X‐ray diffraction studies of monomeric and polymeric 5,7‐dodecadiynylene bis(<i>N</i>‐ethylcarbamate) (ETCD)

Abstract

Abstract Crystals of the monomer and polymer of the bis‐ethylurethane of 5,7‐dodecadiyne‐l, 12‐diol ( 1 a , ETCD), systematic name: 5,7‐dodecadiynylene bis( N ‐ethylcarbamate) have been studied by X‐ray powder and single‐crystal photographic techniques. Lattice constants at 20°C were obtained from both single‐crystal and powder data and are in satisfactory agreement with a previous report. Lattice constants at 130–135°C were obtained from powder data and reveal that the lattice expands in volume by 4% on heating from 20°C, in contrast to a previous report which indicated a volume contraction on heating. Rotation photographs of poly(ETCD) crystals before and after extraction of unpolymerized monomer with boiling methanol reveal that solvent extraction renders many reflections more diffuse. Weissenberg h 0 l ‐photographs of the polymer reveal sufficient disorder so as to preclude a high‐precision structural determination. Rotation and Weissenberg photographs of monomeric ETCD at 20°C manifest the major reflections of the polymer.