The Synthesis and the Physical Properties of Normal Higher Primary Alcohols. V. Thermal and X-Ray Studies of the Polymorphism of Alcohols of Odd Carbon Numbers from Undecanol to Heptatriacontanol

On the phase transition of n-higher alcohols with odd carbon atoms from undecanol (C11) to heptatriacontanol (C37), thermal analyses and X-ray pattern measurements were made, with the following results: 1. Tridecanol (C13) shows an irreversible transition which appers only on cooling. A reversible transition sets in at pentadecanol (C15) and continues to the end member of the series (C37). 2. X-Ray pattern measurements indicated that, in the alcohols up to nonacosanol (C29), the transtition is β to α, while in the alcohols above C29 the transition is γ2 to α. 3. Presumably, the γ2 to α transition is gradual. 4. The properties of the α forms change gradually with an increase in the chain length. 5. The results of the present study and those of previous studies with the even series have been discussed from the configurations of the β and γ1 forms, as determined by X-ray structure analyses.