FT-IR spectroscopy of nitric acid in TBP/octane solution

Infrared studies for the HNO3/0.73M TBP/n-octane system are reported. Two e xtracted species, TBP . HNO3 and TBP . 2HNO(3), were identified in the orga nic phase. The concentration of the individual species was determined by th e analysis of the vibrational band at similar to 1650 cm(-1). The band at 1 648 cm(-1) was assigned to the monosolvate TBP . HNO3 and the band at 1672 cm(-1) to the hemisolvate TBP . 2HNO(3). The infrared spectra revealed that with respect to the P=O bond, as well to each other, the HNO3 molecules in the hemisolvate are spectrally non-equivalent. The predominant structure o f TBP . 2HNO(3) involves the chain HNO3 dimer. Some ionic NO3- and hydroniu m ions were identified in this system but only during formation of the mono solvate. The analyses performed in this system can serve for the characteri zation of HNO3 in related systems in the presence of metal species.