1H,6H-Triazolo[4,5-e]benzotriazole-3-oxides and 5,5′-(Z)-diazene-1,2-diylbis(2-methyl-2H-1,2,3-benzotriazole) derived from chloronitrobenzotriazoles and hydrazine

Article abstract of DOI:10.3987/COM-05-10481

Nitration of 5-chlorobenzotriazole (1) and its N1-methyl derivatives (2 and 3) produced 5-chloro-4-nitrobenzotriazole (5), 5-chloro-1-methyl-4-nitrobenzotriazole (6) and 6-chloro-1-methyl-7-nitrobenzotriazole (7) respectively. Nitration of 5-chloro-2-methylbenzotriazole (4) gave either 5-chloro-2-methyl-4-nitrobenzotriazole (8) or 5-chloro-2-methyl-4,6-dinitrobenzotriazole (9). Introduction of the nitro group activated chlorine atom that underwent nucleophilic displacement by hydrazine to give rise to a new tricyclic system 1H,6H-triazolo[4,5-e]benzotriazole-3-oxide compounds (10 and 11) in the case of 5 and 6. From 9 no linear or angular tricyclic triazolobenzotriazole was obtained but instead the 5,5′-(Z)-diazene-1,2-diylbis(2-methyl-2H-1,2,3-benzotriazole) (18).{A figure is presented}.

Full text of DOI:10.3987/COM-05-10481

HETEROCYCLES, Vol. 65, No. 10, 2005
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HETEROCYCLES, Vol. 65, No. 10, 2005, pp. 2471 - 2481
Received, 16th June, 2005, Accepted, 15th August, 2005, Published online, 23rd August, 2005
1
H,6H-TRIAZOLO[4,5-e]BENZOTRIAZOLE-3-OXIDES AND 5,5’-(Z)-
DIAZENE-1,2-DIYLBIS(2-METHYL-2H-1,2,3-BENZOTRIAZOLE)
DERIVED
FROM
CHLORONITROBENZOTRIAZOLES
AND
HYDRAZINE
Antonio Carta,* Sandra Piras, Gianpiero Boatto, and Giuseppe Paglietti
Department of Medicinal and Toxicological Chemistry, University of Sassari, Via
Muroni 23, 07100 Sassari, Italy
Abstract – Nitration of 5-chlorobenzotriazole (1) and its N1-methyl derivatives (2
and 3) produced 5-chloro-4-nitrobenzotriazole (5), 5-chloro-1-methyl–4-
nitrobenzotriazole (6) and 6-chloro-1-methyl–7-nitrobenzotriazole (7) respectively.
Nitration of 5-chloro-2-methylbenzotriazole (4) gave either 5-chloro-2-methyl-4-
nitrobenzotriazole (8) or 5-chloro-2-methyl-4,6-dinitrobenzotriazole (9).
Introduction of the nitro group activated chlorine atom that underwent nucleophilic
displacement by hydrazine to give rise to a new tricyclic system 1H,6H-
triazolo[4,5-e]benzotriazole-3-oxide compounds (10 and 11) in the case of 5 and 6.
From 9 no linear or angular tricyclic triazolobenzotriazole was obtained but
instead the 5,5’-(Z)-diazene-1,2-diylbis(2-methyl-2H-1,2,3-benzotriazole) (18).
1
,2
Benzotriazole continues to receive a deal of interest for its versatility as synthetic auxiliary. However,
little attention has been paid for the reactions of electrophilic substitution on the benzene counterpart
unless these compounds were necessary as intermediates in building block of heterocyclic systems. This
is our case that for years we pursued the goal to obtain novel triazoloquinolines, triazoloquinoxalines of
3
-11
12-18
pharmaceutical interest
and to study the chemistry of benzotriazole
and its derivatives endowed
1
9-27
with pharmacological activities.
It is well known that electrophilic substitution reactions (halogenation and nitration) on benzotriazole and
its N-alkyl derivatives have not been widely used because the triazole acts as a deactivating group on the
benzene ring and orientation is largely influenced by both the nature and position of the substituents
giving rise to 4- or 5- ring substituted benzotriazoles. Thus, the standard methods of synthesis involve
cyclization of substituted 1,2-diaminobenzenes by means of nitrous acid. In the past some of us adopted

