Synthesis, crystal structure and thermal properties of phosphorylated cyclotriphosphazenes

Article abstract of DOI:10.1002/ejic.200700785

A convergent approach for the incorporation of arylphosphonate moieties into the cyclotriphosphazene unit is described. The synthesis is based on the reaction of hexachlorocyclotriphosphazene with diethyl 4- hydroxyphenylphosphonate in the presence of anh

Full text of DOI:10.1002/ejic.200700785

FULL PAPER
DOI: 10.1002/ejic.200700785
Synthesis, Crystal Structure and Thermal Properties of Phosphorylated
Cyclotriphosphazenes
Nicolas Lejeune,[a] Isabelle Dez,*[a] Paul-Alain Jaffrès,[b] Jean-Fançois Lohier,[a]
Pierre-Jean Madec,[a] and Jana Sopkova-de Oliveira Santos[c]
Keywords: Cyclotriphosphazenes / Phosphonates / Thermal properties
A convergent approach for the incorporation of arylphos-
phonate moieties into the cyclotriphosphazene unit is de-
drolysis of the hexaphosphonate compound to its hexaphos-
phonic acid analogue is reported. All products were charac-
scribed. The synthesis is based on the reaction of hexachlo- terised by NMR and IR spectroscopy and mass spectrometry.
rocyclotriphosphazene with diethyl 4-hydroxyphenylphos- The thermal stability and degradation behaviour of these
phonate in the presence of anhydrous potassium carbonate.
This reaction is characterised by substitution of the chloride
atoms, which thus produces the hexaarylphosphono deriva-
tive in good yield. The product of this reaction is fully charac-
terised, including a single X-ray diffraction study. The hy-
new compounds were investigated by thermogravimetric
analysis.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
from hexachlorocyclotriphosphazene, and each of them ex-
hibit very different physical and chemical properties de-
pending of the nature of the substituents.[5] To improve the
flame-retardant properties of cyclotriphosphazene-based
additives, the inorganic ring could be connected to aryl- or
vinylphosphonic acid moieties, which are key functionalities
in polymer additives[6] and flame retardants.[7] Incorpora-
tion of phosphate or phosphonate groups into aryloxyphos-
phazenes has been reported by Allcock et al.[8] The phos-
phate compounds show good thermal stability and were
used as thermal additives for polystyrene.[9]
We report here a novel and efficient method for the in-
corporation of arylphosphonate moieties into the cyclotri-
phosphazene unit according to a convergent synthesis
based on the use of diethyl 4-hydroxyphenylphosphonate
(2; Scheme 1). This new strategy, which is achieved in the
presence of anhydrous potassium carbonate,[10] allows the
complete substitution of the chloride atoms present in
Introduction
Despite their easy synthesis and convenient properties,
hydrocarbon polymers suffer from some evident limitations
in a number of applications where mechanical properties,
thermal stability and light–heat or fire resistance are re-
quired. To improve the thermal properties of polymer mate-
rials, the search for fire-retardant molecules represents a
major technological challenge. Traditionally, halogenated
materials have been used as flame-retardant additives. How-
ever, the release of toxic materials, particularly dioxins,
from incineration has led to the removal of chlorinated ma-
terials from the market and to the restriction in the use of
brominated compounds.[1] Compounds containing phos-
phorus have received recent attention, as they generally give
off nontoxic and noncorrosive volatile products during
combustion, and they generate a subsequent char residue.[2]
In some systems, flame-retardant properties can be im-
proved drastically when phosphorus is combined with ni-
trogen.[3] As an example, cyclotriphosphazene compounds
characterised by the presence of an inorganic ring com-
posed of three phosphazene units are attractive candidates
for the next generation of green flame-retardant additives.[4]
Several classes of cyclotriphosphazene can be synthesised
[a] Laboratoire de Chimie Moléculaire et Thio-organique, EN-
SICAEN, Université de Caen Basse-Normandie, CNRS,
6 boulevard du Maréchal Juin, 14050 Caen, France
Fax: +33-2-31-45-28-77
E-mail: isabelle.dez@ensicaen.fr
[b] CEMCA-UMR CNRS 6521, U.B.O.,
6 avenue Victor Le Gorgeu, 29238 Brest cedex 3, France
[c] Centre d’Etude et de Recherche sur le Médicament de Norman-
die, Université de Caen,
5 rue Vaubénard, 14032 Caen, France
Scheme 1. Synthetic routes to 3, 4 and 5.
