Synthesis of flame-retardant phosphaphenanthrene derivatives with high phosphorus contents

Article abstract of DOI:10.1071/CH13722

Two novel types of phosphate derivatives of phosphaphenanthrene with a high phosphorus content were prepared by phosphorylation reaction between either 2-(6-oxido-6H-dibenzc,e1,2oxaphosphorin-6-yl)-methanol (ODOPM) or 2-(6-oxido-6H-dibenzc,e1,2.oxaphosphorin-6-yl)-1,4-benzenediol (ODOPB) and dialkyl phosphoryl chloride. The structures of all compounds were characterised by ¹H NMR, ¹³C NMR, ³¹P NMR, Fourier transform infrared spectroscopy, and high-resolution mass spectrometry. The thermal stability of representative compounds was determined by thermal gravimetric analysis and differential scanning calorimetry. The results showed that the compounds have excellent resistance to oxidation, high thermal stability with an onset decomposition temperature above 200°C, and a high char yield over 25 %, owing to the high P content. The representative compound was added to conventional electrolytes of lithium-ion batteries as flame retardant additive, and the self-extinguishing time and ionic conductivity were measured. The result showed that the compounds have effective flame retardant properties.

Full text of DOI:10.1071/CH13722

CSIRO PUBLISHING
Aust. J. Chem. 2014, 67, 1688–1692
Full Paper
http://dx.doi.org/10.1071/CH13722
Synthesis of Flame-retardant Phosphaphenanthrene
Derivatives with High Phosphorus Contents
A
,
C
A
A
A
A
Jinyun Zheng,
Yujian Yu, Lulu Zhang, Xiaomin Zhen,
,
B
and Yufen Zhao
A
College of Chemistry and Molecular Engineering, Key Laboratory of Chemical Biology
and Organic Chemistry of Henan Province, Zhengzhou University, Zhengzhou
450001, P. R. China.
B
Department of Chemistry and Key Laboratory for Chemical Biology of Fujian Province,
Xiamen University, Xiamen 361005, P. R. China.
C
Corresponding author. Email: zhengjy@zzu.edu.cn
Two novel types of phosphate derivatives of phosphaphenanthrene with a high phosphorus content were prepared by
phosphorylation reaction between either 2-(6-oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-6-yl)-methanol (ODOPM)
or 2-(6-oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-6-yl)-1,4-benzenediol (ODOPB) and dialkyl phosphoryl chloride.
1
13
31
The structures of all compounds were characterised by H NMR, C NMR, P NMR, Fourier transform infrared
spectroscopy, and high-resolution mass spectrometry. The thermal stability of representative compounds was determined
by thermal gravimetric analysis and differential scanning calorimetry. The results showed that the compounds have
excellent resistance to oxidation, high thermal stability with an onset decomposition temperature above 2008C, and a high
char yield over 25 %, owing to the high P content. The representative compound was added to conventional electrolytes of
lithium-ion batteries as flame retardant additive, and the self-extinguishing time and ionic conductivity were measured.
The result showed that the compounds have effective flame retardant properties.
Manuscript received: 2 December 2013.
Manuscript accepted: 18 March 2014.
Published online: 1 May 2014.
Introduction
DOPO and its derivatives, as a class of phosphorus-contain-
ing common flame retardants, have been used in polymers such
as epoxy, polyurethanes, polyesters, and novolac resins.
Organophosphorus compounds are used to improve the fire
safety of different products such as electronic equipments,
plastic products, rubbers, textiles, and building materials. In
recent years, phosphorus-based flame retardants have become a
major source of interest because of their environmentally
friendly by-products, low toxicity, and low production of smoke
during fire. They exhibit highly effective flame retardant
properties both in the condensed phase and gas phase. Over
the past decade, several classes of organophosphorus com-
pounds have been reported as flame retardant additives such
[
12,13]
However, there are no reports on the use of DOPO derivatives as
Li-ion batteries flame retardant additives. Higher phosphorus
content means higher performance of flame retardant and lower
additive concentrations. Based on the good flame retardant
properties of DOPO and phosphates, we designed two novel
types of phosphate derivatives of DOPO with high phosphorus
contents: compound a (Scheme 1) and compound b (Scheme 2),
which were used as efficient flame retardant additive in Li-ion
batteries.
