In nitration of benzene by mixed acid the rate of reaction will be :

Options

A. `C_6H_6 = C_6D_6 = C_6T_6`
B. `C_6H_6 gt C_6D_6 gt C_6T_6`
C. `C_6H_6 = C_6D_6 gt C_6T_6`
D. `C_6H_6 lt C_6D_6 lt C_6T_6`

Answer

A

Explanation

We are now in a position to draw possible energy profiles. Since the C-D bond is stronger than the C-H bond, the P.E. of the `C_6D_6` reactant system will be lower than that of the `C_6D_6` reactant system. This will also be the case for the corresponding product systems. Because the most important difference between the two systems is the step leading to fission of the C -H and C - D bonds, both energy profiles may be combined and only this difference is then shown. The student should carefully compare the energy profile drawn here with the one given in the Text. This again illustrates the point that energy profiles are not always what they are meant to represent.