EXCESS-ENTHALPIES AND EXCESS VOLUMES OF N,N-DIMETHYLETHANOLAMINE PLUS1,4-DIOXANE, PLUS DMF, PLUS DMA OR PLUS DMSO

The excess molar enthalpies of N,N-dimethylethanolamine (DMEA) + 1,4-d ioxane, + DMF, + DMA or + DMSO at 298.15 K have been measured with a P icker microcalorimeter. Excess enthalpies for DMEA with DMF, DMA or DM SO are negative over the entire composition range except for 1,4-dioxa ne. Density measurements were made with an Anton Paar DMA 602 densimet er. Excess volumes of the title mixtures and apparent molar volumes of the components are reported. Excess volumes are all positive. Excess enthalpies and volumes of these systems decrease in the same sequence: 1,4-dioxane > DMA > DMSO > DMF. The observations are discussed in ter ms of hydrogen bonding interactions. (C) 1997 Elsevier Science B.V.