THERMODYNAMICS OF THE THALLIUM ALKANOATES .8. HEAT-CAPACITY AND DERIVED THERMOPHYSICAL PROPERTIES OF THALLIUM(I) PROPANOATE AND PENTANOATE AT TEMPERATURES FROM 6-K TO 490-K

Heat-capacity measurements by adiabatic calorimetry at temperature T = 5 K to 350 K were supplemented by differential-scanning calorimetry ( d.s.c.) into the liquid region on thallium(I) propanoate and pentanoat e. Apparent phase transitions were noted for the propanoate for the cr ystal III-to-crystal II transition with DELTA(trans)S(m)-degrees = (1. 473 +/- 0.001) R at T = (277.7 +/- 0.1) K adiabatic calorimetry and fo r the crystal II-to-crystal I transition at (0.10 +/- 0.01) R at T = ( 268.4 +/- 0.4) K by d.s.c. and for the crystal I-to-liquid transition with DELTA(trans)S(m)-degrees = (2.70 +/- 0.09) R at T = (468.0 +/- 0. 4) K. For the VI-to-V and V-to-IV transitions of the pentanoate by adi abatic calorimetry the corresponding values are (0.359 +/- 0.002) R an d (235.1 +/- 0.1) K, (1.511 +/- 0.003) and (219.(3) +/- 1) K. For the IV-to-III, III-to-II, II-to-I, plus crystal 1-to-mesophase and mesopha se-to-isotropic liquid for the same compound the pairs of values by d. s.c. (only) are: (0.26 +/- 0.02) R and (234.6 +/- 0.4) K; (1.00 +/- 0. 04) R and (284.5 +/- 0.4) K; (0.72 +/- 0.03) R and (353.0 +/- 0.4) K; (1.50 +/- 0.05) R and (455.0 +/- 0.5) K; and (0.75 +/- 0.04) R and (48 8.0 +/- 0.8) K. Like thallium(I) butanoate, the propanoate does not sh ow a meso-tropic liquid phase.