SHAGUN et al.
1550
Scheme 3.
[ICH2CO]+
+
m/z 141 (45)
+ m/z 127 (29)
·
O
[ICH2COCH2]
I
I
·
I
+
·
m/z 183 (100)
+ m/z 169 (29)
CO
+ m/z 155 (6)
ICH2
[M]+, m/z 310 (Irel 17%)
1,3-diiodoacetone (II) was proved by independent
synthesis according to the procedure described in [9]
(Scheme 2). The IR, 1H and 13C NMR, and mass spec-
tra, analytical data, and melting points of samples of II
obtained by photochemical transformation of iodoace-
tone and by halogen exchange in 1,3-dichloroacetone
were identical.
IR spectrum, ν, cm–1: 2981, 2930, 1723, 1648, 1368,
1248, 1193, 1011, 845, 682, 575, 516, 414 (cf. [9]).
The IR spectra were recorded in KBr on a Bruker
1
13
IFS-25 instrument. The H and C NMR spectra were
measured on a Bruker DPX-400 spectrometer at 400
and 100 MHz, respectively. The mass spectra were
obtained on a GCMS-QP5050A instrument (electron
impact, 70 eV; quadrupole mass analyzer; direct
sample admission into the ion source). Photolysis of
iodoacetone I was performed in a quartz flask under
irradiation with a DRT-230 mercury lamp (λ 254 nm).
The purity of the products was checked by TLC on
Silufol UV-254 plates using chloroform as eluent.
Ionization of diiodoacetone II under electron
impact gives its molecular ion [M]+ with m/z 310
(Scheme 3). Its subsequent fragmentation involves
mainly cleavage of the C–I bond to produce [M – I]+
ion with m/z 183 as the most abundant, indicating very
easy elimination of iodine from the molecular ion. The
presence in the mass spectrum of a strong odd-electron
[CH2I2]+· ion peak, m/z 268 (22) is likely to result from
migration of the halogen atom and elimination of
ketene molecule (Scheme 4).
This study was performed under financial support
by the President of the Russian Federation (program
for support of leading scientific schools, project
no. NSh-255.2008.3).
Scheme 4.
REFERENCES
+
·
I
1. Puronit, P.C. and Sonawane, H.R., Tetrahedron, 1981,
O
vol. 37, p. 873.
[CH2I2] +
·
–CH2CO
2. Shun-Jun Ji and Horiuchi C.A., Bull. Chem. Soc. Jpn.,
2000, vol. 73, p. 1645.
3. Izava, Y., Tomioka, H., Natsume, M., Beppu, S., and
I
[M]+, m/z 310 (17)
m/z 268 (11)
Tsujii, H., J. Org. Chem., 1980, vol. 45, p. 4835.
4. Izava, Y., Ishiguro, K., and Tomioka, H., Bull. Chem. Soc.
Jpn., 1983, vol. 56, p. 1490.
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let, J.E., Can. J. Chem., 1973, vol. 51, p. 1435.
6. Rykov, S.V., Nikiforova, G.A., and Skakovskii, E.D., Izv.
Akad. Nauk SSSR, Ser. Khim., 1987, p. 2601.
Thus we have described novel photochemical dis-
proportionation of iodoacetone, which may be re-
garded as a simple and convenient method for the
synthesis of 1,3-diiodoacetone.
1,3-Diiodopropan-2-one (II). A solution of 1.2 g
(6.5 mmol) of iodoacetone in 10 ml of carbon tetra-
chloride was saturated with argon and irradiated with
UV light at room temperature over a period of 7 h
(until the main products no longer accumulated in the
mixture). The mixture was cooled to –20°C, and the
precipitate was filtered off and dried under reduced
pressure. Yield 0.45 g (45%), colorless crystals, mp 61–
62°C (from ethanol); published data [9]: mp 62–63°C.
7. Pfordte, K. and Leuschner, G., Justus Liebigs Ann. Chem.,
1961, vol. 646, p. 23.
8. Barltrop, J.A. and Coyle, J.D., Excited States in Organic
Chemistry, London: Wiley, 1975. Translated under the
title Vozbuzhdennye sostoyaniya v organicheskoi khimii,
Moscow: Mir, 1978, p. 223.
9. Crowder, G.A. and Smyrl, N., J. Mol. Struct., 1971,
vol. 7, p. 478.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 10 2008