Question

The decreaing order of the rate of niration of the following compounds is
I. Benzene, II. `C_(6)D_(6)`
III. Nitrobenzene, IV Chlorobenzene
A. `(I) gt (II) gt (III) gt (IV)`
B. `(I) gt (II) gt (IV) gt (III)`
C. `(I) = (II) gt (IV) gt (III)`
D.

Answer 1

Correct Answer - `c`
Rate is faster when the substiuent activates the ring (`+I` or/and `+R, o//p`) and the rate is slower when the substituent deactivates the ring `(-1, -R,m)`. Halogen deactivates the ring `(-I, +R, -I gt +R)` b ut the orientation is `o//p`.
Rate of `C_(6)H_(6) = C_(6) D_(6)`, since no kinetic isotope effect is observed when `H` is reaplaced by `D` .
Hence, the same is as given in `(c).(I) = (II) gt (IV) gt (III)`.