Question

Which of the following resonating structures of $1$-methoxy $1,3$ -butadiene is least stable?

• A. $\overline{ C}H _{2}- CH = CH - CH = \overset{+}O - CH _{3}$
• B. $CH _{2}= CH -\overline{ C}H - CH = \overset{+}{O } - CH _{3}$
• C. $\overline{ C}H _{2}- \overset{+}CH - CH = CH - O - CH _{3}$
• D. $CH _{2}= CH - \overline{C}H - \overset{+}{C}H - O - CH _{3}$

Answer 1

Answer: (C)

The molecule in which all the atoms have complete octet is more stable. Also, more the number of resonating structures, more will be the stability.

(a) and (b) have complete octet but in (c) and (d) all atoms do not have complete octet. Hence (c) and (d) are unstable.