Question

(i) Write resonance structures of CH₂ = CH-CHO. Indicate relative stability of the contributing structures.

(ii) In which C-C bond of CH₃CH₂CH₂Br, the inductive effect is expected to be the least?

Answer 1

(i) Structure I Most stable, more number of covalent bonds, each carbon and oxygen atom has an octet and no separation of opposite charge. In structure II, negative charge on more electronegative atom and positive charge on more electropositive atom Structure III does not contribute as oxygen has positive charge and carbon has negative charge, hence least stable.

Stability: I > II > III

(ii) Magnitude of inductive effect diminishes as the number of intervening bonds increases. Hence, the effect is least in the bond between carbon-3 and hydrogen.