Low-temperature thermodynamic properties of n-propyl- and n-butylbenzene

Journal Article · Wed Dec 01 04:00:00 EST 1965 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100782a038· OSTI ID:7219960

Messerly, J F; Todd, S S; Finke, H L

The heat capacities from 12 to 370/sup 0/K., heats of fusion, triple points, and purities of n-propyl-benzene and n-butylbenzene were measured in an adiabatic calorimeter. Both compounds exhibited monotropism with the metastable crystals melting 2.02/sup 0/ below the stable crystals in the case of n-propylbenzene and 0.16/sup 0/ below the stable crystals in the case of n-butyl-benzene. From the calorimetrically measured data the thermodynamic functions (G/sub s/ - H/sup 0//sub 0/)/T, (H/sub s/ - H/sup 0//sub 0/)/T, H/sub s/ - H/sup 0//sub 0/, S/sub s/, and C/sub s/ were calculated at selected temperatures for each compound for both the metastable and stable crystals and the liquid phase. For each compound, the entropies at 298.15/sup 0/K in the liquid state calculated by metastable and by stable paths agreed within experimental error, providing another check of the third law of thermodynamics. The entropy increment obtained between n-propyl- and n-butylbenzene is about 0.25 e.u greater than the constant entropy increment for the normal paraffins from C/sub 5/ to C/sub 18/ in both the liquid and ideal gas states. This slightly larger increment from n-propyl to n-butyl substitution has been noticed earlier in monoalkyl-substituted cyclopentanes and cyclohexanes. From incomplete measurements on n-decylbenzene, values of the heat of melting and triple point temperature were obtained. Estimates of the entropies of n-decylbenzene at 298.15/sup 0/K in the liquid and ideal gas states were made.

• Research Organization: Bureau of Mines, Bartlesville, OK
• OSTI ID: 7219960
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 69:12; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AROMATICS
CALORIMETRY
ENTHALPY
ENTROPY
FUSION HEAT
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES
TRANSITION HEAT