Lupi Jacopo, Ballotta Bernardo, Ayarde-Henríquez Leandro, Dooley Stephen
CNR-ICCOM, Consiglio Nazionale Delle Ricerche, Pisa, Italy.
School of Physics, Trinity College Dublin, Dublin, Ireland.
J Comput Chem. 2025 Jun 15;46(16):e70151. doi: 10.1002/jcc.70151.
This study unveils a new transition state (TS) leading to the acyclic product via synchronous double proton transfer by automatedly exploring the potential energy surface of -D-xylopyranose under pyrolysis conditions. Quantum chemistry methods with multi-path canonical variational transition state theory show that the standard activation enthalpy of the new TS (44.9 kcal ) is 1.5 kcal lower than that of the well-established channel; however, the latter's rate constant ( - ) is higher in the 673.15-873.15 K pyrolytic range by a factor of 5-8. This gap narrows to a factor of 2 within 320-400 K, signifying that the new TS can potentially impact the acyclic product production in this low-temperature regime. This is particularly relevant for -D-xylopyranose trimers, as the interior unit bears different substituents at the C1 and C3 positions.
本研究通过自动探索热解条件下β-D-吡喃木糖的势能面，揭示了一种通过同步双质子转移生成无环产物的新过渡态（TS）。采用多路径正则变分过渡态理论的量子化学方法表明，新过渡态的标准活化焓（44.9千卡/摩尔）比已确立的通道低1.5千卡/摩尔；然而，在673.15 - 873.15 K的热解范围内，后者的速率常数（k - k0）高5 - 8倍。在320 - 400 K范围内，这个差距缩小到2倍，这表明新过渡态可能会影响该低温区域内无环产物的生成。这对于β-D-吡喃木糖三聚体尤为重要，因为内部单元在C1和C3位置带有不同的取代基。
