Low-temperature synthesis of phthalocyanine and its metal complexes

Article abstract of DOI:10.1134/S1070328406090016

Conditions for synthesizing unsubstituted phthalocyanine and its metal complexes from phthalonitrile at low temperatures (0-50°C) are optimized. Phthalocyanine and phthalocyaninates are produced under these conditions using activated Rieke metals, metals on inert substrate, sources of soluble metals in the form of unstable metal complexes, zeolites, solid-phase electrosynthesis of phthalonitrile, and UV irradiation. The use of pyrophoric metals is found to be the most efficient due to a large number of defects in their structure favoring the initial stage of phthalonitrile cyclization on a metal matrix. The suggested mechanism of formation of phthalocyanine macrocycle assumes participation of metal agglomerates occurring in activated metals. Pleiades Publishing, Inc., 2006.

Full text of DOI:10.1134/S1070328406090016

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2006, Vol. 32, No. 9, pp. 617–631. © Pleiades Publishing, Inc., 2006.
Original Russian Text © B.I. Kharisov, U. Ortiz Mendez, J. Rivera de la Rosa, 2006, published in Koordinatsionnaya Khimiya, 2006, Vol. 32, No. 9, pp. 643–658.
Low-Temperature Synthesis of Phthalocyanine
and Its Metal Complexes
B. I. Kharisova, b, U. Ortiz Mendezb, and J. Rivera de la Rosab
a Institute of Physical Chemistry, Russian Academy of Sciences, Leninskii pr., 31 Moscow, 119991 Russia
b Universidad Autonoma de Nuevo Leon, Monterrey, Mexico
Received November 18, 2005
Abstract—Conditions for synthesizing unsubstituted phthalocyanine and its metal complexes from phthaloni-
trile at low temperatures (0–50°ë) are optimized. Phthalocyanine and phthalocyaninates are produced under
these conditions using activated Rieke metals, metals on inert substrate, sources of “soluble” metals in the form
of unstable metal complexes, zeolites, solid-phase electrosynthesis of phthalonitrile, and UV irradiation. The
use of pyrophoric metals is found to be the most efficient due to a large number of defects in their structure
favoring the initial stage of phthalonitrile cyclization on a metal matrix. The suggested mechanism of formation
of phthalocyanine macrocycle assumes participation of metal agglomerates occurring in activated metals.
DOI: 10.1134/S1070328406090016
The classical unsubstituted phthalocyanine (H2Pc) lonitrile [7–10]. Phthalocyanine gives stable metal
and its metal complexes (MPc) have been intensively
studied since 1930 [1–4] and are widely used today in
dye industry. Phthalocyanines can be prepared by tra-
ditional reactions from different precursors in non-
aqueous solvents with high boiling points and in the
presence of activators, catalysts and/or promoters at
80–250°ë [5, 6].
complexes with Fe, Cu, or Ni and low-stable complexes
with Mg or Sb (as regards the possibility of metal
“extraction” from a complex without destruction of the
phthalocyanine structure). In both chemical and elec-
trochemical methods, phthalocyanine complexes can
be produced from free metals and their salts.
Metal phthalocyaninates (MPc) are obtained
obtained also by electrochemical methods from phtha- according to the following reactions:
Phthalocyanine and its metal complexes can be
CN
M, 300°C
NH2
O
O
MX2, (NH2)2CO
N
N
N
O
170–220°C
N
M
N
N
O
CN
N
M
N
150–280°C
CN
NH2
MX2
NH
70–120°C
NH2
617

618
KHARISOV et al.
The main precursors of phthalocyanine and its metal complexes are
NH
NH
CN
CN
CONH2
CONH2
CONH2
o-Cyanobenzamide
O
CN
NH
Phthalonitrile
Phthalamide
1,3-Diiminoisoindoline
O
O
COOH
COOH
NH
O
O
Phthalic anhydride
Phthalimide
Phthalic acid
The phthalonitrile cyclization can be realized using the following activators:
CH3
H3C
CH3
C(CH3)3
N
N
P
N
N
N
N
N
CH3
BEMP
N
N
N
N
DBU
DBN
TBD
N
N
+ EtOH
N
N
+
DBU
H
where DBU is 1,8-diazabicyclo[5.4.0]undec-7-ene, metals, i.e., active (calcium), chemically inactive (iron)
DBN is diazabicyclo[4.3.0]-non-5-ene, TBD is
1,5,7-triazabicyclo[4.40]dec-5-ene, BEMP is 2-t-bu-
tylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-
diazaphosphorine.
Of the known phthalocyanine precursors, phthaloni-
trile and 1,3-diiminoisoindoline (1,3-D), which is also
an intermediate product of phthalonitrile or urea con-
densation with phthalic anhydride, are the most stud-
ied, since the preparation of a free H2Pc from these
[11] and activated (activated magnesium) [12] metals,
solid substrates [13], zeolites [14], and UV irradiation
of the reaction mixture [15]. The classical and nontra-
ditional or little-known methods (for example, micro-
wave, UV, laser irradiation or ultrasound exposure, the
use of free radicals, metals, strong organic bases or
reactions on activated surfaces, as well as electrosyn-
thesis and nuclear reactions) of preparation of phthalo-
cyanines and its metal complexes (mainly, the synthesis
compounds is the most simple reproducible process. of unsubstituted phthalocyanine at low temperatures)
However, these precursors are used only in experimen-
tal studies because of their high cost, as compared to
that of urea and phthalic anhydride applied in dye
industry in the production of H2Pc or its metal com-
plexes (usually CuPc).
were reported in [16]. Since the low-temperature syn-
theses of phthalocyanines are poorly studied, it was of
interest to develop the procedures for preparing phtha-
locyanines and their metal complexes from precursors
at temperatures close to room temperature using metals
with different degrees of activation. In this work, we
used activated Rieke metals [17], metals on an inert
substrate, low-stable Mg complexes, zeolites, UV irra-
diation of a reaction mixture, and solid-phase elec-
A few methods of preparation of phthalocyanines at
low temperatures (below 50°C) have been reported in
the literature without systematic study of these pro-
cesses. In addition to electrochemical methods, one
should mention several methods with the use of some trosynthesis of phthalonitrile.
