A.R. Kurbangalieva et al. / Journal of Molecular Structure 595 52001) 15±20
17
2.3. Syntheses
was acidi®ed with a dilute solution of hydrochloric
acid to pH 1±2. We have thus obtained a bright-
red powdered sediment of compound 1I), m.p. 94±
968C 1m.p. 968C [22]). Yield 56%. Found, %: C
56.53; H 4.73. Calculated for C17H14N2OSe, %: C
59.82; H 4.11.
With the recrystallisation of 1-phenyl-3-methyl-4-
benzoylpyrazol-2-in-5-selenone 1I) from ethanol
di11-phenyl-3-methyl-4-benzoylselenopyrazolyl-
5)diselenide 1II) is isolated as a red crystal,
m.p. 139±1408C 1m.p. 1418C [22]).
1-Phenyl-3-methyl-4-benzoyl-5-chloropyrazole
was synthesised accordingto the method described in
Ref. [21], followed by recrystallisation from ethanol.
M.p. 88±908C 1m.p. 888C), thin-layer chromato-
graphy, Rf 0.55. IR 1Nujol): n 1cm21) 1625
1
1Cy6;O); 1583, 1520 1Cy6;C and Cy6;N). H NMR
1CDCl3): d 1ppm) 2.36 1s, 3H, CH3), 7.40±7.85 1m,
10H, C6H5).
1-Phenyl-3-methyl-4-benzoylpyrazol-2-in-5-sele-
none 1I) was synthesised accordingto modi®ed
method outlined in Ref. [22].
3. Results and discussion
In a round-bottom ¯ask supplied with return refrig-
erator an alcohol solution of 4.35 g10.015 mol) of 1-
Selenopyrazolone 1I) was obtained by followinga
modi®ed method [22] described in Section 2 by the
reaction of potassium hydroselenide and 1-phenyl-3-
methyl-4-benzoyl-5-chloropyrazole in an alcohol
solution:
phenyl-3-methyl-4-benzoyl-5-chloropyrazole
with
the saturated alcohol solution of 3.5 g10.03 mol) of
potassium hydroselenide was heated for an hour. In
the reaction, we used a double excess of KSeH in
comparison with the stoichiometric quantity. Potas-
sium hydroselenide, used as the selenation reagent,
was obtained in situ by saturatingbubblingof
hydrogen selenide with a 20% alcohol solution of
potassium hydrate. Hydrogen selenide was obtained
by heatingthoroughly mixed selenium, paraf®n and
asbestos in a round ¯ask.
Reaction mixture was left over the night, ®ltered
with precipitated potassium chloride and a transparent
red ®ltrate was evacuated on a water-jet pump
1without heatingand in an inert atmosphere). Residue
obtained after topping1evaporation) of ethanol was
treated with water, the main part of the product
beingdissolved in water 1it is a turbid solution A);
and the insoluble part solidi®ed as a bright-yellow oil
1product B). Product B was dried and dissolved in
ethanol. While coolingthe ethanol solution a yellow
crystalline sediment fell out, m.p. 214±2168C,
assigned to bis11-phenyl-3-methyl-4-benzoylpyra-
zolyl-5)selenide 1III). Found, %: C 67.95; H 5.11.
Calculated for C34H26N4SeO2, %: C 67.89; H 4.36.
Solution A was ®ltered out from the impurities of
solid yellow sediment. Yellow transparent ®ltrate
1pH 13) was acidi®ed with a dilute solution of
hydrochloric 1muriatic) acid until the red sediment
fell out. This sediment was then ®ltered, washed in
water and dried. The product was puri®ed twice by
reprecipitation: red sediment was dissolved in an
alkaline solution and slowly with intense mixing
Compound 1I) isolated from the reaction mixture was
abright-redpowderedsediment, whichwasfurtherpuri-
®ed by the reprecipitation of alkaline solutions with
dilute hydrochloric acid. In IR spectra of compound
1I) in Nujol there are narrow intense absorption bands
at 1648 and 1628 cm21, assigned to the carbonyl group
of the benzoyl substituent; bands in the range of 1600
and 1502 cm21 are characteristic of phenyl groups; at
1580and1550 cm21 Ð signalsofthepyrazolering;and
additionally a broad weak absorption band of the SeH-
g roup in the rang e of 2450 2cm1. The bands of
stretchingvibrations of NH-rgoup in the raneg of
,2550 cm21, characteristic of the NH tautomeric
forms of the known pyrazolones and thiopyrazolones,
were absent in IR spectra.
The set of obtained spectral characteristics allowed
us to assign the structure of SeH-tautomeric form to
the obtained compound apparently stabilised by weak
intramolecular hydrogen bond with the carbonyl
group of benzoyl substituents, as evident from the