RAMAN-SPECTROSCOPIC STUDY OF COMPLEX-FORMATION BETWEEN P-CRESOL AND PROPIONITRILE

Raman spectroscopy, together with factor analysis and band resolution techniques, was used to study complex formation in binary mixtures of p-cresol and propionitrile in the concentration range 0.025-0.651 mole fraction of p-cresol. The envelope of the C=N stretching band of prop ionitrile in the Raman spectrum between 2300 and 2200 cm(-1) was studi ed. Factor analysis indicated that there were only two linearly indepe ndent components in the band envelope. The appearance of a pseudo-isos bestic point in the area normalized spectra supported this conclusion. For all concentrations, the C=N stretching band envelope was resolved into three components. These were assigned in turn to the free propio nitrile, a 1:1 p-cresol-propionitrile complex and an overtone or combi nation mode of propionitrile which does not involve C=N stretching, Th e equilibrium constant K-c for the formation of the complex was determ ined at various mole fractions of p-cresol. The calculated values of K -c exhibited a strong concentration dependence.