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LOW-TEMPERATURE SYNTHESIS OF PHTHALOCYANINE
619
Table 1. Elemental analysis data for H2P and its metal com-
Synthesis of Rieke metals. Activated metals (Rieke
metals: Ni, Cu, Zn, and Mg) were prepared in a dry
chamber (ê4O10) in the atmosphere of dry nitrogen. In
the case of Ni, anhydrous NiCl2 (17 g, 0.13 mol), dried
at 130°ë before use, small pieces of metallic potassium
(9.8 g, 0.25 mol), and THF (350 ml), freshly distilled
over metallic sodium, were placed in a 500-ml flask
plexes
Content (found/calcd.), wt %
Com-
pound
C
H
N
M
H2Pc 74.31/74.79 3.12/3.51 21.27/21.70
with a condenser (all the procedures were performed in CuPc 66.09/66.65 1.98/2.78 18.85/19.44 10.71/11.03
a dry chamber), and gradually heated to THF boiling
point (66°ë) for 12 h with intensive stirring. The sus-
pension was stored for 3–5 h without stirring and heat-
ing until precipitation of the obtained metal. Then, THF
NiPc
MgPc 70.97/71.53 2.05/2.98 20.17/20.86 4.08/4.52
PbPc 52.84/53.35 1.54/2.22 14.89/15.56 28.35/28.78
66.78/67.22 2.01/2.80 19.15/19.60 9.87/10.27
was decanted and a new portion of a fresh THF was ZnPc 65.89/66.44 2.08/2.77 18.85/19.37 10.86/11.31
added (250–300 ml), and the mixture was stirred for
5 min and stored for 1 h. This procedure was repeated
twice. The same sequence of procedures was used to
prepare the other activated metals. Since the activity of
freshly prepared Rieke metals decreases within several
hours due to agglomeration of small particles, the metal
was used immediately or not later than 2 days after
preparation and was stored under THF layer. In addi-
tion to a standard procedure of preparation of Rieke
metals in a dry chamber, we used multipurpose setup of
our own design for synthesizing activated metals.
CdPc 60.89/61.44 1.71/2.56 17.08/17.92 17.12/17.98
Synthesis of phthalocyaninates from Rieke met-
als. To obtain metal phthalocyaninates at low tempera-
tures, Rieke metal (0.2–0.5 g on conversion to a pure
metal) was added to 20 ml of a solution containing
phthalonitrile (3.5 g) and 25% CH3ONa (0.5 ml) in
methyl alcohol (in some cases, CH3ONa was not used).
The approximate ratio of metal : phthalonitrile = 1 : 4
was used (in order to establish the optimum synthesis
conditions, the 1 : 8 ratio was also used). The flask was
placed in ultrasonic bath and kept for 12–72 h at 0–
50°ë. After termination of the reaction and cooling of
the reaction mixture to room temperature, the obtained
dark violet product was separated from unreacted metal
by shaking (using the difference in their densities) and
decanting with a solvent. Some amount of the reaction
product was scraped off from the flask walls. The prod-
uct was washed with a hot ethanol and dried in air.
Synthesis of metal phthalocyaninates with the
use of nonactivated metals and nickel in different
forms (standard and activated, except for Rieke
nickel). A series of zero-valent metals (Cu, Ni, Cd, Zn,
Fe, Sn, and Mg) was used. Copper was used as a pow-
der or plates, while nickel was used in three forms. i.e.,
as plates, Raney and pyrophoric nickel, which was
stored under water layer. In the case of a standard pro-
cedure, a metal (0.25 g) was placed in an alcoholic
(C1−C8) solution (10–20 ml), containing equimolar
amount of phthalonitrile and 5 drops of 30% CH3ONa
in methanol. The flask was placed in ultrasonic bath and
kept for 24–72 h at 0–50°C. Phthalocyaninate obtained
was separated from unreacted metal by using the differ-
ence in the densities of phthalocyaninate and a metal,
i.e., by shaking the reaction flask and by washing with
ethanol in Sohxlet apparatus and drying in air. Some
experiments were carried out without ultrasonic treat-
ment, in particular, when pyrophoric nickel was used.
In this case, the amount of nickel required for the reac-
tion was determined roughly, since it was impossible to
separate it from water. The solvents used in experi-
ments were ethylene glycol, methanol, ethanol, isopro-
panol, 1-butanol, isobutanol, tert-butanol, 1-octanol,
2-ethoxyethanol, acetonitrile, etc.
Synthesis of metal phthalocyaninates from Mg
and Zn in different forms. Magnesium was used in
three forms, namely, as metal shavings preliminarily
treated before use as described below, Rieke magne-
sium, and as classical complexes of “soluble magne-
sium”–Mg(anthracene) · 3THF and an adduct of mag-
nesium and butadiene C4H6Mg · 2THF (1 : 1). Zinc was
used only as Rieke metal, since the preliminary experi-
ments with nonactivated zinc at low temperatures
revealed only the trace amounts of zinc phthalocyani-
nate.
To clean the magnesium surface, its shavings (20 g)
were cut in small pieces and placed in a 500-ml flask
with 4M NH4Cl solution (100 ml). The mixture was
heated to 40°ë for 30 min (pH 4–8), avoiding the for-
mation of magnesium hydroxide. The solution was
decanted, and the metal was washed twice with distilled
water (with 50-ml portions), three times with absolute
alcohol (with 50-ml portions), and twice with THF
(with 50-ml portions); it was kept under THF layer.
The chemical analysis and physicochemical study
of phthalocyanine and its metal complexes were per-
formed using standard procedures (Table 1). According
to the chemical analysis data, the composition of the
products obtained corresponded to typical metal phtha-
Rieke magnesium was obtained from anhydrous
locyaninates MPc (93–97%). In some experiments, MgCl2 following the procedure used in the case of
slight deviations were observed in the composition of nickel. The complex Mg(anthracene) · 3THF was pre-
the obtained compounds (up to 1%), which is accept- pared in a dry chamber in the atmosphere of dry nitro-
able in the chemistry of phthalocyanines.
gen in the following way. Magnesium (24.3 g, 1 mol),
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 9 2006

620
KHARISOV et al.
which was cleaned and cut beforehand, was placed in a
The solutions of the corresponding phthalocyanine
three-neck flask (2 l) and anthracene (200 g) was added. precursors were irradiated for 3 h in photochemical
The mixture was heated for 10 min at 110°ë in a drier.
A condenser was connected to the flask and the latter
was filled with nitrogen. Then, 1 l of dried THF and
several drops of ethyl bromide (~0.05 ml) were added.
