Synthesis and transformations of 2-hydroxy-3-arylazo-1,4-naphthoquinones

Article abstract of DOI:10.1023/A:1015429803432

A series of 2-hydroxy-3-arylazo-1,4-naphthoquinones were prepared by coupling of 2-hydroxy-1,4-naphthoquinone with aryldiazonium chlorides. The reactivity of the products toward electrophilic and nucleophilic agents was studied. In reaction with o-phenylenediamine they give condensation products, the corresponding benzo[a]phenazines.

Full text of DOI:10.1023/A:1015429803432

Russian Journal of General Chemistry, Vol. 72, No. 2, 2002, pp. 251 254. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 2, 2002,
pp. 272 275.
Original Russian Text Copyright
2002 by Romanyuk, Polishchuk, Litvin, Ganushchak.
Synthesis and Transformations
of 2-Hydroxy-3-arylazo-1,4-naphthoquinones
A. L. Romanyuk, O. P. Polishchuk, B. L. Litvin, and N. I. Ganushchak
Franko State University, Lviv, Ukraine
Barva Company, Ivano-Frankovsk, Urkaine
Received August 11, 2000
Abstract A series of 2-hydroxy-3-arylazo-1,4-naphthoquinones were prepared by coupling of 2-hydroxy-
1,4-naphthoquinone with aryldiazonium chlorides. The reactivity of the products toward electrophilic and
nucleophilic agents was studied. In reaction with o-phenylenediamine they give condensation products,
the corresponding benzo[a]phenazines.
Aromatic diazonium salts react with 2-hydroxy-
1,4-naphthoquinones [1, 2] and 2-amino-1,4-naph-
thoquinones [3] to give the corresponding 2-
hydroxy-3-arylazo-1,4-naphthoquinones I. How-
ever, the properties of compounds I were not stud-
ied.
According to [1], azo coupling of 2-hydroxy-1,4-
naphthoquinone occurs in an acidic medium, whereas
in a basic medium the initial quinone undergoes aryla-
tion to give the corresponding 2-hydroxy-3-aryl-1,4-
naphthoquinones. Reactions of 2-amino-1,4-naphtho-
quinones with aromatic diazonium salts were also per-
formed in acidic medium [3] assuming that the first
stage of the reaction is hydrolysis of aminonaphtho-
quinone to hydroxynaphthoquinone [3].
cal properties of the resulting azo compounds I are
listed in Table 1.
The electronic absorption spectra of the synthesized
compounds show absorption maxima in the range
413.5 451.5 nm, with the molar extinction coeffi-
1
1
cients ranging from 6 103 to 19.8 104 l mol cm .
Compounds I with electron-donating substituents at
the o- and p-positions of the arylazo moiety exhibit
a red shift of max, whereas with electron-withdraw-
Although azo derivatives of 2-hydroxy-1,4-naph-
thoquinones were reported, their spectral characteris-
tics and reactivity toward electrophiles and nucleo-
philes are virtually unknown.
ing substituents at the o- and p-positions
is
max
blue-shifted. Substituents at the m-position affect
insignificantly.
max
1
In the H NMR spectra of 2-hydroxy-3-arylazo-1,4-
We have studied the reaction of 2-hydroxy-1,4-
naphthoquinones with aromatic diazonium salts in
a weakly basic medium and found that 2-hydroxy-
3-arylazo-1,4-naphthoquinones are formed in high
yields in water or aqueous alcohol (1 : 1) in the pres-
ence of sodium carbonate or hydrocarbonate. Appar-
ently, azo coupling occurs similarly to reactions of
diazonium salts with compounds containing an active
methylene group. The yields and some physicochemi-
naphthoquinones I, the naphthoquinone ring protons
are manifested as a multiplet at 8.13 8.27 ppm; the
position of the signal from aromatic protons of the
arylazo moiety depends on the nature and position of
substituents in the aromatic ring. The hydroxyl proton
1
gives a signal at about 15 ppm. The H NMR data for
2-hydroxy-3-arylazo-1,4-naphthoquinones are listed in
Table 2.
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252
ROMANYUK et al.
Table 1. Yields and constants of Ia Ik
Comp.
no.
mp,
C
3
1
10 , l mol 1 cm
Ar
Yield, %
max, nm
(solvent for crystallization)
Ia
C6H5
93
66
31
69
76
81
84
72
70
68
55
228 229 (alcohol)
229 229.5 (THF)
134 135 (DMF water)
249 250 (alcohol)
201 201.5 (THF)
167 168 (toluene)
275 276 (toluene)
209 210 (alcohol)
193 194 (alcohol)
224 225 (alcohol)
155 156 (alcohol)
427.0
451.0
451.5
432.5
436.5
413.5
423.0
436.0
431.0
450.5
431.5
19.8
6.60
6.36
5.76
11.04
7.77
5.9
11.17
10
6.14
6.06
Ib
Ic
Id
Ie
If
Ig
Ih
Ii
4-H3COC6H4
4-(CH3)2NC6H4
2-NO2C6H4
4-H3CC6H4
3-NO2C6H4
4-NO2C6H4
2-H3CC6H4
3-H3CC6H4
2-H3COC6H4
3-H3COC6H4
Ij
Ik
Table 2. 1H NMR data for 2-hydroxy-3-arylazo-1,4-naphthoquinones Ia, Ib, Id, and Ie, , ppm
Comp.
no.
H1
H2
H3
OH
Ia
8.214 d (1H), 8.104 d (1H), 7.914 m (2H) 7.766 d (2H), 7.534 t (2H), 7.343 t (1H)
8.208 d (1H), 8.089 d (1H), 7.90 m (2H) 7.75 d (2H), 7.11 d (2H)
15.00 d (1H)
3.823 s (3H) 15.443 s (1H)
15.803, 15.643
Ib
Id
Ie
a
b
8.213 d (1H), 8.10 d (1H), 7.91 m (2H)
7.67 d (2H), 7.34 d (2H)
2.35 s (3H) 15.18 s (1H)
a
b
Overlaps with the signals of the arylazo moiety in the range 8.26 7.93 ppm. Overlaps with the signals of the naphthoquinoid
moiety in the range 8.26 7.93 and at 7.47 ppm (1H).
Table 3. Yields, constants, and elemental analyses of IIa IIc
3
Comp.
no.
10 ,
R
mp, C
Yield, %
max, nm
Found N, %
Formula
Calculated N, %
l mol 1 cm
1
IIa
IIb
IIc
H
4-CH3
2-NO2
258 259
238 239
277 278
63
74
80
465
454
475
17.6
7.75
4.52
15.81
15.32
17.54
C22H14N4O
C23H16N4O
C22H13N5O3
16.00
15.38
17.72
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002

