Thermal Expansion in Alkane Diacids-Another Property Showing Alternation in an Odd-Even Series

The thermal expansion for a series of aliphatic diacids, HOOC(CH2)(n-2)COOH (n = 2-10), has been studied. Even (n = even) acids exhibit higher melting points and corresponding lower volumetric thermal expansions compared to the odd (n = odd) acids. This behavior seems to be in accordance to the Lindemann's correlation of melting point with volumetric thermal expansion. The trend of alternation is also reflected in the linear thermal expansion behavior of the series. A trend of higher thermal expansion anisotropy is observed for the odd members in the series compared to the even members.