The influence of temperature was then examined with 1 M solutions in acetonitrile with a 150 µm thick membrane. Without surprise, the rate of diffusion of epoxide 1a increases with the temperature between 0 °C and 60 °C leading, after 24 h, to a loss of its enantiopurity of 30% and of 85% respectively. Enantiopure diol 2a poorly diffuses under these conditions with a slight decrease in the enantiomeric excess. After 24 h at 60 °C, a loss of 10% ee was observed. These experiments demonstrated that a large range of temperature can be used in such processes keeping a high selectivity of diffusion between epoxide 1a and diol 2a. Four different thicknesses of the PDMS membrane (100, 150, 200 and 250 µm) were then examined with 1 M solutions in acetonitrile at room temperature. 100 µm thick membrane exhibits an improved diffusion concerning the epoxide 1a but between 150 µm and 250 µm the membranes show the same diffusion profile. Concerning the transfer of diol 2a, no difference was observed with the four thicknesses tested. For a balance between mechanical properties and diffusion behaviors, 150 µm thick membranes were used in the following experiments.