ISSN 1070-3632, Russian Journal of General Chemistry, 2006, Vol. 76, No. 10, pp. 1562 1563.
Original Russian Text V.I. Rakhlin, T.F. Podgorbunskaya, R.G. Mirskov, M.G. Voronkov, D.V. Gendin, 2006, published in Zhurnal Obshchei Khimii,
2006, Vol. 76, No. 10, pp. 1629 1630.
Pleiades Publishing, Inc., 2006.
Reactions of N-Bromohexamethyldisilazane
with Triorganylsilanes
V. I. Rakhlina, T. F. Podgorbunskayab, R. G. Mirskova,
M. G. Voronkova, and D. V. Gendinb
a Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: vir@irioch.irk.ru
b Irkutsk State Technical University, Irkutsk, Russia
Received August 3, 2006
Abstract Reactions of N-bromohexamethyldisilazane (Me3Si)2NBr with Si H compounds of the general
formula RR2SiH yield up to 90% of unsymmetrical disilazanes (Me3Si)2NSiRR and bromotrimethyl-
2
silane. An unexpected solvent effect on the reaction conditions is revealed: In benzene the products are
formed already on mixing, whereas in cyclohexane, under UV irradiation only.
DOI: 10.1134/S1070363206100094
N-Bromohexamethyldisilazane (Me3Si)2NBr is a
promising reagent for free-radical bromination of
organic and organoelement compounds. With
(Me3Si)2NBr, unlike what is observed with most
brominating agents, abstraction of hydrogen from
substrates involves the nitrogen-centered hexamethyl-
disilazanyl radical, rather than the bromine radical,
which alters the selectivity of the whole process [1].
synthesis. We recently developed a procedure for the
preparative synthesis of (Me3Si)2NBr in up to 80%
yield, based on photoinduced reaction of N-bromo-
succinimide with hexamethyldisilazane in carbon
tetrachloride [2]. To reveal the synthetic potential of
(Me3Si)2NBr, we studied its reactions with triorganyl-
silanes, tetramethyldisiloxane, and tetramethyldisila-
zane under UV irradiation. The reactions unex-
pectedly gave unsymmetrical hexaorganyldisilazanes
I VI in yields of up to 83% and bromotrimethylsilane
in quantitative yield.
The reactivity of (Me3Si)2NBr was poorly studied
so far because of the lack of reliable methods of its
h
(Me3Si)2NBr + RR2SiH
Me3SiNHSiRR2 + Me3SiBr,
RR2 = MePh2 (I); Me2Ph (II); Ph3 (III); (EtO)3 (IV); HMe2SiOSiMe2 (V); HMe2SiNHSiMe2 (VI).
The reactions were performed under UV irradiation
of the reagent mixture without solvent in a prelimi-
narily evacuated glass ampule or by stirring a solution
of both the components in benzene or cyclohexane.
The reaction in benzene proceeds without irradiation,
it starts with heat evolution and is complete within
15 30 min. The reaction in cyclohexane occurs under
UV irradiation only. The simplicity and sufficiently
high yields of the final products allows this procedure
to be recommended for the preparative synthesis of
unsymmetrical disilazanes.
thoroughly dried ampoule. The mixture was degassed
by the freezing thowing procedure and then irradiated
for 10 h with UV light (DRG-400 lamp). The reaction
products were isolated by vacuum distillation and
identified by 1H NMR spectroscopy at 400 MHz
(Bruker spectrometer DPX-400).
1,1,1,3-Tetramethyl-3,3-diphenyldisilazane (I),
1
bp 163 C (9 mm Hg), n2D0 1.5435, yield 83%. H
NMR spectrum (CDCl3, TMS), , ppm: 0.02 s (9H,
SiMe3), 0.61 s (3H, SiMe), 7.64 7.19 m (10H, SiPh2).
1,1,1,3,3-Pentamethyl-3-phenyldisilazane (II),
bp 87 C (2 mm Hg), nD20 1.4861, yield 46.6%.
1HNMR spectrum (CDCl3, TMS), , ppm: 0.15 s (9H,
SiMe3), 0.45 s (6H, SiMe2), 7.47 7.45 m (5H, SiPh).
EXPERIMENTAL
General procedure. Equimolar mixture of tri-
organylsilane and (Me3Si)2NBr was placed in a
1562
Rakhlin
