Diazotization of 6-amino-2-phenyl-7-chloro-2H-benzotriazole-4-carboxylic acid and transformations of the resulting diazo compounds

Article abstract of DOI:10.1007/s11176-005-0097-1

6-Amino-2-phenyl-7-chloro-2H-benzotriazole-4-carboxylic acid was prepared by oxidation of 2,5-diamino-4-chloro-2-phenylazobenzoic acid, and its diazotization and subsequent transformations of the diazo compounds were studied. 7-Hydroxy-2-phenyl-2H-benzotr

Full text of DOI:10.1007/s11176-005-0097-1

Russian Journal of General Chemistry, Vol. 74, No. 11, 2004, pp. 1763 1765. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004,
pp. 1894 1897.
Original Russian Text Copyright
2004 by Artamonov, Perevalov.
Diazotization of 6-Amino-2-phenyl-7-chloro-2H-benzotriazole-
4-carboxylic Acid and Transformations
of the Resulting Diazo Compounds
G. L. Artamonov and V. P. Perevalov
Mendeleev Russian University of Chemical Engineering, Moscow, Russia
Received January 31, 2003
Abstract 6-Amino-2-phenyl-7-chloro-2H-benzotriazole-4-carboxylic acid was prepared by oxidation of
2,5-diamino-4-chloro-2-phenylazobenzoic acid, and its diazotization and subsequent transformations of the
diazo compounds were studied. 7-Hydroxy-2-phenyl-2H-benzotriazole-4-carboxylic acid was prepared.
The chemical properties of 2H-benzotriazoles con-
taining several substituents in the benzene moiety are
studied insufficiently [1, 2] because of limited avail-
ability of di- and trisubstituted m-phenylenediamines
required for their preparation. In this connection, start-
ing from 4-chloro-3,5-diaminobenzoic acid, we pre-
pared by the known scheme [3] 6-amino-2-phenyl-7-
chloro-2H-benzotriazole-4-carboxylic acid I and per-
formed with it certain chemical transformations.
in the form of quinone diazide VI. This compound
was also prepared by treatment of a solution of diazo-
nium salt II in acetic acid with sodium carbonate. The
presence in VI of the diazo function in the form of
diazo rather than diazonium group is confirmed by a
1
strong narrow band in the IR spectrum at 2180 cm
[5 7]. Formation of VI is apparently due to lability of
the chlorine atom in the molecule of II; this atom is
replaced by the hydroxy group under the action of
water, which is followed by the tautomeric transfor-
mation into the diazonium salt of hydroxybenzotria-
zole. Diazo compound VI is highly stable, so that we
detected a molecular ion in its mass spectrum.
Amino compound I is diazotized in HCl difficultly
because of its poor solubility and low basicity of the
amino group caused by the electron-withdrawing
properties of the triazole moiety [4]. After prolonged
standing at room temperature, the reaction mixture
contains, according to TLC, the starting compound
exhibiting strong blue luminescence. When the diazo-
tization was performed with addition of acetic acid,
in which compound I is readily soluble, the reaction
was complete in 1 h. The resulting diazonium salt II
entered into further transformations without compli-
cations only in acid solution: Its reaction with N,N-di-
ethylaniline yielded azo compound III, and the reac-
tion with a solution of SO2 in acetic acid in the pres-
ence of HCl yielded benzotriazolesulfonyl chloride IV
and 6,7-dichloro-2-phenyl-2H-benzotriazole-4-carbox-
ylic acid V. At the same time, attempted azo coupling
of diazonium salt II with 2-naphthol in alkaline solu-
tion failed because of tarring of the reaction mixture,
probably caused by instability of II under these con-
ditions.
Quinone diazide VI is formed in a high yield and is
stable in storage. It reacts with 2-naphthol in alkaline
solution to form 2,2-diaryl hydroxy azo compound
VII and undergoes nitrogen substitution in a strongly
acidic or strongly alkaline solution, i.e., under the
conditions facilitating the transformation of the qui-
none diazide into the diazo compound salt [8].
Prolonged heating of VI in ethanol in the presence
of copper(II) sulfate resulted in substitution of the di-
azo group with hydrogen and formation of 7-hydroxy-
2-phenyl-2H-benzotriazole-4-carboxylic acid VIII.
In refluxing ethanolic solution of NaOH, compound
VIII is formed from VI considerably faster.
EXPERIMENTAL
We believe that the specific features of the diazo
compound obtained from I are confirmed by the re-
sults of diazotization in aqueous sulfuric acid at ele-
vated temperature. The diazo compound isolated from
the reaction was characterized by H NMR, mass, and
IR spectra, which indicate that the compound exists
The IR spectra were recorded on a Specord M-80
spectrophotometer (mulls in mineral oil). The 1H
NMR spectra were taken on a Bruker WP-200 spec-
trometer (200 MHz) in DMSO-d6 at 40 C, internal
reference TMS. The mass spectra were recorded on
a Kratos MS-39 spectrometer (ionizing electron ener-
1
1070-3632/04/7411-1763 2004 MAIK Nauka/Interperiodica

