【作者】 孙德升；

【导师】 王遵尧； 杨春生；

【作者基本信息】 南京工业大学 ， 化学工程， 2006， 硕士

【摘要】 卤素互化物在有机合成和化学分析领域中有着重要的作用,本论文从理论和实验两方面对合成卤素互化物（BrCl、IBr、ICl）的反应进行了研究。在理论研究部分,用量子化学中的密度泛函（DFT）方法对Br₂+Cl₂=2BrCl、Br₂+I2=2IBr和I2+Cl₂=2ICl的气相反应机理进行了计算研究,对含碘元素的反应取3-21G**基组,其它反应均取6-311G**基组。获得如下结果和结论:（1）在无外界能量提供的条件下,气相反应Br₂+Cl₂=2BrCl、Br₂+I2=2IBr和I2+Cl₂=2ICl将优先以双分子作用形式完成。（2）双分子的基元反应都有多种构型的四中心过渡态,在这些四中心过渡态中,以“Z”形过渡态较稳定,所有的四中心过渡态都呈平面构型。（3）反应Cl₂+Br→BrCl+Cl和反应I+Cl₂→ICl+Cl的活化能分别为19.09 kJ/mol和6.12kJ/mol;反应Cl₂+Br→BrCl+Cl、I+Br₂→IBr+Br、I2+Br→IBr+I、I2+Cl→ICl+I是经过无垒过程生成较稳定的三原子分子（Br₂Cl、I2Br IBr₂和I2Cl）,之后再经能量逐渐升高并趋于平缓的过程,分解为产物。在实验研究部分,将氯、溴、碘分别配成相同浓度的四氯化碳溶液,再等体积混合,分别在光照和避光条件下反应,每隔一定的时间用紫外-可见分光光度计测定混合溶液的吸光度,实验结果表明:在避光条件下,反应Br₂+Cl₂=2BrCl、Br₂+I2=2IBr和I2+Cl₂=2ICl较光照条件下反应的慢,说明光照使Cl₂、Br₂和I2首先裂解成原子,再与另一反应分子经过三中心过渡态形成产物,因此,光照条件下的反应速度较快。因此,通过对气相反应Br₂+Cl₂=2BrCl、Br₂+I2=2IBr和I2+Cl₂=2ICl的理论和实验研究得到相同的结论:在无光照引发和无外界能量提供的条件下将优先以分子与分子作用形式完成反应;在光照条件下反应物将首先裂解成自由基,经过自由基反应很快完成反应。更多还原

【Abstract】 Interhalogen compounds play an important role in the organic synthesis and chemistry analysis field. This dissertation mainly includes theory research and experiment research for the interhalogen compounds（BrCl、IBr and ICl）.For the theory research part, the density functional theory （DFT） in the quantum chemistry has been employed to investigate the gas reaction mechanism particularly for Br₂+Cl₂=2BrCl, Br₂+I2=2IBr and I2+Cl₂=2ICl. The 3-21G** basis set has been employed for iodine-containing reactions and the 6-311G** basis set for other reactions. The following results and conclusions have been reached: （1） Reactions Br₂+Cl₂=2BrCl, Br₂+I2=2IBr and I2+Cl₂=2ICl occur more easily in the bimolecular form without energy. （2） The bimolecular elementary reactions have different four-center transition states. Among these four-center transition states, the transition state with“Z”form is the most stable. All the four-center transition states are planar. （3） The active energy for the reactions Cl₂+Br→BrCl+Cl and I+Cl₂→ICl+Cl is 19.09 and 6.12KJ/Mol; and for the reactions Cl₂+Br→BrCl+Cl, I+Br₂→IBr+Br, I2+Br→IBr+I, I2+Cl→ICl+I take place first via processes without energy barrier to form stable molecules BrCl₂, IBr₂, I2Br and I2Cl, then the energy of systems increase steadily and the molecules decompose to products.For the experiment research part, the chlorine, bromine and iodine were prepared carbon tetrachloride solution in the same concentration, and then the same volume solution were mixed respectively, these mixed solutions were put under the ultraviolet radiation and in the dark respectively. The absorbency of the mixed solutions was determined with UV spectrophotometer every determinate time. The experiment results show: the reaction rate for the gas reactions Br₂+Cl₂=2BrCl, Br₂+I2=2IBr and I2+Cl₂=2ICl in the dark is slower than that with ultraviolet radiation; which indicated that Cl₂、Br₂ and I2 are split into free radicals firstly, and then this free radical reacts with another molecule through a three-center transition state to form the product, so the reaction rate is rapid when the ultraviolet radiation exists.So, the same conclusions can be achieved by the theory research and experiment更多还原