Aniline titration curve

The azocompound formed in the coupling reaction between a phenol or aniline derivative and a diazonium salt, is reduced at more negative potentials than the corresponding diazonium salt. If the current is measured at potentials corresponding to the limiting current of the diazonium salt, but more positive than the reduction of the azocompound, it is possible to measure the excess of the diazonium salt from the equivalence point. The resulting titration curve possesses the form given in Fig. 47. 

Diphenylpiperazine can be titrated in acetic anhydride with perchloric acid. The titration curve resulting from plotting millivolts vs. volume of titrant gives two equal and well-defined inflection points. Diphenylpiper-azine is a by-product in the synthesis of diphenylethylene-diamine and may be determined in the presence of the same by acetylation and titration in acetic acid with perchloric acid. It may be identified by separation and titration, obtaining the very characteristic curve in acetic anhydride. Interferences from other tertiary amines and aniline are dealt with in these determinations of diphenylpiperazine. 

W. Lynn Schertz and G. D. Christian, Anal. Chem., 44, 755 (1972). Study of effects of neutral inorganic salts on potentiometrie titration curves of weak bases in nonaqueous solvents. Weak bases used urea, caffeine, Tw-nitroaniline, iV-dimethylaniline, aniline and pyridine. Solvents acetone, methyl isobutyl ketone, 2-butanone. Solutes LiC104, Lil, Mg(C104)2. 

---