The mixture was stirred for 36 h at 60°ë in ultrasonic
field. The resulting orange precipitate was mechani-
cally separated in a dry chamber from pieces of unre-
acted metal, washed twice with THF (with 150-ml por-
tions), and dried in vacuum for 2 h. The product was
obtained in 64% yield and contained traces of
anthracene and magnesium. The synthesis of the indi-
cated compound is poorly reproducible. The same pro-
cedures were used to obtain Mg complex with butadi-
ene. Rieke magnesium and zinc and the synthesized Mg
complexes with anthracene and butadiene were intro-
duced in the reaction with phthalonitrile in the same
way as in the case of copper and nickel.
reactor (mercuary lamp, 1200 W). Methanol, ethanol,
isobutanol, tert-butanol, cyclohexanol, 2-octanol, eth-
ylene glycol, ethoxyethanol, DME, trichlorobenzene,
nitrobenzene, DMSO or DMF were used as solvents.
Each sample contained 0.5–2 g of precursor (depending
on its solubility in the solvent used), 5–10 ml of a sol-
vent, and 2 drops of activator (in the case of phthaloni-
trile). The compounds formed were purified and identi-
fied by standard methods.
Synthesis of phthalocyanine with the use of
zeolites. The starting reagents were phthalonitrile,
30% solution of CH3ONa in CH3OH and a solvent
(methanol, ethanol, benzene, 1-propanol, 1-pentanol,
2-butanol, THF, ethoxyethanol, and DME). Also, zeo-
lite (in two forms, i.e., “green” and “blue,” with the sur-
face area 38.4 and 29.6 m2/g, respectively) was used.
Both forms were characterized by X-ray powder dif-
fraction, atomic absorption, and surface area studies.
The nitrogen adsorption isotherms were obtained at
77 K after the sample degassing in vacuum (below
0.1 mm Hg) at 200°C for 8 h. The β-adsorption model
was used for interpretation of the nitrogen adsorption
isotherms. The samples of zeolites before and after
interaction with phthalonitrile were studied by scan-
ning electron microscopy.
Synthesis of metal phthalocyaninates using met-
als on inert substrate. Copper and nickel on the alu-
minium oxide substrate were prepared as follows. A
powdered Al2O3 (50 g) was mixed with 200 ml of 20%
aqueous solution of the corresponding metal salt
(CuSO4 · 5H2O or NiCl2) and the mixture was stirred
for 10 min. Then, several ml of 10% ammonia solution
was added to convert the salts to hydroxides and the
mixture was stirred again for another 10 min. The com-
pound obtained was filtered off, heated at 300°ë in a
muffle furnace for 5 h in order to decompose hydrox-
ides, and was reduced with hydrogen at 350°ë for 4 h.
The obtained powder of å–Al2O3 was kept in a closed
vessel in the atmosphere of nitrogen.
In the standard method, a powdered zeolite (1 g) was
added to nonaqueous solvent (10 ml), containing phth-
alonitrile (1 g) and 5 drops of 30% solution of CH3ONa
in methanol. The mixture was placed in ultrasonic bath
and kept there for 24–72 h at 0–40°C. Some experi-
ments were conducted without ultrasonic treatment.
After termination of the reaction, the obtained blue
compound was separated from zeolite by shaking
(using the difference in the densities of zeolite with
phthalocyanine inside and phthalocyanine without car-
rier) and decantation for 2–4 times. This process was
performed with difficulty, since both phases (zeolite
and phthalocyanine) are solids and cannot be separated
fully by the indicated method. Therefore, the yields of
the obtained compounds were estimated with account
of the possible admixture of zeolite (2–5%). Phthalocy-
anine for analysis was obtained after performing
repeated (5–7 times) procedures of separation from
zeolite. Phthalocyanine formed was washed with hot
ethanol in the Sohxlet apparatus and dried in air.
To prepare metal phthalocyaninates at low tempera-
tures, a powdered å–Al2O3 (3–5 g) was added to a mix-
ture of 20 ml of phthalonitrile solution (3–5 g) and
5 drops of 30% CH3ONa solution in methanol. The
flask was placed in ultrasonic bath and was kept there
at 0–50°ë for 24–72 h. Then, the amount of the
obtained compound required for analyzing was sepa-
rated from aluminium oxide using the difference in the
densities of Al2O3 and metal phthalocyaninates,
washed with ethanol, and dried in air. Because of the
difficulty in separation of aluminium oxide and metal
phthalocyaninate, the practical yield of the latter com-
pound was calculated from the difference in the weight
of a dried product. Some experiments were conducted
without ultrasonic treatment. The results of elemental
analysis and IR spectroscopy confirm the formation of
copper and nickel phthalocyaninates.
According to the elemental analysis data, the com-
positions of the compounds obtained corresponded to
free phthalocyanine H2Pc. The deviations in the data of
elemental analysis were 0.05–0.30%. The reaction
products were analyzed by the atomic adsorption
method for the metal ions, which could appear from
zeolite; the amount of the “external” metal ions was
Synthesis of phthalocyanine at low temperatures
using UV irradiation of solutions of its precursors in
nonaqueous solvents. The effect of UV irradiation of
nonaqueous systems containing phthalonitrile (at 0–
60°C) or 1,3-D (up to 100°C) was studied. Sodium
methylate (or DBU) was used as activator, although negligible (0–0.3%). The composition of zeolites is
some parallel experiments were performed without this given in Table 2, their diffraction patterns are shown in
reagent.
Fig. 1.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 9 2006

LOW-TEMPERATURE SYNTHESIS OF PHTHALOCYANINE
621
Table 2. Composition of zeolites used in the synthesis of
Synthesis of free phthalocyanine and Cu phtha-
locyaninate by direct solid-phase electrochemical
method. Electrosynthesis was performed with the use
of standard Pt or Cu anode (2 × 2 cm) and Pt gauze cath-
ode with a large surface area (~30 cm2). The solvent
used in the synthesis was N,N-dimethylethanolamine
(DME), which favors the formation of phthalocyanine
at lowered temperatures [18]. Phthalonitrile (16 g),
DMA (7–10 ml), tetrabutylammonium perchlorate
(0.02 g), and 3 drops of 25% solution of CH3ONa in
methanol were placed in 200-ml cell. The major portion
of phthalonitrile was present as a solid phase, and the
cathode was completely immersed in this phase. The
electrolysis was conducted at 10–20 mA, 20–30 V for
2 h with an accurate temperature control (0–20°ë). On
termination of the process, phthalocyanine obtained
was purified in the Sohxlet apparatus. The yield of
phthalocyanine or CuPc on phthalonitrile was 5–30%
(depending on the process temperature).
