Ph-CH=CH2+BrCCl3 peroxide ⟶ Product is

Name: Problem 72, Chapter 3: Advanced Problems in Organic Chemistry for Competitive Examinations
Uploaded: 2021-09-07T05:39:00-08:00
Duration: 1 min 33 s
Channel: Alkendra Singh
Description: Ph-CH=CH2+BrCCl3 peroxide ⟶ Product is

Key Concepts

Radical Initiation

This concept involves the generation of radical species, typically by the decomposition of a peroxide under heat or light. In radical reactions, the initial step is the homolytic cleavage of a bond to form radicals, which then propagate the chain mechanism by reacting with other molecules.

Radical Addition Mechanism

In a radical addition, a radical species adds to a double bond to form a new radical intermediate. This intermediate then reacts with another molecule (often a halogenated compound) to terminate the radical, leading to a product where substituents have been added across the double bond. The reaction proceeds via a chain mechanism involving initiation, propagation, and termination steps.

Regiochemistry in Radical Reactions

Radical intermediates often display selectivity based on the stability of the resulting radical. In alkenes, the addition of a radical will preferentially occur in a manner that yields the more stabilized radical intermediate (e.g., a benzylic radical), which then leads to regioselective product formation during subsequent steps.

Peroxide Effect

The peroxide effect, also known as the Kharasch effect, refers to the phenomenon where the presence of peroxides favors a radical mechanism over a polar mechanism. Peroxides decompose to generate radicals, which can override the usual ionic reaction pathways and lead to different regio- or stereochemical outcomes in addition reactions.

Stabilization of Benzylic Radicals

Benzylic radicals benefit from resonance stabilization provided by an adjacent aromatic ring. This stabilization makes the formation of benzylic radicals more favorable, thereby influencing the regioselectivity of radical additions to alkenes such as styrene.

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