抄録
Studies were made on the interaction of 4-nitroquinoline 1-oxide with phenol and its methyl substituted derivatives in solution, and simultaneous participation of charge transfer and hydrogen bonding was deduced. New absorption bands were observed in the visible difference spectra of mixed systems of phenols and the N-oxide compound, which were ascribed to π-π* transitions. From the analysis of the difference spectra it was revealed that 1 : 1 complexes were formed, and the values of λmax, ε, K, and ΔH were determined. The participation of π-π type charge transfer was indicated by the following results. (1) A linear relationship was found between ET values for the phenol-4-nitroquinoline 1-oxide complex and Z values of solvents. (2) Corresponding relationships were found between ID values of phenols and the hv values of complexes formed between phenols and 4-nitroquinoline 1-oxide in carbon tetrachloride. (3) Examination of K values revealed that the complex formation is hindered by multiple substitution of methyl groups into the benzene ring of phenol. Participation of hydrogen bonding in this interaction was demonstrated by the smallness of K value in the mixed system of anisole as compared with that of the mixed system of phenol and also by the lower frequency shift of the O-H stretching band of phenol caused by the addition of the N-oxide compound. Possible conformation of the phenol-4-nitroquinoline 1-oxide complex was proposed.
