1.

Arrange the following compounds in increasing order of their reactivity in nucleophilic addition reactions. Benzaldehyde , p-Toualdehyde, p-Nitrobenzaldehyde , Acetophenone.

Answer»

Solution :Order of reactivity: acetophenone `lt` p-tolualdehyde `lt` benzaldehyde `lt` p-nitrobenzaldehyde. Due to hyperconjugation, methyl GROUP in p-tolualdehyde is ELECTRON releasing because of which the positive charge on carbonyl carbon decreases. Due to resonance effect (electron withdrawing effect of nitro group) in p-nitrobenzaldehyde, the positive charge on carbonyl carbon increases. GREATER the positive charge on carbonyl carbon, more is the reactivity.Further, it may be noted that ketones are less reactive than ALDEHYDES.


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