[
1]
[
2]
[3]
[4]
as phosphonates,
phosphoramidates,
oxaphosphaphenanthrene-10-oxide (DOPO).
phosphates,
cyclotriphosphazenes,
and derivatives of 9,10-dihydro-9-
[
5]
[6]
Results and Discussion
Lithium-ion batteries have been widely applied in low-power
portable electronic devices such as camcorders, cell phones, and
Synthesis and Characterisation
[
7,8]
computers,
and high-power battery packs designed for
Compounds a1–a6 were prepared by the phosphorylation
reaction between ODOPB and phosphoryl chloride. For the
phosphorylation reaction of common phenolic hydroxyl, trie-
thylamine is typically used as catalyst and acid-binding agent.
However, using triethylamine as catalyst in this study did not
generate the desired products owing to the poor solubility of
ODOPB in this reaction. Therefore, strong base potassium
carbonate was used as catalyst and acid-binding agent and the
target compounds were obtained in high yields. The structures of
electric vehicles and hybrid electric vehicles. However, con-
cerns over safety have been a key obstacle for further develop-
ment and applications of Li-ion batteries. The use of flame
retardant additives in the electrolytes is an effective method
to address this issue. Organophosphorus compounds can effec-
tively suppress flame propagation, as reported. Previous
studies have demonstrated that effective flame retardant prop-
erties can be imparted at low concentrations (i.e. ,20 %) with
minimal impact on performance.
[9,10]
[
11]
1
13
compounds a1–a6 were characterised by H NMR, C NMR,
Journal compilation Ó CSIRO 2014
www.publish.csiro.au/journals/ajc

High P-density DOPO Flame Retardants
1689
O
O
O
O
P O
(OR) PCl
O
P O
2
O
P
O
P O
H
O
P
HO
OH
CH CN/K CO
3
3
2
O
O
DOPO
ODOPB
RO
OR
Compound a
RO OR
R ϭ ϪCH , ϪCH CH , ϪCH CH CH , ϪCH(CH ) , Ϫ(CH ) CH , ϪCHCH CH CH
3
2
3
2
2
3
3 2
2 3
3
3
2
3
a1
a2
a3
a4
a5
a6
Scheme 1. Synthesis of compounds a1–a6.
O
O
P
O
PH
O
P
O
P
O
HCHO
RЈPCl, DMAP
2
RЈ
CH OH
2
O
O
CH3CN/Et3N
RЈ
O
DOPO
ODOPM
Compound b
RЈ ϭ ϪOCH , ϪOCH CH , ϪOCH CH CH , ϪC H
3
2
3
2
2
3
6
6
b1
b2
b3
b4
Scheme 2. Synthesis of compounds b1–b4.
3
1
P NMR, Fourier transform infrared spectroscopy (FTIR), and
high-resolution mass spectrometry (HRMS). The spectral data
of compounds a1–a6 were similar owing to their similar struc-
1
67
a2
a4
b4
2
65
100
100
80
60
40
20
2
09
3
1
tures. For example, the P NMR spectrum of compound a1
displayed three peaks at 17.7, ꢀ4.2, and ꢀ5.9 ppm that were
attributed to the three different chemical environments of the
phosphorus atoms. In the H NMR spectrum of a1, the signals at
4
8
6
0
0
1
.9 ppm corresponding to hydroxyl groups disappeared, and
new absorption peaks that appeared at 3.90 and 3.74 ppm with
the integral of 12H were attributed to the hydrogen atoms of the
four methoxy groups. In addition, the signals at 7.2–8.1 ppm
40
1
3
corresponded to the aromatic protons. The C NMR spectrum
of compound a1 displayed signals at 120–150 ppm corre-
sponding to different aromatic carbons and signals at 55.1 ppm
corresponding to the methoxy group. The FTIR spectrum of
20
0
100
200
300
400
500
600
700
Temperature [ЊC]
compound a1 did not show broad strong absorptions of hydroxyl
.
Fig. 1. TGA curves of compounds.
and the stretching vibration of P¼O was observed at 1150 cmꢀ
1
Compounds b1–b4 were prepared by the phosphorylation
reaction between ODOPM and phosphoryl chloride. Fewer
products were obtained when the same synthesis method as that
of compound a was used. High product yields were obtained
when triethylamine was used as catalyst and 4-dimethylamino-
pyridine (DMAP) was used as acid-binding agent. The struc-
TGA and DSC, and were due to the rigid benzene rings and high
P density. TGA curves of compounds a2, a4, and b4 measured in
nitrogen are shown in Fig. 1 and the corresponding DSC curves
are shown in Fig. 2. Fig. 1 showed that compounds a2 and a4
have similar TGA curves and both compounds displayed two
decomposition stages. The weight loss of compound a2 started
at 2658C and reached 30 % at 3008C, whereas the weight loss of
compound a4 started at 2098C and reached 26 % at 2308C. Based
on the relative molecular mass of compounds a2 and a4, the first
decomposition stage involved the decomposition of the four
alkyl chains. The main aryl structure of compound a2 started to
decompose at 3338C, with a weight loss reaching 46 % at 6288C.
