Anti-Markovnikov addition of HBr (peroxide effect, Kharasch) (HBr + alkene + peroxide (ROOR) → radical chain; Br adds to less substituted C.)

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HBr + alkene + peroxide (ROOR) → radical chain; Br adds to less substituted C.

What each symbol means

SymbolWhat it stands for
Br·Adds to less hindered alkene carbon; H· completes chain
ROORDialkyl peroxide initiator (generates RO· which abstracts H from HBr)

When to use this

Peroxides / radical initiators; does NOT apply to HCl or HI the same way in standard JEE framing (H–Cl bond too strong for propagation).