A reaction is either concerted, or stepwise, depending on whether an intermediate has a significant lifetime at that temperature. ... Concertedness of reaction and lifetimes of intermediates will also be significantly affected by quantum effects such as tunnelling and zero-point energy for proton and hydride transfers, as found by previous simulations. Quantum effects are not included in the current work, which applies only classical dynamics simulations (with a QM/MM potential). In this case, so-called intermediates 1 and 2 are predicted to have negligible lifetime even without zero-point and tunnelling corrections. Therefore these are not actually intermediates and the conclusions are incorrect. The results indicate that the reaction is concerted.