However, compound a4 started to decompose at 3368C, reach-
ing a weight loss of 41 % at 6008C. The residual contents of the
compounds after decomposition at 7008C were 24 % and 32 %,
respectively. Compound b4 started to decompose at 1678C,
reaching a weight loss of 60 % at 5208C. The residual amount of
compound b4 was more than 35 % at 7008C. The DSC curves
displayed the melting points of compounds a2 and a4 that were
116–1188C and 95–978C, respectively. These values were
consistent with the data obtained from the melting point deter-
mination instrument. Additionally, Fig. 2 displayed the main
1
tures of compounds b1–b4 were characterised by H NMR,
1
3
31
C NMR, P NMR, FTIR, and HRMS. For example, the
3
1
P NMR spectrum of compound b1 displayed two peaks at
7.7 and 1.1 ppm that were attributed to the two different
2
1
phosphoryls. In the H NMR spectrum, the singlet at 3.54 ppm
corresponding to the hydroxyl group disappeared. Instead, a
double peak at 3.72 ppm with the integral of 6H belonging to the
methyl group appeared. The spectral data indicated that hydroxyl
was esterificated by phosphoryl chloride.
Thermal Gravimetric Analysis (TGA) and Differential
Scanning Calorimetry (DSC)
TGA and DSC of the compounds were conducted in nitrogen
and air, respectively. The resulting curves obtained in nitrogen
and air were comparable. The good thermal stabilities and good
resistance to oxidation of the compounds were confirmed by

1
690
J. Zheng et al.
3
2
2
0
5
0
1
18.7
0
Ϫ5
0
SET
Conductivity
2
82.8
8
9
7.3
2
13.9
Ϫ5
6
4
2
3
88.8
Ϫ10
Ϫ15
Ϫ20
Ϫ10
Ϫ15
Ϫ20
15
1
0
5
0
a2
a4
b4
0
100
200
300
400
500
600
700
0
5
10
15
20
25
Temperature [ЊC]
Compound content [wt-%]
Fig. 2. DSC curves of compounds.
Fig. 3. Relationship between the amount of flame retardant and associated
SET and ionic conductivity properties.
Table 1. Ionic conductivity and self-extinguishing time of compound a4
The ionic conductivity of the electrolytes decreased slightly
when the DOPO-based flame retardants were added, and the
ionic conductivity data are shown in Table 1. When the flame
retardants were added, the ionic conductivity of the electrolyte
decreased. With increasing additive concentrations, the conduc-
tivity decreased gradually. Fortunately, at the efficient additive
concentration of 15 %, the conductivity of the electrolyte was
Content of compound a4 [wt-%]
0
2.5
5.0
10.0 15.0 20.0 25.0
Ionic conductivity 7.50 6.82 6.32 5.50 4.96 3.90 3.25
ꢀ
1
[
mS cm ]
Self-extinguishing
time [s]
28
15
13
12
4
2
1
considerably good i.e. 4.96 ꢁ 10ꢀ S cm
3
ꢀ1
.
The relationships between the self-extinguishing time, elec-
trolyte conductivity, and flame retardant content are shown in
Fig. 3. As observed, the curves displayed an inflection point
when the additive content reached 15 %. At this additive
concentration, the sample displayed the most effective flame
retarding effect and the slowest decreasing trend in ionic
conductivity. The results indicated that the best additive con-
centration of the flame retardant is 15 %.
thermal decomposition temperatures of compounds a2, a4, and
b4 that were 283, 214, and 3898C, respectively. In summary, the
TGA and DSC results showed that both compounds a and b have
good thermal stability and high char yields owing to their rigid
structures and high P contents. Thus, they have the prerequisites
of flame retardants.
