Crystal Structure of 20-Methyl-Nonatriacontane ((C₁₉H₃₉)₂CHCH₃) and Its Compatibility with Nonatriacontane (C₃₉H₈₀)

We synthesized a branched n -alkane sample M39 with a carbon number of the main chain n = 39 with the methyl group at the middle of the chain, and studied its crystalline structure and also compatibility with the corresponding linear homologue of C39. Results of SEM, DSC, X-ray diffraction, IR absorption, and Raman scattering measurements on solution-grown crystallized sample (SG-M39) and bulk-crystallized sample (BK-M39) reveal along with computer simulation that a triclinic type of crystal belonging to the space group P 1̄ is predominantly realized in BK-M39, whereas an orthorhombic type of P 2 1 2 1 2 1 is found to be coexistent for SG-M39 crystal. The phase diagram is constructed for the BK-M39/C39 binary system, which shows that the system does not form a solid solution and the respective molecules with a small amount of contaminant of another component develop their own crystal structures separately over the entire range of molar fraction of M39 from 0.05 to 0.95 studied.