Amino-11-undecanoic acid cyclic dimer hydrochloride

The structure of the hydrochloride salt of amino-11-undecanoic acid cyclic dimer (C22H42N2O2. HCl) corresponds to two monomeric units of nylon 11. The intensity data were collected at 203 K, Two molecules are linked by two short hydrogen bonds with O ... O distances of 2.404(6) and 2.464(6) Angstrom between half-protonated amide-O atoms, The methylene groups are all-trans except for two terminal groups, which display a (-)synclinal form (gauche). The ring is closed through bent amide groups, which are reminiscent of beta-turns in proteins. The all-trans methylene chains along both sides of the ring are not parallel, but are organized at an angle of about 10.9(6)degrees.