phthalocyanine
Content, wt %
Composition
“green” zeolite
“blue” zeolite
SiO2
76.20
8.39
0.33
6.94
2.25
0.10
1.75
0.10
0.56
<0.05
85.68
8.15
1.95
1.00
1.31
0.02
0.30
0.02
0.57
<0.05
Al2O3
Na2O
CaO
K2O
MgO
Fe2O3
MnO2
TiO2
P2O5
The data of elemental analysis of phthalocyanine
and transition metal phthalocyaninates obtained at rel-
atively low temperatures are presented in Table 1. The
elemental analysis for a metal was performed by atomic
adsorption method, while C, H, and N were analyzed
on a CHONS (Perkin-Elmer) microanalyzer. IR spectra
were recorded on Perkin-Elmer instrument at 4000–
400 cm–1 (with KBr pellets). IR spectra correspond to
those of phthalocyaninates obtained by traditional
methods. IR spectrum of CuPc is given as an example
(ν, cm–1): 3500–3380 vs, br, 2815 m, 2504 m {ν(C–H)};
phthalocyanine destruction products); 1607 s, 1524 m
{ν(C–C)ar}; 1448 m {ν(C–C)pyr}; 1385 vs, 1365 s (pyr-
role N–Cα); 1320 m, 1150 s {ν(C–N)}. Some absorp-
tion bands (at 2865 and 2705 cm–1) are absent from the
spectrum of free H2Pc, which however exhibits addi-
tional bands at 622, 675, 690, 720, 1309, and 1500 cm–
1. IR spectra of H2Pc or CuPc obtained in different syn-
theses are almost identical and only differ in the band
intensities. The electronic absorption spectrum of CuPc
in Py (λ, nm): 692–693, 659–660 (Q-band), 640, 602–
2300–2280 s, 1730 vs (probably, corresponds to the 604. X-ray powder diffraction analysis of zeolite sam-
I
1200
1000
‡
800
600
400
200
0
¥
¥
¥
b
60
50 55
2θ, deg
5
10 15
20 25 30
35 40
45
Fig. 1. X-ray pictures of zeolites: (a) “green” and (b) “blue.” Phases: (ꢀ) clinoptilolite, (ꢁ) SiO , and (×) CaCO .
2
3
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 9 2006

622
KHARISOV et al.
ples was performed on Siemens diffractometer (CuKα turned most active in the process of phthalonitrile
radiation). A DSV950 scanning electron microscope cyclization (Table 3). Unlike the other metals, Ni does
(Carl Zeiss) was used to study zeolite samples.
not require the addition of CH3ONa to the reaction mix-
ture (although the latter reagent increases the product
yield). In addition, the formation of NiPc was observed
not only in alcohols, but also in THF, which did not
occur in the case of the other metals. Small amount of
water did not influence the phthalonitrile cyclization
process; in blank experiments without pyrophoric
nickel in the presence of almost the same amounts of
water, no NiPc was formed.
RESULTS AND DISCUSSION
The authors of [11] suggested very mild conditions
for preparing phthalocyaninates at room temperature
with the use of a series of primary alcohols and metals
that had different natural activity but were not chemi-
cally activated. We used more extended series of metals
in activated pyrophoric form.
We believe that the high density of surface defects of
pyrophoric nickel provides its highest activity in the
process of phtahlonitrile cyclization. It is surprising
that another form of Ni, i.e., “dry” Raney nickel, did not
show noticeable activity, while the plate of common
electrolytic nickel turned even more active than a pow-
der of Raney nickel, which is likely to be explained by
the oxidation processes occurring on its surface and
thus reducing the initial activity of a metal. The parti-
cles of activated nickel (pyrophoric and Rieke nickel,
100 nm) are smaller than the particles of “dry” Raney
nickel (20–40 µm) and have higher surface energies,
which makes the process of phthalonitrile cyclization
easier and thus requires lower initial temperatures of
the process. Obviously, it is the high concentration of
surface defects of activated metals and small sizes of
metal aggregates that make them very active both in the
process of phthalonitrile cyclization and in the other
organic and organometallic reactions. Thus, the yield of
NiPc in the reaction with participation of Raney nickel
in methanol and ethanol (T = 25°ë) was 30–35%, while
in the case of pyrophoric form of a metal (with admix-
ture of water), it was 38, 65, 94, 70, 78, and 30%,
respectively, in 1-propanol, 2-propanol, isobutanol,
tert-butanol, 1-octanol, and ethylene glycol. Reproduc-
ible semiquantitative yields were achieved in the sys-
tems Cu–methanol, Cu–ethanol, Zn–methanol, Zn–1-
octanol, and Mg–methanol at 50°C. In a solution of
phthalonitrile in acetonitrile at 25–50°C, cadmium and
lead gave from 28 to 65% of the products, but the
results were reproducible to a lesser extent. The most
reproducible results for Ni, Cu, Zn, Mg, Cd, and Pb are
given in Table 3.
In the synthesis of metal phthalocyaninates from
different precursors in nonaqueous solvents at temper-
atures above 100°C, the metal form is of no importance,
though its finely divided powder dissolves more rapidly
than the metal wire or plate. At low temperatures (0–
50°C), when the rates of a metal dissolution and of
phthalonitrile cyclization (if it is used) sharply
decrease, either additional “impetus” can produce pos-
itive effect on the process of macrocycle formation.
Thus, surface defects of strong organic bases (solid
CH3ONa) [13] of metals [11, 12] can serve as impetus
for attaining the energetic state, such that the initial
temperature of phthalonitrile cyclization can be low-
ered.
It was found that the efficient sources of defects are
activated metals (in particular, Rieke metals) at temper-
atures 0–50°ë [19]. These metals are peculiar in very
high concentration of surface defects as compared to
that of nonactivated metals. These properties are
responsible for their wide application in organic and
organometallic syntheses. Moreover, the activity of
such metals can be increased using the additional ultra-
sonic treatment of the reaction mixture.
