1132
Published on the web September 23, 2011
Chemoselective Polycondensation of 2-Amino-4,6-dichloro-1,3,5-triazine
with Aromatic Diamines
Yuji Shibasaki,*1 Takanori Koizumi,1 Naoya Nishimura,2 and Yoshiyuki Oishi1
1Department of Chemistry and Bioengineering, Graduate School of Engineering, Iwate University,
4-3-5 Ueda, Morioka, Iwate 020-8551
2Synthesis Research Department, Chemical Research Laboratory, Nissan Chemical Industries, Ltd.,
722-1 Tsuboi-cho, Funabashi, Chiba 274-8507
(Received July 25, 2011; CL-110627; E-mail: yshibasa@iwate-u.ac.jp)
Chemoselective polycondensation of 2-amino-4,6-dichloro-
1,3,5-triazine (ADCT) was investigated with various aromatic
diamines such as 4,4¤-oxydianiline (ODA), 9,9-bis(4-amino-
phenyl)fluorene (BAFL), 4,4¤-(hexafluoropropane-2,2-diyl)di-
aniline (BisAF), and bis(4-aminophenyl)sulfone (SODA) in
the presence of potassium carbonate as a base. High-molecular
weight perfectly linear polyguanamines (Mn µ 46000) were
successfully obtained for the polycondensation of ADCT with
BisAF, while the polycondensation of ADCT with BAFL
afforded branched polyguanamines with a degree of branching
of from 0.02 to 0.17.
NH2
N
NH2
N
K2CO3
NMP
N
N
H2N Ar NH2
H
H
N Ar N
Cl
N
Cl
N
n
ADCT
H2N
NH2
O
H2N Ar NH2
:
H2N
NH2
ODA
BAFL
O
O
F3C CF3
S
H2N
NH2 H2N
NH2
Chemoselective reactions, many of which can be observed
in living organisms, are key techniques in the construction of
complex structures from polyfunctional components. The basic
strategy for chemoselective reaction is the utilization of the
different reactivity in like functional groups such as between
aliphatic amines and aromatic amines. Various types of the
chemoselective reactions are applied to the preparation of
polymers such as polythiophenes,1,2 polyesters,3 and poly-
amides.4 Such controlled reaction affords regioregular structures,
resulting in a variety of higher-ordered polymeric architectures.
Triazine is an aromatic molecule having three nitrogen
atoms. Its derivatives are commonly prepared from cyanuric
chloride, and used for dyes,5 fluorescent brightening agents,6 and
agrochemicals.7 When a monofunctional compound is intro-
duced into cyanuric chloride, the resulting compounds can be
used as difunctional triazine-based monomers for the preparation
of polyguanamines,8,9 polyethers,10 and polythioethers.11 The
interest in polymers that incorporate the amino-s-triazine moiety
is the existence of the strong interaction between polymer main
chains via hydrogen bonding,12 numerous reactive sites along
with the polymer backbone to modify the polymer, or the
application to photopolymers. Therefore, 2-amino-4,6-dichloro-
1,3,5-triazine (ADCT), the monomer of the amino-s-triazine
functional polymer has been extensively studied.13 However,
polycondensation of ADCT with difunctional monomers could
afford branching structure, resulting in low-molecular weight
polymers, or gelation. Because aromatic diamines have less
nucleophilicity than their aliphatic counterparts, polymerization
of ADCT with aromatic diamines were expected to instantly
form a gel. To the best of our knowledge, no report has been
published about the chemoselective polycondensation of ADCT
with aromatic diamines to date, although the expected polymers
would show interesting reactivity toward electrophiles due to
the numerous regularly-aligned amino groups on the polymer
backbone. Here we report the polymerization of ADCT with
BisAF
SODA
Scheme 1. Synthesis of polyguanamines from ADCT with
various aromatic diamines.
Table 1. Summary of polyguanamine synthesisa
Temp Time Yieldb
c
c
d
Run Diamine
Mn
Mw/Mn Mn(NMR)
/°C
/h
/%
1
2
3
4
5
6
7
ODA
150
150
150
180
150
180
150
3
3
24
24
3
>99
80
1500
3600
18
8.8
2.3
10.5
32
1900
4000
14000
20000
1300
37000
®
BAFL
BAFL
BAFL
BisAF
BisAF
SODA
61 14000
59 19000
88
33 46000
50
1000
12
3
2.3
®
®
aConditions: 2.5 mmol of ADCT, 2.5 mmol of diamine
monomer, 5.5 mmol of K2CO3 in 5 mL of NMP. Methanol-
insoluble part. cDetermined by GPC (NMP containing
b
¹1
d
0.01 mol L of LiBr). Determined by NMR.
various aromatic diamines involving ODA, BAFL, BisAF, and
SODA, and the evaluation of the chemoselectivity.
Polycondensation of ADCT with aromatic diamines was
performed in N-methylpyrrolidinone (NMP) in the presence of
potassium carbonate as base as shown in Scheme 1 (see the
Supporting Information about the detail of the experimental
procedures14). The results of the polymerization are summarized
in Table 1. When the polycondensation was conducted using
ODA as a diamine monomer at 150 °C for 3 h, the polymeriza-
tion solution became heterogeneous to form a low-molecular-
weight polymer (Run 1). On the other hand, the polymerization
with BAFL or BisAF afforded soluble high-molecular-weight
polymers. However, in the case of the polymerization using
Chem. Lett. 2011, 40, 1132-1134
© 2011 The Chemical Society of Japan