Synthesis of new dibenzo[c.e][1,2]oxaphosphorine 2-oxide containing diols based on diethanolamine

Article abstract of DOI:10.1002/hc.20763

Different approaches were applied to obtain new diol compounds based on dibenzo[c.e][1,2]oxaphosphorine 2-oxide (DOPO, 1) and diethanolamine (DEolA). Of four processes investigated, a four-step synthesis of 1 containing propionic acid amide of DEolA proved to be the most efficient one. In addition, the intramolecular amine salt of the DOPO derivative with a ring-opened structure was obtained by reinvestigation of the reaction of DOPO with DEolA and paraformaldehyde. The Atherton-Todd reaction of 1 and DEolA was investigated as well.

Full text of DOI:10.1002/hc.20763

Heteroatom Chemistry
Volume 23, Number 2, 2012
Synthesis of New
Dibenzo[c.e][1,2]oxaphosphorine 2-oxide
Containing Diols Based on Diethanolamine
Yana Bykov,1 Sebastian Wagner,1 Olaf Walter,1 Manfred Do¨ring,1
Oliver Fischer,2 Doris Pospiech,2 Thomas Ko¨ppl,3 and Volker
Altsta¨dt3
1Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology,
Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
2Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, 01069 Dresden, Germany
3Department of Polymer Engineering, University of Bayreuth, Universita¨tsstr.
30, 95447 Bayreuth, Germany
Received 3 May 2011; revised 21 August 2011
INTRODUCTION
ABSTRACT: Different approaches were ap-
Commercially available dibenzo[c.e][1,2] oxaphos-
phorine 2-oxide (DOPO, 1) and its derivatives are
applied as ligands in coordination chemistry [1]
and, additionally, they are known to be versatile
and environmentally friendly substances used to ren-
der a broad range of polymers flame retardant [2–
4]. They can be incorporated into the polymer ma-
trix as either nonreactive additives [5–7] or reactive
comonomers [8–10]. For a long time, the synthesis of
such functionalized DOPO derivatives and the study
of their flame-retardant properties have been of great
interest to both industry and academia [11,12]. The
synthesis of DOPO-containing molecules with alco-
hol functionalities is especially attractive for chemi-
cal connection of 1 with the polymer backbone, for
example, as comonomers in polyesters [13–15] or
polyurethanes [16].
plied to obtain new diol compounds based on
dibenzo[c.e][1,2]oxaphosphorine 2-oxide (DOPO,
1) and diethanolamine (DEolA). Of four processes
investigated, a four-step synthesis of 1 containing
propionic acid amide of DEolA proved to be the
most efficient one. In addition, the intramolecular
amine salt of the DOPO derivative with a ring-opened
structure was obtained by reinvestigation of the
reaction of DOPO with DEolA and paraformaldehyde.
The Atherton–Todd reaction of 1 and DEolA was
ꢀ
C
investigated as well.
2011 Wiley Periodicals, Inc.
Heteroatom Chem 23:146–153, 2012; View this article
online at wileyonlinelibrary.com. DOI 10.1002/hc.20763
This article will present the synthesis of novel di-
ethanolamine (DEolA) derivatives possessing one or
more DOPO units. Such compounds are expected to
benefit from a phosphorus–nitrogen synergism sup-
porting their flame retardancy. This was already re-
ported for other phosphorus–nitrogen systems, for
example, flame retardants for cellulose [17]. The
Correspondence to: Yana Bykov; e-mail: yana.bykov@kit.edu,
Manfred Do¨ring; e-mail: manfred.doering@kit.edu.
Contract grant sponsor: German Research Foundation (DFG).
Contract grant number: DO 453/7-1.
c
ꢀ
2011 Wiley Periodicals, Inc.
146

Synthesis of New Dibenzo[c.e][1,2]oxaphosphorine 2-oxide Containing Diols Based on Diethanolamine 147
synthesis of DOPO derivatives containing nitrogen
was decided to connect DOPO and DEolA directly as
an alternative approach.
functionalities is of interest since synergistic systems
often allow for a reduced flame-retardant load while
maintaining high efficiency.
Three alternative approaches for achieving the
goal of connecting 1 and DEolA were investi-
gated and compared. The first strategy was a
Kabachnik–Fields reaction, the second approach
was an Atherton–Todd reaction, and the third one
was the synthesis of DOPO containing propionic
acid amide of DEolA.
In an attempt to synthesize new OH-
functionalized DOPO derivatives, the Atherton–
Todd reaction was taken, a reaction known to be
an effective way for the synthesis of phosphorami-
dates from phosphorus compounds containing re-
active P H bonds, such as phosphites and phos-
phonites [21,22]. Recently, the synthesis of new
phosphoramidates with ethanolamine and bis(2-
hydroxyethyl)amine using the Atherton–Todd ap-
proach was reported in the literature [23,24]. The
results presented suggest a selective reactivity of
primary as well as secondary amines in the pres-
ence of primary alcohols in this reaction. However,
such selectivity was not observed in our work. The
synthesis of DOPO–DEolA (6) using the Atherton–
Todd reaction according to Scheme 2 yielded a
mixture of different products. Moreover, 31P NMR
spectroscopy (signals at 11–12 ppm related to the
DOPO-O compounds vs. signals at 16–17 ppm re-
lated to the DOPO-N compounds in CDCl3) demon-
strates that most of these compounds resulted from
the reaction of hydroxyl groups of DEolA with 1.