2472
HETEROCYCLES, Vol. 65, No. 10, 2005
this procedure to prepare several unambiguous 5-monosubstitued or 5,7(4,6)-disubstituted N1(N3)-
1
2
alkylbenzotriazole isomers. Successively, when 5-nitrobenzotriazole became commercially unavailable,
2
8
we had to re-examine the nitration reaction of benzotriazole as reported by Fries et al. and Miller and
2
9
Wagner and we discovered that the 4-nitro isomer was mainly formed (58% yield) but it was
accompanied by the 15% yield of the 5-nitro ones. This result is described now for the first time and
3
0
seems in accordance with the observations of Kamel et al. for the case of the nitration of 2-
methylbenzotriazole which led to a similar mixture of 2-methyl-4-nitro- and 2-methyl-5-
nitrobenzotriazoles. The situation can be different when an appropriate substituent is already present in
the benzene moiety. This is the case we have examined in the present paper in which all previously
1
2
known 5-chloro-1H-benzotriazole (1) and its three N-methyl derivative isomers (2, 3 and 4) underwent
nitration according to Scheme 1.
CH3
H
N
iv
N
N
N
8
9
N
N
+
90%
iii
N
+
N
N
N
CH3
i
N
Cl
N
(25%)
Cl
Cl
Cl
1
2
3
(30%)
CH3
95%
4 (26%)
ii
ii
ii
CH3
H
N
ii
N
N
N
N
N
N
N
N
Cl
Cl
Cl
NO2
CH3
NO2
(96%)
NO2
5
(99%)
6
O2N
Cl
7
(79%)
N
N
N
N
N
CH3
N
CH3
iii
Cl
NO2
9
NO2
8
ii) 70%
ii) 17%; iii) 95%
3 2 4 2 4 3
i) (CH ) SO , NaOH, rt, 90 min. ii) H SO , KNO , 50 °C, 2.5 h.
iii) H SO , KNO , 50 °C, 14 h. iv) H SO , KNO , rt, 2 h.
2
4
3
2
4
3
Scheme 1
These new ortho-chloronitrobenzotriazoles (5, 6, 7, 8) were then submitted to nucleophilic displacement
of chlorine by hydrazine hydrate in order to prepare 1H,6H(7H)(8H)-triazolo[4,5-e]benzotriazole-3-
oxides (10, 11, 12 and 13) of Scheme 2 for pharmacological studies.
N-Methyl isomers (2, 3 and 4) of 5-chloro-1H-benzotriazole (1) were prepared as previously described on
1
2
alkylation with dimethyl sulfate in alkaline medium with an overall yield of 76% of pure isomers.
Compounds (1, 2 and 3) separately underwent mononitration at position C-4 in excellent yields carrying

