Russian Journal of General Chemistry, Vol. 75, No. 4, 2005, pp. 658 659. Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005,
pp. 696 697.
Original Russian Text Copyright
2005 by Malysheva, Kuimov, Sukhov, Gusarova.
LETTERS
TO THE EDITOR
Reduction of Arylmethyl Chlorides
with a Phosphine Hydrogen Mixture in the KOH DMSO System
S. F. Malysheva, V. A. Kuimov, B. G. Sukhov, and N. K. Gusarova
Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Received September 15, 2004
Arylalkyl halides are reduced either under rigid
conditions or under the action of fairly expensive
reagents and complex systems.
hydrogen mixture. The reaction mixture was cooled
and extracted with benzene. The extract was washed
with water, dried with potassium carbonate, the sol-
vent was removed, and the residue was fractionated
in a vacuum to give 2.02 g (77%) of 1-methylnaphtha-
We used the example of benzyl chloride (Ia) and
1-chloromethylnaphthalene (Ib) to show for the first
time that arylalkyl chlorides can be reduced with
phosphine generated together with hydrogen from red
phosphorus in the KOH water organic solvent (di-
oxane, toluene) system [1]. The reaction is accom-
plished by bubbling the phosphine hydrogen mixture
through the arylmethyl chloride I KOH DMSO
system heated to 85 90 C. The yields of toluene IIa
and 1-methylnaphthalene II were 27 and 77%,
respectively.
1
lene, bp 94 C (5 mm Hg) (identified by the H and
13C NMR spectra). Found, %: C 92.49, H 7.51.
C11H10. Calculated, %: C 92.91: H 7.09. In the un-
distillable residue (0.13 g) by contained 31P NMR
using authentic samples [3], there were identified
bis(1-naphthylmethyl)phosphine oxide ( 36.8 ppm,
P
1JPH 470 Hz) and tris(1-naphthylmethyl)phosphine
oxide ( 42.4 ppm) (total yield ca. 1%). The aqueous
alkaline Player was acidified with HCl to pH 4 5 and
extracted with chloroform. The extracts were washed
with water, dried with calcium chloride, and the
solvent was distilled off to give 0.21 g of a product
that, according to the 31P NMR spectrum, contained a
7:1 mixture of organophosphorus compounds which
PH3 H2 KOH DMSO
ArCH2Cl
ArMe,
Ia, Ib
IIa, IIb
were assigned the structures of (1-naphthylmethyl)-
Ar = Ph (a),
(b).
1
phosphinic ( 33.4 ppm, JPH 557 Hz) and bis(1-
P
naphthylmethyl)phosphinic (
51.7 ppm) acids,
Expected phosphorylation products of benzyl chlo-
ride (benzyl- and dibenzylphosphines [2]) are formed
in the reaction studied in 6 and 32% yields, respec-
tively, while in the case of 1-chloromethylnaphthalene
the total yield of organophosphorus compounds is no
higher than 6%. In the PH3 DMSO system without
KOH, arylmethyl chlorides Ia and Ib are scarcely
reduced or phosphorylated. The mechanism of the
reaction is under study.
respectively (total yield 5%). P
The reaction of benzyl chloride with the PH3 H2
KOH DMSO system was carried out under the
analogous conditions. The reaction mixture was ex-
tracted with hexane, the extract was washed with
water, dried with potassium carbonate and analyzed
by GLC (reference decane) to identify toluene (27%).
The solvent was removed, and the residue was frac-
tionated in a vacuum to give 0.71 g of a product that,
according to the 31P NMR spectrum, contained a
Reaction of 1-chloromethylnaphthalene with the
PH3 H2 KOH DMSO system. To a suspension of
5 g of KOH 0.5H2O in 25 ml of DMSO and 3.4 ml
of water, purged with argon and saturated with the
phosphine hydrogen mixture, a solution of 3.26 g of
1-chloromethylnaphthalene in 5 ml of DMSO was
added dropwise over the course 2.5 h at 85 90 C with
stirring and continuous bubbling of the phosphine
1:4.2 mixture of benzylphosphine (t,
120.15 ppm,
P
1JPH 194 Hz) and dibenzylphosphine (d,
P
1
47.48 ppm, JPH 198.2 Hz) [2] (yields 6 and 32%,
respectively). The chloroform extract from the acidi-
fied aqueous alkaline solution contained no organo-
phosphorus compounds.
1
The H, 13C, and 31P NMR spectra were obtained
1070-3632/05/7504-0658 2005 Pleiades Publishing, Inc.
Malysheva
