Halogenated hydroxy-aryloxy phosphazenes and epoxy oligomers based on them

Article abstract of DOI:10.1134/S1070427213100200

By partial substitution of the chlorine atoms in hexachlorocyclotriphosphazene for halophenols and subsequent reaction of the resulting halogenated phenoxy phosphazene and 2,2-di(4-hydroxyphenyl)propane monophenolate hydtoxy-aryloxy phosphazenes were synthesized with a molecular weight of 1100-1400 g mol-1. Epoxide oligomers (epoxy number of 6-8%), which are cured with the formation of non-combustible compositions [PV-0 class of resistance to combustion according to State Standard (GOST 28157-89)], were obtained by reaction of these compounds with epichlorohydrin. Introduction of 5-50 wt% halogenated epoxyphophazene oligomers in industrial resin ED-20 can significantly improve the fl ame resistance of compositions based on these compounds. Pleiades Publishing, Ltd., 2013.

Full text of DOI:10.1134/S1070427213100200

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 10, pp. 1600−1604. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © I.V. Terekhov, S.N. Filatov, E.M. Chistyakov, R.S. Borisov, V.V. Kireev, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86,
No. 10, pp. 1648−1652.
MACROMOLECULAR COMPOUNDS
AND POLYMERIC MATERIALS
Halogenated Hydroxy-Aryloxy Phosphazenes
and Epoxy Oligomers Based on Them
I. V. Terekhova, S. N. Filatova, E. M. Chistyakova, R. S. Borisovb, and V. V. Kireeva
Mendeleyev University of Chemical Technology, Moscow, Russia
Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, Russia
e-mail: ivan.vl.terekhov@gmail.com
Received October 2, 2013
Abstract—By partial substitution of the chlorine atoms in hexachlorocyclotriphosphazene for halophenols and
subsequent reaction of the resulting halogenated phenoxy phosphazene and 2,2-di(4-hydroxyphenyl)propane
monophenolate hydtoxy-aryloxy phosphazenes were synthesized with a molecular weight of 1100–1400 g mol–1.
Epoxide oligomers (epoxy number of 6–8%), which are cured with the formation of non-combustible compositions
[PV-0 class of resistance to combustion according to State Standard (GOST 28157-89)], were obtained by reaction
of these compounds with epichlorohydrin. Introduction of 5–50 wt% halogenated epoxyphophazene oligomers in
industrial resin ED-20 can significantly improve the flame resistance of compositions based on these compounds.
DOI: 10.1134/S1070427213100200
Oligomeric and polymeric phosphazenes and espe-
cially aryloxy phosphazenes containing various func-
tional groups in aromatic radicals are of an increasing
interest in recent years. Aryloxy phosphazenes have
proven themselves as effective modifiers of various
polymer composite materials, which improve a number
of properties of the latter, such as mechanical strength
and thermal stability [1].
In the study mixed aryloxy phosphazenes were ob-
tained containing in aromatic radicals hydroxy or epoxy
groups as well as chlorine or bromine atoms (see the
scheme).
EXPERIMENTAL
Hexachlorocyclotriphophazene was prepared by the
Aryloxycyclotriphosphazene derivatives containing reaction of phosphorous pentachloride with ammonium
chloride in chlorobenzene as described in [8]. Ethanol
(“Glavspirt”, 96%) was dried with aluminum amalgam
and distilled; epichlorohydrin (Acros, 99%), chloroben-
zene (Acros, 99%), THF (Acros, 99%), p-chlorophenol
(Vekton. 98%), p-bromophenol (Vekton, 98%), 2,2-di(4-
hydroxyphenyl)propane (Vekton, 99%), sodium hydrox-
ide anhydrous (Laverne, reagent grade) were used without
further purification.
in aromatic radical hydroxyl and epoxy groups are the
most promising [2–6]. By polycondensation of hexachlo-
rocyclotriphosphazene (HCP) with a mixture of 2,2-di(4-
hydroxyphenyl)propane mono- and diphenolates oligo-
aryloxy phosphazenes were synthesized with a molecular
weight 1500–15 000 [2], based on which methacrylate-
contaning derivatives were produced showing properties
of effective polymer modifiers of filling compositions [7].
The structures of the compounds produced were
With the use of protecting groups [3–5] hydroxyl-
containing phosphazenes were obtained, which are essen-
tially analogous to phenolformaldehyde oligomers with
improved thermal properties [5]. The epoxy derivatives
were synthesized on the basis of the same hydroxyl- ary-
loxy phosphazenes [3, 4], but these derivatives are not
widespread due to the complexity of their synthesis [1].
1
confirmed by 31P and H NMR, IR and MALDI-TOF
1
spectroscopy. 31P and H NMR spectra were recorded
in solutions of acetone-d6 or DMSO-d6 on a spectrom-
eter Bruker CXP-200 at 81 and 200 MHz, respectively,
mass spectra MALDI-TOF, on a Bruker Auto Flex II
spectrometer.
1600

