The Complexing of the Sodium Ion in Acetonitrile with Other Solvents. Investigation by the Use of a Cationsensitive Glass Electrode

The complexing of the sodium ion in acetonitrile (AN) with such solvents as methanol, water, DMF, DMA, DMSO, HMPA, and pyridine has been studied potentiometrically by using a monovalent cation-sensitive glass electrode. The reference electrode of Ag-0.005 M AgNO3(AN) and the salt bridge of 0.1 M Et4NPi(AN) were used. Mono- and di-solvated ions were formed for methanol, water, and pyridine. For DMF, DMA, DMSO, and HMPA, tri-solvated species were also formed. The formation constants for the mono-solvated sodium ion were 0.7 for pyridine, 1 for methanol, 1.8 for water, 2.5 for DMF, 5 for DMA, 6 for DMSO, and 30 for HMPA.