Excess molar enthalpies of formamide plus some alkan-1-ols(C1-C6) and their correlations at 298.15 K

Excess molar enthalpies, HE for the binary systems formamide + methanol, + ethanol, + propan-1-ol, + butan-1-ol, + pentan-1-ol, and + hexan-1-ol have been measured at 298.15 K and atmospheric pressure with a Paar 1455 solution calorimeter. All the system present endothermic events and showed maximum positive HE values around 0.40-0.50 mole fraction of formamide. The HE values increases in the order: methanol < ethanol < propan-1-ol < butan-1-ol < pentan-1-ol < hexan-1-ol. Experimental showed insolubility of hexan-1-ol in formamide around x congruent to 0.5 mole fraction of formamide. The excess enthalpies of the above mentioned binary systems, were used to discuss interaction between the alkan-1-ols and formamide molecules. The results are interpreted to gain insight into the changes in molecular association equilibria and structural effects in these systems through (OHO)-H-... hydrogen bonding. The experimental data have been correlated using Redlich-Kister polynomials. In this research work, the thermodynamics models were also tested: NRTL, Wilson models and their parameters were calculated. The correlation of excess enthalpy data in the systems using NRTL model provides good results. (C) 2003 Elsevier Science B.V. All rights reserved.