The determination of the residence time distribution (RTD) and the Bodenstein numbers under reactive synthesis conditions provides a more accurate representation of the hydrodynamic situation in a reactor with a permanently changing magnesium bed. Mean Bo under reactive conditions were found to be lower than under non-reactive, but standard deviations remain higher for fine magnesium turnings than for coarse turnings (table 3 and figure , for details of the non-reactive experiments see part 1, exemplary distribution functions within ESI). On average, the Bodenstein numbers decreased by about 66 % and 74 % for the coarse and fine magnesium turnings, respectively (mean number of RTD measurements: 3.8 for coarse turnings, 5.8 for fine turnings). The mean Bo for the use of pump D with fine magnesium turnings and a displacement of the tracer toluene by pure THF even decreased by 90 %. The decrease in Bodenstein numbers occurs regardless of the fact that portions of the magnesium turnings are replenished during synthesis. The influence of the decreasing magnesium mass should be limited to the period of a single measurement run. This assumption does not consider that the composition of the magnesium bed changes during a synthesis. The particle size distribution becomes broader since magnesium turnings react and their size decreases. Voids may form within the magnesium packing that may lead to preferential short-circuit flow paths. Since magnesium turnings are repeatedly replenished during synthesis, the reactor was operated until steady-state and complete conversion of the halide reactant 1 was achieved before the first residence time experiment was started. Thus, a constant particle size distribution was assumed for every measurement run. Even though these particle size distributions do not exactly match the particle size distribution of the mixed turnings in part 1, the impact of the particle size distribution on the residence time distribution is also evident for the reactive case in figure . A broad particle size distribution (coarse Mg turnings) results in higher Bo when the tracer toluene is displaced from the reactor system. For non-reactive measurements a significant influence of the jogging motor on the axial dispersion was observed. This effect was also noticeable under reactive conditions. When coarse magnesium turnings were used and the jogging motor was omitted, a maximum Bodenstein number of 10 was measured, regardless of the used pump (see ESI). This value is smaller than the Bodenstein numbers in table 3 and figure and illustrates the positive effect of the jogging motor on flow behaviour as already mentioned in part 1 for the non-reactive case. For most cases, mean residence times under reactive conditions are higher than the calculated hydrodynamic residence time. For the coarse magnesium turnings, on average, the mean residence time increases by 11 % compared to the unreactive case and by 4 % compared to the hydrodynamic residence time. For the fine magnesium turnings, on average, the mean residence time increases by 26 % compared to the unreactive case and by 13 % compared to the hydrodynamic residence time. Assuming that the reaction does not influence the RTD experiments except for the changes within the magnesium bed, the magnesium bed and its impact on the flow behaviour is responsible for the increase in 𝑡̅ .