Catalytic activity of iron(III), aluminum(III cobalt(II), and magnesium(II) chloride crystal hydrates in the condensation of aniline with butyraldehyde

Full text of DOI:10.1134/S1070428009060268

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 6, pp. 944–945. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © R.G. Bulgakov, S.P. Kuleshov, R.R. Vafin, U.M. Dzhemilev, 2009, published in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 6,
pp. 956–957.
SHORT
COMMUNICATIONS
Catalytic Activity of Iron(III), Aluminum(III),
Cobalt(II), and Magnesium(II) Chloride Crystal Hydrates
in the Condensation of Aniline with Butyraldehyde
R. G. Bulgakov, S. P. Kuleshov, R. R. Vafin, 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 November 14, 2008
DOI: 10.1134/S1070428009060268
Quinoline and its derivatives are used as starting
compounds in the synthesis of cyanine dyes, as ex-
tractants, sorbents, and corrosion inhibitors [1]. Lan-
thanide chloride crystal hydrates LnCl3 ·6H2O are
known to be the most effective catalysts in the synthe-
sis of alkyl-substituted quinolines via condensation of
aniline with aliphatic aldehydes [2]. Unlike anhydrous
lanthanide chlorides LnCl3 and coordination com-
pounds or salts of other metals {RuCl2(PPh3)3, RuCl3,
Ni(acac)2 [1]}, lanthanide chloride crystal hydrates
make it possible to synthesize alkylquinolines in high
yield under mild conditions. The above series of metal
compounds is strongly limited, for other, more acces-
sible metal chloride crystal hydrates have not been
tested so far for catalytic activity in the synthesis of
quinolines. With the goal of optimizing methods for
the preparation of quinoline derivatives via search for
cheaper catalysts it was reasonable to test for catalytic
activity a broader series of crystal hydrates which were
not examined previously.
activity series of the examined crystal hydrates (yield,
%): Fe (94) > Al (89) > Co (55) > Mg (45) > Na (15).
The catalytic efficiency increases in parallel with the
known [3] complexing ability of metal ion toward
electron-donating ligands (coordination numbers of
Fe3+, Al3+, and Co2+ are equal to 6, 6, and 4, respec-
tively). The yield of 3-ethyl-2-propylquinoline in the
presence of sodium chloride (which does not form
complexes) was almost the same as in the reaction
performed in the absence of metal chloride. The best
yield was obtained using the cheapest crystal hydrate,
FeCl3·6H2O as catalyst, and its catalytic activity was
no less than that of TbCl3·6H2O which is known as the
most active catalyst in the above condensation. The
reaction starts even at 20°C (760 mm), is complete in
a short time (3–5 min), and is accompanied by heat
evolution (the mixture warms up to ~70°C). In 1 h
after the reaction completion, the originally homogene-
ous solution divided into two layers; the catalyst
resides in the bottom (heavier) phase, and it can be
readily separated as brownish solid. The catalyst can
be reused; the yield of 3-ethyl-2-propylquinoline in the
second cycle was 87%.
In the present work we studied the catalytic activity
of a series of the most accessible and least expensive
crystal hydrates (FeCl3 ·6H2O, AlCl3 ·6H2O, CoCl2·
6H2O, MgCl2·6H2O, and NaCl) in the condensation of
aniline with butyraldehyde in DMF (EtOH) at ~20°C,
which leads to the formation of 3-ethyl-2-propyl-
quinoline. The results showed the following catalytic
Thus we were the first to reveal high catalytic
activity of one of the most accessible and cheapest
crystal hydrate manufactured in Russia, FeCl3·6H2O,
in the condensation of aniline with butyraldehyde.
MCln ·6H2O
DMF, 3–5 min
NH2
Et
Pr
NHBu
CHO
+
+
Me
N
M = Fe(III), Al(III), Co(II), Mg(II); n = 2–3.
944

CATALYTIC ACTIVITY OF IRON(III), ALUMINUM(III), COBALT(II)
945
3-Ethyl-2-propylquinoline. The corresponding
metal chloride, FeCl3 ·6H2O, AlCl3 ·6 H2O, CoCl2·
6 H2O, MgCl2 ·6 H2O, or NaCl, 0.4 mmol, was dis-
solved in 7 ml of DMF (EtOH), and 1.8 ml (20 mmol)
of aniline and 3.96 ml (44 mmol) of butyraldehyde
were added in succession. After 5–10 min, the mixture
was extracted with diethyl ether (3×50 ml), the ex-
tracts were combined and dried over MgSO4, the sol-
vent was distilled off, and the residue was subjected to
fractional distillation under reduced pressure. The
solvent and tetramethylsilane as internal reference. The
elemental composition was determined on a Carlo
Erba Model 106 analyzer.
REFERENCES
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dine Bases), Moscow: Khimiya, 2003.
1
boiling point, H and 13C NMR spectra, and elemental
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Dzhemilev, U.M., Russ. J. Org. Chem., 2006, vol. 42,
p. 1573.
composition of the product were consistent with the
structure of 3-ethyl-2-propylquinoline and previously
reported data [2].
3. Cotton, F.A. and Wilkinson, G., Advanced Inorganic
Chemistry. A Comprehensive Text, New York: Wiley,
1966, 2nd ed.
1
The H and 13C NMR spectra were recorded on
a Jeol FX-90Q spectrometer using chloroform-d as
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 6 2009