HETEROCYCLES, Vol. 65, No. 10, 2005
2473
out the reaction in sulfuric acid and potassium nitrate at 50°C for 2.5 h. Under the same conditions from
compound (4) we isolated both 5-chloro-2-methyl-4-nitrobenzotriazole (8) and 5-chloro-2-methyl-4,6-
dinitrobenzotriazole (9) in the ratio of about 4:1. When the reaction was carried out at room temperature,
the sole compound (8) was isolated in 90% yield, whereas operating at 50°C for 14 h compound (9) was
formed in 95% yield. The latter was straightforward obtained from 8 in an identical yield under the same
conditions. An explanation for mononitration in the case of compounds (1, 2 and 3) may be due to the
concomitant ortho directing effect of both chlorine atom and triazole group.
In the case of nitration of the isomer (4) it is noteworthy to observe the formation of a mixture of
compounds (8) and (9) in the ratio of 4:1 respectively. However, it must be also pointed out that this
reaction undergoes kinetic versus thermodynamic control showing a certain analogy with the reactivity of
3
0
naphthalene, as previous observed by Kamel et al., although in this case it was very selective since the
triazole ring can’t be nitrated.
Thus, at room temperature for 2 h compound (4) was transformed into 8 in 90% yield, whereas at 50°C
for 14 h the dinitro compound (9) was formed in 95% yield. It seems reasonable to think that this
behavior is strongly favoured by the concomitant ortho meta directing effects of both chlorine/triazole
and nitro groups respectively. In addition it must be noted that our attempt at nitrating of the mononitro
isomers (6 and 7), under the same conditions as above, was not successful and the starting compounds
were fully recovered. This would account for the influence of the different position of the substituent on
triazole ring.
At this stage it was interesting to study the activating effects of nitro group towards the nucleophilic
displacement of chlorine atom by hydrazine hydrate for a ring closure into a triazole N-oxide. Therefore,
we have submitted the mononitro compounds (5-8) to reaction with an excess of hydrazine hydrate
according to the conditions depicted in Scheme 2, previously experienced by us in the case of chloro-
9
-11
nitroquinolines.
This procedure was only partially successful for we were able to isolate the 1H,6H-triazolo[4,5-
e]benzotriazole-3-oxides (10) (80 %) and (11) (33 %) but none of the expected (12) and (13). In the
attempt to obtain also the derivatives (12) and (13) we repeated the same reaction on compounds (7) and
3
1
(
8) in a sealed steel vessel at 70°C for 90 h. Unfortunately, only the previously described 1-
methylbenzotriazole (14) (32 %) and 2-methylbenzotriazole (15) (30 %) were respectively isolated.
An explanation of the different reactivity of 7 and 8 in comparison with that of 5 and 6 may be due to the
position of the methyl group on the N3 or N2 of triazole ring in 7, 8 where, owing to the resonance forms,
the presence of a positive charge on these nitrogen atoms is counterbalanced by a further negative charge
on the nitro group which decreases its withdrawing effect.

2474
HETEROCYCLES, Vol. 65, No. 10, 2005
N
N
N
H
O 10a
H N
N
N
H
N
H
N
N
N
i
N
N
Cl
H N
NO2
5
N
N
O
1
0 (80%)
CH3
CH3
N
N
N
N
N
N
i
Cl
H N
NO2
6
N
N
O
1
1 (33%)
N
N
N
N
N
N
N
N
N
ii
i
Cl
H N
CH3
4 (32%)
CH3
CH3
NO2
7
N
N
1
O
1
2
N
N
N
N CH3
N CH3
i
N CH3
ii
N
N
N
Cl
H N
1
5 (30%)
NO2
8
N
N
O
1
3
i) H
2
N-NH
2
, CH
3
2 2 2 3 2
CH OH, reflux, 30 h. ii) H N-NH , CH CH OH (sealed steel vessel), 70 °C, 90 h.
Scheme 2
In this way chlorine atom at position C-5 resulted more stable towards the nucleophile. In addition, in the
case of 7, steric hindrance of N3-methyl group might play a negative effect for the substitution reaction.
In the light of this result we have to think that because this type of reaction does not take place even under
more drastic conditions the hydrazine would behave as strongly reducing agent to cause displacement of

