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Macro‐cyclic aramids (2n‐AZA[2 n ]paracyclophane‐2n‐ones):new intermediates for the synthesis of p ‐aramids
Author(s) -
Memeger Wesley,
Lazar Joseph,
Ovenall Derick,
Arduengo Anthony J.,
Leach Roger A.
Publication year - 1994
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19940770114
Subject(s) - terephthaloyl chloride , amide , steric effects , chemistry , yield (engineering) , polymerization , polymer chemistry , dimer , diamine , cyclophane , polyamide , crystallography , polymer , stereochemistry , materials science , copolymer , organic chemistry , crystal structure , metallurgy
An easy route to a new class of n‐azapara[2 n ] cyclophane‐n‐ones, N‐substituted p ‐oriented cyclic aromatic amide (cycloaramid) oligomers, is described. The bulky diamine, N, N′‐di‐ sec ‐butyl‐ p ‐phenylenediamine is condensed with terephthaloyl dichloride at elevated temperature in o ‐dichlorobenzene to provide a high yield of N, N′‐di‐sec‐butyl‐ p ‐phenyleneterephthalamide cyclic oligomers (from dimer to tridecamer). The cyclization is favored by the cis conformation of the N‐substituted amide bonds present in the growing chain. Ring opening polymerization of these new cycloaramids to high molecular weight linear polymers can be effected in the melt phase with highly nucleophilic catalysts, such as 1,3‐dialkylimidazole‐2‐thiones especially when an acid cocatalyst is employed. The N‐substituted polymers yield crystalline films and fibers with an axial repeat length which can only be explained by an unexpected trans conformation of the amide bonds. The facile synthesis of other macrocyclic amides by the steric control of macrocyclization by N‐substitution of the amide bond is also described.