RAMAN-SPECTROSCOPIC STUDY OF THE ASSOCIATION BETWEEN ACRYLONITRILE AND NICKEL(II) IN AQUEOUS-SOLUTION - ESTIMATION OF THE ENTHALPY OF ASSOCIATION

The association between acrylonitrile (CH2=CH-CN) and the Ni2+ ion in aqueous solution was studied by Raman spectroscopy. A new band at about 2284 cm(-1) in the region of the upsilon(CN) fundamental was observed and attributed to cation-associated acrylonitrile. Spectra were taken in a temperature range of 248 to 338 K, and for a range of concentrations of 1.27-4.30 m for nickel (as nickel(II) nitrate) and 2.32-3.37 m for acrylonitrile. The wavenumber of the new band was independent of the temperature and concentration, which indicates that the stoichiometry of the association does not change over the range of experimental conditions studied. For a 1:1 (nickel:acrylonitrile) molar ratio in the associated species, the enthalpy of the association was estimated as -6.15 +/- 0.24 kJ mol(-1).