HALOGENATED HYDROXY-ARYLOXY PHOSPHAZENES
1601
Scheme.
P3N3Cl6
HCP
N3P3
O
Hal
NaO
Hal
3
Cl 6-n
_NaCl
n
CH3
CH3
4
4+
NaO
OH
CH3
N3P3
O
Hal
O
OH
_NaCl
n
6-n
CH3
Oligomer of type I
O
CH3
CH3
O
NaOH,
Cl CH2 CH CH2
N3P3
O
Hal
O
O
CH2 CH CH2
_NaCl
n
6-n
Oligomer of type II
Hal = Br (oligomers Iа and IIа) or Cl (oligomers Ib and IIb), n = 2–4.
Sodium phenolates of halogenated phenols and
2,2-di(4-hydroxyphenyl)propane. In a round-necked
flask with magnetic stirrer 0.34 g (0.0086 mol) of sodium
hydroxide in 30 mL of distilled water was dissolved and
1.22 g of p-chlorophenol or 1.64 g of p-bromophenol
(0.0095 mol) was added. In the case of 2,2-di(4-hydroxy-
phenyl)propane the following loads were used: 0.46 g
(0.0115 mol) of sodium hydroxide, 30 mL of water, and
2.88 g (0.0126 mol) of 2,2-di(4-hydroxyphenyl)propane.
The reaction mixture was stirred for 1 h, afterwards water
was distilled off, and phenolates obtained were dried in
vacuo for 5 h at 70°C. Quantitative yields.
at –10°C for 2 hours for separating excess of 2,2-di(4-
hydroxyphenyl)propane and its phenolate, the mother
liquor was separated by filtration, chlorobenzene was
evaporated, the product was dried in vacuo at 80°C for
5 hours. Yield 85–87%.
1H NMR spectrum of chlorinated hydroxy-aryloxy
phosphazene (DMSO-d6), ppm: 7.40–7.20 g (a broad,
6H, aromatic ring radical chlorophenol), 6.94 g (12H,
aromatic ring radical DPP), 6.84–6.70 m (wide , 12H,
aromatic rings and DPPand chlorophenol radicals) 6.61 d
(6H, aromatic ring of DPP radical), 1.57 s (18H, CH3
group). 31P NMR (DMSO-d6), ppm: 10.08 s. Mass spectra
(MALDI-TOF), m/z: 1101, 1199.5 (major) and 1299 [M +
H] +. Brominated hydroxy-aryloxy phophazene spectra
are the same.
Compound I (see the diagram). In a 3-necked flask
equipped with magnetic stirrer, reflux condenser, ther-
mometer, and drying tube 1 g (0.00287 mol) of HCP
was dissolved in 15 mL of THF followed by dropwise
addition of a solution of sodium phenolate of the corre-
sponding halophenol (0.0086 mol) in 30 mL of THF. The
reaction mixture was stirred for 1 h at room temperature,
then the suspension of 2.87 g (0.0115 mol) of 2,2-di(4-
hydroxyphenyl)propane phenolate in 15 mL of THF was
poured into a flask and the reaction was continued at
boiling temperature a further for 12 hours. The reaction
was monitored by 31PNMR spectroscopy.Afterwards the
reaction mixture was filtered, the solvent was distilled off,
and the residue was dried in vacuo for 5 h at 60°C. The
dry residue was dissolved in chlorobenzene and frozen
Epoxide derivative [compound (II)]. In a 3-necked
flask with reflux condenser and magnetic stirrer
0.0025 mol of compound I was dissolved in 20 mL THF
and then a solution of 0.3 g (0.0075 mol) of sodium hy-
droxide in 30 mL of ethanol was poured. After 20 min-
utes to the reaction mixture 1.156 g (0.0125 mole) of
epichlorohydrin was dropwise added and stirred in the
cold for 1 h, then heated to 50°C and stirring was con-
tinued for 6 hours. Afterwards the reaction mixture was
filtered, the solvents and the residue of epichlorohydrin
were distilled in a rotary evaporator, the residue was dis-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 86 No. 10 2013

1602
TEREKHOV et al.
(a)
n
n
where
(b)
n
n
m
m
1100
1200
1300
1400
1500
1600
1700
1800
(а) MALDI-TOF mass spectra of product Iа and (b) brominated epoxy oligomer IIа. (I) Intentsity, (m/z) mass to charge
ratio.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 86 No. 10 2013

