NMR
spectrum, δ, ppm: 3.23 m (1H, CH), 1.27 m (2H, CH),
5
13
2
.16 m (3H, CH ), 7.01 m (5H, H ). C NMR spec-
2 arom
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 42 No. 10 2006

1
572
BULGAKOV et al.
6
7
. Lunin, V.V. and Lokteva, E.S., Izv. Ross. Akad. Nauk, Ser.
Khim., 1996, p. 1609.
. Bulgakov, R.G., Kuleshov, S.P., Karamzina, D.S., Makh-
mutov, A.R., Vafin, R.R., Shestopal, Ya.L., Mullagali-
ev, I.R., Monakov, Yu.B., and Dzhemilev, U.M., Kinet.
Katal., 2006, vol. 47, p. 760.
. Vol’pin, M.E., Akhrem, I.S., Reznichenko, S.V., and
Grushin, V.V., J. Organomet. Chem., 1987, p. 109.
. Monakov, Yu.B. and Tolstikov, G.A., Kataliticheskaya
polimerizatsiya 1,3-dienov (Catalytic Polymerization of
10. Panyushin, V.T., Afanas’ev, Yu.A., Khanaev, E.I., and
Garnovskii, A.D., Lantanoidy. Prostye i kompleksnye
soedineniya (Lanthanides. Simple and Coordination
Compounds), Rostov-on-Don: Rostov. Gos. Univ.,
1
980, p. 296.
11. Bulgakov, R.G., Kuleshov, S.P., Zuzlov, A.N., Mulla-
galeev, I.R., Khalilov, L.M., and Dzhemilev, U.M.,
J. Organomet. Chem., 2001, p. 56.
8
9
12. Charlot, G., Les Méthodes de la Chimie Analytique.
Analyse Quantitative Minérale, Paris: Masson, 1961,
4th ed., p. 965.
1
,3-Dienes), Moscow: Nauka, 1990, p. 104.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 42 No. 10 2006