Melting Mechanisms of Ionic Salts: Tetra-n-Amyl Ammonium Thiocyanate

摘要

A study is reported of the melting of ((n-amyl)4N)(+)SCN(-) (m.p. 49.5C) using dilatometry, phase-transition calorimetry, and microscopy. The changes in the electrical conductance, and in UV absorption for the fusion process are also reported. A solid-state transition occurs at 42C. Rapid cooling results in incompletely crystallized samples, with corresponding variations in the temperatures and enthalpies for the solid state transition and for fusion. The melting mechanism is examined relatively to the fusion of paraffinic hydrocarbons and ionic crystals. It is apparent that the solid-state transition (42C) may be attributed to a kink-block type transition within the amyl groups of the quarternary ammonium ion. (Author)