Conclusions
Two novel types of phosphate derivatives of phosphaphenan-
threne with high phosphorus contents were synthesised in high
Self-extinguishing Time
Self-extinguishing time (SET) measurements were performed
using a cotton fibre wick method in a Li-ion battery liquid
electrolyte. Different concentrations of the flame retardant
additive were ignited from a piece of cotton fibre supported on
the side of the glass cup container and the extinguishing time of
the resulting flame was determined. The self-extinguishing
times of compound a4 at different concentrations are listed in
Table 1. It can be seen that the blank electrolyte is very flam-
mable with a self-extinguishing time of 28 s. However, when the
flame-retardant material compound a4 was introduced, the
SETs of the electrolytes were significantly reduced and rapidly
decreased with increasing additive contents. Compound a4
displayed obvious flame retarding effects at 2.5 % and effective
flame retarding effects at 15 %. The SET was 4 s at 15 %. The
results showed that the phosphate derivatives of DOPO with
high phosphorus contents have good flame retarding effects in
Li-ion batteries. In addition to the TGA and DSC results, it can
be concluded that samples with a high content of phosphorus
tend to produce high amounts of char after combustion, and is
consistent with the radical stabilisation effect of organic phos-
phorus fragments. Those are expected to hinder exothermic
chain reactions and thus, lowering the temperature of the flame
and promoting char formation on the surface that cause the
samples to self-extinguish after a short period of time.
1
yields, and their structures were characterised by H NMR,
13 31
C NMR, P NMR, HRMS, and FTIR. TGA and DSC studies
showed that the compounds have good thermal stability and
good resistance to oxidation owing to their rigid structures and
high phosphorus contents. The self-extinguishing time mea-
surements showed that the compounds are efficient flame
retardant additives in Li-ion batteries at low concentrations.
This confirmed that the high-density phosphorus DOPO deri-
vatives have a high flame retardant efficiency. Studies relating
to the flame propagation, influence of the flame retardant
additives on battery performance, and associated electrochem-
ical properties are underway.
Experimental
Apparatus and Procedures
The NMR (400 MHz) spectra were obtained using a Bruker AV
400 spectrometer. Chemical shifts (d values) are given in parts
per million with tetramethylsilane as an internal standard. The
3
1
P NMR (162 MHz) spectra were referenced relative to 85 %
1
H PO (d ¼ 0 ppm) using broadband H decoupling model.
3
4
HRMS spectra were recorded on a Water Q-Tof Micro mass
spectrometer. FTIR spectra were recorded on a Bruker-Alpha
spectrometer using KBr pellets. TGA and DSC were performed

High P-density DOPO Flame Retardants
1691
on a STA 409PC thermal analyser (Germany) at a heating rate of
ꢀ
OCH ), 3.90 (q, J 8.0, 1H, OCH ), 3.57–3.75 (m, 3H, OCH ),
2
2
2
1
08C min in either nitrogen or air. The ionic conductivity data
1
1.38 (t, J 6.4, 6H, CH ), 1.05 (t, J 7.6, 6H, CH ). d (100 MHz,
3 3 C
were obtained on a Hanna EC215 conductivity tester. The
melting points were obtained using a XT4A micro melting point
determination instrument.
CDCl ) 149.5, 149.2, 146.8, 146.6, 135.6, 133.1, 130.5, 128.2,
3
126.7, 124.9, 124.5, 123.4, 120.3, 64.9, 64.6, 64.5, 16.1, 15.7. dP
(162MHz, CDCl ) 17.9, ꢀ6.4, ꢀ8.2. m/z 597.1208. HRMS Anal.
3
þ
Calc. for C H O P [M þ H] 597.1208. Found 597.1204.
2
6 32 10 3
Materials and Intermediates
[
14]
2-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
-yl)-1,4-benzenedi(di(n-propyl) phosphate)
Compound a3)
White solid (80.5 % yield), mp 123–1248C. nmax (KBr)/cm
1644, 1477 (P–Ph), 1150 (P¼O), 938 (P–O–Ph). d (400 MHz,
CDCl ) 7.96–8.08 (m, 3H, PhH), 7.60–7.73 (m, 3H, PhH), 7.53
(d, J 9.0, 1H, PhH), 7.39–7.47 (m, 2H, PhH), 7.25–7.31 (m, 2H,
PhH), 4.15 (t, J 6.3, 4H, OCH ), 3.46–3.64 (m, 4H, OCH ),
1.73–1.79 (m, 4H, CH ), 1.39–1.46 (m, 4H, CH ), 0.99 (t, J 7.2,
6H, CH ), 0.76 (t, J 6.3, 6H, CH ). d (100 MHz, CDCl ) 149.2,
DOPO was synthesised according to reference.
