APPARATUS REQUIRED:
1)conical flask
2) KMno4
3) Anhydrous Na2Co3
4) Bone charcoal etc.
5) Conc.H2So4
THEORY
Benzoic acid is prepared by the oxidation of benzaldehyde with the help of KMnO4 in presence of alkali.
Benzoic acid is a compound with the chemical formula C7H6O2, commonly found in nature and used in various industrial applications.
PROCEDURE
5ml benzaldehyde, 3g Na₂Co3, 4g KMnO4 & 100 ml distilled water was mixed in a 250ml conical flask fitted with an air condenser. The mixture was heated gently for half an hour until all oily drops of benzaldehyde disappeared & MnO₂ was precipitated. The solution was Cooled, The filtrate with conc. H2So4 when white ppt of benzoic acid was obtained & washed with cold water. Purification was done as below recrystallized the benzoic acid from minimum quantity of boiling water using a little bone charcoal, it necessary collected the pure crystals by suction filtration, washed with a little cold water & dried it between the folds of a filter paper by pressing.
RESULT
Hence, the preparation of benzoic acid by the oxidation of benzaldehyde is done.
Appearance:White Shining crystals.
yield: 5gm
Melting point: 121°C
PRECAUTION:
1) All apparatus should be cleaned & dried before experiment.
2) Boil the solution until the oily drop benzaldehyde disappears.
3) Collect the crystal gently & carefully.