Novel Efficient Preparative Method for Phthalocyanines from Phthalimides and Phthalic Anhydride with HMDS

Article abstract of DOI:10.1021/jo030201w

A convenient synthesis of peripherally substituted or unsubstituted phthalocyanines having a variety of metals is described. Phthalocyanines can be obtained by heating phthalimides or phthalic anhydride with metal salts, hexamethyldisilazane, a catalytic amount of p-TsOH, and DMF at 150 °C.

Full text of DOI:10.1021/jo030201w

Novel Efficien t P r ep a r a tive Meth od for
P h th a locya n in es fr om P h th a lim id es a n d
P h th a lic An h yd r id e w ith HMDS
SCHEME 1
Hitoshi Uchida, Paidi Yella Reddy,
Shuichi Nakamura, and Takeshi Toru*
Department of Applied Chemistry, Nagoya Institute of
Technology, Gokiso, Showa-ku, Nagoya 466-8555, J apan
phthalocyanines from phthalonitriles with metal salts
and hexamethyldisilazane (HMDS). We now report a
toru@ach.nitech.ac.jp
Received J une 18, 2003
5
novel convenient synthesis of phthalocyanines directly
from phthalimides and phthalic anhydride by the action
of HMDS under mild conditions.
Abstr a ct: A convenient synthesis of peripherally substi-
tuted or unsubstituted phthalocyanines having a variety of
metals is described. Phthalocyanines can be obtained by
heating phthalimides or phthalic anhydride with metal salts,
hexamethyldisilazane, a catalytic amount of p-TsOH, and
DMF at 150 °C.
6
We have recently reported the high-yield synthesis of
N-substituted imides on treatment of amic acids with
HMDS. In the case of transformation of phthalic anhy-
dride to N-substituted phthalimides in the presence of
ZnBr , we occasionally observed the formation of a trace
2
amount of phthalocyanine-like blue material along with
almost quantitative yield of phthalimide derivatives. We
studied the reaction conditions using HMDS for the
preferential transformation of phthalimides to phthalo-
cyanines (Scheme 1). The results under various reaction
conditions are summarized in Table 1.
Phthalocyanines find versatile application in the area
of material science because of their distinctive optical and
electrical properties as well as their chemical and thermal
7
1
stability. Phthalocyanines are prepared from phthaloni-
2
triles or phthalic acid analogues such as phthalimides,
3
As shown in the reaction with 0.25 equiv of CuCl2,
phthalic anhydrides, and phthalic acids. A number of
DMF should be present for the formation of the phtha-
studies for the application of phthalocyanines to func-
1
locyanine framework and the amount of DMF was
apparently crucial in the high-yield formation of phtha-
locyanine Cu -2, where 1.0 equiv with respect to phthal-
imide was an optimized amount (entries 1-4). DMAc
could be used instead of DMF, but the yield of Cu -2 was
better in DMF and no formation of Cu -2 was observed
in DMSO or chloronaphthalene. At least a 4-fold excess
of HMDS was found to be necessary for the good yield
tional dyes have been carried out, generally adopting
the preparation of these peripherally substituted phtha-
locyanines starting from substituted phthalonitriles; the
preparative methods using phthalic acid analogues and
urea generally need drastic conditions, which often cause
undesired contamination with inseparable impurities
4
such as halogenated phthalocyanine. The preparative
methods for phthalocyanine derivatives with high purity
starting from phthalimides or phthalic anhydrides have
long been desired because these starting substrates are
less expensive and more accessible than phthalonitrile
or diiminoisoindoline derivatives. Such methods should
be extremely attractive for the study of new functional
dyes. Recently, we reported a convenient synthesis of
formation of Cu -2 (entries 2, 6, 8, and 9). Cu -2 was not
8
yielded without p-TsOH (entry 5). Concentrated H
2
SO
4
was also effective (entry 7). Although the formation of
Cu -2 was observed on heating at 100 °C, the reaction at
1
50 °C showed higher yield (entries 2 and 10). An excess
amount of CuCl did not improve the yield (entry 12). In
2
addition, the reaction starting with 5.0 g of phthalimide
under similar conditions produced Cu -2 in 56% yield,
showing that this procedure is compatible with large-
scale production. Furthermore, HMDS is a reagent
widely used as an adhesive agent for photoresists in the
process of manufacturing silicon semiconductors.
