Convenient and efficient method for the synthesis of phthalocyanines and metallophthalocyanines in task-specific 2-hydroxyethyl ionic liquids

Article abstract of DOI:10.1080/00397911.2013.867505

Tetramerization of substituted phthalonitriles in task-specific 2-hydroxylethyl-based imidazolium and ammonium ionic liquids at 100 °C gave corresponding phthalocyanines in moderate yield. Further the reaction of substituted phthalonitriles in the presence of transition-metal salts in ionic liquids gave the corresponding metallophthalocyanines. The 2-hydroxylethyl ammonium ionic liquids gave better yields of phthalocyanines than 2-hydroxylethyl imidazolium and nonhydroxyl functionalized ionic liquids. The isolation and separations of different phthalocyanines were accomplished by silica-gel column chromatography, and products were characterized by various spectroscopic techniques.

Full text of DOI:10.1080/00397911.2013.867505

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Convenient and Efficient Method for
the Synthesis of Phthalocyanines and
Metallophthalocyanines in Task-Specific
2-Hydroxyethyl Ionic Liquids
Kumar Karitkey Yadav a , Poonam a & Shive M. S. Chauhan a
a Bioorganic Research Laboratory, Department of Chemistry ,
University of Delhi , Delhi , India
Accepted author version posted online: 04 Apr 2014.Published
online: 28 Jul 2014.
To cite this article: Kumar Karitkey Yadav , Poonam & Shive M. S. Chauhan (2014) Convenient
and Efficient Method for the Synthesis of Phthalocyanines and Metallophthalocyanines in
Task-Specific 2-Hydroxyethyl Ionic Liquids, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 44:19, 2797-2807, DOI:
10.1080/00397911.2013.867505
To link to this article: http://dx.doi.org/10.1080/00397911.2013.867505
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Synthetic Communications1, 44: 2797–2807, 2014
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2013.867505
CONVENIENT AND EFFICIENT METHOD FOR THE
SYNTHESIS OF PHTHALOCYANINES AND
METALLOPHTHALOCYANINES IN TASK-SPECIFIC
2-HYDROXYETHYL IONIC LIQUIDS
Kumar Karitkey Yadav, Poonam, and Shive M. S. Chauhan
Bioorganic Research Laboratory, Department of Chemistry, University of
Delhi, Delhi, India
GRAPHICAL ABSTRACT
Abstract Tetramerization of substituted phthalonitriles in task-specific 2-hydroxylethyl-
based imidazolium and ammonium ionic liquids at 100 ꢀC gave corresponding phthalocya-
nines in moderate yield. Further the reaction of substituted phthalonitriles in the presence
of transition-metal salts in ionic liquids gave the corresponding metallophthalocyanines.
The 2-hydroxylethyl ammonium ionic liquids gave better yields of phthalocyanines than
2-hydroxylethyl imidazolium and nonhydroxyl functionalized ionic liquids. The isolation
and separations of different phthalocyanines were accomplished by silica-gel column
chromatography, and products were characterized by various spectroscopic techniques.
Keywords 2-Hydroxyethyl ionic liquids; metal salts; phthalocyanines; phthalonitriles;
tetramerization
INTRODUCTION
Ionic liquids are widely used as a green reaction media to replace the conven-
tional organic solvents in chemical and catalytic reactions,[1,2] separation and purifi-
cation processes,[3] and biomedical fields.[4] The appropriate combination of organic
cations and anions may modify the property, specificity, and reactivity of ionic
liquids[5] to serve the dual roles of catalyst and reaction media. The replacement
Received July 24, 2013.
Address correspondence to Shive M. S. Chauhan, Bioorganic Research Laboratory, Department of
Chemistry, University of Delhi, Delhi 110007, India. E-mail: smschauhan@chemistry.du.ac.in
2797

