Excess properties of some methanol plus amide systems proposed as working fluids for absorption machines

Excess enthalpies and excess volumes of the binary systems methanol + N-formylmorpholine, methanol + N-methyl-2-pyrrolidine, and methanol + 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone at 298.15 K and atmospheric pressure have been measured. Excess enthalpies H-E were measured in a Calvet microcalorimeter and excess volume V-E in a vibrating-tube densimeter. All the V-E values were negative, and the H-E values were also negative except those of the mnethanol + N-formylmorpholine system. The results are discussed qualitatively in terms of molecular interactions. A version of the UNIFAC group contribution model has been used to compare the predicted and experimental H-E results.