Dialkyl
6
(
phosphoryl chloride was prepared by the reaction between
dialkyl phosphite and sulfonyl chloride. ODOPB was prepared
by the reaction between DOPO and benzoquinone in THF, and
was purified by recrystallisation from methanol to give the pure
product, mp 255–2568C. m/z 347.0449. HRMS Anal. Calc. for
ꢀ
1
H
3
þ
C H NaO P [M þ Na] 347.0449. Found 347.0445. ODOPM
1
8
13
4
was prepared by the reaction between DOPO and formaldehyde
in THF, and was purified by recrystallisation from methanol/
petroleum to give the pure product, mp 155–1568C. m/z
2
2
2
2
3
3
C
3
þ
2
69.0344. HRMS Anal. Calc. for C H NaO P [M þ Na]
146.7, 135.5, 133.1, 130.5, 130.4, 130.4, 128.3, 128.1, 126.6,
126.5, 124.9, 124.5, 123.4, 123.3, 121.4, 121.3, 120.3, 70.2,
1
3
11
3
2
69.0344. Found 269.0348. Benzoquinone, o-phenylphenol,
formaldehyde, sulfonyl chloride, THF, acetonitrile, triethyla-
mine, potassium carbonate, 4-dimethylaminopyridine and other
reagents were used as supplied.
23.5, 9.9. d
HRMS Anal. Calc. for C30
P
(162 MHz, CDCl
H
40
653.1868. Anal. Calc. for C30
3
) 17.9, ꢀ6.3, ꢀ8.0. m/z 653.1834.
þ
O
P
3
[M þ H] 653.1834. Found
10
þ
H
39NaO10
P
[M þ Na] 675.1654.
3
Found 675.1652.
Synthesis of Compounds a1–a6
2
6
-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
-yl)-1,4-benzenedi(diisopropyl phosphate)
Compounds a1–a6 were prepared by the reaction between
ODOPB and dialkyl phosphoryl chloride using a similar pro-
cess. The synthesis of product a4 is exemplified: ODOPB
(
Compound a4)
White solid (93 % yield), mp 91–928C. nmax (KBr)/cm
101, 2985, 1598, 1475 (P–Ph), 1277, 1209, 1145 (P¼O), 1017,
39 (P–O–Ph), 759. d (400 MHz, CDCl ) 7.99–8.06 (m, 2H,
ꢀ
1
(10.00 g, 0.03 mol), K CO (4.80 g, 0.035 mol), and anhydrous
CH CN (500 mL) were placed in a 1-L three-neck flask. After
2 3
3
9
3
the suspension became clear at a raised temperature, diisopropyl
phosphoryl chloride (14.00 g, 0.07 mol) in 50 mL CH CN
H
3
PhH), 7.91 (d, J 15.4, 1H, PhH), 7.60–7.70 (m, 3H, PhH), 7.50
d, J 9.0, 1H, PhH), 7.36–7.45 (m, 2H, PhH), 7.23–7.28 (m, 2H,
PhH), 4.71–4.80 (m, 2H, OCH), 4.40–4.48 (m, 1H, OCH), 4.22–
.30 (m, 1H, OCH), 1.11 (d, J 6.2, 3H, CH ), 1.05 (d, J 6.2, 3H,
3
(
was added dropwise to the solution over 2 h. The reaction
solution was refluxed for 6 h. An insoluble solid was isolated
from the hot solution by filtration. The filtrate was cooled and a
white solid was obtained. The solid was then retrieved by fil-
tration, washed with dichloromethane, dried, and recrystallised
from dichloromethane/petroleum. The pure compound a4 was
obtained as a white solid (18.71 g, 93 %), mp 91–928C.