2798
K. K. YADAV, POONAM, AND S. M. S. CHAUHAN
of conventional organic bases with basic ionic liquids are due to their flexible,
nonvolatile, noncorrosive, immiscible, highly catalytic efficient, environmentally
friendly, and reusable properties.[6] Basic ionic liquids are important task-specific
ionic liquids used in base-catalyzed processes such as Michael addition,[7]
Markovnikov addition,[8] Knoevenagel condensation,[9] Mannich reactions,[10] and
various other base-catalyzed reactions. The basic ionic liquids enhance the
nucleophilicity and the rate of reaction for nucleophilic substitution reactions in
comparison to organic solvents.[11,12] The 2-hydroxylethyl ionic liquids are an impor-
tant class of task-specific ionic liquids. They have increased solvent polarity and sol-
vation properties similar to volatile alcohols in many organic transformations such
as preparation of nonmaterial[13,14] and material chemistry.[15] The use of
task-specific ionic liquids as a green reaction medium offers an efficient solution to
both the solvent emission and catalytic recycling problems.[16]
Phthalocyanines are well known because of their wide applications including
use in chemical sensors, dyes, catalysts, liquid crystals, and biomedical fields.[17,18]
A decisive disadvantage of phthalocyanines is their poor solubility in organic
solvents and water. To increase the solubility, alkyl or alkyloxy substituents are
introduced at peripheral positions of phthalocyanine framework. The tetrameriza-
tion of phthalonitriles in high boiling solvents such as, dimethylformamide, penta-
nol, dichlorobenzene, and ethylene glycol are general methods for the synthesis of
phthalocyanines. These methods require strong base and metal salts as a cata-
lyst.[19,20] Previously, we have explored the synthesis of metal-free[21] and metallated
phthalocyanines using functional imidazolium-, ammonium-, and pyridinium-based
ionic liquids in combination with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a
strong base. The use of such organic bases in reaction causes additional cost and
environmentally hazardous conditions;[22] hence it is desirable to use task-specific
basic ionic liquids[23] instead of hazardous organic bases.
Herein, we report the synthesis of phthalocyanines in task-specific basic ionic
liquids, avoiding the use of strong and expensive DBU and related organic bases,
thereby preventing the reaction from various disadvantages such as no catalyst
recovery, corrosion, and waste production. This method involves a greener approach
for the synthesis of highly valuable phthalocyanines at lower temperature in high
purity than other methods[24] and offers a trouble-free workup procedure.
RESULTS AND DISCUSSION
The required task-specific ammonium (2) and imidazolium (3) ionic liquids are
synthesized by modification of known methods and purified by crystallization in
suitable solvents and various other purification processes. The characterizations of
these task-specific ionic liquids are done by infrared (IR), NMR, and other
spectroscopic techniques (Figure 1).
Phthalonitrile 4a in dimethylaminoethanol (1a) with Co(OAc)2 ꢁ 4H2O tetra-
merizes to form phthalocyanine (6a) in 10% yield (Table 1), whereas the tetrameriza-
tion of phthalonitrile 4a in dimethylaminopropanol (1b) gave 6a in 2% yield only.
The appearance of a characteristic soret band at 337 nm and intense Q bands at
602 nm and 665 nm in ultraviolet–visible (UV-vis) spectrum indicates the formation
of phthalocyanine 6a in the reaction.[21] In the infrared (IR) spectrum, the absence of

SYNTHESIS OF PHTHALOCYANINES
2799
Figure 1. Structure of functional ionic liquids.
Table 1. Tetramerization of phthalonitrile 4a in different ionic liquids (1–3) at 100 ꢀC in the presence of
Co(OAc)2 ꢁ 4H2Oa
S. no.
Phthalonitrile
Phthalocyanine
Ionic liquid
Yield (%)b
1
2
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
6a
la
lb
10
2
3
2a
2b
2c
2d
2e
2f
6
62
4
5
84, 81c, 76c
6
61
0
7
8
60
30
22
44
25
9
9
2g
2h
2i
10
11
12
13
14
15
16
17
18
2j
3a
3b
3c
3d
3e
3f
6
30
12
72
22
aReaction condition ratio, phthalonitrile (4a)–ionic liquid–metal salt ¼ 1:1:0.25 in 2 h.
bIsolated yields.
cThe same ionic liquid was reused for each consecutive run.