*
Fax: +81(52) 735-5217.
(1) (a) Moser, F. H. The Phthalocyanines: Properties; Thomas, A.
L., Ed.; CRC Press: Boca Raton, FL, 1983; Vols. 1 and 2. (b)
Phthalocyanines: Properties and Applications; Leznoff, C. C., Lever,
A. B. P., Eds.; VCH: Weinheim, 1989; Vol. 1, 1993; Vols. 2 and 3, and
1
996; Vol. 4. (c) Thomas, A. L. The Phthalocyanines: Reserch and
Applications; CRC Press: Boston, 1990. (d) McKeown, N. B. Phtha-
locyanine Materials, Synthesis, Structure and Function; Cambridge
University Press: Cambridge, 1998. (e) Hanack, M.; Heckmann, H.;
Polley, R. In Methods of Organic Chemistry; Schaumann, E., Ed.; Georg
Thieme Verlag: Stuttgart, 1998; Vol. E9d, pp 717-846. (f) Torre, G.;
Claessesns, C. G.; Torres, T. Eur. J . Org. Chem. 2000, 2821.
To explore the scope and limitations of the present
method, we performed the reaction using other metal
salts such as CuCl, CuBr
2
, CuBr, Cu(OTf)
2
, ZnCl
2
, ZnBr
2
,
.
Zn(OTf) , CoCl , CoBr , NiCl
2
2
2
2
, NiBr , MgCl
2
2
, and MgBr
2
(
2) Linstead, R. P. J . Chem. Soc. 1934, 1016.
Various metallophthalocyanines were obtained in moder-
(3) Wyler, M. U.S. Pat. Appl. 2197458 and 2197459, 1940; Chem.
Abstr. 1940, 34, 37564. For a number of improved preparative methods
reported thereafter, see ref 1. For more recent reports of microwave
irradiation methods, see: (a) Shaabani, A. J . Chem. Res., Synop. 1998,
(5) Uchida, H.; Tanaka, H.; Yoshiyama, H.; Reddy, P. Y.; Nakamura,
S.; Toru, T. Synlett 2002, 1649.
(6) (a) Reddy, P. Y.; Kondo, S.; Toru, T.; Ueno, Y. J . Org. Chem.
1997, 62, 2652. (b) Reddy, P. Y.; Kondo, S.; Fujita, S.; Toru, T. Synthesis
1998, 999.
(7) For a review of HMDS in syntheses, see: Vorbr u¨ ggen, H. Acc.
Chem. Res. 1995, 28, 509.
6
72. (b) Ungurensau, C. Synthesis 1999, 10, 1729. (c) J ung, K. S.; Ro,
J . Y.; Lee, J . Y.; Park, S. S. J . Mater. Sci. Lett. 2001, 20, 2203. (d)
Shaabani, A.; Bahadoran, F.; Bazgir, A.; Safari, N. Indian J . Chem.
Sec. A 2001, 40A, 195 and references therein. (e) Villemin, D.;
Hammadi, M.; Hachemi, M.; Bar, N. Molecules 2001, 6, 831.
(
4) Yao, J .; Yonehara, H.; Pac, C. Bull. Chem. Soc. J pn. 1995, 68,
(8) Reaction of phthalonitrile with HMDS gave 2 without p-TsOH;
see ref 5.
1
001.
