SPECTROPHOTOMETRIC STUDY OF THE REACTION BETWEEN HYDRAZINE AND P.DIMETHYLAMINOBENZALDEHYDE

In order to realize an optical fibre chemical sensor for hydrazine in the Purer process, the reaction between hydrazine and p.dimethylaminob enzaldehyde (p.DMAB) in nitric acid medium was studied by spectrophoto metry and H-1.NMR. The effect of temperature and acidity were determin ed. The equilibrium constant is of 7,800l/mol at 15 degrees C and decr eases to 600 at 55 degrees C. The reaction is fully reversible. In ord er to keep p.DMAB out of damage, the acidity working range has to be w ithin 0.1 to 1.0 M in nitric acid medium. This reaction is suitable fo r the application of optical fibre chemical sensors because direct rev ersibility or regeneration by temperature or acidity may be possible.