Questions CH+CI-CIC CHCI CHCl:CHCh+CCl CH3CH3+CH2CICH2CI+… Requires heat or light for initiation. The most effective wavelength is blue, which is absorbed by chlorine gas. Lots of product formed from absorption of only one photon of light (chain reaction). ■The Mechanisms? Relative Reactivities?
Mechanism: Free-Radical Chain Reaction Initiation generates a reactive intermediate. Propagation:the intermediate reacts with a stable molecule to produce another reactive intermediate (and a product molecule). Termination:side reactions that destroy the reactive intermediate
Initiation Step A chlorine molecule splits homolytically into chlorine atoms(free radicals) Cl CI:+photon (v
Propagation Step (1)" The chlorine atom collides with a methane molecule and abstracts (removes)a H,forming another free radical and one of the products (HC). H H H一CI H
Propagation Step(2) The methyl free radical collides with another chlorine molecule,producing the other product (methyl chloride)and regenerating the chlorine radical. (a) CI·+H:CH H:CI+●CH b) ·CH3 +CI:CI →CH,C1+C1·