Indicate which reaction will occur faster. Explain your reasoning. Select the si
ID: 229526 • Letter: I
Question
Indicate which reaction will occur faster. Explain your reasoning. Select the single best answer.
Reaction of 1chloropentane with sodium iodide or sodium methanesulfonate in aqueous ethanol.
a. Sodium methanesulfonate will react faster because the intermediate is more stabilized in the solvent.
b. Sodium iodide will react faster because the intermediate is more stabilized in the solvent.
c. Sodium methanesulfonate will react faster because methanesulfonate is the better nucleophile.
d. Sodium methanesulfonate will react faster because the leaving group encounters less steric hindrance.
e. Sodium iodide will react faster because the leaving group encounters less steric hindrance.
f. Sodium iodide will react faster because iodide is the better nucleophile.
Explanation / Answer
Option f is the correct option.
Here actually Sn2 substitution occurs because the substrate is primary halide.And in presence of polar protic solvent ethanol,iodide acts as good nucleophile because it is less surrounded by ethanol because of it's large size and so acts as good nucleophile.On the other hand,methane sulphonate anion of sodium methane sulphonate is good leaving group,not a good nucleophile. Since Sn2 reaction rate depends on both substrate and nucleophile concentration,so option f is the correct option.