This can be explained by the fact that the selectivity
is strongly dependent on the nature of the phospho-
rus atom and its reactivity.
RESULTS AND DISCUSSION
The connection of 1 to DEolA through a methy-
lene group by a Kabachnik–Fields approach was
described in a US patent in 1988 [18]. The au-
thors report that the reaction between 1 and DE-
olA with paraformaldehyde in water as a solvent
yields a “material, which is very viscous, colorless,
and transparent” (2) (Scheme 1). However, when re-
peating the synthesis in accordance with the pub-
lished procedure, a white precipitate was obtained
by concentration of the reaction mixture in vacuum.
1
Spectroscopic data, namely, H NMR (a broad sig-
nal at 10.9 ppm in DMSO) and ESI MS (a peak
[M – H]− at m/z = 350 in the negative measurement)
revealed the formation of an intramolecular amine
salt of ring-opened DOPO (3) via hydrolysis of 2. A
similar phenomenon was observed by Keglevich et
al. during a study of the Kabachnik–Fields reaction
of 1 under microwave conditions [19]. Moreover,
the intermolecular amine salt 4 was obtained by
the stirring of 6H-dibenz[c, e][1,2]oxaphosphorin-
6-propanoic acid methyl ester 6-oxide (DOPAcMe,
5; synthesized by the Michael-like addition of 1 to
methyl acrylate in the presence of triethylamine [20])
with diethylamine under air (Scheme 2). This con-
firms that 1 easily hydrolyzes in the presence of a
base to yield a ring-opened salt. The structures of 3
and 4 were confirmed by X-ray diffraction (XRD) of
single crystals (Fig. 1).
To reverse the hydrolysis reaction, substance 3
was heated to 120◦C in vacuum and, indeed, the
formation of the target molecule 2 was observed
(Scheme 1). However, partial decomposition occurs
under these conditions, which is reflected by the ap-
pearance of additional signals in the 31P NMR and
1H NMR spectra.
Using 3 equiv of 1 in the same reaction caused a
complete conversion of DEolA, yielding compound
7 with all three functionalities of DEolA connected
to a DOPO unit (Scheme 3).
Although the selective amination of 1 with
DEolA via the Atherton–Todd reaction was not suc-
cessful, the synthesis of an alternative molecule was
investigated. The aim was to access the DOPO-
containing propionic acid amide of DEolA (8).
Aminolysis of DOPAcMe (5) was performed un-
der an inert atmosphere without any solvent using
ammonium hydrochloride as a catalyst (Scheme 4,
reaction I). The desired compound 8 was obtained in
good yields. However, side products were present in
the reaction mixture. 31P NMR spectroscopy (signals
at 37 ppm in CDCl3) suggests that a partial transes-
terification with the hydroxyl groups of DEolA and
DOPO took place. The resulting compounds are pre-
sented in Fig. 2. Unfortunately, separation of these
compounds was not possible.
Another path to access DOPAcDEolA (8) is a two-
step synthesis shown in Scheme 4 (route II). For
this purpose, N,N-bis(2-hydroxyethyl)acrylamide
(AcDEolA, 9) has to be obtained (Scheme 4, reac-
tion IIa). In the following step, 1 is to react with 9
in a Michael-type reaction [25,26] and to ultimately
yield the desired molecule 8 (Scheme 4, reaction IIb).
The intermediate AcDEolA (9) can be synthesized in
Even though the described synthesis was not re-
producible [18] and prevention of the ring opening
was reported to be unsuccessful [19], we were still
able to obtain the target molecule 2. Nonetheless,
the synthesis of 2 remains inefficient. Therefore, it
Heteroatom Chemistry DOI 10.1002/hc

148 Bykov et al.
OH
OH
HN
O
P
O
P
OH
P
OH
OH
H O
2
OH
OH
H
O
N
NH
(CH O)n
Δ
2
2
H O
O
O
O
3
2
DOPO 1
SCHEME 1 Synthesis of compounds 2 and 3.
O
O
O
OH
O
P
DOPO1
H O (air)
2
+ HN
NEt
O
3
O
O
P
O
O
O
H N
2
DOPAcMe 5
4
SCHEME 2 Synthesis of compounds 4 and 5.
FIGURE 1 Molecular structures of compounds 3 and 4 validated by X-ray analysis.
OH
OH
O
N
P
O
DOPO – DEolA
1:1
6
CCl4,
NEt3
DOPO 1 + DEolA
dry CHCl3
DOPO – DEolA
3:1
P
N
O
O
O
O
P
P
O
O
O
O
7
SCHEME 3 Atherton–Todd reaction of DOPO (1) with DEolA.
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of New Dibenzo[c.e][1,2]oxaphosphorine 2-oxide Containing Diols Based on Diethanolamine 149
OH
OH
O
OH
OH
O
OH
OH
O
O
P
DOPO 1
Cl
HN
N
IIb
IIa
N
O
DEolA
DOPAcDEolA 8
AcDEolA 9
IIIc
IVd
CH3OH
CH3COOH
IIIa
IVa
O
O
O
Si
Si
HN
Si
OH
OH
O
I
HN
N
P
O
Si
12
Si(Me)3
O
HN
O
IVc
DOPO 1
Si(Me)3
O
10
IIIb
O
O
Si
O
O
Si
O
O
P
Cl
HN
N
O
IVb
O
Si
O
Si
11
10
DOPAcMe 5
SCHEME 4 Synthesis of DOPAcDEolA (8). I: DEolA, NH4Cl, 120◦C. IIa: (a) AcCl, NEt3, CH2Cl2, 5◦C; (b) Na2CO3, MeOH,
H2O, r.t. IIb: DOPO, NEt3, dry toluene, reflux. IIIa (IVa): hexamethyldisilazane, reflux. IIIb: 10, NH4Cl, dry toluene, reflux. IIIc
(IVd): CH3OH, CH3COOH, reflux. IVb: AcCl, NEt3, dry n-pentane, 5◦C; IVc: DOPO, NEt3, dry toluene, reflux.
