Question

The solvent in which the hydrolysis of t-butyl took place was approximately 75% water and 25% acetone by volume.

A) What effect would increasing the % of acetone have on the rate of hydrolysis?

B) What effect upon the rate of hydrolysis could be expected had you used isopropyl alcohol, instead of acetone?

Answer 1

A) hydrolysis of t-butyl follows SN1 mechanism that means in first step (rate determining step) t-butyl cation is formed and then hydrolysis takes place to produce t-butyl alcohol. If the acetone percentage increases then polarity of solvent decreases. If polarity of solvent decreases then rate of SN1 reaction also decreases.

Hence increasing the % of acetone will decrease the rate of hydrolysis.

B) Isopropyl alcohol is more polar than acetone so rate of hydrolysis increases if you use isopropyl alcohol instead of acetone.