EFFICIENT SYNTHESIS OF LONG-CHAIN SUBSTITUTED VINAMIDINIUM SALTS - POSITIVE SALT EFFECT

A series of 1,5-Diaza-1,5-diaryl-1H-pentadienium salts with mesogenic substituents have been synthesized. A positive salt effect is observed (an increase in the yield and reaction rate) in acetic acid/lithium tetrafluoroborate (or sodium tetrafluoroborate) medium. 3,4-dialkoxy and 3,4,5-trialkoxyanilines were prepared from 1,2-dialkoxy and 3,4,5-trialkoxybenzenes. A biphasic nitration process gives 3,4-dialkoxy and 3,4,5-trialkoxybenzenes, respectively. Reduction by hydrazine/graphite then leads to the corresponding anilines in high yields.