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

Options

A. `overset(Theta)CH_2 - CH =CH - CH = overset(o+)O - CH_3`
B. `CH_2 = CH_2 - overset(Theta)CH - CH = overset(o+)O - CH_3`
C. `overset(Theta)CH_2 - overset(o+)CH - CH = CH - O - CH_3`
D. `CH_2 = CH - overset(Theta)CH - overset(o+)CH - O - CH_3`

Answer

C

Explanation

The octet of all atoms are complete in structures (a) and (b). In structure (d) electron deficiency of positively charged carbon is duly compensated by lone pair electrons of adjacent oxygen atom while such neighbour group support is not available in structure (c).