HETEROCYCLES, Vol. 65, No. 10, 2005
2475
both chlorine and nitro group up to give rise to the above mentioned 1-methylbenzotriazole (14) and 2-
methylbenzotriazole (15).
Confirmation of the role played by the electronreleasing effects of the methyl group on triazole nitrogen
may come from the great difference in the yields recorded in the formation of 10 (80%) against that of 11
(
33%) and in no formation of 12 and 13.
We have also examined the reaction of 9 with hydrazine hydrate in refluxing ethanol since from this
compound it would be reasonable to expect either a linear or angular ring closure to give 17 and/or 16.
Interestingly, the only compound isolated was the azocompound (18) in 47% yield (Scheme 3) that seems
to exclude any chance of formation of a tricyclic system.
O
N
N
N
N CH3
N
H
N
NO2 17
N
N
N CH3
N
N
O N
2
N
N
N CH3
N
18 (47%)
H N
N
CH3
H NNH
CH3CH2OH
reflux
30 h
2
2
N
N N
16
O
O N
2
N
N
N CH3
Cl
NO2
9
Scheme 3
No apparent reason out of a susceptibility of the nitro groups to the reducing conditions as experienced in
the above cases of 7 and 8 accounts for the formation of 18, that is supported by its analytical data and
NMR spectra, via the suggested mechanism of Figure 1.
In our opinion the strongly activated chlorine atom would force the reaction of 2 moles of 9 with one
mole of hydrazine to form the intermediate (19). Then the excess of base would displace the adjacent
3
2
nitro groups in analogy with other described cases of dinitrobenzenes. Successive oxidation of hydrazo

2476
HETEROCYCLES, Vol. 65, No. 10, 2005
to azo compound should be favoured by ortho quinonoid form of the benzotriazole moiety. All the
1
structures of the described compounds were proved by the analytical data and H-NMR spectra.
O N
2
N
N
N
CH3
O N
2
N
N
H NNH /EtOH
2
2
H
N
N
N
CH3
O2N
-2 HCl
H NO2
Cl
N
NO2
9
N
NO2
CH3
N
O N
2
N
N
N
CH3
N
N
H
H
NO2
O N
2
N
NO2
N
CH3
N
1
9
H2 (From H2NNH2)
2 HNO2
-
N
O N
2
N
N
N
CH3
N
N
CH3
N
N
H2
2 HNO2
N
N
O N
2
-
N
18
N
N
CH3
N
N
CH3
N
Figure 1
In particular the UV spectra were recorded to observe whatsoever influence of the nitro group on the
starting 5-chlorobenzotriazoles. Compounds (6) and (7) exhibited very similar chromophores. The longest
wavelength peaks appears between 270-280 nm while a second lowest peak appears between 250-240 nm.
In the 2-methyl isomer (8) two very close maxima were recorded at 278, 272 nm. In comparison with the
1
2
reported spectra of their precursors (2, 3 and 4) it must be noted that the extinction coefficients of the
maxima at shortest wavelength (250-240 nm) in (6) and (7) resulted much lower than those at higher
wavelength, where in compound (8) this difference could not be noted. From these data it is clear that the
influence of the nitro group on the chromophore produced a very little hypsochromic effect. In the
tricyclic compounds (10) and (11) does not seem to be present any characteristic difference. However,
compound (11) in very concentrated solution exhibited a certain analogy with the spectra of

