苯并氧化呋咱稳定性和异构化的DFT和ab initio研究

运用B3LYP/6-31G(d)密度泛函理论（DFT）方法对苯并氧化呋咱、邻二亚硝基苯及其间的异构化反应进行了计算研究。结果表明,苯并氧化呋咱的分子总能量比邻二亚硝基苯的低;由苯并氧化呋咱异构为邻二亚硝基苯的正向反应活化能（Ea+=51.0kJ/mol）,与文献实测值（58.6kJ/mol）较接近,而其逆向反应活化能（Ea-=4.6kJ/mol）很小,从而揭示了苯并氧化呋咱比邻二亚硝基苯更稳定·此外,进行了HF/3-21G、HF/6-31G(d)和MP2/6-31G(d)//6-31G(d)水平下相应的计算,发现B3LYP-DFT的结果较abinitio为优。谐振动频率的B3LYP/6-31G(d)计算还支持了邻二亚硝基苯为苯并氧化呋咱“自-自”互变重排反应的中间体。     

One-pot methodology for conversion of o-halogen nitrobenzenes to benzofuroxans

Reaction of o-halonitrobenzenes with sodium azide under reflux of DMF/H₂O gives benzofuroxans in one step in moderate to good yields. This is a faster methodology compared to the conventional procedure involving the preparation and subsequent pyrolysis of o-nitrophenyl azides. For comparison, the reaction was also performed under phase-transfer catalysis.     

苯并氧化呋咱稳定性和异构化的DFT和ab initio研究

运用B3LYP/6-31G(d)密度泛函理论（DFT）方法对苯并氧化呋咱、邻二亚硝基苯及其间的异构化反应进行了计算研究。结果表明,苯并氧化呋咱的分子总能量比邻二亚硝基苯的低;由苯并氧化呋咱异构为邻二亚硝基苯的正向反应活化能（Ea+=51.0kJ/mol）,与文献实测值（58.6kJ/mol）较接近,而其逆向反应活化能（Ea-=4.6kJ/mol）很小,从而揭示了苯并氧化呋咱比邻二亚硝基苯更稳定·此外,进行了HF/3-21G、HF/6-31G(d)和MP2/6-31G(d)//6-31G(d)水平下相应的计算,发现B3LYP-DFT的结果较abinitio为优。谐振动频率的B3LYP/6-31G(d)计算还支持了邻二亚硝基苯为苯并氧化呋咱“自-自”互变重排反应的中间体。     

2-硝基苯胺合成苯并氧化呋咱反应的密度泛函研究

用密度泛函理论在B3LYP/6-31G(d,p)计算水平下研究了次氯酸钠氧化邻硝基苯胺生成苯并氧化呋咱的环氧化反应．考虑溶剂化效应对反应的影响,使用极化连续反应场模型进行几何优化．计算了该反应的两种可能反应通道,它们都是分步反应,反应通道A经历氧化、移氢、脱水和环化四步反应,在反应通道B中,氢氧化钠的OH^-首先进攻邻硝基苯胺的胺基H原子,生成邻硝基苯亚胺负离子．计算结果表明,在反应通道A是可行的反应通道,1个水分子辅助进行分子内脱水反应是速控步骤．     

DFT Study of Benzofuroxan Synthesis Mechanism from 2-Nitroaniline via Sodium Hypochlorite

The oxidative cyclization reaction of 2-nitroaniline via sodium hypochlorite to yield benzo-furoxan is investigated by the hybrid density functional theory B3LYP/6-31G(d,p) method. Solvent effects are estimated with the polarizable continuum model to optimize structures. The title reaction is predicted to undergo two pathways, each of which is a stepwise process.Path A includes four steps, namely oxidization, H-attack, hydrolysis, and cyclization. Path B involves the nucleophilic attack of OH^- to the H atom of the N-H bond and the proton transfer to the N atom of amino group leading to the cleavage of the N-H single bond in the amino group. The calculated results indicate that path A is favored mechanism for the title reaction. Furthermore, it is rational for one water molecule serving as a bridge to assist in the hydrolysis step of Path A and our calculations exhibit that this process is the rate-determining step.