HALOGENATION OF PROPANONE

Review

Overall Reaction	Pk + I2 → PI + H+ + I-
Proposed Mechanism
Overall Rate of Consumption of Iodine	-d[I2]/dt = + k2[Pe][I2]
Steady State Approximation	d[Pe]/dt = 0
Overall Rate of Production of Pe	d[Pe]/dt = + k1[H+][Pk] - k-1[Pe][H+] - k2[Pe][I2]
From Applying the Steady State Approximation	[Pe]ss = + k1[H+][Pk] / (k-1[H+] + k2[I2])

Eliminating the Steady State Species from the Expression for the Overall Rate of Consumption of Iodine

The derived equation for the steady state concentration of the enol form of propanone

[P_e]_ss = + k₁[H⁺][P_k] / (k_-1[H⁺] + k₂[I₂])

-d[I₂]/dt = + k₂[P_e][I₂]

This results in

-d[I₂]/dt = + k₁[H⁺][P_k] / (k_-1[H⁺] + k₂[I₂])

-d[I₂]/dt = + k₁k₂[H⁺][I₂][P_e][P_k] / ( k_-1[H⁺] + k₂[I₂])

-d[I₂]/dt = + k₁k₂[H⁺][I₂][P_k] / ( k_-1[H⁺] + k₂[I₂])