General formula for alkane is CnH2n+2
Examples
Alkanes undergo free radical substitution reactions.
Homolytic fission :
During homolytic fission, bond pair electrons are equally distributed between two bonded atoms.
This reaction forms free radicals.
Free radicals have unpaired electrons.
Free radicals are highly reactive.
The dot beside Cl represents an
unpaired electron and Cl is a free radical.
Heterolytic fission
During heterolytic fission, bond pair electrons are equally distributed between two bonded atoms
Due to heterolytic fission, electrophile and nucleophile are formed.
Homolytic fission produces free radicals
Heterolytic fission produces nucleophiles and electrophiles.
Free radical substitution
It has three steps
1. Initiation
During this stage, free radicals are formed by hemolytic fission in the presence of sunlight.
The process is always endothermic.
2. Propagation
More free radicals are formed
It has steps that are both endothermic and exothermic.
3. Termination
All the free radicals formed react to make product.
Always an exothermic process.
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