Crystal and molecular structure of optically active poly‐D(–)‐β‐methyl‐ε‐caproamide

Abstract

AbstractThe investigation of the crystal and molecular structure of optically active poly‐D(–)‐β‐methyl‐ε‐caproamide was carried out in two stages. The molecular conformation was first studied by means of Fourier transform methods and the crystal packing was later deduced by detailed structure factor calculations. The structure thus established bears some close resemblance to that characteristic of the γ modification of unsubstituted nylon 6. A marked shortening of the chain along its axis is produced by the presence of a methyl group in the β position. This causes the rotation about the skeleton bonds adjacent to the amide bonds, whereas the rest of the chain retains its trans planar stable conformation. The hydrogen bonds of normal length (2.85 A.) crosslink the molecules in parallel sheets in planes parallel to the (100) plane which are translated with respect to each other by 5/14 of the b axis in the P monoclinic space group.