The Alkanes

Abstract

Crystalline n-alkanes were among the first materials studied by quantitative electron crystallographic techniques. Rigamonti (1936) had obtained hk0 electron diffraction intensity data from thin films of a paraffin fraction melting in the range 49–50 °C, as well as pure n-C₃₁H₆₄ obtained from the synthetic reduction of palmitone. Structure factors were computed from electron form factors derived from the Mott formula via x-ray scattering factor tables. No Lorentz correction was made to the observed intensity data. A chain model was constructed from the earlier x-ray model of Müller (1930) and the rotational parameter 90° — ϕ) of the projected chain plane (Figure 8.1), where ϕ is the setting angle, was varied from 20 to 50° with most likely values found between 35 and 40°. The C-H distance was estimated to lie in the range 1.1 to 1.4 Å.