Coming back to the idea of the aminolysis of
DOPAcMe (5) with DEolA, it was decided to mask
the hydroxyl functionalities of the latter with pro-
NR2
O
O
R1, R2, R3 = H or
tection groups to prevent the transesterification re-
action. Applying a synthesis described in the litera-
ture [28], we were able to solely protect the hydroxyl
groups of DEolA with hexamethyldisilizane, leaving
the secondary amine unaffected and yielding the de-
sired product 10 (Scheme 4, reaction IIIa). Aminol-
ysis of 10 with DOPAcMe (5) (Scheme 4, reaction
IIIb) reached 50% conversion after only 24 h.
P
R1O
OR3
O
FIGURE 2 Possible products in the reaction of DOPAcMe
with DEolA (Scheme 4, reaction I).
Finally, route IV in Scheme 4 demonstrates
the most efficient way to obtain the desired prod-
uct DOPAcDEolA (8). The synthesis includes four
steps. After protection of DEolA with trimethylsi-
lyl groups [28] (Scheme 4, reaction IVa), followed
a nucleophilic substitution of acryloyl chloride with
10 (Scheme 4, reaction IVb); the product (11) was
obtained at a yield of 92%. The Michael-like ad-
dition of 1 to the double bond of compound 11
was carried out according to the synthesis described
for DOPAcMe (5), using triethylamine as a catalyst
(Scheme 4, reaction IVc). The trimethylsilyl groups
are very sensitive to air and moisture, which is why
two steps: reaction of DEolA with 3 equiv of acryloyl
chloride followed by a selective hydrolysis of the hy-
droxyl groups using sodium carbonate [27]. The de-
scribed method was slightly modified, and AcDEolA
(9) was synthesized successfully. However, complete
polymerization of this very reactive substance oc-
curs during a few hours at room temperature. This,
in turn, means that it is not possible to apply AcDE-
olA (9) in a Michael-type addition without obtaining
polymers as side products. The use of stabilization
agents was not desirable because of the problematic
separation and purification of the final product.
Heteroatom Chemistry DOI 10.1002/hc

150 Bykov et al.
the analytical data of 12 tend to reveal traces of the
hydrolyzed compound. Total deprotection of the hy-
droxyl groups occurred very smoothly by reflux in
methanol in the presence of acetic acid (Scheme 4,
reaction IVd). DOPAcDEolA (8) was obtained in a
quantitative yield. For compound 8, the 13C NMR sig-
nals of C O, C O, and C N were doubled, and in the
1H NMR spectrum, all methylene groups appeared
as multiplets. This fact can be explained by the for-
mation of hydrogen bonds and by a partial double
bond character of the amidic C N bond, which re-
stricts the rotation around the C N axis. The struc-
ture and purity of DOPAcDEolA (8) were addition-
ally confirmed by HR-MS and elemental analysis,
respectively.
To summarize our results, the intramolecular
amine salt of the DOPO derivative with an opened
ring (3) was described. It was formed by the addition
of water to compound 2 in the presence of a base.
The reverse ring-closing reaction was also demon-
strated. It was shown that the addition of 1 to the
amine group of DEolA using the Atherton–Todd re-
action is not selective because of the similar reactiv-
ities of all three functional groups of DEolA and the
very reactive phosphorus center. On the other hand,
substance 7, containing three DOPO units, was suc-
cessfully synthesized using 3 equiv of 1. Finally, the
synthesis of the new DOPO compound containing a
diol functionality (8) was developed and described.
Of the four approaches investigated, one was found
to be the most efficient. All four steps of this route
provide the corresponding products 10, 11, 12,
and 8 at very high yields. This successful synthesis
demonstrates a novel pathway to OH-functionalized
phosphorus-containing compounds that can be in-
corporated as reactive flame retardants in the
polymers.
High-resolution mass spectrometry (HR MS) analy-
ses were performed on a MicroMass GCT (time of
flight (TOF); electron ionization (EI), 70 eV) and
Bruker micrOTOF (Nano ESI Offline). IR spectra
were recorded with a Varian 660-IR (FT-IR).
Crystallographic Data
XRD measurements were performed using
a
Siemens SMART CCD 1000 diffractometer with
monochromated Mo Kα-irradiation collecting a full
sphere of data in the θ ranging from 1.57 to 28.34◦.
Frames were collected with an irradiation time of
20 s (3) or 10 s (4) per frame and using the ω-scan
technique with ꢀω = 0.45◦. Data were corrected to
Lorentz and polarization effects, and an empirical
adsorption correction with SADABS [29] was ap-
plied. The structures were solved by direct methods
and refined to an optimum R1 value with SHELX-
97 [30]. Visualization for evaluation was performed
with xpma [31], and figures were created with OR-
TEP [32].
Cambridge Crystallographic Data Centre
(CCDC) numbers 811746 and 811747 contain the
supplementary crystallographic data for this paper.