The data on the use of Rieke metals with phthalocy-
aninate precursors are almost absent in the literature,
except for the reported activated magnesium. In addi-
tion to traditional use of Mg in nonactivated form in the
synthesis of Grignard reagents, it is applied also in acti-
vated forms (for example, as activated magnesium
(Mg*), “soluble” zero-valent metal produced from the
classic complex Mg(anthracene)3 · 3THF and ågH2*
[20]) in different organometallic syntheses. Sometimes,
its preliminary activation is required [21] using differ-
ent methods (mechanical or ultrasonic treatment or
though the formation of intermediate active Mg com-
plexes). The reaction of nonactivated Mg with phtha-
lonitrile at 295°ë (boiling point of phthalonitrile) with
9.5% yield was reported for the first time in [22]. Acti-
vated magnesium Mg* was used in a boiling solution of
phthalonitrile in 1,2-dimethoxyethane (5 min, the yield
of MgPc 38%) [12]. In recent years, Mg phthalocyani-
nate did not attract the researchers’attention, except for
the works by Mizuguchi devoted to its crystal structure
and π–π-interactions [23, 24].
When phthalonitrile cyclization was performed with
the use of Rieke nickel (specific surface are 32.7 m2 g−1)
[25], prepared from anhydrous nickel chloride and
metallic potassium, the yields of nickel phthalocyani-
nate in different solvents did not differ significantly
from those obtained with the use of pyrophoric nickel
(Aldrich) (Table 3) and were always greater in metha-
nol and ethanol, as in the above-mentioned experi-
ments. It was found that the reduction in a molar ratio
of metal : phthalonitrile from 1 : 4 to 1 : 8 resulted in a
noticeable decrease in the yields from almost quantita-
tive yields to <45%. With excess activated metal, the
yield increases due to a substantial increase in the num-
Of the three nickel forms used in this work (plate, ber of the reaction matrices (surface defects of a metal).
Raney nickel and pyrophoric nickel), the latter form It was also noted that in some cases, activated metal
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 9 2006

LOW-TEMPERATURE SYNTHESIS OF PHTHALOCYANINE
623
Table 3. The yields of metal phthalocyaninates obtained from metals in different forms and phthalonitrile as precursor (treat-
ment for 12 h, molar ratio metal : phthalonitrile = 1 : 4 or 1 : 8)
The yield of MPc,
wt %
The yield of MPc,
wt %
Medium
T, °C
Medium
T, °C
Ni (Raney) (1 : 4)*
Ethanol, CH3ONa
0
10
20
35
50
15
22
25
25–32
35
Methanol, CH3ONa
25
30
40
50
25
35
45
45–55
50–55
30
Ethanol, CH3ONa
1-Propanol
20
35
50
20
35
50
0
10
20
35
50
0
4
14
26
5
16
25–30
<3
<5
8–12
14
27
8
13
17–20
20–25
25–30
30
40
50
38
45–50
45–55
1-Propanol, CH3ONa
1-Butanol
Ni (pyrophoric, under water layer) (1 : 4)
Methanol, CH3ONa
0
10
25
0
10
25
0
10
25
0
7
14
100
<4
5–9
80–90
25
25
100
<2
10
70–75
38
Methanol
Ethanol, CH3ONa
Ethanol
1-Butanol, CH3ONa
10
20
35
50
10
25
25
25
25
25
25
25
Cu (powder) (1 : 4)**
1-Propanol, CH3ONa
2-Propanol, CH3ONa
Isopropanol, CH3ONa
Tert-butanol, CH3ONa
1-Octanol, CH3ONa
Methanol, CH3ONa
Methanol, CH3ONa
Nonactivated Zn (1 : 4)
Methanol, CH3ONa
25
25
60–65
55–60
65
94
70
78
25
30
40
50
25
30
40
50
25
30–35
30–40
35–40
20
25–35
30–41
35–40
Ethylene glycol, CH3ONa
~30 (isolated fraction
of a product; the real
reaction yield
Octanol, CH3ONa
is higher)
THF
25
25–30
Ni (plate) (1 : 4)*,**
Methanol, CH3ONa
Ethanol, CH3ONa
25
25
80–85
75–85
Nonactivated Zn (1 : 8)
Methanol (ethanol, pro-
panol, butanol), CH3ONa
20–50
5–20
Ni (Rieke) (1 : 8)***
Methanol
0
10
20
35
50
0
10
20
35
50
0
<3
<3
17
18
45
11
16
20
22–26
25–30
<4
8
11
Zn (Rieke) (1 : 8)
Methanol (ethanol, pro-
20
20, 35
50
10–15
15–20
39
panol, butanol), CH3ONa
Methanol (ethanol, pro-
panol), CH3ONa
Methanol, CH3ONa
Ethanol
1-Butanol, CH3ONa
Purified nonactivated Mg (1 : 4)
Methanol, CH3ONa
25
30
40
50
30
30–35
45–50
70–72
100
10
20
35
50
1-Propanol, CH3ONa
40
Purified nonactivated Mg (1 : 8)
17
31
Methanol, CH3ONa
20
35
50
11–17
15–20
18–22
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624
KHARISOV et al.
Table 3. (Contd.)
The yield of MPc,
The yield of MPc,
wt %
Medium
T, °C
Medium
T, °C
wt %
Ethanol (1-propanol, 1-bu- 20–50
tanol), CH3ONa
0–15
Complexes Mg(anthracene) · 3THF and Mg(butadiene) · 2THF
(poorly reproducible)
Mg (Rieke) (1 : 8)****
Methanol (ethanol, pro-
panol, butanol) CH3ONa
20–50
5–10
Methanol, CH3ONa
20
35
50
5
20
33
Cd*****
Ethanol, CH3ONa
20
35
50
20
35
50
20
35
50
7
36
27
21
43
57
36
66
85
CH3CN, CH3ONa
25
30
40
50
32
40
55
62
1-Propanol, CH3ONa
1-Butanol, CH3ONa
Pb (plate)*****
CH3CN, CH3ONa
25
30
40
50
28
35
57
65
* In the other solvents used (1- or 2-propanol, all butanol isomers, 1-octanol, ethylene glycol, acetonitrile, benzene, xylene, THF and
DMF), the formation of metal phthalocyaninates was not observed. At a ratio of metal : phthalonitrile = 1 : 8, the yields are less
than 15%.
** At a higher temperature, the yields are practically quantitative.
*** At a ratio of metal : phthalonitrile = 1 : 8. At a ratio of 1 : 4, the yields are close to those obtained with the use of pyrophoric nickel
under water layer. In the other solvents (isopropanol, isobutanol, tert-butanol, 1-octanol, 2-ethoxyethanol), phthalocyanines were
obtained in trace amounts.