HETEROCYCLES, Vol. 65, No. 10, 2005
2477
12
naphthotriazole previously reported. The azo compound (18) did show a maximum at 274 nm as recorded
in the above reported other cases while we could observe a hyperchromic effect on the peak at 232 nm.
In conclusion, from our experiments it emerges an easy and quite convenient synthesis of benzo[1,2-
d:3,4-d’]bis-1,2,3-triazolo 1-oxides (10 and 11) as well as that of 5,5’-(Z)-diazene-1,2-diylbis(2-methyl-
2
H-1,2,3-benzotriazole) (18) starting from the commercially available 5-chlorobenzotriazole.
EXPERIMENTAL
Melting points are uncorrected and were taken in open capillaries in a Digital Electrothermal IA9100
1
melting point apparatus. H-NMR spectra were recorded at 200 MHz using a Varian XL-200
spectrometer. Chemical shifts are reported in ppm (δ) relative to tetramethylsilane as internal standard.
MS spectra were performed on a combined HP 5790 (GC)-HP 5970 (MS) apparatus or with a combined
Liquid Chromatograph-Agilent 1100 series Mass Selective Detector (MSD). Column chromatography
was performed using 70-230 mesh (Merck silica gel 60). The progress of the reactions and the purity of
the final compounds were monitored by TLC using Merck F-254 commercial plates. Light petroleum
refers to the fraction with bp 40-60°C.
Nitration of 1H-benzotriazole
To a solution of benzotriazole (20 g, 168 mmol) in sulfuric acid (97-98 %) (68 mL), externally cooled
with an iced bath, conc. nitric acid (17 mL, d=1.51) was slowly added taking care that the temperature did
not exceed 30°C. Then the mixture was allowed to reach rt and stirred for an additional hour. Finally the
reaction mixture was poured onto water and crushed ice (150 mL) to give a solid that was collected (25.4
g).
Tlc showed two spots. Crystallization of the crude mixture from acetone gave 16 g (58%) of 4-
2
8
nitrobenzotriazole, mp 230-232°C identical with an authentic specimen described by Fries et al. and
2
9
Miller and Wagner. From the mother liquors on evaporation it was obtained a mixture of two
compounds.
This was then chromatographed on silica gel column eluting with ether to give in the order: 3.1 g of an
inseparable mixture of 4- and 5-nitrobenzotriazoles and in the end 4 g (15%) of 5-nitrobenzotriazole, mp
3
3
2
10-211°C identical with an authentic specimen as described by Zincke et al.
Preparation of 5-chloro-1-methylbenzotriazole (2), 6-chloro-1-methylbenzotriazole (3) and 5-
chloro-2-methylbenzotriazole (4)
To commercially available (Aldrich) 5-chlorobenzotriazole (1) (5.0 g, 32.6 mmol) dissolved in 2N NaOH
(65 mL, 130 mmol) methyl sulfate (8.5 mL, 51 mmol) was added at rt under stirring within 30 min.