1764
ARTAMONOV, PEREVALOV
Cl
Cl
N+2
N
N
N
H2N
N Ph
N Ph
N
COO
CO2H
I
II
Et2N
N
N
OH
Cl
O
+
N
N
N
N
N
N
N
N
N Ph
N Ph
N Ph
CO2H
CO2H
CO2H
III
VI
VIII
Cl
Cl
N
N
Cl
N
N
ClO2S
N Ph
N Ph
+
N
Cl
HO
N
N
N
CO2H
CO2H
N Ph
IV
V
CO2H
VII
gy 70 eV, ionization chamber temperature 220 C,
direct sample inlet).
and 15 ml of concentrated HCl and a solution of
0.28 g of sodium nitrite in 7 ml of water were added.
After 1 h, a solution of 0.5 g of N,N-diethylaniline in
10 ml of absolute ethanol was added to the resulting
diazo salt solution. The mixture was neutralized to
weakly acidic reaction with a saturated solution of
sodium acetate and allowed to stand for 1 h. The pre-
cipitate was filtered off, reprecipitated from acetone,
recrystallized from ethanol, and dried. Yield of III
0.6 g (13%), mp 267 268 C. IR spectrum (mineral
6-Amino-2-phenyl-7-chloro-2H-benzotriazole-4-
carboxylic acid I. A 13-g portion of 3,5-diamino-4-
chloro-2-phenylazobenzoic acid was suspended in
150 ml of isopropyl alcohol, and the mixture was
heated to 50 C. A copper ammine solution prepared
from 63 g of CuSO4 5H2O, 150 ml of 25% aqueous
ammonia, and 70 ml of water was added with stirring.
The mixture was heated to reflux. After 6 h, the
cooled mixture was acidified with 10% HCl to strong-
ly acidic reaction. The precipitate was filtered off,
washed with water, dried, and recrystallized from
glacial acetic acid. Yield of I 14.3 g (69%), mp 283
1
1
oil), , cm : 1700 (C=O). H NMR spectrum, , ppm
(J, Hz): 8.55 s (1H, H5), 8.35 d (2H, H2 ,6 , 8.0),
7.72 d (2H, H2 ,6 , 10.0), 7.61 7.55 m (3H, H3 ,4 ,5 ),
6.85 d (2H, H3 ,5 , 10.0), 3.50 d (4H, 2CH2, 6.9),
1.18 t (6H, 2CH3, 6.9). Found, %: C 61.33; H 4.70;
N 18.56. M 448. C23H21ClN6O2. Calculated, %: C
61.54; H 4.72; N 18.72. M 448.
1
284 C. IR spectrum (mineral oil), , cm : 3400,
1
3460 (NH2), 1700 (C=O). H NMR spectrum, , ppm
(J, Hz): 8.17 d (2H, H2 ,6 , 8.0), 7.82 s (1H, H5), 7.58
7.46 m (3H, H3 ,4 ,5 ), 6.12 br.s (2H, NH2). Found, %:
C 54.17; H 3.09; N 19.53. M 288. C13H9ClN4O2.
Calculated, %: C 54.09; H 3.14; N 19.41. M 288.
7-Chloro-6-chlorosulfonyl-2-phenyl-2H-benzo-
triazole-4-carboxylic acid IV and 6,7-dichloro-2-
phenyl-2H-benzotriazole-4-carboxylic acid V. A 1-g
portion of 6-amino-2-phenyl-7-chloro-2H-benzotri-
azole-4-carboxylic acid was dissolved with heating in
80 ml of glacial acetic acid. The solution was cooled,
and 15 ml of concentrated HCl and a solution of
0.28 ml of sodium nitrite in 7 ml of water were added.
7-Chloro-6-(4 -N,N-diethylanilinophenylazo)-2-
phenyl-2H-benzotriazole-4-carboxylic acid III. A
1-g portion of 6-amino-2-phenyl-7-chloro-2H-benzo-
triazole-4-carboxylic acid was dissolved with heating in
80 ml of glacial acetic acid. The solution was cooled,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

