A near infrared and NMR spectroscopic study of the solvation of basic aprotic solvents and anions in tert-butanol

The near infrared (NIR) spectrum for pure tert-butanol shows an intense, very narrow feature at 7062 cm(-1) which is close to the band for dilute solutions in carbon tetrachloride and for the monomer in the gas phase. When basic aprotic solvents such as dimethylsulfoxide or cyanomethane are added, the intensity of this (OH)(free) band falls to low values. Similar behaviour is observed for added tetraalkylammonium salts. These results are discussed in terms of the scavenging of (OH)(free) groups by these additives. They are compared with results of similar studies using methanol and water and hence estimates of the active solvation numbers are derived. NIR is also used to help interpret H-1 NMR studies of the O-H protons in the systems.