question_answer 4)

Arrange the following compounds in increasing order oftheir reactivity in nucleophilic addition reactions. (i) Ethanal, propanal, propanone, butanone. (ii) Benzaldehyde, p-tolualdehyde, p-nitro benzaldehyde,acetophenone. Reactivity depends on two factors: Steric effect and electronic effect. Lesser the steric hindrance, higher is the reactivity.  

Answer:

The increasing order of reactivity in nucleophilic additionreactions is: (i) Butanone  propanone  propanal  ethanal (ii) Acetophenone  ptolualdehyde  benzaldehyde  p-nitro benzaldehyde.  Because presence of electron withdrawing group makes the  bond, more reactive.