Abstract: Infrared spectra of binary mixtures of aniline or N-methylaniline with n-heptane, carbon tetrachloride, benzene or toluene have been measured at room temperatures with an IR spectrometer. The solvent effect on the NH group stretching vibration frequencies were discussed. Infrared spectra of several mixtures containing a nitro-genous Lewis base in CCl_4. were also determined and the involved cross-association contants were calculated. The results indicate that aniline is a stronger proton donor than N-methylaniline when they associate with pyridine in CCl_4, and the protonaccepting ability of several bases increase in the order: aniline ～N-methylaniline

Key words: Infrared spectrum, Solvent effect, Hydrogen bonding, Association equilibrium constant