Étude comparative dans la série des dibenzamido-alcanes, composés modèles des poly(oligométhylènes téréphtalamides)

Abstract

The dibenzamido alcanes, nDBN, for n = 2–10, have been synthesized and characterized by X-ray diffraction and infrared and Raman spectroscopy. From X-ray diffraction it was observed than the dihedral angle ε between the aromatic ring and the amido group averaged 28.3° and did not vary significantly with n. The torsion angle τ between the amide group and the aliphatic chain was found to be near 180° for n = 4, 6, 8, and 10. However, for n = 2, 3, 5, and 7, τ averaged 98°. In this last case the plane of the aliphatic chain is nearly perpendicular to the plane of the amide group. The study of ir and Raman spectra in relation to conformation revealed that the position of the amide V band depends on the value of the τ angle and could be used to infer if the latter is close to 180° or not.