Preparation of Aldehyde: Rosen-mund and Stephan Reaction

 

1. From Acyl Chloride (Rosen-mund Reaction)

When acyl chloride is hydrogenated with palladium barium sulfate, benzaldehyde is produced as a product.

2. Form Nitriles 

i) Stephan Reaction

When nitrile are react with stannous chloride and HCL it give imine which on further hydrolysis gives Aldehyde.

ii) When Nitriles are react with di-iso butyl  aluminium hydride to produce imine which on hydrolysis yield aldehyde as a product.  

3. From Ester

Easter on reaction with DIBAL-H (Di-iso butyl aluminium hydride) produce aldehyde and alcohol.

4. Form Hydrocarbons 

i) By Oxidation of Toluene

When Chromyl-chloride oxidise the methyl group of toluene, a chromium complex is obtained which on further hydrolysis yield benzaldehyde.

ii) By Photochlorination 

When methyl-benzene is photochlorinated gives benzal chloride a which on further hydrolysis yield benzaldehyde. 

5. Gatter-man Koch Reaction

When toluene is react with carbon monoxide and HCL in presence of anhydrous AlCl3. Benzaldehyde is produced as a product.