138
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Eur. J. Inorg. Chem. 2008, 138–143

Synthesis and Properties of Phosphorylated Cyclotriphosphazenes
hexachlorocyclotriphosphazene (1) to afford 3. The crystal
Finally, the conversion of the phosphonate groups to
structure of 3 was solved by single-crystal X-ray diffraction phosphonic acid groups was performed under mild condi-
analysis. Furthermore, the hydrolysis of hexaphosphonate 3 tions in a two-step process involving treatment of 3 with
to its hexaphosphonic acid analogue 4 is reported.
bromotrimethylsilane followed by methanolysis.[16] Phos-
The thermal properties of the phosphorylated cyclotri- phonic acid 4 was isolated in quantitative yield, and its for-
phosphazenes were studied by ATG and compared to those mation was evident from the disappearance of the signals
1
of nonphosphorylated cyclotriphosphazene 5.
corresponding to the ethyl groups in the H and 13C NMR
spectra and by the appearance in the IR spectrum of the
characteristic bands between 2500 and 3500 cm–1 that can
be attributed to the OH and POH stretching vibrations. Its
structure was also confirmed by HRMS spectrometry.
Results and Discussion
Synthesis and Characterisation
Phosphonic acid 4 was obtained by the hydrolysis of 3,
which was synthesised by reaction of diethyl 4-hydroxy-
phenylphosphonate (2) with hexachlorocyclotriphosphaz-
ene (1). Compound 1 was commercially available and 2
could be obtained either in several steps or in one step by
a palladium-catalysed cross-coupling reaction.[11] These ap-
proaches, however, have some disadvantages due to the
presence of the phenol functionality, which can affect the
reactivity.[12] In this work, we adapted a cheaper and
straightforward method based on the catalytic Arbusov re-
action involving an iodoarene or a bromoarene and triethyl-
phosphite in presence of a nickel salt.[13,14] We found that
this method, which needs high thermal activation, was more
reproducible when nickel bromide was used as the catalyst
(Scheme 2). According to this methodology, diethyl 4-hy-
droxyphenylphosphonate (2) was obtained in a one-step re-
action without protection of the phenol group. It is worth
noting that this reaction was successful (76% yield) on a
relatively large scale (production of 10 g of compound 2 in
one batch).
Crystal Structure of 3
Single-crystal X-ray structure determination of arylphos-
phonated cyclotriphosphazene 3, which was crystallized
from a solution of pentane and ethyl acetate as colourless
crystals, was carried out. Details of the data collections are
given in Table 1. Figure 1 shows a view of the asymmetric
unit of 3, which consists of one molecule. The phosphazene
ring is not rigorously planar in the crystal structure; it is
somewhat puckered. Maximum deviation from the mean le-
ast-squares plane was detected at the P2 atom
[0.1084(15) Å]. This deviation has the same magnitude as
that observed by us in a previously solved structure of mono-
chloropentaphenoxycyclotriphosphazene.[17] In that crys-
tal structure, we detected asymmetry in the P–N–P and N–
P–N bond angles of the phosphazene ring, and in the crys-
tal of 3 the same asymmetry exists: the mean of the N–P–
N and P–N–P angles is 117.5(5)° and 121.6(5)°, respectively
(Figure 2, Table 1). The values of the P–N, P–O and O–
Caromatic bond lengths are similar to the values observed in
other structures with phosphazene ring as deposited in the
CSD (Table 1). The phenyl rings lying in the periphery of
the phosphazene unit were assigned the numbers 1 to 6. In
the crystal, a disordered position was detected and refined
for the phosphonate group attached to phenyl ring 2.
Scheme 2. Synthesis of phosphonate 2.
Table 1. Selected bond lengths and angles in 3.
