Nucleophilic substitution in 4-bromo-5-nitrophthalodinitrile: V. Synthesis of 5-nitro-4-(4-R-phenoxy)phthalodinitriles and phthalocyanines derived from them

Article abstract of DOI:10.1023/A:1015454508883

A series of aryloxy-substituted phthalodinitriles were prepared by nucleophilic aromatic substitution of bromine in 4-bromo-5-nitrophthalodinitrile, and the corresponding phthalocyanines were synthesized. The physicochemical properties of phthalocyanines depend on the substituent in the aryl moiety.

Full text of DOI:10.1023/A:1015454508883

Russian Journal of General Chemistry, Vol. 72, No. 2, 2002, pp. 307 310. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 2, 2002,
pp. 332 335.
Original Russian Text Copyright
2002 by Balakirev, Maizlish, Shaposhnikov.
Nucleophilic Substitution in 4-Bromo-5-nitrophthalodinitrile:
V.1 Synthesis of 5-Nitro-4-(4-R-phenoxy)phthalodinitriles
and Phthalocyanines Derived from Them
A. V. Balakirev, V. V. Maizlish, and G. P. Shaposhnikov
Ivanovo State University of Chemical Technology, Ivanovo, Russia
Received November 16, 2000
Abstract A series of aryloxy-substituted phthalodinitriles were prepared by nucleophilic aromatic substitu-
tion of bromine in 4-bromo-5-nitrophthalodinitrile, and the corresponding phthalocyanines were synthesized.
The physicochemical properties of phthalocyanines depend on the substituent in the aryl moiety.
Phthalocyanines are widely used as organic dyes
and pigments [2], catalysts of redox reactions [3],
semiconductor materials [4], and gas sensors [5].
However, unsubstituted phthalocyanines are poorly
soluble, which restricts their use.
Syntheses of soluble octasubstituted phthalocya-
nines were reported in numerous papers [6 9]. As
a rule, compounds with identical substituents were
prepared. Data on solubility in organic solvents of
complexes with different peripheral substituents are
scarce [1, 10 13]. This may be due to difficult avail-
ability of the corresponding initial compounds, disub-
stituted phthalocyanines.
R = t-Bu (II), NO2 (III), COOH (IV).
We have reported previously on synthesis of 5-ni-
tro-4-phenoxyphthalodinitrile by nucleophilic aromat-
ic substitution of bromine in 4-bromo-5-nitrophthalo-
dinitrile [14] and on preparation from this compound
of metal phthalocyanines [12]. It was noted that bulky
peripheral phenyl substituents make the phthalocya-
nines readily soluble in organic solvents.
We showed previously that in 4-bromo-5-nitro-
phthalodinitrile I the halogen atom undergoes nucleo-
philic substitution first [1, 14 16]. This is due to the
presence in the o-position of a strong electron accep-
tor, nitro group, decreasing the electron density on the
carbon atom bound to bromine.
Attempts to prepare II IV by the procedure used
Proceeding with these studies, with the aim to
for preparing 5-nitro-4-phenoxyphthalodinitrile [14]
elucidate the effect of substituent in the phenyl rings
on the physicochemical properties of phthalocyanines,
we prepared a series of 5-nitro-4-(4-R-phenoxy)-
phthalodinitriles including 5-nitro-4-(4-tert-butylphen-
oxy)phthalodinitrile II, 5-nitro-4-(4-nitrophenoxy)-
phthalodinitrile III, and 5-nitro-4-(4-carboxyphenoxy)-
phthalodinitrile IV, and also the corresponding octa-
substituted phthalocyanines.
failed. We succeeded in preparing II IV by reaction
of I with p-substituted phenols in the presence of
triethylamine.
Compounds II IV, recrystallized from ethanol,
are yellow powders insoluble in water and soluble
in benzene, acetone, chloroform, ethanol, and DMF.
After preparing and identifying dinitriles II IV,
we synthesized from them the corresponding octasub-
stituted phthalocyanines. Metal complexes IIa IIc,
IIIa, IIIb, and IVa were prepared by fusion with the
corresponding metal acetates at 190 200 C for 1 h.
Phthalodinitriles II IV were prepared as follows:
1
For communication IV, see [1].
1070-3632/02/7202-0307$27.00 2002 MAIK Nauka/Interperiodica