4
3
CH ), 0.98 (d, J 6.1, 6H, CH ), 0.87 (d, J 6.8, 12H, CH ). d
C
3
3
3
(
1
2
100 MHz, CDCl ) 149.5, 149.2, 146.9, 146.7, 135.6, 133.0,
3
30.4, 128.1, 126.5, 124.9, 123.4, 121.7, 120.4, 73.9, 73.7, 23.5,
3.3, 23.1. dP (162 MHz, CDCl ) 18.5, ꢀ8.2, ꢀ9.7. m/z
3
þ
6
675.1654. Found 675.1645.
75.1654. HRMS Anal. Calc. for C H NaO P Na [M þ Na]
3
0
39
10 3
Characterisation Data of Compounds a1–a6
2
-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-6-
2
6
-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
-yl)-1,4-benzenedi(di(n-butyl) phosphate)
yl)-1,4-benzenedi(dimethyl phosphate) (Compound a1)
ꢀ
1
White solid (78.0 % yield), mp 104–1058C. nmax (KBr)/cm
1649, 1478 (P–Ph), 1148 (P¼O), 940 (P–O–Ph). d (400 MHz,
CDCl ) 8.04–8.11 (m, 2H, PhH), 7.94 (d, J 14.9, 1H, PhH), 7.72
(Compound a5)
H
ꢀ1
White solid (89.2 % yield), mp 158–1598C. nmax (KBr)/cm
1640, 1478 (P–Ph), 1147 (P¼O), 935 (P–O–Ph). d (400 MHz,
CDCl ) 7.96–8.08 (m, 3H, PhH), 7.59–7.72 (m, 3H, PhH), 7.52
(d, J 9.6, 1H, PhH), 7.38–7.46 (m, 2H, PhH), 7.25–7.31 (m, 2H,
PhH), 4.17 (q, J 6.7, 4H, OCH ), 3.58–3.76 (m, J 7.2, 4H,
OCH ), 1.68–1.76 (m, 8H, CH ), 1.33–1.45 (m, 8H, CH ), 0.88
2
(t, J 7.3, 12H, CH ). d (100 MHz, CDCl ) 149.3, 146.9, 135.6,
133.0, 130. 6, 130.4, 128.3, 128.2, 126.8, 126.6, 125.2, 124.9,
24.5, 123.4, 123.3, 121.5, 121.4, 120.4, 68.5, 32.1, 18.6, 13.5.
(162 MHz, CDCl
3
H
(
q, J 7.5, 2H, PhH), 7.58 (t, J 7.7, 1H, PhH), 7.49 (d, J 8.5, 2H,
3
PhH), 7.41 (t, J 7.7, 1H, PhH), 7.28–7.32 (m, 2H, PhH), 3.90 (q,
J 6.0, 6H, OCH ), 3.74 (q, J 6.7, 6H, OCH ). d (100 MHz,
CDCl ) 149.4, 146.7, 135.6, 133.3, 130.8, 130.7, 130.6, 128.4,
3
3
C
2
3
2
2
1
1
28.3, 126.7, 126.3, 124.9, 124.6, 123.4, 123.3, 121.3, 121.2,
20.4, 55.2, 55.1, 54.7. d (162 MHz, CDCl ) 17.7, ꢀ4.2, ꢀ5.9.
3 C 3
P
3
þ
m/z 541.0585. HRMS Anal. Calc. for C H O P [M þ H]
2
2 24 10 3
1
5
[
41.0582. Found 541.0585. Anal. Calc. for C H O P Na
22 23 10 3
þ
d
P
3
) 17.9, ꢀ6.2, ꢀ7.9. m/z 709.2460. HRMS
M þ Na] 563.0402. Found 563.0407.
þ
Anal. Calc. for C H O P [M þ H] 709.2460. Found
3
4 48 10 3
þ
7
Found 731.2273.
09.2499. Anal. Calc. for C H O P [M þ Na] 731.2280.
3
4 47 10 3
2
6
-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
-yl)-1,4-benzenedi(diethyl phosphate) (Compound a2)
ꢀ
1
2-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
-yl)-1,4-benzenedi(di(sec-butyl) phosphate)
Compound a6)
White solid (76.2 % yield), mp 208–2098C. nmax (KBr)/cm
1643, 1479 (P–Ph), 1147 (P¼O), 941 (P–O–Ph). d (400 MHz,
White solid (82.6 % yield), mp 112–1138C. nmax (KBr)/cm
6
(
1650, 1479 (P–Ph), 1146 (P¼O), 942 (P–O–Ph). d (400 MHz,
CDCl ) 8.01–8.08 (m, 2H, PhH), 7.94 (d, J 15.0, 1H, PhH),
.58–7.71 (m, 3H, PhH), 7.37–7.50 (m, 3H, PhH), 7.24–7.29
m, 2H, PhH), 4.24 (q, J 7.1, 3H, OCH ), 4.13 (q, J 7.2, 1H,
H
3
ꢀ1
7
(
2
H

1
692
J. Zheng et al.
CDCl ) 7.92–8.05 (m, 3H, PhH), 7.60–7.69 (m, 3H, PhH), 7.54
3
7.90–8.03 (m, 3H, PhH), 7.68–7.75 (m, 1H, PhH), 7.33–7.56
(m, 3H, PhH), 7.20–7.25 (m, 1H, PhH), 4.49–4.65 (m, 2H, CH O),
(
s, 1H, PhH), 7.35–7.41 (m, 2H, PhH), 7.22–7.27 (m, 2H, PhH),
.52–4.62 (m, 3H, OCH), 4.25–4.27 (m, 1H, OCH), 1.61–1.72
m, 8H, CH ), 1.26–1.37 (m, 12H, CH ), 0.91–0.97 (m, 12H,
2
4
4.05–4.17 (m, 4H, OCH ), 1.42–1.50 (m, 4H, CH ), 0.75–0.79
2
2
(
(m, 6H, CH ). d (100 MHz, CDCl ) 149.6, 136.7, 134.2, 131.1,
3 C 3
2
3
CH ). d (100 MHz, CDCl ) 149.3, 146.8, 135.6, 132.9, 130.5,
3
130.8, 128.6, 128.3, 124.8, 123.4, 123.5, 121.2, 120.1, 63.8, 54.2,
3
C
1
1
30.4, 130.2, 128.2, 128.0, 126.5, 126.4, 124.8, 124.4, 123.8,
23.4, 121.7, 121.5, 120.5, 78.5, 30.1, 20.8, 9.2. d (162 MHz,
54.1, 23.5, 9.7. d (162 MHz, CDCl ) 28.4, ꢀ1.3. m/z 411.1126.
