Question

What is the peroxide effect? Explain giving one example.

Answer 1

Hint: Peroxide effect is used in case of alkenes and is also known by the name of the Anti Markovnikov's rule according to which the negative part of the chemical reagent to added to that carbon of the double bond which has the higher number of the hydrogen atoms. Now with the help of this, you can easily answer the given statement accordingly.

Complete step by step answer:
First of all, let’s discuss the peroxide effect. By the term peroxide effect, we simply mean the addition of the hydrogen bromide i.e.HBr to the unsymmetrical alkenes against the Markownikoff’s rule.
In Markownikoff’s rule, the negative part of the chemical reagent HBr i.e. bromide ion is attached to that carbon atom of the double bond which consists of the lesser number of the hydrogen atoms.
But in case of the peroxide effect, the negative part of the chemical reagent HBr i.e. bromide ion is attached to that carbon atom of the double bond which consists of the greater number of the hydrogen atoms. Since, this reaction takes place only in the presence of the peroxide, this reaction is known as the peroxide effect.
Peroxide effect is also known by the name of the Anti Markovnikov's rule.
Example: When propene is made to react with the HBr in the presence of peroxide, then the negative part of the reagent i.e. the bromide ion is attached to the $C{{H}_{2}}$ group of the double bond which consists of the higher number of hydrogen atoms and thus, results in the formation of the n-propyl bromide.
The chemical reaction is supposed to occur as;
$C{{H}_{3}}-CH=C{{H}_{2}}+HBr\xrightarrow{peroxide}C{{H}_{3}}-C{{H}_{2}}-C{{H}_{2}}-Br$

Note:
Unsymmetrical alkenes are those alkenes in which the number of atoms attached on both sides of the double bond is not same like in propene, but-1-ene etc. whereas on the other hand, the alkenes which consists of the same number of the atoms on both sides of the double bond are called as the symmetrical alkenes like ethene, but-2-ene etc.