SPECTROPHOTOMETRIC STUDIES OF SOME BIS-AZO-BETA-DIKETONE COMPOUNDS AND THEIR IONIZATION-CONSTANTS IN MIXED BUFFER SOLUTIONS

A series of bis-azo compounds have been prepared from m- and p-phenylenediamine and beta-diketones. The electronic absorption spectra of the compounds have been studied in organic solvents of different polarities. The effect of medium on band position and band assignment has been considered. The ir and H-1 nmr spectra are discussed in relation to molecular structure. The spectral changes in buffer solution of pH congruent-to 2-12 were used for calculating the pK(a) values of the bis-azo compounds under study.