These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from
the Cambridge Crystallographic Data Centre, 12,
Union Road, Cambridge CB2 1EZ, UK; fax: + 44
1223 336033; or deposit@ccdc.cam.ac.uk).
((Bis(2-hydroxyethyl)ammonio)methyl)(2ꢁ -hydr-
oxy-[1,1ꢁ-biphenyl]-2-yl)phosphinate (3)
DOPO (1) (20.0 g, 92.0 mmol) and DEolA (9.7 g,
92.0 mmol) were dissolved in 40 mL of distilled wa-
ter in a three-neck flask equipped with a reflux con-
denser, a thermometer, and an addition funnel. The
reaction mixture was heated to 80◦C using an oil
bath, and paraformaldehyde (3.10 g) was added in
a dropwise manner during a period of 5 min. The
reaction mixture was refluxed for 1 h, cooled down
to room temperature, and then concentrated in vac-
uum using a rotary evaporator to yield a white pre-
cipitate. After filtration, followed by washing with
distilled water and drying in air, the product 3 was
obtained as a white solid (15.2 g, 43.0 mmol, 47%):
mp: 151–153◦C; 31P NMR (101 MHz, DMSO-d6) δ 14.4
ppm; 13C NMR (63 MHz, DMSO-d6) δ 154.5 (s, 1C),
141.5 (d, J = 9.8 Hz, 1C), 136.9 (d, J = 125.5 Hz,
1C P),133.0 (d, J = 2.9 Hz, 1C), 132.0–131.4 (m,
3C), 130.4 (s, 1C), 129.1 (s, 1C), 126.7 (d, J = 10.9
Hz, 1C), 120.3 (s, 2C), 57.0 (s, 2C O), 55.3 (s, 2C N),
52.3 ppm (d, J = 89.0 Hz, 1C P); 1H NMR (250 MHz,
DMSO-d6) δ10.67 (broad, 1H, O H), 8.01 (m, 1H),
EXPERIMENTAL
Materials and Instruments
Unless stated otherwise, solvents and chemicals
were obtained from commercial sources and used
without any further purification. NMR spectra were
recorded with a Bruker-Analytical BZH 250/52 (250
MHz) and a Varian INOVA-400 (400 MHz). Chem-
ical shifts are reported as δ values relative to the
solvent peak. Trimethylsilane was used as a stan-
dard. All 31P NMR spectra were measured in a
proton-decoupled manner. All 13C NMR spectra were
measured in a proton-decoupled and phosphorus-
1
coupled manner. H proton spectra were measured
by a phosphorus-coupled process. Melting points
were uncorrected and measured with a Bu¨chi B-545.
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of New Dibenzo[c.e][1,2]oxaphosphorine 2-oxide Containing Diols Based on Diethanolamine 151
7.47 (m, 2H), 7.26 (m, 1H), 7.10 (m, 2H), 6.93 (m,
+ H+ 394.1778, found 394.1820; Anal. calcd. for
C20H28NO5P: C, 61.06; H, 7.17; N, 3.56; P, 7.87.
Found: C, 61.34; H, 6.97; N, 3.49; P, 7.94%.
2H), 5.37 (broad, 3H, 2CH2O H and N H), 3.52
(m, 4H, 2O CH2), 3.12 (m, 4H, 2N CH2), 2.89–
2.68 ppm (m, 2H, P CH2); IR (KBr) ν 3622 (m,
O H), 3209 (vs, O H), 3077 (m, Caryl H), 294 and
2923 (m, C H), 2869 and 2828 (m, C N), 1606 (m,
C C), 1449 (s, P Caryl), 1180 (vs, P O), 1093 (s,
C O), 1053 (s, C N), 1035 (vs, P O), 765 (s, C H
bend); HRMS (ESI) calcd. for [12C17H22NO5P] + H+
352.1308, found 352.1354.
Structural details for 3: Reflections col-
lected/unique/observed (I > 2σ): 23,502/4529/800
[R(int) = 0.8426]; parameters refined: 221; for-
mula C17H22NO5P, MM 351.33 g/mol; T = 200(2) K;
monoclinic, C2/c (no. 15, Z = 8); a = 2951.0(5))
pm; b = 1012.2(15) pm; c = 1226.2(18) pm;
α = 90◦; β = 111.33(4)◦; γ = 90◦; V 3411(9)
× 106 pm3; ρ (calcd.) = 1.368 g/cm3; absorption
coefficient = 0.188 mm−1; F(000) = 1488; Goof
(F2) = 0.788; crystal size 0.2 × 0.3 × 0.04 mm3;
index ranges −39 ≤ h ≤ 39, −13 ≤ k ≤ 13, −16 ≤ l
≤ 16; completeness to θ = 29.70: 93.6%; R1 (I >
2σ) = 0.1342, wR2 = 0.3842 (all data); largest differ-
ence peak and hole: 0.429 and −0.640 × 10−6 e/pm−3.
CCDC 811746.
Structural details for 4: Reflections col-
lected/unique/observed (I > 2σ): 27,526/5137/3116
[R(int) = 0.0606]; parameters refined: 263; for-
mula C20H28NO5P, MM 393.40 g/mol; T = 200(2) K;
monoclinic, P2(1)/c (no. 14, Z = 4); a = 1248.0
(3) pm; b = 828.1 (2) pm; c = 2082.0 (5) pm;
α = 90◦; β = 104.064 (4)◦; γ = 90◦; V 2087.2
(9) × 106 pm3; ρ (calcd.) = 1.252 g/cm3; absorp-
tion coefficient = 0.161 mm−1; F(000) = 840; Goof
(F2) = 0.960; crystal size 0.3 × 0.3 × 0.35 mm3; in-
dex ranges −16 ≤ h ≤ 16, −10 ≤ k ≤ 11, −27 ≤ l ≤
27; completeness to θ = 28.38: 92.2%; R1 (I >
2σ) = 0.0527, wR2 = 0.1388 (all data); the largest
difference peak and hole: 0.400 and −0.284 × 10−6
e/pm−3. CCDC 811747.