SYNTHESIS AND TRANSFORMATIONS OF 2-HYDROXY-3-ARYLAZO-1,4-NAPHTHOQUINONES 253
In the IR spectra of compounds I, the hydroxy
thoquinones, we performed their reactions with nucle-
ophilic and electrophilic agents, in particular, with
o-phenylenediamine, aniline, benzoyl chloride, and
benzenesulfonyl chloride. Reactions of compounds I
with o-phenylenediamine yield the condensation prod-
ucts, substituted benzo[a]phenazines II. The constants,
yields, and elemental analyses of IIa IIc are listed in
Table 3.
group gives two weak broad bands at 3500 3380 and
1
approximately 1115 cm . The vibrations of two car-
bonyl groups are manifested as a single broad band
1
at about 1715 cm .
To study the reactivity of the electrophilic and
nucleophilic centers in 2-hydroxy-3-arylazo-1,4-naph-
R = H (a), 4-CH3 (b), 2-NO2 (c).
It is known that molecules with quinoid fragments
show tautomerism: the p-quinoid structure can trans-
form into the o-quinoid or dihydro structure [4]. At
the same time, hydroxy azo compounds show azo
hydrazo tautomerism [5]. Therefore, for compounds II
we can suggest formation of four structures A D.
The reaction of I with aniline was performed in
refluxing ethanol for 6 h. No nucleophilic substitution
products were detected. The reactions with benzoyl
chloride and benzenesulfonyl chloride were performed
in pyridine at 50 C; no acylation products were de-
tected.
To determine the structure of condensation prod-
EXPERIMENTAL
1
ucts II, we measured their H NMR and IR spectra.
1
The H NMR spectra of II show a singlet (1H) at
The IR spectra were taken from KBr pellets on a
Specord IR-75 spectrophotometer. The 1H NMR spec-
tra were recorded with a Varian VXR-300 spectrom-
eter (300 MHz, DMSO-d6, external reference HMDS),
and the electronic absorption spectra, on a Shimadzu
UV-1601 spectrophotometer (ethanol solutions).
16.25 ppm. Its position is typical of an enolic proton
[6], which is present in structure B only.
1
The IR spectra in the range 3490 3380 cm con-
1
tain a hydroxyl absorption band. A band at 1670 cm
can be assigned to the C=N stretching vibrations [6].
Thus, reactions of 2-hydroxy-3-arylazo-1,4-naphtho-
quinones with o-phenylenediamine yield 5-hydroxy-6-
arylazobenzo[a]phenazines B.
The product purity was checked by TLC on Silufol
UV-254 plates, eluent acetone hexane, 1 : 1.
2-Hydroxy-3-phenylazo-1,4-naphthoquinone Ia.
To 0.93 g of aniline we added 4 ml of concentrated
HCl and 2 ml of water. After the amine dissolved, the
mixture was cooled to 0 C, and a solution of 0.7 g of
NaNO2 in 3 ml of water was added; in the process,
As expected, in the electronic absorption spectra of
IIa IIc
is shifted bathochromically relative to
compoundmsaxI, but the molar extinction coefficient
changes insignificantly (Table 3).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002

