ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 2, pp. 338–339. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © A.I. Rakhimov, S.A. Avdeev, Le Thi Doan Chang, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79, No. 2, pp. 348–349.
LETTERS
TO THE EDITOR
Specific Features of the Reaction of m-Phenoxybenzyl Chloride
with Sodium Thiobarbiturate
A. I. Rakhimova,b, S. A. Avdeevb, and Le Thi Doan Changa
a Volgograd State Technical University ,
pr. Lenina 28, Volgograd, 400131 Russia
e-mail: organic@vstu.ru
b Institute of Chemical Problems of Ecology, Russian Academy of Natural Sciences, Volgograd, Russia
Received September 1, 2008
DOI: 10.1134/S1070363209020339
Recently [1, 2] by kinetic experiments was estab-
lished that introduction of phenoxy substituent to meta
position of benzyl chloride decreases its reactivity with
sodium salt of 6-methyl-2-thiouracyl 5.8 times.
reactivity of halide after introduction of the phenoxy
substituent to meta position of benzyl chloride.
2-[(3-Phenoxybenzyl)thio]pyrimidin-4,6-(1H,5H)-
dione (III). To a suspension of 4.4 g of thiobarbituric
acid in 60 ml of water–dioxane mixture (45 ml of di-
oxane and 15 ml of water) a solution of 1.3 g of sodium
hydroxide in 30 ml of water was added dropwise with
stirring. The mixture obtained was kept for 1 h until
the complete homogenization. After that a solution of
7.3 g of compound I in 5 ml of dioxane was added
dropwise. Resulting mixture was stirred for 1 h and left
overnight. On the next day the solvent was evaporated
in a vacuum, and the precipitate formed was filtered
off and crystallized from absolute ethanol. Yield 5.3 g
In the report presented it is shown that the reaction
of m-phenoxybenzyl chloride I with sodium thiobar-
biturate II proceeds with the lower (50%) conversion
(as compared to benzyl chloride IV) of the reagent II
to form 2-[(3-phenoxybenzyl)thio] pyrimidin-4,6(1H,5H)-
dione III.
O
O
H
H
I, IV
N
N
Na
S
N
O
S
N
O
1
(54%), mp 192°C (with decomposition). H NMR
spectrum, δ, ppm: 4.72 s (2H, CH2–C=O), 5.18 s (2H,
CH2–C6H4), 6.67–7.41 m (9H, Harom), 11.8 s (1H, NH).
Found, %: N 7.54. C17H14N2O3S. Calculated, %: N 8.58.
R
R = H (V), R = OC6H5 (III).
2-(Benzylthio)pyrimidin-4,6(1H,5H)-dione (V) was
obtained analogously. Yield 70%, mp 230°C (with
decomposition). 1H NMR spectrum, δ, ppm: 4.78 s (2H,
CH2–C=O), 5.15 s (2H, CH2–C6H5), 6.93–7.11 m (5H,
The yield of S-benzylation product is 70% for com-
pound V and 54% for compound III.
Quantum chemical analysis (AM1 method [3, 4]) of
ions generated from thiobarbituric acid under the
action of sodium hydroxide shows a high stability of
the carbanion (E = –1351.4 kcal mol–1) and the thiolate
anion (E = –1345.5 kcal mol–1). Direction of the
reaction with the participation of the thiolate anion is
determined evidently by steric availability of the
reaction center. It is also proved by the decrease in
Harom), 11.8 s (1H, NH). Found, %: N 11.63. C11H10·
N2O2S. Calculated, %: N 11.96.
1H NMR spectra were registered on a Varian Mercury
300 (300 MHz) spectrometer in DMSO-d6 against
internal HMDS. Melting points were measured
according to [5].
338
Rakhimov
