Thermochemical comparisons of homogeneous and heterogeneous acids and bases. 1. Sulfonic acid solutions and resins as prototype Broensted acids
Heats of ionization by thermometric titration for a series of bases (or acids) can be used to compare solid acids (or bases) with liquid analogues bearing the same functionalities in homogeneous solutions. The method is demonstrated for Broensted acids by reacting a series of substituted nitrogen bases with solutions of p-toluenesulfonic acid (PTSA) in acetonitrile and with suspensions of the microporous polymeric arylsulfonic acid resin-Dowex 50W-X8 in the same solvent. Under well-controlled anhydrous conditions there is a good correlation (r = 0.992) between the heats of reaction of the bases with the homogeneous and heterogeneous acid systems, but the homogeneous system gives a more exothermic interaction by 3-4 kcal mol/sup -1/ for a series of 29 substituted pyrimidines, anilines, and some other amines. This difference may be attributed to homohydrogen bonding interactions between excess acid and sulfonate anion sites which are more restricted geometrically in the resin than in solution. Other factors which affect the enthalpy change for the acid-base interaction are the acid/base ratio, the water content of the sulfonic acid, the solvent, and the resin structure (e.g., microporous vs. macroporous). Steric hindrance in the base does not differentiate solid from homogeneous acid. In addition to the use of titration calorimetry, heats of immersion are reported for the Dowex-arylsulfonic acid resins and the Nafion-perfluorinated sulfonic acid resin in a series of basic liquids. The results are compared with each other and with those from a previous study of several varieties of coal.
- Research Organization:
- Duke Univ., Durham, NC
- DOE Contract Number:
- FG22-82PC50807
- OSTI ID:
- 5391096
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 108:16
- Country of Publication:
- United States
- Language:
- English
Similar Records
Reaction calorimetry for coal chemistry and catalysis. Annual report, August 1, 1982-July 30, 1983. [Heats of immersion]
Reaction calorimetry for coal chemistry and catalysis. Annual report, August 1, 1983-July 30, 1984. [Heats of immersion]
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BASES
REACTION HEAT
NITROGEN COMPOUNDS
SULFONIC ACIDS
TOLUENE
ACETONITRILE
CHEMICAL BONDS
EXPERIMENTAL DATA
IONIZATION
PH VALUE
THERMODYNAMICS
THERMOMETRIC TITRATION
ALKYLATED AROMATICS
AROMATICS
DATA
ENTHALPY
HYDROCARBONS
INFORMATION
NITRILES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TITRATION
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)