KINETIC INVESTIGATION OF THE SN2 REACTION BETWEEN PIPERIDINE AND CHLOROACETIC ACID USING ATR-FTIR SPECTROSCOPY

In this study, the kinetic characteristics of the nucleophilic substitution (SN2) reaction between piperidine and chloroacetic acid were investigated in real time at 50, 60, and 70 °C using ATR-FTIR spectroscopy. The spectral analysis revealed a gradual decrease in the C–Cl stretching vibration in the 710–730 cm⁻¹ region and a simultaneous increase in absorption bands corresponding to the C–N bond in the 1020–1250 cm⁻¹ region, confirming the consistent progression of the reaction. Analysis of the conversion function X(t) showed values of X = 0.669 at 50 °C, X = 0.826 at 60 °C, and X = 0.970 at 70 °C, indicating a substantial acceleration of the reaction rate with increasing temperature. The dX/dt–t profiles displayed a maximum initial reaction rate followed by exponential decay. Linear regression analysis demonstrated excellent agreement with the first-order kinetic model at all temperatures (R² = 0.97–0.999), and the rate constants increased from 0.0078 → 0.0106 → 0.0143 min⁻¹. Arrhenius analysis yielded an activation energy of 27.9 kJ·mol⁻¹. These results confirm that the piperidine–chloroacetate system proceeds via an SN2 mechanism and demonstrate that ATR-FTIR spectroscopy provides high sensitivity and accuracy for real-time monitoring of reaction processes.

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