1
0.1021/jo030201w CCC: $25.00 © 2003 American Chemical Society
Published on Web 10/08/2003
8
736
J . Org. Chem. 2003, 68, 8736-8738

TABLE 1. P r ep a r a tion of Meta llop h th a locya n in es 2 by Tr ea tm en t of P h th a lim id es 1 w ith Meta l Sa lts, HMDS, p-TsOH,
a n d DMF
HMDS
(equiv)
p-TsOH‚H2O
DMF
(equiv)
reaction
temp (°C)
reaction
time (h)
yield
(%)
entry
MXn
(equiv)
product
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
CuCl2
CuCl2
CuCl2
CuCl2
CuCl2
CuCl2
CuCl2
CuCl2
CuCl2
CuCl2
CuCl2
CuCl2
CuCl
CuBr2
CuBr
Cu(OTf)2
ZnCl2
ZnBr2
Zn(OTf)2
CoCl2
CoBr2
NiCl2
NiBr2
MgCl2
MgBr2
4
4
4
4
6
6
4
3
5
6
6
4
4
4
4
4
4
4
4
4
4
4
4
4
4
0.1
0.1
0.1
0.1
0
0
150
150
150
150
150
150
150
150
150
100
130
150
150
150
150
150
150
150
150
150
150
150
150
150
150
10
10
10
10
12
10
10
12
12
48
48
48
4
10
10
10
10
10
10
10
4
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Cu -2
Zn -2
Zn -2
Zn -2
Co-2
Co-2
Ni-2
0
63
45
10
0
1.0
2.0
4.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.2
0.2
66
60
38
64
45
65
64
63
72
60
71
47
42
61
51
44
53
45
22
34
a
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0
0.1
0.1
0
0.1
0.1
0.1
0.1
0.1
0.1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
b
4
10
10
4
Ni-2
H2-2
H2-2
a
Concentrated H2SO4 (0.2 equiv) was used instead of p-TsOH‚H2O. b CuCl2 (0.375 equiv) was used.
ate to good yields (entries 13-25). In all cases, the
reaction mixture was poured into concentrated H SO to
SCHEME 2
2
4
remove the side products, after the reaction was com-
pleted. As has been already observed in the reaction with
3
urea, the reaction also proceeded with cuprous chloride
9
or bromide, giving Cu(II)-phthalocyanine Cu -2 (entries
1
2 2
3 and 15). Notably, when Cu(OTf) or Zn(OTf) was used
as a metal salt, the reaction proceeded without p-TsOH
giving Cu -2 or Zn -210 in high yields, respectively (entries
1
6 and 19). This is probably because trifluoromethane-
sulfonic acid is formed during the course of the reac-
tion and acts as a catalyst in place of p-TsOH or because
TABLE 2. P r ep a r a tion of P er ip h er a lly Su bstitu ted
P h th a locya n in es 4 fr om P h th a lim id e Der iva tives 3
Cu(OTf)
reaction with magnesium salts, the first formed Mg-2
was hydrolyzed on treatment with concentrated H SO
-2 (entries 24 and 25).
2 2
and Zn(OTf) accelerate the reaction. In the
phthalimide
p-TsOH‚H
2
O
yield
2
4
1
1
entry
R
1
R
2
R
3
MX
n
(equiv)
product (%)
2 2
to give H -phthalocyanine H
1
2
3
4
5
tert-Bu
Cl
Cl
tert-Bu
Cl
H
Cl
H
H
3a CuCl
3b CuCl
2
0.1
0.1
0.1
0.1
0
Cu -4a
Cu -4b
Cu -4c
Zn -4a
Zn -4c
52
43
24
62
34
Since the reaction with HMDS could be performed at
lower temperature than those with ammonia or urea,
isolated phthalocyanines were free from contamination
with halogenated phthalocyanines or other inseparable
side products.12 No contamination with such halogenated
phthalocyanines was confirmed by EI MS and MALDI
TOF MS spectra.
