Experimental solid–liquid equilibria for systems containing alkan-1-ol + 1,3-diaminopropane : Heat capacities of alkan-1-ols and amines—Thermodynamic functions of dissociation and enthalpies of melting of the congruently melting compounds for the systems (alkan-1-ol + amine)

Abstract

Solid–liquid phase diagrams (SLE) have been determined for (octan-1-ol, or nonal-1-ol, or decan-1-ol, or undecan-1-ol + 1,3-diaminopropane) mixtures. Solid addition compounds form with the empirical formulae: {(C 8H 17OH) 2·C 3H 10N 2}, {(C 9H 19OH) 2·C 3H 10N 2}, {(C 10H 21OH) 2·C 3H 10N 2}, {(C 11H 23OH) 2·C 3H 10N 2}. All these compounds are congruently melting compounds. Compound formation is attributed to a strong A–B interaction. An alkan-1-ol and amine are associated by formation O H ⋯ O and N H ⋯ N hydrogen bonds. Strong cross association between the hydroxyl and the amine group ( OH ⋯ N H 2 ) is the dominant effect and a 2:1 congruently melting solid compound is formed at low temperatures. Standard thermodynamic functions of the dissociation of the compound have been calculated. The paper includes basic thermodynamic properties of pure substances—the enthalpy of fusion, the difference in the solute heat capacity between the liquid and solid phase at the melting temperature, determined by the differential scanning calorimetry (DSC) for alkan-1-ols (nonan-1-ol, decan-1-ol and undecan-1-ol) and amines (hexylamine, octylamine, decylamine, 1,3-diaminopropane). The values of the enthalpies of fusion of congruently melting compounds in the binary systems (an alkan-1-ol + amine) are also presented.