Bond lengths [Å]
The substitution reaction of 1 with phenolate derivative
2 proceeded in the presence of potassium carbonate, which
is a common base used for substitution reactions of
hexachlorocylotriphosphazene by phenolate nucleo-
philes.[10] Under these conditions, arylphosphonated cyclo-
triphosphazene 3 was obtained after 2h in an excellent yield
(82%). No byproduct was detected. The structure of 3 was
established by 31P NMR spectroscopy, and the peaks at
7.5 ppm (intensity of 1) and at 17.7 ppm (intensity of 2) can
be attributed to the phosphazene ring and the arylphos-
phonate groups, respectively. The 13C and 1H NMR spectra
match the structure of 3. The structure of 3 was unambigu-
ously established by its single-crystal structure. It should be
noted that in the presence of potassium phosphate as the
base, the reaction produces only an unidentifiable mixture
of products.[15]
P1–N2
P1–N3
P3–N2
P3–N1
P2–N1
P2–N3
P1–O10
P1–O40
P3–O30
P3–O60
P2–O20
1.579(3)
1.580(3)
1.574(3)
1.582(3)
1.580(3)
1.581(3)
1.582(3)
1.587(3)
1.581(3)
1.584(2)
1.582(2)
P2–O50
1.586(2)
1.459(3)
1.573(3)
1.582(3)
1.411(4)
1.400(4)
1.404(4)
1.409(4)
1.404(4)
1.397(4)
P11–O13
P11–O11
P11–O12
C10–O10
C20–O20
C30–O30
C40–O40
C50–O50
C60–O60
Bond angles [°]
N2–P1–N3
N2–P3–N1
N1–P2–N3
116.96(15)
118.07(15)
117.34(15)
P2–N1–P3
P1–N3–P2
P3–N2–P1
121.01(18)
121.72(18)
122.10(18)
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139

I. Dez et al.
FULL PAPER
Figure 1. Ball-and-stick representation of 3. The hydrogen atoms
were omitted for the clarity and π-stacking interactions are indi-
cated by the lines. Cgi denotes the centre of gravity of the ith ring.
Important thermal agitations were also observed for the
ethyl groups of the arylphosphonate moieties in the 1, 2, 3
and 4 rings. The refinement of the disordered positions for
the ethyl groups was tested, but only one position remained
stable during the refinement.
The π-stacking interactions occur between the phenyl
rings, but they are perturbed in comparison, for example,
to
the
monochloropentaphenoxycyclotriphosphazene.
However, the supplementary weak interactions of H-bond
type are introduced in the crystal packing by the presence
of the P=O motifs of the phosphonate group. Three phenyl
rings (rings 1, 2 and 3) are situated above the cyclic phos-
phazene, and the other three phenyl rings are situated below
the phosphazene ring (rings 4, 5 and 6). The position of the
phenyl rings on each side is such that stacking interactions
occur between them. Above the plane, phenyl rings 1, 2 and
3 are oriented perpendicularly with respect to each other
such that T-shaped π-stacking occurs between the rings.
The H31 hydrogen atom attached to C31 of ring 3 is di- Figure 2. Ball-and-stick representation for two detailed views of the
crystal packing in 3. H-bonding interactions are presented as
dashed lines; hydrogen atoms were omitted for the clarity.
rected into the centre of phenyl ring 2. The distance be-
tween C31 and the centre of gravity of phenyl ring 2 (Cg2)
is about ca. 3.566 Å, and the angle between these two rings
ring 4 and is situated at a distance of 3.950 Å with respect
to the centre of ring 4. The angle between the rings is about
55.28(11)°. Ring 5 leans out and so it is situated outside of
the aromatic cluster. However, in the crystal packing, some
close contacts of a H-bonding nature occur between O53
of ring 5 and C61–H61 from symmetrically related ring 6,
and the distance O53–H61 is ca. 2.390 Å.
is about 72.21(13)°. T-shaped π-stacking also exists between
rings 2 and 1. The H21 hydrogen atom of C21 from ring 2
is oriented into the centre of ring 1 (dC21–Cg1 ca. 3.832 Å).
The angle between the planes of phenyl rings 2 and 1 is
about 77.16(12)°. The π-stacking interaction between
rings 2 and 3 seems to be stronger than that between rings
2 and 1. There are no stacking interactions between rings 1
and 3.
Table 2. Hydrogen bonds in 3.