2800
K. K. YADAV, POONAM, AND S. M. S. CHAUHAN
CN and NH stretching bands at ꢂ2200 cmꢃ1 and 3200–3300 cmꢃ1 respectively con-
firmed the complete conversion of 4a into 6a. A peak at m=z 572.32, corresponding
to [M þ H]þ in the electrospray ionization–mass spectrometry (ESI-MS) spectrum
confirmed the formation of 6a in the reaction (Scheme 1).
The roles of anions attached to ionic liquids were examined by carrying out the
reaction in different ionic liquids. Tetramerization of phthalonitrile 4a in 1-butyl-3-
methylimidazolium bromide [bmim][Br] (3a) and 1-butyl-3-methylimidazolium tetra-
fluoroborate [bmim][BF4] (3b) gave phthalocyanine (6a) in 9% and 6% yields respect-
ively. The same reaction in 1-butyl-3-methylimidazolium acetate [bmim][CH3COO]
(3d) (Table 1) gave phthalocyanine (6a) in 12% yield, signifying the role of anions
in the reactions. As the anion was more basic, the yield of the product increased.
The imidazolium ionic liquids in the absence of hydroxyalkyl group may catalyze
the reaction either by direct involvement of anion in the reaction or its ability to
show stronger hydrogen bonded interaction with cyano group of phthalonitriles.
The [bmim][Br] and [bmim][BF4] ionic liquids show hydrogen bonding interac-
tions,[25] whereas the greater yield in ionic liquids 3c and 3d clearly indicates the
direct involvement of more basic anion in the reaction.
Further to enhance the catalytic efficiency of the reaction, we have moved
towards hydroxyl-based task-specific ionic liquids. The reaction medium plays an
important role in determining the rate of a chemical reaction, mainly when anionic
species are involved. We have synthesized the task-specific imidazolium ionic liquids
3e and 3f by introduction of hydroxyl alkyl groups. Phthalonitrile 4a in the presence
of ionic liquid 3e and Co(OAc)2 ꢁ 4H2O tetramerizes to form phthalocyanine 6a in
72% yield, whereas the same reaction in ionic liquid 3f gave 6a in 22% yield only
(Table 1). From the literature[26,27] it is clear that the presence of hydroxyl group
in imidazolium cation makes it a better hydrogen bond donor than C-2 hydrogen
of imidazolium; therefore a strong hydrogen-bonded interaction is obtained between
anion and hydroxyl of cation. These ionic liquids 3e–3f may involve an alkoxide type
of mechanism by showing the hydrogen bonding network (Scheme 2) and provide
better yields than non-hydroxyl-based ionic liquid 3d.
Scheme 1. Synthesis of phthalocyanines.

SYNTHESIS OF PHTHALOCYANINES
2801
Scheme 2. Proposed mechanism.
The change of imidazolium ion with bulkier tetraalkylammonium cation is less
prone to Coulomb interactions, which again increases the nucleophilicity of the
anions. To explore the role of anions in ionic liquids, task-specific ionic liquids were
designed and synthesized by introduction of the hydroxylethyl group as an ethanol
group attached to the ammonium-based ionic liquids (Figure 1, 2a–2j). The yields for
the tetramerization of phthalonitrile 4a at 100 ꢀC in task-specific ammonium ionic
liquids (2a–2j) are mentioned in Table 1. The trend for the anions giving the
maximum yield of phthalocyanine (6a) in ionic liquids (2a–2d) follows the order
CH3COOꢃ > C7H15COOꢃ > OHꢃ > Brꢃ, corresponding to the nucleophilicity of
the anion. The introduction of long-chain octanoate anion in (2-hydroxyethyl)

2802
K. K. YADAV, POONAM, AND S. M. S. CHAUHAN
dimethylammonium octanoate [hyeda][C7H15COO] (2d) gave lower yield in
comparison to (2-hydroxyethyl)dimethylammonium acetate (2f), due to the presence
of a bulky group, which reduced the nucleophilicity of octanoate ion (Table 1).
Further, the effect of change of anion in combination with hydroxylethyl group
of ammonium cation was studied. Increase in the yield of the phthalocyanine 6a was
observed on changing the anion from methyl sulfate to formate to acetate in ionic
liquids 2h, 2g, and 2i, which confirms the fact that ionic liquids that have a hydroxyl
group in combination with strong basic anion (2i) (strong conjugate base) show better
potential as organic solvents in comparison to the one having weak basic anion (2g)
(weak conjugate base) (Table 1), which was further confirmed by using ionic liquid 2h
(possessing much weaker basic anion), thereby giving phthalocyanine in only 22%
yield (Table 1). To compare the role of hydroxylethyl group attached to nitrogen
atom in ammonium-based ionic liquids, the same reaction was carried out using ionic
liquids 2d and 2e. It is interesting to observe that the reaction in ionic liquid 2d gave
phthalocyanine in 61% yield, while the reaction in ionic liquid 2e (which does not
contain any hydroxyl group) could not lead to the formation of the desired phthalo-
cyanine. Similar results were obtained by using imidazolium-based ionic liquid 3d–3e
(Table 1). This clearly indicate the generation and involvement of alkoxide ion in the
reaction (Scheme 2) as the most stable anion (least basic, i.e., methyl sulfate and
formate) in combination with hydroxylethyl cation gives minimum yield. The least
stable anion (most basic, i.e., acetate) in combination with hydroxylethyl cation gives
maximum yield of phthalocyanine 6a (Table 1). The 2-hydroxypropyl ionic liquids (2j
and 3f) gave lower yield of phthalocyanines as compared with their corresponding
2-hydroxyethyl ionic liquids (2c and 3e) (Table 1). Thus the imidazolium ionic liquids
show interactions with phthalonitriles in the reaction medium and give lower yields of
phthalocyanines as compared with ammonium ionic liquids.
To explore the generality of this procedure, a series of substituted phthalocya-
nines were synthesized under the given reaction conditions by using 1 equivalent of
ionic liquid 2c (Scheme 1). Increasing the amount of ionic liquid does not affect the
yield of phthalocyanine. Phthalonitriles (4a–i) were tetramerized in presence of
cobalt acetate and ionic liquid 2c to their corresponding phthalocyanine (6a–i) in
moderate yield. These results are summarized in Table 2. The structures of all pro-
ducts were characterized by spectroscopic analysis and these results were in satisfac-
tory agreement with their literature values.[21]
The core metal of phthalocyanine had been changed with various metals in the
presence of corresponding metal salts. In the presence of 2-hydroxylethyl ammonium
ionic liquid 2c and metal salts, phthalonitrile 4a tetramerizes to give corresponding
metallophthalocyanines in efficient yield (Scheme 1). The results are summarized in
Table 3. The structures of all metallophthalocyanines were confirmed by various
spectroscopic techniques.[21] The tetramerizations of phthalonitriles in ionic liquid
2c with metal salts depend on the substituent of phthalonitriles and types of metal
salts. Metal ions in reaction media coordinate with cyano groups of phthalonitrile
and facilitate the attack of ionic liquid on nitrile group (Scheme 2). Thus the metal
ion in reaction acts as template and favors the cyclotetramerization of phthalonitrile,
thus increasing the yields of the reaction.[28]
The efficient ionic liquid 2c was further used to synthesize the unmetallated
phthalocyanine. In the presence of 2-hydroxyethyl ammonium ionic liquid 2c,

SYNTHESIS OF PHTHALOCYANINES
2803
Table 2. Tetramerization of substituted phthalonitriles in ionic liquid 2c at 100 ꢀC in the
presence of Co(OAc)2 ꢁ 4H2Oa
S. no.
Phthalonitrile
Phthalocyanine
Yield (%)b
1
2
3
4
5
6
7
8
9
4a
4b
4c
4d
4e
4f
6a
6b
6c
6d
6e
6f
84
82
82
80
78
72
70
60
78
4g
4h
4i
6g
6h
6i
aReaction condition ratio, phthalonitrile (4a–4i)–ionic liquid (2c)–metal salt ¼ 1:1:0.25 in 2 h.
bIsolated yields.
Table 3. Tetramerization of phthalonitrile 4a in ionic liquid 2c with different metal salts at 100 ꢀCa
S. no.
Phthalonitrile
Phthalocyanine
Metal salt
Yield (%)b
1
2
3
4
5
6
7
4a
4a
4a
4a
4a
4a
4a
6a
7a
Co(OAc)2 ꢁ 4H20
Zn(OAc)2 ꢁ 2H20
Ni(OAc)2 ꢁ 4H20
Pb(OAc)2
84
86
76
64
62
74
80
8a
9a
10a
11a
7i
FeCl3
Cu(OAc)2 ꢁ H2O
Zn(OAc)2 ꢁ 2H2O
aReaction condition ratio, phthalonitrile–ionic liquid (2c)–metal salt ¼ 1:1:0.25 in 2 h.
bIsolated yields.
phthalonitriles (4a–g) tetramerize to form unmetallated phthalocyanine (5a–g). The
results are summarized in Table 4. The structures of all unmetallated phthalocya-
nines are confirmed by IR and UV-vis spectroscopy. According to the results, the
tetramerization reactions in the absence of metal salts gave lower yields of phthalo-
cyanines in comparison with metallophthalocyanines because there was no template
effect of metal ions. Metallation of metal free phthalocyanine 5a was also carried out
Table 4. Tetramerization of phthalonitrile 4a in ionic liquid 2c without metal salts at 100 ꢀCa
S. no.
Phthalonitrile
Phthalocyanine
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
4a
4b
4c
4d
4e
4f
5a
5b
5c
5d
5e
5f
2
62
54
58
58
56
54
46
48
2.5
2.5
2.5
2.5
3
4g
4h
5g
5h
2.5
2.5
aReaction condition ratio, phthalonitrile–ionic liquid (2c) ¼ 1:1.
bIsolated yields.

2804
K. K. YADAV, POONAM, AND S. M. S. CHAUHAN
in the efficient ionic liquid 2c. The metallophthalocyanines 6a, 7a, 8a, 9a, and 10a are
obtained in 99%, 92%, 98%, 94%, and 90% yields, respectively.
The recyclability of ionic liquid 2c was examined for the synthesis of 6a (Table 1).
After the completion of reaction, the ionic liquid 2c was recovered from the reaction
mixture by washing the crude product with chloroform. Chloroform was evaporated
at 40 ꢀC under reduced pressure, and the resultant ionic liquid was reused three times
for the synthesis of 6a (Table 1). Further, the spectral data of recovered ionic liquid
was found to be identical with unused ionic liquid. The results show that no substantial
decrease in the yield of 6a was observed in a second run (81%). In a third run, using the
recovered ionic liquid 2c by the same procedure, 6a was obtained in 76% yield from 4a.
The other ionic liquids were recovered by washing the reaction mixture with water,
and water was removed using reduced pressure. Therefore these ionic liquids can be
easily used for further runs with an advantage of convenient and trouble-free workup.
A basic ionic liquid acting both as the solvent and base would make the pro-
cedure much easier to handle. The fact that better yields of phthalocyanines were
obtained in strongly basic hydroxyl ionic liquids in comparison to other ionic liquids
could be explained by the involvement of the anion present in the basic ionic liquid.
The anion affects the reaction in two ways: (1) The anionic species present in the
ionic liquid could directly attack one of the cyano groups of the phthalonitrile to
form phthalocyanine. (2) The anion abstracts the proton from hydroxyl group to
generate the alkoxide ion[29,30] (in hydroxylated ionic liquids) or ylide type
nucleophilic species (in imidazolium-based ionic liquids) and attacks one of the
cyano groups of the phthalonitrile, leading to the formation of imidoisoindoline-type
intermediates, which further react with other phthalonitriles and tetramerizes to give
the corresponding phthalocyanines (Scheme 2).
The greater yields of phthalocyanines in ammonium-based ionic liquid having
the combination of both ethanolic group and acetate ion are due to the dual effect of
the hydrogen-bonded interaction of acetate ion with the hydrogen present at
hydroxyl terminal of ammonium cation and the stronger conjugate base of acetic
acid in ionic liquid 2c (species A in Scheme 2). The 2-hydroxyethyl ionic liquids form
the favorable eight-membered stable cyclic transition state A (stable chair confor-
mation) with acetate anion and generate the alkoxide ion more easily as compared
to 2-hydroxypropyl ionic liquids (2j and 3f), which forms less stable nine-membered
cyclic transition state (Scheme 2). The involvement of alkoxyethyl anion in the reac-
tion was further confirmed by treating the ionic liquid 2c with t-butyl chloride for 5 h
at 60 ꢀC under N2 atmosphere. The formation of species B in the medium proves the
generation of alkoxide ion in the reaction medium. The species B in the reaction was
characterized by the shifting of CH2O proton of ionic liquid 2c from 4.09 ppm to
1
3.96 ppm in H NMR and the appearance of characteristic peak at 202.23 [M-Cl]þ
in ESI-MS. Based on these experimental results, a reaction mechanism for the tetra-
merization of phthalonitriles has been proposed using 2-hydroxylethyl ammonium
ionic liquid (2c) (Scheme 2).
EXPERIMENTAL
1
The H NMR spectra were recorded on a Jeol 400-MHz spectrometer using
Tetramethylsilane (TMS) as internal standard, and the chemical shifts (d) are

