The difference of these two reactions

[Questionasker]

Hi there

im really struggling to get my head around the difference between electrophilic addiction and free radical addition. I know the steps on these two different reactions but I just don’t get how they can differ from each other. One of the reactants, for an electrophilic addition can be simple like hydrogen bromide, the bond breaks from the double,triple bond acting as a Bronsted lowery base and the bromide is left with an unpaired electron, which I believe should be known as a free radical, so then it will form a bond with one of the carbocations and produce a halogenoalkane, for example.
 

I really just can’t distinguish the  the two of them and I’d really love some help. 
 

 

thank you

[chenbeier]

No, in case of the HBr  you get H+ and Br-. These are ions and no radicals . Radicals  habe online one unpaired  electron.           Like Cl2 => 2Cl*

In Br- the electron is paired with the one of bromine.  8 electrons in outer  shell.

Edited December 30, 2020 by chenbeier

[Questionasker]

I don’t get how Br- can’t be a radical since I believe the hydrogen bromide undergoes homolytic fission, like Halogen molecules in free radical addition. To me they both seem the same but with slightly different steps.

[chenbeier]

No it doesnt go homolytic reaction. Electrophil means some attraction to electron rich area. This means electrophil are positive like NO2+, Br+,H+,etc.

[studiot]

1 hour ago, Questionasker said:

I don’t get how Br- can’t be a radical

This might help

 

Quote

Carnduff

Atoms or groups of atoms with an odd number of valency electrons are called radicals.

How many valency electrons did chenbeier say Br^-  has ?