However, weak electrostatic interactions were observed
between cycle 1 and the P=O group of symmetrically re-
lated molecules (Figure 2). Firstly, C12–H12 bonds to
P11=O13 from symmetrical ring 1 (dH12–O13 ca. 2.484 Å,
Table 2), and secondly, C14–H14 bonds to P41=O43 from
ring 4 (dH14–O43 ca. 2.436 Å, Table 2). On the bottom side,
T-shaped π-stacking is also observed between rings 6 and
4. The H65 atom of C65 is directed into the ring centre of 1.
D–H···A
d(D–H) [Å] d(H···A) [Å] d(D···A) [Å] DHA [°]
C14–H14···O43[a]
C12–H12···O13[b]
C61–H61···O53[c]
0.93
0.93
0.93
2.44
2.48
2.39
3.144(5)
3.267(5)
3.095(4)
132.9
141.9
132.5
[a] Symmetry transformations used to generate equivalent atoms:
–x + 1, –y + 1, –z + 1. [b] –x + 1, –y + 1, –z. [c] –x, –y + 2, –z +
140
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Eur. J. Inorg. Chem. 2008, 138–143

Synthesis and Properties of Phosphorylated Cyclotriphosphazenes
TGA Analyses
Although not necessarily direct, the thermal stability of a
molecule has a significant influence on the fire resistance of
a polymer in which it could be incorporated. The thermal
stabilities of compounds 3 and 4 were estimated by TGA
techniques under a nitrogen atmosphere with a heating rate
of 20 °Cmin–1; the obtained values were compared to those
of nonphosphorylated hexaphenoxycyclotriphosphazene 5.
One of the main questions of interest is the temperature at
which the compound has lost 5% of its original weight
(T5%). Another important factor is the weight of the ce-
ramic-like residue or “char” that remains at a given tem-
perature (defined in terms of the percentage of the original
weight). Although decomposition temperatures and resi-
dues yields as determined by TGA cannot be used directly
to predict flammability, an increase in T5%, or in the char
yield can often decrease the flammability of a material by
reducing the supply of fuel to the flame.[18] Thermogravime-
tric analyses on phosphate-functionalised cyclotriphospha-
zenes, N3P3[OC6H4OP(O)OEt2]3, were carried out under at-
mospheric conditions by Allcock et al., and a T5% value of
240 °C and a residual char yield of 32% at 650 °C were
obtained.[9] Until now, no thermal analysis has been carried
out on phosphonate cyclotriphosphazene, which should
have a good thermal stability.
The TGA curves of compounds 3 and 4 have two weight-
loss regions (Figure 3). For 3, the first weight-loss region
concerns the simultaneous release of 12 ethylene molecules
and 6 water molecules, which result from cleavage of the
ester linkages at high temperature to give the corresponding
acidic functionalities that were instantaneously condensed.
The second degradation step concerns the formation of the
polyphosphate resin. For 4, the first step of decomposition
is related to the release of six water molecules obtained by
the condensation of the hydrogen phosphonate groups. This
method of degradation is beneficial to fire-retardant addi-
tives as no toxic vapour is released, no fuel is supplied to
the flame and the transformation of liquid water to gas oc-
curs as an endothermic process. The second step is similar
to the degradation process of 3 and corresponds to the for-
mation of the polyphosphate resin.
Figure 3. Thermogravimetric analyses of 3, 4 and 5 at a heating
rate of 20 °Cmin–1 under a N2 atmosphere.
Table 3. Thermal properties of cyclotriphosphazene derivatives.
Compound
T5% [°C]
Char at 650 °C [wt.-%]
3
4
5
301
207
359
45
58
3
Conclusions
A convergent scheme for the synthesis of two original
cyclotriphosphazenes functionalised by phosphonate–aryl-
oxy and phosphonic acid–aryloxy groups was developed.
The synthetic strategy involved the use of anhydrous potas-
sium carbonate as the base, and complete substitution of
the chloride atoms present in the hexachlorocyclotriphos-
phazene by arylphosphonate moieties was observed. The
structure of 3 was unambiguously established by single-
crystal X-ray diffraction analysis. Furthermore, the hydroly-
sis of hexaphosphonate 3 into hexaphosphonic acid ana-
logue 4 was reported. Finally, the thermal properties of
these new compounds were evaluated, and the analyses
showed that phosphonic acid 4 has a very interesting ther-
mal behaviour. This compound might be useful as a fire-
resistant additive in polymers.
In comparison, hexaphenoxycyclotriphosphazene
5
Experimental Section
High-field 1H (400 MHz), 13C (100.6 MHz), and 31P (162 MHz)
underwent single-step decomposition, which left less than
4% of the original material as a nonvolatile residue at
450 °C (Table 3). Phosphonate cyclotriphosphazenes 3 and
NMR spectra were obtained with a Bruker AC-400 spectrometer.
