1,17-Diphenyl-2,4,6,8,10,12,14,16-octaoxaheptadecane.

The title compound, C(21)H(28)O(8), crystallizes with two independent molecules, each with a crystallographic twofold axis passing through the central CH(2) group. The two molecules have different orientations of the terminal benzyl groups. The average C-O bond length in the polyoxymethylene helix, corrected for librational motion, is 1.419 A. The molecules are connected into layers by intermolecular C-H...O and C-H...pi(phenyl) interactions.