Consider the cation $C X_{6} H X_{5} - CH = CH - CH X_{2} X^{+}$ (a phenyl group attached to an allyl cation). Count each resonance structure in which the positive charge sits on a different carbon atom as a separate structure, counting only one Kekule drawing for each location of the charge (side chain carbons or ring carbons). How many resonance structures does this cation have?

Numerical answer type, tolerance 0.5.

Answer: 5

Mark alternate atoms starting from the terminal

CH X_{2}

. The atoms that can bear the positive charge are the terminal

CH X_{2}

, the chain carbon next to the ring, the two ortho carbons and the para carbon. That makes 1 + 1 + 2 + 1 = 5 structures, confirmed by a Python count. The answer is 5.

Practice General Organic Chemistry I: Electronic Effects More on Stability of resonating structures and conjugated species

Previous questionNext question

Answer: 5

More questions on Stability of resonating structures and conjugated species