In the presence of organic peroxides, addition of HBr to propene gives predominantly:
A1-bromopropane (anti-Markovnikov)
Bpropan-1-ol
C2-bromopropane (Markovnikov)
Dpropane
Answer & Solution
Correct answer: A. 1-bromopropane (anti-Markovnikov)
Kharasch peroxide effect: HBr in the presence of organic peroxides (e.g. benzoyl peroxide) adds **anti-Markovnikov** via a free-radical mechanism. Br ends up on the **less** substituted carbon. Product: 1-bromopropane.
Why: the radical chain involves a Br• radical adding to the alkene first. Br• prefers the less-substituted carbon, forming the more stable carbon radical. Then HBr donates H• to complete the addition.
Notably, the peroxide effect is **specific to HBr**. HCl and HI don't show it.
Related questions
Nitration of toluene (methylbenzene) on the lab gives products mostly at:Benzene satisfies Hückel's rule with $4n + 2$ pi electrons for $n =$:Adding HBr to propene CH$_3$-CH=CH$_2$ in absence of peroxide gives mainly:The general formula for alkanes is:
Benzene is best described by:According to Hückel's rule, a planar cyclic compound is aromatic if it has:Wurtz reaction is used to prepare:
When propene reacts with HBr,