The trans–gauche isomerization reaction of model 1,2-dichloroethane in water and ethylene glycol)EG(was studied by molecular dynamics (MD) simulation. With low barrier height, the reaction in EG was slower than that in water, and their difference decreased with increasing barrier height. Compared with the time-dependent diffusion model, in water, the effective diffusion coefficient was almost independent of time, whereas it decreased with time in EG. The trends were reproduced by Langevin dynamics simulation with a time-dependent friction coefficient from MD simulation. The effective diffusion coefficient in water agreed well with the prediction of the Grote–Hynes (GH) theory, whereas for EG, the GH theory overestimated the effective diffusion coefficient. It was suggested that the coupling with the slow structural relaxation of EG slows down the dynamics far from the transition state, which may slow down the overall reaction dynamics when the activation barrier is not high.

通过分子动力学（MD）模拟研究了1,2-二氯乙烷模型在水和乙二醇中的反式-高斯异构化反应（EG），其势垒高度低，在水中的反应慢于在水中的反应。随势垒高度的增加而减小；与时间相关的扩散模型相比，在水中，有效扩散系数几乎与时间无关，而在EG中，有效扩散系数随时间而减小；通过兰维文动力学模拟，再现了随时间变化的摩擦趋势。水中的有效扩散系数与Grote–Hynes（GH）理论的预测非常吻合，而对于EG，GH理论则高估了有效扩散系数。有人认为，与缓慢的EG的结构弛豫耦合会减慢动力学，使其远离过渡态，这在激活势垒不高时会减慢整体反应动力学。