The hydrolysis of tert-butyl chloride proceeds more rapidly in a solvent mixture which is 70% water/30% acetone than in one which is 30% water/70% acetone.Why? A)The transition state in the carbocation formation step is better stabilized in the more polar solvent mixture. B)The reaction proceeds by an S_N2 mechanism wherein the rate is increased by increasing the concentration of the nucleophile water. C)The reaction proceeds by an S_N1 mechanism wherein the rate is increased by increasing the concentration of the nucleophile water. D)The solvent which contains a greater percentage of water is less polar,and this destabilizes the tert-butyl chloride. E)none of the above

Question

Quizplus · Accepted Answer

The transition state in the formation of carbocation (which is the rate-determining step of the reaction) is better stabilized in the more polar solvent mixture. This is because the polar solvent mixture provides a better solvation environment for the carbocation intermediate, which stabilizes the positive charge on the carbon atom. The increased stabilization lowers the activation energy required for the reaction to occur, thereby increasing the rate of the reaction. The concentration of the nucleophile (water) is not the main factor affecting the rate of the reaction. Therefore, options B and C are incorrect. The solvent which contains a greater percentage of water is more polar (not less polar as described in option D), but the question stem correctly states that the reaction proceeds more rapidly in the 70% water/30% acetone solvent mixture. Thus, option D is also incorrect.

The Hydrolysis of Tert-Butyl Chloride Proceeds More Rapidly in a Solvent