1
548
GUSHCHIN et al.
Acetonitrile can take part in radical processes and
benzene, and toluene in the presence of t-BuNO 3 and
nitrone 4 to form phenyl radicals. In the reactions in
acetonitrile and toluene with spin traps 3 and 4, we
detected exclusively phenyl rather than cyanomethyl
and benzyl radicals which could be formed by the
radical substitution reactions with the solvents.
enter radical substitution reactions to form cyanometyl
radicals stabilized by the conjugation of the C≡N bond
with the p orbital of the methylene carbon atom, oc-
cupied of an unpaired electron [11]. In this connection
we suggested involvement of phenyl radicals in
reaction with СH CN [reaction (3)].
3
Nitroxyl radicals can also form in nonradical reac-
tions involving spin traps [13, 14]. We plan to explore
this possibility in our future work.
·
·
Ph + СH
3
C≡N ↔ PhH + СH
2
C≡N.
(3)
·
However, no formation of the known NCCH N(O )
2
Bu-t adduct (a 15.5, a 1 9.0 Oe) [11] was observed. It
N
H
EXPERIMENTAL
therefore was concluded that the main reaction route of
phenyl radical involves its addition to the nitrogen
atom in compound 3 rather than the radical substitution
in the solvent, even though the molar concentration of
the solvent is 300 times that of spin trap 3.
The ESR spectra were measure on a Bruker EMX
instrument (9.5 GHz) at the Center for Collective Use,
Razuvaev Institute of Organometallic Chemistry. A
two-arm molybdenum ampule with an additional outlet
for ESR was used. One arm was charged with spin trap
or 4 (0.1 mmol) and sealed. The other arm was
charged with organobismuth compound 1 or 2
0.1 mmol) and 1 mL of solvent. The ampule was
Since compound 3 can decompose under the action•
of light, one cannot exclude an alternative route of Ph
formation, specifically, by the radical substitution
3
·
(
reaction of t-Bu with organobismuth compound 1
degassed by three freeze-pump-thaw cycles and then
sealed. The reagents were thoroughly mixed before
analysis. Spectral measurements were performed
immediately after mixing and 20-min after irradiation
with scattered light. The spectra were processed using
Bruker BioSpin software (trial version).
[
reaction (4)].
·
·
t-Bu + PhBi(V) ↔ t-BuBi(V) + Ph .
To check this suggestion, we have studied the
radical decomposition of Ph Bi(O CEt) 1 in aceto-
nitrile in the presence of a light-resistant spin trap
С-phenyl-N-tert-butylnitrone PhCH=N(O)Bu-t 4. The
ESR spectrum showed a stable signal of the adduct
(4)
3
2
2
Triphenylbismuch dipropionate 1 [15, 16] and
triphenylbismuch dicrotonate 2 [17] were prepared by
oxidative coupling from triphenylbismuch, tert-butyl-
hydroperoxide, and propionic (crotonic) acid
(reagents molar ratio 1 : 1 : 2) at room temperature in
·
PhCH(Ph)N(O )Bu-t (a 14.7, a 2.7 Oe, g 2.0060).
N
H
The behaviour of Ph Bi(O CEt) 1 in the light in
3
2
2
the presence of spin trap 4 was studied in toluene
which, as known, is highly active in radical reactions.
In this case we observed no other products that adducts
of phenyl radical with nitrone 4 [PhCH(Ph)N(O )Bu-t,
a 14.4, a 2.2 Oe, g 2.0060]; the products of trapping
Et O. The reaction products were purified by
2
recrystallization from chloroform–petroleum ether
(1 : 4). The yields of purified products were 70%, mp
156°С (1), and 73%, mp 153°С (2).
·
N
H
more stable benzyl radicals, which could be formed in
the radical substitution reaction (5) involving toluene,
were not detected.
2
-Methyl-2-nitrosopropane 3 was prepared by the
oxidation of tert-butylamine with 20% aqueous
hydrogen peroxide in the presence of sodium tungstate
[18]. C-Phenyl-N-tert-butylnitrone 4 was synthesized
by the procedure in [19] from benzaldehyde, tert-
butylamine, and hydrogen peroxide.
·
·
Ph + PhCH
3
↔ PhH + PhCH
2
.
(5)
Bismuth(V) dicrotonate 2 showed the same
behavior in the light as propionate 1. The ESR
spectrum in benzene diplayed a signal of the adduct
REFERENCES
·
PhCH(Ph)N(O )Bu-t (a 14.4, a 2.2 Oe, g 2.0060);
N
H
1
2
3
. Xiao, P., Progr. Polym. Sci., 2015, vol. 41, p. 32. doi
0.1016/j.progpolymsci.2014.09.001
. Yagci, Y., Macromolecules, 2010, vol. 43, p. 6245. doi
0.1021/mal1007545
the parameters of this signal are in good agreement
with published data for an analogous adduct obtained
in benzene in the UV photolysis of triphenylbismuth
1
1
(
a 14.5, a 2.3 Oe) [12].
N
H
. Matano, Y., Shinokura, T., Yoshikava, O., and Imahori, H.,
Org. Lett., 2008, vol. 10, no. 11, p. 2167. doi 10.1021/
ol8005453
Thus, organobismuch compounds 1 and 2 decom-
pose on irradiation with scattered light in acetonitrile,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 7 2017
Gushchin