254
ROMANYUK et al.
the reaction temperature was kept below 5 C. To the
resulting solution of the aryldiazonium salt, sodium
hydrocarbonate was added in small portions at 0 5 C
with continuous stirring. Immediately after the solu-
tion became weakly acidic, a solution of 1.74 g of
2-hydroxy-1,4-naphthoquinone and 0.84 g of NaHCO3
in 15 ml of water was added. The mixture was stirred
for 1 1.5 h, after which the mixture was acidified
with dilute HCl. The precipitate was filtered off and
washed with water. Red crystals were obtained; yield
2.58 g (93%), mp 228 229 C (from ethanol). IR spec-
1500 (arom. ring), 1440 (N=N), 1115 (O H). 1H
NMR spectrum, , ppm: 16.25 s (1H), 8.78 d (1H),
8.39 m (1H), 8.28 d (1H), 8.15 m (1H), 7.89 m,
7.77 m (total 9H), 7.54 m (2H), 7.28 m (1H).
Compounds IIb and IIc were prepared similarly.
REFERENCES
1. Zollinger, H., Chemie der Azofarbstoffe, Basel:
Birkhauser, 1958. Translated under the title Khimiya
azokrasitelei, Porai-Koshits, B.A., Ed., Leningrad:
Goskhimizdat, 1960, p. 101.
1
trum, , cm : 3470 3380 (O H), 3095 (C H arom.),
1710 (C=O), 1625 (C=C in quinone), 1520 (arom.),
1400 (N=N), 1115 (O H).
2. Fieser, L., J. Am. Chem. Soc., 1948, vol. 70, p. 3203.
3. Grinev, A.N., Venevtseva, N.K., and Terent’ev, A.P.,
Compounds Ib Ik were prepared similarly.
Zh. Obshch. Khim., 1960, vol. 30, no. 1, pp. 183 185.
4. Litvin, B.L., Kolesnikov, V.T., Kopel’tsiv, Yu.A., and
Yarish, M.E., Zh. Org. Khim., 1986, vol. 22, no. 1,
pp. 140 146.
2-Hydroxy-6-phenylazobenzo[a]phenazine IIa.
A solution of 0.81 g of o-phenylenediamine in 25 ml
of ethanol was added to a suspension of 1.39 g of
2-hydroxy-3-phenylazo-1,4-naphthoquinone in 100 ml
of ethanol. The mixture was refluxed for 2 h and
cooled; the precipitate was filtered off, washed with
alcohol, and recrystallized from DMF. A red product
was obtained; yield 1.1 g (63%), mp 258 259 C. IR
5. Gordon, P.F. and Gregory, P., Organic Chemistry in
Colour, Berlin: Springer, 1987.
6. Ioffe, B.V., Kostikov, R.R., and Razin, V.V., Fizi-
cheskie metody opredeleniya organicheskikh soedinenii
(Physical Methods for Determination of Organic Com-
pounds), Moscow: Vysshaya Shkola, 1984, pp. 308,
315.
1
spectrum, , cm : 3490 3380 (O H), 3085 (C H
arom.), 1670 (C=N), 1610 (N=N of quinone), 1545,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002