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Molecular Association of Hydrogen Bonding Solutes, o -, m -, and p -Cresol, in Carbon Tetrachloride

1974; NRC Research Press; Volume: 52; Issue: 4 Linguagem: Inglês

10.1139/v74-100

1480-3291

Earl M. Woolley, Dennis S. Rushforth,

Thermodynamic properties of mixtures

The intermolecular hydrogen-bonding self-association of the three cresols in CCl 4 solutions at 25 °C has been investigated by calorimetric means. Calorimetrically determined heats of dilution of each of the cresols in anhydrous CCl 4 are interpreted in terms of two different models: (i) dimerization and trimerization self-association reactions, and (ii) dimerization followed by stepwise polymerization self-association reactions. Values of K, ΔH 0 , and ΔS 0 for these reactions are calculated using least-squares and other methods. Results show that o-cresol is clearly less associated in anhydrous CCl 4 solution at 25 °C than either m- or p-cresol. Values of K 2 and K 3 (both based on molar concentrations of solutes) and ΔH 2 0 and ΔH 3 0 (kcal) for the reactions [Formula: see text] respectively, are o-cresol: 0.7, 1. 3 ,−3. 4 ,−12. 5 ; m-cresol: 0.8, 5. 0 ,−5. 0 ,−13. 6 ; p-cresol: 0.3 5 , 6. 5 ,−5. 5 ,−13. 4 . Values of K 2 and K s (both based on molar concentrations of solutes) and ΔH 2 0 and ΔH s 0 (kcal) for the reactions [Formula: see text] (all n > 2 with same K s and ΔH S 0 ), respectively, are o-cresol: 0.7, 1.6, −4.2, −4. 5 ; m-cresol: 1.2, 4.0, −5. 0 , −4. 3 ; p-cresol: 1.0, 7. 0 , −3. 3 , −3. 5 .