The polarographic reduction of some a r y l i d e n e s a l i c y l i c h y d r a z i d e s a t a mercury e l e c t r o d e was s t u d i e d i n u n i v e r s a l b u f f e r s o l u t i o n s contain-
ZPP,gP ethanol. The mechanism of t h e e l e c t r o d e procesBes corresponding t o t h e observed cathodic wave is reported. The e f f e c t o f s u b s t i t u e n t group on t h e half-wave p o t e n t i a l has a l s o been discussed. The values of t h e k i a e t i o parameters for t h e e l e c t r o d e r e a c t i o n at d i f f e r e n t pH values axe computed using t h e Routecky and Ilalahay equations. INTRO LXJCTION The reduction of carbonyl compounds' (l;2) and azomethine derivatives(3-6) was t h e subject o f many i n v e s t i g a t i o n s , but few polarographic s t u d i e s (7-10) has been conducted with t h e compounds containing both ;C=O and >C=N linkages.
In t h i s context, T r i o u f l e t (6) observed a & e l e c t r o n mechanism f o r t h e pola- rographic reduction o f benzaldehyde thiosemicarbazone i n a c i d s o l u t i o n e . The polarographic reduction of benzaldehyde, benzophenone and p-aminoacetophenone aemicarbazones showed a s i n g l e pH-dependent wave i n a c i d medium, tbe height of t h e wave diminshed with i n c r e a s i n g t h e pH (3), t h e r e a c t i o n consumed 4 and