Please give the mechanism of Canizzaro Reaction.

Cannizzaro reaction: The disproportionation reaction of aldehydes without α-hydrogens in presence of a strong base to furnish an alcohol and a carboxylic acid is called Cannizzaro reaction. One molecule of aldehyde is reduced to the corresponding alcohol, while a second one is oxidized to the carboxylic acid.

2 RCOH RCOOH + ROH

Mechanism of Cannizzaro reaction: 

The reaction begins with nucleophilic attack of hydroxide on the carbonyl centre. The resulting anion attacks another molecule of aldehyde, transferring hydride.

In the final step of the reaction, the acid and alkoxide ions formed exchange a proton. In the presence of a very high concentration of base, the aldehyde first forms a doubly charged anion from which a hydride ion is transferred to the second molecule of aldehyde to form carboxylate and alkoxide ions. Subsequently, the alkoxide ion acquires a proton from the solvent.