Experimental and theoretical investigation of the structure and nucleophilic properties of 4-aminocoumarin

Abstract

4-Aminocoumarin 2 was prepared in high yield via solventless reaction. The structure of the 2 was determined with single crystal X-ray analysis. The detailed NMR and IR spectra were reported for the first time. DFT calculations [B3LYP/6-31+G**] showed good agreement between the theoretical and experimental values for the optimized and X-ray structures, as well as between the vibrational and NMR spectroscopy. The thermodynamic pKBH+ values were calculated using three different methods: Yates and McClelland (with HA acidity functions), Excess Acidity Method and Bunnett and Olsen Method. The experimental and theoretical data presented are consistent with the weak nucleophilic properties of 2.