Explain how many types of organic reactlons are possible.

Explanation

Common types of organic reactions are (1) Substitution reactions (2) Addition reactions 3) Ellmination reactions (4) Rearrangement reactions.
1) Substitution (Displacement) reactions: The replacement of an atom or group from a molecule by a different atom or group is known as 'substitution reaction'.
Ex : i) `CH_(4)+Cl_(2)overset(hv)toCH_(3)Cl+HCl`
(ii) `CH_(3)OH+HBrtoCH_(3)Br+H_(2)O`
2) Addition reactions: Reactions in which atoms or groups of atoms are added to a molecule are known as addition reactions.
Ex: `underset("Ethylene")(CH_(2)=CH_(2))+H_(2)tounderset("Ethane")(CH_(3)-CH_(3))`
The multiple bond breaks and then the addition takes place.
3) Elimination reactions : The molecule loses atoms or group of atoms and a multiple bond is formed. (these are actually the reverse of addition reactions)
Ex: i) dehydration :
`underset("Ethylalcohol")(CH_(3)CH_(2)OH)overset("conc." H_(2)SO_(4))tounderset("Ethylene")(CH_(2)=CH_(2)+H_(2)O`
ii) Dehalogenation:
`underset("Ethylenebromide")(CH_(2)Br.CH_(2)Br)overset(Zn)tounderset("Ethylene")(CH_(2)=CH_(2)+ZnBr_(2))`
4) Molecular rearrangement reactions : In these reactions, an atom or a group migrates from one atom to another atom, within the same molecule.
Ex: 1) n-Butane to Isobutane:
`underset("n-butane")(CH_(3).CH_(2).CH_(2).CH_(3))underset(573K)overset(AlCl_(3)//HCl)tounderset("Isobutane")(CH_(2)-overset(CH_(3))overset(|)(CH)-CH_(3))`
ii) Bezophenone oxime to Benzanilide: