An efficient synthesis of phthalocyanines based on an unprecedented double-addition of oximes to phthalonitriles

Article abstract of DOI:10.1021/ja046759i

A novel and efficient method is reported for the preparation of phthalocyanines from phthalonitrile or its derivatives which utilizes low-cost reagents of hydrolytic stability, high simplicity, and easy accessibility, i.e., oximes, and proceeds via an unprecedented double addition of oximes to the nitrile group. Copyright

Full text of DOI:10.1021/ja046759i

Published on Web 10/28/2004
An Efficient Synthesis of Phthalocyanines Based on an Unprecedented
Double-Addition of Oximes to Phthalonitriles
Maximilian N. Kopylovich,† Vadim Yu. Kukushkin,*,‡ Matti Haukka,§ Konstantin V. Luzyanin,†,‡ and
Armando J. L. Pombeiro*,†
Centro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico, AV. RoVisco Pais,
1049-001 Lisbon, Portugal, Department of Chemistry, St. Petersburg State UniVersity,
198504 Stary Petergof, Russian Federation, and Department of Chemistry, UniVersity of Joensuu,
P.O. Box 111, FIN-80101 Joensuu, Finland
Received June 2, 2004; E-mail: pombeiro@ist.utl.pt
Phthalocyanines (Pcs) and their complexes are compounds of
high industrial importance with a variety of applications,1-3
especially in modern technologies. Surprisingly, the approaches2,4
for their syntheses have not changed substantially since the early
studies by Linstead.5 The most important method is based on the
template reaction between a source of metal (metal, salt, alkoxide,
or metal salt/organic amine) and phthalonitrile (PN), C6H4-1,2-
(CN)2, upon reflux in C3-C8 alcohols at 100-200 °C or in 2-(N,N-
dimethylamino)ethanol at 135 °C.2,4 In particular, NiPcs can be
synthesized from PNs in the presence of Ni2+ salt and an amine
(e.g., quinoline,6 DMF,7 (N,N-dimethylamino)ethanol,8 1,8-diaza-
bicyclo[5.4.0]undec-7-ene,8 and urea9), hydroquinone,10 or alkali.11
The majority of methods are performed at elevated temperatures
and are both energy- and time-consuming; additional activation by
microwave12 or UV irradiation13 has been achieved but requires
special instrumentation. There are only a few reports on the syn-
thesis of metalla-Pcs under rather mild conditions: (i) treatment
with metal salts and hexamethyldisilazane in DMF;14 (ii) condensa-
tion of PNs to the corresponding nonmetalated Pcs in the presence
of solid NaOMe in dry THF followed by their reaction with metal
sources;15 and (iii) condensation of PNs with lithium 2-(N,N-
dimethylamino)ethoxide in 2-(N,N-dimethylamino)ethanol.16 All
these methods, despite their advantages, involve moisture-sensitive
reagents and dry solvents.
Figure 1. Thermal ellipsoid plot of [3]2+
.
Scheme 1
We report herein a novel reaction which gives an efficient method
for the preparation of Pcs and their complexes from PN or its
derivatives. The method utilizes low-cost reagents of hydrolytic
stability, high simplicity, and easy accessibility, i.e., oximes, and
proceeds via an unprecedented double addition of oximes to the
nitrile group.
When NiCl2‚2H2O17 (1 equiv) is refluxed with an oxime
MeR2CdNOH (4 equiv, R2 ) Me, Et) and a PN RR1C6H2(CN)2
(2 equiv, R/R1 ) H/H, Cl/Cl, H/NO2) in acetone for 1 d, an unusual
complex (12+-42+, route A, Scheme 1; the relative position of R/R1
is shown conditionally) is released as its dichloride salt (80-70%
isolated yield), a slightly grayish (almost colorless) solid. The crystal
structures of [1]Cl2-[3]Cl2 (Figure 1 for [3]Cl2; for [1]Cl2 and
[2]Cl2 see Supporting Information) revealed that two ketoximes
were added to one nitrile group of the PN, forming a chelated
moiety resembling one in oxime-based clathrochelates.18
Despite the wealth of chemistry associated with the metal-
mediated addition of a variety of nucleophiles to nitriles,19-21 the
observed addition of two nucleophiles to one nitrile group is the
first example of that kind; previously only 1:1-type additions were
observed. Moreover, this novel type of addition is all the more so
surprising because (i) it has recently been reported22 that PN couples
with a thioether dioxime at a Ni(II) center to form an imine-
appended macrocycle upon conventional19,22 addition of one oxime
OH to one CtN of PN; (ii) we observed that ketoximes at Ni(II)
react with RCN to form (imidoylamidine)Ni(II) complexes.17
The complexes [1]Cl2‚2H2O and [2]Cl2‚2H2O, on heating in the
solid state, undergo an intense blue coloration by converting into
NiPc 5 (30-20% isolated yield upon vacuum sublimation) follow-
ing heating at 200 °C for 8 h. The formation of the phthalocyanine
complexes 5, 6, and 7 (derived from [1]Cl2‚2H2O or [2]Cl2‚2H2O;
[3]Cl2‚2H2O; or [4]Cl2‚2H2O, correspondingly; the relative position
of R/R1 for 7 is shown conditionally) is much more efficient when
(i) [1]Cl2‚2H2O-[4]Cl2‚2H2O is heated with 2 equiv of the
corresponding PN RR1C6H2(CN)2 (200 °C, 8 h, yields 60-50%)
(route B, Scheme 1) or the reaction is performed in refluxing
methanol (ca. 65 °C, 24 h, yield ca. 60%) or (ii) NiCl2‚2H2O is
† Instituto Superior Te´cnico.
‡ St. Petersburg State University.
§ University of Joensuu.
9
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J. AM. CHEM. SOC. 2004, 126, 15040-15041
10.1021/ja046759i CCC: $27.50 © 2004 American Chemical Society

C O M M U N I C A T I O N S
Scheme 2
(see above). Synthesis (ii) proceeds via route D by starting with an
unsymmetrical substituted PN, e.g., the preparation of 13 from
C6H3-1,2-(CN)2-4-OPh.
Acknowledgment. This work was supported by the Foundation
of Science and Technology (FCT) (Portugal) and its POCTI
program (FEDER funded), a NATO Collaborative Linkage Grant,
and the Russian Fund for Basic Research.
Supporting Information Available: Experimental details and
analytical data; X-ray crystallographic data, in CIF format. This material
is available free of charge via the Internet at http://pubs.acs.org.
reacted with 4 equiv of oxime and 4 equiv of PN (100 °C, 8 h,
yield ca. 75%) (route C, Scheme 1). These routes illustrate a novel
approach to metal phthalocyanines involving oximes. Route B in
methanol is the one that operates under the mildest conditions
(65 °C), but route C is even more attractive since it provides a
single-pot method, proceeds still under rather mild conditions, and,
as the others (routes A and B), does not require dry reagents and
solvents.
We also succeeded in conducting the oxime-mediated cyclo-
tetramerization of PNs (C6H4-1,2-(CN)2, C6H2-1,2-(CN)2-4,5-(Cl)2,
or C6H3-1,2-(CN)2-4-OPh) in the absence of any metal source to
achieve metal-free Pcs 11 and 12 (route D, Scheme 2). The reaction
proceeds under conditions similar to those in route C, with isolated
yields of ca. 65-60% (lower by ca. 10-15% relative to NiPcs
whose formation is promoted by the metal PN activating and
template effects).
The cyclotetramerization of PN to give metal-free Pc requires
both a two-electron reduction and the addition of two protons
(+2e-/+2H+ process). Thus, reducing reagents and H+ donors as
hydroquinone and 1,2,3,6-tetrahydropyridine are effective when the
reaction is performed in the melt (ca. 275 °C).2 The application
for the synthesis of Pcs, achieved in this work for the first time, of
the so-called “simple” oximes, which combine reducing and H+-
donor properties (on one hand) with the broad commercial
availability, low cost, and low toxicity or nontoxicity23 (on the other
hand), provides further benefits.
Our preliminary data indicate that Pcs of other metals, e.g.,
Cu(II), Zn(II), and Cd(II), can be obtained by the described method,
which can also be extended to the syntheses of unsymmetrical
(i) metal Pcs and (ii) metal-free Pcs. Synthesis (i) is accomplished
via route B by reacting complexes [1]2+-[4]2+ with PNs R3R4C6H2-
(CN)2 that are different from the PNs used for their preparation,
e.g., reaction of [1]Cl2‚2H2O or [2]Cl2‚2H2O (1 equiv) with 4,5-
dichlorophthalonitrile (2 equiv) to achieve 8, reaction of [2]Cl2‚
2H2O (1 equiv) with 4-nitrophthalonitrile (2 equiv) or [4]Cl2‚2H2O
(1 equiv) with phthalonitrile (2 equiv) to give 9, reaction of
[4]Cl2‚2H2O (1 equiv) with 4-methylphthalonitrile (2 equiv) to
afford 10 (in these products, two of the R/R1 pairs in 5 or 7 have
been replaced by R3/R4). This synthesis can afford a mixture of
unsymmetrical metal Pcs with symmetrical ones since [1]2+-[4]2+
convert into the corresponding symmetrical metal Pcs on heating
References
(1) (a) McKeown, N. B. Phthalocyanine Materials: Structure, Synthesis and
Function; Cambridge University Press: Cambridge, 1998; 200 pp and
references therein. (b) Leznoff, C. C.; Lever, A. B. P. Phthalocyanines:
Properties and Applications; VCH: New York, 1989 (Vol. 1), 1993 (Vol.
2), 1993 (Vol. 3), 1996 (Vol. 4).
(2) McKeown, N. B. Phthalocyanines. In ComprehensiVe Coordination
Chemistry, 2nd ed.; Elsevier: Amsterdam, 2003; Vol. 1, Chapter 1.24,
pp 507-514 and references therein.
(3) de la Torre, G.; Claessens, C. G.; Torres, T. Eur. J. Org. Chem. 2000,
2821 and references therein.
(4) Lindsay, J. S. In The Porphyrin Handbook; Kadish, K. M., Smith, K. M.,
Guiard, R., Eds.; Academic Press: San Diego, CA, 1999; Vol. 1, p 45.
(5) (a) Linstead, R. P. J. Chem. Soc. 1934, 1016. (b) Ficken, G. E.; Linstead,
R. P.; Stephen, E.; Whalley, M. J. Chem. Soc. 1958, 3879.
(6) (a) Wan, W.; Meng, Y. Z.; Zhu, Q.; Tjong, S. C.; Hay, A. S. Polymer
2002, 44, 575. (b) Gurol, I.; Ahsen, V.; Bekaroglu, O. J. Chem. Soc.,
Dalton Trans. 1994, 497.
(7) (a) Kasuga, K.; Asano, K.; Lin, L.; Sugimori, T.; Handa, M.; Abe, K.;
Kikkawa, T.; Fujiwara, T. Bull. Chem. Soc. Jpn. 1997, 70, 1859. (b) Gok,
Y.; Yildiz, S. Z. Polyhedron 1996, 16, 113.
(8) (a) Enokida, T.; Hirohashi, R. Chem. Lett. 1991, 2155. (b) Tomoda, H.;
Saito, S.; Shiraishi, S. Chem. Lett. 1983, 313. (c) Guerek, A. G.; Bekaroglu,
O. J. Chem. Soc., Dalton Trans. 1994, 1419. (d) Blikova, Yu. N.; Ivanov,
A. V.; Tomilova, L. G.; Shvedene, N. V. Russ. Chem. Bull. 2003, 52,
150.
(9) Kreja, L.; Czerwinski, W. J. Mater. Sci. Lett. 1992, 11, 538.
(10) Karabork, M.; Serin, S. Synth. React. Inorg. Metal-Org. Chem. 2002, 32,
1635.
(11) Abe, Y.; Hosoda, T. Jpn. Tokkyo Koho 1972, JP 47031403 19720814;
Application JP 68-96069 19681228; Chem. Abstr. 1973, 78, 17630.
(12) Tolbin, A. Yu.; Ivanov, A. V.; Tomilova, L. G.; Zefirov, N. S. J.
Porphyrins Phthalocyanines 2003, 7, 162.
(13) For a review, see: Kharisov, B. I.; Mendes-Rokhas, M. A.; Ganich, E.
A. Russ. J. Coord. Chem. 2000, 26, 301.
(14) Uchida, H.; Tanaka, H.; Yoshiyama, H.; Reddy, P. Y.; Nakamura, S.;
Toru, T. Synlett 2002, 1649.
(15) Nemykin, V. N.; Kobayashi, N.; Mytsyk, V. M.; Volkov, S. V. Chem.
Lett. 2000, 546.
(16) Leznoff, C.; Hu, M. G.; Nolan, K. J. M. Chem. Commun. 1996, 1245.
(17) Kopylovich, M. N.; Pombeiro, A. J. L.; Fischer, A.; Kloo, L.; Kukushkin,
V. Yu. Inorg. Chem. 2003, 42, 7239.
(18) Voloshin, Y. Z.; Kostromina, N. A.; Kra¨mer, R. Clathrochelates:
Synthesis, Structure and Properties; Elsevier: Amsterdam, 2002.
(19) Kukushkin, V. Yu.; Pombeiro, A. J. L. Chem. ReV. 2002, 102, 1771.
(20) Pombeiro, A. J. L.; Kukushkin, V. Yu. In ComprehensiVe Coordination
Chemistry, 2nd ed.; Lever, A. B. P., Ed.; Elsevier: Amsterdam, 2003;
Vol. 1, Chapter 1.34, pp 639-660.
(21) Michelin, R. A.; Mozzon, M.; Bertani, R. Coord. Chem. ReV. 1996, 147,
299.
(22) Pavlishchuk, V. V.; Kolotilov, S. V.; Addison, A. W.; Prushan, M. J.;
Butcher, R. J.; Thompson, L. K. Chem. Commun. 2002, 468.
(23) (a) Van Helden, H. P. M.; Busker, R. W.; Melchers, B. P. C.; Bruijnzeel,
P. L. B. Arch. Toxicol. 1996, 70, 779. (b) Dawson, R. M. J. Appl. Toxicol.
1994, 14, 317.
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