2
2
Cl Cl 3c CuCl
3a ZnCl
Cl Cl 3c Zn(OTf)
H
H
2
2
These phthalocyanine derivatives Cu -4a and Zn -4a were
obtained as a mixture of regioisomers, which were not
separated. Naphthalocyanines Cu -617 and Zn -6 could
also be prepared in moderate yields in the reaction of 2,3-
naphthalimide 5 (Scheme 3).
The present procedure was compatible with phthalim-
ides having a variety of substituents such as 4-tert-butyl-
18
3
3
a , 4,5-dichloro- 3b, and 3,4,5,6-tetrachlorophthalimide
c, giving the corresponding peripherally substituted
1
3
14
15
Cu- and Zn-phthalocyanines Cu -4a , Cu -4b, Cu -4c,
Zn -4a ,13 and Zn -4c in good yields (Scheme 2, Table 2).
16
(13) Mikhalenko, S. A.; Barkanova, S. V.; Lebedev, O. L.; Luk’yanets,
E. A. Zh. Obshch. Khim. 1971, 41, 2735.
(
14) Barrett, P. A.; Bradbrook, E. F.; Dent, C. E.; Linstead, R. P. J .
(9) Dent, C. E.; Linstead, R. P. J . Chem. Soc. 1934, 1027.
Chem. Soc. 1939, 1820.
(
10) Barrett, P. A.; Dent, C. E.; Linstead, R. P. J . Chem. Soc. 1936,
(15) Shigemitsu, M. Bull. Chem. Soc. J pn. 1959, 32, 607.
(16) Birchall, J . M.; Haszeldine, R. N.; Morley, J . O. J . Chem. Soc.
C 1970, 2667.
(17) Lebedev, O. L.; Luk’yanets, E. A.; Puchnova, V. A. Opt.
Spektrosk. 1971, 30, 640.
1
1
719.
(
017.
(
11) Byrne, G. T.; Linstead, R. P.; Lowe, A. R. J . Chem. Soc. 1934,
12) In the reaction with CoCl
2
, CoBr
2 2 2
, NiCl , or NiBr , formation
of a small amount of H
the products.
2
-2 was observed in MALDI-TOF-Ms spectra of
(18) Mikhalenko, S. A.; Luk’yanets, E. A. Zh. Obshch. Khim. 1969,
39, 2554.
J . Org. Chem, Vol. 68, No. 22, 2003 8737

SCHEME 3
CdN double bonds by easy removal of trimethylsilyl
alcohol and ether. In addition, HMDS has sufficient
nucleophilicity toward carbonyl groups of the imide and
the anhydride when activated with a strong protic acid.
These characteristic reaction features of HMDS realized
a novel, convenient synthetic method for peripherally
substituted or unsubstituted phthalocyanines having
various metals from phthalimides and phthalic anhy-
dride.
SCHEME 4
Exp er im en ta l Section
Phthalimide was recrystallized from ethyl acetate. HMDS was
distilled under an argon atmosphere. p-TsOH‚H
under high vacuum. Metal salts were heated under vacuum
before use. DMF was dried over P and distilled under
2
O was dried
2
O
5
vacuum. All solvents for extraction and other reagents were used
as obtained without additional purification.
P r ep a r a tion of Cu -P h th a locya n in e Cu -2.9 A glass tube
2
was charged with phthalimide (100 mg, 0.68 mmol), CuCl (23
TABLE 3. Yield s of Cu -P h th a locya n in e Cu -2 by
Tr ea tm en t of P h th a lic An h yd r id e w ith HMDS
mg, 0.25 mmol), p-toluenesulfonic acid monohydrate (13 mg, 0.07
mmol), and HMDS (560 µL, 438 mg, 2.7 mmol), and the mixture
was stirred at 100 °C for 1 h under an argon atmosphere. The
mixture was cooled, and DMF (50 µL, 0.68 mmol) was added.