P
3
þ
HRMS Anal. Calc. for C H O P [M þ H] 411.1126. Found
þ
19 24 6 2
P
19 25 6 2
CDCl ) 18.4, ꢀ7.6, ꢀ8.9. m/z 709.2460. HRMS Anal. Calc. for
411.1123. Anal. Calc. for C H NaO P [M þ Na] 433.0946.
3
þ
C H O P [M þ H] 709.2460. Found 709.2458. Anal. Calc.
Found 433.0941.
3
4 48 10 3
þ
for C H O P [M þ Na] 731.2280. Found 731.2324.
3
4 47 10 3
2-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
Synthesis of Compounds b1–b4
6-yl)-methene-diphenyl phosphate (Compound b4)
ꢀ
1
Compounds b1–b4 were prepared by the reaction between
ODOPM and dialkyl phosphoryl chloride using a similar pro-
cess. The synthesis of product b1 is exemplified: ODOPM
White solid (84.1 % yield), mp 120–1218C. nmax (KBr)/cm
1648, 1463, 1161 (P¼O), 941 (P–O–Ph). d (400 MHz, CDCl )
H
3
7.91–8.04 (m, 3H, PhH), 7.69–7.81 (m, 3H, PhH), 7.35–7.60
(m, 7H, PhH), 7.17–7.33 (m, 5H, PhH), 5.19 (s, 2H, CH O). d
C
(1.00 g, 4.06 mmol) and anhydrous CH CN (30 mL) were
3
2
placed in a 50-mL three-neck flask. The mixture was heated to
08C and became clear. Then the solution was cooled to room
temperature. Next, triethylamine (0.64 mL, 4.62 mmol) and
-dimethylamiopyridine (0.0376 g, 0.0308 mmol) were placed
(100 MHz, CDCl ) 150.1, 149.5, 136.8, 135.5, 134.2, 132.6,
3
7
131.8, 131.4, 131.3, 131.2, 130.8, 130.7, 130.5, 129.0, 128.9,
128.1, 127.9, 125.1, 124.9, 123.7, 123.5, 122.2, 121.9, 120.2,
60.4. d (162 MHz, CDCl ) 35.0, 29.1. m/z 447.0915. HRMS
4
P
3
þ
in the flask. The diethyl phosphoryl chloride (0.65 g, 4.64 mmol)
in 3 mL CH CN was added dropwise to the solution over 30 min.
Anal. Calc. for C H O P [M þ H] 447.0915. Found
þ
25 20 6 2
2
5 21 6 2
3
447.0910. Anal. Calc. for C H NaO P [M þ Na] 469.0735.
The reaction solution was refluxed for 3 h. Following comple-
tion of the reaction, the solution was distilled under reduced
pressure. The crude product was obtained and recrystallised
from ethyl acetate/petroleum. The pure compound b1 was
obtained as a white solid (1.2 g, 88.2 %), mp 112–1138C.
Found 469.0729.
Supplementary Material
The spectra of the compounds, and the TGA and DSC curves in
air are available on the Journal’s website.
Characterisation Data of Compounds b1–b4
Acknowledgement
2
6
-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
-yl)-methene-dimethyl phosphate (Compound b1)
The authors thank the National Natural Science Foundation Committee of
China for financial support (No. 20972130).
