Describe the general method of meditation of aromatic ketones and their general properties
Answers
Answer:
Toluene (methylbenzene) is oxidised to chromium complex with a solution of chromyl chloride (CrO2Cl2) in CCl4 or CS2, which on hydrolysis gives aldehyde. Preparation of aldehydes by this method is known as Etard process.
Benzaldehyde is prepared by etard process
Alternatively, toluene can be oxidised to aldehyde with chromium trioxide in acetic anhydride.
preparation of benzaldehyde from toluene
Side chain halogenation of toluene followed by hydrolysis yields aldehydes.
Preparation of aromatic aldehydes by halogenation
Benzene is treated with CO and HCl in the presence of lewis acid like anhydrous AlCl3 to give benzaldehyde. Preparation of aldehydes by this method is known as Gatterman-Koch reaction.
Preparation of benzaldehyde by gatterman-Koch reaction
Preparation of Aromatic Ketones
Friedal-Crafts acylation is one of the most convenient methods for the preparation of aromatic ketones. Friedal-Crafts acylation reaction involves the treatment of benzene or substituted benzene with acid chloride or acid anhydride in the presence of a lewis acid such as anhydrous AlCl3 to form corresponding ketones.
Preparation of aromatic ketones by friedel-Crafts acylation
Acid anhydride is used in the following example :
preparation of ketones by friedel Crafts reaction