Then, the tube was sealed and the mixture was heated at 150
°C. A dark purple solid immediately appeared. After being
heated for 10 h, the mixture was cooled and filtered. The solid
was washed with methanol and then dissolved in concentrated
entry HMDS (equiv) reaction time (h) product yield (%)
1
2
3
4
4
5
5
6
10
4
10
10
Cu -2
Cu -2
Cu -2
Cu -2
33
33
61
62
H
2
SO
The resulting blue precipitates were filtered and washed suc-
cessively with dilute H SO , water, and methanol. The solid was
4
(5 mL). The solution was poured into water (100 mL).
SCHEME 5. P la u sible Rea ction Mech a n ism
2
4
further purified by extraction with methanol by Soxhlet’s
extractor to give 62 mg (63%) of Cu -2 as a blue solid.
The reaction starting with 5.0 g of phthalimide was performed
in a SUS 316 pressure bottle (100 mL Taiatsu Techno Co., Ltd.)
under identical conditions. After separation and purification, 2.7
g (56%) of Cu -2 was obtained.
Phthalocyanines Zn -2, Co-2,10 Ni-2,10
1
0
H
2
-2,11 Cu -4b,
14
1
5
16
17
Cu -4c,
and Zn -4c
and naphthalocyanines Cu -6
and
Zn -618 were prepared as above.
P r ep a r a t ion of Tet r a -ter t-b u t yl-Cu -P h t h a locya n in e
Cu -4a .13 The reaction was carried out as described in the
preparation of Cu -2 except that 4-tert-butylphthalimide (138 mg,
0
.68 mmol) was used. After completion of the reaction, the
precipitates were filtered, washed with methanol, and dissolved
in concentrated H SO . The H SO solution was poured into
Furthermore, this procedure was able to extend the
substrate to phthalic anhydride. We examined the re-
action of phthalic anhydride with HMDS under re-
action conditions similar to those described above and
found that it indeed gave Cu -2 (Scheme 4). This reac-
tion proceeds possibly through the formation of phthal-
imides, showing that another nitrogen source from
HMDS is requisite, and the reaction with a 5- to 6-fold
excess of HMDS resulted in the best yield of 2 as shown
in Table 3.
There are a number of plausible reaction pathways to
form the phthalocyanine framework, and Scheme 5
illustrates one of these pathways. HMDS attacks the
activated carbonyl carbon to give the phthlamide, which
is cyclized to form 1,3-diiminoisoindoline through 3-imi-
noisoindolinone. The diiminoisoindoline is known to give
the phthalocyanine framework under mild conditions.19
It should be noted that HMDS acts as a nitrogen source;
besides, it accelerates the dehydration steps forming the
2
4
2
4
water, and the resulting blue precipitates were filtered. The solid
was further purified by silica gel column chromatography using
benzene/THF (99:1) as an eluent to give 70 mg (52%) of Cu -4a
as a blue solid.
Tetra-tert-butyl-Zn-phthalocyanine Zn -4a 13 was prepared as
above.
Typ ica l P r oced u r e for Cu -P h t h a locya n in e Cu -2 fr om
P h th a lic An h yd r id e. The reaction was performed as described
in the preparation of Cu -2 except that phthalic anhydride (100
mg, 0.68 mmol), CuCl (23 mg, 0.17 mmol), p-toluenesulfonic
2
acid monohydrate (13 mg, 0.07 mmol), and HMDS (700 µL, 548
mg, 3.4 mmol) were used, giving 60 mg (61%) of Cu -2.
Ack n ow led gm en t. This work was partly supported
by a Grant-in-Aid for Scientific Research on Priority
Areas (A) “Exploitation of Multi-Element Cyclic Mol-
ecules” (No. 14044040) from the Ministry of Education,
Culture, Sports, Science and Technology, J apan, and a
grant from the NITECH 21st Century COE Program
“World Ceramics Center for Environmental Harmony”.
(19) Timokhin, G. A.; Kissin, B. I.; Faeshkina, N. N. Appl. Chem.
USSR 1969, 42, 2187.
J O030201W
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738 J . Org. Chem., Vol. 68, No. 22, 2003