Crystal structure of a zwitterionic detergent: n-octyl-2-hydroxyethylsulfoxide

The crystal structure of n-octyl-2-hydroxyethylsulfoxide (1) (space group P2(1)/c, a = 16.516(7), b = 9.053(4), c = 8.222(4) A, beta = 97.58 degrees) was determined by X-ray diffraction methods to 0.94 A resolution and refined to R = 0.050 (Rw = 0.052). In the crystal lattice the molecules are not arranged tail-to-tail, as usually observed with amphiphilic compounds, but head-to-tail and aligned in the a-axis direction. They form layers in the b, c plane which are interdigitated such that adjacent molecules in one layer are in antiparallel orientation. The packing is stabilized by intermolecular hydrogen bonds O-H--O-S. No solvent molecules were detectable.