2478
HETEROCYCLES, Vol. 65, No. 10, 2005
Stirring was continued for an additional 90 min. After then, the crude precipitate formed was purified by
silica gel column chromatography eluting with a mixture of ether/light petroleum in the ratio 8:2. In this
way we obtained in the order:
1
2
1
compound (4) (26 %) as a solid, mp 55-57 °C (ether) [lit., 55.5-57.5 °C]; H-NMR (CDCl
3
): δ 7.84 (d,
1H, J = 1.6 Hz, H-4), 7.79 (d, 1H, J = 9.0 Hz, H-7), 7.33 (dd, 1H, J = 9.0, 1.6 Hz, H-6), 4.50 (s, 3H,
+
3
CH ); MS M/Z 167, 169 (M );
1
2
1
compound (3) (30 %) as a solid, mp 121-123 °C (ether) [lit., 121-123 °C]; H-NMR (CDCl
3
): δ 7.97 (d,
1H, J = 8.8 Hz, H-7), 7.54 (d, 1H, J = 1.6 Hz, H-4), 7.34 (dd, 1H, J = 8.8, 1.6 Hz, H-6), 4.28 (s, 3H,
+
3
CH ); MS M/Z 167, 169 (M );
1
2
1
compound (2) (25 %) as a solid, mp 90-92 °C (ether) [lit., 97-99 °C]; H-NMR (CDCl ): δ 8.02 (d, 1H,
3
+
J = 1.4 Hz, H-4), 7.47-7.45 (m, 2H, H-6 + H-7), 4.30 (s, 3H, CH
Assignment of the exact structure for the isomers (2-4) came by application of nuclear Overhauser effect
nOe) procedure.
3
); MS M/Z 167, 169 (M ).
(
Nitration of the 5-chlorobenzotriazole (1) and its N-methyl derivatives (2-4)
ii (Scheme 1). KNO (3.0 g, 30 mmol) in 15 mL of sulfuric acid (97-98 %) was dropwise added at rt to a
3
stirred solution of the appropriate benzotriazole (1-4) (9 mmol) in 15 mL of sulfuric acid (97-98 %). Then,
the reaction was heated at 50 °C and the stirring continued for additional 2.5 h. On cooling, the reaction
mixture was poured into ice (100 mL) and the crude precipitate obtained was washed with water, and
collected by filtration to afford the corresponding derivatives (5-7). In the case of compound (4) it was
obtained a mixture of nitro derivatives (8/9) which was purified by flash chromatography on silica gel
using ether as eluent. Yields, melting points, analytical and spectroscopical data are reported below.
5
-Chloro-4-nitrobenzotriazole (5) (from 1) (99 % yield); mp 215-217 °C (acetone); UV(EtOH): 286
1
nm; H-NMR (CDCl
3
+DMSO-d
6
): δ 16.50 (br s, 1H, NH), 8.24 (d, 1H, J = 8.6 Hz, H-7), 7.60 (d, 1H, J =
+
8
3
5
2
2
6
2
.6 Hz, H-6); MS M/Z 198, 200 (M ); Anal. Calcd for C H N O Cl: C, 36.29; H, 1.52; N, 28.22. Found C,
6
3
4
2
6.03; H, 1.65; N, 27.92.
-Chloro-1-methyl-4-nitrobenzotriazole (6) (from 2) (96 % yield); mp 125-127 °C (ether); UV(EtOH):
1
74, 255, 250sh nm; H-NMR (CDCl
3 3
): δ 7.70-7.57 (m, 2H, H-6 + H-7), 4.38 (s, 3H, CH ); MS M/Z 212,
+
14 (M ); Anal. Calcd for C
7
H
5
N
4
O
2
Cl: C, 39.55; H, 2.37; N, 26.35. Found C, 39.89; H, 2.21; N, 26.01.
-Chloro-1-methyl-4-nitrobenzotriazole (7) (from 3) (79 % yield); mp 91-93 °C (ether); UV(EtOH):
1
79, 253, 243 nm; H-NMR (CDCl
3
): δ 8.16 (d, 1H, J = 8.8 Hz, H-7), 7.49 (d, 1H, J = 8,8 Hz, H-6), 4.26
+
(
s, 3H, CH ); MS M/Z 212, 214 (M ); Anal. Calcd for C H N O Cl: C, 39.55; H, 2.37; N, 26.35. Found C,
3
7
5
4
2
3
5
9.30; H, 2.50; N, 26.12.
-Chloro-2-methyl-4-nitrobenzotriazole (8) (from 4) (70 % yield); mp 161-163 °C (ether); UV(EtOH):

