Abstract:

The crystal structure of octadecyl hydrogen maleate was determined by Xray diffeaction method. C_(22)H_(40)O_4, Mr=368.56, triclinic, space group Pī, a=0.6833 (2), b=3.1662 (5), c=0.5392 (1) nm, α=90.63 (2), β=102.61 (2), γ=89.03 (2)°, V=1.1383 (5) nm. Z=2, Dc.=1.08 g·cm~(-3), F(000)=408, λ(Mo K_α) =0.071069 nm, μ(Mo K_α)=0.67 cm~(-1), final R=0.0465 for 1332 observations with I ≥3σ(I) and 240 variables. In the crystal OHM molecules form dimers via intermolecular hydrogen bonding between carboxyl groups. The long hydrocarbon chain of octadecyl is zigzag-like and the carbon atoms of this chain are basically coplanar. These dimers arrange along (101) plane to form a layer, then these layers stack along [010] to give the crystal structure. The van der Waals interaction intralayer is evidently larger than interlayer. On the base of the crystal structure some phenomena in the crystal growth of OHM were illustrated.

Key words: Octadecyl hydrogen maleate, Crystal structure, Soft X-ray analyzer crystal