The alternative, second model (model 2) is also based on the assumption that ethyl chloride is produced from ethanol and diethyl ether, but via intermediate states. This approach of ethyl chloride formation via various parallel reactions was proposed in our previous work (Bukhanko et al., 2013). Thus, according to the following reaction scheme, 3 main reactions can be listed as RDS for ethyl chloride formation. The initial step, the ethoxy formation from ethanol is very fast and the concentration of H species, formed at this step, is negligible low and has no effect on further steps. In the calculations the concentration of the ethoxy species was taken as equal to the ethanol concentration. The reaction I in this model can be considered as not RDS step and the equilibrium constant for this step was not calculated. The last step V was not considered as RDS. The derivation of this model is presented in the Electronic Supplementary Content 1.