308
BALAKIREV et al.
Metal-free tetra-5-nitrotetra-4-(4-tert-butylphenoxy)-
phthalocyanine IId was prepared by demetallation of
its magnesium complex IIc (reprecipitation from con-
centrated sulfuric acid).
R = t-Bu (II), NO2 (III), COOH (IV); M = Cu (IIa, IIIa), Co (IIb, IIIb, IVa), Mg (IIc), 2H (IId).
The choice of the purification procedure was gov-
erned by the specific features of the phthalocyanines.
Compounds IIa IId, which are soluble in chloroform,
were purified by column chromatography (silica gel
L 40/100, chloroform). Compounds IIIa and IIIb
were purified by reprecipitation from concentrated
sulfuric acid. Complex IVa, which is readily soluble
in aqueous alkaline solutions, was purified by dis-
solution in 5% aqueous NaOH, followed by precipita-
tion with aqueous HCl.
4-position decrease the solubility in chloroform and
benzene. Previously a similar trend was observed for
cobalt tetra-5-nitrotetra-4-(4-sulfophenoxy)phthalo-
cyanine [12].
The electronic absorption spectra of the complexes
are typical of phthalocyanines and contain two absorp-
tion bands at about 330 (Soret band) and 670 700 nm
(Q band) (see table and figure).
Substituents in the 4-position of the phenyl ring
affect the position of the long-wave band insignifi-
cantly. Four bulky electron-donating tert-butyl groups
cause a slight bathochromic shift of the Q band rela-
tive to tetra-5-nitrotetra-4-phenoxyphthalocyanines,
whereas electron-withdrawing substituents (NO2,
COOH) cause a weak hypsochromic shift (see table
and figure). Apparently, the hypsochromic shift is due
to a decrease in the electron-donor power of the phen-
It should be noted that the nature of the substituent
strongly affects the physicochemical properties of the
complexes. For example, bulky tert-butyl groups in-
crease the solubility of the complex, as compared to
tetra-5-nitrotetra-4-phenoxyphthalocyanines, in chlo-
roform, benzene, acetone, and DMF. On the contrary,
electron-withdrawing nitro and carboxy groups at the
Yields, position of the first absorption band in the electronic absorption spectra, and analytical data for tetra-5-nitrotetra-
4-(4-R-phenoxy)phthalocyanines
max, nm
Found, %
H
Calculated, %
Comp. Yield,
Formula
no.
%
H2SO4
DMF chloroform
C
N
C
H
N
IIa
IIb
IIc
IId
IIIa
IIIb
IVa
42
38
32
29
65
61
54
808
784
686
677
694
694
686
676
668
698
686
714
64.5
64.1
66.4
67.5
51.2
51.4
55.2
4.2
4.3
4.3
4.4
1.6
1.6
2.4
12.2
12.3
12.4
12.8
17.6
17.4
12.7
C72H60CuN12O12
C72H60CoN12O12
C72H60MgN12O12
C72H62N12O12
C56H24CuN16O20
C56H24CoN16O20
C60H28CuN12O20
64.1
64.3
66.1
67.2
51.5
51.7
55.6
4.5
4.5
4.6
4.8
1.8
1.9
2.2
12.5
12.5
12.8
13.1
17.2
17.2
13.0
789, 817
794
683, 714
772
774
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002

