Institute of Theoretical Physics, TU Bergakademie Freiberg, Freiberg, Germany.
J Comput Chem. 2022 Jun 5;43(15):1023-1032. doi: 10.1002/jcc.26865. Epub 2022 Apr 22.
Thermodynamic and kinetic information on the first two steps of gallic acid pyrolysis, a decarboxylation followed by a dehydrogenation, is obtained based on density functional theory and quantum chemistry. For the kinetics, transition states are identified with the help of the climbing image nudged elastic band method. Both reactions exhibit two transition states. One of them is related to the rotation of OH groups, and the other one is related to the breaking and forming of bonds. The gallic acid pyrolysis as a whole is judged to be endothermal, and it changes from endergonic to exergonic between 500 and 750 K. The second reaction, the dehydrogenation of pyrogallol, is identified as the rate-determining step of gallic acid pyrolysis, with reaction rate constants below 1 s for temperatures below 1250 K.
基于密度泛函理论和量子化学，我们获得了没食子酸热解前两步（脱羧和脱氢）的热力学和动力学信息。对于动力学，我们借助 climbing image nudged elastic band 方法确定了过渡态。两个反应都有两个过渡态。其中一个与 OH 基团的旋转有关，另一个与键的断裂和形成有关。总的来说，没食子酸热解是吸热的，在 500 到 750 K 之间从吸能变为放能。第二个反应，焦儿茶酚的脱氢，被确定为没食子酸热解的速控步骤，在 1250 K 以下的温度下，反应速率常数低于 1 s。
