THE THERMAL-PROPERTIES OF 3 (CL-, BR-, I-) PARA-HALOTOLUENES - FORMATION OF GLASSY CRYSTALS

The heat capacities of three para-halotoluenes, p-chlorotoluene, p-bro motoluene and p-iodotoluene, were measured with an adiabatic calorimet er. All three compounds showed the formation of glassy crystals. The g lass transition temperatures are 220, 242 and 250 K respectively. The temperature and enthalpies of fusion are: for p-chlorotoluene, 280.69 +/- 0.01 K and 13554 J mol(-1); for p-bromotoluene, 299.94 +/- 0.01 K and 15127 J mol(-1); and for p-iodotoluene, 306.70 +/- 0.05 K and 1496 3 J mol(-1). The heat capacity of p-iodotoluene was measured from 5 K; the derived thermodynamic properties are given. Those of the other co mpounds were measured from 80 K.