SYNTHESIS OF DYES
681
Azo dyes R2C6H4N NC10H5(2-OH)(3-R3)
Compound
Decomp.
UV spectrum,
max, nm (log )
Triazene
no.
R2
R3
R1
R2
no.
point,
C
X
XI
XII
XIII
XIV
XV
XVI
XVII
o-NO2
m-NO2
p-NO2
o-COOH
m-COOH
p-COOH
p-NO2
H
H
H
H
H
H
208
194
244
272
243
301
296
147
545 (3.92, H2SO4)
530 (4.07, H2SO4)
550 (4.28, H2SO4)
510 (3.87, EtOH)
508 (3.76, EtOH)
537 (4.01, EtOH)
420 (3.94, EtOH)
427 (3.82, EtOH)
I
II
o-NO
o-NO
o-NO
p NO
p-NO
p-NO
p-NO
p-NO
o-NO2
m-NO2
p-NO2
o-COOH
m-COOH
p-COOH
p-NO2
III
IV
V
VI
VII
VII
CONHPh
CONHC6H4OCH3-o
p-NO2
p-NO2
azene (I), 1.44 g, was dissolved in 200 ml of acetic
acid (d = 1.07 g/cm3), 3 ml of concentrated sulfuric
acid (d = 1.83 g/cm3) was added, and the mixture was
kept for 5 7 min at 10 C. To the resulting solution
of diazonium salt we added 0.72 g of 2-hydroxynaph-
thalene in 200 ml of 50% aqueous NaOH, and the
mixture was kept for 10 min. The product was filtered
off and thoroughly washed with water and ethanol.
Yield 1.28 g (87%), orange red substance, decom-
position point 208 C.
m-(2-Hydroxy-1-naphthylazo)nitrobenzene (XI).
3-Hydroxy-3-(o-nitrosophenyl)-1-(m-nitrophenyl)tri-
azene (II), 1.44 g, was dissolved in 200 ml of acetic
acid (d = 1.07 g/cm3), 50 ml of 1.5% hydrochloric
acid (d = 1.19 g/cm3) was added, and the mixture
was kept for 5 10 min at 10 C. A solution of 0.72 g
of 2-hydroxynaphthalene in 200 ml of 50% aqueous
NaOH was added. The resulting dye was filtered off
and washed with water and ethanol. Yield 1.31 g
(89%), orange substance, decomposition point 194 C.
p-(2-Hydroxy-1-naphthylazo)nitrobenzene (XII)
was synthesized as described above for compound XI
from 1.44 g of 3-hydroxy-3-(o-nitrosophenyl)-1-
(p-nitrophenyl)triazene (III). Yield of XII 1.33 g
(90%), red substance, decomposition point 244 C.
o-(2-Hydroxy-1-naphthylazo)benzoic acid
(XIII). 3-Hydroxy-1-(o-carboxyphenyl)-3-(p-nitroso-
phenyl)triazene (IV), 1.43 g, was dissolved in 30 ml
of acetic acid (d = 1.07 g/cm3), 20 ml of 1.5% hydro-
chloric acid (d = 1.19 g/cm3) was added, and the
mixture was kept for 5 min at 5 C. A solution of
0.72 g of 2-hydroxynaphthalene in 60 ml of 30%
aqueous sodium hydroxide was then added, and the
product was filtered off and washed with water.
Recrystallization from ethanol gave 1.38 g (96%) of
azo dye XIII as a red substance with decomposition
point 272 C [9].
m-(2-Hydroxy-1-naphthylazo)benzoic acid (XIV)
was synthesized as described above for compound
XIII from 1.43 g of 3-hydroxy-3-(p-nitrosophenyl)-
1-(m-carboxyphenyl)triazene (V). Recrystallization
from ethanol gave 1.29 g (88%) of reddish yellow
azo dye XIV, decomposition point 243 C.
p-(2-Hydroxy-1-naphthylazo)benzoic acid (XV)
was synthesized as described above for compound
XIII from 1.43 g of 3-hydroxy-1-(p-carboxyphenyl)-
3-(p-nitrosophenyl)triazene (VI). Yield 1.34 g (91%),
red substance, decomposition point 301 C.
1-(4-Nitrophenylazo)-2-hydroxynaphthalene-3-
carboxanilide (XVI). 3-Hydroxy-3-(p-nitrosophenyl)-
1-(p-nitrophenyl)triazene (VII), 1.44 g, was dissolved
in 200 ml of acetic acid (d = 1.07 g/cm3), 50 ml of
1.5% hydrochloric acid (d = 1.19 g/cm3) was added,
and the mixture was kept for 7 min at 10 C. A solu-
tion of 1.32 g of 3-hydroxynaphthalene-2-carboxani-
lide in 200 ml of 50% aqueous sodium hydroxide was
added, and the product was filtered off and washed
with water. Yield 1.92 g (92%), claret substance,
decomposition point 296 C [10].
2-Hydroxy-1-(4-nitrophenylazo)-N-(o-methoxy-
phenyl)naphthalene-3-carboxamide (XVII) was
synthesized as described above for compound XVI
from 1.44 g of 3-hydroxy-3-(p-nitrosophenyl)-1-(p-
nitrophenyl)triazene (VII). Coupling with 1.47 g
of 3-hydroxy-N-(o-methoxyphenyl)naphthalene-2-
carboxamide gave 1.86 g (84%) of orange red azo dye
XVII, decomposition point 147 C.
In all experiments, acidification of the filtrates
resulted in precipitation of crystals of o- or p-benzo-
quinone dioxime. The precipitate was filtered off,
washed with water, and recrystallized from ethanol.
p-Benzoquinone dioxime, mp 243 C; published data
[10]: mp 243 C; o-benzoquinone dioxime, mp 143 C;
published data [11]: mp 143 C.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 5 2001