Crystal Structure Models for the Aldaramide Units of Poly(pentaramides)

Abstract

The X-ray crystal structures of seven structurally related diamides, N,N′-dihexyl- and N,N′-dimethylglutaramide, N,N′-dimethylxylaramide, N,N′-dimethyl-l-arabinaramide, N,N′-dimethylribaramide monohydrate, 2,3,4-tri-O-acetyl-N,N′-dimethylxylaramide, and 2,3,4-tri-O-acetyl-N,N′-dimethyl-l-arabinaramide, were determined. These diamides were chosen as solid-state conformational models for the diamido repeating units of the corresponding polyamides. Solid-state conformations of the two N,N-dialkyglutaramides, with no pendant groups, were compared to those of their stereochemically different trihydroxy derivatives N,N′-dimethylxylaramide, l-arabinaramide and ribaramide, and the two aforementioned tri-O-acetylpentaramides.

Keywords:

• Crystal structure
• Xylaramide
• Ribaramide
• Arabinaramide
• Glutaramide
• Polyhydroxypolyamides

ACKNOWLEDGMENTS

This work was funded in part from USDA Cooperative State Research, Education and Extension Service award nos. 2005–34463–15561 and 2006–34463–16886. We thank Dr T. Groutso, University of Auckland, and Dr J. Wikaira, University of Canterbury, for collection of X-ray intensity data.