Novel Schiff Bases Derived From Pyromellitic Dianhydride

Abstract

   The new Schiff bases derived from pyromellitic dianhydride were   synthesized  by  several  steps  reaction . A symmetrical  diamic acide  [I ]a-c  were  synthesized  by  the  reaction  of  pyromellitic  dianhydride  with  some aromatic  amines  (containing  electron  withdrawing , repulling  groups ) in dry acetone.      In the second step the  diacids were converted  to  their corresponding  diimide [II ]a-c using acetic anhydride and sodium acetate system as a dehydrating agent,    via  the  intra molecular  cyclization  steps  of  amic  acids.     The  third  step  was  to  synthesize  the  hydrazone  derivatives from  the  reaction  of  diimides  ,   with  80 % hydrazine  hydrate  at  (50-60)CËš .       These  hydrazone derivatives were allowed to  react  with several  aromatic  aldehydes to form new  Schiff  bases  via  step  four  at a temperature  near by   (50)CËš .      All  the  novel  compounds  and  their  structures  have  been  ascertained  by their  melting  points , mixed melting  points , C .H . N  analysis , FTIR  spectroscopy  and  HNMR  for  some  of  them .