Aldehydes And Ketones Test - 33

Hint: Cannizaro reaction is shown by aldehydes and ketones that don't have alpha hydrogen (hydrogen on the carbon next to the carbonyl carbon).

The compounds that don't have an α−H show Cannizzaro reaction and the compounds that have an α−H show aldol reaction.

A) In trimethyl acetaldehyde there are 3 CH_3​ group attached to the α C and no α H.So, it will give Cannizzaro reaction.

B) Acetaldehyde have 3αH present next to the C=O group so it does not give Cannizzaro reaction

C) In benzaldehyde there is a benzyl group on α C So, No α H So, it will give Cannizzaro reaction.

D) In formaldehyde there is no αC so it will show Cannizzaro reaction.

Those aldehydes or ketones which have α-hydrogen atoms undergo aldol condensation reaction.

Crotonaldehyde has the aldehydic group at the C-1 position and −C=C− at the position at C-2 with 4 carbon atoms in the parent chain, thus the name is But-2-en-1-al.

Acetone is prepared by dry distillation of calcium acetate

All these are ammonia derivatives which react both with aldehydes and ketones.

In crossed Cannizzaro reaction, formaldehyde always undergoes oxidation to form formate ion while other aldehydes undergo reduction

Aldehydes lacking hydrogen atom in the alpha position undergo Cannizzaro reaction. Thus benzaldehyde with the formula C₆​H_5​CHO undergoes Cannizzaro reaction.

In Wolff-Kishner reduction only ketone group is reduced to alkyl group whereas double bond remains intact