Die Schmelzpunktalternanz der kurzkettigenn‐Alkane: Einkristall‐Röntgenstrukturanalysen von Propan bei 30 K und vonn‐Butan bisn‐Nonan bei 90 K

Abstract

Eine weniger dichte Packung weisen die ungeradzahligen n‐Alkane gegenüber den geradzahligen auf und folglich auch jeweils niedrigere Schmelztemperaturen. Dies rührt daher, daß die geradzahligen n‐Alkane an beiden Enden optimale intermolekulare Wechselwirkungen eingehen können (im Bild links), die ungeradzahligen aber nur an einem Ende – am anderen Ende sind die Abstände jeweils größer (rechts).

Odd–even effect of melting finite polymer film on square lattice

“…There is a similar but different phenomena in an experimental measurement of the melting temperature of n-alkanes C n H 2n+2 powder. The temperature curve connecting the odd number of length of C n H 2n+2 is below that for the even number of length of C n H 2n+2 [5] [6]. Even though here we study the width dependence of dimer film which is different from the three dimensional experimental system, this theory maybe is still helpful for an exact understanding on the odd-even effect of polymer powders.…”

“…The melting point of fatty acids with odd number of chain length are below its neighboring even number of chain length [4]. When the length of the n-alkanes increases by one unit from an even number to its next neighboring odd number, the melting temperature increases by a relatively smaller value compared with the case that from an odd number to even number [5] [6]. This odd-even effect is diminished when the chain length becomes longer than 16.…”