benzyl chloride reacts faster than 1-chlorobutane. why??

Question

When treated with sodium iodide in acetone, benzyl chloride reacts much faster than 1-chlorobutane, even though they are both primary alkyl halides. Why does this rate difference occur?? also, would an SN2 reaction occur when crotyl chloride is placed in sodium iodide in acetone. If so, would it occur at room temp. or only once heated. Would an SN2 reaction occur if it was in silver nitrate in ethanol???-and if so, at room temp. or when heated? Thanks for any help!

Answer 1

Benzyl chloride reacts faster because it has an aromatic system which make the benzylic carbon prone to nucleophilic attact especially with the more electronegative iodide ion. 1-chlorobutane, on the other hand, doesn't have this system, and chloride ion is weaker leaving group than the iodide ion.