THALLIUM(III) OXIDE AS AN OXIDATIVE REAGENT
453
Potassium bromide of “chemically pure” grade was
used without additional purification. Arenes of
“chemically pure” grade were distilled. Trifluoroacetic
acid of “pure” grade was dried over P2O5 and then
distilled. Physicochemical constants of arenes and
trifluoroacetic acid were consistent with the reported
data [5–7]. Aluminum oxide of the chromatographic
grade and the Brockman activity III was used.
2-Bromo-4-nitrotoluene. A mixture of 0.686 g of
p-nitrotoluene, 1.19 g of KBr, 4.567 g of Tl2O3, and
15 ml of trifluoroacetic acid was stirred for 165 h at
room temperature, diluted with 50 ml of water and
4 times extracted with chloroform. The extract was
twice washed with water and dried over sodium
sulfate. Chloroform was slowly distilled off, and the
sample was kept in a vacuum to give 1.07 g of the
residue. It was subjected to TLC on Al2O3, elution
with 1:2 chloroform–petroleum ether (bp 40–68°C),
development with the iodine vapor. By means of
reference substances it was shown that the residue
contained 2-bromo-4-nitrotoluene (Rf 0.79). The
sample was crystallized from ethanol to give the
product with mp 74°C, reported data [6] mp 75°C.
Found, %: C 38.86, H 2.84. C7H6BrNO2. Calculated,
%: C 38.92, H 2.80.
4-Bromo-tert-butylbenzene. A mixture of 1.342 g
of tert-butylbenzene, 0.595 g of KBr, 2.284 g of Tl2O3,
and 10 ml of trifluoroacetic acid was stirred for 25 h at
room temperature. After that the reaction mixture was
treated with 34 ml of water and four times extracted
with chloroform. The extract was twice washed with
water, dried over sodium sulfate and subjected to TLC
on aluminum oxide, elution with petroleum ether (40–
68°C), development with iodine vapor. It was found
that the extract contained 4-bromo-tert-butylbenzene
(Rf 0.81). Petroleum ether was distilled off, and the
residue was kept in a vacuum to give the oily product.
It was treated with hexane, and 4-bromo-tert-
butylbenzene was separated from the other substances
by column chromatography on aluminum oxide,
elution with hexane. The eluate was evaporated to give
0.92 g (86%) of 4-bromo-tert-butylbenzene, nD20
1.5412, bp 231–232°C, reported data [6] bp 232°C.
Finally the light beige precipitate was formed. The
reaction mixture was stirred for 2 h, 0.95 ml of
trifluoroacetic acid was added, and stirring was
continued for additional 0.5 h. The precipitate was
filtered off, yield 3.2 g. It was several times washed
with water and dried to give 0.50 g of diphenylthallium
trifluoroacetate, yield 30% with respect to phenyl-
hydrazine. The product obtained was crystallized from
ethyl acetate, mp 274–276°C. IR spectrum, ν, cm–1:
3062, 1624, 1570, 1480, 1435, 1196, 1150, 1140, 702.
Found, %: C 35.56, H 2.24, Tl 43.10. C14H10F3O2Tl.
Calculated, %: C 35.66, H 2.14, Tl 43.34.
Thallium(I) trifluoroacetate, 2.5 g, mp 109–110°C,
was isolated from aqueous filtrate. Benzene filtrate
was subjected to TLC on Al2O3, elution with 1.5:1
hexane-chloroform, development with I2. Using the
authentic substance we have found that filtrate
contains biphenyl (Rf 0.87). Benzene was distilled off,
biphenyl was isolated and purified by column
chromatography on Al2O3, elution with hexane, yield
0.017 g, mp 70°C, reported data [6] mp 71°C.
Diphenylthallium acetate was obtained analo-
gously. Yield 32%, mp 258–263°C , reported data [9]
mp 267–262°C. IR spectrum, ν, cm–1: 3059, 2935,
2862, 1635, 1580, 1551, 1484, 1458, 1437, 1380,
1161, 1140, 1201. Found, %: C 40.18, H 3.21, Tl
48.76. C14H13O2Tl. Calculated, %: C 40.26, H 3.14, Tl
48.94.
Diphenylthallium tetrafluoroborate was obtained
as described above. Yield 30.5%, mp 305–307°C.
Reported data [9] mp 306–308°C. IR spectrum, ν, cm–1:
3050, 2964, 2925, 1581, 1479, 1433, 1035, 765, 725,
686.
Diphenylthallium bromide was obtained as
described above. It was isolated from precipitate by
extraction with DMF. Yield 30.8%, mp 295°C. Found,
%: C 32.74, H 2.34, Tl 46.80. C12H10BrTl. Calculated,
%: C 32.87; H 2.30, Tl 46.61.
4-Nitrodiphenyl. To a suspension of 2.350 g of
Tl2O3 in 35 ml of benzene 0.78 ml of trifluoroacetic
acid was added, and an argon flow was bubbled
through the reaction mixture. After that it was heated
to 50°C and 0.788 g of 4-nitrophenylhydrazine in
150 ml of benzene heated to 50°C was gradually
added. The mixture obtained was stirred for 2 h at
50°C and then heated to boiling. The solvent was
distilled off, and an oily cherry-colored residue was
obtained. It was examined by TLC on Al2O3, elution
with 3:1 petroleum ether (40–68°C)–chloroform. 4-Nitro-
Diphenylthallium trifluoroacetate. To a suspension
of 2.538 g of Tl2O3 in 30 ml of benzene stirred with a
magnetic stirrer a solution of 0.768 g of phenyl-
hydrazine in 5 ml of benzene was added dropwise at
room temperature in the course of 30 min under argon.
Liberation of nitrogen was observed immediately, and
the dark brown suspension gradually became lighter.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 3 2010