LAUSR

The solid–liquid equilibrium phase diagram and thermochemical studies on two binary organic systems involving N-methylurea (MU) with 4-nitrophenol (NP) and 3-nitrobenzoic acid NBA were studied. Both systems show the formation of an equimolar intermolecular compound (IMC) and two eutectics (E1 and E2) one on either side of the IMC. Thermodynamic parameters such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy and excess thermodynamic functions of intermolecular compounds and eutectics were calculated using the experimentally determined enthalpy of fusion by the DSC method. The spectroscopic studies, FTIR and NMR, of both the IMCs along with their parent compounds revealed the hydrogen bonding association between the parent moieties forming the complex. The findings were also confirmed by the appearance of new peaks in the powder XRD of the complexes in addition to their parent compounds.