Generally, non-polar solvents promote the S N 2 mechanism, whereas polar solvents favour an S N 1 mechanism by solvating the ions to form solvent-separated ion pairs. In DCM (dielectric constant, ε, of 8.93) at 223 K, the β-glycoside product is favoured, suggesting an S N 2-like mechanism. However, this preference diminishes at 303 K, indicating a change to S N 1-like mechanism. This behaviour further illustrates the complexity of the competition between the reaction mechanisms and the importance of an accurate description of the subtle interactions with the solvent.