**** At a ratio of metal : phthalonitrile = 1 : 4, the yields varied within 70–100%.
***** No phthalocyaninates were formed in alcohols.
was not completely spent in the reaction, even after and discussed in the literature (except for CuPc). More
72-h ultrasonic exposure with excess phthalonitrile. In than 30 years ago, the authors of [26] considered the
the case of Rieke copper, the yields of copper phthalo- mechanism of NiPc formation from nickel salts, urea,
cyaninate did not differ essentially from those obtained and phthalic anhydride as precursors. General concepts
in the experiments with nickel.
of the mechanism of interaction of a metal surface and
organic substrate in ultrasonic field were discussed in
[27]. This mechanism involves participation of defects
and preferable reaction centers on a metal surface with
subsequent “extraction” of the metal atom “associated”
with organic partner. The same mechanism is likely to
underlie the process with participation of the metals on
an inert substrate, when the metal atoms are supplied by
the metal aggregate on the inner surface of Al2O3 or of
the other inert substrates, for instance, TiO2.
The use of different forms of metallic magnesium,
its complexes with anthracene and butadiene and of
zinc (Table 3) favors phthalonitrile cyclization at rela-
tively low temperatures. The yield of the corresponding
phthalocyaninates is greatly determined by the nature
of the solvents used, the highest yields being obtained
with alcohols having low molecular mass. An increase
in the temperature increases the yield of phthalocyani-
nates. The activity of “soluble” magnesium in the form
of anthracene or butadiene complexes with respect to
phthalonitrile turned lower than the expected value.
It is known [28] that metals on the inert substrates
(TiO2, Al2O3, graphite, etc.) are used in organic and
organometallic syntheses as sources of a free metal
with increased activity. In this case, due to the metal
“dilution” with the inert matrix, the activity of metals
on the inert substrate is lower than that of highly active
Rieke metals, but higher than that of the metals in stan-
dard form (powder or plate).
We proposed the mechanism of these processes,
using nickel as an example, with participation of small
aggregates (hundreds of atoms) of activated metals ån
in the presence of CH3ONa (Fig. 2). The ån aggregate
has a large number of defects and forms preferable
reaction centers in ultrasonic field. Also, it serves the
source of free metal atoms, which react with organic
We proposed copper, nickel and other transition
substrate. In strong ultrasonic fields, such aggregates metals on the inert Al2O3 substrate. The results
can be removed completely from the main surface of a obtained are listed in Table 4. As compared to Rieke
metal and can act as centers of cyclization of phthaloni- metals, constituting 70–100% of the reacting solid
trile molecules. Note that the mechanisms of formation phase, the experiments with the use of the metal–Al2O3
of metal phthalocyaninates were not adequately studied system were complicated by some difficulties, such as
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 9 2006

LOW-TEMPERATURE SYNTHESIS OF PHTHALOCYANINE
625
CN
CN
Ni + ROH
act.
Ni
The formation of preferable reaction centers‚
+
Detachment
of the Ni atom
Nucl–
Ni(OR)2
Nin–m
The formation of defects
in ultrasonic field
Nin
Nucleophilic attack at one
of phthalonitrile cyano group
Destruction of
Ni aggregate
Nucl– = CH3O–
1. In the absence of Na methylate, the alcohol O atom.
2. Can participate in nucleophilic attack.
3. As a neutral nucleophile
R
O
H
N
Nucl
N
N
N
Ni
Nucl
–N
N
N
N
N
N
N
N
Ni
N
N
N
N
Coordinated
nucleophile
The Ni atom is oxidized
to ions and releases 2e
for bond formation
N
N
N
Nucl
N
N
Ni
N
Nucl
N
N
N
N
Nucl
N
N
N
N
N–
N–
2e
N
N
Ni
Nucl–
Ni
+
N
N
N
Regenerated
nucleophile
N
N
N
Fig. 2. The mechanism proposed for the reaction of phthalonitrile cyclization on matrices of activated metals in different forms.
separation of two solid phases, namely, metal phthalo- applied. On the other hand, when metals on the inert
cyaninate formed and Äl2é3. The same difficulty arose substrate were used, the densities of Äl2é3 and of metal
in the case of incomplete dissolution of pyrophoric phthalocyaninates differed insignificantly and there-
metals, but their density, for example, of nickel, was fore, only a small portion of relatively pure phthalocy-
considerably higher than the density of a bulky MPc aninate could be separated from the inert substrate,
precipitate, which was accumulated at the top of the purified and analyzed. In this connection, the yield of a
tubes or flasks, if no stirring or ultrasonic treatment was final product in the majority of experiments was deter-
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626
KHARISOV et al.
Table 4. The yields of Cu and Ni phthalocyaninates
obtained with the use of metals on an inert substrate
(M−Al2O3) in the presence of CH3ONa
In the case of copper, X-ray pattern of a metal–
Al2O3 mixture shows the aluminium oxide phase and
free copper, while in the case of nickel, the phase of alu-
minium oxide, small admixture of AlO(OH) formed
during short-time treatment with a solution of NH3 ·
H2O (or sometime, with NaOH), bunsenite NiO
(formed, obviously, due to incomplete reduction of
NiO), and metallic nickel.
Solvent
T, °C
The yield of MPc, wt %
Cu–Al2O3
Methanol
23
35
20–35
25–35
30–42
22–35
27–35
25–40
25–30
35–45
38–45
20–31
37–45
40–45
Like with Rieke metals, a higher surface energy of
structural defects of metal aggregates favors more easy
cyclization of phthalonitrile penetrating into the bulk of
the inert substrate and coming in contact with metal
aggregates at the sites of their structural defects. There-
fore, we suggested the mechanism involving a series of
subsequent reactions of formation of phthalocyanine
cycle similar to that described above for Rieke metals
(Fig. 2). When a strong ultrasonic field is used, metal
aggregates can be fully removed from cavities in Äl2O3
with the following destruction to atoms and formation
of centers for phthalonitrile cyclization.
50
Ethanol
23
35
50
N,N-Dimethyletha-
nolamine
23
35
50
Ethoxyethanol
23
35
50
The authors of [15] studied the formation of a free
phthalocyanine from phthalonitrile in some alcohols at
temperatures close to room temperature and on UV
irradiation of the reaction mixture at different reaction
stages. It was established that UV irradiation is efficient
only at the beginning of the reaction, since heating of
the reaction mixture in the dark followed by UV irradi-
ation did not result in the formation of phthalocyanine.