6-((Bis(2-hydroxyethyl)amino)methyl)-6H-dibe-
nzo[c,e][1,2]oxaphosphinine 6-oxide (2)
Heating of compound 3 (1.0 g, 2.8 mmol) using an
oil bath at 120◦C for 2 h while stirring in vacuum
(3 mbar) gave the product 2 as a transparent gum-
like substance (806 mg, 2.4 mmol, 86%): mp: 45–
47◦C; 31P NMR (101 MHz, DMSO-d6) δ 33.4 ppm; 13
C
Diethylammonium(2ꢁ-hydroxy-[1,1ꢁ-biphenyl]-2-
yl)(3-oxobutyl)phosphinate (4)
NMR (63 MHz, DMSO-d6) δ 148.9 (d, J = 8.3 Hz, 1C),
134.9 (d, J = 5.7 Hz, 1C), 133.3 (d, J = 2.0 Hz, 1C),
130.7 (d, J = 10.5 Hz, 1C), 130.6 (s, 1C), 128.4 (d,
J = 12.6 Hz, 1C), 125.5 (s, 1C), 124.5 (s, 1C), 124.1
(d, J = 113.3 Hz, 1C P), 123.8 (d, J = 9.0 Hz, 1C),
121.5 (d, J = 10.0 Hz, 1C), 119.8 (d, J = 5.7 Hz, 1C),
59.0 (s, 2C O), 57.8/57.7 (s, 2C N), 53.2 ppm (d,
DOPAcMe (5) [20] (5.0 g, 16.5 mmol) and diethy-
lamine (2.4 g, 33.0 mmol) were stirred in a round-
bottom flask at room temperature for 10 days. The
addition of 20 mL of acetonitrile and stirring of the
solution over a period of 30 min gave a white pre-
cipitate. After recrystallization from acetonitrile and
drying in air, the product 4 was obtained as white
crystals (4.10 g, 10.4 mmol, 63%): mp: 128–130◦C;
31P NMR (101 MHz, DMSO-d6) δ 23.5 ppm; 13C NMR
(63 MHz, DMSO-d6) δ 73.1 (d, J = 17.1 Hz, 1C O),
155.0 (s, 1C), 141.8 (d, J = 9.8 Hz, 1C), 138.0 (d,
J = 113.8 Hz, 1C P),134.9 (d, J = 2.6 Hz, 1C),
131.6 (d, J = 6.7 Hz, 1C), 131.4 (d, J = 9.8 Hz,
1C), 130.8 (s, 1C), 129.4 (d, J = 1.9 Hz, 1C), 128.6
(s, 1C), 126.1 (d, J = 9.9 Hz, 1C), 121.2 (s, 1C),
120.0 (s, 1C), 51.1 (s, 1C O), 41.1 (s, 2C N), 27.9 (s,
1C C O), 25.6 (d, J = 98.3 Hz, 1C P), 10.9 ppm (s,
1
J = 116.3 Hz, 1C P); H NMR (250 MHz, DMSO-
d6) 8.18 (m, 2H), 8.01 (m, 1H), 7.78 (m, 1H), 7.59
(m, 1H), 7.45 (m, 1H), 7.28 (m, 2H), 4.36 (m, 2H,
2O H), 3.38 (m, 2H, P CH2), 3.26 (m, 4H, 2O CH2),
2.64 ppm (m, 4H, 2N CH2); IR (KBr) ν 3381 (vs,
O H), 3063 (m, Caryl H), 2945 (s, C H), 2881 (s,
C N), 1594 (m, C C), 1477 (s, CH2), 1448 (s, P Caryl),
1431 (s, OH), 1202 (vs, P O), 1038 (s, C O), 917 (m,
P O), 757 (vs, C H bend); HRMS (ESI) calcd. for
[12C17H20NO4P] + H+ 334.1203, found 334.1249.
6,6ꢁ-((((6-Oxido-6H-dibenzo[c,e][1,2]oxaphosp-
hinine-6-yl)azanediyl)bis(ethane-2,1-diyl))bis-
(oxy))bis(6H-dibenzo[c,e][1,2]oxaphosphinine
6-oxide) (7)
1
2CH3); H NMR (250 MHz, DMSO-d6) δ 12.17 (2H),
8.95 (1H), 7.96 (m, 1H), 7.37 (m, 2H), 7.19 (m, 1H),
6.98 (m, 2H), 6.83 (m, 2H), 3.42 (s, 3H, O CH3),
2.89 (q, J = 7.2 Hz, 4H, 2N CH2), 2.04 (m, 2H,
CH2 C O), 1.86 (m, 2H, P CH2), 1.18 (t, J = 7.2 Hz,
6H, 2CH3); IR (KBr) ν 3447 (m, O H, N H), 1731
(vs, C O), 1456 (m, P Caryl), 1233 (s, C O), 1160
(s, P O), 1053 (m, C N), 1025 (s, P O), 762 (s,
C H bend); HRMS (ESI) calcd. for [12C20H28NO5P]
A flame-dried three-neck flask with a condenser, a
thermometer, and an addition funnel was flooded
with argon and charged with 1 (30.9 g, 143 mmol),
carbon tetrachloride (23.0 g, 150 mmol), and 200 mL
of dry chloroform. The reaction mixture was cooled
Heteroatom Chemistry DOI 10.1002/hc

152 Bykov et al.
to 5◦C with an ice bath. The addition funnel was
charged with triethylamine (15.5 g, 150 mmol) and
DEolA (5.00 g, 47.5 mmol) dissolved in 50 mL of dry
chloroform. The triethylamine mixture was added in
a dropwise manner under vigorous stirring. The re-
action temperature was not allowed to exceed 10◦C.
