Question

How can I illustrate antimarkovnikov's rule by the addition of hydrogen bromide to propene in the presence of benzoyl peroxide?

Answer 1

You write the mechanism for the reaction.

Explanation:

This is a free radical reaction, so it has initiation, propagation, and termination steps.

Initiation

The chain is initiated by free radicals produced by cleavage of an `"O-O"` bond in the benzoyl peroxide.

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The benzoyl radicals extract a hydrogen atom from an `"HBr"` molecule to produce bromine radicals.

`"PhCOO·" + "H-Br" →"PhCOOH" + "·Br"`

Propagation

The bromine radical adds to the propene to form the more stable 2° radical.

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The 2° radical reacts with another HBr molecule to produce 1-bromopropane and a bromine radical to continue the process.

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Termination

Eventually two free radicals hit each other and produce a molecule of some sort.

`"Br·" + "·Br" → "Br"_2`

`"CH"_3"-" stackrel(·)("C")"H-CH"_2 "-Br" + "·Br" → "CH"_3"-CHBr-CH"_2"-Br"`

`"2CH"_3"-" stackrel(·)("C")"H-CH"_2 "-Br" → "Br-CH"_2"-CH(CH"_3")-CH(CH"_3")-CH"_2"-Br"`

The process stops here because no new free radicals are formed.