Question

Resonance structures of propenal are given below. Which of these resonating structures is more stable ? Give reason for your answer.
`CH_(2)=underset("I")(CH-CH)=O harr underset("II")(overset(o+)(CH)_(2)-CH=CH-overset(Theta)(O))`

Answer 1

Structure (I) is more stable. Since there is no charge separation and the two double bonds are in conjugated positions. Moreover all the atoms (C and O) have complete octel.