Reversible Phase Transition of 4-Ethoxybenzenammonium Iodide.

A new phase transition compound 4-ethoxybenzenammonium iodide ( 1) (C8H12ON+ ·I-) was determined. Differential scanning calorimetry (DSC) results show sharp peaks appear at 157.93 K (-115.22 °C) on heating and 157.00 K (-116.15 °C) on cooling with Δ H = 120.34 J ·mol-1, Δ S = 0.762 J ·mol-1 ·K-1. The dielectric measurements appear clear slope change, which matches well as observed in the DSC results. The crystal structure analyze shows that the space group changes from P21 at 103(2) K to P21/ c at 298(2) K during the phase transition process. The essential difference between the two temperature structures is the relative orientation of the oxyethyl group to the benzene ring, slight displacements of the anionic iodine and the packing of the molecular species. [ABSTRACT FROM AUTHOR]