After 1 h, the addition was complete and the NMR
analysis indicated complete conversion of the start-
ing material. The reaction mixture was washed three
times with 50 mL water to remove triethylamine hy-
drochloride. The organic phase was isolated, dried
over MgSO4, and filtered over a small pad of alu-
minum oxide (basic). The solvent was removed in
vacuum. The spectroscopically pure product 7 was
obtained as a brown solid (24.5 g, 32.8 mmol, 69%)
mp 81–83◦C; 31P NMR (101 MHz, CDCl3) δ17.17
(P–N), 11.01/10.97 (P O) ppm; 13C NMR (63 MHz,
DMSO-d6) δ 149.7 (d, J = 7.9 Hz, 3C O), 137.1 (d,
J = 7.0 Hz, 1C), 136.8 (d, J = 7.0 Hz, 2C), 134.7
(s, 2C), 133.6 (s, 1C), 131.5 (s, 2C), 131.1 (s, 1C),
130.4/129.6 (d, J = 9.4 Hz, 3C), 126.5 (d, J = 4.3 Hz,
3C), 125.9 (s, 1C), 125.7 (s, 2C), 125.4 (d, J = 11.4 Hz,
3C), 124.8 (s, 1C), 123.9/123.8 (d, J = 177.9 Hz,
3C P), 122.6 (d, J = 11.6 Hz, 2C), 121.7/121.2 (d,
J = 11.4 Hz, 3C), 120.5–120.4 (m, 3C), 64.4–64.2
(m, 3C), 45.4–45.3 ppm (m, 3C); 1H NMR (250 MHz,
DMSO-d6) δ 8.20−8.09 (m, 6H,), 7.86–7.77 (m, 4H),
7.67 (t, J = 7.7 Hz, 1H), 7.60–7.53 (m, 2H), 7.43–
7.14 (m, 10H), 7.00–6.88 (m, 1H), 4.00–3.99 (m, 4H),
3.06–2.97 ppm (m, 4H); IR (KBr) ν 3063 (m, Caryl H),
2955 (m, C H), 1596 (m, C C), 1477 (vs, P Caryl),
1448 and 1431 (s, CH2), 1272, 1240, and 1204 (vs,
P O), 1005 (vs, P N), 919 (vs, P O), 754 (vs, C H
bend) cm−1; HRMS (ESI) calcd. for [12C40H32NO8P3]
+ H+ 748.1414, found 748.1697.
CDCl3) δ 166.7 (s, 1C O), 128.1 (s, 1CH C), 127.3 (s,
1CH2 C), 60.6/60.4 (s, 2C O), 51.3/49.6 (s, 2C N),
−0.7/ − 0.8 ppm (s, 6C Si); 1H NMR (250 MHz,
CDCl3) δ 6.66 (dd, J = 10.4 Hz, J = 16.8 Hz, 1H),
6.31 (dd, J = 16.8 Hz, J = 2.0 Hz, 1H), 5.64 (dd,
J = 10.4 Hz, J = 2.0 Hz, 1H), 3.85–3.66 (m, 4H,
2O CH2), 3.66–3.42 (m, 4H, 2N CH2), 0.08 ppm
(s, 18H, 6Si CH3); IR (KBr) ν 2958 (vs, C C H),
2901, (m, C H), 2869 (m, C N), 1654 (vs, C O),
1615 (s, C C), 1471, 1445 and 1428 (s, CH2 and
CH3), 1252 (vs, C O), 1102 (vs, Si–O), 931 and 877
(s-vs, C C H), 841 (vs, Si C), 748 (s, C H bend);
HRMS (EI) calcd. for [12C13H29NO3Si2]+ 303.1686,
found 303.1763.
