A New Synthesis of the Schiff Base Derived from 2, 3, 4- Trihydroxybenzaldehyde and 4-Aminobenzoic Acid via Airflow Grinding Technology

Abstract Exploring a new reaction system is necessary to widen the application of supersonic speed airflow grinding technology in chemical filed. In this work, the supersonic speed airflow grinding instrument was firstly improved via adding the microwave technology. And then the improved instrument was used to try to synthesize a Schiff base derived from 2, 3, 4- trihydroxybenzaldehyde and 4-aminobenzoic acid, and the molecular structure of synthesized Schiff base was characterized by 1 H nuclear magnetic resonance and fourier transform infrared spectrometer. Finally the geometric structure of synthesized Schiff base was optimized by DMol3 density functional theory. The relevant results showed that the airflow grinding technology was a feasible method to synthesize the Schiff base, and HOMO and LUMO of optimized Schiff base were -0.197684 eV and -0.096761 eV, respectively. Additionally, the theoretical calculation further showed that, with increasing of temperature, the entropy, heat capacity and enthalpy of Schiff base increased, but the free energy decreased.