Ni–Al2O3
23
Methanol
Ethanol
15–25
22–34
35–45
18–30
28–40
32–45
20–34
30–40
32–45
18–27
34–43
30–41
35
50
23
35
50
We performed the comparative study of these reac-
tions in different solvents with the use of two precur-
sors, namely, phthalonitrile and 1,3-D (intermediate
product of phthalonitrile condensation). In the case of
phthalonitrile, we found that in ethylene glycol, the
reaction product is formed in a temperature interval
0−60°C with the yield of phthalocyanine from traces to
quantitative amount (Table 5). However, it is difficult to
determine the practical yield due to an increased vis-
cosity of this solvent (while, for glycerin, it is even
impossible). As with activated metals, the most efficient
solvents among those used were methanol and ethanol;
at 30–60°ë, the use of these solvents provided repro-
ducible quantitative yield, while at 0–25°C, the product
was formed in lower yields of 5–65%. Ethoxyethanol
and DME applied in combination with UV irradiation
also provided adequate but lower yields of phthalocya-
nine. Sometime, phthalocyanine did not form after 3 h
or irradiation, but was detected only ~48 h after the pro-
cess termination. At the same time, in parallel experi-
ments without nucleophilic agent or without irradia-
tion, no product was detected or it was detected only in
trace amounts.
N,N-Dimethyletha-
nolamine
23
35
50
Ethoxyethanol
23
35
50
mined from the change in the mass of the inert sub-
strate. Similar problems were observed with zeolites
used as a matrix in the reaction of phthalonitrile
cyclization.
As in the case of “free” activated metals, the use of
metals on the inert substrate resulted in the formation of
the same metal phthalocyaninates of 90–95% purity
due to impossibility of complete separation of the inert
substrate. With metals on the inert substrate, the yields
of phthalocyaninates were somewhat higher (0–15% on
phthalonitrile) as compared to the yields obtained with
nonactivated metals, but were lower, as was expected,
than for Rieke metals. A lower activity of metals on the
inert substrate as compared to that of Rieke metals is
explained by the fact that the organic participant of the
reaction (phthalonitrile) should first penetrate inside
aluminium oxide for further contact with metal aggre-
gates (Fig. 3).
The most efficient solvent in the case of 1,3-D
(Table 6) was DME, where the formation of phthalocy-
anine traces was recorded at í = 7°C; at T = 50–55°C,
the phthalocyanine yield was quantitative and repro-
ducible. Aprotic solvents were used also in the case of
1,3-D, and no activator was required.
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LOW-TEMPERATURE SYNTHESIS OF PHTHALOCYANINE
627
(‡)
(b)
(c)
(d)
Fig. 3. (a) The electron microscopic pictures of agglomerates of the Cu atoms and (c) of the Ni atoms in the structure of Al O
2
3
before treatment in a solution of phthalonitrile and phthalocyanine formed on the matrix of these agglomerates: (b) Cu and (d) Ni.
UV irradiation of alcoholic solutions of phtha- activator. In our opinion, this is the reason of H2Pc
.
lonitrile results in the formation of free radicals RO , formation at low temperatures. When DME is used
.
which favor nucleophilic attack at the C atom of the as a solvent, free (CH3)2NCH2CH2O radicals are
CN group; in the absence of UV irradiation, this formed, and a lone pair at the N atom can participate
attack is performed only by the CH3O– anion of an in nucleophilic attack.
Table 5. The yield of phthalocyanine from phthalonitrile (as precursor) at different temperatures with UV irradiation of the
reaction mixture
The yield, %
Solvent*/Support
Ethylene glycol/DBU
Ethylene glycol/CH3ONa
Ethanol/DBU
Traces Traces Traces <5
Traces Traces Traces <7
17–20 35–40 50–55 100
20–25 32–36 40 60
100
80
100
100
100
100
100
100
100
100
100
100
100
100
0
0
0
Traces Traces 15–20 38–40 45–50 100
100
100
100
100
Ethanol/CH3ONa
Methanol/DBU
Traces Traces 15–22 50–55 70–75 100
100
100
100
Traces Traces <10 20–25 45–55 65–73 100
Traces Traces 10–15 25–30 50–55 70–75 100
Methanol/CH3ONa
DME/DBU
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Traces Traces 80–85 100
<10 50–60 75–80 100 100
Traces Traces 75–80 100
Traces 45–50 65–75 75–80 100
DME/CH3ONa
Ethoxyethanol/DBU
Ethoxyethanol/CH3ONa
0
* No phthalocyanine was discovered in these solvents without the addition of an activator.
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628
KHARISOV et al.
Table 6. The effect of UV irradiation on the formation of phthalocyanine from 1,3-diiminoisoindoline in different solvents
Solvent T, °C Result
7, 20, 45, 65, 75, 85, 100 No visible changes were observed in a system
DMF
DMSO
7, 20, 45, 65, 75
85, 100
No visible changes were observed in a system
CH3ONa
Dark color of a solution without the formation of the precipitate
Trichlorobenzen
Nitrobenzene
7, 20, 45, 65, 75, 85, 100 No visible changes were observed in a system
7, 20, 45, 65, 75
80, 100
No visible changes were observed in a system
Dark color of a solution; the formation of phthalocyanine in small
quantities
DME
71–00
Phthalocyanine is formed within all temperature interval; the intensity
of a solution color and the precipitate amount increase with temperature;
in the absence of irradiation, phthalocyanine is formed only beginning
at 45–50°C
Ethanol, methanol
25, 35, 45
The yields from 10 to 25%
As was noted, solutions of phthalonitrile in poly- this can be explained by the presence of CaCO3, which
atomic alcohols show a tendency (that was not con- is inactive toward phthalocyanine cyclization.
firmed due to a difficulty in separation of the reaction
product and a solvent) to give a higher yield of phthalo-
cyanine as compared to the solvents with one OH
group. Obviously, an increase in the number of the OH
groups leads to an increase in the number of free radi-
cals in a system and thus, to a higher yield of the reac-
tion product. The studies performed indicate the possi-
bility of preparing phthalocyanine at relatively low
temperatures, up to 0°ë in the corresponding proton-
containing solvents.
The scanning electron microscopy data for “blue”
zeolite are shown in Fig. 4. The classical morphology
of clinoptiolite, when crystals grow from the cavity, can
be seen in Fig. 4a. The same zeolite after treatment with
phthalonitrile and cyclization of the latter is shown in
Fig. 4b; the size of a single organic particle is estimated
as 500 nm. The most efficient of the solvents used in
preparing phthalocyanines were methanol, ethanol,
THF, and benzene (Table 7). The final product forms
slowly, within 12–72 h; the reaction rate increases two
to three times on additional ultrasonic treatment. The
product yield on “green” zeolite is more than two times
as low as on “blue” zeolite, other conditions being
equal. The amount of ç2Pc formed in ethoxyethanol
and DME is insignificant. In experiments performed
without zeolites but under the same conditions (72 h),
only traces of phthalocyanine were detected; the yields
in methanol and ethanol vary within 15–30%.