3-(6-Oxido-6H-dibenzo[c,e][1,2]oxaphosphini-
ne-6-yl)-N,N-bis(2-((trimethylsilyl)oxy)ethyl)-
propanamide (12)
DOPO (1) (57.0 g, 264 mmol) and triethylamine
(3.03 g, 3.00 mmol) were dissolved in 100 mL of
dry toluene at 85◦C in a three-neck flask equipped
with a condenser, an addition funnel, and an argon
gas inlet. A solution of AcDEolA-2-TMS (11) (80.0 g,
264 mmol) in 50 mL of dry toluene was added to
the reaction mixture over a period of 15 min under
stirring in an argon atmosphere at the same temper-
ature. The reaction mixture was refluxed overnight
and then cooled to room temperature. The solvent
was removed in vacuum, and the residue was dried
in high vacuum at 10−3 mbar at 95◦C for 3 h. The
product 12 was obtained quantitatively as a white,
very viscous oil (135 g, 261 mmol, 99%): 31P NMR
(101 MHz, CDCl3) δ 39.1 ppm; 13C NMR (63 MHz,
CDCl3) δ 170.9 (d, J = 17.4 Hz, 1C O), 148.8 (d,
J = 8.1 Hz, 1C), 135.5 (d, J = 6.0 Hz, 1C), 133.2 (d,
J = 3.8 Hz, 1C), 130.5 (s, 1C), 129.8 (d, J = 11.0 Hz,
1C), 128.3 (d, J = 13.3 Hz, 1C), 125.1 (s, 1C), 124.6
(s, 1C), 124.3 (d, J = 120.4 Hz, 1C P), 123.8 (d,
J = 9.5 Hz, 1C), 122.2 (d, J = 11.0 Hz, 1C), 120.3
(d, J = 5.9 Hz, 1C), 60.3/59.8 (s, 2C O), 50.9/48.8
(s, 2C N), 25.2 (d, J = 1.8 Hz, 1C C O), 24.0 (d,
J = 99.1 Hz, 1C P), −0.7/ − 0.8 ppm (s, 6C Si); 1H
NMR (250 MHz, CDCl3) δ 7.92 (m, 3H), 7.68 (m, 1H),
7.50 (m, 1H), 7.36 (m, 1H), 7.22 (m, 2H), 3.64 (m,
4H, 2O CH2), 3.45 (m, 4H, 2N CH2), 2.77 (m, 2H,
P CH2), 2.40 (m, 2H, O C CH2), 0.06 ppm (m, 18H,
6Si CH3); HRMS (ESI) calcd. for [12C25H38NO5PSi2]
+ H+ 520.2871, found 520.2099.
N,N-Bis(2-((trimethylsilyl)oxy)ethyl)acrylamide
(11)
DEolA-2-TMS (10) [28] (75.0 g, 301 mmol) and
triethylamine (33.5 g, 331 mmol) were dissolved
in 400 mL of dry n-pentane in a three-neck flask
equipped with a reflux condenser, a mechanical stir-
rer, an addition funnel, and an argon gas inlet. The
reaction mixture was cooled with an ice bath un-
der an argon atmosphere, and a solution of acry-
loyl chloride (27.3 g, 301 mmol) in 100 mL of dry
n-pentane was added in a dropwise manner over a
period of 30 min under vigorous stirring. The reac-
tion mixture was stirred for 30 min at room temper-
ature. The formed triethylamine hydrochloride was
filtered off and washed thoroughly with n-pentane.
The organic phase was concentrated in vacuum to
yield the spectroscopically pure product 11 as a yel-
low oil (84.0 g, 277 mmol, 92%): 13C NMR (63 MHz,
N,N-Bis(2-hydroxyethyl)-3-(6-oxido-6H-dibenzo
[c,e][1,2]oxaphosphinine-6-yl)propanamide (8)
DOPAcDEolA-2-TMS (12) (144 g, 277 mmol), acetic
acid (8.30 g, 139 mmol), and 100 mL of methanol
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of New Dibenzo[c.e][1,2]oxaphosphorine 2-oxide Containing Diols Based on Diethanolamine 153
[7] Levchik, S. V.; Bright, D. A.; Dashevsky, S.; Moy P. In
Specialty Polymer Additives. Principles and Applica-
tions; Al-Malaika, S.; Golovoy, A.; Wilkie, C. A. (Eds.);
Blackwell Science: London, UK, 2001; pp. 259–269.
[8] Asrar, J.; Berger, P. A.; Hurlbut J. J Polym Sci, Polym
Chem Ed 1999, 37, 3119.
[9] Endo, S.; Kashihara, T.; Osako, A.; Shizuki, T.;
Ikegami T. US Patent 4 127 590, 1978.
[10] Seibold, S.; Scha¨fer, A.; Lohstroh, W.; Walter, O.;
Do¨ring, M. J Appl Polym Sci 2008, 108, 264.
[11] Do¨ring, M.; Bykov, Y.; Held, I. E. (Eds.). Innovative
and Sustainable Flame Retardants in Transportation;
Pinfa: Brussels, Belgium, 2010.
[12] Levchik, S. V.; Weil, E. D. In Advances in Fire Re-
tardant Materials; Horrocks, A. R., Price, D. (Eds.);
Woodhead Publishing: Cambridge, UK, 2008; pp. 49–
66.
[13] Ueda, A.; Matsumoto, T.; Imamura, T.; Tsujimoto, K.
US Patent 5 003 029, 1991.
were charged in a round-bottom flask equipped
with a condenser. The reaction mixture was re-
fluxed overnight. The solvent was removed in vac-
uum, and the residue was dried in high vacuum at
10−3 mbar at 100◦C for 8 h. The hot, viscous mass
was poured into an aluminum mould and cooled to
room temperature. The transparent glass-like solid
was crushed and then ground in a blender to give
the product 8 as a white powder in a quantita-
tive yield (103 g, 274 mmol, 99%): mp 47–50◦C;
31P NMR (101 MHz, CDCl3) δ 39.9 ppm; 13C NMR
(63 MHz, CDCl3) δ 172.2/172.0 (s, 1C O), 148.4 (d,
J = 8.0 Hz, 1C), 135.2 (d, J = 6.1 Hz, 1C), 133.4 (s,
1C), 130.5 (s, 1C), 129.8 (d, J = 11.2 Hz, 1C), 128.4
(d, J = 13.5 Hz, 1C), 125.0 (s, 1C), 124.6 (s, 1C), 123.7
(d, J = 9.6 Hz, 1C), 123.6 (d, J = 121.9 Hz, 1C P),
121.9 (d, J = 11.0 Hz, 1C), 120.1 (d, J = 5.9 Hz,
1C), 60.1/59.8 (s, 2C O), 51.7/50.2 (s, 2C N), 25.3
(d, J = 2.2 Hz, 1C C O), 23.7 ppm (d, J = 98.5 Hz,
[14] Green, J. US Patent 4 711 931, 1987.
