Cyanoethylation of o-carboranes with acrylonitrile under conditions of phase-transfer catalysis

Article abstract of DOI:10.1023/A:1015495617969

o-Carboranes are cyanoethylated with acrylonitrile at the CH group of the o-carborane core in absolute benzene under conditions of phase-transfer catalysis.

Full text of DOI:10.1023/A:1015495617969

Russian Journal of General Chemistry, Vol. 72, No. 3, 2002, pp. 398 399. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 3, 2002,
pp. 427 428.
Original Russian Text Copyright
2002 by Zakharkin, Guseva, Balagurova.
Cyanoethylation of o-Carboranes with Acrylonitrile
under Conditions of Phase-Transfer Catalysis
L. I. Zakharkin, V. V. Guseva, and E. V. Balagurova
Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow, Russia
Received May 31, 2000
Abstract o-Carboranes are cyanoethylated with acrylonitrile at the CH group of the o-carborane core in
absolute benzene under conditions of phase-transfer catalysis.
It was briefly reported previously [1] that under
conditions of catalysis with 40% aqueous Triton B
o-carboranes are cyanoethylated at the CH group of
the o-carborane core to form 1-(cyanoethyl)-o-carbo-
ranes.
o-carborane V, and 1-vinyl-o-carborane VI.
RC CH + CH2=CH CN
B10H10
IV VI
KOH, C6H6
In this work we found that cyanoethylation of
o-carborane and its 1-substituted derivatives can occur
in absolute benzene under conditions of phase-transfer
catalysis at room temperature. As phase-transfer cata-
lyst we used finely divided KOH in combination with
dibenzo-18-crown-6. The reaction was performed at
an equimolar reactants ratio. Initially we took un-
substituted o-carborane I. The reaction occurred at
20 C by the following scheme:
RC CCH2CH2CN
dibenzo-18-crown-6,
20 C
B10H10
VII IX
+ (C3H3N)x(C2B10H11)y
R = C6H5 (IV, VII), CH3 (V, VIII), CH=CH2 (VI, IX).
In all cases, a polymeric tarry product formed,
from which compounds VII IX were separated by
dissolution in benzene. The yields of II, III, and VII
IX were 55 57% based on the o-carborane. The prod-
ucts were identified by the elemental analyses and
melting points.
HC CH + 2CH2=CH CN
B10H10
I
KOH, C6H6
HC CCH2CH2CN
dibenzo-18-crown-6,
The suggested procedure is a simple route to (1-cy-
20 C
B10H10
anoethyl)-o-carboranes.
II
+ CNCH2CH2C CCH2CH2CN
EXPERIMENTAL
B10H10
1-(Cyanoethyl)-o-carborane (II) and 1,2-bis-
(cyanoethyl)-o-carborane (III). A flask equipped
with a stirrer, a thermometer, and a CaCl2 tube was
charged with 6 g of o-carborane in 20 ml of absolute
benzene, 1 g of powdered KOH, and 0.15 g of di-
benzo-18-crown-6, and 5 g of freshly distilled acrylo-
nitrile was slowly added with stirring at 12 15 C. The
mixture was stirred for an additional 20 h at 20 C,
and a light orange product gradually precipitated.
According to TLC, no initial o-carborane remained in
the solution. Then 20 ml of water was added, the mix-
ture was stirred, and the precipitate was filtered off
and washed with water (2 5 ml) and benzene
(10 ml). The precipitate was dried on the filter at 50 C
in a water-jet-pump vacuum and recrystallized from
III
A specific feature of this reaction, in contrast to the
reaction catalyzed with Triton B, is formation of a
polymeric tarry by-product containing C, H, B, and N
atoms. This compound contains no free o-carborane,
which suggests its complex structure. Despite the fact
that the molar ratio of o-carborane and acrylonitrile
was 1 : 2, a mixture of II and III was obtained. Com-
pound III is formed along with II even at a 2 : 1 ratio
of carborane I and acrylonitrile. Compounds II and
III can be readily separated by crystallization.
Cyanoethylation under similar conditions was also
performed with 1-phenyl-o-carborane IV, 1-methyl-
1070-3632/02/7203-0398$27.00 2002 MAIK Nauka/Interperiodica

CYANOETHYLATION OF o-CARBORANES WITH ACRYLONITRILE
399
toluene. Compound III was obtained; yield 3.2 g
(31%), mp 225 226 C (cf. [1]). Found, %: C 38.63;
H 7.75; B 43.13; N 11.26. C8H18B10N2. Calculated, %:
C 38.40; H 7.20; B 43.20; N 11.20. The benzene layer
was separated from the aqueous phase and vacuum-
evaporated to dryness. The residue was recrystallized
two times from hexane with separation from the oily
layer by decanting. Compound II was obtained; yield
4 g (49%), mp 135 136 C (cf. [1]). Found, %: C
30.45; H 7.06; B 54.82; N 7.06. C5H15B10N. Calcu-
lated, %: C 30.41; H 7.69; B 54.79; N 7.10. Composi-
tion of the polymeric tar, %: C 49.30; H 6.09; B
21.51; N 11.75.
182 C. Yield of VII 3.7 g (71%). Found, %: C 48.46;
H 6.83; B 39.83; N 5.09. C11H19B10N. Calculated,
%: C 48.35; H 6.95; B 39.60; N 5.13.
1-Methyl-2-(cyanoethyl)-o-carborane (VIII). A
solution of 1.1 g of acrylonitrile in 2 ml of benzene
was added with stirring at 12 15 C to a mixture of
3.2 g of V, 0.4 g of KOH, 0.06 g of dibenzo-18-
crown-6, and 10 ml of benzene. The resulting mixture
was stirred for an additional 20 h. After common
workup, 2 g (46%) of VIII was obtained; mp 161
162 C (from toluene; cf. [1]).
1-Vinyl-2-(cyanoethyl)-o-carborane (IX). A solu-
tion of 1.3 g of acrylonitrile in 3 ml of benzene was
added at 10 12 C to a mixture of 4.2 g of VI, 0.5 g
of KOH, 0.06 g of dibenzo-18-crown-6, and 10 ml of
benzene. After common workup, 2.6 g (47%) of IX
was obtained; mp 128 129 C (from toluene). Found,
%: C 37.72; H 7.52; B 48.39; N 6.26. C7H17B10N.
Calculated, %: C 37.66; H 7.62; B 48.34; N 6.27.
1-Phenyl-2-(cyanoethyl)-o-carborane (VIII). A
solution of 0.75 g of acrylonitrile in 3 ml of dry
benzene was slowly added with stirring at 15 C to a
solution of 3 g of VII in 10 ml of absolute benzene,
0.4 g of finely divided KOH, and 0.05 g of dibenzo-
18-crown-6. Shortly thereafter, a light orange product
started to precipitate. The mixture was stirred for an
additional 20 h. After reaction completion, 10 ml of
water was added, and the precipitate was filtered off,
washed with absolute benzene (2 5 ml), and dried
in air; mp 181 182 C (cf. [1]). The benzene solution
was dried over CaCl2. The residue after distilling off
the solvent was recrystallized from toluene; mp 180
REFERENCES
1. Kalinin, V.N., Zurlova, O.M., and Zakharkin, L.I.,
J. Organomet. Chem., 1979, vol. 166, no. 3, pp. C37
C38.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 3 2002