As the mechanisms of the hydride transfer reaction between 7,8-dihydro-9-methylcaffeine (CAFH) with N-methylacridinium (AcrH⁺ClO₄^-) and hydrogen atom transfer (HAT) reaction between 2,3-dihydrobenzo-imidazoles (BIH) with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•) were researched to both be induced by electron transfer, the reaction mechanisms of 2,3-dihydrobenzo-thiazoles (BTH) with these two substrates were studied. The thermodynamic analysis platforms were used to judge the mechanisms, and the mechanisms of these two reactions were not the same with CAFH and BIH as the E_ox (BTH) value was more positive than CAFH and BIH. A new method for inferring the reaction mechanism was proposed using the kinetic equation ΔG^≠_XH/Y = ΔG^≠o (XH) + ΔG^≠o(Y) and thermo-kinetic parameter ΔG^≠o. The HAT reaction mechanisms between BTH with DPPH^• and ^tBu₃PhO^• were researched by ΔG^≠o_HD. As the ΔG^≠o (BTH) values in these two reactions were similar; hence, the rate determining steps of them were both HATs as the ΔG^≠o_HD(Y) values of DPPH^• and ^tBu₃PhO^• used for determining ΔG^≠o (BTH) were both in HAT reactions. The HAT reaction mechanisms between BIH with ^tBu₃PhO^• were also researched by thermodynamic analysis platform and kinetic isotope effect (KIE = 3.99), which confirmed that the rate determining step of BIH/^tBu₃PhO^• was indeed HAT. The H-donating ability of BIH and BTH was compared by ΔG^≠o_HD. From BIH to BTH, the substitution of N by S not only greatly reduces the thermodynamic electron donating and H-donating capacity of the compound but also increases the H-donating ability in kinetics and HAT reaction.

中文翻译：

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N、S原子对五元含氮杂环氢转移机制的影响

作为7,8-二氢-9-甲基咖啡因（CAFH）与N-甲基吖啶鎓（AcrH ⁺ ClO ₄ ^-）之间的氢化物转移反应和2,3-二氢苯并咪唑（BIH）之间的氢原子转移（HAT）反应的机理）与2,2-二苯基-1-三硝基苯肼自由基（DPPH ^•）均通过电子转移诱导，研究了2,3-二氢苯并噻唑（BTH）与这两种底物的反应机理。利用热力学分析平台判断其机理，这两个反应的机理与CAFH和BIH并不相同，因为E ox ₍ BTH)值比CAFH和BIH更正。利用动力学方程 Δ G ^≠ _XH/Y  = Δ G ^≠o (XH) + Δ G ^≠o (Y) 和热动力学参数 Δ G ^≠o ，提出了一种推断反应机理的新方法。通过Δ G ^≠o _HD研究了BTH与DPPH ^•和^t Bu ₃ PhO ^•之间的HAT反应机理。由于这两个反应中的 Δ G ^≠o (BTH) 值相似；因此，它们的速率确定步骤都是HAT，因为DPPH ^•的ΔG ^≠o _HD (Y)值和用于确定ΔG ^{≠o (BTH)的t} Bu ₃ PhO ^•都在HAT反应中。^{利用热力学分析平台和动力学同位素效应（KIE = 3.99）研究了BIH与t} Bu ₃ PhO ^•之间的HAT反应机理，证实了BIH/ ^t Bu ₃ PhO ^•的速率决定步骤确实是HAT。BIH和BTH的供氢能力通过ΔG ≠ ^o _HD进行比较。从BIH到BTH， N被S取代不仅大大降低了化合物的热力学供电子和供氢能力，而且增加了动力学和HAT反应中的供氢能力。