(i) Cannizzaro reaction: Aldehydes which do not have an a-hydrogen, undergo self oxidation and reduction (disproportionation) reaction on treatment with concentrated alkali. In this reaction one molecule of the aldehyde is reduced to alcohol while another is oxidised to carboxylic acid salt.
(ii) Cross aldol condensation: When aldol condensation is carried out between two different aldehydes and/or ketones, it is called cross aldol condensation.
If both of them contain α -hydrogen atoms. It gives a mixture of four products
