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Aldehydes, Ketones And Carboxylic Acids

Question
CBSEENCH12008588

Discuss the preparation of aldehydes and ketones from alkenes.

Solution

Prepartion of aldehydes:
From acyl chloride (acid chloride):
Acyl chloride is hydrogenated over catalyst, palladium on barium sulphate. This reaction is called Rosenmund reduction.
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From nitriles and esters:
Nitriles are reduced to corresponding  imine with stannous chloride in the presence of hydrochloric acid which on hydrolysis give corresponding aldehyde.
RCN space plus SnCl subscript 2 space plus HCl rightwards arrow with space space space space space on top RCH equals NH
RCH equals NH rightwards arrow with straight H subscript 3 straight O to the power of plus on top space RCHO
Prepartion of ketones:
Treatment of acyl chlorides with dialkylcadmium gives ketone.
RCOCl space plus space straight R apostrophe Cd space rightwards arrow with space space space on top space straight R subscript 2 Cd space rightwards arrow space 2 RCOR apostrophe space plus CdCl subscript 2
From benzene or substituted benzenes:
when benzene or substituted benzene is treated with acid chloride in the presece of anhydrous aluminium chloride, it afford the corresponding keton. This reaction is known as Friedel - crafts acylation reaction.
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