UNUSUAL COURSE OF REACTION OF TRIPHENYL(2-p-TOLUYLETHYL)PHOSPHONIUM BROMIDE 1135
As seen from Scheme 1, keto phosphonium salt I
reacts with hydrazine along two pathways: -elimina-
tion with the formation of ketone II and elimination
of hydrogen to form ylide which exists in equilibrium
with its phosphorane form III. Compounds II and III
enter into the Wittig reaction yielding (C6H5)3P=O
reacts with compound II to form azino phosphorane
IV. The latter compound under the action of atmos-
pheric CO2 transforms along the Wittig reaction
pathway into an isocyanate derivative, which under
the reaction conditions closes the ring to form the
final compound V.
and a product containing no phosphorus, which we
failed to isolate. (C6H5)3P=O reacts with hydrazine
to form hydrazone (C6H5)3P=N NH2, which, in turn,
Under the action of water, a part of intermediately
forming isocyanate undergoes decarboxylation, and
the released carbon dioxide continues the reaction.
Scheme 2.
CO2
H2O
p-CH3C6H4 C CH=CH2
p-CH3C6H4 C CH=CH2
p-CH3C6H4 C CH=CH2
N NH COOH
N NH2
N N=C=O
I
The hypothesis that azino phosphorane IV enters
into Wittig reaction is supported by the results ob-
tained by Bestmann [4] in a study of the reaction with
benzaldehyde of the related compound (C6H5)3P=N
N=C(C6H5)2. It should be noted that performing this
reaction in a CO2 flow increased the yield of 6-tolyl-
2,3-dihydropyridazin-3-one to 34.1%.
The aqueous filtrate was extracted with chloroform,
the extract was poured into ether, and the white
crystals formed were filtered off and washed with
ether. 1.14 g (55%) of triphenyl(2-p-toluylethyl)-
phosphonium bromide hydrazone, mp 221 222 C,
was isolated. Found, %: C 66.5; H 5.60; N 5.54; P
6.19; Br 15.3. C28H28BrN2P. Calculated, %: C 66.8;
1
H 5.52; N 5.57; P 6.16; Br 15.9. H NMR spectrum
EXPERIMENTAL
(DMSO-d6 + CCl4), , ppm: 2.40 s (3H, CH3), 3.50 m
(2H, CH2), 4.00 m (2H, CH2), 7.20 8.00 m (15H,
1
3C6H5, p-C6H4). 31P NMR spectrum,
31.18 ppm.
The H NMR spectra were recorded on a Varian
Mercury-300 device with an operating frequency of
300 MHz, internal reference TMS.
P
b. Under CO2 flow. This experiment was carried
out similarly except that, after refluxing for 24 h,
CO2 was passed through the reaction mixture for 1.5
2 h. 0.26 g (34.1%) of 6-p-tolyl-2,3-dihydropyri-
dazin-3-one and 1.3 g (63%) of triphenyl(2-p-toluyl-
ethyl)phosphonium bromide hydrazone were ob-
tained. The melting points, elemental analyses, and
1H, 31P and 13C NMR spectra coincide with those of
the product obtained by procedure a.
Reaction of triphenyl(2-p-toluylethyl)phospho-
nium bromide with hydrazine hydrochloride.
a. Without CO2 flow. To a saturated solution of 2 g
of triphenyl(2-p-toluylethyl)phosphonium bromide in
methanol, we added 3.37 g of hydrazine hydrochloride
dissolved in a minimal amount of water. The reaction
mixture was refluxed on a water bath for 30 h. The
precipitate formed was filtered off, washed with
water, and dried in a vacuum. 0.14 g (18%) of 6-p-
tolyl-2,3-dihydropyridazin-3-one was obtained, mp
240 241 C. Found, %: C 70.5; H 5.51; N 15.1.
C11H10N2O. Calculated, %: C 70.97; H 5.37; N 15.05.
1H NMR spectrum (DMSO-d6 + CCl4), , ppm: 2.38 s
(3H, CH3), 6.86 d (1H, C4N2H2, J 9.9), 7.20 d (2H,
C6H5, J 8.1), 7.68 d (2H, C6H5, J 8.1), 7.80 d (1H,
C4N2H2, J 9.9), 12.97 br.s (1H, NH). 13C NMR spec-
trum, C, ppm: 20.66 (CH3); 125.14 (C2 and C6 );
REFERENCES
1. Khachikyan, R.Dzh., Karamyan, N.V. and Indzhi-
kyan, M.G., Zh. Obshch. Khim., 2005, vol. 75, no. 12,
p. 1984.
2. Khachatryan, R.A., Khachikyan, R.Dzh., Kara-
myan, N.V., Panosyan, G.A., and Indzhikyan, M.G.,
Khim. Geterotsikl. Soedin., 2004, no. 4, p. 54.
3. Khachikyan, R.Dzh., Karamyan, N.V., Panosyan, G.A.,
and Indzhikyan, M.G., Izv. Ross. Akad. Nauk, Ser.
Khim., 2005, no. 8. p. 1923.
128.83 (C3 and C5 ); 129.60 (C1 ); 130.33 (C4 );
131.90 (C4); 137.87 (C5); 143.23 (C6); 159.76 (C=O).
Mass spectrum (EI, 70 eV), m/z (Irel, %): 186 [M]+.
4. Bestmann, H.J., Angew. Chem., 1960, vol. 72, no. 9,
p. 326.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 6 2007
Khachikyan