[15] Pospiech, D.; Jehnichen, D.; Komber, H.; Korwitz, A.;
Janke, A.; Hoffmann, T.; Kretzschmar, B.; Ha¨ussler,
L.; Reuter, U.; Do¨ring, M.; Seibold, S.; Perez-Graterol,
R.; Sandler, J. K. W.; Altsta¨dt, V.; Bellucci, F.;
Camino, G. J Nanostruct Polym Nanocompos 2008,
4, 62.
[16] Herrmann, M.; Seifert, P.; Bohne, F. J. DE Patent
19962911, 2001.
[17] Gaan, S.; Sun, G.; Hutches K.; Engelhard M. H. Poly-
mer Degrad Stab 2008, 93, 99.
[18] Kim, Y. C. US Patent 4 742 088, 1988.
[19] Keglevich, G.; Szekrenyi, A.; Sipos, M.; Ludanyi, K.;
Greiner, I. Heteroat Chem 2008, 19, 207.
[20] Scha¨fer, A. Ph.D. Dissertation, University of Heidel-
berg, Heidelberg, Germany, 2008.
[21] Atherton, F. R.; Openshaw, H. T.; Todd, A. R. J Chem
Soc 1945, 660.
[22] Atherton, F. R. Q Rev Chem Soc 1949, 3, 146.
[23] Gaan, S.; Rupper, P.; Salimova, V.; Heuberger, M.;
Rabe, S.; Vogel, F. Poly Degrad Stab 2009, 94, 1125.
[24] Wang, G.; Shen, R.; Xu, Q.; Goto, M.; Zhao, Y.; Han,
L.-B. J Org Chem 2010, 75, 3890.
1
1C P); H NMR (250 MHz, CDCl3) 7.85 (m, 3H),
7.63 (m, 1H), 7.46 (m, 1H), 7.30 (m, 1H), 7.17 (m,
2H), 5.67 (broad, 2H, 2CH2O H), 3.67–3.56 (m, 4H,
2O CH2), 3.50–3.26 (m, 4H, 2N CH2), 2.86–2.56 (m,
2H, P CH2), 2.49–2.16 ppm (m, 2H, O C CH2);
IR (KBr) ν 3389 (s, O H), 3064 (w, Caryl H), 2923
(m, C H), 2865 (m, C N), 1638 (vs, C O), 1477 (s,
P Caryl), 1447 (m, CH2), 1430 (s, OH), 1229 and 1203
(vs, P O), 1044 (m, C O), 912 (m, P O), 758 (vs,
C H bend); HRMS (ESI) calcd. for [12C19H22NO5P]
+ H+ 376.1308, found 376.1381; Anal. calcd. for
C19H22NO5P: C, 60.80; H, 5.91; N, 3.73; P, 8.25.
Found: C, 60.28; H, 5.88; N, 3.62; P, 8.12%.
ACKNOWLEDGMENTS
The authors would like to thank Michael Ciesiel-
ski for inspiring discussions and support, Thomas
Zevaco for help in the interpretation of NMR spectra,
and Olaf Fuhr and Gilbert Zwick for measuring the
HR-MS.
[25] Stockland, R. A., Jr.; Taylor, R. I.; Thompson, L. E.;
Patel, P. B. Org Lett 2005, 7, 851.
[26] Keglevich, G.; Sipos, M.; Takacs, D.; Ludanyi, K. Het-
eroat Chem 2008, 19, 288.
[27] Miyabe, H.; Ueda, M.; Fujii, K.; Nishimura, A.; Naito,
T. J Org Chem 2003, 68, 5618.
[28] Wu, Y.; Zhang, M. CN Patent 101580589, 2009.
[29] SADABS, Siemens area detector absorption correc-
tion programme, Siemens, 1997.
[30] SHELX-97, G. Sheldrick, University of Go¨ttingen,
Germany, 1997. http://shelx.uni-ac.gwdg.de/SHELX/
(accessed September 21, 2011).
[31] Xpma, L. Zsolnai, G. Huttner, University of Heidel-
berg, Germany, 1997. http://www.aci.uni-heidelberg
.de/aci sub/(accessed September 21, 2011).
[32] Burnett, M. N.; Johnson, C. K. ORTEP-III: Oak Ridge
Thermal Ellipsoid Plot Program for Crystal Structure
Illustrations, Oak Ridge National Laboratory Report
ORNL-6895, 1996.
REFERENCES
[1] Keglevich, G.; Kerenyi, A. Trends Org Chem 2008, 12,
73–77.
[2] Lu, S.-Y.; Hamerton, I. Prog Polym Sci 2002, 27,
1661.
[3] Rakotomalala, M.; Wagner, S.; Do¨ring, M. Materials
2010, 3, 4300.
[4] Levchik, S. V.; Weil, E. D. Polym Int 2005, 54, 11.
[5] Sandler, S. R. US Patent 4 180 495, 1979.
[6] Weferling, N.; Schmitz, H. P. US Patent 6 242 642,
2001.
Heteroatom Chemistry DOI 10.1002/hc