Solid—solid phase transitions determined by differential scanning calorimetry part IV. New transitions in tetrahedral substances

Abstract

Data are presented to show that tris(hydroxymethyl)acetic acid, monochloro-pentaerythritol, monofluoropentaerythritol, difluoropentaerythritol, monoamino-pentaerythritol, and diaminopentaerythritol exhibit solid-state transitions to a plastic crystalline state. Transitional enthalpies in many of these substances are lower than might be expected by analogy with related structures, suggesting that some configurational contributions to their entropy increments have been inhibited.