MACROCYCLIC ARAMIDS (2N-AZA[2N]PARACYCLOPHANE-2N-ONES) - NEW INTERMEDIATES FOR THE SYNTHESIS OF P-ARAMIDS

An easy route to a new class of n-azapara[2n] cyclophane-n-ones, N-sub stituted p-oriented cyclic aromatic amide (cycloaramid) oligomers, is described. The bulky diamine, N,N'-di-sec-butyl-p-phonylenediamine is condensed with terephthaloyl dichloride at elevated temperature in o-d ichlorobenzene to provide a high yield of N,N'-di-sec-butyl-p-phenylen eterephthalamide cyclic oligomers (from dimer to tridecamer). The cycl ization is favored by the cis conformation of the N-substituted amide bonds present in the growing chain. Ring opening polymerization of the se new cycloaramids to high molecular weight linear polymers can be ef fected in the melt phase with highly nucleophilic catalysts, such as 1 ,3-dialkylimidazole-2-thiones especially when an acid cocatalyst is em ployed. The N-substituted polymers yield crystalline films and fibers with an axial repeat length which can only be explained by an unexpect ed trans conformation of the amide bonds. The facile synthesis of othe r macrocyclic amides by the steric control of macrocyclization by N-su bstitution of the amide bond is also described.