X-ray study of the rotator phase of paraffins (III): Even-numbered paraffins C18H38, C2H42, C22H46, C24H5, and C26H54

Abstract

We present here a study of the ‘‘rotator’’ phase displayed by the even-numbered paraffins CnH2n+2 with n ranging from 22 to 26. We also include a few data and discussions about the crystalline phases of the even-numbered compounds with n ranging from 18 to 26. The rotator phase of these compounds is characterized by a bilayer packing with the molecular axes perpendicular to the layer planes and within each layer the packing is hexagonal. The three-dimensional space group seems to be P (63/m) mc. Finally we propose an explanation accounting for the differences between the structures of the rotator phases exhibited by the even-numbered compounds and the odd-numbered compounds.