Schiff's reaction and Tischenko reaction

(a) Schiff's reaction: this reaction restores pink colour to Schiff's reagent (aqueous solution of p-rosaniline hydrochloride decolourised through passing sulphur dioxide).

(b) Tischenko reaction: On heating benzaldehyde along with aluminium alkoxide (ethoxide) and a little of anhydrous AlCl₃ or ZnCl₂, it goes through an intermolecular oxidation and reduction (such as aliphatic aldehydes) to make acid and alcohol respectively like and react to produce benzyl benzoate (an ester).