ꢀ1
White solid (69.2 % yield), mp 76–778C. nmax (KBr)/cm
1
7
1
4
4
1
5
639, 1479, 1152 (P¼O), 936 (P–O–Ph). d (400 MHz, CDCl )
H
3
References
.94–8.06 (m, 3H, PhH), 7.72–7.79 (m, 1H, PhH), 7.54–7.59 (m,
H, PhH), 7.39 (t, J 7.5, 1H, PhH), 7.25–7.29 (m, 2H, PhH),
[
1] S. Y. Lu, I. Hamerton, Prog. Polym. Sci. 2002, 27, 1661. doi:10.1016/
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[2] M. Garc ´ı a, I. Rodr ´ı guez, R. Cela, J. Chromatogr. A 2007, 1152, 280.
doi:10.1016/J.CHROMA.2006.11.046
[3] S. Liang, M. Neisius, H. Mispreuve, R. Naescher, S. Gaan,
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MDEGRADSTAB.2012.07.019
[4] Q. Zhang, H. Noguchi, H. Wang, M. Yoshio, M. Otsuki, T. Ogino,
Chem. Lett. 2005, 34, 1012. doi:10.1246/CL.2005.1012
.53–4.63 (m, 1H, CH O), 4.17–4.32 (m, 1H, CH O), 3.72 (d, J
2
2
.0, 6H, OCH ). d (100 MHz, CDCl ) 149.4, 136.6, 134.4,
3
3
C
31.1, 130.8, 128.8, 128.3, 124.7, 123.7, 123.4, 121.1, 120.2,
4.6, 54.1. dP (162 MHz, CDCl ) 27.7, 1.1. m/z 355.0500.
3
þ
HRMS Anal. Calc. for C H O P [M þ H] 355.0500. Found
1
5 17 6 2
þ
3
Found 377.0316.
55.0497. Anal. Calc. for C H NaO P [M þ Na] 377.0320.
1
5
16
6 2
[
5] M. J. Tsafack, J. Levalois-Gr u¨ tzmache, Surf. Coat. Tech. 2006, 201,
599. doi:10.1016/J.SURFCOAT.2006.05.002
2
2
6
-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
-yl)-methene-diethyl phosphate (Compound b2)
[
6] A. K o¨ nig, E. Kroke, Fire Mater. 2012, 36, 1. doi:10.1002/FAM.1077
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35104644
[
ꢀ1
White solid (88.2 % yield), mp 83–848C. nmax (KBr)/cm
1
7
1
4
649, 1487, 1154 (P¼O), 931 (P–O–Ph). d (400 MHz, CDCl )
[8] M. Broussely, G. Archdele, J. Power Sources 2004, 136, 386.
H
3
doi:10.1016/J.JPOWSOUR.2004.03.031
.95–8.07 (m, 3H, PhH), 7.72–7.80 (m, 1H, PhH), 7.54–7.60 (m,
H, PhH), 7.42 (t, J 7.4, 1H, PhH), 7.26–7.31 (m, 2H, PhH),
.54–4.63 (m, 2H, CH O), 4.10–4.18 (m, 2H, OCH ), 3.86–3.94
[
9] E. G. Shim, T. H. Nam, J. G. Kim, H. S. Kim, S. I. Moon, Electrochim.
Acta 2009, 54, 2276. doi:10.1016/J.ELECTACTA.2008.10.037
2
2
[
10] H. F. Xiang, H. Y. Xu, Z. Z. Wang, C. H. Chen, J. Power Sources 2007,
73, 562. doi:10.1016/J.JPOWSOUR.2007.05.001
(m, 2H, OCH ), 1.19 (t, J 7.0, 3H, CH ), 1.14 (t, J 7.0, 3H, CH ).
d (100 MHz, CDCl ) 149.5, 136.7, 134.3, 131.1, 130.8, 128.7,
1
2 3 3
1
C
3
[
11] K. Xu, S. S. Zhang, J. L. Allen, J. Electrochem. Soc. 2002, 149, A1079.
28.2, 124.6, 123.5, 123.2, 121.2, 120.2, 64.4, 63.5, 15.9. dP
doi:10.1149/1.1490356
(
162 MHz, CDCl ) 28.0, ꢀ1.4. m/z 383.0810. HRMS Anal.
3
[12] X. Wang, L. Song, W. Xing, H. Lu, Y. Hu, Mater. Chem. Phys. 2011,
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PAT.1728
þ
Calc. for C H O P [M þ H] 383.0810. Found 383.0813.
1
7 21 6 2
þ
Anal. Calc. for C H NaO P [M þ Na] 405.0633. Found
1
7
20
6 2
4
05.0628.
[
14] C. S. Wang, J. Y. Shieh, Polymer 1998, 39, 5819. doi:10.1016/S0032-
861(97)10292-0
3
2
6
-(6-Oxido-6H-dibenz,c,e.,1,2.oxaphosphorin-
-yl)-methene-dipropyl phosphate (Compound b3)
ꢀ1
White solid (76.3 % yield), mp 94–958C. nmax (KBr)/cm
647, 1479, 1156 (P¼O), 933 (P–O–Ph). d (400 MHz, CDCl )
1
H
3