Benzaldehyde is the simplest aromatic aldehyde. It occurs in bitter almonds in the form of its glucoside,amygdalin ( C20H27O11N) . When amygdalin is boiled with dilute acids, it hydrolyses into benzaldehyde, glucose and HCN
Benzaldehyde is also known as oil of bitter almonds.
Laboratory Method of preparation of Benzaldehyde
It is conveniently prepared by boiling benzyl chloride with copper nitrate or lead nitrate solution in a current of carbon dioxide.
[ 2HNO2 ———→ NO + NO2 + H2O ]
Preparation of benzaldehyde from toluene
Benzaldehyde is prepared by side chain chlorination of toluene to benzylidene chloride followed by hydrolysis.
Benzaldehyde is a colorless liquid (boiling point 452 K) with the smell of bitter almonds. It is used in perfurmery and dye industry for making dyes like malchite green.