Question

Which of the aldehyde is most reactive?

• A. $\mathrm{C}{}_6\mathrm{H}{}_5\mathrm{CHO}$
• B. $\mathrm{CH}{}_3\mathrm{CHO}$
• C. $\mathrm{HCHO}$
• D. All the equally reactive

Answer 1

Answer: (C)

Among carbonyl compounds, reactivity decrease with increase in alkyl groups as alkyl groups (+ I effect) decrease positive character on C-atom. Thus, the correct order of reactivity is-
$\mathrm{HCHO}>\mathrm{CH}{}_3\mathrm{CHO}>\mathrm{C}{}_6\mathrm{H}{}_5\mathrm{CHO}$