NUCLEOPHILIC SUBSTITUTION IN 4-BROMO-5-NITROPHTHALODINITRILE: V.
309
oxy group on introducing an electron-withdrawing
substituent.
The electronic spectra of IId in organic solvents
resemble those of tetra-5-nitrotetra-4-phenoxyphthalo-
cyanine, i.e., in DMF there is a single strong absorp-
tion band in the visible range, whereas in chloroform
a two-band pattern typical of metal-free phthalocya-
nines [17] is observed (see table and figure).
The spectra of IIIa, IIIb, and IVa in DMF are
somewhat broadened, which may be due to their ten-
dency to association.
As expected, in going from organic solvents to
concentrated sulfuric acid the long-wave absorption
band undergoes a significant bathochromic shift,
which is due to protonation of the porphyrazine ring
at the meso nitrogen atoms [18]; the effect of substitu-
ents on the position of the long-wave absorption band
is similar to that observed in organic solvents (see
table).
Electronic absorption spectra in chloroform: (1) tetra-5-
nitrotetra-4-(4-tert-butylphenoxy)phthalocyanine IId (c 1.3
5
10
M) and (2) cobalt tetra-5-nitrotetra-4-(4-tert-butyl-
5
phenoxy)phthalocyanine IIb (c 1.3 10 M).
chloroform, and DMF. Yield 56%, mp 182 185 C.
Found, %: C 51.1; H 1.6; N 17.5. C14H6N4O5. Cal-
culated, %: C 51.5; H 1.9; N 17.2.
EXPERIMENTAL
5-Nitro-4-(4-carboxyphenoxy)phthalodinitrile IV.
Yellow powder soluble in ethanol, acetone, benzene,
chloroform, and DMF. Yield 31%, mp 180 182 C.
Found, %: C 58.6; H 2.5; N 13.3. C15H7N3O5. Cal-
culated, %: C 58.3; H 2.2; N 13.0.
The electronic absorption spectra were taken on
a Specord M-40 spectrometer at room temperature in
the range 300 900 nm (solutions in DMF, CHCl3,
and concentrated H2SO4).
The melting points were determined with a Boetius
heating stage.
Tetra-5-nitrotetra-4-(4-R-phenoxy)phthalocya-
nines IIa IId, IIIa, IIIb, and IVa (general proce-
dure). A mixture of 0.62 mol of 5-nitro-4-(4-R-phen-
oxy)phthalodinitrile and 0.17 mmol of appropriate
metal acetate was thoroughly ground, heated in a
quartz ampule to 190 200 C, and kept at this tem-
perature for 1 h. The cake was washed with dilute
HCl until the filtrate became colorless and with water
to remove chloride ions, and then dried at 60 C.
4-Bromo-5-nitrophthalodinitrile I was prepared as
described in [19].
5-Nitro-4-(4-R-phenoxy)phthalodinitriles II IV
(general procedure). To 30 ml of DMF at 20 25 C
we added 3.6 mmol of dinitrile I and 5.4 ml of ap-
propriate phenol, and then 5.4 mmol of triethylamine.
The mixture was stirred for 6 h at room temperature.
After reaction completion, the mixture was poured
into 50 ml of a water ice mixture. The precipitate
was filtered off and washed with 5% alkali and water
until the wash water became neutral and colorless.
The completeness of removal of hydroxy compounds
was checked by the negative reaction with a diazo
compound. The reaction products were recrystallized
from ethanol.
Metal-free phthalocyanine IId was prepared by de-
metallation of IIc (reprecipitation from concentrated
sulfuric acid).
Compounds IIa IId were extracted with chloro-
form, and the solvent was evaporated at reduced pres-
sure. Refining was performed by column chromatog-
raphy (silica gel L 40/100, chloroform). Complexes
IIIa and IIIb were recrystallized from concentrated
sulfuric acid with subsequent extraction of impurities
with acetone. Compound IVa was purified by dissolu-
tion in 25 ml of 5% aqueous NaOH. The resulting
green solution was filtered, and the filtrate was acidi-
fied with HCl to weakly acidic reaction. The blue-
green precipitate was filtered off and washed with
distilled water to neutral reaction.
5-Nitro-4-(4-tert-butylphenoxy)phthalodinitrile II.
Yellow powder soluble in ethanol, acetone, benzene,
chloroform, and DMF. Yield 45%, mp 176 178 C.
Found, %: C 67.8; H 4.4; N 13.3. C18H15N3O3. Cal-
culated, %: C 67.3; H 4.7; N 13.1.
5-Nitro-4-(4-nitrophenoxy)phthalodinitrile III.
Yellow powder soluble in ethanol, acetone, benzene,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002

310
BALAKIREV et al.
9. Zhao, Y.I., Gan, L.B., Zhou, D.J., Jiang, J.Z., and
The analytical data, yields of the compounds, and
position of the Q band in the electronic absorption
spectra are listed in the table.
Liu, W., J. Solid State Commun., 1998, vol. 106,
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10. Mikhalenko, S.A., Surovtseva, A.P., and Luk’ya-
nets, E.A., Anilinokras. Prom st., 1976, issue 2,
pp. 1 7.
ACKNOWLEDGMENTS
The study was financially supported by the Minis-
try of Education of the Russian Federation, project
no. 97-0-9.4-381 in the field of basic natural science.
11. Mikhalenko, S.A. and Luk’yanets, E.A., Anilinokras.
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