Intermolecular interaction studies of binary mixtures of a ketoester and carbonyl compounds. I: Excess volumes of binary mixtures of ethyl acetoacetate with aliphatic ketones at 298.15K

Density data on binary mixtures of ethyl acetoacetate and aliphatic ketones containing four to six carbon atoms have been obtained with a single capillary pyknometer at 298.15K over the entire range of solvent composition. Excess volumes of the binary mixtures, calculated from the density data, for the binary mixtures of ethyl acetoacetate with the straight chain ketones, butan-2-one and pentan-3-one are negative over the entire range of solvent composition. The negative excess volumes are attributed to volume reductions arising from the fitting of the ketone molecules having smaller molecular volumes into the ethyl acetoacetate molecules with larger molecular volumes. The excess volumes of the branched aliphatic ketones, 3-methylbutan-2-one and 4-methylpentan-2-one are negative in some regions of solvent composition and positive in other regions of solvent composition. The negative excess volumes in the binary mixtures of ethyl acetoacetate and the branched ketones are attributed to strong dipole-dipole interactions between unlike molecules while the positive excess volumes are attributed to a mutual loosening of dipole-dipole interactions between like molecules.