氟氯酰与正癸烷反应的瞬态光谱和机理探索研究

Instantaneous Emission Spectra and Mechanism Study on the Reaction of ClF_(3)O and n-Decane

氟氯酰(ClF_(3)O)是一种极强的氟化剂和氧化剂,极易与水和有机物发生爆炸性反应。目前关于氟氯酰与水以及有机物等物质的反应机理不多见,氟氯酰与水以及有机物等物质由反应物变成产物的过程有待研究。采用ICCD瞬态光谱测量系统,实时拍摄到无氧和有氧环境下氟氯酰和正癸烷反应的瞬态发射光谱;采用量子化学理论方法对氟氯酰和正癸烷的反应机理进行了探索研究,理论计算与试验结果相一致。瞬态发射光谱试验结果表明,在无氧环境下,氟氯酰和正癸烷反应会产生CH和C_(2)自由基,证实了无氧时氟氯酰确实能与正癸烷发生反应,显示出氟氯酰的高活性;在有氧环境下,则会产生OH,CH和C_(2)自由基。CH自由基强度最大的发射峰位于431.4nm,归属于A^(2)Δ-X^(2)П电子态之间的跃迁;C_(2)自由基强度最大的发射峰位于516.3nm,归属于A^(3)П_(g)-X^(3)П_(u)电子跃迁;OH自由基强度最大的发射峰位于309.5nm,归属于A^(2)Σ+-X^(2)П_(i)电子跃迁。量子化学理论计算结果表明,ClF_(3)O与正癸烷的反应始于ClF_(3)O中具有较多负电荷的F原子向正癸烷分子中间的H原子进攻生成HF,该引发反应活化能很低,并大量放热。在无氧环境下,氟氯酰与正癸烷可能发生氟代反应,反应产物为ClFO、HF和相应的氟代烷烃等。氟代烷烃可能会发生脱氢反应生成C_(10)H_(20)F,接着裂解为C_(4)H_(9)及氟代烯烃C_(6)H_(11)F;C_(4)H_(9)进一步分解为C_(2)H_(5)和C_(2)H_(4),最终形成CH和C_(2)自由基等。有氧环境下反应初始步骤与无氧条件下相同,当反应进行到一定程度,产生烷烃自由基之后,O_(2)参与反应,形成过氧自由基,过氧自由基继续分解,产生OH,CH和C_(2)自由基。在氧气参与下,反应过程中产生大量的OH自由基,加速反应的进程,宏观上表现为正癸烷被引发爆燃与燃烧。这些自由基和中间体对于揭示氟氯酰和正癸烷反应的微观机理具有重要的指示意义。氟氯酰和正癸烷的反应机理与试验结果均证实:小自由基CH、OH和C_(2)是氟氯酰与正癸烷反应过程中的重要中间产物,这对于认识氟氯酰与正癸烷反应的微观过程非常重要,也为氟氯酰的武器化应用奠定了一定的理论基础。

Chlorine trifluoride oxide(ClF_(3)O)has stronger corrosive and oxidizing properties than other chlorine fluorides such as ClF_(3).It can react with numerous materials,e.g.,water and hydrocarbons.The reaction between ClF_(3)O and organic hydrocarbons may occur at quite a low temperatures and cause an explosion.So far,however,no detailed information about the reactions is available.Using an intensified charge-coupled device(ICCD)system,transient emission spectra of the reaction of ClF_(3)O and n-decane were measured in a spectral range of 200~850 nm.Using density functional theory(DFT)method were performed to investigate the reaction mechanism of ClF_(3)O and n-decane.All calculated results are consistent with the experimental data,which indicates that the present results are credible.The emission spectra of CH and C_(2) radical intermediates were observed in the reactions of ClF_(3)O and n-decane under a no-oxygen environment,and this shows that ClF_(3)O is a highly reactive compound.The detection of the CH,C_(2) and OH radical intermediates shows clearly that a large amount of energy was released during the reaction between ClF_(3)O and n-decane under an oxygen environment.The primary peak was found at 431 nm corresponding to theA^(2)Δ-X^(2)Πelectronic transition of the CH radical.The peak at 516 nm produced by theA^(3)П_(g)-X^(3)П_(u) electronic transition of the C_(2) radical was also observed.The peak at 309 nm corresponds to theA^(2)Σ+-X^(2)П_(i) electronic transition of the OH radical was also found.The results of the calculations showed that the F atom on ClF_(3)O attacks the H atom on n-decane to initialize the reactions,and a F atom on ClF_(3)O abstracted h atom on n-decane to produce HF.The initial reactions were considered to be barrier-less reactions and extremely exothermic.Under a no-oxygen environment,a fluorination reaction occurred between ClF_(3)O and n-decane,and the products were ClFO,HF and corresponding fluoroalkanes.Fluoroalkanes may undergo dehydrogenation to form C_(10)H_(20)F.Then it is cleaved into C_(4)H_(9 )and C_(6)H_(11)F,then C_(4)H_(9) further decomposed into C_(2)H_(5) and C_(2)H_(4),and finally formed CH and C_(2) radical.The initial steps of reaction in the aerobic environment were the same as in an anaerobic condition.When the reaction proceeded to a certain degree,after producing alkane radicals,O_(2) formed peroxic radicals,and peroxic radicals continue to decompose to form CH,C_(2) and OH radical intermediates.In the presence of oxygen,many OH radicals were produced in the reaction process,which accelerated the process of reaction.Macroscopically,n-decane was initiated by deflagration and combustion.Results show that the main emission bands are attributed to OH,CH and C_(2) radicals produced during the reaction process of ClF_(3)O and n-decane,which reveals that small OH,CH and C_(2) radicals are important intermediate products in the reaction process of ClF_(3)O and n-decane.This is very important for understanding the micro-process of reaction of ClF_(3)O and n-decane.It also play an important theoretical foundation for the application of the weapon of ClF_(3)O.