N-Heptanoyl chloride

An AB2-type monomer (1-13, Scheme 8), was synthesized by Yamanaka et al. [133] starting from 3,5-dimethoxyphenol via a polyamic acid methyl ester precursor. The aromatic hb-PIs were prepared by chemical imidization in the presence of acetic anhydride and pyridine. The synthesized polyimides were soluble in polar aprotic solvents and showed thermal stability, with a Tajo% of 470°C in nitrogen and a Tg of 193°C. In another work by Yamanaka et al. [134], the same AB2 monomer containing free amine end groups of the precursor was end-capped with acetyl, n-heptanoyl chloride, and 4-methylphthalic anhydride. By chemical imidization of these precursors in the presence of acetic anhydride and pyridine, hb-PIs were prepared. The DB of the hb-PIs was 50% as expected. The hb-PIs showed a above 395°C, and Tg values of 189, 138, and 186°C for the end groups of acetoamide, -heptanoamide, and 4-methylphthalimide, respectively. 

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