Protonation enthalpies of ethylenediamine, 1,6-hexanediamine, 1,8-octanediamine and 1,10-decanediamine were determined at 258C in NaCl aqueous solutions, 0 < I 3 mol dm ÿ3 (0 < I 5 mol dm ÿ3, for 1,6-hexanediamine). The dependence on ionic strength of DH0 can be expressed by the equation ÿDH0 ÿDH0 I 0 a1I a2I2. Values of enthalpy changes at different ionic strengths made it possible to determine the temperature gradients of the speci®c interaction parameters of Pitzer equations. The functions DG0 and DH0 versus ionic strength are very similar and the resulting T DS0 values are quite low and fairly constant. Other empirical relationships for the dependence of both DH0 and DG0 on alkyl chain length and ionic strength are reported.

Medium effects on the protonation enthalpies of linear diamines in NaCl aqueous solutions, at 25°C

DE STEFANO, Concetta;FOTI, Claudia;GIUFFRE', Ottavia
2000

Abstract

Protonation enthalpies of ethylenediamine, 1,6-hexanediamine, 1,8-octanediamine and 1,10-decanediamine were determined at 258C in NaCl aqueous solutions, 0 < I 3 mol dm ÿ3 (0 < I 5 mol dm ÿ3, for 1,6-hexanediamine). The dependence on ionic strength of DH0 can be expressed by the equation ÿDH0 ÿDH0 I 0 a1I a2I2. Values of enthalpy changes at different ionic strengths made it possible to determine the temperature gradients of the speci®c interaction parameters of Pitzer equations. The functions DG0 and DH0 versus ionic strength are very similar and the resulting T DS0 values are quite low and fairly constant. Other empirical relationships for the dependence of both DH0 and DG0 on alkyl chain length and ionic strength are reported.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11570/1587360
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