HALOGENATED HYDROXY-ARYLOXY PHOSPHAZENES
1603
solved in chloroform and washed with water until neutral
relative to litmus. The organic layer was separated, dried
over calcium chloride, and chloroform was distilled off,
the resulting product was dried in vacuo at 50°C for 5
hours. Yield 83 %.
1H NMR spectrum of chlorinated epoxy oligomer
(acetone-d6), ppm: 7.40–7.20 d (br, 6H, aromatic ring
of chlorophenol radical) 6.94 d (12H, aromatic ring of
radical DPP), 6.84–6.70 m (broad 12H, aromatic rings of
DPPand chlorophenol radicals) 6.61 d (6H, aromatic ring
of DPP radical), 4.31–3.98 d.m (6H, CH2), 3.31–3.21 m
(3H, CH), 2.82–2.60 d.m (6H, CH2 at the epoxy group),
1.57 s (18H, CH3). 31P NMR (DMSO-d6), ppm: 8.24 s.
Mass spectra (MALDI-TOF), m/z major: 1213, 1311.5,
and 1367.5 [M + H]+. The spectra of brominated oligo-
mers are similar.
contribute to lower flammability of composites based on
synthesized oligomers.
Hydroxyl-containing phosphazene were prepared ac-
cording to phenolate method: in the first step the molar
ratio of halogenated phenol phenolate to HCP= 3 : 1 was
used for preferable formation of trisubstituted derivative,
afterwards in the reaction mixture excess of diphenyl-
propane monophenolate was added and process was
conducted to reaching full replacement of the chlorine
atoms in the HCP that was evidenced by the presence of
a singlet signal at the 31P NMR spectrum of the product
obtained.
In MALDI-TOF mass spectrum of the compound Ia
(Fig. la) the basic signal corresponds to the compound
with three bromophenol and three bisphenol radicals
(n = 3). However, in the spectra there are also signals of
the products with four bromophenol and two bisphenol
radicals (n = 4), as well as with two bromophenol and four
bisphenol radicals (n = 2). MALDI-TOF mass spectrum
of the compound Ib synthesized using chlorophenol is
similar.
Oligomers containing aromatic radicals of hydroxy
group (see scheme, the oligomer I) were synthesized
by sequential substitution of the chlorine atoms in HCP
in first for residues of halogenated phenols, then for
hydroxy-aryloxy radicals. This approach allows, first, to
reduce the functionality of HCP and the probability of
formation of branched or three-dimensional structures
in further polycondensation with bisphenol; secondly, to
Synthesis of the epoxy derivatives of type II was
carried out by treating the compounds I with excess of
epichlorohydrin (ECH) in a mixture of ethanol and THF
Flame retardant compositions based on the cured resin ED-20 with additives of epoxy-phosphazene oligomers (II). Hardener
ethylenediamine, curing time 24 hours, 95% gel fraction
Content of the modifier
The burning time of the horizontally mounted The presence of burning droplets igniting
in composition, wt %
sample, s (GOST 28157-89, Method A)
cotton (GOST 28157–89, method B)
No additives
0
110
+
Additive IIа
5
63
+
–
–
15
46
50a
16
Additive IIb
5
70
55
+
–
15
50b
26
–
a Burning time of the vertically mounted sample was 21 s, and that was 55 s after the second flame application.
b Burning time of the vertically mounted sample was 29 s, and that was 67 s after the second flame application.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 86 No. 10 2013

1604
TEREKHOV et al.
as only with this way a homogeneity of reaction mixture
can be reached..
additives and with small amounts epoxyphosphazene.
However, at 15 wt% content of additives of oligomers
IIa or IIb burning droplets stop to form in a vertical test
method for resistance to combustion.As follows from the
table the bromine-containing modifier is more effective
flame retardant compared to chlorine-containing that is
consistent with literature data [9].
Apart from the most intense signal of the product IIa
with n = 3 at its MALDI-TOF mass spectrum (Fig. 1b)
there are peaks of compounds with two (n = 2, m/z = 1611)
and four bromophenoxy groups (n = 4 , m/z = 1389). Com-
pounds with less degree of addition of epichlorohydrin
with m 2, 3, or 4 are attributed by peaks m/z 1556, 1445
and 1334, respectively. MALDI-TOF mass spectra of
oligomers IIb are similar.
CONCLUSIONS
(1) Aryloxycyclotriphosphazene was synthesized with
hydroxyl groups by sequential substitution of chlorine
atoms in hexachlorocyclotripharazene for halophenol
or 2,2-di(4-hydroxyphenyl)propyl radicals. Hydroxyl-
containing aryloxy phosphazene was converted into
epoxide oligomers by the reaction with epichlorohydrin.
The epoxy numbers defined by mercurimetry method
were 6.6–6.8 (calculated 7.74%) for the compound IIa,
7.0–7.4% (calculated 9.44%) for compound IIb. This in-
dicates that on average 2.2–2.6 epoxy group fits one mol-
ecule of oligomers II. Low values of epoxy numbers are
due probably to incomplete reacting of epichlorohydrin
with hydroxyl groups. Oligomers II contain 8–16% of
halogen and 6–7% of phosphorus that a priori determines
their reduced flammability.
(2) Prooduced epoxy-phosphazene oligomers in the
course of curing form non-combustible compositions
and can be used as effective flame retardant additives to
industrial epoxy resins.
Cured by ethylenediamine oligomers IIa and IIb do
not support combustion in the case of horizontal and
vertical fixing of samples, do not form burning droplets
igniting hygroscopic surgical cotton, and are related to the
highest category of resistance to combustion PV-0 accord-
ing to GOST 28157-89, i.e., they are non-combustible.
Both types of oligomers are compatible with the indus-
trial epoxy resins ED-20, and their mixtures are cured
by ethylene diamine with the formation of 95–97% gel
fraction. The table shows the effect of different amounts
of additives of oligomers IIa and IIb to the resin ED-20
on the values of fire resistance of the cured compositions.
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