Question

What solvent would be best to carry out the substitution of the benzyl iodide shown below and why? H2N solvent at 70 °C 1.0 equivalents Methanol, because this reaction performs best with a polar protic solvent to solvate charged intermediates. DMSO, because this reaction performs best with a polar aprotic solvent which will dissolve the nucleophile without hydrogen bonding. O Hexanes, because this reaction performs best with a nonpolar solvent to reduce the energy of the transition state. This reaction performs best without solvent.

Hi, could you please give an explanation to? thanks!

Answer 1

The best option for the above question is the option 2 (DMSO), Here the reaction undergoes by the SN2 mechanism,

1. For the SN2 mechanism the nucleophile must be have highest nucleophilicity, this acn be attributed only the solvent is dissolved in the Polar aprotic solvent. (So that no hydrogen bonding is formed),
2. If we use the polar protic solvent hten the nucleophile will form the hydrogen bonding, then leads to the poorer nucleophile,
3. If we use the Hexane, amine will not dissolve in much extent.

Thankyou,