Aldol condensation easy mechanism

Aldol Condensation 

(Ald +ol) = aldehyde + alcohol 

Aldehydes or Ketones  having at least one alpha H atom, undergo condensation reaction in presence of dilute alkali to give beta hydroxy aldehyde or beta hydroxy ketone which are called as Aldol.

*beta hydroxy ketone is also called as Aldol instead of ketol because reaction involves the same mechanism path.

Mechanism 

Aldol condensation is  a nucleophilic addition reaction. 

It involves three steps 

1. Formation of  a Carbanion (nucleophile) 

    * Alpha H atoms are acidic in nature and easily       replaceable as a proton .

2. Nucleophilic attack on carbonyl carbon atom 

    * Due to the difference in electronegativity of oxygen and carbon atom, carbonyl group is polar in nature.  Electrons are shifted towards more electronegative oxygen atom as a result carbon acquires positive and oxygen attains a negative charge.

Now electron rich Carbanion attacks on electron deficient carbon of  carbonyl group to form the addition compound. 

3. Proton transfer

 Negatively charged oxygen accepts proton from water to give Aldol.