Addition Reactions


In this type of reaction, atoms are ADDED to an UNSATURATED organic molecule (alkene or alkyne). The total number of atoms in the original molecule will increase.
The are essentially 4 types of addition reactions : Functional groups completely change.

HYDROGENATION

Hydrogen H2 is added to an alkene.
Reaction condition: catalyst Pt / Ni / Pd


Diagram 1

HYDROHALOGENATION

A hydrohalogen (such as HCl) is added to an alkene.
Reaction condition: No water present.


Diagram 2

Another example of HYDROHALOGENATION
This example shows what happens if the alkene is much longer.


Diagram 3
This is called Markovnikov's Rule.
When a compound HX reacts with a alkene, the hydrogen atom H from HX will attach itself to the C that has the greater number of hydrogen atoms, and the X will attach itself to the carbon with the fewer number of hydrogen atoms.

HALOGENATION

A halogen such as Br2 reacts with an alkene.
Reaction condition: Room temperature.


Diagram 4

HYDRATION

This is a reaction with water and an alkene.
Reaction condition: reaction must take place in a dilute, strong acid which must act as a catalyst. Example sulphuric acid H2SO4 or phosphoric acid H3PO4


Diagram 5
Another example of HYDRATION
This example shows what happens if the alkene is much longer.


Diagram 6
This is another example of Markovnikov's Rule.




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