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In a 500 mL round bottom flask with a magnetic stirrer were introduced o-TDA
(10 g, 0.0472 moles) in 400 mL DCM (total conc. ~ 6%). The contents were
stirred until the diamine dissolved. Phthalic anhydride (PA) (13.974 g, 0.0943
moles, 2 mole equivalent) was gradually added to the solution and the mixture
was stirred overnight at RT. The compound was analysed by
1
H NMR and the
chemical structure was confirmed.
1
H NMR (DMSO);
10.36 (s, COOH); 7.9-7.8 (d, J = 6.6 Hz, Aromatic); 7.70-
7.51 (m, Aromatic); 7.0 (d, J = 8.2 Hz, Aromatic); 2.02 (s, CH
3
).
At one point a dense white precipitate began to form indicating the formation
of the amic acid. After 24 h the solution was filtered and the white powder was
left to dry. 22.12 g of model compound
δ
A
was obtained after drying (Yield 92.3%).
2.2.2. (b) Synthesis of model compound
(Bisphthalamic acid of
1,3-bis(3-propyl) tetramethyl disiloxane)
The synthesis of model compound was sluggish due to reactivity of SiDA. The
synthesis scheme is shown in Figure 6.
23 mL of THF was added to a 50 mL single necked round bottomed flask fitted
with a calcium chloride guard tube. Then 2 g of SiDA was introduced and dis-
solved using a magnetic stirrer. 2.6 g of freshly dried phthalic anhydride (PA) was
gradually added into the above solution in instalments. It took about 5-10 minutes
for the PA to dissolve completely. The flask was fitted with the calcium chloride
guard tube. The solution was stirred overnight at room temperature (25
B
C).
The next morning, the solution was precipitated from hexane and the mixture was
kept in a refrigerator.
±
2
°
Figure 6. Model compound B synthesis scheme.
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