SPECTROPHOTOMETRIC DETERMINATION OF AROMATIC-ALDEHYDES BASED ON THEIRCONDENSATION WITH 3-METHYL-1-PHENYLPYRAZOLIN-5-ONE - A COMPARATIVE KINETIC-STUDY

The condensation reaction of 3-methyl-1-phenylpyrazolin-5-one with ben zaldehyde and some substituted benzaldehydes in chloroform medium and in the presence of piperidine has been investigated spectrophotometric ally at 30-45 degrees C. The reaction follows overall second order kin etics, first order in each of the reactants and zero order with respec t to piperidine. The rate of condensation decreases with the presence of electron withdrawing groups and increases with electron donating gr oups on the aromatic ring of the aldehyde. Based on this reaction, det ermination of five aromatic aldehydes in a concentration range of 0.01 -0.1 mM is proposed.