SYNTHESIS OF PHTHALOCYANINES
2805
expressed in parts per million (ppm). IR spectra were recorded on a Perkin–Elmer
Spectrum 2000 infrared spectrophotometer. UV-visible spectra were recorded on a
Perkin–Elmer Lambda 35 UV=vis spectrophotometer. The mass spectra (EI-MS)
were recorded on a Jeol SX-102DA-6000 (6 kV, 10ma) spectrometer, and ESI-MS
spectra were recorded on a Micromass LCT KC 455 spectrometer (þve mode).
Phthalonitrile (4a), 4-nitrophthalonitrile (4i), and N,N0-dimethylaminoethanol (1a)
were obtained from Spectrochem Pvt. Ltd., and 4-methylphthalonirile (4b) was
obtained from Aldrich. N,N0-Dimethylaminopropanol (1b) was obtained from
Alfa-Aessar. The 4-methoxyphthalonitrile (4c), 4-butyloxyphthalonitrile (4d),
4-octyloxyphthalonitrile (4e), 4-dodecyloxylphthalonitrile (4f), 4-octadecyloxyphtha-
lonitrile (4g), and 4-(p-tert-butylphenoxy)phthalonitrile (4h) are synthesized from
4-nitrophthalonitrile by following the literature procedures. Ionic liquids 2 and 3
were prepared by minor modifications of the literature procedure. All reactions were
carried out under N2 atmosphere except where mentioned. All other solvents and
reagents were used as received. All phthalocyanines are known compounds, and
their analytical data were identical to those reported in different literature studies.
Synthesis of Metallophthalocyanines
A mixture of desired phthalonitrile (4a–i, 200 mg) and corresponding metal
salts (0.25 equivalents) were stirred at 100 ꢀC with functional ionic liquid 2c
(1 equivalent) for the appropriate time (Tables 1–3). The progress of the reaction
was monitored by thin-layer chromatography (TLC) and UV-visible spectroscopic
analysis. When reaction was completed, the mixture was cooled to room tempera-
ture, and distilled water (50 mL) was added to dissolve the functional ionic liquid.
The blue-green solid mass was filtered and the aqueous filtrate was evaporated using
reduced pressure to recover the pure ionic liquid for further use. The solid mass was
further washed thoroughly with H2O–MeOH (1:1, 100 mL) to remove the colorless
impurities and metallophthalocyanines are obtained in pure form. All of the phtha-
locyanines are known compounds and their purities were confirmed by UV-visible
spectroscopic analysis and further comparison with literature.
Phthalocyaninatocobalt(II) C32H16N8Co (6a)[21c]
IR (nujol): 3076, 3021, 1654, 1608, 1479, 1426, 1162, 1270, 1090, 913, 805, 764,
733 cmꢃ1. UV-vis (DMF): kmax (log e) 282.84 (4.71), 328.11 (4.71), 602.91 (4.42),
666.4 nm (5.09). Analysis: calcd. for C32H16N8Co: C, 67.26; H, 2.82; N, 19.61.
Found: C, 67.44; H, 2.96; N, 19.92. MS (ESI): m=z calcd. for C32H16N8Co:
571.08. Found: 572.32 [MþHþ].
CONCLUSION
A simple, efficient, convenient, and environmentally benign procedure for the
synthesis of functionalized phthalocyanines by tetramerization of substituted phtha-
lonitriles in different task-specific basic ionic liquids at lower temperature has been
developed. In comparison with nonhydroxyl ionic liquids, hydroxyl functionalized
ionic liquids give better yields. The 2-hydroxylethyl ammonium ionic liquids give

2806
K. K. YADAV, POONAM, AND S. M. S. CHAUHAN
better yields than 2-hydroxylethyl imidazolium ionic liquids. In the reaction medium
metal ion acts as template and increases the tetramerization of phthalonitriles.
Thus metallophthalocyanines are obtained in better yields than unmetallated
phthalocyanines.
FUNDING
We thank the Department of Science and Technology and University of Delhi,
Delhi, for financial assistance. K. K. Yadav and Poonam are also thankful to the
University Grants Commission, New Delhi, for junior and senior research
fellowships, respectively.
SUPPORTING INFORMATION
Supplemental data for this article can be accessed on the publisher’s website.
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