4 did not show an improvement in the value of T5% relative The 31P and 13C spectra were proton decoupled. 31P NMR spectra
were referenced to external 85% H3PO4 with positive shifts re-
corded downfield from the reference. 1H and 13C were referenced
to external tetramethylsilane. NMR spectra were obtained in
CDCl3 for 2 and 3 and in CD3OD for 4 with chemical shifts re-
corded in ppm and coupling constants recorded in Hertz. TGA
measurements were carried out with a Perkin–Elmer-7 thermal
analysis system equipped with a PC computer at 20 °Cmin–1 under
an atmosphere of nitrogen. Infrared (IR) spectra were recorded
with a Perkin–Elmer Spectrum One with an ATR accessory. Mass
spectra (MS) and high-resolution mass spectra (HRMS) were ob-
tained with a Waters Q-TOF Micro instruments in electrospray
to that of 5; however, for both 3 and 4, the amount of non-
volatile residue formed at high temperature was important
and the compounds retained 45 and 58% of the original
weight, respectively. It is worth noting that the thermal
analysis of 4 was carried out in air and showed a T5% of
172 °C and 68% char at 650 °C. In terms of TGA behav-
iour, the best additive examined here was phosphonic acid
cyclic trimer 4, which released nontoxic vapour below
400 °C and formed a high char yield in air or under an
atmosphere of N2.
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141

I. Dez et al.
FULL PAPER
ionisation positive mode (ES+) and lockspray with phosphoric
acid, with an infusion introduction of 5 µLmin–1, a source tem-
perature of 80 °C, a desolvation temperature of 120 °C and external
calibration with NaI. X-ray data were collected at 150 K with
graphite-monochromated Mo-Kα radiation with a Bruker-Nonius
Kappa II diffractometer equipped with a CCD area detector. The
crystal structure was solved by direct methods with the SHELX97
package.[19] All non-hydrogen atoms were refined anisotropically.
All H atoms were calculated and fixed on the heavy atoms in the
ideal geometry. Hexaphenoxycyclotriphosphazene 5 was prepared
according to the method reported by Liu.[15]
HRMS: calcd. for C60H85N3O24P9 [M + H]+ 1510.3162; found
1510.3099.
Hexa(4-phosphonophenoxy)cyclotriphosphazene (4): Hexa(4-di-
ethoxyphosphorylphenoxy)cyclotriphosphazene
(3;
0.25 g,
0.16 mmol, 1 equiv.) was dissolved under an atmosphere of nitro-
gen in dichloromethane (2 mL). Bromotrimethylsilane (0.52 mL,
3.97 mmol, 24 equiv.) was added, and the solution was stirred at
room temperature for 24 h. Methanol (2 mL) was added, and the
solution was stirred at room temperature for 3 h. Solvents were
removed under reduced pressure to produce a white powder (0.19 g,
100% yield). 1H NMR (400 MHz, MeOD): δ = 7.03–7.06 (m, 2 H,
Ar-H), 7.67–7.72 (m, 2 H, Ar-H) ppm. 31P{1H} NMR (162 MHz,
MeOD): δ = 8.8 (s, 1 P, N3P3), 15.3 [s, 2 P, PO(OH)2] ppm. 13C
Diethyl 4-Hydroxyphenylphosphonate (2): A mixture of 4-bro-
mophenol (10 g, 58 mmol, 1 equiv.), nickel(II) bromide (1 g,
4.6 mmol, 0.08 equiv.) in mesitylene (10 mL) was heated at 160–
180 °C under an atmosphere of nitrogen. Triethylphosphite (14.4 g,
87 mmol, 1.5 equiv.) was added dropwise. The mixture was heated
at the same temperature and stirred under an atmosphere of nitro-
gen for the next 2 h. After cooling to room temperature, the mix-
ture was filtered through Celite, dissolved in ether and extracted
twice with a 10% solution of sodium hydroxide. The aqueous phase
was washed twice with ether, acidified by concentrated hydrochloric
acid and extracted with diethyl ether three times. The organic phase
was dried with anhydrous magnesium sulfate. Then solvent was
removed under reduced pressure to yield a colourless liquid that
crystallised at room temperature to yield a white powder (10.13 g,
3
NMR (100.62 MHz, MeOD): δ = 121.0 (d, JC,P = 15.1 Hz, C=C–
1
2
OH), 129.3 (d, JC,P = 187.0 Hz, C=C–P), 133.0 (d, JC,P
=
11.4 Hz, C=C–P), 153.0 (s, C=C–O) ppm. IR (ATR): ν = 2500–
˜
2800 and 2200–2450 (PO–H), 1593 and 1494 (C=C), 1182 (P=N),
1163 (P=O), 1128 (C–O), 970 (NP–O), 922 (P–OH). MS: m/z (%)
= 1196.4 (25) [M + Na]+, 1174.4 (20) [M + H]+, 620.7 (30), 609.7
(75), 598.7 (100), 587.7 (70). HRMS: calcd. for C36H37N3O24P9 [M
+ H]+ 1173.9406; found 1173.9401.
Crystal Data for 3: C60H84N3O24P9, M = 1510.03 gmol–1, triclinic,
¯
space group P1, a = 13.7651(7) Å, b = 15.0141(8) Å, c =
19.3629(11) Å, α = 85.735(2)°, β = 74.334(2)°, γ = 68.019(2)°, V
= 3571.4(3) Å3, Z = 2, F(000) = 1584, µ = 0.295 mm–1, Dcalcd.
=
1
1.404 Mgm–3. The 85674 reflections were collected of which 15177
were unique [R(int) = 0.0426]; 10323 reflections were observed
[IϾ2σ(I)]. The final refinement gave R1 = 0.1058 and wR2 = 0.1599
for all reflections. Goodness of fit = 1.023, residual electron density
in the final Fourier map was 1.640 and –1.818 eÅ–3. CCDC-654369
contains the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
76% yield). M.p. 98 °C. H NMR (400 MHz, CDCl3): δ = 1.31 (t,
3JH,H = 7.0 Hz, 6 H, CH3–), 4.00–4.17 (m, 4 H, –CH2–), 6.96–7.01
(m, 2 H, Ar-H), 7.59–7.68 (m, 2 H, Ar-H) ppm. 31P{1H} NMR
(162 MHz, CDCl3): δ = 20.9 (s) ppm. 13C NMR (100.6 MHz,
3
2
CDCl3): δ = 16.6 (d, JC,P = 6.6 Hz, CH3-), 62.7 (d, JC,P
=
5.3 Hz, –CH2), 116.4 (d, 3JC,P = 16.5 Hz, C=C–OH), 117.1 (d, 1JC,P
2
= 197 Hz, C=C–P), 134.2 (d, JC,P = 11.6 Hz, C=C–P), 161.9 (d,
4JC,P = 3.2 Hz, C=C–OH) ppm. IR (ATR): ν = 3300–3600 (O–H),
˜
1595 and 1494 (C=C), 1245 (P=O), 1160 (C–O), 1014 (P–O) cm–1.
MS: m/z (%) = 231.1 (100) [M + H]+, 203.0 (35), 175.0 (20).
HRMS: calcd. for C9H10NO2 [M + H]+ 231.0786; found 231.0796.
Acknowledgments
Hexa(4-diethoxyphosphorylphenoxy)cyclotriphosphazene (3):
A
mixture of hexachlorocyclotriphosphazene (1 g, 2.87 mmol,
1 equiv.), diethyl 4-hydroxyphenylphosphonate (2; 4.10 g,
17.86 mmol, 6 equiv.) and anhydrous potassium carbonate (5.72 g,
41.5 mmol, 14.4 equiv.) in acetone (80 mL) was heated at reflux for
2 h and then cooled to room temperature. The solid was filtered
and washed twice with dichloromethane. The filtrate and the wash-
ings were combined, and the solvent was removed under by reduced
pressure. The residue was dissolved in ethyl acetate and washed
with a 10% solution of sodium hydroxide two times and then once
with water and dried with anhydrous magnesium sulfate. The sol-
vent was removed under reduced pressure to obtain a colourless
liquid that crystallised at room temperature to yield a white powder
(3.51 g, 82% yield). The product was dissolved in ethyl acetate and
This work was performed within the “Réseau Matériaux Po-
lymères-Plasturgie” interregional network (Pôle Universitaire Nor-
mand). We gratefully acknowledge financial support from the
“Ministère de la Recherche et des Nouvelles Technologies”, the
CNRS (Centre National de la Recherche Scientifique), the “Région
Basse-Normandie” and the European Union (FEDER funding).
[1] a) H. R. Buser, Environ. Sci. Technol. 1986, 20, 404; b) L. S.
