SINGLE ION ENTHALPIES OF TRANSFER FROM METHANOL TO DIMETHYL SULFOXIDE, N,N-DIMETHYLFORMAMIDE, N-ETHYLACETAMIDE, AND N-METHYLPYRROLIDINONE

Enthalpies of solution (ΔH3,) of 16 organic and inorganic salts have been measured in methanol, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-methylpyrrolidinone (NMP), N-ethylacetamide (NEA), and water, and of the lithium halides in hexamethylphosphoric triamide (HMPT). Single ion enthalpies of transfer (δΔH3,) from methanol to the other solvents have been calculated on the basis of three different extra-thermodynamic assumptions: ΔΔH3((C4H9)4N+) = ΔΔH8(−B(C4H9)4), ΔΔH3((C5H11)4N+) = ΔΔH5(_B(C5H11)4), and δδH8((C6H5)4AS+) = δδH3(−B(C6H5)4). There is good agreement in all cases between single ion enthalpies of transfer calculated from the first two assumptions, but values based on the tetraphenylarsonium tetraphenylborate assumption show deviations. Some δH3, values in the solvents water, methanol, DMF, and NEA are concentration dependent and have been extrapolated to zero concentration. The present values of δH3, (at c = 0) for (C4H9)4NB(C4H9)4 in methanol and DMF are quite different from some recently reported values12 measured at higher concentrations. © 1969, American Chemical Society. All rights reserved.