NEW PHOTOCHEMICAL TRANSFORMATIONS OF 1-IODOPROPAN-2-ONE
251
=
CHI fragment, at 76.78 ppm. The chemical shifts of
lattice) relaxation since the concentration of para-
magnetic centers in the samples studied was less than
10 spin/g. Rough estimation using the three-pulse
echo modulation technique has shown that the
dependence of the decay of the echo amplitude on the
T value includes contributions from some other re-
the HC= and =C< fragments are registered at 123.76–
20
1
37.70 and 148.64–154.24 ppm, respectively.
In the IR spectra of the soluble fraction А the
–
1
absorption bands at 1563 and 1636 cm correspond to
the C=C bond stretching vibrations in polyconjugated
–
1
laxation mechanisms and the Т
1
–Т model does not
1
2
compounds. An intense band at 458 cm suggests the
presence of an unsaturated =C–I bond. The absorption
allow to reliably estimate time Т . This suggests, in
–
1
particular, the absence of ordering in the oligomer
structure and requires the use of more complex
techniques.
bands at 2962, 2922, 2852 and 3124 cm are
characteristic of the C–H vibrations in the СН and
3
СН=С fragments [4]. All this corresponds to the
presence of structural fragments IV–VI in fraction А.
Photochemical polycondensation of 1-iodo-2-
propan-2-one. 4 g of 1-iodopropan-2-one (I) was
irradiated with UV light (λ = 254 nm) in an argon
atmosphere while stirring at 80–90°С for 6–7 h until
the temperature raised to 122°С and the reaction
mixture became viscous (the reaction was monitored
by NMR and TLC). From the obtained viscous mass
Investigation of electroconductivity of fractions А
and B close in composition has shown that they are
high-ohmic organic semiconductors having electrocon-
ductivity of 10 Sm/cm. Solutions of fraction А in chloro-
form, acetone, acetonitrile form films with high adhesion
to various substrates (quartz, glass, aluminum, etc.).
–9
(
20 ml) the soluble part was extracted with acetone.
Both fractions, as could be suggested from their
deep, almost black color, are paramagnetic and show
in the continuous wave ESR spectra similar intense
Addition of 60 ml of hexane to the acetone solution
resulted in formation of a precipitate which was
thoroughly washed with ether to constant weight and
dried in a vacuum. Yield 0.3 g (71%), black powder,
1
9
(
concentration of paramagnetic centers ca. 10 spin/g)
narrow singlet signals with the following parameters
fraction А: g = 2.0056, ∆Н = 10.6 gauss, A/B = 0.84;
T
= 187–190°С. Found, %: С 41.03; Н 3.84; I
decomp.
(
4
5
9.36. С Н I . Calculated, %: C 42.51; Н 7.48; I
1
44 304 16
fraction B: g = 2.0054, ∆Н = 9.1 gauss, A/B = 0.86),
corresponding to polymers with extended conjugation
system, which is also in agreement with the presence
of groups IV–VI in the polymer. The signals of both
fractions are equally asymmetric (asymmetry para-
meter A/B < 1), the upper part of the signal (more
wide) being described by the Lorentz line and the
lower part (more narrow), by the Gauss line, which is
indicative of anisotropy of the g-factor. Substantial
deviation of the g-factor from the free electron value is
due to interaction of the free electron with heavy
iodine atom.
0.00. Insoluble in acetone fraction was thoroughly
washed with methanol, chloroform, ether to constant
weight. Yield 0.6 g, glittering black powder, T
3
>
decomp.
60°С. Found, %: С 42.31; Н 3.28; I 47.73.
IR spectra of solid samples were recorded on a
Spectrum HE-3100 Varian spectrometer with the
attenuated total reflection unit (ATR) on a SeZn glass,
1
and on a FT-IR Vertex 70 Ram II spectrometer. Н
1
3
(
400 MHz) and С (100 MHz) NMR spectra were
registered on a Bruker DPX 400 instrument in CDCl .
3
ESR spectra of solid samples were taken on a
Bruker ELEXSYS E580 spectrometer at room
temperature in continuous-wave and pulse regimes (for
primary echo π/2 = 32 ns, for the echo modulation
π/2 = 16 ns). Relaxation times were estimated from the
Т –Т model [5]. The molecular mass was determined
Using the two-pulse (π/2–τ–π) and three-pulse
(
π/2–τ–π/2–T–π/2) echo modulation technique at room
temperature we have obtained the echo-detected ESR
signals. In the former case, for fraction B, the ex-
ponential decay of the echo amplitude in semi-
1
2
on a Waters gel chromatograph with flow refracto-
meter detector at 25°С, eluent THF. Specific electric
conductivity measurements were performed using a
VK2-16 electrometric amplifier. Photolysis of 1-iodo-
propan-2-one was performed in a quartz flask by
irradiation with mercury lamp DRT-230 (λ = 254 nm).
The purity of the isolated products was monitored by
TLC on Silufol UV-254 plates with chloroform as
eluent.
logarithmic coordinates gives linear dependence on τ
2
(
R = 0.999; n = 14), that allowed to determine the
transverse (spin-spin) relaxation time Т equal to
2
5
56 ns with high precision. For fraction A the similar
dependence was obtained with correlation coefficient
0
.990 and the calculated value of Т is 625 ns.
2
The spectral diffusion was assumed to give no
contribution to the value of the longitudinal (spin-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 2 2010
Voronkov
