525
Acta Cryst. (1999). B55, 525±529
Single-crystal structure analysis of a novel aryl phosphinate diglycidyl ether
Ching-Sheng Cho,a* Wen-Bin Liaub and Leo-Wang Chena
aDepartment of Chemical Engineering, National Taiwan University, Taiwan, and bInstitute of Materials Science and
Engineering, National Taiwan University, Taiwan. E-mail: chlo@ms.cc.ntu.edu.tw
(Received 4 March 1998; accepted 5 January 1999)
Abstract
pendent groups to improve the ¯ame resistance are
scarce.
The crystal structure of 10-[2,5-bis(2,3-epoxy-1-prop-
oxy)phenyl]-9-oxa-10-phosphaphenanthren-10-one has
been studied by single-crystal X-ray diffraction. The
unit cell of C24H21O6P, Mr = 436.4, is triclinic, P1, with
a = 8.507 (3), b = 10.613 (4), c = 12.457 (3) A, ꢀ =
Recently, a novel aryl phosphinate diglycidyl ether,
10-[2,5-bis(2,3-epoxy-1-propoxy)phenyl]-9-oxa-10-phos-
phaphenanthren-10-one (DHQEP; Fig. 1), was synthe-
sized in which a cyclic organophosphorus compound was
incorporated into the molecular structure of the epoxy
ether and grafted onto the main chain. This aryl phos-
phinate epoxy ether is expected to be highly effective in
increasing the ¯ame resistance of the corresponding
epoxy resin. During the determination of the structure
of DHQEP by 1H- and 13C-NMR, it was found that the
chemical shifts of the protons of the glycidyl ether group
at one end of DHQEP were similar to those observed in
the glycidyl ether group of the diglycidyl ether of
bisphenol A (DGEBA, Fig. 1). However, the chemical
shifts of the protons of the glycidyl ether group at the
other end of DHQEP were quite different from those
Å
Ê
3
ꢀ
Ê
80.05 (3), ꢁ = 71.38 (2), ꢂ = 76.69 (3) , V = 1031.1 (6) A ,
Z = 2, Dx = 1.406 Mg m 3 and ꢃ(Mo Kꢀ) = 0.17 mm
.
1
The ®nal R (wR) is 0.063 (0.057) {w = 1/[ꢄ2(F) +
0.0004F2]} for 3619 unique re¯ections measured at
295 K. The aryl phosphinate group bonded to the
central phenyl ring comes close to one of the two
glycidyl ether groups, the epoxide ring of which is
ordered. The epoxide ring far from the aryl phosphinate
group is disordered. The NMR chemical shifts of the
protons of the glycidyl ether group close to the aryl
phosphinate group are reduced by the `ring-current
effect'.
1. Introduction
Despite their comparatively high cost, epoxy resins have
achieved signi®cant importance as industrial materials
with applications as surface coatings, adhesives, tooling
compounds, matrices in composites and in the encap-
sulation of electronic components (Lee & Neville, 1972;
Lubin, 1982). Epoxy resins can be cured with amines or
anhydrides and the cross linking of epoxy resins may be
carried out either through the epoxy groups or the
hydroxyl groups. Although epoxy resins have many
attractive properties, such as low shrinkage on curing,
good alkali resistance, and weather resistance, the
¯ammability of epoxy resins is a disadvantage in appli-
cations requiring high ¯ame resistance. Thus, modifying
the structures of epoxy resins to improve their ¯ame
resistance has recently received increasing attention.
Introduction of certain phosphorus groups, such as
phosphate (Flury et al., 1996), phosphonate (Liu et al.,
1996), phosphinate (Welch & Paxton, 1968; Vogt et al.,
1968), cyclic phosphine oxide (Shau & Wang, 1996),
phosphine oxide and thioxophosphine oxide (Gentzkow
et al., 1991), into the backbone of epoxy resins to
enhance the ¯ame resistance has been reported.
However, reports of the modi®cation of the structures of
epoxy resins by introducing phosphorus groups as
Fig. 1. The synthesis of DHQEP and the schematic structure of
DGEBA.
# 1999 International Union of Crystallography
Printed in Great Britain ± all rights reserved
Acta Crystallographica Section B
ISSN 0108-7681 # 1999