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ring. The contents were heated at 60°C for 4-5 h. Cyclodehydration of itaconamic
acid was carried out using acetic anhydride and fused sodium acetate.The con-
tents were heated for 4-5 h at 60°C. The imides were precipitated in ice-cold wa-
ter, filtered, washed successively with water, sodium bicarbonate solution, water,
and dried in vacuum oven at 50-75°C. The purification was done by column
chromatography using a silica column and chloroform as an eluent. Bisitaconim-
ides having sulfone and phosphine oxide groups were prepared by refluxing an-
hydride and amine in glacial acetic acid.
2.3. Characterisation
Structural characterisation was done by recording the IR spectra in a film form or
in KBr pellets using BioRad Digilab FTS-40 FT-IR spectrometer.
1
H-NMR spectra were recorded on a Bruker AC 300 MHz spectrometer using
DMSO-d
6
/ CDCl
3
as solvents and tetramethylsilane (TMS) as an internal standard.
A DuPont 2100 thermal analyser having 910 DSC and 951 TG modules was
used for thermal characterisation. DSC scans were recorded in static air atmos-
phere using 7
C. The char-
acteristic melting temperature (T
m
), onset temperature of curing (T
1
), exothermic
peak temperature (T
exo
) and temperature of completion of exotherm (T
2
) were re-
corded. TG studies were carried out in nitrogen atmosphere (flow rate
60 cm
3
/min) at a heating rate of 20
2.5 mg of sample in a temperature range of 50-350
±
°
°
C/min (sample weight 10
±
2 mg).
3. RESULTS AND DISCUSSION
3.1. Isomerisation of bisitaconimides
In order to investigate the isomerisation of bisitaconimides to biscitraconimides
[7], the synthesis was carried out in solvents of different polarities. In Table 1 the
details of the reaction conditions and sample designations are given.
Table 1.
Preparation of bisitaconamic acids and bisitaconimides: Details of reaction conditions and sample
designation
Bisitaconamic acid
Bisitaconimide
Itaconic anhydride = 2.24 g Bisitaconamic acid = 3.5 g
4,4'-diaminodiphenyl ether = 2 g Acetic anhydride = 1.5 mL
Temperature = 60°C Anhyd. sodium acetate = 1 g
Solvent = 40 mL Solvent = 20 mL
Bisitaconamic acid
S. No
Bisitaconimide
Solvent
Sample designation
Solvent
Sample designation
1
Tetrahydrofuran
IAF
Tetrahydrofuran
IEF
2
Acetone
IAA
Acetone
IEA
3
Chloroform
IAC
Chloroform
Toluene
Acetic anhydride
IEC
IET
IEN
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