DIAZOTIZATION OF 6-AMINO-2-PHENYL...
1765
After keeping for 1 h, the solution of the diazo salt
was added to 20 ml of a 30% solution of SO2 in
glacial acetic acid, and a concentrated aqueous solu-
tion of 0.1 g of CuCl2 2H2O was added. Warming of
the mixture was prevented by cooling with ice-cold
water. The reaction was complete in 10 min. The mix-
ture was diluted with water and filtered; the precipitate
was dried and recrystallized from glacial acetic acid.
A mixture of IV and V (0.7 g) was obtained. Com-
pound IV, M+ 372; compound V, M+ 308. IR spec-
was filtered off, washed with water, dried, and recrys-
tallized two times from ethanol. Yield of VII 1.10 g
(37%), mp 246 247 C. IR spectrum (mineral oil), ,
cm : 1700 (C=O). Found, %: C 61.33; H 4.70; N
18.56. M 425. C23H15N5O4. Calculated, %: C 64.94;
H 3.55; N 16.46. M 425.
1
7-Hydroxy-2-phenyl-2H-benzotriazole-4-carb-
oxylic acid VIII. a. A 0.2-g portion of 6-diazo-7-
oxo-2-phenyl-2H-benzotriazole-4-carboxylic acid VI
was dissolved in 50 ml of ethanol, and 0.10 g of
CuSO4 5H2O was added. The mixture was refluxed
for 6 h, cooled, brought to a weakly acidic reaction,
and filtered. The reaction product crystallized from
the filtrate; it was filtered off and dried in air. Yield of
VIII 0.04 g (22%).
1
trum (mineral oil), , cm : 1180, 1380 (SO2Cl),
1
1700 (C=O). Compound IV: H NMR spectrum, ,
ppm (J, Hz): 8.69 s (1H, H5), 8.33 d (2H, H2 ,6 , 8.0),
1
7.74 7.59 m (3H, H3 ,4 ,5 ). Compound V: H NMR
spectrum, , ppm (J, Hz): 8.33 d (2H, H2 ,6 , 8.0),
8.15 s (1H, H5), 7.74 7.59 m (H3 ,4 ,5 ). As judged
from the ratio of the integral intensities of the H5
signals, the relative content of IV and V in the mix-
ture is 65 and 35%, respectively.
b. To a suspension of 1 g of VI in 100 ml of ethan-
ol, 5 ml of a 50% NaOH solution was added, and the
mixture was refluxed for 1 h. After cooling, the mix-
ture was acidified with 10% HCl to a weakly acidic
reaction. The precipitate was filtered off, washed with
water, dried in air, and recrystallized from 80% aque-
ous acetic acid. Yield of VIII 0.3 g (33%), mp 203
6-Diazo-7-oxo-2-phenyl-2H-benzotriazole-4-car-
boxylic acid VI. a. A 1-g portion of I was suspended
in 20 ml of 96% sulfuric acid and 15 ml of water.
A solution of 0.48 g of sodium nitrite in 10 ml of
water was added in portions. Diazotization was per-
formed with stirring at 60 C, until the starting com-
pound disappeared. After cooling, the mixture was
poured into 10% NaOH; the precipitate was filtered
off, washed with water, and dried. Yield of VI 0.74 g
(76%).
1
204 C. IR spectrum (mineral oil), , cm : 3600,
1
3400 (OH), 1690 (C=O). H NMR spectrum, , ppm
(J, Hz): 11.60 br.s (1H, OH), 8.32 d (2H, H2 ,6 , 7.4),
8.04 d (1H, H6, 8.32), 7.73 7.57 m (3H, H3 ,4 ,5 ),
6.81 d (1H, H5, 8.32). Found, %: C 61.23; H 3.48;
N 16.43. M+ 255. C13H9N3O3. Calculated, %: C
61.18; H 3.55; N 16.46. M+ 255.
b. A 1-g portion of I was dissolved with heating in
80 ml of glacial acetic acid. The solution was cooled,
and 5 ml of concentrated HCl was added. A solution
of 0.28 g of sodium nitrite in 20 ml of water was
added dropwise at room temperature. After 1 h, excess
acetic acid was distilled off on a rotary evaporator, the
solution was neutralized with 10% sodium carbonate
to pH 6, the mixture was diluted with water, and the
precipitate was filtered off, washed with water, and
dried in air. Yield of VI 0.65 g (67%), mp 200
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201 C. IR spectrum (mineral oil), , cm : 2180
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phenyl-2H-benzotriazole-4-carboxylic acid VII. A
suspension of 2 g of 6-diazo-7-oxo-2-phenyl-2H-
benzotriazole-4-carboxylic acid VI in 30 ml of water
was added to a solution of 1 g of 2-naphthol and 2 g
of NaOH in 100 ml of water at room temperature. The
mixture was heated for 2 h at 60 C. The precipitate
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004