Synthesis and characterization of novel optically active and flame-retardant heterocyclic polyimides

Tetrachlorophthalic anhydride (1) was reacted with L-leucine (2) in toluene solution at refluxing temperature in the presence of triethylamine and the resulting imide-acid (4) was obtained in quantitative yield. The compound (4) was converted to the N-(tetrachlorophthaloyl)-L-leucine acid chloride ( 5) by reaction with thionyl chloride. The reaction of this acid chloride (5 ) with isoeugenol (6) was carried out in chloroform and novel optically act ive isoeugenol ester derivative (7) as a chiral monomer was obtained in hig h yield. The compound (7) was characterized by H-1-NMR, IR, Mass and elemen tal analysis, and then was used for the preparation of model compound (10) and polymerization reactions. 4-Phenyl-1,2,4-triazoline-3,5-dione, PhTD (8) was allowed to react with compound (7). The reaction is very fast, and giv es only one diastereomer of (10) via Diels-Alder and ene pathways in excell ent yield. The polymerization reactions of novel monomer (7) with bistriazo linediones [bis-(p-3,5-dioxo-1,2,4-triazolin-4-ylphenyl)methane (II) and 1, 6-bis-(3,5-dioxo-1,2,4-triazolin-4-yl)hexane] (12) were carried out in N,N- dimethylacetamide (DMAc) at room temperature. The reactions are exothermic, fast, and give novel optically active polymers (13) and (14) via repetitiv e Diels-Alder-ene polyaddition reactions. The resulting polymers are optica lly active, thermally stable, and flame resistant. All of the above compoun ds were fully characterized by IR, 1H-NMR, elemental analysis, and specific rotation. Some structural characterization and physical properties of thes e novel heterocyclic polyimides are reported. (C) 2000 John Wiley & Sons, I nc.