4-乙酰基-1,3-二氟苯硝化反应机理研究

Theoretical study on initiated reaction mechanism of nitration of 4-acetyl-1,3-difluorinbenzene

以4-氨基-1,3-二氟苯、乙酸酐和浓硝酸等为原料,合成了4-乙酰基-5-硝基-1,3-二氟苯,并且采用FTIR和1H NMR对产物进行了表征.采用量子化学方法,探讨了在酸催化条件下4-乙酰基-1,3-二氟苯硝化反应过程中的微观机理,在密度泛函理论的B3LYP/6-311G**水平下搜索得到反应路径,并对各中间体、过渡态和产物进行几何优化、振动频率分析和标准热力学函数计算;反应路径经过IRC验证.在MP2/6-311G**水平上对所有中间体、过渡态和产物进行更精确的能量计算.

On the basis of experimental synthesis of 4-acetyl-5-nitro-1,3-difluorinbenzene by using acetic anhydride, concentrated nitric acid and 4-amido-1,3-difluorinbenzene, the mechanism of initiated reaction of nitration of 4-acetyl-1,3-difluorinbenzene has been studied. In details, the reaction pathway was investigated by Density Functional Theory （DFT） method at the B3LYP/6-311G^＊＊ level. The geometry configurations of reactant, product, intermediates,and transition states were fully optimized,and the intermediates and transition states were verified by the frequency analysis and confirmed by intrinsic reaction coordinate （IRC） calculations. The energy was corrected at the 6-311G^＊＊ level using the more accurate MP2 method. Activation energy of the electrophilic substitution was 18.36 kJ/mol.