Electron diffraction determination of chain packing of a ketonic insect wax

Abstract

Single crystal electron diffraction patterns are obtained from thin microcrystals of two polymorphic forms of a pure ketonic wax secreted by the wooly alder aphid, Prociphilus tessellatus. One crystalline form gives intensity data which agree well with the commonly observed O ⊥ methylene subcell. The unit cell constants for the projection are a = 7.52 A ̊ and b = 5.05 A ̊ . The other polymorph, which is found less often, is a rectangular supercell with pseudohexagonal symmetry in the intensity-weighted hk0 reciprocal net. The supercell parameters in projection are a = 42.06 A ̊ , and b = 9.12 A ̊ with the inner order hexad of intense spots occurring at 4.20 Å.