New highly phenylated bis(phthalic) and bis(naphthalic) anhydrides and polyimides therefrom - Polyimides and Other High Temperature Polymers - page 98

2. EXPERIMENTAL

The starting compounds and solvents were purified according to conventional
techniques.
The 1 H and 13 C NMR spectra were recorded in CDCl 3 with a Bruker AMX-400
spectrometer operating at 400.13 and 100.61 MHz, respectively. Tetramethylsi-
lane was used as an internal standard. The purity of the individual compounds
was checked by thin-layer chromatography. Measurements were performed in
benzene using Silufol-UV-245 plates, and they were developed under UV light.
The IR and Raman spectra were measured with a Perkin-Elmer 1720X spectro-
photometer. DSC and TGA experiments were carried out with DSC7 and TGA7
instruments, respectively. The heating rate was 20

C/min. The dielectric constants
of the polymer films were measured with an E7-8 CRL digital meter at an electric
field frequency of 1 kHz and a humidity of 0 and 50%.

°

2.1. Monomers

2.1.1. Synthesis of 4,4'-bis(2,3,6-triphenyl-4,5-dicarboxyphenyl) benzophenone
dianhydride ( )

A two-necked flask equipped with a reflux condenser and a stirrer was charged
with 4,4

II

(2.46 g,
3.1 mmol), maleic anhydride (0.61 g, 6.25 mmol), and bromobenzene (7.5 ml).
The reaction mixture was boiled for 3 h, cooled, and a solution of bromine (0.55
ml) in bromobenzene (0.9 ml) was slowly added dropwise. After the mixture was
boiled for another 3 h, it was then poured into hexane (150 ml). The precipitate
was filtered off and dried under vacuum to provide compound

′ -bis(2,4,5-triphenylcyclopentadien-1-on-3-yl)-benzophenone 1

II (2.51 g, 87%) as

a white crystalline powder; M.p.= 361-362°C.
For C 65 H 38 O 7 , Calcd. (%): C, 83.85; H, 4.11.
Found (%): C, 83.90; H, 4.15.
IR (v, cm -1 ): 1779, 1843 (C=O of anhydride), 1661 (C=O of benzophenone),
1605 (C=C of aromatic ring).
1 H NMR (CDCl 2 ,

, ppm): 6.76-6.77 (m, 4H), 6.85 (d, 4H, J = 8.1 Hz), 6.90-
7.00 (m, 6H), 7.00-7.18 (m, 12H), 7.18-7.30 (m, 12H).
13

δ

, ppm): 126.78 (2C), 126.85 (2C), 126.90 (2C), 127.11
(2C), 127.15 (2C), 127.24 (2C), 127.47 (2C), 127.55 (2C), 127.62 (2C), 127.65
(2C), 127.79 (2C), 127.89 (2C), 128.00 (2C), 128.02 (2C), 128.45 (2C), 128.59
(2C), 129.39 (2C), 129.45 (2C), 129.55 (2C), 130.19 (2C), 130.30 (2C), 133.81
(2C), 135.69 (2C), 140.84 (2C), 141.35 (2C), 149.47 (2C), 161.21 (-CO-dianhy-
dride, 4C), 195.28 (-CO-benzophenone, 1C).

C NMR (CDC1 3 ,

δ

2.1.2. Synthesis of 4,4 -bis[2,3,5,6-tetraphenyl-(4,5-dicarboxynaphth-1-yl)phenyl-

benzophenone dianhydride (

′

)
A three-necked flask equipped with a reflux condenser, a stirrer, and an inlet for
feeding argon was charged with compound

III

II (0.79 g, 1 mmol), 4-(phenyl-