Benzothiophene: heat capacity, heat of transition, heat of fusion and entropy. An order--disorder transition

Journal Article · Fri Feb 05 04:00:00 EST 1954 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja01632a065· OSTI ID:7219943

Finke, H L; Gross, M E; Messerly, J F; Waddington, G

The heat capacity of benzothiophene was studied between 12 and 335/sup 0/K. The solid exhibited a large lambda/sup -/type transition between 250 and 261.6/sup 0/K. The high temperature crystals II were readily supercooled, and heat capacity measurements were made below the transition temperature both on the stable low temperature crystals I and on the supercooled crystals II. The triple point (304.50/sup 0/K) and the heat of fusion (2826.8 cal mole/sup -1/) were determined. The entropy of the solid at 298.16/sup 0/K and that of the liquid at the triple point were found to be 42.33 and 53.31 cal deg/sup -1/ mole/sup -1/, respectively. Supercooled crystals II were found to have a residual entropy of approximately R ln 2 cal deg/sup -1/ mole/sup -1/, and the transition, I ..-->.. II, was found to involve an entropy change of approximately R ln 4 cal deg/sup -1/ mole/sup -1/. It is suggested that some type of order--disorder phenomenon may cause these entropy differences between crystals I and II.

• Research Organization: Bureau of Mines, Bartlesville, OK
• OSTI ID: 7219943
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 76:3; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ENTHALPY
ENTROPY
FUSION HEAT
HETEROCYCLIC COMPOUNDS
LOW TEMPERATURE
MEDIUM TEMPERATURE
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHYSICAL PROPERTIES
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES
THIONAPHTHENES
TRANSITION HEAT
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE