Kinetic evaluation of an oligomeric amidation reaction

Homopoly(amides) similar to those of liquid crystalline poly(oxybenzoate) were prepared by acidolysis of the monomer p-acetamidobenzoic acid. The kinetics of catalyzed and uncatalyzed acidolysis of the 4-acetamidobenzoic acid were investigated at 265, 275, and 285 degreesC. A second-order rate model, which can analyze kinetic parameters of two different kinetic regimes, was used to interpret the experimental data for 18 different experimental sets. It is observed that the correlation coefficient between observed and calculated values range between 0.98 and 0.99, confirming the validity of the stated model. The nature of the kinetic behavior in the two regimes was found to be independent of both catalyst type and concentration. In effect second-order rate law adequately describes the entire kinetic behavior of this system. The Arrhenius constants and activation energy parameters for this system have been reported. Differential scanning calorimetry (DSC) results of the oligomers indicate that the homopoly(amides) melt around 360 degreesC with degradation. (C) 2001 John Wiley & Sons, Inc.