HETEROCYCLES, Vol. 65, No. 10, 2005
2479
1
2
3
4
5
78, 272 nm; H-NMR (CDCl ): δ 8.01 (d, 1H, J = 9.0 Hz, H-7), 7.48 (d, 1H, J = 9.0 Hz, H-6), 4.58 (s,
3
+
H, CH
3
); MS M/Z 212, 214 (M ); Anal. Calcd for C
7
H
5
N
4
O
2
Cl: C, 39.55; H, 2.37; N, 26.35. Found C,
0.02; H, 2.07; N, 26.30.
-Chloro-2-methyl-4,6-dinitrobenzotriazole (9) (from 4) (17 % yield ); mp 123-125 °C (ether);
1
UV(EtOH): 279, 226 nm; H-NMR (CDCl
3
3
): δ 8.60 (s, 1H, H-7), 4.66 (s, 3H, CH ); MS M/Z 257, 259
+
(
M ); Anal. Calcd for C
7
H
4
N
5
O
4
Cl: C, 32.64; H, 1.57; N, 27.19. Found C, 33.01; H, 1.40; N, 26.92.
iii- Compounds (4) or (8) were submitted to nitration under the same conditions as in ii, but heating was
prolonged for an additional 11.5 h, to afford the derivative (9) pure and in very high yield (95 %).
iv- When compounds (4) was submitted to nitration under the same conditions as in ii, but the reaction
was carried out for 2 h at rt, afforded the derivative (8) pure in high yield (90 %).
Reaction of chloro-methyl-nitrobenzotriazoles (5 - 9) with hydrazine.
Method i (Scheme 2). A mixture of an opportune nitro derivative (5, 6, or 9) (2.5 mmol) and a large
excess of 98 % hydrazine monohydrate (5.25 mL, 108 mmol) in ethanol (25 mL), was refluxed under
stirring for 30 h. The reaction mixture was allowed to reach rt, then the solvent and the excess of
hydrazine were removed in vacuo to give a crude precipitate which was taken up with acetone (25 mL)
and stirred for an additional 30 min. A pure solid was obtained, filtered off and washed with acetone to
give 10, 11 and 18 respectively. Yields, melting points, analytical and spectroscopical data are reported
below.
1
H,6H-Triazolo[4,5-e]benzotriazole-3-oxide (10) (from 5) (80 % yield); mp > 300 °C (ethanol);
1
UV(EtOH): 274 nm; H-NMR (DMSO-d
6
): δ 16.40-16.10 (br s, 2H, 2 NH), 7.97 (d, 1H, J = 9.2 Hz, H-5),
7
.80 (d, 1H, J = 9.2 Hz, H-6); LC/MS: 177 (M+H); Anal. Calcd for C H N O: C, 40.91; H, 2.29; N, 47.71.
6 4 6
Found C, 40.59; H, 2.44; N, 47.98.
6
-Methyl-1H,6H-triazolo[4,5-e]benzotriazole-3-oxide (11) (from 6) (33 % yield); mp 280-282 °C
1
(
(
ethanol); UV(EtOH): 278sh, 250, 264sh, 230sh,213 nm; H-NMR (DMSO-d
6
): δ 14.28 (s, 1H, NH), 8.08
); LC/MS: 191 (M+H); Anal.
O: C, 44.21; H, 3.18; N, 44.19. Found C, 40.01; H, 3.34; N, 43.90.
d, 1H, J = 8.8 Hz, H-5), 7.84 (d, 1H, J = 8.8 Hz, H-6), 4.43 (s, 3H, CH
3
Calcd for C
7
H
6
N
6
5
,5’-(Z)-Diazene-1,2-diylbis(2-methyl-2H-1,2,3-benzotriazole) (18) (from 9) (47 % yield); mp 186-
1
1
87 °C (acetone); UV(EtOH): 274, 238sh, 231 nm; H-NMR (DMSO-d
6
): δ 8.87 (d, 2H, J = 2.2 Hz, H-4
+
H-4’), 8.24 (dd, 2H, J = 9.2 e 2.2 Hz, H-6 + H-6’), 7.98 (d, 2H, J = 9.2 Hz, H-7 + H-7’), 4.61 (s, 6H, 2
+
+
3 12 8
CH ); MS M/Z 292 (10 %) (M ), 146 (100 %) (1/2 M ); Anal. Calcd for C14H N : C, 57.53; H, 4.14; N,
38.34. Found C, 57.78; H, 4.31; N, 38.09.

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HETEROCYCLES, Vol. 65, No. 10, 2005
ii- A mixture of nitro derivative (7 - 8) (2.5 mmol) and a large excess of 98 % hydrazine monohydrate
5.25 mL, 108 mmol) in ethanol (100 mL) was heated in a sealed steel vessel at 70°C for 90 h. On cooling,
(
after removal of the solvent and the excess of hydrazine under reduced pressure a crude solid was
obtained. Chromatography on silica gel column eluting with a mixture of light petroleum/ethyl acetate
(
6:4 ratio) gave 1-methylbenzotriazole (14) (32 % yield) from 7 and 2-methylbenzotriazole (15) (30 %
3
1
yield) from 8 respectively which were identical with the authentic specimens previously described.
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