As follows from the comparison of the results
obtained with the data obtained for metals in different
degree of activation, the use of highly active pyrophoric
metals is the most effective condition for cyclization of
phthalonitrile (which provides higher yields). For
instance, the use of pyrophoric nickel in the presence of
water leads to higher NiPc yields. In blank experiments
with the use of “blue” zeolite with some water admix-
ture, no phthalocyanine was formed at all. For low-tem-
perature synthesis of phthalocyanine particular, rather
than its metal complexes, from where a metal (Cu, Ni,
Fe) cannot be extracted without complete destruction of
organic material, the use of zeolites together with UV
irradiation seems to be the most efficient method.
When zeolites were used to synthesize phthalocya-
nines at low temperatures, it was taken into account that
the cavities of zeolites and of the other porous materials
have higher surface energies, which are sufficient, in
our opinion, to initiate cyclization of phthalocyanine at
T = 0–50°C. Recent years have seen publications [14,
29, 30–37] devoted to the synthesis and identification
of phthalocyanines and their metal complexes in cavi-
ties of materials similar to zeolites (clays, alumophos-
phates and mesoporous molecular sieves) and on ultra-
sonic treatment of solid-phase mixtures of phthaloni-
trile and CuCl2 with the formation of Cu
phthalocyaninate [38]. Therefore, we suggest that the
use of ultrasonic treatment of a heterogeneous reaction
in combination with the corresponding solvents and
activators should be the optimum condition for the
microcycle formation process.
Clinoptilolite zeolite [39, 40] used in this work is a
natural mineral. Clinoptilolite was identified as main
phase in “green” and “blue” zeolite forms. Quartz
(SiO2) and calcite (CaCO3) were detected additionally
in “green” form. The percentage of CaO in “green”
form is higher than in “blue” form, was confirmed by
X-ray powder diffraction data. The surface area of
“green” zeolite is higher than that of “blue” zeolite
As was shown, the direct electrochemical synthesis
of metal phthalocyaninates described in [18] can be
optimized with the aim to low the synthesis tempera-
ture up to room temperature. Usually, the direct elec-
(38.4 and 29.6 m2/g, respectively); however, its activity trosynthesis of phthalocyanines and their metal com-
in the studied surface reactions is low. We believe that plexes is carried out by the electrolysis of a phthaloni-
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LOW-TEMPERATURE SYNTHESIS OF PHTHALOCYANINE
629
(‡)
(b)
Fig. 4. The electron microscopic pictures of “blue” zeolite: (a) classical morphology of clinoptilolite and (b) zeolite covered with
particles of phthalocyanine formed.
trile solution with the anode made of a complex- near the cathode surface (Pt anode) or of Cu phthalocy-
forming metal or platinum at temperatures higher than aninate (Cu anode) in the yield from 5–8% (at 0–2°ë)
80°ë. We used heterogeneous system containing solid to 26–30% (at 20°ë), particularly in the phthalonitrile
phthalonitrile with small amount of a solvent (DME) layers adjacent to the cathode surface. Stirring of the
and an electrolyte, the solid phthalonitrile being in con- reaction mixture reduces the product yield several
tact with a cathode of a large surface area. The process times. Almost no reaction product was detected during
was performed without stirring the reaction mixture at the electrolysis of a saturated solution of phthalonitrile
5–10 µA. It was noted visually the electrolysis at 0– in DME without a solid phase of phthalonitrile. In the
20°ë resulted in the formation of free phthalocyanine case of the other solvents (the ë1–ë8 alcohols) and
Table 7. The yields of H2Pc on zeolite matrices in different solvents and at different temperatures
The yield of phthalocyanine, wt %**
Zeolite
“Blue”
T, °C*
benzen
methanol
ethanol
1-propanol 1-pentanol 2-butanol
THF
0
5
10–15
20–24
23–26
20–27
35–42
55–60
54–65
60–64
65–70
12–17
17–22
25–30
32–35
40–45
60–68
65–73
65–72
70–76
10–12
16–20
23–30
30–36
37–40
60–65
66–70
60–72
65–75
5–8
5–10
10–15
16–20
20–25
25–32
48–55
55–59
55–60
57–65
7–11
11–17
15–20
20–27
32–35
45–55
52–55
50–58
58–65
11–15
18–24
21–25
22–28
33–43
52–60
55–65
57–63
60–64
13–17
18–20
25–30
32–35
50–54
50–57
52–59
55–60
Traces
5–12
10
15
20
25
30
35
40
0–15
20
25
30
35
40
“Green”
7–11
20–26
20–25
20–27
22–28
10–17
25–28
25–30
25–29
26–32
11–16
23–26
25–30
23–28
26–30
7–10
10–18
18–27
20–25
21–25
8–12
14–18
20–25
20–27
20–25
5–11
20–25
18–26
20–24
22–25
15–20
20–28
20–25
22–26
* Treatment time 72 h.
** With the addition of CH ONa as activator. The final yield (on phthalonitrile) was calculated as an average value of 5 independent par-
3
allel experiments.
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630
KHARISOV et al.
under the temperature regime used, the reaction prod-
uct did not form at all. The electrode processes for the
electrolysis with the Cu anode can be presented by the
following reactions (ROH = N,N-dimethyletha-
noalamine, PN = phthalonitrile):
ACKNOWLEDGMENTS
The authors are grateful to CONACyT (Mexican
Agency for Science and Technology, project
no. 39,558-Q) and Universidad Autonoma de Nuevo
Leon (UANL. Monterrey, Mexico, project PAICyT) for
financial support.
Cathode: 4PN + 2e– + 2ROH
PcH2 + 2RO–
Anode: M0 – 2e–
M2+
REFERENCES
1. Linstead, R.P. and Lowe, A.R., J. Chem. Soc., 1934,
M2+ + PcH2
PcM + 2H+,
p. 1016.
2. Byrne, G.T., Linstead, R.P., and Lowe, A.R., J. Chem.
Soc., 1934, p. 1017.
H+ + RO–
ROH.
3. Linstead, R.P. and Lowe, A.R., J. Chem. Soc., 1934,
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