高等学校化学学报
高等學校化學學報
고등학교화학학보
Chemical Journal of Chinese Universities
2015年
10期
1954-1960
,共7页
叔丁氧基自由基%氢迁移过程%溶液中自由能%反应速率常数
叔丁氧基自由基%氫遷移過程%溶液中自由能%反應速率常數
숙정양기자유기%경천이과정%용액중자유능%반응속솔상수
t-Butoxyl radical%Hydrogen abstraction%Free-energy barriers in solution%Rate constant
采用多种密度泛函理论方法(如 CAM-B3LYP, M062x 和 wB97x 方法),并辅以极化连续介质模型对叔丁氧基自由基( t BuO·)与一系列胺类、烷烃、醇类和醚类反应物之间氢迁移反应的反应机理进行研究。计算结果表明,这类氢迁移反应主要受熵的控制。通过对液相平动熵和气相平动熵得到的活化自由能数据进行对比,可以看出,使用气相平动熵得出的活化自由能明显偏高于实验测量值,而以液相平动熵计算的反应活化自由能垒与实际结果相近,3种方法对胺类和烷烃类反应物体系得出的结果更可靠,对醇类和醚类反应物体系自由能垒则略低。
採用多種密度汎函理論方法(如 CAM-B3LYP, M062x 和 wB97x 方法),併輔以極化連續介質模型對叔丁氧基自由基( t BuO·)與一繫列胺類、烷烴、醇類和醚類反應物之間氫遷移反應的反應機理進行研究。計算結果錶明,這類氫遷移反應主要受熵的控製。通過對液相平動熵和氣相平動熵得到的活化自由能數據進行對比,可以看齣,使用氣相平動熵得齣的活化自由能明顯偏高于實驗測量值,而以液相平動熵計算的反應活化自由能壘與實際結果相近,3種方法對胺類和烷烴類反應物體繫得齣的結果更可靠,對醇類和醚類反應物體繫自由能壘則略低。
채용다충밀도범함이론방법(여 CAM-B3LYP, M062x 화 wB97x 방법),병보이겁화련속개질모형대숙정양기자유기( t BuO·)여일계렬알류、완경、순류화미류반응물지간경천이반응적반응궤리진행연구。계산결과표명,저류경천이반응주요수적적공제。통과대액상평동적화기상평동적득도적활화자유능수거진행대비,가이간출,사용기상평동적득출적활화자유능명현편고우실험측량치,이이액상평동적계산적반응활화자유능루여실제결과상근,3충방법대알류화완경류반응물체계득출적결과경가고,대순류화미류반응물체계자유능루칙략저。
The reaction mechanisms of hydrogen abstractions from carbon by the t-butoxyl radical were investi-gated with several density functional theory(DFT) methods, such as CAM-B3LYP, M062x and wB97x. The results show that most of these reactions are dominated more by entropic than by enthalpic factor. The activation free energy barriers were calculated with both gas-phase translational entropy and solution transla-tional entropy, in which those from ideal gas-phase translational entropy(output of Gaussian job) were much higher than the experimental estimations. It has been verified that free-energy barriers of amines and hydrocar-bons reactions generated from solution translational entropies are close to the experimental measurements, but all these methods predict a little low free-energy barriers for alcohols and ethers reactions.