Birnbaum, D. F. Staskal, Environ. Health Perspect. 2004, 1, 9;
c) C. Schubert, Sci. News 2001, 160, 404; d) European directive
2003/11/EC of 6 February 2003.
[2] J. Green, J. Fire Sci. 1996, 14, 353.
[3] M. Banks, J. R. Ebdon, M. Johnson, Polymer 1994, 34, 4547.
[4] R. De Jaeger, M. Gleria, Prog. Polym. Sci. 1998, 23, 179.
[5] M. Gleria, R. De Jaeger, J. Inorg. Organomet. Polym. 2001, 11,
1–45.
recrystallised by diffusion of pentane to yield colourless crystals.
3
M.p. 50 °C. 1H NMR (400 MHz, CDCl3): δ = 1.28 (t, JH,H
=
7.0 Hz, 6 H, CH3–), 4.00–4.15 (m, 4 H, –CH2–), 7.00–7.02 (m, 2 H,
Ar-H), 7.67–7.73 (m, 2 H, Ar-H) ppm. 31P{1H} NMR (162 MHz,
CDCl3): δ = 7.5 (s, 1 P, N3P3), 17.7 [s, 2 P, PO(OEt)2] ppm. 13C
[6] J. I. Jin, U. S. Patent 74–496233, 1979, Chem. Abstr. 1979, 90,
153010m.
[7] C. M. Welch, E. J. Gonzales, J. D. Guthrie, J. Org. Chem. 1961,
26, 3270.
[8] H. R. Allcock, M. A. Hofmann, R. M. Wood, Macromolecules
2001, 34, 6915.
[9] H. R. Allcock, J. P. Taylor, Polym. Eng. Sci. 2000, 40, 1177.
[10] G. A. Carriedo, L. Fernandez-Catuxo, F. J. Garcia Alonso, P.
Gomez Elipe, P. A. Gonzalez, G. Sanchez, J. Appl. Polym. Sci.
1996, 59, 1879.
3
NMR (100.6 MHz, CDCl3): δ = 16.75 (d, JC,P = 6.2 Hz, CH3–),
2
3
62.70 (d, JC,P = 5.6 Hz, –CH2), 121.27 (d, JC,P = 14.8 Hz, C=C–
1
2
OH), 126.30 (d, JC,P = 191.1 Hz, C=C–P), 134.07 (d, JC,P
=
10.9 Hz, C=C–P), 153.70–153.71 (m, C=C–O) ppm. IR (ATR): ν
˜
= 1605 and 1510 (C=C), 1290 (P=O), 1195 (P=N), 1140 (C–O),
1007 (P–O), 956 (NP–O) cm–1. MS: m/z (%) = 1532.3 (20) [M +
Na]+, 1509.9 (2) [M + H]+, 755.6 (100), 766.6 (97), 777.6 (75).
142
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Eur. J. Inorg. Chem. 2008, 138–143

Synthesis and Properties of Phosphorylated Cyclotriphosphazenes
[11] a) L. D. Freedman, H. H. Jaffé, J. Am. Chem. Soc. 1955, 77, [17] J. Sopkova-de Oliveira Santos, D. Bauchart, C. Besset, I. Dez,
920; b) L. J. Gooßen, M. K. Dezfuli, Synlett 2005, 3, 445.
[12] P. A. Jaffrès, N. Bar, D. Villemin, J. Chem. Soc. Perkin Trans.
1 1998, 13, 2083.
[13] T. M. Balthazor, R. C. Grabiak, J. Org. Chem. 1980, 45, 5425.
[14] P. Tavs, Chem. Ber. 1970, 103, 2428.
[15] C. Ye, Z. Zhang, W. Liu, Synth. Commun. 2002, 32, 203.
[16] C. E. McKenna, M. T. Higa, N. H. Cheung, M. C. McKenna,
Tetrahedron Lett. 1977, 2, 155.
Acta Crystallogr., Sect. C 2004, 60, 751.
[18] C. E. Cullis, M. M. Hirschler, Polymer 1983, 24, 834.
[19] a) b) G. M. Sheldrick, Acta Crystallogr., Sect. A 1990, 46, 467
; G. M. Sheldrick, SHELX97: Program for the Refinement of
Crystal Structures, University of Gottingen, Germany, 1997.
Received: July 24, 2007
Published Online: November 8, 2007
Eur. J. Inorg. Chem. 2008, 138–143
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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