Predict the order of reactivity of the following compounds in `S_(N)1` reactions :

Explanation

(i) is secondary halide and other three are tertiary halides. Therefore, (i) will be least reactive. Comparing (ii), (iii) and (iv), we know that reactivity increases as `"chloride" lt "bromide" lt "iodide"`. Thus, the compounds can be arranged in increasing order of reactivity as : `(i) lt (ii) lt (iii) lt (iv)`.